• International Journal of Air-Conditioning and Refrigeration
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• v.17 no.2
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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.

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.37.3-37.3
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• 2008

• Journal of computational fluids engineering
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• v.17 no.1
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• pp.36-43
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• 2012

When a high-speed train passes an underground station, large pressure waves are generated due to the piston effect. These pressure waves can cause the problems of vibration and noise as well as the ear discomfort of passengers at the underground station. This work numerically analyzed the pressure wave generation and propagation in an high-speed railway underground station, and the optimal location for vent shafts was studied to improve the passenger comfort by reducing the magnitude of the pressure wave and its rate of change. The evolution of pressure field in the underground station was calculated using a CFD(Computational Fluid Dynamics) software(Fluent), where the axis-symmetric two-dimensional model verified by Wu was used. And this study is applied to modelling of the underground station and the tunnel from Daegok station A-line of GTX(Great Train Express). From the result, we can have a conclusion that the role of vent shafts respectively were different according to the position in and out the underground station. Also Vent shaft in the underground station widely reduced pressure magnitude. And vent shaft out underground station reduced initial pressure peak value. Double vent shafts installed at tunnel toward station entrance and inside of the tunnel are the most efficient to reduce pressure. and pressure reduction increases according to the number of vent shaft.

• Journal of Bio-Environment Control
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• v.4 no.2
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• pp.232-239
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• 1995

This study was carried out to get required torque data needed to design and develop a roll-up ventilation system in a pipe-constructed plastic film green-house. The results obtained from this study are as follows : 1. The required torques of a roll-up ventilation system in greenhouse are the functions of its length. The torques should multiplied by the conversion coefficients (2.0 in ceiling vent, 1.8 in side vent) in case of application. 2. In constructing pipe-constructed plastic film greenhouse, a shaft pipe is the largest essential element in roll - up shaft weight constitution which have an effect on the required torques. Therefore, the pipe should be light using nonferrous materials like aluminum alloy. 3. A planetary reduction ventilator of differential ring gear type is suitable for a roll-up ventilation system, because it can make high efficient reduction just using the first step shift.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.2
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• pp.135-141
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• 2004

The present paper concerns a smoke movement in a tunnel fire with a vertical shaft. The model tunnel measured 13.4m long, 0.4m wide and 0.4m high. The cross section is 1： 20 of a full scale tunnel. Ethanol was used as a fuel. The fire size in model tests varied from 1.35 kW to 13.37 kW, which corresponds to full scale fires of 2.41 to 23.91 MW. Smoke front velocity and temperatrue were decreased due to the vertical shaft install. Temperature was reduced maximum about 2$0^{\circ}C$ at ceiling and about 23$^{\circ}C$ at vertical position. CO concentration was reduced as the vent width widened. When vent width was more than 15 cm, CO concentration was not reached 100 ppm. Descent degree of the smoke layer was confirmed through the visualization.

• International Journal of High-Rise Buildings
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• v.2 no.4
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• pp.341-344
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• 2013

During a building fire, smoke can flow through elevator shafts threatening life on floors remote from the fire. Many buildings have pressurized elevators intended to prevent such smoke flow. The computer program, CONTAM, can be used to analyze the performance of pressurization smoke control systems. The design of pressurized elevators can be challenging for the following reasons: (1) often the building envelope is not capable of effectively handling the large airflow resulting from elevator pressurization, (2) open elevator doors on the ground floor tend to increase the flow from the elevator shaft at the ground floor, and (3) open exterior doors on the ground floor can cause excessive pressure differences across the elevator shaft at the ground floor. To meet these challenges, the following systems have been developed: (1) exterior vent (EV) system, (2) floor exhaust (FE) system, and ground floor lobby (GFL) system.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.889-894
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• 2008

Exhaust system used in toilet and cooking place of high riser public house is roof fan of two basic types : natural roof ventilator and natural/forced roof ventilator. Natural/forced roof ventilator has a motor in the rotary shaft. There are many high riser public house in Korea. These buildings were not viewed as being major contributors to exhaust pollutants producted in indoor. It was because many engineers thought that exhaust in high riser building depend on stack effect. This study investigates on stack pressure determined by exterior pressure and the difference pressure control in exhaust stack used in high riser public house. This paper focuses mainly on the effect of the time interval for power supply of motor installed in roof fan with function of natural wind velocity and of exhaust air volume of toilet. It is observed there are higher exhaust efficiency than the existing natural roof ventilator.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.5
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• pp.527-537
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• 2016

Recent automakers are trying to be more precise with the dimension check and moving parts to guarantee high quality and satisfy customer requirements. The aim of this paper is to investigate the design tolerance suitability of door operating mechanism linked arms, lever, and cam-shaft in a mobile air handling unit. These parts are complicated because doors, arms, lever and cam-shaft are connected nonlinearly in 3D. The current tolerance analysis method poses problems in design analysis because the moving doors are reasonably suitable for the AHU function. The 3-DCS analysis method provided useful results not only in establishing the inspection criteria for the quality control of products but also in enabling economical production. As a result, the vent door had $1.62^{\circ}{\sim}1.72^{\circ}$ and the defrost door had $0.84^{\circ}{\sim}0.9^{\circ}$ for the directly connected arms operating-type. For the lever connected arm operating-type, the foot door had $2.0^{\circ}{\sim}2.24^{\circ}$ tolerance, while the tolerance values satisfied the air flow volume distribution rate criteria in the AHU. Finally, the results have confirmed the design's tolerance suitability by using 3-DCS analysis at the early design stages. Reliability can be achieved by analyzing accumulated tolerance during the sub-parts assembly process and the moving mechanism linked especially by arms, lever, and cam-shaft.

• Transactions of Materials Processing
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• v.8 no.5
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• pp.491-497
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• 1999

The effect of partial squeeze on the quality of casting products in the vacuum die casting was investigated to make defect free casting products with excellent mechanical properties. The partial squeeze and vacuum die casting process was industrially implemented in making reaction shaft support which was made of a hypereutectic Al-15%Si alloy. To combine squeezing and vacuum effects, the plunger injection system was designed and attached on the chill vent type vacuum machinery system. The combination of vacuum effect before injection and partial squeezing effect after injection resulted in defect free die casting products. The uniform distribution of fine eutectic and proeutectic Si obtained from trial process also provided excellent mechanical properties.

• Fire Science and Engineering
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• v.17 no.2
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• pp.62-69
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• 2003

The smoke control system in subway platform is not only using for smoke exhaust facility but also using ventilation system. For this reason, smoke vent effectiveness is depending on its position, ventilating volume capacity and the vent method. In this study, the passenger's evacuation time was calculated for the case of fire on sloped subway train vehicle in subway platform. In order to recommend the mechanical smoke exhaust operation mode, SES (Subway Environmental Simulation) was used to predict the airflow of the inlet and outlet tunnel for the subway station. Fire dynamics Simulator(FDS) was used the SES's velocity boundary conditions to calculate the smoke density and temperature under the condition of fire on stopped subway train vehicle at the platform. We compared smoke density and temperature distributions for each 6 types of smoke exhaust systems to clarify the characteristics of smoke and hot air exhaust effectiveness from the result of fire simulation.