• 조명전기설비학회논문지
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• 제19권6호
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• pp.29-35
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• 2005

본 논문은 고온 초전도 케이블을 전력계통의 송전용량 증대를 위해 적용시켰을 경우, 고장발생시 초전도케이블에서 예상되는 ??????치의 영향에 대해 안전하게 제어할 수 있는 방법을 제시하였다. 접근 방법으로는 초전도케이블의 ??????치 특성을 열평형 방정식으로 모델링하고 그 결과 고장전류에 따른 케이블의 설계 최대 온도상승한계에 도달하는 시간을 산출하여 기존의 보호계전시스템의 차단시간과 비교함으로서 안전성 여부를 판정하였다. ??????치발생 고장시간을 모의하기 위해 초전도케이블용 EMTDC모형을 개발하였으며, 모의 결과 초전도 케이블 계통을 보호할 수 있는 안전성 제어방식이 설계 가능함을 보였다.

• International Journal of Air-Conditioning and Refrigeration
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• 제14권3호
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• pp.110-117
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• 2006

Ice adhesion or cohesion leads to the decrease of the performance of ice making system, especially to dynamic type ice thermal storage system (DISS) which mainly forms ice from the flow of an aqueous solution. The ice adhesion is influenced by various parameters associated with operating or geometric condition. In this study, the influence on an adhesion of ice to the characteristic of cooling surface and to composition of an aqueous solution was fundamentally observed by using batch type cooling device,. a beaker. Three patterns of solution in each beaker were cooled with brine. Moreover, the characteristic of cooling surface on each beaker was distinguished to coating materials. Stirring power as a degree of the ice adhesion was measured. The stirring power to cooling heat transfer rate in each beaker was compared. As a result, the lowest stirring power of 8.9 W with non-adhesion of ice, was shown in the case of the aqueous solution of EG(4) + PG(1.5) + 1,6HD(1.5). in PE coating beaker.

• Journal of Advanced Marine Engineering and Technology
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• 제29권1호
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• pp.42-48
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• 2005

Because Impinging jet has excellent heat & mass transfer characteristics. it has many advantages of cooling. drying. etc and widely applied at industrial fields. Therefore, there have been many experimental investigations and theoretical studies about Impinging jet. The present study is about a cooling characteristic by Impinging jet for a Square Plate on Duct and investigated this characteristic through three-dimensions numerical analysis, using FLUENT. As the result of this study, heat transfer effect is the most appropriate condition when the ratio of distance is 6 between nozzle exit diameter and heat source. diameter of duct is 90mm and height of duct is 60mm. In addition. under the influence of injected jet. stagnant fluid flow into free jet field and this affected the whole flow field. So the shape of duct is a important factor and the researcher confirmed the need of investigation about duct.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.16.1-16.1
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• 2005

• Elastomers and Composites
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• 제38권3호
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• pp.206-212
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• 2003

본 논문에서는 인솔에 coolant가 있는 골프화에 대해서 이론적인 해석방법과 설계기술을 연구하였다. 골프화를 구성하고 있는 인솔의 형상과 미드솔, 아웃솔을 고려하여 유한요소법으로 모델링하였다. 열전달을 위한 유한요소의 경계조건으로는 인간발의 표준적인 온도가 사용되었다. 열전달해석을 위해 상용프로그램으로는 MARC V7.3를 사용하였고 온도 및 인솔의 열전도량을 구했다. 본 연구에서 열전달의 특성에 따라서 유한요소법의 결과가 다르게 나온다는 결론을 얻었다. 본 연구 결과는 골프화 해석에 보다 나은 이해를 제공해준다. 더욱이, 본 연구결과는 골프화 관련 업체에서 활용할 경우 보다 효과적으로 설계하도록 도울 것이라고 믿는다.

• 한국항공우주학회지
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• 제35권10호
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• pp.927-933
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• 2007

초음속 유동장 내에 돌출된 핀에 의해 발생하는 바닥면의 열전달 특성 변화 연구를 수행하였다. 마하수가 3이고, 레이놀즈수가 $5{\times}10^7$인 초음속 유동내에 받음각이 $12.5^{\circ}$부터 $20^{\circ}$인 기울어지지 않은 형태의 선단이 날카로운 핀(sharp fin)을 돌출시켜 충격파를 발생시켰다. 이로 인해 생기는 바닥면의 열전달 계수의 변화를 적외선 카메라를 이용한 온도 분포의 측정을 이용하여 계산하였다. 또한 바닥면 유동의 흐름을 파악하기 위해 수치해석과 유막법이 수행되었다.

