• 설비공학논문집
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• 제25권12호
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• pp.641-646
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• 2013

The purpose of this study is to improve the cooling performance of single and cascade refrigeration systems using thermoelectric modules. The system consists of a heat sink, fan, and thermoelectric module. The operating parameters considered in this study include power distribution between the first- and second-stage thermoelectric modules, air flow, and variable condensing unit. The cooling capacity increased with decreases in the temperature difference between hot and cold surfaces, but decreased with increases in the condensing temperature. The COP decreased with increasing electric power of the thermoelectric module because of the increased Joule heat. The cooling performance improvement using the thermoelectric module is represented by the freezer temperature.

• Nuclear Engineering and Technology
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• 제46권1호
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• pp.39-46
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• 2014

A total loss of all heat sinks is considered a severe accident with a low probability of occurrence. Following a total loss of all heat sinks, the degasser/condenser relief valves (DCRV) become the sole means available for the depressurization of the primary heat transport system. If a nuclear power plant has a total loss of heat sinks accident, high-temperature steam and differential pressure between the primary heat transport system (PHTS) and the steam generator (SG) secondary side can cause a SG tube creep rupture. To protect the PHTS during a total loss of all heat sinks accident, a sufficient depressurization capability of the degasser/condenser relief valve and the SG tube integrity is very important. Therefore, an accurate estimation of the discharge through these valves is necessary to assess the impact of the PHTS overprotection and the SG tube integrity of the primary circuit. This paper describes the analysis of DCRV discharge capacity and the SG tube integrity under a total loss of all heat sink using the CATHENA code. It was found that the DCRV's discharge capacity is enough to protect the overpressure in the PHTS, and the SG tube integrity is maintained in a total loss of all heat accident.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.624-629
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• 2001

An experimental study was performed to investigate adiabatic wall temperature and heat transfer coefficient around on a module with longitudinal fin heat sink cooled by forced air flow. In the first method, inlet air flow(1-7m/s) and input power(3-5W) was varied after a heated module were placed on an adiabatic floor($320{\times}550{\times}1mm^{3}$). An adiabatic wall temperature was determinated to use liquid crystal film(LCF). In the second method to determinate heat transfer coefficient, inlet air flow(1-7m/s) and the heat flux of rubber heater($0.031-0.062\;W/cm^{2}$) was varied after an adiabatic module was placed on rubber heater covering up an adiabatic floor. In addition, surface oil-film visualization were performed to characterize the macroscopic flow-field around a module.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1247-1252
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• 2004

The present paper is devoted to the modeling method based on an averaging approach for thermal analysis of microchannel heat sinks subjected to the uniform wall temperature condition. Solutions for velocity and temperature distributions are presented using the averaging approach. When the aspect ratio of the microchannel is higher than 1, these solutions accurately evaluate thermal resistances of heat sinks. Asymptotic solutions for velocity and temperature distributions at the high-aspect-ratio limit are alsopresented by using the scale analysis. Asymptotic solutions are simple, but shown to predict thermal resistances accurately when the aspect ratio is higher than 10. The effects of the aspect ratio and the porosity on the friction factor and the Nusselt number are presented. Characteristics of the thermal resistance of microchannel heat sinks are also discussed.

• Journal of Advanced Marine Engineering and Technology
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• 제34권8호
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• pp.1100-1106
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• 2010

LED는 온도가 일정이상 올라가면 효율이 떨어지고 수명이 짧아지는 단점이 있다. 본 연구는 이러한 LED의 효율적인 온도제어에 대한 것이다. LED의 방열을 위해 방열판과 팬을 사용하고 시스템의 온도제어는 원칩 마이크로프로세서와 PID제어를 통해 원하는 온도를 제어할 수 있음을 실험을 통해 확인한다. 궁극적으로 팬을 냉각장치로 사용하고 이를 잘 제어하면 LED 시스템 구동전력의 약 2%만을 사용하여 적절한 조도와 온도를 유지하는 성능을 얻을 수 있음을 제어실험을 통해 확인하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.717-718
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• 2011

