• Journal of Conservation Science
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• v.35 no.5
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• pp.480-493
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• 2019

In this study, the method for processing glue and glue-alum sizing from the dancheong ground treatment was evaluated with respect to weather resistance, and its effect on the conservation of dancheong was analyzed. Viscosity and pH of the glue and glue-alum specimen were measured and classified into three categories(none layer, glue layer, and glue-alum layer), which were further classified according to low concentration(four times for 2%) and high concentration(once for 10%). The base layer formation was subsequently classified into three categories based on pigment adoption, namely, Noerok(celadonite), Seokganju(terra rossa), and Jangdan(red lead). The completed specimen was subjected to a changing-environment experiment for evaluating weather resistance and observing the surface. Color variations were analyzed before and after the experiment. The results indicate that glue-alum sizing comprising 5% alum or 7% alum has strong acidity that can affect the life of dancheong, and the high level of 7% alum makes it difficult to create a solid coating layer. After ultraviolet irradiation, the specimen with 7% alum changes its color to yellow. Furthermore, after moisture absorption and drying, cracks can be observed on the entire specimen surface that corroborate the physical change. Additionally, gas-based corrosion causes marginal surface changes. Hence, the formation of a stable coating layer can be achieved by incorporating a low concentration glue solution that is almost neutral, and the application of glue-alum sizing having 2% concentration can aid in the conservation of dancheong.

• Korean Journal of Heritage: History & Science
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• v.54 no.1
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• pp.4-17
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• 2021

This study analyzed 19 samples of harness fittings and pendants, which were excavated in Tomb No. 15 in Songhyeon-dong, Changnyeong. Harness fittings and pendants are used for ostentation, rather than practicality, and were excavated from ancient tombs in Gaya culture. So, they are considered artifacts that compare the production techniques and raw materials. This study aimed to examine the production techniques and provenience studies of Bihwa Gaya, which is estimated to be from the 5th to 6th centuries. According to the research, harness fittings were made of pure copper and were gilded with Au·Ag alloys on their surfaces. Hg was detected together and plated with a mercury amalgam method. As a result of the pendant (fish scales-pattern, oval and fish-tail shape), analysis showed that Fe in the background metal, Cu in the middle layer, and Au and Ag on the surface were the main components. The method of adhesion between Cu and Au·Ag gilded layers are plated by a mercury amalgamation method. So, it was identified by the gilt-iron·gold·bronze technique. Since the pendant (heart shaped) is found to be the main component of Fe in the background metal and Ag in the surface layer, the metal was made gilt-iron·silver technique. The background metal and gilding were additionally fixed using a rivet. The raw materials of 3 harnesses excavated from Changnyeong are plotted in zone 2 in the southern Korean Peninsula. And 16 harnesses were plotted in Chinese copper ore by Mabuchi Hishao in the Chinese Peninsula.

• The Journal of the Acoustical Society of Korea
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• v.42 no.3
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• pp.227-232
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• 2023

Underwater noise pollution has a significant impact on the marine environment. This study proposed a simple approach to estimate the acoustic radiation efficiency of structures with air bubble layers. The method considered the insertion loss caused by the air bubble layer through post-processing of numerical results, assuming that insertion loss is equivalent to attenuation as demonstrated by previous studies. The proposed approach was validated by comparing it with a fully coupled analysis for plate structure models. The commercial finite element program COMSOL Multiphysics was used for the acoustic-structure interaction analysis, and the acoustic characteristics of air bubble layer for the fully coupled analysis was simulated by on the Commander and Prosperetti theory. The trends indicated good agreement between the simple approach and the fully coupled analysis in terms of radiation efficiency. It is confirmed that the proposed method is providing insight into the principal mechanism of underwater noise reduction for the bubble layer on the wedge-shaped structure.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.179-179
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• 1999

