• 보존과학회지
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• 제34권2호
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• pp.129-135
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• 2018

Scientific investigation of cultural heritage can provide important information to understand the context of the object. To know the characteristics of the material is also an essential part of objects management and conservation. However, the identification and characterization of organic dyes used in archaeological and historical textiles are often limited by the restrictions in sampling. To cope with the difficulties, applications of high-performance techniques of surface analysis, such as Time of Flight-Secondary Ion Mass Spectra (TOF-SIMS) could be considered as a non or micro-destructive option. This study aims to examine the applicability of TOF-SIMS analysis to the detection of organic dyes from historical textiles. A group of silk fabrics dyed with vegetable dyes were artificially photo-aged to different degrees and analyzed with TOF-SIMS. Molecular and fragment ions from indigo were successfully detected from the aged samples; however, only some fragment ions were observed from gardenia and safflower dyed fabrics. Further studies with actual historical samples with extended examination scope would be necessary to assess the validity of this technique.

• Journal of Mechanical Science and Technology
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• 제18권7호
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• pp.1222-1235
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• 2004

This study examines the influence of geometry on the internal flow and macroscopic behavior of the spray in Diesel nozzles. For this investigation, two bi-orifice nozzles were employed: one cylindrical and one conical. The first step is to use a non-destructive characterization method which is based on the production of silicone moulds so that the precise internal geometry of the two nozzles can be measured. At this stage the nozzles have been characterized dimensionally and therefore the internal flow can be studied using CFD calculations. The results gained from this experiment make it possible also to ascertain the critical cavitation conditions. Once the critical cavitation conditions have been identified, the macroscopic parameters of the spray can be studied in both cavitating and non-cavitating conditions using a test rig pressurized with nitrogen and with the help of a image acquisition system and image processing software. Consequently, research can be carried out to determine the influence that cavitation has on macroscopic spray behavior. From the point of view of the spray macroscopic behavior, the main conclusion of the paper is that cavitation leads to an increment of the spray cone angle. On the other hand, from the point of view of the internal flow, the hole outlet velocity increases when cavitation appears. This phenomenon can be explained by the reduction in the cross section of the liquid phase in the outlet section of the hole.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1132-1132
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• 2001

This work is a further development of the method created by G. Krivoshiev in 1996 for elimination of peel interference and prediction of fruit flesh optical density. In this investigation, as it was earlier, the objects are observed as being structured by three successive layer “AlongrightarrowOlongrightarrowB” denoting “peel-flesh-peel”. In the first version of the method the transmittances of the surface layers A and B were measured according to Kubelka-Munk theory by means of their diffuse reflectance. At that the overall transmittance T was approximated in the form of a multiplication approximation being valid for plane-parallel layers of a non-scattering material. In this work this approximation was done away with applying the theory of discontinuum, respectively Benfor's equations. As a result two mathematical models were created for non-destructive prediction of fruit flesh optical density. These models are different from the ones based solely on Kubelka-Munk theory, the destruction being marked by the terms 1n (1 - $R_{A}R_{0}$) and 1n (1 - $R_{A}R_{B}$), where: $R_{A}$ and $R_{B}$ are reflectance values for the surface layers A and B; $R_{0}$ is the average reflectance of the internal layer that could be obtained empirically by means of a preliminary measurement of sufficiently large number of physically peeled fruits of a given species and variety.

• 자원환경지질
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• 제39권4호
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• pp.427-440
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• 2006

다른 물리탐사법과는 달리, 전자탐사의 실질적인 국내 활용과 연구는 1980년대부터이다. 이렇게 늦게나마 시작하게 된 것은 1970년대 미국 유학한 네 명의 연구자들의 영향이고, 이 들과의 공동연구와 유대는 현재까지 지속되고 있다. 그 동안 국내 연구진이 이룬 성과는 괄목할 만 하다. 이제 우리는 MT와 CSAMT탐사, 지자기수직탐사, 소형루프탐사, VLF탐사, GPR탐사, 시간영역 전자탐사 등 전 분야에 걸쳐 국제 수준의 기술력을 확보하게 되었고 신기술인 고주파수 전자탐사, 시간영역 전자탐사, 역산기법 분야에서 창의 있는 연구 성과를 내고 있다. 활용 분야도 지하자원탐사에서 지반조사, 환경조사, 고고학조사, 구조물 결함조사, 땅굴조사 등으로 엄청나게 확장되었다. 아직도 자료해석이 난삽하기 이를 데 없는 전자탐사법을 한 단계 높일 결정적인 돌파구가 국내 연구진에 의해서 나올 날이 멀지 않을 것이다.

