• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.05a
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• pp.15-20
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• 1998

전산유체역학 기법을 이용하여 석탄가스화기 내화재내에서의 온도분포 해석 및 열손실량 계산을 수행하였다. 일차원 이론적 해석, 이차원 전도열전달 해석 및 삼차원 대류-전도 복합열전달 해석 등 세 가지 방법론으로 전산해석을 수행하고 그 결과들을 서로 비교하였으며, 또한 해석결과들을 석탄가스화기 실험결과와 비교하였다. 결과의 정확성, 수치해석상의 편리성(수렴성 및 계산시간) 등을 종합적으로 검토하여, 이차원 전도열전달 해석이 공학적 설계에 적용하기 적절한 방법론임을 제시하였다. 전산해석 결과를 3톤/일급 석탄가스화기에 적용해 본 결과, 총 열손실량은 설계치 운전기준으로 약 1% 정도인 것으로 판별되었다.

• Journal of Energy Engineering
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• v.8 no.1
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• pp.67-75
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• 1999

여러 종류의 내화재로 구성된 석탄가스화기에서의 온도분포 및 열손실량을 구하기 위한 전산해석을 수행하였다. 석탄가스화기 내화재 설계를 위한 적절한 방법론을 제안하기 위하여 1차원 이론적 해석, 2차원 전도열전달 해석 및 3차원 대류-전도 복합열전달 해석 등 세가지 방법론으로 해석을 각각 수행하였다. 해석 결과들은 석탄가스화기 실험 결과와 정상적 정량적으로 잘 일치하는 것으로 나타났다. 결과의 정확성, 수치해석 상의 수렴성 및 계산시간 등을 종합적으로 고려해 볼 때, 전산해석에 핵심 경계조건인 가스화기 내벽의 온도를 적절히 설정할 수 있는 경우에는 2차원 전도열전달 해석이 공학적 설계에 적용하기 알맞은 방법론으로 판단되었다. 전산해석 결과에 의하면, 현재 실험이 진행중인 하루 3톤 처리 용량급의 석탄가스화기에서의 총 열손실량은 설계치 운전 기준으로 약 1% 정도인 것으로 판별되었다.

• Journal of the korean Society of Automotive Engineers
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• v.11 no.1
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• pp.20-30
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• 1989

The unsteady conjugate forced convection-conduction heat transfer from a plate fin is numerically studied. The external forced flow is steady but the temperature of the fin base is an exponential change with time. Therefore, the unsteady energy equations of the fluid and the fin are solved simultaneously under the conditions of equality in heat flux and temperature at the fluid-fin interface at every instant of time. Numerical results are given for various quantities of interest including the local heat transfer coefficient, the local heat flux, the total heat transfer rate and the temperature distribution of fin under the effects of the convection-conduction parameter and the ratio of thermal diffusivities. The results of the present numerical solution have been compared with those of the conventional fin theory.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.5 no.4
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• pp.265-277
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• 1993

Recently, underground transmission system is growing continuously according to the electric power demand increase in the downtown area. Even if domestic cable makers are manufacturing 154kV oil filled cable and joint, the design technology of cable-joint has not been fully self-reliance. This study is aimed at the detail heat transfer analysis of 154kV cable-joint. So, that is cut into the five sections in order to analyze a conjugate natural convection in two dimensional $r-{\theta}$ coordinate. The streamline and temperature distributions are obtained for each sections. Also the changes of those are analyzed with respect to the variation of transmission currents and cable-joint surface heat transfer coefficients. The same analyses are also shown in view point of the maximum temperature of conductor and local equivalent conductivity.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.5
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• pp.655-662
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• 1985

화염스트레치와 확산선호도가 예혼합화염에 미치는 영향을 몇가지 모델에 대해 현상적으로 고 찰하였다. 즉, 정상상태의 구형화염, 구형으로 전파되는 화염, 균일유동장내의 곡면화염, 일차원 평면화염, 그리고 확대유동장내에서 스트레치된 평면화염등을 고찰하였으며, 이 해석의 결과는 화염면의 면적 변화율로 정의된 화염스트레치의 제인자들 즉, 비균일 접선속도장과 전파화염의 곡률에 의한 영향들이 공통적 특성을 나타냄을 보여주고 있다. 화염스트레치와 확산선호도가 화염전파속도에 미치는 복합효과는 세가지로 나타나는데 이는 화염온도의 변화에 따른 화학반 응강도의 변동, 열 및 물질확산의 강도차이, 그리고 대류 및 확산전달의 방향의 상이함에 기인 한다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.6
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• pp.512-518
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• 2002

