• 소성∙가공
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• 제26권2호
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• pp.95-100
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• 2017

In this study, the method of process design for side forming of a tooth part used for a component of automobile transmission was suggested using FE-simulations. To develop the side forming for the tooth part, in this paper, the shape factors of B.T.Pin was considered as design parameters. The shape factors of B.T.Pin were selected to be the round of pin, reinforced angle and reinforced length. Based on FE simulation results, appropriate shape factor without causing any defects was selected. In addition, to increase the strength of pin, the combination of shape factor having minimum stress after side forming was selected using FE-simulation. In addition, with design of a die set, cold side forming of the tooth part was experimented to estimate effectiveness of the designed B.T.Pin. From experiments, it was found that the tooth part with complete formation of the tooth was obtained without making any forming defects and punch fracture.

• 전기학회논문지
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• 제60권7호
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• pp.1434-1437
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• 2011

Precision measurement of silicon wafer resistivity has been using single-configuration Four-Point Probe(FPP) method. This FPP method have to applying sample size, shape and thickness correction factor for a probe pin spacing to precision measurement of silicon wafer. The deference for resistivity measurement values applied correction factor and not applied correction factor was about 1.0 % deviation. The sample size, shape and thickness correction factor for a probe pin spacing have an effects on precision measurement for resistivity of silicon wafer.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 학술대회
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• pp.229-232
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• 2008

This study presents a numerical procedure to optimize the shape of stepped circular pin-fins to enhance turbulent heat transfer. The KRG method is used as an optimization technique with Reynolds-averaged Navier-Stokes analysis of fluid flow and heat transfer with shear stress transport turbulent model. The objective function is defined as a linear combination of heat transfer and friction loss related terms with a weighting factor. Ten training points are obtained by Latin Hypercube Sampling for two design variables. Optimum shape has been successfully obtained with the increased objective function.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년 추계학술대회논문집
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• pp.229-232
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• 2008

This study presents a numerical procedure to optimize the shape of stepped circular pin-fins to enhance turbulent heat transfer. The KRG method is used as an optimization technique with Reynolds-averaged Navier-Stokes analysis of fluid flow and heat transfer with shear stress transport turbulent model. The objective function is defined as a linear combination of heat transfer and friction loss related terms with a weighting factor. Ten training points are obtained by Latin Hypercube Sampling for two design variables. Optimum shape has been successfully obtained with the increased objective function.

• 마이크로전자및패키징학회지
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• 제18권2호
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• pp.29-33
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• 2011

솔더와 PCB Cu 패드와 솔더 경계면에서 발생하는 수직응력과 수평응력을 분석하여 PGA 패키지의 신뢰성 향상을 위한 리드핀의 형상설계에 대한 연구를 수행하였다. 이와 같은 연구를 위해 리드핀의 $20^{\circ}$ 각도 굽힘 변형과 50 ${\mu}m$ 인장조건에서 4인자 3수준의 다구찌 최적설계와 유한요소해석을 수행하였다. 해석결과에 의하면 리드핀의 헤드곡면과 PCB Cu 패드가 접촉하는 폭(d2)이 솔더에서 발생하는 응력감소에 가장 큰 영향을 미치는 인자로 계산되었다. 또한, 다 구찌법의 파라메타 설계에 의해 기존 리드핀 형상모델에 비해 약 18.7%의 등가 von Mises 응력이 감소하는 형상을 도출하였다. 한편, 최대 수직응력이 발생하는 위치가 PCB의 Cu 패드와 솔더의 외곽이 접촉하는 위치이고 최대 수평응력이 발생하는 위치가 SR 층과 솔더의 외곽표면이 접촉하는 위치임을 파악하여, PGA 패키지의 박리 불량은 솔더의 외곽부터 발생하여 내부로 진행될 것으로 예측되었다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.443-447
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• 2003

The BEM (Boundary Element Method) is a computational technique for the approximate solution of problems in continuum mechanics. In the BEM both volume and surface integrals transformed into boundary integral equations. So, we applied the ECM (Electrochemical Machining) process to boundary problem, because our focus is only deformed shape. The ECM process is modeled as a two-dimensional problem assuming constant properties of electrolyte, and an incremental formulation is used with automatic mesh regeneration. As a result the final shape is roughly agreed with experimental shape. But, it has an error of exact shape, because a chemically factor is not considered

• 대한기계학회논문집B
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• 제34권7호
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• pp.703-714
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• 2010

