sustainability

Article Sustainable Urban Regeneration for Shrinking : A Case from Japan

Yupeng Wang 1,* and Hiroatsu Fukuda 2,3,*

1 School of Human Settlement and Civil Engineering, Xi’an Jiaotong University, Xi’an 710049, 2 School of Architecture and Civil Engineering, Chengdu University, Chengdu 610106, China 3 Department of Architecture, The University of Kitakyushu, Kitakyushu 808-0135, Japan * Correspondence: [email protected] (Y.W.); [email protected] (H.F.); Tel.: +81-093-695-3242 (H.F.)  Received: 13 December 2018; Accepted: 8 March 2019; Published: 12 March 2019 

Abstract: is leading to a shrinking size in industrialized countries. In some developing countries, because majority of the population is concentrated in big cities, the population in undeveloped cities has begun to decline. Japan experienced rapid urban expansion surrounding industrial districts, including steeply sloped areas, between the 1950s and 1970s. In the past forty years, Japan’s population has decreased, and the average age of the population is increasing. The reduction in the size of cities, following population decreases is becoming an important issue, and the study of sustainable, concentrated to cope with shrinking city size is, therefore, necessary. We have conducted a case study using Yahatahigashi-ku to determine its redevelopment potential, based on a combination of urban geographic data. This paper (1) presents a typical case study using Geographic Information System (GIS) data to evaluate an aging and shrinking society; (2) explores the GIS design approaches configured for an aging society; and (3) evaluates the optimization of environmental performance for an urban regeneration plan. The primary factors related to this case study included, a declining population, mixed urban , and the placement of public facilities. We developed a method involving the slope degree to evaluate land-use to model the importance of informational evaluation in the urban planning process. This method could contribute to the urban regeneration for an aging society and could also be applied to other aging and shrinking cities, in mountainous regions.

Keywords: shrinking cities; geographic information; slope degree; aging society; urban regeneration; shadow restriction; compact city

1. Introduction Aging populations and shrinking cities are increasing internationally, in locations such as the , Germany, and Japan [1,2]. In Japan, the aging population and shrinking cities have led to serious problems, which includes declines in community vitality in most of Japan’s secondary cities. As these population changes are expected to continue, sustainable urban design and renovation are becoming increasingly important [3]. Comprehensive information evaluation and analysis is essential for the urban redevelopment process, particularly, given Japan’s population status and geographic characteristics.

1.1. Aging Cities The global share of people, aged 60 years of age or over, increased from 9.2% in 1990 to 11.7% in 2013, and is expected to continue increasing to reach 21.1%, by 2050 [4]. Currently, approximately two-thirds of the world’s older population is living in developing countries, and by 2050, nearly 80%

Sustainability 2019, 11, 1505; doi:10.3390/su11051505 www.mdpi.com/journal/sustainability Sustainability 2019, 11, 1505 2 of 14 of the older population will be living in developing countries [4]. Facing the problem of aging cities is, therefore, a global concern, and the World Health Organization published a guide to engage cities in becoming more age-friendly to better tap into the potential that the older population can provide [5], which represents a significant effort to adjust the focus of urban planning, to this aging situation. An aging society is defined as that in which the percentage of the population over 65 years of age, is higher than 25%. A percentage higher than 50% produces a limitative colony, which is a social community that is difficult to maintain. In Japan, the average life span is 83.7 years, which is the longest in the world [6], so the problem of an aging population is more serious than that faced by most other countries. In 2010, 23.0% of the total Japanese population was aged 60 years or older, and this age group is predicted to reach 39.9%, by 2060 [7], which makes the aging of the population a matter of urgent interest in Japan.

1.2. Shrinking Cities Around the World The shrinking of cities, as a result of declining urban population has attracted increasing attention within the global scientific community [8]. A shrinking city is defined as an that has experienced demographic decline, economic downturn, and geographic contraction [9]. The technological revolution created a new global economic pattern [10,11], which has led to the outflow of capital and human power [12]. Urban decline during the processes of is more remarkable in cities supported by a single industry [13]. Decreasing birth rates and population size have further accelerated the reduction in the use of urban public facilities in Japan. New housing and community services could promote a greater life quality, and the concentration of urban facilities could increase the urban efficiency. In Japanese cities, the ideal , along bus lines, is 40 inhabitants per ha, and 50 inhabitants per ha, along metro lines [14]. Population density appears to have a strong relationship with the quantity of commercial facilities, within a walkable distance [15]. Density values should, therefore, be considered in the process of urban redevelopment, to achieve efficient organization of public transportation and commercial operations. Shrinking cities must be radically redesigned to be both better and smaller [16]. The prevalence of shrinking cities in Japan has recently become a serious issue, particularly as the population growth rate has decreased since 2015 [17]. Shrinking cities have also been observed in other industrial countries, such as the United States, the United Kingdom, and Germany. As of 2016, the estimated population of , Michigan, was just over 0.677 million, which represents a steep decline from a peak of more than 1.8 million in the 1950s. According to current estimates, Detroit’s population will continue to fall to just 0.61 million people, by 2030. The population of Liverpool, England, and , Germany, reached historic peaks in the 1930s, with populations between 0.7 and 0.8 million, respectively [18]. Between 1951 and 2001, the population of Liverpool fell from 790,838 to 439,476 [19]. Leipzig experienced a similar decrease between 1933 and 2001, as the population declined from 713,470 to 493,052, and population density decreased from 5,548 to 1,657 inhabitants/km2 [20]. Facing this declining population and the underutilization of urban spaces, local governments have pursued urban redevelopment projects to create new uses for existing urban spaces [21]. This approach to address the problem of shrinking cities requires a more detailed consideration, as it is clearly a matter of increasing global concern.

