• Tunnel and Underground Space
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• v.14 no.1
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• pp.16-25
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• 2004

As underground caverns have many advantages such as safety and operation, they can also be used for gas storage purpose. When liquefied gas is stored underground, the cryogenic temperature of the gas affects the stability of the storage cavern. In order to store the liquefied gas successfully, it is essential to estimate the exact temperature distribution of the rock mass around the caverns. The main purpose of this study is the development of theoretical solution to be able to estimate the temperature distribution around storage caverns and the assessment of the solution. In this study, a theoretical solution and a conceptual model for estimating two and three dimensional temperature distribution around the storage caverns are suggested. Based on the multi-dimensional transient heat transfer theory, the theoretical solution is successfully derived by assuming the caverns shape as simplified geometry. In order to assess the theoretical solution, by performing numerical experiments with this multi-dimensional model, the temperature distribution of the theoretical solution is compared with that of numerical analysis. Furthermore, the effects of the caverns size are investigated.

• Publications of The Korean Astronomical Society
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• v.6 no.1
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• pp.16-26
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• 1991

스펙트럼선의 선폭증대 현상을 방출영역 내 기체입자들이 열운동에 의한 단순 도플러 효과로 가정하여 중심에서 어느 한쪽으로 심하게 치우친 스펙트럼 선윤곽를 해석한다. 본 연구에서는 태양활동영역에서 흔히 관측되는 좌우 비대칭의 선윤곽을 서로 다른 가우스속도분포의 기체성분들이 시선방향으로 중첩된 결과라 해석하고, 최소자승법을 이용한 비선형 선윤곽 맞춤질에 의해 스펙트럼 방출영역에서 떨어져 나가는 기채들의 온도 및 분출속도에 관련된 도플러선폭과 도플러이동량을 구하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.633-638
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• 1997

중소형 일체형 원자로의 자연대류 실험 및 해석을 통해 일체형 원자로의 자연대류에 의한 잔열제거 기능의 특성 및 피동 안전성을 파악하였다. 이를 위해 일체형 원자로 축소 실험장치를 이용한 자연대류 실증 실험을 수행하였으며, 실험 결과를 RETRAN-03와 COMMIX-1B 코드 해석 결과와 비교, 검증하였다. 실험 결과 일부 증기발생기의 열제거 기능 상실이 발생한 경우에도 노심으로 유입되는 냉각재의 온도가 균일하게 분포하여 피동 잔열 제거가 원만히 일어남을 알 수 있었고 해석 결과와 일치하였다.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.2
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• pp.99-112
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• 2015

In this study, laboratory test equipment was designed and installed to evaluate the thermal behavior of bentonite, which is used as a buffer in high-level waste disposal systems. The thermal analysis was conducted to verify the test results using ABAQUS, a finite element analysis code. In view of the seasonal changes seen during the test, the thermal behavior of bentonite with a temperature of outside air was evaluated. Of the cases examined, the results of the analysis model using stainless steel (Case 3) approximates to the test results, showing an error of about 1℃. The results of the thermal analysis into seasonal temperature distributions are consistent with trends seen in lab-test results. These analyses show that the effects of the thermal conductivity of the material surrounding the buffer and outside air temperature, are very important factors in the thermal behavior of bentonite. In the future, it is expected that a moisture saturation test of a bentonite buffer containing a heat source will be carried out. Therefore, the development of a numerical analysis model is required for the prediction and verification of the laboratory test results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.12
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• pp.801-807
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• 2016

This paper aims to compare and study the cooling performance of a battery system in accordance with the inlet and outlet geometry of the air passage in an EV. The arrangement and the heat source of the battery module were fixed, and the inlet/outlet area and its geometry were varied with the analysis of the cooling performance. The results of this study provide suggestions for the air flow stream line inside of a battery, the velocity field, and the temperature distributions. It was confirmed that the volume flow rate of air should be over $400m^3/h$, in order to satisfy conditions under $50^{\circ}C$, which is the limit condition for stable operation. It was also revealed that the diffuser outlet geometry can improve the cooling performance of battery system.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.6
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• pp.19-25
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• 2015

