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- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
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- 저자 : 최환석(Hwan-Seok Choi) (검색결과 295 건)
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최환석(Hwan-Seok Choi),한영민(Young-Min Han),김영목(Young-Mog Kim) 한국추진공학회 2009 한국추진공학회 학술대회논문집 Vol.2009 No.11
우주발사체 개발을 위한 75톤급 액체로켓엔진 개발에 앞서 선행개발을 통해 습득한 30톤급 액체로켓 엔진 기술을 토대로 75톤급 액체로켓엔진 연소기 기술 검증에 착수하였다. 이를 위하여 국내 연소시험 설비 여건을 고려한 기술검증 계획을 수립하고 기술검증시제를 제작하여 제한된 조건에서 성능평가시험을 수행하였다. 본 논문은 75톤급 액체로켓 연소기 기술검증을 위한 계획과 현황에 대하여 소개한다. Technology demonstration for the development of a 75-tonf liquid rocket engine(LRE) thrust chamber for a space launch vehicle has been started on the basis of the previously acquired 30-tonf LRE technologies. For this purpose, a technology demonstration plan was established upon considering the currently available firing test facility in Korea and performance evaluation firing tests were performed on technology demonstration model thrust chambers under a restricted test condition. This paper describes the plan and current status of technology demonstration for a 75-tonf LRE thrust chamber.
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최환석(Hwan-Seok Choi),김귀철(Gwui-Cheol Kim),신현재(Hyun-Jae Shin) 한국생물공학회 2012 KSBB Journal Vol.27 No.2
To develop potential cosmetic ingredients with antimicrobial and antioxidant activities of 4 Korean bamboo species (P. bambusoides, P. nigra var. henonis, P. pubescens and Sasa coreana) using three different extraction methodswater, ethanol and supercritical fluid extraction. Antimicrobial activities and DPPH assay have been examined. Among the antimicrobial activities against two test strains, Escherichia coli and Staphylococcus aureus, ethanol extracts of 3 bamboo trees, P. bambusoides, P. nigra var. henonis, and P. pubescens, showed stronger than those of supercritical extracts. However, 4 bamboo supercritical extracts showed dose-dependent increase in antioxidant activity by DPPH assay. These results suggest that water fraction of bamboo extracts may be useful for the cosmetic ingredient with low cytotoxicity.
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아크릴산 단량체와 아지리딘 경화제 함량에 따른 점착제의 점착물성 변화
최환석(Hwan Seok Choi),황효연(Hyo Yeon Hwang),정선경(Sun Kyoung Jeoung),이승구(Seung Goo Lee),이기윤(Kee Yoon Lee) 한국고분자학회 2012 폴리머 Vol.36 No.1
Solution type pressure sensitive acrylic adhesives were synthesized from 2-ethylhexyl acrylate (2-EHA) as a base monomer and acrylic acid as a functional monomer. The surface energy and basic physical properties of synthesized PSA (pressure sensitive adhesives) were investigated as a function of contents of acrylic acid and crosslinking agent. The structures of adhesive were identified by FTIR. Viscosities and molecular weights of PSA were measured by a Brookfield viscometer and GPC, respectively. Consequently, molecular weight and viscosity increased as the contents of acrylic acid increased up to 6 wt% and then decreased at higher contents. Surface energy increased as the contents of acrylic acid increased owing to the increase of COOH groups, which yielded the enhancement of polarity of PSA. On the other hands, their peel strengths were inversely proportional to molecular weight and showed tendencies of decreasing as the contents of acrylic acid and crosslinking agent increased.
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추력 30톤급 액체산소/케로신 로켓엔진 연소장치 개발(II)-가스발생기
최환석(Hwan-Seok Choi),서성현(Seonghyeon Seo),김영목(Young-Mog Kim),조광래(Gwang-Rae Cho) 한국항공우주학회 2009 한국항공우주학회지 Vol.37 No.10
추력 30톤급 펌프공급방식 액체로켓엔진을 위한 가스발생기 개발 과정에 관하여 기술하였다. 액체산소와 케로신을 추진제로 연료 과농 조건에서 작동하는 가스발생기의 개발을 위해 분사기 개발에서부터 시작하여 축소형, 실물형 개발시제를 거쳐 가스발생기 단품개발을 성공적으로 완료하였다. 가스발생기 설계 과정에서 다양한 해석적 방법을 적용하였으며 점화 시험, 연소성능 및 연소안정성 평가시험, 내구성 평가시험 등을 통해 가스발생기의 성능요구사항을 시험적으로 검증하였다. 개발된 가스발생기는 연소압 및 혼합비운용 영역 내에서 안정적으로 작동하며 성능 및 수명 요구조건을 만족시킴을 확인하였다. The development process of a gas generator for a 30-tonf pump-fed space liquid rocket engine is described. Starting from the development of an injector, followed by subscale and full-scale test specimens, the development of LOx/kerosene fuel-rich gas generator has been concluded successfully. Various analytical methods have been utilized in the course of design and the performance requirements have been verified experimentally through ignition tests, combustion performance and stability assessment tests and duration tests. The gas generator has proven its workability and stability within a defined operation window of varying chamber pressure and mixture ratio and demonstrated compliance to the performance and life time requirements.
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