• 비료회보
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• s.328
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• pp.43-46
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• 1987

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.459-466
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• 2005

The present study investigates the heat transfer characteristics of a triangular channel. Three different rib configurations are tested. The ribs are installed on two sides of the channel. The rib height (e) to channel hydraulic diameter is 0.079 and the rib-to-rib pitch (p) is 8 times of the rib height. The rotation number ranges from 0.0 to 0.1 while the Reynolds number is fixed at 10,000. The copper blocks with heaters are installed on the channel walls to measure the regionally averaged heat transfer coefficients. For the stationary $45^{\circ}$ and $135^{\circ}$ ribbed channels, a pair of counter rotating vortices is induced by the angled rib arrangements, and high heat transfer coefficients are obtained on the regions near the inner wall for the $45^{\circ}$ ribbed channel and near the leading edge for the $90^{\circ}$ ribbed channel. The heat transfer coefficients of angled ribbed channels are changed little with rotation, whereas those of the transverse ribbed channel are changed significantly with rotation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.7
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• pp.703-714
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• 2010

This paper describes the design optimization of a rotating rectangular channel with staggered arrays of pin-fins by Kriging metamodeling technique. Two non-dimensional variables, the ratio of the height to the diameter of the pin-fins and the ratio of the spacing between the pin-fins to the diameter of the pin-fins are chosen as the design variables. The objective function that is a linear combination of heat transfer and friction loss related terms with a weighting factor is selected for the optimization. To construct the Kriging model, objective function values at 20 training points generated by Latin hypercube sampling are evaluated by a three-dimensional Reynolds-averaged Navier-Stokes (RANS) analysis method with the SST turbulence model. The Kriging model predicts the objective function value that agrees well with the value calculated by the RANS analysis at the optimum point. The objective function is reduced by 11% by the optimization of the channel.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.274-277
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• 2012

Large eddy simulation is applied to the turbulent flow and heat transfer in straight cooling passages with varying aspect ratio. The turbulent statistics of the flow and thermal quantities are calculated and the characteristics of Nusselt number are investigated. To scrutinize near-wall streamwise vortices, a conditional sampling technique is adopted. Clockwise and counter-clockwise rotating streamwise vortices are sampled and the probability density function of the vortex circulation Reynolds number and wall Nusselt number are calculated.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.343-344
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• 2010

화석연료의 고갈로 인하여 친환경 자동차에 대한 연구와 상용화가 급속도로 진행되면서 점점 대형 차종으로 그 범위가 넓어지고 있다. 대형 차종에 적용되는 전기동력 시스템의 MCU(Motor Control Unit), GCU(Generator Control Unit), DC/DC 컨버터 등과 같은 전장품도 그 용량이 커지면서 상용화를 위해 효율적인 측면도 많이 부각되지만 스위칭 소자, 변압기, 초크, 다이오드 등에서 동작으로 인해 열이 발생하고 제품의 구조상 밀폐된 공간에 장착이 되기 때문에 발열로 인한 동작의 신뢰성과 제품의 내구성에 큰 영향을 미치게 된다. 그중 가장 발열이 심한 IGBT(Insulated Gate Bipolar Transistor) 등과 같은 스위칭 소자에서 발생하는 열을 효과적으로 냉각시키기 위해 수냉구조가 필수적이며 동일한 조건의 수압, 유량에 보다 높은 방열특성을 가지기 위해 냉각구조에 대한 해석이 제품을 개발 전에 선행되어야 한다. 본 논문에서는 유로의 냉각핀 형상과 유로 구조에 따라 방열특성이 어떠한 차이가 있는지 시뮬레이션 프로그램을 통하여 비교하고, 모사발열체를 이용한 방열부의 냉각 성능 시험과 다이나모 환경의 최대 출력 시험을 통하여 방열 특성을 확인하였다.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.81-82
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• 2008

고온초전도 케이블은 초전도 상태를 유지하기 위해서 반드시 액체질소를 이용한 냉각시스템이 필요하다. 액체질소는 순환펌프에 의해 케이블의 유로를 순환하고 케이블을 냉각시키게 된다. 논문에서는 초전도 케이블의 냉각시스템의 기돈 설계에 있어서 중요한 운전온도 운전압력, 열부하에 대해서 고찰하였고, 현재 국내 초전도 케이블의 연구개발에 대해 고찰함으로써 향후 초전도 케이블이 실용화되기 위해 나아가야 할 방향에 대해 제시하였다.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2008.11a
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• pp.350-351
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• 2008

• Proceedings of the Optical Society of Korea Conference
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• 2009.10a
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• pp.68-69
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• 2009

• Nuclear Engineering and Technology
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• v.21 no.4
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• pp.259-266
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• 1989

An improved version of RELAP5/MOD2 Cycle 36.04 code is assessed for LOFI LBLOCA Test L2-5. Minor modifications to the original version have been done to avoic reflood related errors. Based on the modified version, one base case and two cases for sensitivity study on downcomer and core channel modelling are calculated. The calculation results are compared with the experimental data for primary system pressure, break mass How rate and cladding temperature at hot spot According to the comparison, it is found that the hydraulic system behaviors are well predicted, excessive core cooling exist in blowdown phase for a single core channel and a combined downcomer case, and a better result can be obtained for a two core channel case.

• Proceedings of the Korean Nuclear Society Conference
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• 1999.05a
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• pp.136-136
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• 1999