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정태환(TAE-HWAN JOUNG),노인식(IN-SIK NHO),이재환(JAE-HWAN LEE),한승호(SEUNG-HO HAN) 한국해양공학회 2005 韓國海洋工學會誌 Vol.19 No.2
In order to consider the statistical properties of probability variables which are used in structural analysis, the conventional approach of using safety factors based on past experience, are usually used to estimate the safety of a structure. The real structures could only be analyzed with the error in estimation of loads, materials and dimensional characteristics. Errors should be considered systematically in the structural analysis. In this paper, we estimated the probability of failure of two pressure vessels, simultaneously, using computational analysis. One pressure vessel, theoretically, had no stiffener whereas the other had. This paper also discusses sensitivity values of random variables in the rounded parts of the pressure vessel which had ring-style stiffener in the center of the external area which had ring-style stiffener. Finally, we show that the reliability index, and the probability of failure, can be calculated to particular tolerance limits.
세가지 다른 모형의 덕트 프로펠러의 CFD 해석과 시험에 관한 연구
정태환(Tae-Hwan Joung),정성재(Seong-Jae Jeong),이승건(Seung-Keon Lee) 한국해양공학회 2014 韓國海洋工學會誌 Vol.28 No.3
In this study, propeller open water characteristics (K<SUB>T</SUB>, K<SUB>T</SUB> and η<SUB>0</SUB>) were compared for three different ducted propellers using a Computational Fluid Dynamics (CFD) analysis, as well as an experimental test at a basin. The best shape of the duct was selected from the three types of specially designed ducts based on the CFD analysis results. The same propeller model (Kaplan type propeller) was used inside all three duct models, and the propeller open water characteristics were compared, predominantly at the design speed for an underwater vehicle. Finally, the results of the CFD test simulations for the selected duct case were verified by experimental open water tests in a towing tank.
정태환(Tae-hwan Joung),강성길(Seong-gil Kang),이성엽(Seong-yeob Lee),이다희(Dahee Lee),원해민(Haemin Won) 한국해양환경·에너지학회 2021 한국해양환경·에너지학회 학술대회논문집 Vol.2021 No.10
2018년 4월, 국제해사기구(IMO)는 국제항행을 하는 선박으로부터 배출되는 온실가스 감축을 위한 초기전략을 수립하였고, 온실가스 감축 목표를 2008년 대비 2050년까지 최소 50%로 설정하였다. 최근 IMO에서는 현존선에 대한 규제(EEXI, CII)를 도입하고, 신조선에 대해서는 온실가스 배출이 많은 일부선종과 선형에 대하여 기존의 규제(EEDI)를 강화하고 있다. 따라서 현존선의 활용을 가능한 지속하려는 선주들의 요구에 에너지 효율 개선 장치(Energy Saving Device) 활용 또는 저탄소연료(LNG, 메탄올 등)로의 부분교체(retrofit)와 함께 선상 이산화탄소 포집기술(CCS)과 무탄소 연료(암모니아, 수소 등) 추진 기술 등 다양한 기술을 검토하고 있다. 이와 함께 현재 IMO에서 논의되고 있는 시장기반조치(MBM)는 온실가스배출권 거래제를 전세계 해역으로 확신사키거나 노후선에 더 많은 탄소세를 추징하는 방식으로 시행될 것이다. 이에 대응하기 위하여 우리나라는 LNG 추진선에 대한 건조능력과 관련 기술력에서 우위에 있으므로 무탄소연료로 가기 위한 중기적 연료로서 활용하려하고 있으나, 최근 제4차 IMO GHG 연구 결과에서는 가스연료의 사용 증가에 따른 메탄의 증가를 우려하여 있으며, 이에 따라 규제가 있을 것임을 강력하게 암시하고 있다. 본 연구에서는 IMO 해양환경보호위원회(MEPC)에서 논의되고 있는 주요한 환경규제 중 특히 온실가스 배출에 대한 규제에 대한 논의 동향과 이에 대응하기 위한 기술개발 및 정책개발 현황과 그 의의를 살펴보고, 우리나라가 대응하여야 할 방향에 대하여 논의하고자 한다. In April 2018, the International Maritime Organization (IMO) established an initial strategy for reducing greenhouse gas emissions from ships traveling internationally, and set the greenhouse gas reduction target to at least 50% until 2050 compared to 2008. Recently, IMO introduced novel regulations for existing ships (EEXI, CII), and strengthened the existing regulations (EEDI) for some types of ships and ships that emit excessive greenhouse gases. Therefore, in response to the demands of ship owners who want to continue using existing ships as much as possible, use of various technologies such as Energy Saving Device or partial replacement (retrofit) to low-carbon fuel (LNG, methanol, etc.) and propulsion technologies (ammonia, hydrogen, etc.) are being reviewed. In addition, the market-based measures (MBM) currently being discussed at the IMO will be implemented as a form of greenhouse gas emission trading system. In order to respond to this, Republic of Korea is trying to use LNG fueled ship as a medium-term fuel to go to zero carbon fuelled ship because it has superiority in construction capacity and related technology for the LNG-fuelled ships. There are, however, concerns about an increase in methane, which strongly suggests that there will be regulations accordingly. In this study, among the major environmental regulations being discussed at the IMO Marine Environment Protection Committee (MEPC), the trend of discussion on the regulation of greenhouse gas emission, the status of technological and policy development to respond to the trend will be discussed.
