• Journal of information and communication convergence engineering
• /
• 제16권1호
• /
• pp.43-47
• /
• 2018

The existing modeling of avalanche dominated breakdown in double gate MOSFETs (DGMOSFETs) is not relevant for 10 nm gate lengths, because the avalanche mechanism does not occur when the channel length approaches the carrier scattering length. This paper focuses on the punch through mechanism to analyze the breakdown characteristics in 10 nm DGMOSFETs. The analysis is based on an analytical model for the thermionic-emission and tunneling currents, which is based on two-dimensional distributions of the electric potential, obtained from the Poisson equation, and the Wentzel-Kramers-Brillouin (WKB) approximation for the tunneling probability. The analysis shows that corresponding flat-band-voltage for fixed threshold voltage has a significant impact on the breakdown voltage. To investigate ambiguousness of number of dopants in channel, we compared breakdown voltages of high doping and undoped DGMOSFET and show undoped DGMOSFET is more realistic due to simple flat-band-voltage shift. Given that the flat-band-voltage is a process dependent parameter, the new model can be used to quantify the impact of process-parameter fluctuations on the breakdown voltage.

• 대한기계학회논문집
• /
• 제17권2호
• /
• pp.285-299
• /
• 1993

본 연구에서는 UBET를 이용한 프로그램을 개발하여 소성가공 문제에 적용하였 으며, 형단조 가공에서 형 내부의 재료의 비정상 유동을 해석할 수 있는 알고리듬을 제시하였다. 매 변형단계에서 요소별 가공경화를 고려하여 자동적으로 요소시스템 (element system)을 재구성함으로써, UBET에 의한 소성가공 문제 해석을 효율적으로 할 수 있도록 하였다. 축대칭 형단조 문제에 있어서 리브의 높이대 폭의 비가 1.0, 2.0일때 UBET 및 탄소성 유한요소법에 의하여 형 내부의 재료 층만 과정을 시뮬레이션 하였으며, 단조 하중, 다이 충만도 및 재료의 유동 경향을 분석하여 적절한 유동 모델 과 초기 소재의 형상을 구하였다. 모델 재료를 사용한 형단조 모의실험을 수행하여 재료유동 및 변형 단계별 단조 하중분포 등을 구하였으며, 해석결과와 비교 분석하였 다. 또한 후방압출(backward extrusion) 및 평두형 펀치에 의한 평판압입(flat pu- nch indentation) 문제를 해석하였다. 후방압출시 모서리부의 라운딩(rounding) 효 과가 재료 유동에 미치는 영향을 고려하였으며, 평두형 펀치에 의한 평판압입에서는 상당 소성변형률(equivalent plastic strain)의 분포를 탄소성 유한요소법(elastic plastic finite element method)에 의한 결과와 비교하였다.

• 한국정밀공학회지
• /
• 제15권6호
• /
• pp.22-32
• /
• 1998

This paper describes a research work of developing a computer-aided design of irregularly shaped-sheet metal product with bending and piercing operation for progressive working. An approach to the CAD system is based on the knowledge-based rules. Knowledge for the CAD system is formulated from plasticity theories, experimental results and the empirical knowledge of field experts. The system has been written in AutoLISP on the AutoCAD with a personal computer and is composed of five main modules, which are input and shape treatment, flat pattern-layout, production feasibility check, blank-layout, and strip-layout module. Based on knowledge-based rules, the system is designed by considering several factors, such as radius and angle of bend, material and thickness of product, complexities of blank geometry and punch profile, and availability of press. This system is capable of unfolding a formed sheet metal part to give flat pattern and automatically account for the adjustment of bend allowances to match tooling requirements by checking dimensions and the best utilization ratio of blank-layout within bending production feasibility area which is beyond ${\pm}30^{\circ}$ degrees intersecting angle between grain flow and bending edge line and which is suitable to progressive bending operation. Also the strip-layout drawing generated by a bending and a piercing operation according to punch profiles divided into automatically for external area of irregularly shaped-sheet metal product is displayed in graphic forms.

