sustainability Article The Evolutionary Use of Curved Wood in Korean Traditional Architecture Seong Lyong Ryoo and Hyun Chul Youn * Department of Architecture, Korea University, Anam-ro 145, Seoul 136-713, Korea; [email protected] * Correspondence: [email protected]; Tel.: +82-10-7126-1956 Received: 5 November 2019; Accepted: 13 November 2019; Published: 20 November 2019 Abstract: Various types of curved wooden have always been used in traditional Korean architecture. One component is a curvaceous column with varying thicknesses, and the others are curved beams or girders that are needed to support the roof and present diverse curvature. By examining the historical alteration of the parts and shapes of these curved members, it is possible to identify the sustainable aspects of Korean traditional architecture and infer the influence of the historical background on forming the sustainability of the architecture. To be specific, while the Goryeo Dynasty (10–14 C) showed an aesthetic summit of temple architecture in terms of extravagant curved wooden members precisely calculated and designed under the influence of Buddhism and aristocracy, the early Joseon Dynasty (15–16 C) presented restrained curve forms of wooden members with fewer materials and a faster process due to Neo-Confucianism, which emphasized austerity. After tremendous social crisis and two wars, the mid-Joseon Dynasty (17–18 C) showed creative indigenous houses with naturally curved timbers, minimizing the manufacturing process and maximizing the pragmatic functionality of the space under the influence of the wars and Silhak (the Realist School of Confucianism). In addition, the late Joseon Dynasty (19–20 C) presented office buildings with strengthened dynamic shapes of the naturally curved timbers as symbolic expression, which is an expanded concept beyond the functionality. In Korean traditional architecture, curved wood members have been used without interruption—although in varying degrees depending on social and economic situations—and have continued to be one of the characteristics of Korean architecture. Keywords: curved wooden members; restrained curve forms; naturally curved timbers; functionality; symbolic expression 1. Introduction Korea has a long history of wood architecture. The term ‘adaptable to nature’ tends to be a common modifier to express the characteristics of Korean traditional architecture [1]. For Korean cases, the concept of convergence and harmony with nature [2] has also been emphasized to describe the very nature of Korean traditional wooden buildings. It is true that Korean wood architecture has uniquely evolved, in a way adapting and revealing the materiality of wood. While they share some common features over time, the wooden structures have different ideas and styles according to the time, as shown between those of the Goryeo (10–14 C) and Joseon (15–20 C) Dynasties [3]. The differences between the times have been also manifested in paintings, crafts, and many other artworks as well. Perhaps, pottery is among the most notable examples to understand the differences. A Korean daily newspaper once ran an advertisement of an exhibition containing a picture of Goryeo celadon and Joseon white porcelain, which effectively showed the different aesthetics of the different times (Figure1). While the Goryeo celadon shows elaborate and splendid expression in symmetrical form, the Joseon white porcelain presents simple and plain aspects with asymmetrical proportion. The Sustainability 2019, 11, 6557; doi:10.3390/su11236557 www.mdpi.com/journal/sustainability Sustainability 2019, 11, x FOR PEER REVIEW 2 of 16 Sustainability 2019, 11, 6557 2 of 16 form, the Joseon white porcelain presents simple and plain aspects with asymmetrical proportion. The expressional differences of form come from various factors such as religion, ideology, expressional differences of form come from various factors such as religion, ideology, international international relations with the adjacent countries, and collective public tastes of the time [4]. relations with the adjacent countries, and collective public tastes of the time [4]. (a) (b) Figure 1. (a) Goryeo celadon; (b) Joseon white porcelain. (Source: DonA Ilbo Article 2019.7.1). Figure 1. (a) Goryeo celadon; (b) Joseon white porcelain. (Source: DonA Ilbo Article 2019.7.1). Similar to the craft fields, this research attempts to verify that the period of Korean traditional architectureSimilar canto the be dividedcraft fields, by certainthis research noticeable attempts architectural to verify elements that the of period the buildings. of Korean In traditional particular, thearchitecture research focusescan be divided on the curve-shapedby certain noticeable wooden architectural members of elements Korean