• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• 제13권6호
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• pp.448-454
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• 2001

In the present study, the transient axi-symmetric numerical simulation of traffic ventilation induced by a train running through a 15.6km-long tunnel is performed by using over 100,000 computational cells. With train running, three cases of ventilation schemes are simulated, which are the case of ventilation fans turned on, the case of no fan but ventilation shafts open, and the case of no fan and no shaft. Results of the ventilation flow rate are pressure transients are compared for the cases considered.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• 제13권3호
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• pp.217-223
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• 2001

There exist a number of approaches which can evaluate ventilation and indoor air quality. The measurement and analysis of indoor carbon dioxide concentrations can be useful for evaluating indoor air quality and ventilation. This paper describes a numerical analysis of carbon dioxide concentrations for evaluating indoor air quality and ventilation and the factors the need to be considered in their use. The conditions of this numerical analysis are tow types of positions and inlet velocities of ventilation system in a two-dimensional model of an apartment house. The simulation results could be used as a base data for further analysis for ventilation design of other industrial processes producing a proper ventilation system for a healthier and more comfortable environment in a building.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.10-13
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• 2010

The flow field in road tunnel is influenced by some facts such as piston effect of vehicle's move, operation of ventilation facilities, natural wind and buoyancy effect of fire plume. Among those, jet fan is one of main ventilation facilities especially in longitudinal ventilation system of tunnel. In this study to analyze tunnel flow induced by operation of jet fan, numerical simulation has been carried out. The velocity distributions and streamlines in tunnel are examined to consider the three-dimensional characteristics of tunnel flow caused by jet fan.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• 제12권10호
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• pp.908-916
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• 2000

In this paper, the characteristics of moisture ventilation in the lithium ion battery manufacturing dry room are studied numerically using standard $k-\varepsilon$ turbulence model. Both the steady-state and the unsteady behaviors of moisture ventilation are analyzed by considering local and uniform moisture generation. In order to evaluate the characteristics of moisture ventilation, three scales of ventilation efficiency and characteristic ventilation time are presented from the numerical results. It was shown that moisture distribution was dependent strongly on the flow field. The characteristics of moisture ventilation were improved by 20% and 40% in terms of the 1st scale of ventilation efficiency (SVE1) and the 2nd scale of ventilation efficiency (SVE2), respectively, through the modifications of design variables such as the addition of inlets, outlets and partition. A significant improvement in the characteristic ventilation time and the moisture exhaust efficiency was also made by these modifications.

• International Journal of Air-Conditioning and Refrigeration
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• 제17권2호
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• pp.45-51
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• 2009

Three-dimensional numerical analyses of mechanical ventilation system in vent shaft of subway in operation are carried out in relation with the different air flow passage of vent shaft and two ventilation operation modes of push/pull, The ventilation characteristics of vent shaft with regard to the shape change are evaluated. And the air flow rate through the vent shaft by ventilation system is measured within subway in operation to assess the accuracy and applicability of the numerical analysis method. The decrease of air flow rate due to vent-shaft change are between 0.7 to 2.2% in the cases examined.

• Tunnel and Underground Space
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• 제8권1호
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• pp.8-16
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• 1998

The first purpose of this study is to verify the application of computer modelling to a enclosed space fire. The second one is to determine temperature distribution for the three different ventilation types in case of a enclosed space fire. The third one is to find out the ventilation direction and ventilation quantity to remove effectively heat and combustion products generated by a fire in variable air volume(VAV) system. Firstly, compared with experimental results of Lawrence Livermore National Laboratory(LLNL), numerical results show good agreements. Secondly, among three different ventilation types, the numerical analyses show the highest temperature distribution in occupied zone(up to 1.8 m from bottom) from firing moment to 100 sec. when supply ducts are placed in ceiling and extract duct is placed close to the bottom on side walls. This is due to disadvantageous position of extract duct in ventilating high temperature air which rise because of buoyancy force. Thirdly, this study finds out effective ventilation direction and ventilation quantity to remove heat and combustion products generated by a fire by using VAV system. $CO_2$ concentration is used as a fire fume removal index. As soon as a fire happens, ventilation direction is changed in order to gather and drive out fire fumes. In case of three times ventilation quantity of ordinary one, $CO_2$ concentration and temperature have begun to decrease at 120 sec. after firing, i.e.fire fumes have begun to be removed.

