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안현모(Hyun-Mo Ahn),한성진(Sung-Chin Hahn) 대한전기학회 2009 대한전기학회 학술대회 논문집 Vol.2009 No.7
본 논문에서는 온도상승의 열원이 되는 권선과 철심의 전력손실을 유한요소법을 이용한 전자계해석과 스타인메츠실험식으로 산정하였다. 온도에 대한 자연대류 열전달계수를 산정하여 경계면에서의 경계조건으로 적용하였다. 열전달 해석을 위해 전력용변압기를 3차원 형상으로 모델링한 후 유한요소법을 이용해 권선과 철심에서의 온도분포를 해석하였다.
전자계-열계 결합해석에 의한 전력용 변압기의 열전달 해석
안현모(Hyun-Mo Ahn),오연호(Yeon-Ho Oh),한성진(Sung-Chin Hahn) 대한전기학회 2009 전기학회논문지 Vol.58 No.11
In this paper, we dealt with the electro-thermal coupling analysis for temperature prediction of power transformer. Heat transfer coefficient are calculated using Nusselt number in accordance with heat source generated from transformer windings and core materials. The calculated temperatures in power transformer were compared to those of measured ones and showed good agreement. This coupling method using heat transfer coefficient can be used at the design stage of power transformer efficiently.
안현모(Hyun-Mo Ahn),오연호(Yeon-Ho Oh),한성진(Sung-Chin Han) 대한전기학회 2010 대한전기학회 워크샵 Vol.2010 No.11
본 논문에서는 배전용 변압기의 온도분포를 예측하기 위하여 3차원 열유동 해석을 다루었다. 해석의 정확도를 향상시키기 위해 방열판과 권선의 형상을 실제의 형상으로 모델링하였으며, 전자계해석을 통해 온도상승을 일으키는 권선과 철심의 전력손실을 계산하였다. 해석시간을 단축시키기 위해 변압기와 공기의 경계면에 대류열전달계수를 적용하였고, 6면체 정렬격자(Hexahedron)로 격자를 생성하여 해의 수렴성을 향상시켰다.
전력용 변압기의 온도상승 예측을 위한 전자계-열계 결합해석기법 연구
안현모(Hyun-Mo Ahn),김민수(Min-Soo Kim),송재성(Jae-Sung Song),한성진(Sung-Chin Hahn) 대한전기학회 2011 전기학회논문지 Vol.60 No.10
This paper deals with coupled electromagnetic-thermal field analysis for thermal fluid analysis of oil immersed power transformer. Electric power losses are calculated from electromagnetic field analysis and are used as input source of thermal field analysis based on computational fluid dynamics(CFD). Particularly, In order to accurately predict the temperature rise in oil immersed power transformer, the thermal problem should be coupled with the electromagnetic problem. Moreover, to reduce analysis region, the heat transfer coefficient is applied to boundary surface of the power transformer model. The coupling method results are compared with the experimental values for verifying the validity of the analysis. The predicted temperature rises show good agreements with the experimental values.
전자계-기계계 결합해석에 의한 건식변압기의 단락강도 예측
안현모(Hyun-Mo Ahn),한성진(Sung-Chin Hahn) 대한전기학회 2011 전기학회논문지 Vol.60 No.2
This paper deals with the coupled electromagnetic-mechanical field analysis for short-circuit electromagnetic force of the dry-type transformer. The short-circuit currents are calculated using external circuit in accordance with short-circuit test equipment. According to short-circuit current, the generated magnetic leakage flux density in dry-type transformer model is calculated by finite element method. The radially-directed electromagnetic forces in windings are calculated using electromagnetic field analysis and then axially-directed electromagnetic forces in windings are calculated using electromagnetic-mechanical field analysis. The calculated axially-directed electromagnetic forces in high voltage winding are compared to those of measured ones and showed good agreement with experimental results.
피복아크용접을 이용한 압연강재에 대한 용접성 평가에 대한 연구
안현모(Hyun Mo Ahn),이종식(Jong Sick Lee) 산업기술교육훈련학회 2017 산업기술연구논문지 (JITR) Vol.22 No.4
This paper deals with evaluation of weldability for Rolled carbon steel(SS400 and SM45C) Using SMAW, in which weldability test specimens were categorized into A, B, C type, respectively, for the purpose of weldability evalution, mechanical properties of the specimens between the whiles similar and dissimilar materials were then investigated, and the results obtained through observation were macroscopically compared and analyzed. Under each experiment condition those mechanical properties of the welded specimens were furtherly analyzed for inlcluding the hardness test for each specimen by dividing the welded are the metal part, the heat affected zone, and the base part, Hardness was shown to be the highest in the heat affected zone while there was no significant difference between the welded metal and base metal. Tensile strength and yield strength values were enhanced on all the specimens. Both of macroscopic and microscopic examination revealed notable changes in the heat affected zone seen in the microscopic structure of similar and dissimilar materials. The larger the amount of carbon gets, the greater the amount of pearlite (black part) together with the excessive cementite tend to apper. The texture of the welded part was similar to that of the base material and the microstructure of the crystal grain turned out to be refined.