Numerical simulations of the hot gas valve with a pintle have been conducted in order to investigate the effect of numerical methods and computational domains. The grid sensitivity is checked by varying the grid number from 100,000 to 1,700,000. The existence of ambient region doesn't make the significant differences of the flow-field and the temperature distribution. Three turbulence models are adopted to figure out its influence on the thrust and temperature distribution: Spallart-Allmaras, RNG $k-{\varepsilon}$, $k-{\omega}$ SST. The thrusts of the hot gas valve are almost same in all cases of the simulation, however, there are about 5% difference in the temperature distribution. With the ambient region, the difference are observed in the temperature distribution with respect to the number of grids.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.284-289
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• 2019

The Korea Foldable safe pathway system is an evacuation support system to get temporary evacuation route in railway tunnel and large space fires. A prevention smoke screen is unfolded in fires and it is needed to prevent heat and smoke from fire source. Therefore, ventilation system for positive pressure condition is equipped with foldable safe pathway system. Numerical analyses of temperature and pressure distribution with distance from fire source were performed considering fire scenario of new train vehicle. The smoke temperatures did not exceed $200^{\circ}C$ that distance from the fire source was more than 20 m and smoke pressure was reduced with distance from fire source. Maximum smoke pressure was 14 Pa and average pressure was 6 Pa in position of prevention smoke screen. As results, to install foldable safe pathway system, ventilation system is need to maintain 6 Pa positive pressure condition.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.4
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• pp.338-344
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• 2018

The lunar surface temperature is important as a environmental parameter for the thermal design of the lunar exploration vehicles such as orbital spacecraft, lander, and rovers. In this study, the temperature is numerically predicted through a simplified lumped system model for the energy conservation. The physical values required for the analysis of the energy equation are derived by considering the geometric shape, and the values presented in the previous research results. The areal specific heat, which is the most important thermo-physical property of the lumped system model, was extracted from the temperature measurements by the Diviner loaded on the LRO, and the value was predicted by calibration of the analytical model to the measurements. The predicted temperature distribution obtained through numerical integration has sufficient accuracy to be applied to the thermal design of the lunar exploration vehicles.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.857-863
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• 1998

배관내에서 서로 다른 온도의 유체가 밀도차에 의해서 층이 분리된 채 존재하는 현상을 열성층 (thermal stratification) 현상이라 부르며, 이 현상에 의한 과도한 열응력은 배관의 건전성을 저해할 수 있다. 국내 원전의 경우 영광 3,4호기 이전의 밀림배관에서는 열성층 영향을 고려치 못하여 이에 대한 건전성 평가가 요구되고 있다. 본 연구에서는 고리 4호기 가압기 밀림배관을 대상으로 밀림배관내 유동해석 및 발전소 전 운전조건에 대하여 밀림배관 단면 온도분포 실측실험을 통하여 열성층화 현상의 발생 정도를 확인 하였으며 실측 온도 데이터를 이용하여 열응력해석 등을 수행함으로써 밀림배관의 열성층 영향을 평가한 결과 건전함이 확인되었다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.55-55
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• 2014

도전체에 적절한 열을 가하기 위하여 상당히 높은 수준의 자기장을 이용한다. 이러한 높은 자기장을 만들기 위하여 유도가열 코일은 상당히 높은 고주파 전류를 이용하게 되는데, 이로 인하여 코일 자체에도 상당히 높은 발열이 발생하게 된다. 따라서 실제적으로 코팅물질의 발열을 위하여 전달되는 에너지 이외에 소모적으로 사용되는 코일에서 사용되는 에너지가 어쩔수 없이 존재하게 된다. 이는 전자기코일의 효율을 낮추는 역할 뿐만 아니라 안정적인 운전을 저해하는 역할을 하게 된다. 본 논문에서는 전자기 및 온도 해석을 통하여 유도가열 코일의 구조에 따른 효율 및 코일에서의 온도 분포등을 도출하여 전자기 유도가열코일의 설계에 이용하고자 한다.