• 소성∙가공
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• 제17권4호
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• pp.278-283
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• 2008

This paper concerns the die face design for a heat protect panel aided by the finite element forming analysis in order to eliminate the surface defect and to improve the surface quality. The CAE procedure of the stamping process is introduced in order to reveal the reason of surface inferiorities and to improve surface quality. Complicated shape of the product induces the surface inferiorities such as wrinkling due to the insufficient restraining force of the forming blank and the non-uniform contact of the blank with the tools. This paper proposes a new guideline for the die design which includes the modification of tool shapes and addition of the draw-beads on the tool surface for ensuring the increased the restraining force with the uniform contact condition. The effectiveness of the proposed design is verified by the forming analysis and is confirmed by the tryout operation in the press shop. The analysis and test results show that the modified process parameters such as tool shapes and draw-beads can reduce the tendency of wrinkling and improve surface quality.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.87-90
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• 2005

The drawbead is used to control the material flow into the die and increase the forming quality during the binder wrap process and the stamping process in the sheet metal forming. Drawbead restraining force (DBRF) is controlled by geometrical parameters and influenced by process parameters such as friction coefficient and blank thickness. In order to inspect the effect of process parameters, parameter studies are performed with the variation of parameters using finite element model of drawbead which is utilized reliably for the calculation of the drawbead restraining force. Drawbead analysis is carried out with 2-D plane-strain element and 3-D shell element. After the verification of the accuracy of the drawbead model with 3-D shell element, it is utilized to the prediction and the investigation of the effect of process parameters. The result of parameter studies can be utilized to the die design in the tryout stage.

• 한국의사학회지
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• 제21권2호
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• pp.115-122
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• 2008

Ma Gwa Hwe Tong, or 麻疹會通 is a general medicinal classic on measles which was an attempt to cope with the situation in the later Joseon Dynasty, when measles was prevailing all throughout the country. It was written in 1798 by Jung Yak Yong, who was a famous realist and a distinguished scholar, and in one of the chapters called Oh Gyun Pyun shows his thoughts. What he is trying to do through his writings, Ma Gwa Hwe Tong, was not reforming the current medicinal studies but to organize the classics on measles that he had access to with a system in order. The progressive thoughts shown in his other book, Eui-Ryung or 醫零, should be considered as his own thoughts only, and it is an overstatement to consider the book of Ma Gwa Hwe Tong to be his tryout in such thoughts.

• 한국산학기술학회논문지
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• 제12권2호
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• pp.565-570
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• 2011

본 연구는 파인 블랭킹(fine blanking) 프레스로부터 기능면으로 사용되는 100% 매끄러운 전단면을 얻는 파인 블랭킹 공정에서 다이 롤(die roll) 크기를 최소화하기 위한 목적으로 실험을 통해 다이 챔퍼(die chamfer) 형상에 따라 성형되는 제품의 다이 롤 크기 변화를 검토한 것이다. 다이 챔퍼가 다른 여러 가지 다이 편(die insert)을 제작하여 파인 블랭킹 실험을 실시한 후 다이 챔퍼 형상에 따른 다이 롤 크기를 측정 분석하여 두께 방향 다이 롤 크기의 경향을 파악하였다. 이 연구 결과는 파인 블랭킹 판재 성형에서 두께 방향 다이 롤 크기를 최소화하기 위한 다이챔퍼 설계에 유용하게 적용될 것으로 판단된다.

• 한국실내디자인학회논문집
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• 제19권1호
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• pp.169-179
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• 2010

Since modernization period thru Japanese colonial era the modern architect began to play a important role for Korean housing architecture. So called 'House as an Art Work', detached houses by prominent architects, belong to a meaningful sector in Korean modern housing architecture. The harmony with tradition was always big issue for such works. This study aims to understand how paradigms for tradition were interpreted with the changes of the time. The analysis showed various tryout by architects, that concretize traditional characteristics in their work. For example, traditional lifestyle were clearly reflected in the floorplan during 30's and 40's. In the 70's building mass and formative roof design were emphasized to present traditional image. As well as it represented primitive esthetic and vernacular decoration. In addition, expressive tendency, that demonstrates korean sentiment through material and its texture, got a preference. Since latter half of 80's some traditional architectural elements were modernized and space characteristics were newly created from acculturation. Furthermore the philosophy of "Subdivision of building wings and Emptiness" follows this trend. This type made a courtyard and connected articulated building masses each other. "Sympathy with Nature" were most essential for a traditional houses in contrast with western architecture. Many architects today make various method to bring nature into interior space and to contemplate nature In the house. Such kinds of adaptation to tradition could be understood as a unique process to manifest identity of Korean modern houses.

