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김기홍(Kihong Kim),이경철(Kyung-Cheol Lee),곽민철(Min-Cheol Gwak),김용현(Yong-Hyeon Kim),도영대(Young-Dae Doh),김창기(Chang-Kee Kim),유지창(Ji-Chang Yoo),여재익(Jai-Ick Yoh) 한국추진공학회 2009 한국추진공학회 학술대회논문집 Vol.2009 No.11
고체 로켓 추진제로 널리 사용되는 물질은 AP/HTPB 복합추진제이다. 고체 로켓 주위에 열 하중이 가해진다면(화재 등) 추진제가 발화할 수 있고, 사고의 원인이 된다. 본 연구에서는 AP/HTPB 복합추진제의 주위에 열 하중을 가함으로써 AP/HTPB의 발화특성을 확인해 보았다 The AP/HTPB composite propellant is a common choice for solid rocket propulsion. The externally heated rocket via fires, for instance, can cause the energetic substance to ignite, and this may lead to a thermal runaway event marked by a severe explosion. In order to develop preventive measures to reduce the possibility of such accidents in propulsion systems, we investigate the ignition and initiation properties of AP/HTPB propellant.
다차원 시뮬레이션을 활용한 단일 PETN 결정의 이방성 점화 현상 수치 연구
곽민철(Min-cheol Gwak),이웅현(Woong-Hyun Lee),김기홍(Kihong Kim),여재익(Jai-ick Yoh) 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.12
Ignition & Growth(I&G) 모델과 JWL++ 모델을 비롯한, 일반적인 고폭화약의 화학반응식은 점화 시, 충격이 가해지는 방향에 의존하지 않는 등방성 화약이라는 전재 하에 수치 해석에 활용되어 왔다. 하지만, 단일 결정체로서의 펜타에리트리톨 테트라니트레이트(PETN)의 경우, 충격에 의한 점화에 있어서 민감한 방향(<110>방향)과 둔감한 방향(<100>방향)을 동시에 가지기 때문에 수치 해석 시 점화의 방향성이 고려되어야 한다. 본 연구에서는 다차원 해석을 통하여, 단일 결정체로서의 PETN의 이방성 점화 현상을 수치해석하였다. 이를 통해 실험 결과와의 비교 검증을 수행하였으며, 2차원/3차원 문제를 활용하여 충격 방향에 따른 점화 유무를 압력장과 스트레인장을 통하여 확인하였다. A standard numerical approach in chemical reaction of high explosives such as I&G model and JWL++ model assumes perfect isotropy or impact direction independence to the ignition of an explosive crystal. However, it is a single crystal Pentaerythritol tetranitrate(PETN) that need to consideration of directional nature in numerical simulation because PETN has sensitive direction (<110> direction) and insensitive direction (<100> direction) in impact ignition. In this paper, we present an anisotropic detonation of a single crystal PETN using multi-dimensional simulations. Through two- to three-dimensional loading problem, we validate the model in comparison to the experimental data and confirm possibility of ignition along impact direction using pressure and strain fields.
Son Kihong,Kim Jin Sung,Kao Chien-Min,Cho Seungryong 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.81 No.11
A real-time dose-guidance is highly desirable for monitoring the accuracy of the radiation treatment during irradiation. We present a sequentially processed image reconstruction algorithm (SPIRA) for in-beam TOF-PET that has the potential to provide concurrent imaging of the positron distributions from list-mode TOF-PET data in particle therapy. The SPIRA employs the maximum-likelihood (ML) criterion and reconstructs an image in the continuous-coordinate event space. In parallel, a serial processor (SP) is adopted to support concurrent imaging. The algorithm has been applied to computer simulation data generated for its potential use in in-beam TOF-PET monitoring of dose distributions in proton therapy, including a full-ring system and a dual-head partial-ring system. We considered various coincidences resolving times (CRTs) for the systems including 300 ps and 600 ps. Two opening angles Ø, 45 and 90°, were considered in the partial-ring geometry. The images generated by the SPIRA appear to provide better resolution and contrast recovery than by the conventional image reconstruction method in which the events are simply placed at the computed positions based on the TOF measurement. We believe that SPIRA can be useful for in vivo treatment verifcation in a real-time dose-guided particle therapy.
수소가 은 촉매 기반 HC-SCR 성능에 미치는 영향에 대한 실험적 연구
김기홍(Kihong Kim),전광민(Kwang Min Chun),송순호(Soonho Song) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5
Hydrocarbon selective catalytic reduction(HC-SCR) system has a potential to reduce NOx emission in diesel exhaust without complex constructions or infrastructures. But low temperature activities of HC-SCR over silver catalyst are still be a problem. According to previous research, hydrogen addition to the system could be a candidate to solve this problem. Adding hydrogen into the system with hydrocarbons as reductans over silver/alumina catalyst could improve the NOx reduction efficiency at low temperature range which has been reported recently in many researches. In this diesel engine bench test, the hydrogen effect for NOx reduction efficiency over silver/alumina catalyst with on-board diesel fuel as a reducing agent was investigated as functions of temperature, C/N ratios and H₂/N ratios.