traditional of the buildings. architecture, In particular, which havethe research not only focuses universality on the curve-shaped but also diversity wooden of the members times from of Korean Goryeo traditional to Joseon. architecture, Scrutinizing which the historicalhave not only alteration universality of the curved but also wooden diversity members, of the times this research from Goryeo tries toto reveal Joseon. that Scrutinizing the change the of thehistorical parts andalteration shapes of of the the curved members wooden are critical members, evidences this research of the sustainability tries to reveal of Koreanthat the traditional change of architecturethe parts and reflecting shapes of the the social member ands cultural are critical background evidences of of the the era. sustainability of Korean traditional architecture reflecting the social and cultural background of the era. 2. Materials and Methods 2. Materials and Methods 2.1. Materials 2.1. MaterialsThe research subjects are chosen among the listed buildings that contain curved or bent wooden membersThe research of the framework. subjects are Especially, chosen among it is limitedthe listed to buildings the buildings that ofcontain designated curved national or bent wooden cultural propertiesmembers of in the Korea. framework. Since they Especially, are under it strict is limited national to the level buildings management, of designated they, as objective national researchcultural sources,properties are in credible Korea. Since to retain they theirare under appearance strict na attional the timelevel ofmanagement, construction they, and as are objective recognized research as a representativesources, are credible example to ofretain the eratheir in historical,appearance academic, at the time and of artistic construction aspects. and are recognized as a representativeThere are severalexample Goryeo-era of the era buildingsin historical, that academic, still remain and in artistic Korea, includingaspects. Andong Bongjeongsa GeukrakjeonThere are in several the 10th Goryeo-era century [5 ],buildings the oldest that wooden still remain building in in Korea, Korea, including Yeongju BuseoksaAndong MuryangsujeonBongjeongsa Geukrakjeon in the 11th in century the 10th [6 century], and Yaesan [5], the Sudeoksa oldest wooden Daeungjeon building in 1308in Korea, [7]. Yeongju Most of themBuseoksa are Buddhist Muryangsujeon temple buildings,in the 11th whichcentury also [6], include and Yaesan Yeongju Sudeoksa Buseoksa Daeungjeon Josadang andin 1308 Yeongcheon [7]. Most Eunhaesaof them are Geojoam Buddhist Yeongsanjeon. temple buildings, If it is not which a temple, also theinclude main Yeongju gate of Gangneung Buseoksa Josadang Gaeksa is oneand ofYeongcheon the Goryeo-era Eunhaesa buildings Geojoam we can Yeongsanjeon. still witness [If8 ].it Comparedis not a temple, to the the Goryeo main Dynasty, gate of manyGangneung more Joseon-eraGaeksa is one buildings of the Gory remain.eo-era In buildings terms of thewe purposecan still witness of building, [8]. Compared for instance, to the many Goryeo more Dynasty, types of Joseon’smany more buildings Joseon-era have buildings been left, remain. including In terms palaces, of the housings, purpose educational of building, facilities, for instance, and villas, many whilemore Goryeo’stypes of Joseon’s consist merelybuildings of thehave Buddhist been left, temples including and governmentpalaces, housings, buildings. educational Therefore, facilities, due to and the largevillas, number while Goryeo’s and variety, consist it ismerely relatively of the easy Buddhist to group temples the buildings and government of Joseon buildings. Dynasty Therefore, into three periods:due to the the large early, number middle, and and variety, latter. it is relatively easy to group the buildings of Joseon Dynasty into three periods: the early, middle, and latter. 2.2. Methods 2.2. MethodsThe research is conducted by site visit and data analysis from the collected historical records. Figure2 shows the specific locations of the research cases with the map of South Korea. After classifying The research is conducted by site visit and data analysis from the collected historical records. the periods of the traditional buildings, it shows that there are certain typical curved wooden members Figure 2 shows the specific locations of the research cases with the map of South Korea. After that represent a particular period. For example, Umiryang (cow-tail-shaped beam, interconnects classifying the periods of the traditional buildings, it shows that there are certain typical curved purlins with different levels in the form of steps) was used from the Goryeo Dynasty to the early Joseon wooden members that represent a particular period. For example,