본 연구에서는 크리깅 기법을 이용하여 엇갈린 핀휜이 부착된 회전하는 내부냉각유로의 형상 최적화를 수행하였다. 냉각유로 형상의 여러 매개변수 중 핀의 지름과 높이의 비, 핀의 지름과 핀과 핀 사이의 거리의 비를 최적설계를 위한 설계변수로 선택하였다. 열전달 관련 목적함수와 마찰손실 관련 목적함수를 가중계수를 이용하여 선형적으로 결합한 목적함수를 정의하였다. 크리깅 모델을 구축하기 위해 라틴하이퍼큐브 샘플링기법에 의해 생성된 20개 실험점에서 목적함수가 SST난류모델을 사용한 삼차원 레이놀즈평균 나비어-스톡스(RANS) 유동해석법에 의해 계산되었다. 크리깅 기법을 통하여 예측된 목적함수값은 RANS해석을 이용해 계산된 값과 매우 작은 오차 범위 내에서 일치하였으며, 최적설계를 통해 목적함수가 11% 감소하는 결과를 얻었다.

• Nuclear Engineering and Technology
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• 제50권7호
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• pp.1024-1036
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• 2018

In this paper, McCARD code was verified using various models listed in the NUREG/CR-6361 benchmark guide, which provides specifications for single pin-cells, single assemblies, and the whole core classified depending on the nuclear properties and structural characteristics. McCARD code was verified by comparing its results with those of SCALE code for single pin-cell and single assembly benchmark problems. The difference in the multiplication factor obtained through the two codes did not exceed 90 pcm. The benchmark guide treats a total of 173 whole core experiments. The experiments are categorized as simple lattices, separator plates, reflecting walls, reflecting walls and separator plates, burnable absorber fuel rods, water holes, poison rods, and borated moderator. As a result of numerical simulation using McCARD, the mean value of the multiplication factors is 1.00223 and the standard deviation of the multiplication factors is 285 pcm. The difference between the multiplication factors and the experimental value is in the range of -665 pcm to + 1609 pcm. In addition, statistics of results for experiments categorized by reactor shape, additional structure, burnable poison, etc., are detailed in the main text.

• 대한기계학회논문집B
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• 제30권2호
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• pp.95-100
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• 2006

Electrostatic precipitators(EPs) have low pressure drop and high dust collection efficiency and are widely used for industrial dust collectors. The current-voltage characteristics, which are important to maintain high dust collection efficiency, depend on several factor: discharge electrode shape, gas flow property, dust loading etc. In this study, experiments are performed to investigate the current-voltage characteristics of the corona discharge of various electrode geometries and an empirical model is proposed to predict current-voltage characteristics of the corona discharge. The corona onset voltage correction coefficient$(\alpha)$ and the geometry correction coefficient$(k_g)$ are used to the conventional equation for wire-plate type discharge electrode. The corona onset voltages are -6.3kV and almost constant when the numbers of discharge pins are varied from 3 to 9. The length of discharge pins has very sensitive effects on the corona onset voltage. They are increased from -6.3 to -7.8kV when the discharge pin length are 8.5 and 4.5mm, respectively. The empirical model shows good agreement with experimental results and can predict the effects of discharge pin length and number.

• 대한기계학회논문집B
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• 제39권3호
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• pp.245-251
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• 2015

인쇄기판의 양산 신뢰성 확인을 위한 전기검사에서는 다수의 미세 탐침들이 기판의 패드와 접점을 유지하며 회로의 전기적 신뢰성을 확인하는 검사이다. 이 때 다수의 탐침들이 모두 정 정렬 될 수 없으므로 탐침의 충돌하는 위치와 각도는 기판에 심각한 결과를 초래할 수 있다. 본 연구에서는 탐침이 패드와 충돌하는 상황에서 발생할 수 있는 탐침의 미끄러짐 현상을 관측하고자 한다. 탐침은 접촉부가 둥근형상과 평평한 형상의 두 종류를 선정하였고, 탐침 돌출 길이, 탐침 직경, 이송 속도 등이 탐침의 미끄러짐에 주는 영향을 관찰하였다. 이를 통해 전기 검사 시 탐침의 경사에 따라 기판의 패드에 작용하는 수평 인가력과 탐침 경사각 사이의 관계를 조사하였으며, 또 전기 검사 후 미끄러진 탐침의 복원시 발생할 수 있는 탐침과 패드 사이의 역학관계에 대해서도 고찰하였다. 경사각은 탐침의 접촉부가 평평하면서 돌출길이가 짧고, 직경이 크며, 검사 속도가 느린 경우에 작다는 것을 확인하였다.