• Journal of Welding and Joining
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• 제8권4호
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• pp.58-68
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• 1990

The formation of thermal stresses by plasma spraying is generally considered as adverse. Therefore, the knowledge of stress distribution in the deposited layer during and after plasma spraying will be of special interest. In this study finite difference heat transfer analysis and finite element stress analysis were carried out to predict the change of stress distribution in the plasma coated layer with the variations of preheat temperature, number of scan, particle size, and bond coat. The results of the numerical analysis were as follows: 1) Transient stresses developed in the coated layer were up to the level of yiedl strength at the temperature. 2) The tensile stresses were developed in the deposited layer and the surface of the substrate, but the compressive stresses were developed in the rest of the substrate. 3) Transient and residual stresses were significantly affected by the preheat temperature. 4) The variations of temperature of powder particle and number of torch scan changed tensile stress distribution, but made no difference on the magnitude of the stresses. 5) Bond coated layer reduced the stree level of deposited layer.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.584-589
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• 2008

It is known that slab thermal storage which uses concrete slab as thermal material is effective in the load leveling and using the nighttime electric power. The temperature distribution is not constant in plenum in thermal storage time by beams, ducts such as several factor. It is considered that this fact will effect on efficiency of thermal storage and indoor thermal environment. The purpose of this paper is to examine the thermal environment inside plenum. A macro model was made for the analysis of indoor thermal environment as the first step. The flow rate distribution and temperature distribution of object room model was examined by use of basic equations such as airflow by the pressure difference between unit cells, heat flow by air and heat transfer.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
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• pp.441-444
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• 2004

Each electrical apparatus radiates various infrared as the condition of surface and load current. Because heat distribution of the apparatus changes as the condition, it is able to analyze the condition of the apparatus by using the distribution. However, methods having been used to measure the heat distribution cannot compare normal condition with abnormal, and the apparatus has diagnosed by intuition. This paper deal with a program that is able to analyze changed temperature distribution. The program is to analyze temperatures on pixels in selected region of interest or position and is able momently and logically to analyze condition of the apparatus. The results are able to apply to a on-line monitoring system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1675-1677
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• 2005

In case of attaching thermoelectric module and heat source, the polymer sheet is attached on the $AL_{2}O_3$ plate, which Is cold and hot side of thermoelectric module, in order to enhance mechanical safty of the system. It is impossible to calculate the exact distribution of temperature and flow pattern of inner gap of thermoelectric module. Therefore CFD(Computational Fluid Dynamics) analysis was executed to determine the thermo-fluid phenomena and distribution by Fluent. As the result of these analysis, heat transfer was dominated by conduction and the difference of temperature was linear distribution according to the thickness of polymer sheet.

• 한국자동차공학회논문집
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• 제16권1호
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• pp.64-70
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• 2008

Temperatures of engine head and liner depend on many factors such as spray and combustion process, coolant passage flow and engine related structures. To estimate the temperature distribution of engine structure, multi-dimensional computational fluid dynamics (CFD) codes have been mainly adopted. In this case, it is of great importance to obtain the realistic wall temperature distribution of entire engine structure. In the present work, a CFD-FEM coupling methodology was presented to address this demand. This approach was applied to a real large-size marine diesel engine. CFD combustion and coolant flow simulations were coupled to FEM temperature analysis. Wall heat flux and wall temperature data were interfaced between combustion simulation and solid component temperature analysis via translator by a commercial CFD package named FIRE by AVL. Heat transfer coefficient and surface temperature data were exchanged and mapped between coolant flow simulation and FEM temperature analysis. Results indicate that there exists the optimum cell thickness near combustion chamber wall to reasonably predict the wall heat flux during combustion period. The present study also shows that the effect of cell refining on predicting in-cylinder pressure during combustion is negligible. Hence, the basic guidance on obtaining the wall heat flux needed for the reasonable CFD-FEM coupling analysis has been established. It is expected that this coupling methodology is a robust tool for practical engine design and can be applied to further assessment of the temperature distribution of other engine components.

