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엇갈림 휜을 갖는 전자기기의 열유동 모델링 및 휜 형상 최적 설계
김치원(Chiwon Kim),이관수(Kwan-Soo Lee),여문수(Moon Su Yeo) 대한설비공학회 2017 설비공학 논문집 Vol.29 No.12
Thermal and flow modeling and fin structure optimization were performed to reduce the weight of an electrical device with a staggered fin. First, a numerical model for thermal and flow characteristics was suggested, and then, the model was verified experimentally. Using the verified model, improvement in cooling performance of the cooling system through the staggered fins was predicted. As a result, 87.5% of total heat generated was dissipated through the cooling fins, and a thermal island was observed in the rotor because of low velocity of the internal air flow through the air gap. In addition, it was confirmed that the staggered fin improves the cooling performance but it also increases the total pressure drop within the cooling system, by maximizing the leading edge effect. Based on this analysis result, the effect of each design parameter on the thermal and flow characteristics was analyzed to select the main optimal design parameters, and multi-objective optimization was performed by considering the cooling performance and the fin weight. In conclusion, the optimized fin structure improved the cooling performance by 7% and reduced the fin weight by 28% without any compromise of the pressure drop.
3차원 등가 열회로망 기법을 이용한 개방형 공랭식 3상 유도전동기 열해석
김치원(Chiwon Kim),이상욱(Sangwook Lee),이관수(Kwan-Soo Lee) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
Predicting motor temperature is the most important issue according to efficiency and lifespan of a motor. Usually, equivalent thermal circuit analysis is used for predicting motor temperature, because it requires less computational resources than computational fluid dynamics (CFD). In this paper, 3 dimensional thermal equivalent circuit analysis is performed to predict temperatures of an open type air-cooled 3-phase induction motor. Unit structure for 3-D equivalent circuit is introduced. Inner and interfacial thermal resistance, sources/sink for each part of motor are calculated considering the shape of slot and copper bar. Verification is performed with CFD and experiment results. Present model shows improved accuracy comparing to previous 2-D base models.
열 사상법을 이용한 유도 기동형 동기 전동기의 비정상 3차원 열해석
김치원(Chiwon Kim),엄석기(Sukkee Um) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
This paper describes thermal modeling of a line start permanent magnet (LSPM) motor using a computational flow dynamics method. First, 2-dimensional electromagnetic design is carried out in order to comprehend heat losses at winding, stator, rotor and cage. New coupling method called Heat mapping method (HMM) will be introduced which converts 2-D information of electromagnetic domain to 3-D information of thermal domain. Transient thermal analysis under rated operating conditions is performed to identify the load saturation time and temperatures in the LSPM motor. Experimental results are collected under the same operating conditions and computational results are verified against the experimental data. Finally, thermal path analysis at a steady-state is conducted to figure out the direction and magnitude of heat flux in the LSPM motor. These results can be useful to design effective cooling systems of electrical motors.
스파크점화 가솔린기관의 전자제어기 설계 및 연소특성에 관한 실험적 연구
김치원(Chiwon Kim),한성현(Sunghyun Han),이준경(Jungkyung Lee),이종진(Jongjin Lee),김대훈(Daehoon Kim) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In this paper. the response characteristics of fuzzy controller, combustion. emission formation and performance characteristics are analyzed with changing equivalence ratio of engine operating variables. The experimental phase of this analysis was performed and analyzed with 4-stroke, spark ignited, and gasoline injected engine which was modified for this experiment by fuzzy controlled injection.
스파크 점화 기관의 흡기 조성 변화에 따른 기관 연소와 배기 특성에 관한 연구
김치원(Chiwon Kim),서병준(Byungjun Seo),오민석(Minsuck Oh),정용관(Yonggoan Jung),이병호(Byungho Lee) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.5_1
In a conventional spark ignition engine the fuel and air are premixed together, and, by a spark ignition, in flamed. Therefore the state and composition of air-fuel mixture are very important in the combustion and emission.<br/> In this study, the combustion characteristics and exhaust emissions werw tested and analyzed with changing the oxygen volumetric fraction(O₂enriched inlet air), in order to improve the combustion and volumetric fraction burned by numerical calculation and experimental method.<br/> According to increase of oxygen volumetric fraction, the maximum cylinder pressure and the rate of pressure rise were increased, the ignition delay and combustion duration were shortened, and the composition of carbon monoxide and unburned hydrocarbon were lower, but those of nitric oxides were in reverse.
김홍래(Hongrae Kim),이우송(Woosong Lee),김치원(Chiwon Kim),한성현(Sunghyun Han) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In this paper, we developed a Windows NT version off-line programming system which can simulate a track vehicle model in 3D graphics space. The track vehicle was adopted as an objective model. The interface between users and the off-line program system in the Windows 98's graphic user interface environment was also studied. The developing language is Microsoft Visual C++. Graphic libraries, OpenGL, by Silicon Graphics, Inc. were utilized for 3D Graphics.<br/>
김광대(Kwangdae Kim),서병준(Byungjun Seo),오민석(Minsuck Oh),김치원(Chiwon Kim) 한국자동차공학회 2005 한국자동차공학회 지부 학술대회 논문집 Vol.- No.-
With the rapid development of modern industrialization, human begins have been exposed to environmental pollution and have been paying special attention to preventing it. Recently, in the representative research of reducing NOx as well as improving Compression Ignition Engine performance, it is being regarded as important to correctly understand the high pressure spray to determine the initial conditions of combustion characteristics and the ultimate interior design of a combustion chamber. For the CI engine, optimizing the ultimate fuel injection timing according to the operating conditions is of great importance, because the fuel injection timing has considerable influence on the combustion characteristic and emission formation. The purpose of this research is to find thc optimal combustion characteristics and reduce the exhaust emission based on the wall impingement with changing by the important combustion-related factors through the numerical analysis methods.