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Evaluating the Mechanical Properties of Fiber Yarns for Developing Synthetic Fiber Chains
Kyeongsoo Kim,Taewan Kim,Namhun Kim,Dokyoun Kim,Yongjun Kang,Seonjin Kim 한국해양공학회 2021 韓國海洋工學會誌 Vol.35 No.6
In this study, three types of synthetic fiber materials were evaluated, namely, DM20, SK78, and T147, to replace steel chains in shipbuilding and offshore fields with fiber chains as there is increasing demand for chains with lighter weights and improved usabilities. The strength and quasi-static stiffness were analyzed to select suitable yarns for the fiber chains. The durability of the yarn was evaluated by performing a 3-T (time to rupture) test as a specific tension level. The results of the experiment revealed excellent dynamic stiffness in DM20 and highest values of the windward and leeward stiffness in T147. 3-T linear design characteristic curves for a specific tension level were derived for the three types of fiber materials. The findings of this study can provide insights for improving strength and durability in fiber chain design.
Optimization of DME Reforming using Steam Plasma
Kyeongsoo Jung(정경수),U-Ri Chae(채우리),Ho Keun Chae(채호근),Myeong-Sug Chung(정명석),Joo-Yeoun Lee(이주연) 한국산업정보학회 2019 한국산업정보학회논문지 Vol.24 No.5
오늘날 세계 에너지 시장에서는 친환경 에너지의 중요성이 대두되고 있다. 수소 에너지는 미래의 청정에너지원이며 무공해 에너지원 중 하나이다. 특히 수소를 이용한 연료전지 방식은 재생에너지의 유연성을 높여주고 장기간 에너지 저장 및 변환이 가능해서 화석 자원의 사용에 따른 환경문제와 자원의 고갈로 인한 에너지 문제를 동시에 해결할 수 있는 방안으로 판단된다. 본 연구의 목적은 플라즈마를 이용하여 효율적으로 수소를 생산하는 방안으로, 온도에 따른 개질반응과 수율을 확인하여 DME(Di Methyl Ether)개질의 최적화 방안을 연구하는데 있다. 연구 방법은 2.45 GHz의 전자파 플라즈마 토치를 사용하여 청정 연료인 DME를 개질하여 수소를 생산하고. 저온 조건(T3 = 1100℃), 저온 과산소 조건(T3 = 1100℃), 고온 조건(T3 = 1376℃)에서 가스화 분석을 진행하였다. 저온 가스화 분석을 통해 1100℃ 근처에서는 불안정한 개질 반응으로 인해 메탄이 발생하는 현상을 확인하였고, 저온 과산소 가스화 분석은 저온 가스화 분석과 비교하였을 때 수소는 적으나 이산화탄소는 많은 것을 확인할 수 있었다. 고온에서의 가스화 분석을 통해 1200℃ 이상에서는 메탄이 발생하지 않았고 약1150℃ 부터 메탄이 발생하는 것을 알 수 있었다. 결론적으로 개질반응시 온도가 높을수록 수소의 비율이 높아지나 CO 비율은 증가하는 것을 볼 수 있었다. 그러나, 가스화기의 구조적인 문제로 인해 열손실과 개질의 문제가 발생함을 확인하였다. 향후 연구의 발전 방향으로는, 가스화기 개선을 통해 불완전한 연소를 줄여 높은 수율의 수소를 얻고 일산화탄소, 메탄과 같은 기체의 발생을 낮출 필요성이 있는 것으로 판단된다. 본 연구에서 제안하는 DME를 수증기 플라즈마 개질하여 수소를 생산하는 최적화 방안이, 향후 친환경, 신재생 에너지를 생산하는데 의미있는 기여를 할 수 있을 것으로 기대한다. In today"s global energy market, the importance of green energy is emerging. Hydrogen energy is the future clean energy source and one of the pollution-free energy sources. In particular, the fuel cell method using hydrogen enhances the flexibility of renewable energy and enables energy storage and conversion for a long time. Therefore, it is considered to be a solution that can solve environmental problems caused by the use of fossil resources and energy problems caused by exhaustion of resources simultaneously. The purpose of this study is to efficiently produce hydrogen using plasma, and to study the optimization of DME reforming by checking the reforming reaction and yield according to temperature. The research method uses a 2.45 GHz electromagnetic plasma torch to produce hydrogen by reforming DME(Di Methyl Ether), a clean fuel. Gasification analysis was performed under low temperature conditions (T3 = 1100°C), low temperature peroxygen conditions (T3 = 1100°C), and high temperature conditions (T3 = 1376°C). The low temperature gasification analysis showed that methane is generated due to unstable reforming reaction near 1100℃. The low temperature peroxygen gasification analysis showed less hydrogen but more carbon dioxide than the low temperature gasification analysis. Gasification analysis at high temperature indicated that methane was generated from about 1150°C, but it was not generated above 1200°C. In conclusion, the higher the temperature during the reforming reaction, the higher the proportion of hydrogen, but the higher the proportion of CO. However, it was confirmed that the problem of heat loss and reforming occurred due to the structural problem of the gasifier. In future developments, there is a need to reduce incomplete combustion by improving gasifiers to obtain high yields of hydrogen and to reduce the generation of gases such as carbon monoxide and methane. The optimization plan to produce hydrogen by steam plasma reforming of DME proposed in this study is expected to make a meaningful contribution to producing eco-friendly and renewable energy in the future.
Photometric Properties of the HW Vir-type Binary OGLE-GD-ECL-11388
Hong, Kyeongsoo,Lee, Jae Woo,Lee, Dong-Joo,Kim, Seung-Lee,Koo, Jae-Rim,Park, Jang-Ho,Lee, Chung-Uk,Kim, Dong-Jin,Cha, Sang-Mok,Lee, Yongseok Astronomical Society of the Pacific 2017 Publications of the Astronomical Society of the Pa Vol.129 No.971
<P>We present the first extensive photometric results for the eclipsing binary OGLE-GD-ECL-11388 with a period of about 3.5 hours located in the Galactic disk. For the photometric solutions, we obtained the BVI light curves from both the KMTNet observations in 2015 and the OGLE -III survey data from 2001-2009, which show striking reflection effects and very sharp eclipses. The light curve synthesis indicates that the eclipsing system is a HW Virtype binary with a mass ratio of q = 0.289, an orbital inclination of i = 81.9 deg, and a temperature ratio between both components of T-2/T-1 = 0.091. A frequency analysis was applied to the light residuals from our binary model; however, no pulsating periodicity from the subdwarf B -type primary component was detected under signal-tonoise amplitude ratios larger than 4 0 A total of 27 minimum epochs spanning 15 yr were used to analyze the eclipse timing variations of OGLE-GD-ECL-11388. It was found that the orbital period has varied due to a continuous period decrease at a rate of dP/dt = -1.1 x 10(-8) day yr(-1) or a sinusoidal oscillation with a semiamplitude of K = 35 s and a cycle of P-3 = 8.9 yr. The period decrease may be explained by an angular momentum loss via magnetic stellar wind braking or may be only a part of the sinusoidal variation. We think the most likely interpretation of the orbital period change, at present, is the light -time effect via the presence of a third body with a mass of M-3 sin i(3) = 12.5 M-Jup, putting it in the boundary zone between planets and brown dwarfs.</P>