1.3. Geographic Information System Urban planners need to evaluate comprehensive information for urban design. The results of GIS condition analyses enable planners to identify the sites most in need of innovation. Information evaluation, according to GIS, would be a crucial component of this planning method [22,23]. Building information, cartographic documentation, thematic maps, and on-site surveys were combined and evaluated, using the GIS, in an Italian study [24]. Building energy performance [25], health emergency analysis and planning [26], and detailed building typologies [27] have also been assessed, based on GIS. Sustainability 2019, 11, 1505 3 of 14

1.4. Geographic Condition Evaluation Sustainability 2019, 11, 1505 3 of 14 This study proposed the reduction of size and condensing the functions of cities, to solve a few social1.4. problems Geographic that Condition Japan Evaluation is currently facing. Efforts to cope with reduced utilization efficiency by reducingThis city study sizes proposed have not t beenhe reduc well-executed.tion of size and These condensing do represent the functions an important of cities, to aspect solve ofa few dealing withsocial our globally problems aging that society.Japan is currently This proposal facing should. Efforts beto qualifiedcope with toreduced meet theutilization special efficiency requirements by of olderreducing adults, whocity sizes tend have to retain not been a traditional well‐executed attitude. These toward do represent the streets an important which are aspect no longerof dealing suitable for inhabitation.with our globally Other aging newer society. elements This areproposal indispensable should be toqualified a sustainable to meet citythe planning,special requirements and these new elementsof older could adults evolve, who from tend traditional to retain a elements, traditional thus, attitude connecting toward the different streets wh generations.ich are no longer This study analyzedsuitable factors, for inhabi suchta astion plot. Other ratio, newer building elements type, are mixed indispensable commercial to a sustainable and residential city planning, spaces, and and the locationthese of new public elements facilities could for evolve older from adults. traditional elements, thus, connecting different generations. This study analyzed factors, such as plot ratio, building type, mixed commercial and residential 1.5. Urbanspaces, Shading and the Environmentlocation of public facilities for older adults.

The1.5. Urban purpose Shading of shrinkingEnvironment the city’s size is to concentrate its urban functions, and increase its building and population density, in order to increase urban efficiency. This concentration should be The purpose of shrinking the city’s size is to concentrate its urban functions, and increase its balancedbuilding with and urban population environmental density, in changes. order to Sunlightincrease urban conditions efficiency. and This shadows concentration from nearby should buildings be createbalanced an important with urban effect environmental on the passive changes. building Sunlight development, conditions as and sunlight shadows on southern from nearby exterior wallsbuildings obtains thecreate best an heatingimportant conditions effect on the in passive winters building [28]. Therefore, development, the as Building sunlight Standard on southern Law of Japanexterior established walls obtains a shadow the best restriction heating conditions to ensure in residential winters [28 zones]. Therefore, receive the sufficient Building Standard sunlight [29]. The sunlightLaw of Japan conditions established and a shadows shadow restriction from the surroundingto ensure residential buildings zones are rec importanteive sufficient issues sunlight to address during[29 the]. The urban sunlight redevelopment conditions and process. shadows These from the conditions surrounding should buildings be forecasted are important and issues evaluated to to regenerateaddress the during shrinking the urban cities. redevelopment process. These conditions should be forecasted and evaluated to regenerate the shrinking cities. 2. Research Methodology 2. Research Methodology In this study, we analyzed the existing conditions in a selected district, using urban information In this study, we analyzed the existing conditions in a selected district, using urban information and proposedand proposed a location a location for urbanfor urban concentration, concentration, based based on on a comprehensivea comprehensive assessment assessment ofof thethe site data. We obtaineddata. We population obtained population data from data the from government the government of Kitakyushu. of Kitakyushu. We inspected We inspected the current the current landform situationlandform and distributionsituation and of distribution livable facilities of livable in facilities the Yahatahigashi-ku in the Yahatahigashi district,‐ku by district, field byobservation. field We collectedobservation. and We synthesized collected and all synthesized data using all GIS. data As using shown GIS. inAs Figure shown1 in, Yahatahigashi-ku Figure 1, Yahatahigas districthi‐ is locatedku district between is located a mountain between and a themountain seacoast. and the seacoast.

FigureFigure 1. The 1. The location location of of the theYahatahigashi-ku Yahatahigashi‐ku district district (based (based on onGoogle Google Map Maps).s).

To forecastTo forecast shadow shadow conditions, conditions according, according to different urban urban planning planning methods methods in the in selected the selected regenerationregeneration area, area, we we used used Jw_cad, Jw_cad, which which isis aa JapaneseJapanese software software program program for forarchitects architects and andurban urban planners, designed to provide two- and three-dimensional drawings that forecast continuous shadow conditions in a single day [30]. Sustainability 2019, 11, 1505 4 of 14 plannersSustainability, designed2019, 11, 1505 to provide two‐ and three‐dimensional drawings that forecast continuous shado4 ofw 14 conditions in a single day [30].

2.1. The Selected District We selected the Yahatahigashi-kuYahatahigashi‐ku district in Kitakyushu, Japan, for this case study. Most of the areas in this district are mountainous, mountainous, with steep slopes. The The residential residential buildings were were built fforor employees during the period of Japan’s industrialization. From 1960 to 1970, Kitakyushu supported Japan’s rapid economic growth, by aggregating material material industries, industries, such such as as steel, steel, chemical, chemical, metal, metal, and ceramic industries. This This aggregation aggregation began began when when the the government government-managed‐managed Yahata Yahata Steelworks, Steelworks, the largest steelworks company in Asia, was founded in 1901. During that period, to accommodate employees, dwellings were constructed on the mountain,mountain, around the industrial area.area. Today, thethe materialmaterial industryindustry has movedmoved to otherother AsianAsian countries. High High-technology‐technology industries, industries, including industrial robots,robots, IC-relatedIC‐related products, products, and and biotechnologies, biotechnologies, are are generated. generated. The The retail retail areas areas in inthe the Yahatahigashi-ku Yahatahigashi‐ku district district are are in in decline, decline, as as the the number number ofof deserteddeserted houseshouses continues to incr increase,ease, and a new plan for urban regeneration is expected. The The proportion proportion of retirees has increased over the past 50 years, and most of the young people have been fleeing fleeing the city city,, due to the unsuitable living conditions. Young Young people people are moving to more comf comfortableortable residential environments, and and very few people are moving in in,, to this area. Thus, Thus, the the strategy strategy of of urban urban compactness compactness is is an an appropriate appropriate response response to address the decline. A A proper location for this urban concentration should be indicated,indicated, before beginnibeginningng the urban regeneration regeneration.. As shown in in Figure Figure 22,, steeplysteeply slopedsloped mountainous areasareas createcreate aa challenging livingliving environment because car access to these areas is non non-existent,‐existent, and and it it is difficult difficult for residents to carry out daily outdoor activities. As residen residentsts age age,, the inconvenient inconvenient geography makes it difficult difficult for them to access facilities near their homes. Older Older residents residents find find it hard to sustain the the necessary necessary effort effort to go to nursing nursing and shopping facilities facilities,, daily. The population scale, in in turn, turn, affects affects the the e efficiencyfficiency of of urban urban operations, operations, leading to wasted urban energy and compromised community safety. I Industrialndustrial trends have also changedchanged,, and the scale of factories havehave declined, increasing the possibility of developing flatflat areas.areas. The average average lifespan lifespan of of a Japanesea Japanese wood wood constructed constructed building building is about is 30 about years 30 [31 ]. years The dwellings[31]. The dwellingsin the Yahatahigashi-ku in the Yahatahigashi area‐ wereku area built were from built 1960 from to 1960 1970, to and1970, have and have already already been been in use in use for forabout about 50 years.50 years. Due Due to to a combinationa combination of of the the aging aging building building andand inconvenientinconvenient living environment, environment, some inhabitantsinhabitants havehave moved moved out, out, abandoning abandoning their their dwellings. dwellings Most. Most of the of residentsthe residents of the of high the slopes high slopesare willing are willing to move to out, move because out, because the area the is inconvenient area is inconveni for theirent changingfor their changing lifestyle, butlifestyle, many but remained many remainbecauseed they because cannot they afford cannot to buy afford an apartment to buy an somewhereapartment somewhere else. In the meantime, else. In the the meantime, local government the local governmentis trying to help is trying these toresidents. help these This residents case study. This provides case study suggestions provides to the suggestions local government to the local for governmentthe redevelopment for the of redevelopment the lower area ofof town,the lower which area would of provide town, which low-cost, would subsidized provide apartment low‐cost, subsidizedbuildings, forapartment this at-risk buildings population., for The this problems at‐risk faced population by the Yahatahigashi-ku. The problems existfaced throughout by the YahatahigashiJapan, as well‐ asku in exist other throughout industrial Japan countries,, as well and as the in approachother industrial to redevelopment countries, and discussed the approach in this topaper redevelopment might be of discussed use, beyond in this particularpaper might case. be of use, beyond this particular case.