• Asian Journal of Atmospheric Environment
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• 제6권2호
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• pp.127-135
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• 2012

Urbanization has led to a reduction in green spaces and thus transformed the spatial pattern of urban land use. An increase in air temperature directly affects forest vegetation, phenology, and biodiversity in urban areas. In this paper, we analyze the changing land use patterns and urban heat distribution (UHD) in Seoul on the basis of a spatial assessment. It is necessary to monitor and assess the functions of green spaces in order to understand the changes in the green space. In addition, we estimated the influence of green space on urban temperature using Landsat 7 Enhanced Thematic Mapper Plus (ETM+) imagery and climatic data. Results of the assessment showed that UHD differences cause differences in temperature variation and the spatial extent of temperature reducing effects due to urban green space. The ratio of urban heat area to green space cooling area increases rapidly with increasing distance from a green space boundary. This shows that urban green space plays an important role for mitigating urban heating in central areas. This study demonstrated the importance of green space by characterizing the spatiotemporal variations in temperature associated with urban green spaces.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.225.1-225.1
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• 2010

Within recent years attention has been focused on the method of hydrogen storage using metal hydride reactor due to its high energy density, durability, safety and low operating pressure. In this paper, a numerical study is carried out to investigate the coupled heat and mass transfer process for absorption in a cylindrical metal hydride hydrogen storage reactor using a newly developed model. The simulation results demonstrate the evolution of temperature, equilibrium pressure, H/M atomic ratio and velocity distribution as time goes by. Initially, hydrogen is absorbed earlier from near the wall which sets the cooling boundary condition owing to that absorption process is exothermic reaction. Temperature increases rapidly in entire region at the beginning stage due to the initial low temperature and enough metal surface for hydrogen absorption. As time goes by, temperature decreases slowly from the wall region due to the better heat removal. Equilibrium pressure distribution appears similarly with temperature distribution for reasons of the function of temperature. This work provides a detailed insight into the mechanism and corresponding physicochemical phenomena in the reactor during the hydrogen absorption process.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1146-1151
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• 2004

Measurements of OH chemiluminescence in an atmospheric pressure, laboratory-scale dump combustor at equivalence ratios ranging from 0.63 to 0.89 were reported. The signal from the first electronically excited state of OH to ground state was detected through a band-pass filter with an ICCD. The objectives of this study are two: One is to see the effects of equivalence ratio on global heat release rate and local Rayleigh index distribution. To get the local Rayleigh index distribution, the line-of-sight images were inverted by tomographic method, such as Abel de-convolution. Another aim is to investigate the validity of using OH chemiluminescence acquired with an ICCD as a qualitative measure of local heat release. For constant inlet velocity and temperature, the overall intensities of OH emission acquired at different equivalence ratio showed periodic and higher value at high equivalence ratio. OH intensity averaged over one period of pressure increased exponentially with equivalence ratio. Local Rayleigh index distribution clearly showed the region of amplifying or damping the combustion instability as equivalence ratio increased. It could provide an information/insights on active control such as secondary fuel injection. Finally, local heat release rate derived from reconstructed OH images were presented for typical locations.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.269-273
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• 2011

본 논문에서는 대향류 매니폴드의 면적비에 따른 튜브형 열교환기에서의 압력강하와 유량 균일도를 분석하기위해 전산해석을 수행하였다. 유동 분배와 압력손실 특성은 입-출구 면적비에 따라 영향을 받는다. 본 연구에서, 최적의 입-출구 면적비를 선택함으로서 튜브형 열교환기의 유동 불균일도 최소와 향상된 압력손실 특성을 얻을 수 있었다.

• 터널과지하공간
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• 제14권4호
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• pp.287-294
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• 2004

지하암반 냉동저장고 주변의 온도분포를 예측하기 위하여, FLAC을 이용한 2차원 및 3차원 수치해석을 수행하였다. 수치해석 수행 시 암반 열물성에 대한 지하수 및 동결잠열의 영향을 고려하였으며, 2차원 및 3차원 수치해석 결과와 5년간의 지하암반 온도계측 자료를 비교하였다. 2차원 수치해석 결과 실험실 물성을 이용한 경우는 계측 결과와 큰 오차를 나타내었으며, 지하수 부피비 20% 및 동결잠열을 고려한 수치해석 결과가 계측 결과와 가장 작은 오차를 나타내었다. 하지만, 냉동기 가동시간이 증가하면서 지표면으로의 열 유동의 영향으로 커지는 오차는 커지는 경향을 나타내었다. 지표면의 영향을 고려하는 3차원 수치모델을 정립하여 수치해석을 수행한 결과, 지하수 및 동결잠열의 영향을 고려한 수치모델이 계측 결과가 잘 일치하는 경향을 나타내었다.