• Journal of Advanced Marine Engineering and Technology
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• 제39권7호
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• pp.696-701
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• 2015

본 연구에서는 깊이 0.2 mm, 폭 0.45 mm, 길이 60mm 그리고 채널의 개수는 15개인 마이크로 채널에서 이상 유동비등에 관한 실험을 수행하였다. 작동유체로는 FC-72가 사용되었으며, 실험은 질량유속과 열유속 각각 $200-400kg/m^2s$, $5-40kW/m^2$ 범위와 증기 건도 0.1-0.9 범위에서 수행되었다. 열전달 계수는 낮은 열유속에서는 급격하게 감소하였으며, 일정 열유속 이상에서는 거의 일정하게 유지되었다. 측정된 열전달 계수로부터 기존의 방법을 이용하여 기포류, 슬러그류, 천류 그리고 파형/환상류의 유동양식으로 분류하였다. 또한 분류한 유동양식의 결과를 파형/환상류 영역으로의 천이 기준과 비교하였다. 하지만 기존의 천이 기준으로는 본 연구의 실험결과를 만족스럽게 예측하지 못하였다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 추계학술발표대회 논문집
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• pp.32-37
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• 2009

An energy loss through the window system occupies about 10 to 30 percent on energy consumption of the whole building. That is the reason, several elements for a building composition of window system are the weakest from the heat. Insulation performance increases for the reducing heat loss. Heat transfer through the window system that is reducing heat transfer through conduction, convection and radiation. Insulation performance reinforcement methods classify improving heat specific quality of window system and improving efficiency of whole window system. The most application method among each methods is reducing emission ratio of the window system(Low-E glass), increasing a number of glazing(multiple window) and a method of vacuuming between glazing and glazing. Therefore this study is investigated a sort of glazing and specific character, U-value calculation with changing glazing thickness and calculation of temperature distribution and U-value with a glazing charging gas kind from double glazing. For a conclusion, an aspect of U-value figure at the smallest value case of vacuum glazing with Low-E coating. That means insulation efficiency is the best advantage during a building plan selecting vacuum glazing with Low-E coating for a energy saving aspect. In this way, U-value become different the number of glazing, coating whether or not and selecting injection gas. Therefore selecting of glazing is very important after due consideration by a characteristic and use of building and consideration of strong point and weak point.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.385-391
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• 2000

An analysis of the heat transfer in a PDP ventilation chamber has been conducted to investigate the required heat curve and temperature uniformity of the panels. Firstly, experiment in a test chamber has been carried out and compared with the unsteady 3D numerical simulation. Reasonable agreement was found, which suggested that the employed numerical model had its credibility in an actual PDP ventilation process. On this ground, tact-type heating/cooling system was analyzed. The panel temperature was more uniform in the $40^{\circ}C$ tact-type system than in the $80^{\circ}C$ one. Comparison of full simulation of a cart and simplified simulation of one panel shows the panel pitch, which is closely related to a production rate, can be also predicted.

• 한국표면공학회지
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• 제52권3호
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• pp.171-179
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• 2019

We have developed a numerical model to analyze flow dynamics and heat transfer characteristics of the cooling water in a circular rotating magnetron cathode by a moving boundary grid method realized in a commercial multiphysics package, CFD-ACE+. The numerical model is composed of a target, dual mass rotating cathode and cooling water connections. When the inlet and outlet of the cooling water are offset by the same distance from the rotation axis, the temperature at the center is higher by $50^{\circ}C$ at maximum. At 5 mm away from the target surface, the temperature profile showed typical center high characteristic. At heat input of 30 kW, the maximum temperature change of the cooling water hits $6^{\circ}C$ within 0.5 sec under 60 rpm. With a cooling water configuration of center in/edge out, the temperature of the center region of the target gets lowered. Within 100 seconds of plasma operation time, the cooling water temperature keeps getting higher.