Figure 2. ImagesImages of of the the residences residences on on the the steeply steeply-sloped‐sloped area. SustainabilitySustainability 20192019, ,1111, ,1505 1505 5 5of of 14 14 SustainabilitySustainability 20192019,, 1111,, 15051505 55 ofof 1414 2.2. The Development of the Slope Degree Method 2.2. The Development of the Slope Degree Method 2.2. TheTo evaluateDevelopment the steepnessof thethe Slope of Degree these Methodareas, we developed the slope degree method as a standard. To evaluate the steepness of these areas, we developed the slope degree method as a standard. For a Tomid evaluate‐ to large the‐scale steepness urban ofarea these, a 100 areas, m × we 100 developed m grid platform thethe slopeslope is commonlydegreedegree method used as to a reflect standard.standard. the For a mid- to large-scale urban area, a 100 m × 100 m grid platform is commonly used to reflect the buildingFor a mid environment‐‐ toto largelarge‐‐scalescale [32 ,urbanurban33]. The area variations,, aa 100100 mm in ×× height 100100 mm and gridgrid average platformplatform slope isis commonlycommonly for each 100 usedused m × to to100 reflectreflect m mesh thethe building environment [32,33]. The variations in height and average slope for each 100 m × 100 m mesh canbuilding be calculated environment by counting [[32,,33].]. the The number variations of contourin height lines and inaverage each mesh slope area, for each as shown 100 m ×in 100 Figure m mesh 3. can be calculated by counting the number of contour lines in each mesh area, as shown in Figure3. cancan bebe calculatedcalculated byby countingcounting thethe numbernumber ofof contourcontour lineslines inin eacheach meshmesh area,area, asas shownshown inin FigureFigure 3..

Figure 3. Definition of slope degree in each mesh. Figure 3. Definition of slope degree in each mesh. Figure 3. Definition of slope degree inin eacheach meshmesh.. By leveraging the overlapping mesh layer and contour line layer, as shown in Figure 4, we By leveraging the overlapping mesh layer and contour line layer, as shown in Figure4, we defined definedBy the leveraging slope degree the overlapping of each mesh. me Wesh then layer presented and contour the areas line layer,of the asmesh shown that inoverlapped Figure 4, the we the slopeBy leveraging degree of each the overlapping mesh. We then me presentedsh layer and the areas contour of the line mesh layer, that as overlapped shown in Figure the building 4, we buildingdefined thelayers slope and degree color‐ ofcoded each the mesh. slope We degree then presented for each building, the areas as of shown the mesh in Figure that overlapped 5. the layersdefined and the color-coded slope degree the of slope each degreemesh. We for then each presented building, asthe shown areas inof Figurethe mesh5. that overlapped the building layers and colorcolor‐‐codedcoded thethe slopeslope degreedegree forfor each building, as shown in Figure 5..

Figure 4. Image of overlapping layers. Figure 4. Image of overlapping layers. Figure 4.4. ImageImage ofof overlappingoverlapping layerlayerss.. By leveraging the overlapping mesh layer and contour line layer, as shown in Figure 4, we By leveraging the overlapping mesh layer and contour line layer, as shown in Figure4, we defined definedBy the leveraging slope degree the overlapping of each mesh. mesh We then layer presented and contour the areas line layer,of the asmesh shown that inoverlapped Figure 4, the we the slopeBy leveraging degree of each the overlapping mesh. We then mesh presented layer and the areas contour of the line mesh layer, that as overlapped shown in Figure the building 4, we buildingdefined thelayers slope and degree color‐ ofcoded each the mesh. slope We degree then presented for each building, the areas as of shown the mesh in Figure that overlapped 5. the layersdefined and the color-coded slope degree the of slope each degreemesh. We for then each presented building, asthe shown areas inof Figurethe mesh5. that overlapped the building layers and colorcolor‐‐codedcoded thethe slopeslope degreedegree for for each building, as shown in Figure 5..

