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내염 고성능 뿜어불이기 콘크리트를 이용한 염해열화 콘크리트 구조물 단면보수 공법개발
최성웅 ( Choi Sung-yong ),박명호 ( Park Myoung-ho ),조영종 ( Jo Yeong-jong ) 한국구조물진단유지관리공학회 2020 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.24 No.2
동절기 제설제의 사용량은 계속적으로 증가되며, 이에 따른 콘크리트 구조물의 염해열화 증대 시설유지관리법 개정에 따른 3종 구조물관리 추가로 유지보수 물량증대 있다. 실제 유지보수 현장에서는 Hand-breaker파쇄후 보수 모르타르로 단면보수를 실시한 부분에서 재열화 문제발생로 새로운 단면보수공법의 필요성이 대두되고 있다.
최성웅(Sung O. Choi),전양수(Yang-Soo Jeon),박의섭(Eu-Sup Park),정용복(Yong-Bok Jung),천대성(Dae-Sung Chun) 한국암반공학회 2005 터널과지하공간 Vol.15 No.3
지하채굴적의 함몰, 지하수의 무분별한 양수, 연약지반의 압밀 및 얕은 심도에서의 지하굴착 등의 원인으로 기인하는 지반침하는 국가 기간망에 심각한 안전문제를 야기하고 있다. 특히 인구밀집 지역에서는 가옥 및 기타 시설물의 붕괴요인으로 작용함에 따라 국민의 생활권을 위협하고 있는 실정이다. 따라서 본 연구에서는 지반침하가 발생한 이후 조사와 보강작업이 실시되는 기존의 수동적인 접근법을 달피하고 지반침하를 예측하여 피해발생을 최소화하기 위해 사례분석을 통해 국내 지질조건에 부합하는 지반침하의 메커니즘을 규명하였으며, 지반침하에 영향을 미치는 제반 요인들을 수치해석적으로 분석하였다. 또한 이를 통해 각 요인들의 가중치를 점검, 합리적인 판단 기준을 제시코자 하였으며, 지반침하 발생여부를 파악할 수 있는 프로그램을 제작하여 이러한 가중치를 접목시킴으로써 지반침하 발생가능성에 대한 객관적인 판단과 정량적인 기준을 제시할 수 있도록 하였다. 이러한 연구결과를 통해, 지질학적 분포 현황과 같은 자연적인 조건과 지하채굴적 및 양수 현황 등과 같은 인공적인 조건들을 결부시켜 추후 전 국토에 대한 지반침하 재해 위험지도를 작성함으로써 지반침하발생 가능성을 억제하고 그 피해규모를 최소화할 수 있는 근간을 마련하였다. Surface subsidence which occurs with several reasons, such as collapse of gangway, discharge of groundwater, compaction of weak rock mass, and tunnel excavation in shallow depth, gives rise to a serious problem in national infra-structures. In this study, therefore, the mechanism of subsidence has been examined numerically to overcome the passive approach on subsidence occurrence area. With many kinds of numerical studies, the major geotechnical parameters have been selected and the weighted values have been defined for each parameters. Also the authors developed the numerical program which can estimate the possibility of subsidence occurrence, and proposed the decision method for objective and quantitative guideline. It is anticipated that this research will be helpful to establish the hazard map on subsidence region.
Alloy718 마찰용접재의 비커스 경도의 통계적 성질에 관한 연구
권혁용(HYEOK-YONG KWON),최성웅(SUNG-YOONG CHOI),이상열(SANG-YEAL LEE),공유식(YU-SIK KONG),김선진(SEON-JIN KIM) 한국해양공학회 2008 韓國海洋工學會誌 Vol.22 No.5
The objective of this paper is the investigation of the statistical properties of Vickers hardness (HV) of friction welded parts in nickel based super resisting steel, alloy 718 steel. First, we examine the statistical properties on the case of as-welded parts. Several Virkers indentations were made under same nominal conditions. This was repeated for three different applied loads, 100, 200 and 300g with a duration time, 10 second. The arithmetic mean of Vickers hardness in base metal (BM) materials is larger than that of HAZ in all applied loads. The measure of dispersion, that is, the coefficient of variation (COV) for BM and HAZ is decreased by increasing with the applied load. The distribution of Vickers hardness was not found to be symmetric type. The probability distribution of Vickers hardness was well followed Weibull distribution. The shape parameter and the scale parameter (characteristic hardness) are increased by increasing with the applied load, as both BM and HAZ.
그래핀 옥사이드(Graphen Oxide, GO)와 환원 그래핀의 (Reduced graphe oxide, R-GO)의 물리화학적 특성 연구
김무선,이호용,최성웅,Moo-Sun Kim,Ho-Yong Lee,Sung-Woong Choi 한국복합재료학회 2023 Composites research Vol.36 No.3
The manufacturing technology of composite material is applicable with filler characteristics maintaining low cost, flexibility, and easy process to develope the various functional composite materials. To realize functional composites, various researches on the high performance of composite materials using graphene as a filler is being actively conducted. In this study, physical and chemical properties were investigated using graphene to improve high functional properties. Graphene oxide (GO) was prepared using graphane nanoplatelet (GNP), and reduced graphene oxide (R-GO) was formed by reducing GO. The physical properties of GO and R-GO were analyzed, and the reliability of the manufactured method was reviewed by comparing that of GNP results. As a result of analysis by Raman spectroscopy, in the case of R-GO, it was confirmed that the intensity of D-peak and G-peak decreased compared to GO, and an increase of 0.08 was observed through the ratio of ID/IG. For the FTIR results, GO and RGO has a repeating C-C and C=C connection structure unlike GNP. GO and R-GO show clear peaks for C-O bond, C=C bond, C=O bond, and O-H bonding. As a result of X-ray diffraction analysis, GNP showed a wide diffraction peak at 25.86° of (002) plane characteristics, whereas GO and R-GO showed peaks corresponding to (001) and (100) planes. It was also found that the interlayer distance of GO increased by about 2.6 times compared to GNP.
Vacuum Filtration method를 이용한 단섬유(short fiber) 배열 영향성 분석
이성권,김무선,이호용,최성웅,Sung-Kwon Lee,Moo-Sun Kim,Ho-Yong Lee,Sung-Woong Choi 한국복합재료학회 2023 Composites research Vol.36 No.3
Although composite materials are increasingly utilized in general high-strength structures, the demand of performance characteristics as the multifunctional materials has been increased especially in the area of complex electronic devices. While the heat dissipation properties of devices are typically required properties, control of thermal property of composite material especially in the vertical direction is one of the problems to be solved due to its lamination process. In this study, CFRP was manufactured using the Vacuum filtration method for three types of solvent and CFs. In the composite material manufacturing process, the effect of solvent was examined using three solvents where solvents are most frequently used for the dispersion of fibers. Morphology of fiber was observed through a microscope to confirm the arrangement of CFs in the vertical direction. The alignment of fiber was examined through the measurement of the thermal conductivity of the manufactured specimen. For the thermal conductivity measurement, the higher thermal conductivity was obtained with the lower aspect ratio of CF. For the thermal conductivity in the through-plane direction, 8.687 W/m·K, 10.322 W/m·K, and 13.005 W/m·K of thermal conductivity was measured in the DMF, NMP and Acetone, respectively.