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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.
인간 상피성장인자 유전자 발현 유전자변형 콩의 생태계 침입성 평가
김도영(Do Young Kim),엄민식(Min Sik Eom),김혜진(Hye Jin Kim),백인순(In-Soon Pack),박정호(Jung-Ho Park),박기웅(Kee Woong Park),남경희(Kyong-Hee Nam),오성덕(Sung-Dug Oh),김재광(Jae Kwang Kim),서주석(Ju Seok Seo),김창기(Chang-Gi Kim) 한국잡초학회·한국잔디학회 2020 Weed & Turfgrass Science Vol.9 No.2
유전자변형(genetically modified, GM) 작물의 생태계 침입성 또는 잡초화 가능성은 환경 측면에서 주요 우려 사항의 하나이다. 인간 상피성장인자 유전자(egf, igf-1, trx)를 발현하는 GM 콩 3개 이벤트가 재배관리되지 않는 환경에서 지속할 수 있는지 여부를 평가하고, 토양에 매몰된 종자의 활력을 조사하기 위해 본 연구를 수행하였다. GM 콩과 비변형 콩종자를 2017년 6월에 파종하고 연구기간 동안 물과 병해충 및 잡초 관리를 하지 않은 채 시험구에 출현한 콩 식물체 수를 조사하였을 때 GM 콩과 비변형 콩 식물체는 생장하고 종자 생산도 하였지만 17개월까지만 개체군을 유지할 수 있었다. 콩 종자를 2017년 11월에 매몰한 뒤 4, 6, 8, 10개월 후에 활력을 조사하였다. GM 콩과 비변형 콩 종자 모두 월동은 가능했지만, 모든 종자는 6개월 이내에 활력을 잃었다. 이와 같이 GM 콩과 비변형 콩 모두 정착에 성공하지 못했으며, 수명이 짧은 콩 종자는 일시적으로만 토양종자은행을 형성하였다. 따라서 3개 GM 콩 이벤트가 생태계에서 침입식물 또는 잡초가 될 가능성은 거의 없을 것으로 판단된다. The invasiveness or weediness of genetically modified (GM) crops is considered as one of the major environmental concerns regarding the cultivation of these crops. This study was conducted to evaluate whether three events of GM soybeans expressing human epidermal growth factor gene (egf , igf-1 , or trx ) can persist in the environment without cultivation management and to determine the viability of their seeds buried in soil. Seeds of GM and non-GM soybean were sown in June 2017, and the number of soybean plants grown in the plots was counted. During the study period, water and pest management were not applied in the plots. Both GM and non-GM soybean plants were able to grow and produce seeds; however, they maintained their populations only for up to 17 months. The GM and non-GM soybean seeds were buried in November 2017, and their viability was measured 4, 6, 8, and 10 months after seed burial. Both GM and non-GM soybean seeds were able to overwinter. However, they lost viability within 6 months. GM and non-GM soybeans could not be successfully established in the environment, and short-lived soybean seeds could form only a transient soil seed bank. Therefore, GM soybean events are highly unlikely to become invasive plants or weeds in the ecosystem.
권순길,김창기,윤상용,Kwon, Soon-Kil,Kim, Chang-Kee,Yun, Sang-Yong 한국군사과학기술학회 2011 한국군사과학기술학회지 Vol.14 No.6
For developing the ignition device for the interceptor of Korean active protection system, the design parameters of the ignition device which should have a short ignition delay time and sufficient energy for propellant ignition were studied. The electric primer instead of mechanical primer was adopted for deceasing delay time, and ignition code was used for decreasing the time difference of flame propagation from the flame holes. The developed ignition device showed the ignition delay time of a few ms. When the designed ignition device was applied to the open-type propulsion devices, the stable interior ballistic characteristic was showed in a firing test.
박희용,김창기,Kim, Hi Yong,Kim, Chang Kee 대한설비공학회 1991 설비공학 논문집 Vol.3 No.1
An experimental result for heat transfer of pulsating turbulent pipe flow was presented under the condition of fully developed dynamic regime and uniform wall heat flux. Experiments were performed at following conditions ; Inlet time-averaged Reynolds number varied from 5000 to 11000; The peak pressure fluctuation were 1.3, 2.3 and 3.5 percent of the mean pressure; Pulsating frequency ranged from 53 Hz to 320 Hz The measurements showed that the effect of pulsation on local heat transfer is greater at downstream, in which pulsating source exists, than upstream and the heat transfer rate, averaged over the pipe length, was higher or lower than in an equivalent non-pulsating flow according to the pulsating conditions. In addition, the significant change of heat transfer rate was observed in acoustically resonant conditions, when the pulsating frequency of the flow corresponded to the pipe natural frequency.
그리드핀을 적용한 작은 세장비를 갖는 자탄의 천음속 공력특성 전산해석
유재헌,김창기,최윤정,임예슬,Yoo, Jae-Hun,Kim, Chang Kee,Choi, Yoon Jeong,Lim, Ye Seul 한국시뮬레이션학회 2019 한국시뮬레이션학회 논문지 Vol.28 No.2
작은 세장비(aspect ratio)를 갖는 형상의 자탄(sub-munition)은 자유낙하 시 비행 자세 안정성이 불량하고 항력조절이 어렵다. 이러한 문제점을 해결하기 위해 일반적인 비행 날개 대신 그리드핀이라고 불리는 핀을 설계하여 자탄에 적용하였다. 우선 자탄의 기본모델을 설정하고, 해당 모델에 대한 자유낙하 하는 천음속(transonic) 조건에서의 전산해석이 수행되었으며 풍동시험을 통해 전산해석 결과를 검증하였다. 기본모델의 경우 요구되는 수준의 높은 항력은 얻었으나 자세 안정성이 확보되지 않았다. 이를 개선하기 위해 그리드핀의 설계변수 중 하나인 웹 두께(web-thickness)를 변경하여 2종의 핀을 추가로 설계하였으며 해당 설계안에 대한 전산해석을 수행하였다. 수행 결과, 웹 두께가 가장 얇은 조건에서 자세 안정성이 가장 우수하게 확보되었으며 항력계수도 큰 값을 유지하였다. 해석 결과를 기반으로 그리드핀 설계를 완료하고, 자탄에 대한 공력자료를 확보하여 이를 토대로 자탄의 탄도를 예측할 수 있는 기반이 마련되었다. 또한, 그리드핀이 다양한 형태의 비행체와 탄에 사용될 수 있을 것으로 기대된다. A sub-munition which has low aspect ratio does not have flight stability and control of drag force under free-fall condition. In order to satisfy those problems, fin, which is called grid-fin, is designed instead of conventional flight fins and adapted to the sub-munition. The base model of the sub-munition is firstly set and numerical simulation of the model is conducted under transonic condition that is free-fall range of the sub-munition. Wind test is secondly performed to verify the simulation result. The result shows that grid fin adapted sub-munition has high drag force, but the flight stability is still needed. In order to enhance the flight stability, two additional grid-fins are designed which modify web-thickness and numerical simulations of modified models are conducted. As the results, the thinnest web-thickness grid-fin has the highest flight stability and still maintains high drag coefficient. Based on these results, design of grid-fin adapted sub-munition is completed, the path trajectory of the sub-munition can be predicted with acquired aerodynamic datum and it is expected that grid fin can be used to various shape of the flight vehicle and bomb.