Figure 5. Representation of the building slope degree (a slope degree of each mesh; b: layer overlapping; Figure 5. Representation of the building slope degree (a slope degree of each mesh; b: layer c: slope degree of each building). overlapping; c: slope degree of each building). Figure 5. Representation of thethe building slope degree ((aa slopeslope degree degree of of each each mesh; mesh; b:: layer layer overlapping; cc:: slopeslope degreedegree ofof eacheach building)building).. Sustainability 2019, 11, 1505 6 of 14

Sustainability 2019, 11, 1505 6 of 14 Slope degree represents the urban geographic characteristics and establishes the relationship Slope degree represents the urban geographic characteristics and establishes the relationship between urban information and buildings. This new standard can assist urban planners to better between urban information and buildings. This new standard can assist urban planners to better understand the nature of building layout, as they work to carry out building development plans understand the nature of building layout, as they work to carry out building development plans with with respect to . The advantage of this evaluation method is to visually present the respect to urban geography. The advantage of this evaluation method is to visually present the distribution of slope. Combining this urban information with the existing buildings could provide a distribution of slope. Combining this urban information with the existing buildings could provide a direct reference for related decision making. direct reference for related decision making. 2.3. Shadow Area Calculation and Comparison 2.3. Shadow Area Calculation and Comparison Building create shadows throughout the day. According to Article 56 of the Building Standard Law ofBuilding Japan, thecreate allowable shadows hours throughout of shadows the day. in different According land-use to Article zones 56 areof the indicated Building by Standard shadow restrictions,Law of Japan, to restrictthe allowable the building hoursheights of shadows for different in different neighborhoods. land‐use zones This are restriction indicated applies by shadow to all newly-constructedrestrictions, to restrict buildings the building and reconstructed heights for buildingsdifferent neighborhoods in Japan and can. This affect, restriction both, building applies height to all andnew placement.ly‐constructed These buildings shady conditions and reconstructed can be evaluated, buildings according in Japan to aand continuous can affect shadow, both, areabuilding that representsheight and the placement hours each. These day, duringshady conditions which the buildingscan be evaluated might cast, according shadows, to outside a continuous their respective shadow areas,area that as shown represents in Figure the hours6. The each standard day, during time for which environmental the buildings shadow might evaluation cast shadows is on, outside the winter their solstice,respective from areas, 8 am as toshown 4 pm. in OnFigure average, 6. The for standard residential time zones, for environmental 2-hour shadows shadow are evaluation restricted 10 is mon awaythe winter from buildings, solstice, from and 4-hour 8 am to shadows 4 pm. On are restricted average, for5 m residential away from zones, buildings 2‐hour [29]. shadows To compare are therestricted shady conditions10 m away between from buildings, the two urban and 4 regeneration‐hour shadows patterns, are restricted we used 5 Jw-cad m away to illustratefrom buildings the 2-, 3-,[29 and]. To 4-hour compare shadows the shad fory eachconditions plan. between the two urban regeneration patterns, we used Jw‐cad to illustrate the 2‐, 3‐, and 4‐hour shadows for each plan.

Figure 6. Explanation of continuous shadow area (a: hourly shadow area; b: continuous shadow area). Figure 6. Explanation of continuous shadow area (a: hourly shadow area; b: continuous shadow area). 3. Geographic and Population Information Analysis 3. Geographic and Population Information Analysis. 3.1. Urban Geographic 3.1. Urban Geographic The contour line with 2 m slope and building layout are presented in Figure7, which shows the relationshipThe contour between line with the 2 m urban slope geographyand building and layout buildings. are presented Factory in facilities Figure 7 are, which located shows in thethe beachrelationship areas, whereasbetween athe great urban number geograp ofhy dwellings and buildings. are on theFactory steeply-sloped facilities are area located of the in mountain. the beach Thisarea situations, whereas stems a great from number the industrial of dwellings age, during are on which the steeply time the‐sloped city grew area with of the a rapid mountain. population This increase.situation Astems sustainable from the urban industrial design age, is now during needed which to remediate time the thecity access grew methodswith a rapid for older population adults. increase. A sustainable urban design is now needed to remediate the access methods for older adults. Sustainability 2019, 11, 1505 7 of 14 Sustainability 2019, 11, 1505 7 of 14 Sustainability 2019, 11, 1505 7 of 14

FigureFigure 7. LandformLandform and and building building distribution distribution in in the Yahatahigashi Yahatahigashi-ku‐ku (2005).

Figure 88 showsshows thethe slopeslope degreedegree ofof eacheach buildingbuilding andand presentspresents thethe geographicgeographic environmentsenvironments inin which thethe buildingsbuildings are are located. located. The The higher higher the the slope slope degree, degree, the morethe more difficult difficult for the for people the people to access to accessthe urban the areas.urban Additionally,areas. Additionally, some buildings some buildings are situated are situated in an area in withan area a low with slope a low degree, slope at degree a high, atelevation; a high elevation; these buildings these arebuildings built on are the built flat areaon the of theflat mountain.area of the Inmountain. general, buildingsIn general, closer buildings to the closertop of to the the mountain top of the have mountain a higher have slope a higher degree. slope This degree. poor planningThis poor approachplanning approach has made has daily made life dailyinconvenient, life inconvenient for the residents, for the residents in this area. in this area.

Figure 8. Slope degree of each building. Figure 8. Slope degree of each building. 3.2. Urban Population 3.2. Urban Population Local activity creates a bustling community, while also improving a city’s atmosphere. Thus, Local activity creates a bustling community, while also improving a city’s atmosphere. Thus, the the populationLocal activity and creates construction a bustling both community affect local, while revitalization, also improving and a city’s should atmosphere. be analyzed Thus, before the population and construction both affect local revitalization, and should be analyzed before beginning populationbeginning theand urban construction planning both process. affect local As shown revitalization, in Figure and9, theshould population be analyzed density before of thebeginning towns the urban planning process. As shown in Figure 9, the population density of the towns situated on thesituated urban on planning the sloped process. area isAs lower shown than in thatFigure in the9, the flat population area, because density most of of the the towns dwellings situated on theon the sloped area is lower than that in the flat area, because most of the dwellings on the sloped area thesloped sloped area area are isolatedis lower houses.than that Recently, in the flat some area apartment, because most buildings of the were dwellings built closeon the to sloped the railway area are isolated houses. Recently, some apartment buildings were built close to the railway station. The arestation. isolated The houses. population Recently, in the some flat area apartment is increasing buildings slowly, were but built the close total to population the railway of station. this district The population in the flat area is increasing slowly, but the total population of this district continues to populationcontinues to in decrease, the flat area especially is increasing in the areas slowly, located but th one thetotal steeply-sloped population of areas. this district continues to decrease, especially in the areas located on the steeply‐sloped areas. Sustainability 2019, 11, 1505 8 of 14 Sustainability 2019, 11, 1505 8 of 14