• 지구물리와물리탐사
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• 제16권2호
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• pp.79-90
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• 2013

지반조사에서 비파괴 조사 기술은 시추조사보다 경제적으로 비용이 덜 들고 광역에 걸친 지반정보를 제공하는 장점이 있다. 하지만 지반설계정수로서 적용하기에는 어려운 한정된 정보만을 제공하게 된다. 이를 극복하기 위해, 비파괴 조사 방법 중 하나인 전기비저항 탐사를 모형토조실험에 적용하여, 토질상태에 따른 비저항 반응과 함수비에 따른 비저항 반응을 분석하여 비저항 거동 양상에 대한 연구를 수행하였다. 실험에 사용한 토질은 주문진 표준사, 마사토이며 각 토질의 입도 분포, 균등계수를 구하여 실험에 있어 실험재료의 균질한 상태를 유지하였다. 실험에 사용한 모형의 제원은 $160{\times}100{\times}50$ (cm)의 아크릴 재질 토조이며, 각 토질의 높이는 30 cm를 유지하였다. 5TE(함수비측정센서)센서를 7 ~ 8cm 간격으로 수직하게 꽂아 층별 함수비를 측정하였다. 모형실험 결과 주문진 표준사는 비저항 거동 양상이 함수비에 민감하게 반응하는 것을 알 수 있었으며, 마사토는 함수비에 따라 비저항이 낮아진 후에도 시간경과에 따른 거동 양상에 큰 변화가 없는 것을 관찰하였다. 또한 토조 실험에 사용된 토양과 유사한 테스트 베드를 선정하여 그 반응을 비교 분석하였다. 이러한 실험을 통해 토질 상태와 함수비에 따른 다양한 비저항 거동 양상 자료를 수집하고, 비파괴 조사기술의 정확도를 향상 시켜 나간다면 지반설계정수를 산정하는데 있어 기초적인 연구가 될 수 있음을 확인하였다.

• Earthquakes and Structures
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• 제10권3호
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• pp.523-538
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• 2016

Besides their spiritual significance, minarets are humanity's cultural heritage to the future generations due to their historical and architectural attraction. Currently, many historical masonry minarets are damaged and destroyed due to several reasons such as earthquakes and wind. Therefore, safety of these religiously significant buildings needs to be thoroughly investigated. The utmost care must be taken into account while investigating these structures. Our study investigated earthquake behavior of historical masonry minaret of Haci Mahmut Mosque. Destructive and non-destructive tests were carried out to determine earthquake safety of this structure. Brick-stone masonry material properties of structure were determined by accomplishing ultrasonic wave velocity, Schmidt Hammer, uniaxial compression (UAC) and indirect tension (Brazilian) tests. Determined material properties were used in the finite element analysis of the structure. To validate the numerical analysis, Operational Modal Analysis was applied to the structure and dynamic characteristics of the structure were determined. To this end, accelerometers were placed on the structure and vibrations due to environmental effects were followed. Finite element model of the minaret was updated using dynamic characteristics of the structure and the realistic numerical model of the structure was obtained. This numerical model was solved by using earthquake records of Turkey with time history analysis (THA) and the realistic earthquake behavior of the structure was introduced.

• 보존과학회지
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• 제38권4호
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• pp.314-326
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• 2022

Investigation of conservation status, optical survey, infrared thermography, and ultrasonic examination were performed on Avalokitesvara Bodhisattva mural and Buddhist Monk Bodhidharma mural to determine the conservation status and physical properties. As a result of investigation of conservation status, the types of damage are largely divided into the wall and finishing layer damage, painting layer degradation, damage due to restoration materials, stains and contamination, and biological damage. As a result of the optical survey, drawing, stains, and repainted site were confirmed. Result of the infrared thermography, the delamination of the finishing layer was confirmed, and some locations and shapes of the wooden lath inside the wall were identified. The result of the 3D scanning, the deviation, and the separation of the wall was confirmed. As a result of ultrasonic examination, it was confirmed that the physical properties of the mural were identified and the ultrasonic speed was relatively low due to physical damage such as delamination and exfoliation of the finishing layer and cracking. Ultrasonic speed values were also high in some wall cracks or delamination, and it was confirmed by the infrared thermography results that the wooden lath inside the wall was located in those parts. It was possible to understand that the wooden lath inside the walls affects the ultrasonic speed during the ultrasonic examination. Therefore, management through periodic inspection of the relevant elements is necessary, and a countermeasure for damage that may occur in the future should be prepared along with intensive monitoring of the major damage identified in this diagnosis result.

