• Title/Summary/Keyword: 에어 포켓

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Flow Analysis of the Air Pocket in Draw Die (드로우 금형의 에어포켓 유출 유동해석)

  • Hwang, Se-Joon;Park, Warn-Gyu;Kim, Chul;Oh, Se-Wook;Cho, Nam-Young
    • 유체기계공업학회:학술대회논문집
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    • 2006.08a
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    • pp.345-348
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    • 2006
  • 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.

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Prediction of Air Pocket Pressure in Draw Die during Stamping Process (드로우 금형의 에어포켓 수축에 따르는 내부공기 압력예측에 대한 연구)

  • Koo, Tae-Kyong;Hwang, Se-Joon;Park, Warn-Gyu;Oh, Se-Wook
    • Transactions of the Korean Society of Automotive Engineers
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    • v.16 no.6
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    • pp.10-18
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    • 2008
  • Metal stamping is widely used in the mass-production process of the automobile industry. During the stamping process, air may be trapped between the draw die and the panel. The high pressure of trapped air induces imperfections on the panel surface and creates a situation where an extremely high tonnage of punch is required. To prevent these problems, many air ventilation holes are drilled through the draw die and the punch. The present work has developed a simplified mathematical formulation for computing the pressure of the air pocket based on the ideal gas law and isentropic relation. The pressure of the air pocket was compared to the results by the commercial CFD code, Fluent, and experiments. The present work also used the Bisection method to calculate the optimum cross-sectional area of the air ventilation holes, which did not make the pressure of the air pocket exceed the prescribed maximum value.

Development of an Automated System for Predicting Shape and Volume of Air Pocket on the Draw Die (드로우 금형의 에어 포켓 형상 및 체적예측 자동화 시스템 개발)

  • Jung, Sung-Yuen;Hwang, Se-Joon;Park, Warn-Gyu;Kim, Chul
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.1
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    • pp.72-78
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    • 2008
  • Metal stamping is widely used in the mass-production process of the automobile. During the stamping process, air may be trapped between the draw die and the panel and/or between the punch and the panel. Air pocket rapidly not only increases forming load in the final stage, but also deforms the product just formed by compressive air inside the air pocket in knockout process. To prevent these problems air bent holes are drilled in the die to exhaust the trapped air but all processes associated with air bent holes are performed by empirical know-how of workers in the field due to lack of researches. Therefore this study developed an automated design system for predicting the shape and position, and volume of air pocket on the draw die by using the AutoLISP language under AutoCAD circumstance. The system is able to display the shape of air pocket occurred in the draw die and to calculate automatically its volume by strokes. So it makes a stepping stone to calculate theoretical size of an air bent hole and numbers according to it by predicting and analyzing the position and volume of air pocket. Results obtained from the system enable the designers or manufacturers of the stamping die to be more efficient in this field.

Development and Test of Gas Turbine Intake Air Filter Media (가스터빈 유입공기 정화용 에어 필터 여재 국산화 개발 기초 성능실험)

  • 박현설;박석주;김상도;최호경;임정환;박영옥
    • Proceedings of the Korea Air Pollution Research Association Conference
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    • 2000.11a
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    • pp.261-262
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    • 2000
  • 항공기나 발전용 가스터빈(gas turbine) 및 대용량 압축기(compressor) 등과 같이 흡입공기의 유량이 매우 클 경우, 유입되는 공기 내부에 함유된 입자상 오염물질은 터빈의 기계적 성능에 큰 장애를 일으킬 수 있다(Klink and Schroth, 1996, Schroth, 1993). 이러한 입자상 오염물질을 효과적으로 제어하기 위해서는 처리기체의 유입구 부분에 대형 공기 정화용 여과시스템이 요구되며, 일반적으로 카트리지형 에어 필터(cartridge air filter)나 포켓형(pocket), 카세트형(cassette) 에어 필터가 적용 현장의 조건에 따라 사용된다. (중략)

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Development of FEA Custom Application System for Thermal Stress Evaluation of Skirt Type Joint Pressure Vessel (압력용기 Skirt부의 열응력 평가를 위한 유한요소해석 전문가시스템 개발)

  • Ye, Gyoo-Hyeon;Park, Dong-Sung;Choi, Kyeong-Ho
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.2 no.1
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    • pp.51-56
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    • 2003
  • A custom application system, which was based on the finite element analysis, for stress on the head-skirt junction of a hot pressure vessel was developed. This is useful computer-based analysis system which designed to provide an analysis technique and knowledge conveniently available to other people. It was found the evaluation of thermal stress of several typed skirt joint of a pressure vessel could be performed early using this system.

