• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.383-384
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• 2006

Ventilated disc was improved for reducing judder and heat. But the crack among vent holes occurs due to stress concentration. We investigate the stress distribution of vent holes. The vent holes with shape of a right angle, a chamfer and rounding was analyzed. The result of FEA was that rounded vent holes have a minimum stress. Also Maximum stress distributed within holes. Therefore We suggest that the rounded vent holes is good to reduce the crack.

• 한국가시화정보학회:학술대회논문집
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• 2006.12a
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• pp.17-20
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• 2006

Passenger safety is fundamental factor in automobile. Among much equipment for passenger safety, the air bag system is the most fundamental and effective device. Beside of the front air bag system which installed on most of all automobiles, a curtain-type air bag is increasingly adapted in deluxe cars fur protecting passengers from the danger of side clash. Curtain type airbag system consists of inflator housing, fill hose, curtain airbag. Inflator housing is a main part of the curtain-type air bag system for supplying high-pressure gases to deploy the air bag-curtain. Fill hose is a passageway to carry the gases from inflator housing to each part of curtain airbag. Therefore, it is very important to design the vent holes of fill hose for good performance of airbag deployment. But, the flow information from vent holes of fill hose is very limited. In this study, we measured instantaneous velocity fields of a high-speed flow ejecting from the vent holes of fill hose using a dynamic PIV system. From the velocity Held data measured at a high frame-rate, we evaluated the variation of the mass flow rate with time. From the instantaneous velocity fields of flow ejecting from the vent holes in the initial stage, we can see a flow pattern of wavy motion and fluctuation. The flow ejecting from the vent holes was found to have very high velocity fluctuations and the maximum velocity was about 480m/s at 4-vent hole region. From the mass flow rate with time, the accumulated flow of 4-vent hole has occupied about 70% of total flow rate.

• Korean Journal of Computational Design and Engineering
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• v.14 no.5
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• pp.330-337
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• 2009

Nowadays a lot of high-tech electronic products such as TVs, monitors and camcorders are being developed. The more functions the electronic devices have, the more heat problems occur. Therefore, most of electronic products have air-ventilation holes to eliminate heat that is generated inside the products. The shapes of ventilation holes are usually complicated since aesthetic appearance of the products is important these days. In order to create those complicated shapes, designers should do time-consuming jobs because most of commercial CAD systems do not provide the functions that create patterns of lofted parts along freeform surfaces. In this research, an automated air-ventilation hole modeling system was proposed. The system generates patterns of lofted objects on freeform surfaces. Standard process to create air-ventilation holes manually was established, and vent-hole types and pattern types were classified into several categories. Designers can create many kinds of vent-holes by combining vent-hole types and pattern types. Users can also utilize user-defined pattern which can give users more flexibility. Developed system was applied to several design examples and the results are presented.

• Journal of Biosystems Engineering
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• v.20 no.4
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• pp.360-367
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• 1995

The effect of air vent holes, stacking methods of boxes and clearance between boxes on static pressure drop, were measured to design of pressure cooling system. Static pressure drops in air vent hole of carton box were measured for different hole opening ratio from 1% to 5%. Static pressure drop was expressed as a function of superficial velocity as second-degree polynomial. At given static pressure in plenum chamber, static pressure drop in boxes was shown as second-degree polynomial of the number of carton box in series stacking method, as first-degree polynomial in height and parallel stacking method. In pressure cooling of 24 boxes of Tsugaru apple, air flow rates through clearance between the boxes were shown 1.27 and 1.65 times than those of through the inside of boxes at the plenum pressure of 10mmAq and 20mmAq, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.6
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• pp.1141-1149
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• 2007

This paper describes two major techniques; image processing and gas vent insert and rejection control, for efficient gas vent exchange and holes detecting on the shoes mold. The key idea is to detect holes on the mold to select which holes to insert and to reject automatically guide center of hole's position. This allows us to save labor time while minimizing defective rate of PU shoes mold forming and production costs for gas vent exchange such as insertion and rejection.. Our experimental results have demonstrated that the hole's detection and gasvent exchange mechanism are more efficient and provide accurate mechanism to mitigate risks of vent injection/rejection failures.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.896-905
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• 1996

Pressure drop, as a function of air flow, was measured for tomatoes and mandarins in bulk with different sizes, stacking arrangements and bed porosities. Pressure drop was also measured on carton vent holes and on a carton of packed fruits . and the cumulative effects of air flow resistance of vent holes and packed fruits in bulk on the air flow resistance of a carton of fruits were evaluated . Equation were presented to describe pressure drop bulk fruits, of an empty carton and of a carton of packed fruits as related to the air velocity , the bed porosity, the fruit diameter and the opening ratio of the vent hole.

• Fire Science and Engineering
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• v.26 no.5
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• pp.99-104
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• 2012

This study investigated the pressure change in the fire room and elevator lobby during the air pressurization to the Elevator lobby with the various egress scenarios and the existence of vent holes in the fire room. The experiments revealed that pressure change was significantly affected by the open/closure scenarios of the front door and stairway door resulting in over pressure, under pressure and performance drop of the door closure. It also revealed that the required smoke defensive air velocity can be obtained only with the existence of vent holes in the fire room by the removal of back pressure in the fire room.

• Journal of Sensor Science and Technology
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• v.15 no.1
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• pp.20-27
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• 2006

This paper presents a gas measurement system for deciding hole positions on a PU middle-sole mold from computed gas amount. The optimal number of holes and their positions on the shoe mold are decided from statistical experiment results to overcome the problem of excessive expenses in gas vent exchange. This paper also describes a gas vent exchange mechanism using computer vision system. The gas hole detecting process is based on computer vision algorithms represented as a simple Pattern Matching. The experimental result showed us that the system was useful to calculate the number of holes and their positions on the shoes mold.

• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.150-161
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• 2005

A test was performed to collect the data to validate an analytic method for vent hole sizing on the nose fairing of a launch vehicle. The bake-out chamber at KARI was used to simulate the ambient pressure drop, and pressure difference data were collected for a model with various kinds of vent holes which was installed in the chamber. The characteristics of the test facility and measurement equipments were evaluated for the measurement of the transient behaviors. The measured data were processed in consideration of the characteristics of the facility and equipments, and the effects of vent hole size and configuration on the pressure variation in the model were analyzed based on the data.

• Transactions of Materials Processing
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• v.20 no.5
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• pp.377-386
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• 2011

During stamping processes, the air trapped between sheet metal and the die cavity can be highly compressed and ultimately reduce the shape accuracy of formed panels. To prevent this problem, vent holes and passages are sometimes drilled into the based on expert experience and know-how. CAE can be also used for analyzing the air behavior in die cavity during stamping process, incorporating both elasto-plastic behavior of sheet metal and the fluid dynamic behavior of air. This study presents sheet metal forming simulation combined simultaneously with simulation of air behavior in the die cavity. There are three approaches in modeling of air behavior. One is a simple assumption of the bulk modulus having a constant pressure depending on volume change. The next is the use of the ideal gas law having uniform pressure and temperature in air domain. The third is FPM (Finite point method) having non-uniform pressure in air domain. This approach enables direct coupling of mechanical behavior of solid sheet metal and the fluid behavior of air in sheet metal forming simulation, and its result provides the first-hand idea for the location, size and number of the vent holes. In this study, commercial software, PAM-$STAMP^{TM}$ and PAM-$SAFE^{TM}$, were used.