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Inter-lamina Shear Strength of MWNT-reinforced Thin-Ply CFRP under LEO Space Environment
문진범,김천곤 한국복합재료학회 2017 Composites research Vol.30 No.1
In this paper, the inter-lamina shear strength (ILSS) of multi-wall carbon nanotube (MWNT) reinforced carbon fiber reinforced plastics (CFRP) and thin-ply composites were verified under low earth orbit (LEO) space environment. CFRP, MWNT reinforced CFRP, thin-ply CFRP and MWNT reinforced thin-ply CFRP were tested after aging by using accelerated ground simulation equipment. The used ground simulation equipment can simulate high vacuum (2.5 × 10-6 torr), atomic oxygen (AO, 9.15 × 1014 atoms/cm2·s), ultraviolet light (UV, 200 nm wave length) and thermal cycling (-70~100°C) simultaneously. The duration of aging experiment was twenty hours, which is an equivalent duration to that of STS-4 space shuttle condition. After the aging experiment, ILSS were measured at room temperature (27°C), high temperature (100°C) and low temperature (-100°C) to verify the effect of operation temperature. The MWNT and thin-ply shows good improvement of ILSS at ground condition especially with the thinply. And after LEO exposure large degradation of ILSS was observed at MWNT added composite due to the thermal cycle. And the degradation rate was much higher under the high temperature condition. But, at the low temperature condition, the ILSS was largely recovered due to the matrix toughening effect.
비구속 삽입된 직물 섬유를 이용한 샌드위치 쉴드의 초고속 충격 해석
문진범 ( Jin Bum Monn ),박유림 ( Yu Rim Park ),손길상 ( Gil Sang Son ),김천곤 ( Chun Gon Kim ) 한국복합재료학회 2011 Composites research Vol.24 No.3
본 연구에서는 우주 파편들과의 초고속 충돌로부터 우주 구조물을 보호하기 위한 새로운 하이브리드 복합재료 쉴드가 제안되었다. 제안된 쉴드의 유한요소 모델을 구성하고, 에너지 흡수율을 예측하기 위해서 유한 요소 해석을 수행하였다. 최종모델의 해석에 앞서 각 구성 요소인 알루미늄 판, PMMA 판 그리고 중간층인 직물 섬유의 해석이 먼저 수행되었으며, 각 요소의 유한요소 모델의 타당성이 검증되었다. 해석에 사용된 재료 물성은 고 변형률 속도에서의 재료 물성들을 예측하여 사용 하였으며, 해석 결과 개별 요소의 에너지 흡수율이 직물섬유를 제외하고는 잘 맞음을 확인하였다. 이후 하이브리드 복합재료 쉴드의 유한 요소 모델을 구성하였고, 직물섬유의 구속 조건을 고정과 비 구속의 두 가지로 나누어 해석을 수행하여 비교하였다. 이를 통해서 비구속 삽입된 섬유를 이용한 하이브리드 쉴드가 섬유 풀아웃 현상이 잘 구현되었고, 이로 인해 에너지 흡수율이 향상 될 수 있음을 최종 확인하였다. In this paper, a novel hybrid composite shield to protect space structures from hypervelocity impact of micrometeoroid and space debris is proposed. The finite element model of the proposed shield was constructed and finite element analysis was conducted to approximate the energy absorption rate. Before the final model analysis, analysis of each component including the aluminum plate, PMMA plate, and intermediate layer of fabric was performed, verifying the finite element model of each component. The material properties used in the analyses were predicted material property values for high strain rates. The analysis results showed that, other than the fabric, the energy absorption rate of each component was in agreement. Afterwards, the finite element model of the hybrid composite shield was constructed, where it was analyzed for the restrained and unrestrained fabric boundary condition cases. Through the finite element analysis, the fiber pullout mechanism was realized for the hybrid shield with free boundary inserted fabric, and it was observed that this mechanism led to energy absorption increase.
전과정평가기법에 의한 도로건설공사 환경부하량 평가 연구
문진석,주기범,서명배,강인석,Moon, Jinseok,Ju, Kibeom,Seo, MyoungBae,Kang, Leenseok 한국건설관리학회 2014 한국건설관리학회 논문집 Vol.15 No.6
최근의 국제사회는 경제성장에 따른 기상이변을 방지하고자 이산화탄소, 온실가스 등의 환경 오염물질 배출 저감을 요구하고 있다. 이러한 요구사항에 따라 에너지 다소비 산업 가운데 도로건설에 대한 효율적인 환경오염물질 배출 저감 방안이 요구된다. 본 논문에서는 전과정 영향평가의 절차에 적합한 도로건설공사 환경영향평가 프로세스를 제시하고, 이를 바탕으로 다수의 도로건설공사에 대하여 주요 건설자재의 환경부하량을 분석한 후, 1km 도로건설공사에서 발생하는 평균 환경부하량을 제시하고 있다. 주요자재수량에 대해서는 환경부하량에 대한 민감도 분석을 실시하였으며, 이러한 분석결과는 도로건설공사의 공법 및 자재별 수량 변화에 따른 전과정 환경영향평가에 유용하게 활용될 수 있을 것으로 판단된다. The global community demands the reduction of environmental pollution such as greenhouse gas and carbon dioxide emissions. According to these requirements, the road construction project in the highest energy consuming industry is required the efficient way of reducing environmental pollution emissions. In this study, during the whole life cycle process, an environment impact assessment was performed for the several road construction projects in order to evaluate environmental stress through the road construction process. This study provides a proper process of environment impact assessment for life cycle assessment (LCA) analysis of road construction project, and figures the environmental stress regarding to the major construction materials for the case projects. In addition, this study conducted a sensitivity analysis for the key materials of environmental stress through the quantity analysis of major materials for the 1km section of a road construction. By this sensitivity analysis of total environmental stress change from the different volumes of constructing materials, it would be useful information for the environment impact assessment for the future road construction project.