Ocean

Figure 9. Population density of the Yahatahigashi-ku (2008). Figure 9. Population density of the Yahatahigashi‐ku (2008). As Figure 10 shows, most of the towns could be identified as having an “aging society” As Figure 10 shows, most of the towns could be identified as having an “aging society” (i.e., the (i.e.,As the Figure percentage 10 shows, of the most population of the towns over could 65 years be identified of age is as higher having than an “aging 25%). society” The percentage (i.e., the percentage of the population over 65 years of age is higher than 25%). The percentage of the ofpercentage the population of the that population is older than over 65 65 years years is of higher age is in higher the steeply-sloped than 25%). areas,The percentage which meets of the population that is older than 65 years is higher in the steeply‐sloped areas, which meets the standard standardpopulation of that a “limitative is older than colony” 65 years (i.e., is the higher percentage in the steeply of the‐ populationsloped areas, over which 65 years meets is the higher standard than of a “limitative colony” (i.e., the percentage of the population over 65 years is higher than 50%). As 50%).of a “limitative As seen in colony” Figure8 (i.e.,, these the areas percentage are situated of the along population the highly-sloped over 65 years areas is higher of the mountain.than 50%). As seen in Figure 8, these areas are situated along the highly‐sloped areas of the mountain. seen Thus,in Figure if current 8, these conditions areas are persist,situated the along population the highly will‐sloped continue areas to of decrease, the mountain. and the percentage Thus, if current conditions persist, the population will continue to decrease, and the percentage of elderlyThus, residentsif current willconditions continue persist, to increase. the populati Countermeasureson will continue should to decrease, be introduced and the to percentage this area, of elderly residents will continue to increase. Countermeasures should be introduced to this area, immediately, to maintain the vitality. immediately, to maintain the vitality. Ocean

Figure 10. Percentage of population older than 65 (2008). Figure 10. Percentage of population older than 65 (2008). 4. Urban Regeneration Based on GIS Analysis 4. Urban Regeneration Based on GIS Analysis 4.1. GIS Analysis 4.1. GIS Analysis Leveraging the analysis conducted on urban population (see Section3), using urban geographic data,Leveraging we created the an analysis encompassing conducted redevelopment on urban population plan to promote (see Section urban 3), vitality.using urban We proposedgeographic a data, we created an encompassing redevelopment plan to promote urban vitality. We proposed a migration from the sloped‐mountainous area to the flat area, to concentrate the population in this flat Sustainability 2019, 11, 1505 9 of 14

Sustainability 2019, 11, 1505 9 of 14 migration from the sloped-mountainous area to the flat area, to concentrate the population in this areaflat area,, to create to create a compact a compact city city center, center, thus thus,, promoting promoting a alivable livable community community.. We We identified identified the the area promoting inward migration, the area promoting outwar outwardd migration, and the buffer area area,, using the results through the GIS analysis, as shown in the Figure 1111. We We selected selected flat flat areas areas to to be the object region forfor inhabitantinhabitant migration. migration. The The migration migration is expectedis expected to concentrateto concentrate and and reduce reduce the citythe size,city thus,size, thusimproving, impro theving efficiency the efficiency of city of services city services and facilities. and facilities. AAreasreas promoting outward migration are those with high high slopes, slopes, high high ratios ratios of of elderly elderly residents, residents, elevations higher than 80 m, and slope slope degrees higher than 5. Residents Residents who who live live in in the the steeply steeply-sloped‐sloped areaareass should be encouraged to move. Areas promoting promoting inward inward migration migration are are flat flat and and offer offer convenient convenient traffic traffic and public and public facilities, facilities, with elevationswith elevations lower lowerthan 40 than m and 40 slope m and degrees slope lower degrees than lower 3. These than areas 3. These anticipate areas further anticipate enrichment further ofenrichment urban facilities of urban, to promote facilities, convenient to promote living. convenient living. Buffer areas are the areas between outward migration and inward migration areas. Government officesoffices and universities are currently situated in these areas. Areas of outward migration will become sparsely populated during during the the proc processess of inward migration. In In the the buffer buffer areas, areas, sparse sparse landscape, landscape, community decay, decay, and crime could be alleviated by adding public facilities and encouraging more human interaction. A high high density density of of population population and and buildings buildings are required are required to support to support the public the facilities public operation.facilities operationResidents. living Residents in areas living promoting in areas outward promoting migration outward currently migration cannot currently conveniently cannot conveniently access these accesspublic facilities, these public and these facilities, facilities and will these continue facilities to decay will as continue population to decay density as decreases. population Sustainable density decreases.urban planning Sustainable must urban condense planning these must city functionscondense andthese increase city functions population and increase density population to increase densityurban efficiency. to increase Some urban problems efficiency. make Some it difficult problems for inhabitants make it difficult to migrate for smoothly, inhabitants which to migrate include smoothlyeconomic, problemswhich include and local economic community problems conditions. and local Minimum community living conditions conditions. must Minimum be maintained living conditionsfor residents must who be need maint toained continue for livingresidents in the who areas need that to promotecontinue outward living in migration. the areas that promote outward migration.

Figure 11. ObjectObject region for inhabitant migration migration..

The central zone shown in Figure 1122 was a gateway into the residential area,area, through which employees would pass on on their way home from work. This was considered to be a high-levelhigh‐level commercial area in the past. Currently, Currently, the central zone includes a mix of of commercial commercial and residential residential areas. In In this this mixed mixed-use‐use area, area, all all necessary necessary city city facilities facilities are are located located within within 500 500 m m from from the the center, center, which is a reasonablereasonable distancedistance toto access access conveniently. conveniently This. This mixed-use mixed‐use area area has has the the potential potential to to serve serve as asa residential a residential area, area promoting, promoting inward inward migration. migration. Sustainability 2019, 11, 1505 10 of 14 Sustainability 2019, 11, 1505 10 of 14 Sustainability 2019, 11, 1505 10 of 14

