• 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.

• 한국산업융합학회 논문집
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• 제23권2_2호
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• pp.343-349
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• 2020

As global warming accelerates due to global climate change, the International Maritime Organization(IMO) has set up Emission Control Area(ECA) and encourages the use of Liquefied Natural Gas(LNG). For this reason, as the demand for LNG increases, the demand and research of related equipment also increases. In this study, one of them, the vent mast for the discharge of LNG was studied. In general, vent mast receives various loads such as wind load, earthquake load and dead load during operation. Accordingly, consideration of these loads is essential for structural design and safety evaluation of the vent mast. In this study, the structural safety of the vent mast is evaluated by performing finite element analysis. As a result, the structural safety evaluation results were analyzed based on the database of materials of the vent mast, and the stress level was analyzed to provide a design guide.

• 한국신뢰성학회지:신뢰성응용연구
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• 제13권1호
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• pp.45-53
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• 2013

In this paper, we analyze the failure mechanism of the washer pump to find what is the failure cause in the road environment. The statistics show the field common failure mode is inner corrosion. The failure mechanism is assumed that the inner part of washer pump is corroded due to inflow of moisture through vent hole. To prevent the failure, we can think a method that is covering the vent hole. In general, the vent hole is designed to play an important role in an automobile parts. So, we need to prove the vent hole is not necessary. The first purpose of this paper is to make sure that the vent hole does not affect the durability of washer pump using the analysis of operating condition. The second purpose is to compare the durability properties if the vent hole is covered.

• 한국안전학회지
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• 제20권3호
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• pp.71-77
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• 2005

This study aims to find the safe vent area to prevent a destruction of building by gas explosion in a building. Explosion vessel which used in this experiment is 1/5 scale down model of simple livingroom and its dimension is 100cm in length 60cm in width and 45cm in height. Liquified petroleum gas(LPG) was injected to the vessel to the concentration of 4.5vol%, and injection rate were varied in 1L/min or 4L/min. Gas mixture was ignited by the 10kV electric spark. For analysis the characteristics of vented explosion pressure according to the vent size and vent shape, its size and shape were varied. From the experiment, it was found that explosion pressure in the vented explosion :in affected by the gas injection rate, vent area and vent shape. And the vent area to volume ratio(S/V) to prevent the building destruction by explosion pressure, it is recommended that the design of vent area happened by the explosion should be above 1/500cm in S/V. And if the vent area has complicate structure in same area, vented explosion pressure will be higher than a single vent, and possibility of building destruction will increase. Therefore to effectively vent the explosion pressure for protect a building and residents from the gas explosion hazards, the same vent area should have a singular and constant shape in the cross-sectional area of the vessel.

• 대한치과기공학회지
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• 제16권1호
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• pp.5-11
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• 1994

On purpose of relative comparison of between air-vent attached pattern and non attached one, casting tests were accomplished by castability analysis unrig wax screen mesh pattern. Experimental specimens are divided Into 4groups. 1) Air-vent attached pattern with high casting pressure(coil spring type centrifugal casting machine 2.5turn). 2) Air-vent attached pattern with low casting pressure(coil spring type centrifugal casting machine 1.5turn). 3) Air vent non attached pattern with high casting pressure(coil spring type centrifugal casting machine 2.5turn). 4) Air-vent non attached pattern with low casting pressure(coil spring type centrifrgal casting machine 1.5turn). The main results are as follows : 1) The condition of high casting pressure no.1, no.3 were showed perfect castability. 2) The condition of low-casting pressure, there is a wide difference between no.2, no.4 group. Castability of no.2 group preferable to no.4 group(p<0.001). 3) Low casting pressure and complex shape cause the low-castability. So it is recommanded that use of air-vent in case of complex shaped wax pattern with low easting pressure.

• 한국안전학회지
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• 제14권3호
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• pp.40-47
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• 1999

A numerical study on gaseous explosion was carried out to predict the transient pressure behavior with the partial rupture in confined vessels. Equations, assumptions and solutions for central ignition of premixed gases in closed spherical vessels are proposed with various equivalence ratios of gas fuel, as $CH_4$ and $C_3H_8$, vent areas and vent opening pressures. Given vent opening pressure in a vessel, the magnitude of second peak pressure results from the vent areas and burning velocity, varied by equivalence ratio of gas fuel. In a living room of an apartment, the higher second peak pressure than the vent pressure is not appeared due to its large window areas. As vent opening pressure is higher, the larger damage by gaseous explosion is expected and the larger vent area is necessary for relieving the damage. In the same concentration, the gaseous explosion by propane rather than methane shows the larger damage due to its higher adiabatic flame temperature and equivalence ratio.

• 한국정밀공학회지
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• 제23권2호
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• pp.122-128
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• 2006

This study focuses on a performance improvement of the vent silencer using acoustic analysis. Since the vent silencer is generally used for a high level shock noise, it should be designed to reduce a wide frequency band noise. In the designing stage of the vent silencer, structural shapes of diffuser and splitter are the most significant design parameters. Effects of modifying the original structure of the diffuser and the splitter are analyzed and evaluated. From the results, It is found that the diffuser with two pipes and double-step structure more effectively reduces a wide frequency band noise but the increment of the number of splitters is not desirable.

• 한국유체기계학회 논문집
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• 제19권5호
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• pp.42-49
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• 2016

Aerodynamic analysis of a low-voltage electric motor has been performed with various inlet vent shapes. Effects of inlet vent shape on aerodynamic performance of a motor cooling fan have been investigated numerically using three-dimensional Reynolds-averaged Navier-Stokes equations. The k-${\varepsilon}$ turbulence model was used for the analysis of turbulence. The finite volume method and unstructured tetrahedral grids were used in the numerical analysis. Optimal grid system in the computational domain was selected through a grid-dependency test. From the results of the flow analysis, considerable energy loss by flow separation was observed in the flow passage. It was found that mass flow rate through the cooling fan in the low-voltage motor can be increased by modifying the inlet vent shape. And, some inlet vent shapes were suggested to improve the aerodynamic performance of the motor cooling fan.

• 대한치과보철학회지
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• 제32권1호
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• pp.171-178
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• 1994

This paper reports histologic and histomorphometric results concerning bone healing around vent area of 16 titanium plasma sprayed IMZ implants in rabbit femurs. Bone contact around the implants 8 weeks after placement showed a great deal of variability from 14.32% to 65.94% and mean total bone contact was 33.96%. The mean percent amount of bone contact was 43.68% in inner surface of vent and 27.79% in outer surface. Histologic examination of horizontal sections of vent area showed direct contact with living lamellar bone and some woven bone. The implants surface area not in contact with bone was in contact with collagenous connective tissue. But there was no sign of foreign-body reaction.

• 한국가시화정보학회지
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• 제8권1호
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• pp.25-30
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• 2010

The flow characteristics under recirculation cool vent mode is numerically studied using commercial fluid dynamic code(CFX). For the reliable analysis, real vehicle and human FE model is employed in grid generation process. The geometrical location and shape of panel vent, and exhaust vent is set as that of real vehicle model. The flowrate of the working fluid is determined as 330CMH which is equivalent to 70 percent of maximum capacity of HVAC system. The high velocity regions are formed around 4 each panel vent. Because of the non-symmetrically located exhaust, non-uniform flow and partial backflow near the door trim is observed. Streaklines start from each panel vent show the flow pattern of the airflow in the passenger's compartment very well.