The real chip and similarity model were used to investigate the thermal behavior and velocity distribution of air from the heat source with the location and the amount of heat experimentally and numerically, and compared. The heat generated in the block is not cooled by convection and show the high temperature by the stagnation of heat flow. After maintaining the high temperature of block by the natural convection, the sudden drop of temperature with the air flow was shown in the channel but the decreasing rate was small with the time. The inward block was effected by infinitesimal air flow generated between block and channel and outward block was effected by the entry condition.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2013.11a
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• pp.57-58
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• 2013

소방보호복은 고열유속에 의한 화상방지를 위해 3층 이상의 복합소재로 구성되어 있으며, 각 소재 사이는 공기 간극이 존재한다. 화재에 의한 고열유속 노출 시 공기 간극 내에서의 열전달은 대류와 복사에 의해 주로 발생하며, 그로 인해 간극의 크기에 따라서 비선형 특징의 열 저항 크기를 갖게 된다. 그러므로 본 연구에서는 보호복 소재 사이의 여러 가지 공기 간극에 대한 보호복의 열 보호성능을 자세히 파악하기 위한 실험을 수행하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.2
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• pp.119-124
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• 2015

Numerical study on the new design of the liquid mass flow meter in infinitesimal flow rate for semiconductor production is performed. The heater and thermistor are wired on the circular tube about 0.3mm inner diameter with designed gap between them. After the time interval from the single pulse heating the thermistor reaches its peak temperature and this time interval is almost inversely proportional to the liquid mass flow rate. The axial conduction in tube wall and convection through the flow is combined. As a result, the peak temperature moving velocity is much smaller than flow mean velocity and there is no linear relationship between them. In this study, the effects of design parameters such as the tube inner/outer diameter, wired heater width, and the gap between heater and thermistor are investigated and the trends of optimization in these parameters are discussed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.2
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• pp.453-462
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• 1990

The interaction of forced convection-conduction with thermal radiation in laminar boundary layer over a plate fin is studied numerically. The analysis is based on complete solution whereby the heat conduction equation for the fin is solved simultaneously with the conservation equations for mass, momentum and energy in the fluid boundary layer adjacent to the fin. The fluid is a gray medium and diffusion(Rosseland) approximation is used to describe the radiative heat flux in the energy equation. The resulting boundary value problem are convection-conduction parameter N$_{c}$ and radiation-conduction parameter m, Prandtl number Pr. Numerical results are presented for gases with the Prandtl numbers of 0.7 & 5 with values of N$_{c}$ and M ranging from 0 to 10 respectively. The object of this study is to provide the first results on forced convection-radiation interaction in boundary layer flow over a semi-infinite flay plate which can be used for comparisons with future studies that will consider a more accurate expression for the radiative heat flux. The agreement of the results from the complete solution presented by E. M. Sparrow and those from this paper for the special case of M=0 is good. The overall rate of heat transfer from the fin considering radiative effect is higher than that from the fin neglecting radiative effect. The local heat transfer coefficient with radiative effect is higher than that without radiative effect. In the direction from tip to base, those coefficients decrease at first, attain minimum, and then increase. The larger values of N$_{c}$ M, Pr give rise to larger fin temperature variations and the fin temperature without radiative effect is always higher than that with radiative effect.

• Journal of the Korean Institute of Gas
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• v.5 no.3 s.15
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• pp.1-8
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• 2001

This study was carried out for the purpose of determination of maintenance period and investigation of weak point due to freeze when the gas heater of KOGAS valve station Is not operated in winter season. 3-dimensional non-linear numerical simulation was conducted in order to predict the time and location which bath water in heater reaches to ice point. FLUENT V 5.0, commercial code, is used for thermal fluid flow analysis. We thought this was problem of heat conduction solving the energy equation and modeled gas heater by using the real geometry and scale for performing the 3-dimensional simulation. It was analyzed complex heat transfer phenomena considering convection due to air on surface, conduction in insulation material, natural convection of liquid in heater and heat loss through the pipe.