Cu3AU(100) 단결정은 fcc 구조를 가지고 있으며 (100)면은 Cu와 Au가 1:1로 존재하고 가운데(200)면은 Cu만 존재한다. 따라서 Au 층은 (100)면에서만 존재하여 각 Au층은 서로 0.5nm 떨어져 있다. 이와 같은 Cu3Au(100) 단결정을 MEIS(Medium Energy Ion Scattering Spectroscopy) 실험 장비를 사용하여 0.35nm 떨어져 있는 Single unit cell의 윗면과 아래면, 즉 첫 층의 Au와 셋째층의 Au의 층분리를 통해서, 온도 변화에 따른 Cu3Au(100) 단결정의 표면 물리적 현상인 surface induced disorder을 밝혀내고자 한다. 우선 두 Au층의 분리 시도는 수소이온을 이용한 실험 조건에서는 extremely glancing exit angle 등 극한의 산란조거에서도 성공하지 못하였다. 깊이 분해능을 정해주는 electronic energy loss를 극대화하기 위해 수소이온이 아닌 질소 이온을 사용하여 energy spectra를 측정해 본 결과 아래 그림에서와 같이 표면 Au 층과 표면 셋째 Au층을 구분할 수 있었다. <110>으로 align된 조건에서는 셋째층의 Au 원자들이 완전히 shadow cone 내부에 존재하여 관측되지 않지만 9.75$^{\circ}$ tilt 한 경우 셋째층의 Au 원자들이 shadow cone 바깥으로 나오게 되어 그림에서와 같이 첫째 층과 셋째 층이 확실히 분리되어 측정되었다. 이를 바탕을 Cu3Au(100)의 온도변화에 다른 order disorder and segregation 현상을 측정하였다. ordered Cu3Au(100)은 28$0^{\circ}C$ 근처에서 surface층이 먼저 disordered상으로 바뀌는 surface induced disorder 현상이 일어나고 bulk transition 온도 39$0^{\circ}C$ 이하에서 R.T으로 온도를 낮추면 본래의 ordered 구조로 되돌아간다. 하지만 bulk transition 온도를 지나면 order-disorder transition이 비가역적이고 segregation 현상이 일어난다.

• Journal of the Speleological Society of Korea
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• no.79
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• pp.41-46
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• 2007

지구자기장의 성인에 대하여 고찰하고 기존 학설에 대한 신 모델을 제안하였다. 지자기 성인의 가장 유력한 이론적 모델은 열전류와 열화학적 전류에 의한 자기장 형성이다. 하지만, 이 모델은 매우 한정적 조건을 바탕으로 설명하고 있으며, 동시에 지자기의 분산과 세기의 상쇄 요인을 내포하고 있기 때문에 설득력이 저하된다. 그러나 본 제안의 가설에서 주장하는 이온층 전류에 의한 지자기의 성인은 그와 같은 분산 요인이 있을 수 없으며, 그 결과로 나타나는 지자기의 새기와 방향도 일정하게 형성됨이 해석 가능하기 때문에 타당성과 설득력이 높은 완벽한 이론이다. 따라서 이온층 전류에 의한 보다 안정적인 지자기성인의 전자기학적 신 모델을 제안한다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.331-334
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• 2009

본 논문에서는 계측을 통한 초고층 무량판 구조물의 횡강성 산정식의 유효성을 검정하였다. 초고층 건축물의 풍진동은 건축물의 사용성 평가에 중요한 구조설계요인 중 하나이다. 신뢰성 있는 풍하중 및 풍진동을 얻기위해서는 정확한 고유주기의 예측이 중요하며 고유주기 예측에 오차가 있을 경우 하중을 지나치게 과대평가하게 되는 문제를 유발하게 된다. 본 논문에서는 최근들어 국내에서 본격적으로 증가하고 있는 초고층 무량판 구조시스템의 건축물에 대한 해석 모델링과 실측을 통하여 추정된 무량판 초고층 건물의 동적특성을 바탕으로 구조해석과 동적거동의 계측을 통하여 내풍설계를 위한 횡강성 및 주기를 산정하는 연구를 수행하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2016.06a
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• pp.33-34
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• 2016

