• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.10
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• pp.695-702
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• 2007

In this paper, the ventilation efficiencies of an underground sewage disposal plant were investigated for ventilating system without fan, ventilating system with eleven cross flow fans and ventilating system with sixteen cross flow fans by numerical method. It has been found that the air change effectiveness of the system without fan was predicted 0.44. It means that an additional ventilating equipment is needed to maintain good indoor air quality. For the ventilating system with sixteen cross flow fans, the air change effectiveness was predicted 0.55. The air change effectiveness of the ventilating system with eleven cross flow fans was predicted 0.51. It is known that the air change effectiveness above 0.5 is enough to eliminate pollutant and bad smell in the indoor. Therefore, it is recommended to select the ventilating system with eleven cross flow fans for the underground sewage disposal plant in an economic point of view.

• Fire Science and Engineering
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• v.22 no.1
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• pp.61-67
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• 2008

This study is focused on the numerical predictions of heat and smoke exhaust characteristics in an underground subway station stopping a fire train. Various ventilation operating modes with the fan equipped the platform and tunnels are considered. Distributions of temperature, carbon monoxide and visibility at a height of 1.7 m(breath height) above the platform are analysed for different ventilation fan operation mode. The numerical results show that smoke and heat is rapidly removed through tunnel by operating the tunnels fans. We suggested that during evacuation of passengers is not completed, the ventilation system in the platform is activated. After completion of passenger evacuation tunnel fans are activated but the fans in the platform are stopped.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.11
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• pp.1035-1043
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• 2004

For a long road tunnel, a tunnel ventilation system may be used in order to reduce the pollution level below the required level. To control the tunnel pollution level, a closed loop control algorithm may be used. The feedforward prediction algorithm and the cascade control algorithm were developed to regulate the CO level in a tunnel. The feedforward prediction algorithm composed of the traffic estimation algorithm and the CO density prediction algorithm, and the cascade control algorithm composed of the jet fan control algorithm and the air velocity setpoint algorithm. The verification of control algorithms was carried out by dynamic models developed from the actual tunnel data. The simulation results showed that control algorithms developed for this study were effective for the control of the tunnel ventilation system.

• Journal of the Korean housing association
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• v.16 no.1
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• pp.73-79
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• 2005

The ventilation efficiency of apartment housing bathroom has been measured by the flexible's diameter, length, and installation format to the exhaust In. The gas density attenuation method of Tracer Gas Method has been specifically utilized for this measurement. Full size mock-up of apartment housing bathroom, which was approximately $100 m^2$ in size, has been established for the ventilation emciency measurement. In addition, the ventilation efficiency has been studied by the possibility of air-supply In. The diameters of flexible are 100 mm, 125 mm, and 150mm. It also have the length of 1.0m, and 1.5 m. The installation formats are I shape, L shape, and S shape. As a result of this measurement, the flexible which has the highest ventilation efficiency was the one has bigger diameter, short in length, and I shape installation format.

• Journal of Biosystems Engineering
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• v.31 no.3 s.116
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• pp.175-181
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• 2006

Nursery pig building is imperative to provide environmental conditions favorable to maintenance of piglet health and the efficiency of growth rate. To meet the ultimate goal, it is necessary to apply proper ventilation design and construction to a confinement livestock building. This study was conducted to investigate the performance of a modified ventilation system in terms of devised slot-inlet (modification I) and exhaust fan (modification II) to improve air change rate in a confined nursery pig building, with dimension of 5.9 m(W) ${\times}$ 12.6 m(L) ${\times}$ 2.2 m(H) in an Darby Genetic Station. The experiment was carried out in August, especially when the outdoor peak temperature were above $30^{\circ}C$ and the measured indoor environmental factors were temperature, air velocity, humidity and ammonia concentration which have been known to affect the piglet health and growth. There was no difference in indoor temperature between the original and modified ventilation systems, however the air velocity and ammonia concentration in confined nursery pig building with modified ventilation system were, in most cases, better performance than original ventilation system. Therefore, it was concluded that the slot-inlet system that kept indoor environmental factors pertinent and had an economic advantage, should be considered as a ventilation system for decreasing sensible heat from piglet in confined nursery pig building during extreme summer season.