• 전력전자학회논문지
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• 제6권6호
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• pp.572-581
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• 2001

최대 1800W의 열부하를 발생하는 전력반도체를 냉각하는 히트파이프 히트싱크를 설계하고 제작하였다. 히으파이프 냉각장치는 4개의 외경 22.23mm 인 FC-72 히트파이프, 알루미늄 블록 (130${\times}$160${\times}$35mm) 및 126개의 알루미늄핀 (250${\times}$58${\times}$0.8mm)으로 구성되어 있다. 성능 실험결과 총열저항은 1~2kW의 열부하일때 2~3m/s의 풍속에 풍속의 증가에 따라 0.02~0.018$^{\circ}C$/W 를 나타냈다. 이 결과는 3 m/s의 풍속에서 1800W의 열부하가 주어질 때 $40^{\circ}C$미만의 온도상승을 나타내는 것으로 설계 목표를 잘 만족하였다. 이 외로 대류 및 히트파이프의 열저항의 실험값은 몇가지 상관식에 의한 예측값과 비교적 잘 일치하였다.

• 한국전자통신학회논문지
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• 제15권2호
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• pp.313-318
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• 2020

300도 이상의 높은 용융점을 갖는 소위 엔지니어링 플라스틱은 기구적인 강성과 내화학성 및 마찰 및 마모성능이 우수하여 여러 산업에서 금속을 대체하는 소재로 각광받고 있다. 본 연구에서는 용융적층모델링 공법을 기반으로 하는 3D 프린터에서 높은 용융점을 갖는 엔지니어링 플라스틱을 조형할 수 있도록 방열특성이 우수한 3D 프린터 nozzle부의 구조를 설계하고 이를 해석적으로 검증하였다. 높은 온도로 가열되는 heat block과 필라멘트가 이송되는 nozzle상부 간의 단열 및 신속한 냉각을 위하여, 열전도계수가 낮은 열차단부(heat brake부)를 2중으로 구성하였고, 열차단부에 생성되는 열이 냉각핀을 통해 대기에 의해 냉각되는 구조를 적용하였다. 개선된 nozzle부 구조설계를 통해 종래 3D 프린터의 BCnozzle과 비교할 때, heat sink부에서의 온도를 50% 가량 낮출 수 있었으며, heat block에 직접적으로 연결된 heat brake부 최종단의 정상상태 온도를 14% 가량 낮출 수 있었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.143.2-143.2
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• 2011

Energy foundations and other thermo-active ground structure, energy wells, energy slab, and pavement heating and cooling represent an innovative technology that contributes to environmental protection and provides substantial long-term cost savings and minimized maintenance. This paper focuses on earth-contact concrete elements that are already required for structural reasons, but which simultaneously work as heat exchangers. Pipes, energy slabs, filled with a heat carrier fluid are installed under conventional structural elements, forming the primary circuit of a geothermal energy system. The natural ground temperature is used as a heat source in winter and heat sink in summer season. The system represented very high heating and cooling performance due to the stability of EWT from energy slab. Maximum heat pump unit COP and system COP were 4.9 and 4.3.

• Computers and Concrete
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• 제30권1호
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• pp.1-8
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• 2022

The basic purpose of the current study is to compute the numerical analysis of heat source/sink for Darcy-Forchheimer three dimensional nanofluid flow with gyrotactic microorganism by rotatable disk via porous media under the slip conditions. Due to nanoparticles, random and thermophoretic motion phenomenon occurs. The governing mathematical model is handled numerically by shooting method. Additionally, the characteristics of velocities, mass, heat, motile microorganisms and associated parameters are thoroughly analyzed via plots and tables. Different physical parameters like Forchheimer number, slip parameters like velocity, porosity parameter, Prandtl number, Brownian number, thermophoresis parameter, heat sink/source parameter, bioconvected Rayleigh number, buoyancy parameteron dimensionless velocities, temperature. Approximate values of Sherwood microorganism are analyzed.