This study aims to examine the cutting traces remaining on the bracket tie beams of Sungnyemun gate, identifying the tools employed during the late Goryeo to early Joseon periods by specific processes, and deliberating on the timber shaping techniques utilized in advanced architectural construction during the late Goryeo to early Joseon eras. Through the research, it was confirmed that in the production of Sungnyemun Gate's bracket tie beams during the 14th to 15th centuries, both the timber splitting and ripsawing methods were used in conjunction. Moreover, the wood finishing process revealed the use of a plane. It can be inferred that the characteristics of the plane used during that time were not significantly different from those observed in the later period of the Joseon dynasty. The ripsawing and plane finishing techniques were evident in various parts of the bracket tie beams of Sungnyemun gate across the reigns of king Taejo and Sejong, indicating that the techniques involving ripsaw and plane were already prevalent in the late Goryeo period. Consequently, it can be inferred that the ripsawing and plane finishing techniques might have been applied in the construction of prominent government buildings in Hanyang(Seoul), including Gyeongbokgung Palace, and in the residences of royalty and nobility after the establishment of the Joseon dynasty.

This article focuses on the Namdaemum repair and the Seokguram restoration, which had begun in 1961, as an important repair conducted during the time of seeking the conservation principle of architectural heritage after liberation in Korea. Through the analysis of the principles described in the repair report issued after the two repairs, meeting records, and related expert announcements, it is shown that the principle of 'preservation of the historic state' had been established at Namdaemun repair and later have changed to the principle of 'restoration of the historic form' which means reconstruction in Seokguram restoration. By analyzing the minutes of the Cultural Heritage Committee's meeting on the repair of other cultural properties during this period, it is revealed that the key terms related to the preservation principle, 'historic form' and 'restoration', were given meaning as 'object' and 'method' of preservation, and then 'restoration of the historic form' has been gradually used as a conservation principle.

본 논문에서는 전통 목조건축물로 되어 있는 대한민국의 국보 1호인 숭례문의 구조해석을 수행하고 안전도를 평가하였다. 전통 목조건축의 대부분의 하중을 차지하고 있는 숭례문의 지붕하중을 상세히 산정하고 숭례문의 가구구성 특징을 면밀히 살펴 범용 구조해석 소프트웨어인 midas Gen으로 구조해석모델을 구축하였다. 수직하중에 대한 정적구조해석을 수행하고 주요 수직 수평 구조부재의 안전성과 주요 수평부재의 사용성을 평가하였다. 숭례문의 동적거동특성을 평가하기 위하여 현장에서의 충격해머실험과 구조해석 소프트웨어를 이용한 고유치해석을 수행하고 그 결과를 비교하고 주요모드를 도출하였다. 수직하중에 대한 검토결과 숭례문은 구조적 능력에 여유가 있는 것으로 나타났다.

The purpose of this research is to analyse the changes of ground level of Sungnyemun, the South Gate of Seoul City, and the principles of arch scale through the investigation based on the old records in Joseon dynasty. The result of this research is as follows: 1) The ground level of Sungnyemun, refers the level of foundation stone which was confirmed as original which is verified through the excavation conducted in 2005, maintained 1m's elevated level in 15～16 century and its elevated date presumed in King Sejong's reign(1418～1450). 2) The ground level of Sungnyemun is closely related with the royal funeral ceremony. 3) The width and height scale of Sungnyemun arch is about the ratio of 1 to 1. 4) During the Joseeon dynasty, Sungnyemun was referred as standard of other city wall gate. And it has similar architectural characteristics with Heunginjimun (or East Gate) of Seoul and Hwaseong Janganmun.

This research work is to analyze architectural characteristics of Sungnyemun especially in King Yeongjo's reign in Joseon dynasty. The result of this research is summarized as following: 1. The architectural characteristics of Sungnyemun in King Yeongjo's reign are closely related with Confucian ceremonies such as Jeon-jwa and Heon-goek-rye. To perform these ceremonies, some lower walls of Sungnyemun's wooden pavilion were removed and used as ceremonial space. And after ceremony it was restored. 2. The floor type of center bay of the 1st story of wooden pavilion should have a type of floor using long and narrow fine tree plate, which is same type before the repair work of 1960's dismantlement. 3. The width of east stairway which is reached to east small gate, was changed just before Japanese's rule(1910～1945), should be broaden than present width, which is proven through the recent excavation. 4. The reason of asymmetric characteristic of locations of both east and west narrow-gate, and widths of east and west stairway, are related with order of King's ceremony.

The Sungnyemun roofing tiles were twice disassembled for maintenance work, in 1963 and 1997, and modern tiles were applied in 1997. However, besides differing in visual appearance, the modern tiles had distinctly different physical properties. A study has been carried out on 22 different tiles, including original Sungnyemun tiles, modern tiles applied during maintenance, traditional tiles made by tile-makers, and others, to examine their physical properties, such as bending strength, frost resistance, absorption, whole-rock magnetic susceptibility, chromaticity, differential thermal analysis, and other characteristics. Since the method of making modern tiles involves compressing clay in a vacuum, modern tiles showed relatively greater bending strength and specific gravity, while Sungnyemun tiles and those made by tile-makers, in comparison, demonstrated less bending strength and specific gravity owing to their production method of 'treading,' in which clay is mixed by having someone tread upon it repeatedly. Over time, the absorption rate of the original tile used for Sungyemun gradually decreased from 21% to 14.7%; traditional tiles from tile-makers showed absorption rates of 17%, while the absorption rate of modern tiles was just 1%, which is significantly low. As for frost resistance, Sungnyemun tiles and traditional tiles from tile-makers showed cracking and exfoliation after being subjected to testing 4 or 5 times, while slight cracking was seen on the surface for modern tiles after 1ngy, or 3 times. In other words, no significant difference from influence by frost was found. According to the results of differential thermal analysis, the plastic temperature was shown to have been no less than 1, on℃ for all types of tile, and cristobalite was measuredthrough XRD analysis from a Sungnyemun female tile applied during maintenance in 1963, which appeared to have been plasticized at between 1,200℃~1,300℃. Based on these research results on the physical properties of tiles from the Sungnyemun roof, a fundamental production method for tiles to be applied in the restoration of Sungnyemun has been identified.

국보 1호인 숭례문 화재는 화재조사자뿐만 아니라 국민들에게 크나큰 아픔을 안겨 주었다. 이 연구의 목적은 현장조사를 통하여 목조 문화재 화재 시 생성되는 연소패턴과 목재 마루바닥에 인화성물질을 살포 후 착화하였을 때 나타나는 촉진제에 의한 연소 흔적 등을 확인하는데 있다. 또한 이 연구결과는 유사한 화재 발생 시 화재조사요원에게 정확한 화재 원인을 감식할 수 있는 자료가 될 것이다.

The mechanical properties of stone structures are generally characterized according to the strength of the stone used. An ultrasonic velocity method that does not damage cultural heritages is used to measure the strength of stone. However, there is no correction involved for surface roughness and thickness of the stone in the ultrasonic method currently used. In addition, a contact agent such as grease can cause contamination on the surface of a cultural heritage.