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이명성(Myungsung Lee),허남건(Nahmkeon Hur) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.6
A three-dimensional and transient propagation of wildland fire was simulated by using a physical based model. The physics based model can solve the equations governing fluid dynamics, combustion, and all modes of heat transfer such as conduction, convection, and radiation. The aim of the present study is to show a possibility of wildfire prediction on the complex large scale terrain by using the physics based model. In this study a detailed terrain on Gaya mountain was modeled including Haeinsa temple. For wildfire simulation over 65 million cells was discretized in the computational domain, and the numerical analysis was successfully performed with parallel computation. The effects of the complex terrain and weather condition like wind speed on the wildfire behavior were also investigated. The result of the present study could be applied to wildfire protection approaching cultural heritages amongst the forest.
지형에 따른 발전기 배치가 풍력 발전단지의 성능에 미치는 영향에 관한 수치해석 연구
이명성(Myungsung Lee),이승호(Seung Ho Lee),허남건(Nahmkeon Hur) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
A three-dimensional flow simulation is performed to investigate the flow field in a wind farm on complex terrain. The present paper aims to study the effects of mountainous terrain and turbine arrangement on the performance of the wind farm. A digital map of the eastern mountainous area of Korea is used to model the actual complex terrain. Wind direction and speed to be used as a boundary condition are taken from local meteorological reports. Total 49 wind turbines are modeled in the computational domain with detailed blade shape using frozen rotor method to consider rotating operation. The torque acting on the turbine blades are calculated to evaluate the performance of the wind turbines. The numerical results show details of the flow structure in the wind farm and the velocity deficit in the separated flow regions due to the topographical effect. The effect of wake induced by the upstream turbine on the performance of the wind turbine is also presented. The methodology of the present study may be used in selecting future wind farm site and wind turbine locations in the selected site for possible maximum power generation.
이명성(Myungsung Lee),원찬식(Chan-Shik Won),허남건(Nahmkeon Hur) 대한설비공학회 2008 설비공학 논문집 Vol.20 No.2
In the present study, a forest fire spread was simulated with a three-dimensional, fully-transient, physics-based, computer simulation program. Physics-based fire simulation is based on the governing equations of fluid dynamics, combustion and heat transfer. The focus of the present study is to perform parametric study to simulate fire spread through flat and inclined wildland with vegetative fuels like trees or grass. The fire simulation was performed in the range of the wind speeds and degrees of inclination. From the results, the effect of the various parameters of the forest fire on the fire spread behavior was analyzed for the future use of the simulation in the prediction of fire behavior in the complex terrain.
판형 열교환기의 Hot fluid - Plate - Cold fluid 복합 열전달 수치해석 연구
이명성(Myungsung Lee),박종택(Jongtack Park),허남건(Nahmkeon Hur),강병하(Byung Ha Kang) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
Plate heat exchanger is a device in order to exchange heat between hot and cold side. Fluid passage is formed by stacked plates which are between cold and hot fluid. The cold and hot fluid which are flowed through alternate channels in counter-current flow transfers heat through this fluid passage. Detailed design which describes complex form and all plates of heat exchanger gives us a good agreement with experiment result about flow and heat transfer characteristic but it takes much time to generate mesh and has a low efficiency of computational domain. On the other hand, simple approach method which simplies detail shape has a merit of less time to make computational domain but the reliability is decreased. In this study conjugate heat transfer is simulated in several stacked plates as cold and hot fluid passage which are generated at both sides of the middle plate and the cyclic boundary condition on outside plate of both fluid passage. The circular inlet and outlet which distribute fluid among the plates are formed in order to make computational domain considered more realistic flow. Therefore, it is easy to compare result between experimental and numerical study by increasing efficiency of computational domain as cyclic boundary condition and considering realistic flow at inlet and outlet as above. In this study steady state computation is performed in range from 0.04 ㎏/s to 0.12 ㎏/s as same mass flux in hot and cold passage, respectively. Also it is validated by experimental result having used the same type of plate heat exchanger.
이명성(Myungsung Lee),이정희(Jung Hee Lee),허남건(Nahmkeon Hur),최창근(Chang-Koon Choi) 한국전산유체공학회 2010 한국전산유체공학회 학술대회논문집 Vol.2010 No.5
A numerical wind tunnel simulation is performed in order to predict wind loads acting on a building. The aim of the present study is to suggest a guideline for the numerical wind tunnel analysis, which could provide more detail wind load distributions compared to the wind code and expensive wind tunnel experiments. To validate the present numerical simulation, wind-induced loads on a 6 m cube model is predicted. Atmospheric boundary layer is used as a inlet boundary condition. Various effect of numerical methods are investigated such as size of computational domain, grid density, turbulence model and discretization scheme. The appropriate procedure for the numerical wind tunnel analysis is suggested through the present study.