복합재 반자율 무인잠수정(SAUV)의 내압선체 설계, 구조해석 및 내압시험 결과에 관한 검토
정태환(TAE-HWAN JOUNG),이종무(CHONG-MOO LEE),홍석원(SEOK-WON HONG),김진봉(JIN-BONG KIM),안진우(CHIN-WOO AN) 한국해양공학회 2004 韓國海洋工學會誌 Vol.18 No.4
A Semi-Autonomous Underwater Vehicle (SAUV), capable of simple work on the seabed, is under development in KRISO-KORDI. This SAUV pressure vessel is composed of fiberglass reinforced plastic (FRP), and is also manufactured to carry electronic equipment. The objective of this paper is to describe the safety check for the pressure vessel. This is achieved by conducting structural analysis and testing in a pressure tank. Strain and stress test results, under unit load, are obtained by using ANSYS in linear structural analysis. Local buckling analysis are performed with NASTRAN at the middle of the cylindrical hull. The first test, using linear structural analysis, is unsuccessful, as buckling occurred. During the second test, linear structural analysis, combined with local buckling analysis, is conducted. There is no buckling up to 250 m when both ANSYS and NASTRAN are used.
정태환(TAE-HWAN JOUNG),노인식(IN-SIK NHO),이재환(JAE-HWAN LEE),이종무(CHONG-MOO LEE),Tadahiro Hyakudome,Karl Sammut 한국해양공학회 2007 韓國海洋工學會誌 Vol.21 No.6
In this paper, the authors demonstrate a new idea to take the place of the real pressure vessel test, which should be carried out in a high pressure experiment unit before the real sea trial test. The idea is to make a pressure vessel model as a replica of the real pressure vessel test, which can reduce the cost of making a pressure vessel and large pressure experiment unit. The pressure vessel model was designedbased on linear-elastic, buckling equations and Finite Element Analysis. The manufactured pressure vessel model was investigated and monitored while the pressure test was being conducted. After the test, the result and the validity pressure vessel model as a replica of the real pressure vessel test was studied.
선박으로부터 배출되는 메탄과 후처리 장치 기술 개발 동향
정태환(Tae-hwan Joung),이성엽(Seong-yeob Lee),강성길(Seong-gil Kang),이다희(Dahee Lee),천정민(Jeongmin Cheon),하승만(Seungman Ha) 한국해양환경·에너지학회 2021 한국해양환경·에너지학회 학술대회논문집 Vol.2021 No.10
LNG(액화천연가스)는 주로 기후변화 문제를 유발하는 물질인 메탄으로 구성된다. 선박에서 배출되는 메탄은 LNG 등 가스연료를 사용할 때 메탄슬립이라는 형태로 배출된다. 메탄슬립은 LNG 주성분이자 온실가스 중 하나인 메탄이 불완전 연소되어 대기 중으로 방출되는 현상이다. LNG로 대표되는 가스연료는 탄소를 배출하지 않는 최종목표로 가기 위한 과도기적 연료이다. LNG는 연소시 다른 화석연료보다 적은 이산화탄소를 배출하지만 불완전 연소시 배출되는 메탄은 이산화탄소보다 지구온난화 지수가 높아 문제가 된다. 최근 제4차 IMO GHG 연구 결과에서는 가스연료의 사용 증가에 따른 메탄 배출의 증가를 우려가 있으며, 이에 따라 메탄배출에 관한 IMO 규제가 도입될 것임을 강력하게 암시하고 있다. 따라서 메탄슬립은 LNG를 선박용 내연기관으로 사용할 경우 LNG가 가진 치명적 약점이며, 이를 극복하기 위하여 다양한 연구개발이 수행되고 있다. 본 연구에서는 LNG 운반선 및 LNG 연료추진 선박에서 발생하는 메탄 배출의 메커니즘을 파악하고, 메탄의 배출을 저감하기 위한 기술개발 현황과 국제사회에서의 논의동향을 살펴보았다. Natural gas mainly consists of methane, a substance which causes climate change. Methane exhausted by ships is usually released in the form of methane slip while gas fuels such as LNGs are consumed. Gas fuels such as LNG are considered to be one of the transitionary fuels for zero-emission energy source. Although LNG releases fewer amount of carbon dioxide during combustion compared to other types of fossil fuels, methane released in the form of methane slip during incomplete combustion has more detrimental effect on global warming than same amount of carbon dioxide, which is problematic. While there is no regulation mentioning release of methane from ships, according to the 4th IMO GHG study, there is a growing concern about the increase of methane emission caused by the LNG fuelled ships, and implies that IMO regulation addressing methane emission will be introduced in near future. Therefore, methane slip is a critical weak point of LNG fueled ship, and to resolve this issue, many researches and developments are being conducted. This research identifies the mechanism of methane emission in LNG carriers and LNG fueled vessels and examines the status of technical development in reducing methane emission and international discussion trend.