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유도초음파의 비선형 파라미터를 이용한 항공기 구조체의 복합재료 적층판 열화 평가
조윤호(Younho Cho),김도연(Doyoun Kim),최흥섭(Heungsoap Choi),이준현(Joonhyun Lee) 한국비파괴검사학회 2010 한국비파괴검사학회지 Vol.30 No.2
본 연구에서는 유도초음파를 이용하여 다양한 온도에서 사용되어지는 항공기 복합재료의 건전성에 대하여 평가하였다. 항공기가 지상과 비행고도에서 운행할 때의 온도편차나, 반복되어지는 열주기 횟수와 같이, 항공기가 운행되어지는 온도와 관련하여 복합재료의 건전성에 결정적인 영향을 미치는 요소에 관한 연구는 항공기 안전에 있어서 매우 중요한 요소가 되고 있다. 본 연구에서는 유도초음파를 이용하여 항공기의 운행환경과 유사한 환경 하에서 열피로가 가해진 항공기의 복합재료 시편을 평가하였다. 유도초음파의 분산선도 곡선은 서로 다른 열피로가 가해진 시편에 대한 민감성을 나타내기 위해 최적의 모드를 선택하는데 사용되었다. 현재 제시된 접근법 또한 항공기의 건전성을 평가하는데 있어서 하나의 도구로 구현될 수 있다. The purpose of this study is to assess the condition of composites used in aircraft under varying temperature environment with ultrasound guided wave technique. Investigation of crucial influential factor on the composite health monitoring related to aircraft operational environments such as the number of thermal cycles and temperature deviation between ground level and flight altitude has been of a great concern for aircraft safety issue. In this study, ultrasonic guided wave health monitoring scheme is proposed to evaluate composite specimens damaged with the thermal fatigue simulating aircraft operational condition. Guided wave dispersion curves are used to select right modes which show a promising sensitivity to each different thermal fatigue damage level. The present approach can be also implemented as one of on-lines health monitoring tools for aircraft.
Experiments of dimethyl ether autothermal reforming optimization
최승현(Choi, Seunghyeon),배중면(Bae, Joongmyeon),김태훈(Kim, Taehun),장덕진(Jang, Duckjin),김도연(Kim, Doyoun) 한국신재생에너지학회 2011 한국신재생에너지학회 학술대회논문집 Vol.2011 No.11
Dimethyl ether (DME) is an attractive fuel as a hydrogen carrier for mobile PEMFC applications. However, its reforming technologies are rarely studied especially by using autothermal reforming (ATR) method. This work explored the impact of operating conditions to the performance of DME ATR. Temperature, Steam to carbon ratio(SCR), Oxygen to carbon ratio(OCR) and Gas hourly space velocity(GHSV) were considered as the operating conditions. As results, conversion efficiency was increased as the temperature increased, but saturated around 700?C. There was no significant effect of SCR on conversion efficiency, but high SCR led reactions in endothermic manner. High OCR substantially suppressed conversion efficiency, but it helped to sustain the temperature by stimulating exothermic reactions. Conversion efficiency was decreased as GHSV increased. The optimized operating conditions was suggested: 700?C, SCR of 1.5, OCR of 0.45 and GHSV below 15000/h and conversion efficiency was ~85% at the conditions.
직류전류 인가를 통한 김으로부터 포피라334의 대량 정제 고도화
장성주(Sung Joo Jang),이정훈(Jeong Hun Lee),서효현(Hyo Hyun Seo),이삭(Sak Lee),김지연(Jiyeon Kim),김도연(Doyoun Kim),모상현(Sang Hyun Moh) 한국해양바이오학회 2020 한국해양바이오학회지 Vol.12 No.1
Marine algae contain a variety of substances, such as mycosporine-like amino acids, which can defend against UV irradiation. Among them, Porphyra-334 derived from Porphyra yezoensis is attracting attention as a novel active ingredient for anti-aging cosmetics because of its excellent anti-oxidative, anti-inflammatory, and wound-healing properties through promoting skin cell migration. In this study, a process using direct current (DC) for increasing the yield of large-scale purification of Porphyra-334 was developed. When DC was applied to obtain Porphyra-334 efficiently, the purification time was shortened by approximately 1/4 compared with the process wherein DC was not applied; moreover, the yield of purification was improved.