Figure 12. The situation of public facilities. Figure 12. The situation of public facilities. 4.2. Environmental Shading and the Community Regeneration Plan 4.2.4.2. Environmental Environmental Shading Shading andand thethe CommunityCommunity Regeneration Plan By focusing on the area promoting inward migration (shown in Figure 12), the population capacityByBy focusing of focusing the built on on environment the the areaarea promoting promoting could be increased,inward migration providing ((shownshown more building in in Figure Figure facilities. 1 122)), , the theWe population population proposed capacitytwocapacity different of of the the redevelopment built built environment environment patterns could could to meet be the increased existing,, prov needsididinging and moremore create building building a more compact facilities. facilities. urban WWee proposedcenter.proposed With two two different thedifferent view redevelopment redevelopment of adapting new patterns building to meet facilities the existing into the needsneeds existing andand create create urban a a more more environment, compact compact urbanFigureurban center center13 compares. .With With the the two viewview plans—a ofof adaptingadapting composite newnew building regeneration facilities plan intointo and thethe existingexisting a partial urban urban regeneration environment, environment, plan. TheFigureFigure composite 1 133 compares compares regeneration twotwo plansplans plan——aa wouldcompositecomposite involve regeneration rebuilding plan whole andand a streeta partialpartial blocks regenerationregeneration with high-volume, plan. plan. The The compositemixed-use,composite regeneration regeneration high-rise buildings. plan plan wouldwould In this involveinvolve plan, rebuilding the lower partwhole of street the buildings blocksblocks with with would high high be‐‐volume,volume, for commercial mixed mixed‐‐ useuse, and,high high the‐rise‐rise upper buildingbuilding parts fors.. InIn residential thisthis plan,plan, orthethe office lowerlower use. part In of the thethe partial buildingsbuildings regeneration wwouldould bebe plan, forfor commercialeachcommercial street block use use wouldandand the the be upper upper partly partpart redeveloped, forfor residentialresidential according oror officeoffice to the use specific. In the land-use partialpartial regenerationregeneration ownership situation. plan,plan, eacheach streetstreet block block wouldwouldIn be ourbe partly partly proposed redeveloped redeveloped plan, each,, accoraccor newdingding apartment to the specific building land would‐‐use ownershipownership be 10 floors situationsituation tall. According. . to the redevelopmentInIn our our proposed proposed patterns, plan,plan, there eacheach would newnew beapartmentapartment 6–8 units building in the composite would bebe regeneration 1010 floorsfloors talltall plan,. . AccordingAccording or 4–6 unitsto to the the in redevelopmenttheredevelopment partial regeneration patterns, patterns, plan. therethere As wouldwould the average bebe 66–8 units number in the of composite inhabitants regenerationregeneration per family wasplan, plan, 2.47 or or 4 in4––66 2017units units [ 34in in], thethe partial total partial number regeneration regeneration of inhabitants plan.plan. AsAs for thethe each averageaverage building number would of inhabitants be 148–197, perper for familyfamily the composite was was 2.47 2.47 regenerationin in 201 20177 [ 34[34],] , plan,thethe total total or 98–148number number for of of the inhabitantsinhabitants partial regeneration forfor eacheach building plan; this would would be 148 fully––197197 support,, forfor thethe efficient compositecomposite operation regeneration regeneration of local publicplan,plan, or or transportation. 98 98––148148 for for the the partialpartial regenerationregeneration plan; this would fullyfully supportsupport efficientefficient operation operation of of local local publicpublic transportation. transportation.

Figure 13. The image of the two regeneration plans (a: composite regeneration plan; b: partial FigureFigure 13. 13. TheThe image image of of thethe twotwo regeneration regeneration plans (a:: composite composite regeneration regeneration plan; plan; bb: : partial partial regeneration plan). regenerationregeneration plan) plan). . In the composite regeneration plan, the building layout in the core area would be completely In the composite regeneration plan, the building layout in the core area would be completely redeveloped.In the composite The urban regeneration form could, plan, thus, the be building unified, layout within in all the blocks. core Inarea the would partial be regeneration completely redeveloped. The urban form could, thus, be unified, within all blocks. In the partial regeneration plan,redeveloped. the demolition The urban and form redevelopment could, thus of, be the unified existing, within buildings all blocks. could beIn carriedthe partial out, regeneration according to plan,plan, the the demolition demolition andand redevelopmentredevelopment of the existing buildingss couldcould bebe carriedcarried out out, ,according according to to thethe individual individual conditions conditions forfor eacheach locationlocation,, andand some of the existing buildingsbuildings would would be be maintained. maintained. Sustainability 2019, 11, 1505 11 of 14

theSustainability individual 2019 conditions, 11, 1505 for each location, and some of the existing buildings would be maintained.11 of 14 Compared to the existing low-rise blocks with narrow streets, the redeveloped plans with the high-rise buildingsCompare wouldd to the create existing smaller low‐ buildingrise blocks footprints, with narrow larger streets, building the setbackredevelop fromed theplans streets, with andthe high wider‐ streets.rise buildings This would would provide create smaller a greater building availability footprint of urbans, larger green building surfaces, setback which from would the streets, potentially and reducewider the streets. energy This consumption would provide for thea greater lower partsavailability of the buildingsof urban and green promote surfaces, a healthier which would urban microclimatepotentially reduce [35,36]. the energy consumption for the lower parts of the buildings and promote a healthierFigure urban 14 shows microclim the resultsate [35,36 of]. the shady condition estimation, for the two regeneration plans. AccordingFigure to 14 Japanese shows the regulations results of (asthe discussedshady condition above), estimation 4-hour shadows, for the two are restrictedregeneration 5 m plans. away fromAccording buildings, to Japanese on the regulations winter solstice, (as discussed in residential above), districts, 4‐hour shadows and the are presence restricted of 5 such m away shadows from increasesbuildings the, on likelihood the winter of solstice opposition, in residential to the redevelopment districts, and plan,the presence within theof such local shadows community. increases In the partialthe likelihood regeneration of opposition plan, almost to the all redevelopment buildings remain plan in, within poor sunlight the local conditions, community. and In somethe partial are in 4-hourregeneration shadow. plan, Inthe almost composite all buildings regeneration remain plan, in poo veryr sunlight few buildings conditions, experience and some a 4-hour are in shadow.4‐hour Comparedshadow. In with the the composite partial regeneration plan, verythe composite few buildings regeneration experience plan a 4 created‐hour shadow. superior sunlightCompared conditions, with the with partial fewer regeneration shady areas. plan, the composite regeneration plan created superior sunlight conditions, with fewer shady areas.

