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황세준(Sejoon Hwang),박원규(Warngyu Park) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
While stamping process, air may be trapped between die and blank and it builds up high pressure. This induces the imperfections on the blank surface and makes extreme high tonnage of punch required to reach home position. To prevent these problems, the air ventilation holes are drilled through the die. But, most of die makers drill air ventilation holes excessively on trial and error basis. The present work has developed a simplified mathematical formulation for computing the pressure of air pocket at given cross-sectional area of air ventilation holes and the pressure of air pocket was compared to commercial CFD code and experiments. The pressure was well agreed with the result of CFD code and experiments. The present work could also calculate the optimum cross-sectional area of the air ventilation hole not to exceed the prescribed maximum pressure of air pocket by using the Bisection method.
황세준(Sejoon Hwang),박원규(Warngyu Park),김철(Chul Kim),오세욱(Sewook Oh),조남영(Namyoung Cho) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
In sheet metal forming process using press and draw die some defect can be made because of the high pressure of air pocket between draw die and the product. The purpose of this study is to develop a program to decide an optimal combination of air vent hole size and number to prevent those defect on product. The air inside air pocket is considered as ideal gas and the compression and expansion is assumed as isentropic process. The mass flow is computed in two flow condition: unchocked and chocked condition. The present computation obtains required cross-sectional area of air vent hole for not exceeding the user specified pressure such as the pressure for yielding strength of the product or the pressure for unchocked flow. To validate the program the present results are compared with the results of other researchers and commercial CFD code.
[차량운동성능부문] 후미경사각 변화에 따른 자동차 저저항 설계에 관한 수치적 연구
강동민(Dongmin Kang),이종칠(Jongchil Lee),박원규(Warngyu Park),정영래(Youngrae Jung) 한국자동차공학회 2000 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In this paper, numerical analysis is used to find the effects of rear end slant angle acting on low drag design of an automobile. The rear end slope angles used in this study are 24', 26.6', 28.6', 31.6', 36.4'. The governing equations of the 3-D incompressible Navier-Stokes equations are solved by the iterative time marching scheme. The computed surface pressure coefficients have been compared with experimental results and a good agreement has been achieved. The A- and C-pillar vortex and other flow phenomena around the ground vehicle are evidently shown. The variation of aerodynamic coefficients of drag, lift with respect to rear end slant angle are systematically studied.
김주영(Jooyoung Kim),김준홍(Joonhong Kim),한명철(Myungchul Han),박원규(WarnGyu Park),장기룡(Kilyong Jang) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Since the mist of the automobile windshield interferes the driver's sight and safety, it is needed to develop an automatic de-mist equipment with coupling of the Automatic Temperature Control (ATC) unit of an automobile. To be able to coupling between units, we have used RS232C and made the interface board which can communicate between them despite of the difference of communication speed. The Mist possibility (MP) was as the difference of temperature between the dew point and the surface temperature of windshield glass. The automatic de-mist control system begins to operate before the mist covers the inner windshield glass. It was observed that the automatic de-mist control system operates well and removes quickly the mist as long as possible.
[열유체부문] 수치적 기법을 이용한 자동차 Defrost 노즐 유동을 위한 설계인자 연구
배인호(Inho Bae),강규태(Kutae Kang),황지은(Jieun Hwang),박원규(Warngyu Park),장기룡(Kilyong Jang) 한국자동차공학회 2001 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2001 No.11_1
Velocity profile and its magnitude affect greatly to defrosting and demisting in the windshield. In this paper, the three dimensional flow analysis in the defrost nozzle which is geometrically complicated was performed to investigate and predict velocity profile of the nozzle outlet. The three dimensional Navier-Stokes code used in this case was validated by performing Of the generic A/C duct flow analysis successfully. The results of defrost nozzle flow analysis nearly coincided with experimental data. Based on the standard case, design factors were applied. Flow analysis was carried out with three different number of the guide vanes. The angle of the guide vane was applied to the nozzle outlet also. In the flow simulation inside the automotive, inlet velocity was provided by a exit velocity of the defrost nozzle. The investigation of the each case informed us which case could produce the best velocity profile to defrost. Through these procedure, the optimized design factor was found. Further more, this three dimensional incompressible code will be used to predict and compare with any kind of defrost nozzle flow.