• 마이크로전자및패키징학회지
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• 제23권2호
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• pp.79-84
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• 2016

유연전자소자가 외부힘에 의해 변형될 경우 반도체 다이가 기계적 응력 때문에 변형되거나 파괴되고 이러한 변형이나 파괴는 channel의 전자이동도를 변화시키거나 배선의 저항을 증가시켜 집적회로의 동작 오류를 발생시킨다. 따라서 반도체 집적회로는 굽힘 변형이 발생해도 기계적 응력이 발생하지 않는 중립축에 위치하는 것이 바람직하다. 본 연구에서는 굽힘변형을 하는 flip-chip 접합공정이 적용된 face-down flexible packaging system에서 중립축의 위치와 파괴 모드를 조사하였고 반도체 집적회로와 집중응력이 발생한 곳의 응력을 감소시킬 수 있는 방법을 제시하였다. 이를 위해, 설계인자로 유연기판의 두께 및 소재, 반도체 다이의 두께를 고려하였고 설계인자가 중립축의 위치에 미치는 영향을 조사한 결과 유연기판의 두께가 중립축의 위치를 조절하는데 유용한 설계인자임을 알 수 있었다. 3차원 모델을 이용한 유한요소해석 결과 반도체 다이와 유연기판 사이의 Cu bump 접합부에서 항복응력보다 높은 응력이 인가될 수 있음을 확인하였다. 마지막으로 flexible face-down packaging system에서 반도체 다이와 Cu bump 의 응력을 감소시킬 수 있는 설계 방법을 제안하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.302-305
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• 2007

The springback characteristics of AZ31B magnesium alloy sheet was investigated in OSU draw/bend test. Springback is the elastically-driven change of shape of a part after forming and it should be estimated and controlled to manufacture more precise products in sheet forming. The demands are increasing for magnesium alloy sheet press forming, but the study on its springback characteristics is insufficient. Strip draw/bend tests were conducted with various conditions - die radius, sheet thickness and controlled tensile force. The springback angles were measured from 'sidewall curl' of deformed shape. The tendency of springback angle was observed from the tests.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.155-159
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• 2007

We conduct intelligent simulation of three-dimensional forging processes in this paper. A new remeshing technique is employed for this purpose. Not only the state variables including strain and strain-rate but also the geometrical features including die-material contact conditions and the characteristic lines or surfaces are taken into account during remeshing. The presented approach is applied to the Baden-Baden benchmark test example and its influence on the simulated results is discussed particularly in terms of the deformed shape with emphasis on the characteristic line.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.35-43
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• 2001

As the demands for lightweight construction and precision grow, there is an increasing interest on hydroforming technology. This paper deals with designing automobile subframe for applying welded blanks hydroforming. In applying welded blanks hydroforming to automobile subframe, it is a serious problem that blanks wrinkle in deformed shape. To suppress wrinklings in blanks, the sections of the die where blanks wrinkled is modified. In addition to this, it is intended that the sum of thickness variation about wrinkling regions be minimized. For this purpose, parameters for influencing formability are selected and evaluated using orthogonal array. Among these parameters, parameters having a major effect on formability are selected again. Using CCD(central composite design) with the selected parameters, response surface is build up and optimal design is performed.

• 소성∙가공
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• 제7권5호
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• pp.445-449
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• 1998

In order to obtain optimum process variables during the drawing of stainless steel sheets rectangular cup drawing tests were carried out with several technically available stainless steel sheets. As parameters on testing materials for die and punches lubrication and blank holding forces were selected. Testing parameters played an important role if the deformed material was thin. Effect of material properties on the deformation behaviors was also discussed by using testing parameters selected in this experiment. From the test results we suggest the appropriate conditions to be applicable to the actual manufacturing processes

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.286-290
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• 2003

Accurate acquisition of surface geometries such as machined surfaces, biological surfaces, and deformed parts have been very important technique in scientific study and engineering, expecially for system design, manufacturing and inspection. Two camera method keeps accuracy more than double than mechanical method. In this paper, we describe the processes surface data of teeth for automatic processing, transformation that changes to coping data of possible numeric data form and processed inlay teeth. As the result of the Inlay manufacture, which can process with high resolution, therefore we construct the automatic processing system that depends on manual

• 대한기계학회논문집A
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• 제22권3호
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• pp.493-503
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• 1998

The sectional forming analysis considering bending effects from the geometrically deformed shape of two linear membrane finite elements(called super element) was performed under plane strain assumption for analyzing forming processes of an arbitrarily shaped draw-die. For the evaluation of bending effects, the bending equivalent forces are calculated from the bending moment computed using the changes in the interior angle at the middle node of super element, and are agumented to the membrane stretch forces. In order to verify the validity of the bending formulation, the simulation results for the stretch, draw, and bend sections were compared with membrane analysis results and measurements.

• 대한기계학회논문집
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• 제11권1호
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• pp.110-117
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• 1987

본 논문에서는 터어빈과 콤프레셔 블레이드의 정밀예비현상 및 캠 부품의 제 조에 사용되는 원형소재로부터의 타원형재의 압출에 대한 일반적인 해석방법을 제안할 것이다. 해석결과는 실제 가공경화재인 알루미늄합금(Al2024)의 압출실험을 수행하 여 타당성을 검토하도록 할 것이며 기존의 해석 및 실험결과와도 비교 논의하도록 하 겠다.

• 대한기계학회논문집
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• 제16권7호
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• pp.1314-1321
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• 1992

본 연구에서는 중실형의 해석을 확장하고 유선함수와 상계해법을 이용하여 일 반적 경계역을 갖는 관형압출의 체계적 해석법을 연구해서 보다 정확한 압출하중의 예 측 뿐아니라 소성변형역 및 소성유동도 예측 가능한 방법을 제안하고자 한다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.258-261
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• 2003

In this study, finite element analysis for multi-stage deep drawing process of rectangular configuration with extreme aspect ratio is carried out especially for the blank design. The analysis of rectangular deep drawing process with extreme aspect ratio is likewise very difficult with respect to the design process parameters including the intermediate die profile. In order to solve the difficulties, numerical approach using finite element method is performed in the present analysis and design. A series of experiments for multi-stage rectangular deep drawing process are conducted and the deformed configuration is investigated by comparing with the results of the finite element analysis. Additionally, to minimize amount of removal material after trimming process, finite element simulation is applied for the blank modification. The analysis incorporates brick elements for a rigid-plastic finite element method with an explicit time integration scheme using LS-DYNA3D.