FigureFigure 14. 14. ShadeShade conditionsconditions for the the twotwo regeneration regeneration plans on the winter solstice ( a:: composite composite regenerationregeneration plan; plan;b b:: partial partial regenerationregeneration plan).plan). 5. Discussion 5. Discussion To address the current aging society in Japan, this case study combined a variety of data to suggest To address the current aging society in Japan, this case study combined a variety of data to two potential urban redevelopment plans, to promote urban activity and improve the efficiency of suggest two potential urban redevelopment plans, to promote urban activity and improve the urban service facilities. Urban planners must find the most suitable area to arrange concentrated efficiency of urban service facilities. Urban planners must find the most suitable area to arrange land use, throughout the planning process. Sustainable urban design requires that new elements be concentrated land use, throughout the planning process. Sustainable urban design requires that new introducedelements be into introduced traditional into configurations, traditional configurations, while the construction while the style construction of buildings style in of a mixed-usebuildings in area, a canmixed better‐use reflect area, the can character better reflect of a district. the character This case of a study district. for theThis revitalization case study for of thethe Yahatahigashi-kurevitalization of canthebe Yahatahigashi applied to redevelopment‐ku can be applied projects, to redevelopment in other shrinking projects cities., in other shrinking cities. ThisThis studystudy developeddeveloped and and standardized standardized the slope-degreeslope‐degree method, method, using using GIS GIS data data as as a a developmentdevelopment tool,tool, and identified identified the the importance importance of ofgeographic geographic information information for urban for urban planning. planning. The Themethod method for calculating for calculating slope slope degree degree used usedin this in paper this paper was not was the not only the way only to way obtain to obtainurban slope urban slopeconditions, conditions, and andmore more effective effective calculation calculation method methodss should should be be studied studied in in the the future. future. This This pape paperr highlightedhighlighted the the importance importance ofof sharingsharing datadata evaluations,evaluations, throughout the urban planning process. process. AfterAfter thethe departuredeparture ofof thethe inhabitants,inhabitants, empty houses on the high slope slope areas areas would would become become witnesseswitnesses toto the history history of of Yahatahigashi Yahatahigashi-ku’s‐ku’s boom boom years years,, as a as well a‐ well-developeddeveloped industrialized industrialized city. city.As with As withsimilar similar sites sitessuch suchas Japan’s as Japan’s Battleship Battleship Island Island in Nagasaki, in Nagasaki, and the and Yokohama the Yokohama Red Brick Red BrickWarehouse, Warehouse, the unique the unique mountainous mountainous landscape landscape of Yahatahigashi of Yahatahigashi-ku‐ku has the potential has the potentialfor tourism for tourismplanning. planning. ThisThis casecase study study proposed proposed and and compared compared two twoideal ideal plans plansfor community for community regeneration. regeneration. Urban Urbanredevelopment redevelopment usually usually requires requires significant significant time, so time, that so plans that canplans be can negotiated be negotiated with the with local the localcitizens. citizens. The Theredevelopment redevelopment of inward of inward migration migration promotion promotion areas areas requires requires the the agreement agreement of of all all landownerslandowners of of each each existing existing dwelling, dwelling which, which is oneis one of the of mostthe most time-consuming time‐consuming aspects aspects for most for urbanmost urban redevelopment cases in Japan. Therefore, the composite regeneration plan that redevelops the whole block, would be more difficult to carry out in reality, than the partial regeneration plan. Future Sustainability 2019, 11, 1505 12 of 14 redevelopment cases in Japan. Therefore, the composite regeneration plan that redevelops the whole block, would be more difficult to carry out in reality, than the partial regeneration plan. Future studies should consider the different policies on urban redevelopment and demolition compensation measures.

6. Conclusions In this paper, we used GIS for site analyses, developed an urban geographic evaluation standard for slope degree, and discussed a proposed urban regeneration plan for the Yahatahigashi-ku, as a case study. The GIS evaluation of the Yahatahigashi-ku revealed that many dwellings in the highly-sloped mountainous areas, created poor living conditions for the older adults. Poor urban planning forced inhabitants to walk everywhere, due to limited vehicular access in the steeply-sloped areas, making it difficult for the older adults who form a high proportion of Yahatahigashi-ku’s population. A GIS evaluation, enabled planners to propose methods for urban regeneration that would require the concentration of city functions, the connection of access points for public facilities, and the improvement of the residential environment. Most of the young people are moving out of the area, and older adults stay back because they cannot afford to move elsewhere. This study suggests that the government provide financial support to the local people for urban regeneration. It was crucial to introduce GIS, to redesign a suitable site for local migration. In this comprehensive evaluation, we selected the central zone as the ideal site for redevelopment, considering the urban and built environment through the redevelopment process. The environmental evaluation of two community regeneration plans demonstrated that a composite regeneration plan created better sunlight conditions. It is imperative that city planners conduct an evaluation of site information to identify the most suitable area for planning, based on the satisfaction of current residents within their environment. The formulation of a sustainable urban design requires that new elements be introduced into the traditional configuration, especially as the construction styles of buildings in mixed-use areas, reflect the character of each district. This study provides insight into urban redevelopment for shrinking cities in Japan, based on the evaluation of the urban population, geography, and environment. This case study contributes to the literature on urban renovation in Japanese cities, as well as in other cities facing similar situations.

Author Contributions: H.F. and Y.W. contributed equally to this paper. They performed the experiments, analyzed the data, and wrote the paper together. Funding: This research was funded by the Department of Housing & Urban–Rural Development of the Shaanxi Province China, grant number 2016-RJ17. Conflicts of Interest: The authors declare no conflict of interest.

References

1. Oswalt, P. Volume 1: International Research. In Shrinking Cities; Hatje Cantz: Ostfildern-Ruit, Germay, 2005. 2. Lee, J.; Newman, G. Forecasting Urban Vacancy Dynamics in a Shrinking City: A Land Transformation Model. ISPRS Int. J. Geo-Inf. 2017, 6, 124. 3. Grekousis, G.; Mountrakis, G. Sustainable development under population pressure: Lessons from developed land consumption in the conterminous US. PLoS ONE 2015, 10, e0119675. [CrossRef][PubMed] 4. United Nations, Department of Economic and Social Affairs, Population Division. Ageing 2013; ST/ESA/SER.A/348; United Nations: New York, NY, USA, 2013. 5. World Health Organization (WHO). Global Age-Friendly Cities: A Guide, World Health Organization: Geneva, Switzerland, 2007. 6. World Health Organization (WHO). World Health Statistics 2016. Available online: http://www.who.int/ gho/publications/world_health_statistics/2016/en/ (accessed on 1 November 2018). 7. National Institute of Population and Social Security Research (Japan). Social Security in Japan. 2014. Available online: http://www.ipss.go.jp/s-info/e/ssj2014/PDF/ssj2014.pdf (accessed on 15 April 2017). 8. Pallagst, K. Shrinking Cities—Planning Challenges from an International Perspective. Urban Infill, Themenheft— Cities Growing Smaller; Kent State University: Cleveland, OH, USA, 2008; pp. 6–16. Sustainability 2019, 11, 1505 13 of 14

