• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.768-769
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• 2015

본 논문에서는 3상, 1250MVA, 345kV급 전력용 변압기의 하우징 영역에 대한 온도상승 연구를 유한요소법과 시험을 통하여 수행하였다. 하우징 영역에 대한 전자계 요한요소 해석을 통해 와전류 손실을 수행하였고, 이를 열원으로 하여 변압기 내 외부 냉각조건을 고려하여 온도상승 분포와 최고온도 상승 값을 해석하였다. 이를 제작된 변압기를 대상으로 온도센서 및 열화상 카메라를 이용한 측정 데이터와 비교하여 검증하였다.

• Journal of Advanced Marine Engineering and Technology
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• v.6 no.2
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• pp.51-68
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• 1982

A method of calculation of temperature distribution during welding was studied and compared with the existing formulas and experimental results. In contrast to the existing formulas which are founded on the suppositions that the heat source is a point and that the dimensions of welded pieces are infinite, we tried to make the distribution of calorific density of heat source approach reality more closely, so we considered it as a normal distribution of Gauss, and we presented the formulas for calculation of temperature during welding. We also used the principle of superposition for the temperature calculations of finite welded pieces. We compared the formulas presented in this paper with the existing formulas by calculations for the welding of various materials, and considerable differences around the heat source were convinced. The thermal cycles of various points were traced through the welding experiments for the mild steel, and they were compared with the results of calculations.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.8
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• pp.162-169
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• 1999

Fourier heat conduction law becomes invalid for the situations involving extremely short time heating, very low temperatures and fast moving heat source(or crack), since the wave nature of heat propagation becomes dominant. For these conditions, the modified heat conduction equation with the finite propagation speed of heat in the medium could be applied to predict heat flux and temperature distributions. In this study, temperature distributions at the vicinity of a very fast moving heat source are investigated numerically. Thermal fields are characterized by thermal Mach numbers(M) defined as the ratio of moving heat source speed to heat propagation speed in the solid. In the transonic and supersonic ranges($M{\ge}1$), thermal shocks are shown, which separate the heat affected zone from the thermally undisturbed zone.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.751-752
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• 2006

최근 전력용 변압기의 고효율, 소형화 추세에 따라 권선의 단위면적당 열발생률이 증가하고 있으며 이는 변압기의 수명과 단락사고에 직결되는 중요한 문제로 대두되고 있다. 본 논문에서는 단순화한 2차원 전력용 변압기 모델의 계산 시간을 줄이기 위해 복합격자(Hybrid mesh) 생성기법을 적용하여 모델링하고 유한요소법을 이용한 자계해석으로 권선과 철심의 Joule's loss를 계산하였다. 계산된 열원으로 전력용 변압기의 최고점의 온도와 열적 특성을 파악하고자 CFD algorithm을 이용하여 변압기 내부의 온도분포를 예측하였다.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.34-37
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• 1997

The nonuniform thermal sources of a squirrel cage induction motor are obtained from the losses calculated by the nonlinear complex finite element analysis considering skew effects. Then, temperature rises of the motor are calculated using thermal equivalent network analysis and compared with some experimental values.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1242-1247
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• 2010

In this study, the heat source distributions at the end side and the center of the electrode are analyzed to estimate the electrical stress due to the harmonics from the nonlinear loads. The governing equation at the analysis area of low voltage condenser are numerically solved using the finite element software package to analyze the effects of heat source distribution due to the 5th and 7th harmonics, which can exist normally in the distribution network and can be applied to the low voltage condenser. Finally, the heat source distribution from the harmonics is compared and analyzed with the heat source distribution from the fundamental component of the applied voltage.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.4
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• pp.726-733
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• 1989

Conduction heat transfer in heat spreaders with concentrated heat sources is analyzed by finite element method calculation and the results are compared to analytical solutions for simplified cases. The local temperature rise is dependent on the heat flux, thermal conductivity of the spreader material, and the contact size of the heat source. The effect of the adjacency of other heat sources is also examined.

• Journal of the Korean earth science society
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• v.26 no.1
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• pp.93-105
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• 2005

Climatological characteristics in the variation of soil temperatures in Korea were investigated using Korea Meterological Administration's observation data. And the impacts of soil moisture on the variation of soil temperature were examined using observed precipitation data. The climatological averages of soil temperatures are ranged from 14.4 to $15.0^{\circ}C$ regardless of depths. And they showed an latitudinal gradient with a warm temperature at the southern region and 'U' shape as in the air temperature with a high value along the coastal region. The relatively higher heat capacity and low conductivity of soil compared to those of the air resulted in the significant delay of the maximum and minimum date with depth. As a results, soil acts as a heat source during winter while a heat sink during summer. Global warming and urban heat island have increased the soil temperatures with an average rate $0.3\~0.5^{\circ}C/10-year$ as in the air temperature during last 30 years $(1973\~2002)$. However, the warming rate is maximized during spring contrary to the winter in the air temperature. The temporal variation of soil temperatures is strongly affected by that of soil moisture through an modification of the heat capacity and heat convection. In general, the increased soil moisture clearly decreased the temporal variations and increased the deep layer soil temperatures during cold season.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.4
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• pp.405-412
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• 2004

During the irradiation tests of material and fuel rod, all components of the cylindrical structure with multiple holes act like heat sources due to high gamma heat and fission heat. The objective of this study is to formulate the general solution for the temperature distribution to estimate the thermal integrity of structure during irradiation tests. For the temperature distribution analysis, the two-dimensional heat conduction theory is used. The unmerical analysis is performed by the commercial finite element analysis code, ANSYS 6.1. If the cylindrical structure with hole number would not exceed three holes, the analysis results and finite element results are good agreement together. For the structure with four holes, the discrepancy between FE results and analysis results of the structural temperature distribution is increased.

• The Journal of Engineering Geology
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• v.3 no.3
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• pp.267-278
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• 1993

Ground-water temperature is one of the parameters for observing diarges in the state of the ground-water regime in time and space, which relate to conditions for recharge as well as the influence of various natural and man-induced fadors on the regime. Because ground-water satura tes much of the rock materiats in the upper layer of the earth's csust the water temperature reflects in part the temperature of the water-bearing rocks. The mobffity and thennal capadty of groud-waters, however, serves to redistribute some of the heat within the stratosphere and to influence the developement of the geothermal regime within this sphere. The utilization of temperature data of the study area(25 points) in the solution of hydrogeologic problems requires an understanding of some of the fundamental aspects of subsurtice temperatures. These include the depth of penetration of heat waves generated of the surtace, the rate of propagation of the waves, and the geothermal gradient in the study area of Taegu.