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자기유체역학 코드를 이용한 축 대칭 엑스 핀치 플라즈마 구조의 2차원 전산해석
변상민,나용수,정경재,김덕규,이상준,이찬영,함승기,류종현,Byun, Sangmin,Na, Yong-Su,Chung, Kyoung-Jae,Kim, Deok-Kyu,Lee, Sangjun,Lee, Chanyoung,Ham, Seunggi,Ryu, Jonghyeon 한국군사과학기술학회 2021 한국군사과학기술학회지 Vol.24 No.2
This paper deals with the computational work to characterize the formation and pinching of a plasma in an X-pinch configuration. A resistive magnetohydrodynamic model of a single fluid and two temperature is adopted assuming a hollow conical structure in the (r,z) domain. The model includes the thermodynamic parameter of tungsten from the corrected Thomas-Fermi EOS(equation of state), determining the average ionization charge, pressure, and internal energy. The transport coefficients, resistivity and thermal conductivity, are obtained by the corrected Lee & More model and a simple radiation loss rate by recombination process is considered in the simulation. The simulation demonstrated the formation of a core-corona plasma and intense compression process near the central region which agrees with the experimental observation in the X-pinch device at Seoul National University. In addition, it confirmed the increase in radiation loss rate with the density and temperature of the core plasma.
미래 주행정보를 이용한 하이브리드 차량의 주행 최적화 전략
변상민(Sangmin Byun),김남욱(Namwook Kim),임원식(Wonsik Lim),차석원(Suk-Won Cha) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
There are a number of strategies for the energy management of HEV's(hybrid electric vehicle) to improve fuel economy. This paper presents an optimal cruise control strategy using future driving information. The method proposed in this paper is based on the PMP(Pontragyn's Minimum Principle) algorithm as a viable real-time strategy. This control strategy has been applied to a parallel HEV system. To analyze the vehicle performance and fuel consumption, we used backward HEV simulator. Also, there are some practical applications which is based on the results provided by the PMP algorithm.
관성 핵융합의 군사적 의의와 고에너지밀도 플라즈마 시뮬레이션 결과
변상민(Sangmin Byun),나용수(Yong-Su Na) 한국해군과학기술학회 2020 Journal of the KNST Vol.3 No.1
Magnetic confinement, inertial confinement, and gravitational confinement are widely known for realizing nuclear fusion. Among them, Inertial confinement fusion(ICF), which is the origin of the hydrogen bomb, have been widely performed by several representative national laboratories such as Lawrence Livermore Laboratory(US), Lebedev Physical Institute(Russia), etc, for a long history. However, ICF in domestic is rarely studied due to the confidentiality and other various restriction. Considering the present nuclear threat in the Korean peninsula and national security environment, ICF should be actively studied and supported in the meaning of national security. The paper briefly outlines the origin of ICF and introduce high energy density plasma(HEDP), describes the laser ablation and wire implosion plasma. Also, pertinent simulation result using resistive MHD code will be shown with governing equation and physics model. Finally, the applications of ICF in defense will be introduced and underly the potential of the application in defense.
PMP를 이용한 Plug-in 하이브리드 차량의 주행 최적화 전략
변상민(Sangmin Byun),김남욱(Namwook Kim),박영일(Young-il Park),차석원(Suk-Won Cha) 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4
A control concept based on PMP(Pontragyn's Minimum Principle), which produces necessary conditions for an optimal control, can be adapted to optimal cruise control for PHEV(Plug-in hybrid electric vehicle), and the concept has many advantages comparing to DP(Dynamic programming). In HEV optimal problems, the DP requires a great of database to find out an optimal trajectory, whereas the PMP can save calculating time and efforts to obtain the optimal trajectory. In this study, three PHEV control strategies, a charge depleting-sustaining strategy, a PMP optimal control strategy, and a charge sustaining-depleting strategy, are analyzed by both DP method and PMP method. Especially, in the PHEV system, we can find out a global optimal control solution when we set an appropriate value of costate in PMP. This paper also demonstrates results solved from PMP are closely related to optimal control results from DP..
등가 연비 개념에 기반한 하이브리드 자동차의 연비 평가 방법 연구
오창은(Chang Eun Oh),김남욱(Namwook Kim),변상민(Sangmin Byun),박영일(Yoeng-il Park),차석원(Suk-Won Cha) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
The conventional fuel economy evaluation method of the hybrid electric vehicle requires that final SOC have to be same with the initial SOC to minimize the effect of usage of battery charge. It can be applied to backward type controller, but it is difficult to apply it to forward type controller. So in this paper, a new method of fuel economy evaluation method of the forward type hybrid electric vehicle controller using the concept of equivalent fuel consumption of fuel and SOC.
Pontryagin’s Minimum Principle (PMP)를 이용한 하이브리드 전기차의 주행 제어 최적화
김남욱(Namwook Kim),임원식(Wonsik Lim),오창은(Chang Eun Oh),변상민(Sangmin Byun),차석원(Suk Won Cha) 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4
Several optimal control ideas for Hybrid Electric Vehicles (HEVs) were proposed in the literature. The representative optimal concept based on the bellman’s optimality, Dynamic Programming, guarantees a global optimal solution which could be obtained from an optimal field. In this paper, we suggest the Pontryagin’s minimum principle as an optimal control concept, in which the principle produces necessary conditions that the optimal control trajectory must satisfy. From a static model, the optimal results solved from PMP show that the results are really close to the results solved from DP, which should be supposed to be a global optimal solution. The differences between the results solved from PMP and the results solved from DP are only under 1 %. By the optimal control concept, PMP, we could build a real-time optimal controller because the technique is fundamentally based on an instantaneous optimal concept, which means that the control idea based on PMP is very useful if we have an intelligent model to approximate the costate in real-time driving.