• Journal of the Korean Solar Energy Society
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• 제30권2호
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• pp.87-95
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• 2010

This study analyzed the performance of solar chimney system for natural ventilation in underground space. A mathematical model of the solar chimney was proposed in order to predict its performance under varying parameters and Korea climatic condition. Steady state heat transfer equations were set up using a energy balanced equations and solved using a inverse matrix method. Numerical simulation program to analyze system was developed by using MATLAB. As the results, the ventilation performance of the solar chimney was determined by the temperature difference of air channel and inlet, and the temperature difference was influenced by insolation, stack height and distance of air gab. Also the solar chimney system can provide $262.9m^3/h$ of annual average ventilation rate. Because seasonal differences of ventilation rate was calculated within 25%, the solar chimney system can be used for every season in Korea climatic condition. Through this study, performance of solar chimney system for natural ventilation was verified by numerical method. Consequently, the solar chimney system is proved to be effective device for natural ventilation utilizing at all times, and the additional studies should be made through the experimental method for imagineering and commercialization.

• Journal of the Korean Society of Industry Convergence
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• 제5권4호
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• pp.313-320
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• 2002

A 2-dimensional $k-{\varepsilon}$ numerical model was developed to explore the effects of vehicle movement, jet fan and wind speed for the ventilation of road tunnels. To consider the temperature distribution in the tunnel, the energy equation was solved with a source term of the energy exhausted from vehicles. Although the tunnel ventilation can be made by the piston effect of vehicle movement, an additional ventilation is necessary when a head wind is existing. Jet fans may assist the air flow in the tunnel. However, more efficient ventilation system should be necessary, because the exhaust gas from vehicles flow along the road surface and it cannot be diffused in the longitudinal tunnel.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• 제28권2호
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• pp.190-199
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• 2018

Objectives: The purpose of this case study is to assess the current airflow and find the ideal ventilation conditions in tank reactors for minimizing the possibility of exposure respiratory dusts(size of $2.5{\mu}m$, $10{\mu}m$) when workers exchange catalysts in the tank reactors. Methods: A Numerical study was performed to determine ideal ventilation conditions, We considered two sizes of airborne respiratory particles($2.5{\mu}m$, $10{\mu}m$) at 12points from the bottom of tank reactor. We changed input & output ventilation conditions and analyzed the particle motion in the tank reactor. The star-ccm+, computational fluid dynamics tool was used to predict air & particle flow patterns in the tank reactor and a numerical simulation was achieved by applying the realized ${\kappa}-{\varepsilon}$ turbulence model and the Lagrangian particle tracking method. Results: From the results, the increase of recirculation air had a significant impact on removing dusts because they are removed by HEPA filter. To the contrary, Increasing the clean air quantity or changing the input position of clean air is not good for workers because it causes the exit of respiratory dusts through workers' entrance or cause it to remail suspended in the air in the workplace tank.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권1호
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• pp.22-37
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• 2016

This article investigates numerical modeling of surface piercing propeller (SPP) in unsteady open water condition using boundary element method. The home code based on BEM has been developed for the prediction of propeller performance, unsteady ventilation pattern and cross flow effect on partially submerged propellers. To achieve accurate results and correct behavior extraction of the ventilation zone, finely mesh has generated around the propeller and especially in the situation intersection of propeller with the free surface. Hydrodynamic coefficients and ventilation pattern on key blade of SPP are calculated in the different advance coefficients. The values obtained from this numerical simulation are plotted and the results are compared with experiments data and ventilation observations. The predicted ventilated open water performances of the SPP as well as ventilation pattern are in good agreement with experimental data. Finally, the results of the BEM code/experiment comparisons are discussed.