• The KSFM Journal of Fluid Machinery
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• v.13 no.3
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• pp.59-64
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• 2010

To analyze the three-dimensional flow in tunnel caused by operation of jet fan, both experimental and computational studies have been conducted. The experimental analysis of tunnel flow induced by jet fan is conducted on a real-scale apparatus with jet fan and tunnel, and air velocity at the monitoring points is measured for variation of fan's RPM. The three-dimensional numerical analysis including tunnel and jet fan is carried out for the same geometric configuration as the experimental analysis. The experimental and computational results are compared to examine the applicability of the numerical method.

• Tunnel and Underground Space
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• v.27 no.1
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• pp.12-25
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• 2017

In local underground mines heavily depending on the natural ventilation, ducted fan auxiliary ventilation system is strongly recommended instead of the total mine ventilation system requiring large capital and operating costs. Optimizing the installation of ducted fans in series in long large-opening mines is required to assure the economy and efficiency of the ventilation system. The two most critical design parameters for optimization are the wall separation distance and gap length between adjoining ducts. This study aims at deriving the optimal values for those two parameters concerning the economic and environmental aspects through the extensive CFD analysis, which minimizes pressure loss, leakage and entrainment of the contaminated air in the gap space. The ranges of the wall separation distance and gap length for study are selected by taking into consideration the existing recommendations and guidelines. The ultimate goal is to optimize the auxiliary ventilation system using ducted fans in series to provide a reliable and efficient solution to maintain clean and safe workplace environment in local long underground mines.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.8
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• pp.763-771
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• 2011

An optimization procedure for the design of a ventilation axial-flow fan is presented in this paper. Flow analyses of the preliminary fan are performed by solving three-dimensional Reynolds-averaged Navier-Stokes equations via a finite-volume solver with the shear-stress transport turbulence model as a turbulence closure. Three variables, the hub-to-tip ratio and the stagger angles at the mid and tip spans, are selected for the optimization. The Latin-hypercube sampling method as a design-of-experiments technique is used to generate twenty-five design points within the design space. and the weighted average surrogate models, WTA1, WTA2, and WTA3, are applied for find optimal designs. The results show that the efficiency is considerably enhanced.

• Journal of Bio-Environment Control
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• v.14 no.2
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• pp.76-82
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• 2005

Evaporative cooling pad system is one of the main cooling methods in greenhouses and its efficiency is very high. However, it has some disadvantages such as greenhouse temperature distributions are not uniform and installation cost is expensive. In this study, a CFD simulation model f3r predicting the air temperature distribution in the fan and fad cooling greenhouse was developed. The model was calibrated and validated against experimental data and a good fit was obtained. The influence of different outside wind, fan and pad height, ventilation rate, shading, and greenhouse length, were then examined. In order to reduce the internal temperature gradients, it is desired that the prevail wind direction and the fan and pad heights are considered. The simulation indicates that high ventilation rates and shading contribute to reduce the temperature gradients in the fan and pad cooling greenhouse. In order to maintain the desired greenhouse temperature, the pad-to-fan distance should be restricted according to the design climate conditions, shading and ventilation rates. The developed CFD model can be a useful tool to evaluate and design the fan and pad systems in the greenhouses with various configurations.

• Journal of Korean Society of Disaster and Security
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• v.12 no.2
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• pp.47-56
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• 2019

Recently, in order to overcome the difficulty of entering a fire source due to the occurrence of a large amount of smoke in the event of a fire in a parking lot, it has used that a method of discharge smoke using air supply, exhaust fans and jet fans installed for ventilation of parking lots. In this study, the variation of flow in the smoke layer was observed using CCTV under two conditions, in which only the air supply fan operates and the manned fan operates together, and the temperature around the plume was compared to Albert eq. to assess its suitability as a parking lot ventilation performance evaluation method. As a result, it was found that the smoke layer could be disturbed if the Jet Fan was operated at the same time, which could lead to the possibility of an initial evacuation disturbance. However, the additional operation of the Jet Fan has been confirmed by the observation CCTV that the emission performance is improved, which is believed to help conduct the suppression operation. The temperature around the plume was measured and compared to Alpert eq, and was analyzed to be about $2^{\circ}C$ lower at the center axis of the plume and $9.0^{\circ}C$ higher at 8 m in the direction of the discharge of smoke. The results of temperature measurements around the plume were lower than the maximum temperature expected in AS 4391 and did not exceed the expected temperature risk caused by the experiment. As with these results, the temperature risk from the progression of hot smoke tests is foreseeable, so it will be available as one of the general evaluation methods for assessing smoke control performance in a parking lot without relevant criteria.