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Study on air pocket design of thrust bearing for high-stiffness air spindle (공기 주축 고강성화를 위한 스러스트 베어링의 에어포켓 설계에 관한 연구)

  • Han, Young-Chil;Lee, Chae-Moon;Lee, Deug-Woo;An, Dae-Geun
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.998-1002
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    • 2003
  • This paper investigates the characteristics of stiffness and load in the thrust bearing of spindle which could be changeable according to the groove shape of inlet, in order to design a high-stiffness air bearing by selecting a optimal groove shape. In experiments, dead weight and displacement sensor are used to measure the load carrying capacity and the stiffness respectively. Various shapes and different depth of groove of self-restrictor are used as experimental conditions. Comparative study between the theoretical value and the practical one by measuring the value of stiffness and load of the thrust bearing is performed.

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A Study on Slamming Impact Pressure (슬래밍 충격 압력에 대한 연구)

  • Park, Jun-Soo;Oh, Seung-Hoon;Kwon, Sun-Hong;Chung, Jang-Young
    • Journal of Ocean Engineering and Technology
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    • v.23 no.1
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    • pp.67-73
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    • 2009
  • This study presents the results of a slamming experiment using a pneumatic cylinder. The employment of the pneumatic cylinder showed a relatively good repeatability when the results were compared with those of other slamming devices. The experiment was done for various incident angles. An air pocket was believed to cause a reduction in the magnitude of the impact pressure with an incident angle of $0^{\circ}$ for the water entry. A high speed camera was used in an attempt to locate the time of the contact between the bottom of the specimen and the free surface. It seemed that the maximum pressure occurred before the water contacted the bottom of the specimen.

An Experimental Study on Compressibility Effect in Sloshing Phenomenon (압축성이 슬로싱 현상에 미치는 영향에 관한 실험적 연구)

  • Park, Jun-Soo;Kim, Hyun-Yi;Lee, Ki-Hyun;Kwon, Sun-Hong;Jeon, Soo-Sung;Jung, Byoung-Hoon
    • Journal of Ocean Engineering and Technology
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    • v.23 no.4
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    • pp.12-18
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    • 2009
  • The present study focused on the compressibility of partially filled fluids in a sloshing tank. Filling ratios ranging from 18% to 26% were used to find compressible impact on a vertical wall. The model test was for 1/25 scale of a 138 K LNGC cargo tank. To investigate the two dimensional phenomenon of sloshing, a longitudinal slice model was tested. A high speed camera was used to capture the flow field, as well as the air pocket deformation. The pressure time history synchronized with the video images revealed the entire compressible process. Three typical impact phenomena were observed: hydraulic jump, flip through, and plunging breaker. In particular, the pressure time history and flow pattern details for flip through and plunging breaker are presented.

Design and Evaluation of Intelligent Helmet Display System (지능형 헬멧시현시스템 설계 및 시험평가)

  • Hwang, Sang-Hyun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.45 no.5
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    • pp.417-428
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    • 2017
  • In this paper, we describe the architectural design, unit component hardware design and core software design(Helmet Pose Tracking Software and Terrain Elevation Data Correction Software) of IHDS(Intelligent Helmet Display System), and describe the results of unit test and integration test. According to the trend of the latest helmet display system, the specifications which includes 3D map display, FLIR(Forward Looking Infra-Red) display, hybrid helmet pose tracking, visor reflection type of binocular optical system, NVC(Night Vision Camera) display, lightweight composite helmet shell were applied to the design. Especially, we proposed unique design concepts such as the automatic correction of altitude error of 3D map data, high precision image registration, multi-color lighting optical system, transmissive image emitting surface using diffraction optical element, tracking camera minimizing latency time of helmet pose estimation and air pockets for helmet fixation on head. After completing the prototype of all system components, unit tests and system integration tests were performed to verify the functions and performance.