• 한국구조물진단유지관리공학회 논문집
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• 제16권2호
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• pp.40-48
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• 2012

콘크리트내의 철근의 부식은 열화와 콘크리트 구조물의 조기파괴의 주된 원인이 된다. 본 연구에서는 비파괴 기법 중 전자기적 열유도방법과 적외선 열화상기법을 이용한 철근부식평가가 시도되었는데, 부식 또는 비부식된 철근의 열특성 차이를 이용한 것이다. 본 논문은 이러한 개념을 배경으로 수행한 실험적 연구이며, 유도전류를 통해 콘크리트 표면으로부터 내부 철근을 가열하고 외부의 적외선 카메라를 이용하여 표면의 온도변화를 관측한다. 피복두께가 다른 콘크리트 시편은 앞면과 배면의 피복두께를 동일하게 제조하여 앞면에서 가열과 배면에서의 온도측정을 동시에 할 수 있도록 고안되었다. IC (Impressed Current) 방법을 통하여, 철근 부식을 촉진하였으며, 적외선 화상을 통하여 온도가열과 냉각을 전 시험과정에 걸쳐 측정하였다. 본 실험을 통하여 부식/비부식 철근의 뚜렷한 온도변화를 확인하였으며, 부식된 시편에서 빠른 온도증가속도 및 냉각속도를 평가하였다. 본 연구는 콘크리트 매립철근의 비파괴적인 부식탐지의 가능성을 보여주고 있다.

• 비파괴검사학회지
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• 제34권5호
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• pp.349-355
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• 2014

다양한 산업분야에서 사용되는 압력용기는 발전설비의 70~80%를 구성하는 설비구조물로써 유속에 의한 감육결함 현상이 발생할 수 있으며 내부결함 측정이 설비의 안전진단 평가에 중요한 요소가 된다. 본 논문에서는 광계측 응용 비파괴검사 기술인 전단간섭법을 이용하여 압력용기의 비접촉 비파괴평가를 통한 발전설비의 안정성 확보와 신뢰성 향상에 있다. 이를 검증하기 위하여 압력용기에 임의의 결함을 가공하여 배관 순환 시스템을 적용한 내부의 온도 변화와 압력 변화에 따른 내부결함 계측 및 면외 변형량 계측에 대하여 실험과 해석을 수행하였다. 본 연구를 통한 결함의 존재 유무를 구분할 수 있도록 하는 가장 중요한 요소는 결함 두께, 폭 및 결함길이라 할 수 있으며 결함 두께, 폭, 길이가 커질수록 변형랑도 커짐을 확인할 수 있었다. 따라서 전단간섭법을 이용한 압력용기의 내부결함을 사전에 측정하여 배관의 신뢰성과 건전성을 확보하는데 주요할 것으로 보인다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.182-187
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• 2010

In the various fields of Civil Engineering, shear modulus is very important input parameters to design many constructions and to analyze ground behaviors. In general, a shear wave velocity profile is decided by various experiments before constructing a structure and, analysis and design are carried out by using decided shear wave velocity profile of the site. However, if civil structures are started to construct, the shear wave velocity will be increased more than before constructions because of confining pressure increase by the load of structure. The evaluation of the change in shear wave velocity profile is used very importantly when maintaining, managing, reinforcing and regenerating existing structures. In this study, a non-destructively geotechnical investigation method by using the HWAW method is applied to an evaluation of change in properties of the site according to construction. Generally, the space for experiments is narrow when underground of existing or on-going structures is evaluate, so a prompt non-destructive experiment is required. This prompt non-destructive experiment would be performed by various in-situ seismic methods. However, most of in-situ seismic methods need more space for experiments, so it is difficult to be applied. The HWAW method using the Harmonic wavelet transforms, which is based on time-frequency analysis, determines shear wave velocity profile. It consists of a source as well as short receiver spacing that is 1~3m, and is able to determine a shear wave velocity profile from surface to deep depth by one test on a space. As the HWAW method uses only the signal portion of the maximum local signal/noise ratio to determine a profile, it provides reliability shear modulus profile such as under construction or noisy situation by minimizing effects of noise from diverse vibration on a construction site or urban area. To estimate the applicability of the proposed method, field tests were performed in the change of geotechnical properties according to constructing a minimized modeling bent. Through this study, the change of geotechnical properties of the site was effectively evaluated according to construction of a structure.