• 소성∙가공
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• 제21권1호
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• pp.36-41
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• 2012

Gas Assisted Injection Molding is a relatively new low-pressure injection molding technique that provides benefits such as reduced part warpage, excellent surface quality without shrink marks, greater design flexibility, etc. In the gas assisted injection molding process, the injected pressurized nitrogen gas flows through designed gas channels and forms hollow sections within the part. However, due to the characteristics of the gas, the design of the gas channels which are the paths for the injected gas is important in order to avoid defects such as gas blowout, fingering, etc. Therefore, in this study, the gas channel design for gas assisted injection molding of exterior display panels was conducted by examining the results of three CAE analyses. The designed gas channel was verified by conducting tryouts using a 450 ton injection molding machine with 3-stage pressure controlled gas kit. In addition, the hollow shapes which were formed by the gas with the installed gas channels were examined by examining the cross sections of the prototypes that were produced. As a result, it was found that exterior display panels can be produced without any defect by applying the gas assisted injection molding technique.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.285-288
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• 2007

The use of commercial finite element analysis software to perform the entire process analysis and springback analysis has increased fast for last decade. Pamstamp2G is one of commercial software to be used widely in the world but it has still not been perfected in the springback prediction accuracy. We must select the combination of input parameters for the highest springback prediction accuracy in Pamstamp2G because springback prediction accuracy is sensitive to input parameters. Then we study the affect of input parameters to use member part for acquiring high springback prediction accuracy in Pamstamp2G. First, we choose important four parameters which are adaptive mesh level at drawing stage and cam flange stage, Gauss integration point number through the thickness and cam offset on basis of experiment. Second, we make a orthogonal array table L82[(7)] which is consist of 8 cases to be combined 4 input parameters, compare to tryout result and select main factors after analyzing affect factors of input parameters by Taguchi's method in 6 sigma. Third, we simulate after changing more detail the conditions of parameters to have big affect. At last, we find the best combination of input parameters for the highest springback prediction accuracy in Pamstamp2G. The results of the study provide the selection of input parameters to Pamstamp2G users who want to Increase the springback prediction accuracy.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 제5회 박판성형 SYMPOSIUM
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• pp.55-60
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• 2006

Draw-bead is applied to control the material flow in a stamping process and improve the product quality by controlling the draw-bead restraining force (DBRF). Actual die design depends mostly on the trial-and-error method without calculating the optimum DBRF. Die design with the predicted value of DBRF can be utilized at the tryout stage effectively reducing the cost of the product development. For the prediction of DBRF, a simulation-based prediction model of the circular draw-bead is developed using the Box-Behnken design with selected shape parameters such as the bead height, the shoulder radius and the sheet thickness. The value of DBRF obtained from each design case by analysis is approximated by a second order regression equation. This equation can be utilized to the calculation of the restraining force and the determination of the draw-bead shape as a prediction model. For the evaluation of the prediction model, the optimum design of DBRF in sheet metal forming is carried out using response surface methodology. The suitable type of the draw-bead is suggested based on the optimum values of DBRF. The prediction model of the circular draw-bead proposes the design method of the draw-bead shape. The present procedure provides a guideline in the tool design stage for sheet metal forming to reduce the cost of the product development.

• 한국융합학회논문지
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• 제3권4호
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• pp.29-34
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• 2012

자동차는 2만 여개가 넘는 부품들로 구성되어 있다. 또한, 새시와 함께 자동차 내부에는 조향장치, 파워장치, 도어 록 장치 등 많은 전기 전자 및 센서들이 부가되어 수송 외 운전자가 주행 중 운전을 용이하게 수행할 수 있는 여러 가지 장치들이 별도로 차체내부 혹은 외부에 부착되어 있다. 그 가운데 자동차의 도어 유리 부위는 제작 초기에는 운전자가 직접 휠을 회전시켜 유리문을 상하로 개폐하였으나 최근 들어 모터, 센서, 스위치 류 등의 발달로 버튼하나로 문을 상하로 개폐시키는 방법을 사용하게 되었다. 유리문을 상하로 개폐시키는 조립부위를 자동차에서는 power window motor assembly라고 이를 개발하는 것이 본 연구의 목적이다. 현재는 anti-pinch type power window motor에 ECU(Electronic Control Unit) system이 국내에서 개발되지 못하고 있다. 뿐만 아니라, 이 연구에서는 CAE 해석과 개발을 통해 anti-pinch power motor gear housing 및 cylindrical gear를 국산화 개발하고 ECU 일체형 적용을 함으로 인해 조립공정의 단순화 및 원가절감에 기여하고자 한다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.106-109
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• 2005

Springback is a common phenomenon in sheet metal forming, caused by the elastic recovery of the internal stresses after removal of the tooling. Recently, advanced high strength steels (AHSS) such as TRIP and DP are finding acceptance in the automotive industry because their superior strength to weight ratio can lead to improved fuel efficiency and assessed crashworthiness of vehicles. The major troubles of the automotive structural members stamped with high strength steel sheets are the tendency of the large amount of springback due to the high yield strength and the tensile strength. The amount of springback is mainly influenced by the type of the yield function and anisotropic model induced by rolling. The discrepancy of the deep drawn product comparing the data of from the product design induced by springback must be compensated at the tool design stage in order to guarantee its function and assembly with other parts. The methodology of compensation of the low shape accuracy induced by large amount of springback is developed by the expert engineer in the industry. Recently, the numerical analysis is introduced in order to predict the amount of springback and to improve the shape accuracy prior to tryout stage of press working. In this paper, the tendency of springback is evaluated with respect to the blank material. The stamping process is analyzed fur the front side member formed with AHSS sheets such as TRIP60 and DP60. The analysis procedure fully covers the binderwrap, stamping, trimming and springback process with the commercial elasto-plastic finite element code LS-DYNA3D.