본 논문에서는 HVS(human visual system)의 특성을 고려한 새로운 스케일러블 코딩방법을 제안한다. 제안된 방법은 먼저 영상 내에서 관심영역(saliency map)을 찾고 관심영역을 제외한 부분에 에지 보존 필터를 적용한다. 그 영상은 정해진 양자 파라미터 값으로 인코딩 되어 제안된 코딩 시스템의 베이스 층(base layer)이 된다. 기존 스케일러블 코딩 표준에서의 베이스 층과 다르게 본 논문의 베이스 층은 관심 있는 중요영역(foreground)을 보존하고 또한 배경(background)의 에지 성분도 보존한다. 기본 층이 전송되면 개선층(enhancement layer)은 원 영상과 복원된 베이스 층 영상간의 차분 영상에서 관심영역 순으로 보내진다. 실험은 HEVC 를 바탕으로 수행되었고 스케일러블 코딩 표준인 SHVC 와 관심영역에서 비교를 했을 때 제안된 알고리즘이 더 높은 PSNR 을 가지는 것을 확인하였다. 또한 전체적으로 지각적인 품질(perceptual quality) 또한 향상되었음을 확인하였다.

• Korean Journal of Heritage: History & Science
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• v.47 no.1
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• pp.134-151
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• 2014

This paper deals with a review of the structure and production techniques of the Dried-lacquer Amitabha Buddha statue enshrined in Geungnakjeon Hall of Simhyangsa Temple, located in Daeho-dong, Naju-si, Jeollanam-do, Korea. To achieve this goal, X-ray date and two rounds of field research were performed. The data collected were reviewed, and a sample peeled off from the damaged part was analyzed to investigate the structure and material of the background layer. The results revealed that the Simhyangsa Temple Buddha statue was an almost empty Dried-lacquer(Hyeopjeo) Buddha statue where wood core had not been framed and inserted in the statue. It was thus observed that considering that the clothes wrinkles clearly remained, the same one as the irregularity of the outer clothes wrinkles, the Dried-lacquer layer was lifted made in an almost complete shape in the process of forming the clay figure as the origin form. The statue was found to be diagonally incised from the top of the head to the back of the neck to remove the clay and wood core. But in other sites, no incision was confirmed. It was observed that on the site of the head where the incision was made, an adhesives(lacquer or paste) was used. In addition, the black eyes were impacted with beads and the ears, hands, bands, and knots were made of wood. These features are identically shown in the Dried-lacquer Amitabha Buddha statue from Seonguksa Temple, known as a work of the late Goryeo dynasty; the Seated Dried-lacquer Buddha statue in Okura Museum of Art in Tokyo, Japan; the Seated Dried-lacquer Amitabha Buddha statue from Jungnimsa Temple, know as a work of the early Joseon dynasty; and the Seated Vairocana Buddha statue in Bulhoesa Temple, the Seated Dried-lacquer Amitabha Buddha and the Seated Dried-lacquer Buddha statue from Silsangsa Temple. The analysis of the back layer demonstrated that the ground layer and the red lacquer were the production of the time. In particular, the bone ash used for the ground layer was also coated for the ground layer of Buddha statues as well as for the production of the lacquerware during the Goryeo dynasty. It was also found that gold mending was conducted more than twice even in modern times and that the layer of the production time was well preserved despite gold mending several times.

• Economic and Environmental Geology
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• v.47 no.4
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• pp.455-466
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• 2014

We investigated reservoir properties of coalbed methane and typical development of drilling, completion, and stimulation methods. We optimized selection technique for development methods by consifering characteristics of coalbed methane resercoir in the San Juan, Black Warrior and Powder River basins of United States. Finally, well-optimized development methods for coalbed methane in the Barito Basin, Indonesia are suggested. This study may be useful to select economical and efficient drilling, completion, and stimulation methods in coalbed methane development especially in Indonesia.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.727-732
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• 2022

Applying the calculated cross-sectional reduction due to the corroded rebar investigated in the field to the numerical analysis model, the damage pattern and delamination of concrete in the field showed a tendency relatively similar to the numerical analysis results. It was analyzed that when the expansion pressure due to corrosion of the reinforcing bar is greater than the tensile stress of the concrete, cracks are generated and the concrete cover can be fracture. As a result of this study, the correlation between the corrosion rate of reinforcing bars and the crack occurrence of the concrete cover of the subway box structure was verified based on the numerical analysis and field test results. To prevent rebar corrosion, the corrosion rate can be reduced by applying rust prevention to the reinforcing bar and changing the material. In the case of exposed to a corrosive environment, the tensile strength of the concrete is improved by adjusting the concrete compressive strength to secure durability against the expansion pressure caused by the corroded rebar.