9. Martinez-Fernandez, C.; Audirac, I.; Fol, S.; Cunningham-Sabot, E. Shrinking cities: Urban challenges of globalization. Int. J. Urban Reg. Res. 2012, 36, 213–225. [CrossRef][PubMed] 10. Swyngedouw, E. Globalisation or glocalisation? Networks, territories and rescaling. Camb. Rev. Int. Aff. 2004, 17, 25–48. [CrossRef] 11. Gereffi, G. The global economy: Organization, governance, and development. In The Handbook of Economic Sociology, 2nd ed.; Smelser, N.J., Swedberg, R., Eds.; Princeton University Press and the Russell Sage Foundation: Princeton, NJ, USA, 2005. 12. Martinez-Fernandez, C.; Wu, C.T. Stadtenwicklung in einer differenten Wirklichkeit. Schrumpfende Städte in Australien. Berl. Debatte Initial 2007, 1, 45–60. 13. Bontje, M. Facing the challenge of shrinking cities in : The case of Leipzig. Geojournal 2004, 61, 13–21. [CrossRef] 14. Organization for Economic Co-operation and Development (OECD). Compact City Policies (Japanese Version): A Comparative Assessment; OECD: Paris, France, 2012. 15. Ministry of Land, , Transport and Tourism (MLIT). Population Reduction and the Land Use (Japanese Version); 28 January 2016. Available online: http://www.mlit.go.jp/common/001120157.pdf (accessed on 20 January 2019). 16. Rybczynski, W.; Linneman, P.D. How to Save our Shrinking Cities; Public Interest: Boca Raton, FL, USA, 1999; p. 30. 17. United Nations Population Estimates and Projections. World Population Review. Available online: http://worldpopulationreview.com (accessed on 10 November 2018). 18. Couch, C.; Karecha, J.; Nuissl, H.; Rink, D. Decline and sprawl: An evolving type of urban development– observed in Liverpool and Leipzig. Eur. Plan. Stud. 2005, 13, 117–136. [CrossRef] 19. Couch, C. City of Change and Challenge: Urban Planning and Regeneration in Liverpool; Ashgate Publishing: Aldershot, UK, 2004. 20. Nuissl, H.; Rink, D. and Post-Socialist Transformation: The Case of Leipzig (Germany); UFZ Centre for Environmental Research, Department of Economics, Sociology and Law: Leipzig, Germany, 2003. 21. Mulligan, H. Environmental Sustainability Issues for Shrinking Cities: US and Europe. In Shrinking Cities, International Perspectives and Policy Implications; Pallagst, K., Wiechmann, T., Martinez-Fernandez, C., Eds.; Routledge: Abingdon, UK, 2014; pp. 279–302. 22. Bloom, D.E.; Canning, D.; Fink, G. and the wealth of nations. Science 2008, 319, 772–775. [CrossRef][PubMed] 23. Grekousis, G.; Manetos, P.; Photis, Y. Modeling urban evolution using neural networks, fuzzy logic and GIS: The case of the Athens . Cities 2013, 30, 193–203. [CrossRef] 24. Dall’O’, G.; Galante, A.; Torri, M. A methodology for the energy performance classification of residential building stock on an urban scale. Energy Build. 2012, 48, 211–219. [CrossRef] 25. Dascalaki, E.G.; Droutsa, K.G.; Balaras, C.A.; Kontoyiannidis, S. Building typologies as a tool for assessing the energy performance of residential buildings—A case study for the Hellenic building stock. Energy Build. 2011, 43, 3400–3409. [CrossRef] 26. Grekousis, G.; Photis, Y. Analysing high-risk emergency areas with GIS and neural networks: The case of Athens Greece. Prof. Geogr. 2014, 66, 124–137. [CrossRef] 27. Loga, T.; Diefenbach, N.; Stein, B.; Balaras, C.A.; Villatoro, O.; Wittchen, K.B. Typology Approach for Building Stock Energy Assessment. In Main Results of the TABULA Project; European Commission: Darmstadt, Germany, 2012. 28. Yang, L.; He, B.J.; Ye, M. Application research of ECOTECT in residential estate planning. Energy Build. 2014, 72, 195–202. [CrossRef] 29. Hasegawa, T. Introduction to the Building Standard Law-Building Regulation in Japan. 1-212; Building Center of Japan: Tokyo, Japan, 2013. 30. Shimizu, J.; Tanaka, Y. Jw_cad. Available online: www.jwcad.net/ (accessed on 15 November 2017). 31. Komatsu, Y.; Kato, Y.; Yoshida, T.; Yashiro, T. Report of an Investigation of the Life Time Distribution of Japanese House at 1987—Estimation based on the ledgers of buildings for fixed property taxes. J. Archit. Plan. Environ. Eng. 1992, 439, 101–110. 32. Jiang, F.; Liu, S.; Yuan, H.; Zhang, Q. Measuring urban sprawl in Beijing with geo-spatial indices. J. Geogr. Sci. 2007, 17, 469–478. [CrossRef] Sustainability 2019, 11, 1505 14 of 14

33. Miao, S.; Jiang, W.; Wang, X.; Guo, W. Impact assessment of urban meteorology and the atmospheric environment using urban sub-domain planning. Bound. Layer Meteorol. 2006, 118, 133–150. [CrossRef] 34. Ministry of Health, Labour and Welfare (MHLW). Baseline Survey of National Life on 2017 (Japanese Version). Available online: https://www.mhlw.go.jp/toukei/saikin/hw/k-tyosa/k-tyosa17/index.html (accessed on 20 January 2019). 35. Akbari, H.; Pomerantz, M.; Taha, H. Cool surfaces and shade trees to reduce energy use and improve air quality in urban areas. Sol. Energy 2001, 70, 295–310. [CrossRef] 36. Wang, Y.; Berardi, U.; Akbari, H. Comparing the effects of mitigation strategies for Toronto, Canada. Energy Build. 2016, 114, 2–19. [CrossRef]

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