• 오토저널
• /
• 제7권3호
• /
• pp.42-55
• /
• 1985

The study is concerned with the investigation of curved line folding of developable surface from flat sheets of metal. General geometric relations among folding line, folded surface, folded angle are derived. From the derived geometric relations, the required plastic work and punch force are derived for the first approximation. Five methods of forming are suggested and the experiment is carried out using two chosen methods for the prismatic developable surfaces of which cross-sections have 103.deg.arc, 180.deg.arc, sinusoidal shape. In the die design for the tolding of prismatic developable surfaces, a stack of sheets were used to form shapes of the dies by which acceptable folded surfaces were obtained. The computed plastic work and punch force turned out to be in reasonable agreement with the experimental result.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 1994년도 추계학술대회 논문집
• /
• pp.80-94
• /
• 1994

As for axisymmetirc sheet metal forming, a kind of pick-up apparatus for body-wrinkling is deviced. Experiments with both hemispherical and flat headed punches, with various clearances between punch and die, with respect to three kinds of materials each of which has two thicknesses, are performed. Firstly the process of evolution of body-wrinkling is observed. Then the critical blank-holding force (or meridional tensile force) for suppression of body-wrinkling at a specified punch-stroke is measured for all cases mentioned above. An empirical formula for it is proposed. Deformation patterns and stress distributions are analysed by the use of FEM. A simplified critical condition for body-wrinkling is formulated and introduced into the FEM program. And its effectiveness is checked by comparison with the experimental results. Using this FEM system, the governing factors of body-wrinkling are cleared up.

• 소성∙가공
• /
• 제5권2호
• /
• pp.97-104
• /
• 1996

It is very important to obtain the knowledge of loads and flow patterns in most processes because these information are the fundamental data of die design and process design. The objective of present study is to investigate loads and metal flow patterns for various process conditions in flat die extrusion of square-bars from circular billets. For analyzing the metal flow patterns of the billets photo etching is used on sections of split specimen. From this method metal flow patterns are analyzed for various area reductions friction factors and punch stroke through the process from initial-stage to final-stage. Experiments are carried out with hard solder billets at room temperature.

• 소성∙가공
• /
• 제7권3호
• /
• pp.246-259
• /
• 1998

This paper describes a research work of developing a computer-aided design and manufacturing of irregular shaped sheet metal product for blanking or piercing and bending operations. An approach to the system is based on the knowledge-based rules. Knowledge for the system is formulated from plasticity theories experimental results and the empirical knowledge of field experts, This system has been written in AutoLISp on the AutoCAD and in customer tool kit on the SmartCAM with a personal computer and is composed of nine modules which are input and shape treatment, flat pattern-layout, pro-processor module. Based on the knowledge-based rules, the system is designed by considering several factors, such as material and thickness of product complexities of blank geometry and punch profile sheet metal to give flat pattern and automatically account for the adjustment of bending allowances to match tooling requirements by checking dimensions and generating NC data automatically according to drawings of die-layout module. Results carried out in each module will provide efficiencies to the designer and the manufacturer of blanking or piercing and bending die in this field.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2000년도 추계학술대회 논문집
• /
• pp.591-594
• /
• 2000

This paper describes a research work of developing a computer-aided design of product with bending and piercing for progressive working. An approach to the system for progressive working is based on the knowledge-based rules. Knowledge for the system is formulated from plasticity theories, experimental results and the empirical knowledge of field experts. The system has been written in AutoLISP on the AutoCAD with a personal computer and is composed of four main modules, which are input and shape treatment, flat pattern layout, strip layout and die layout module. Based on knowledge-based rules, the system is designed by considering several factors such as radius and angle of bend, material and thickness of product, complexities of blank geometry and punch profile, bending sequence, and availability of press. Strip layout drawing generated by the piercing processes with punch profiles divided into for external area is simulated in 3-D graphic forms, including bending sequences for the product with piercing and bending. Results obtained using the modules enable the manufacturer for progressive working of electronic products to be more efficient in this field.

• 한국정밀공학회지
• /
• 제19권1호
• /
• pp.79-92
• /
• 2002

This paper describes a research work of developing computer-aided design of a product with bending and piercing for progressive working. An approach to the system for progressive working is based on the knowledge-based rules. Knowledge for the system is formulated from plasticity theories, experimental results and the empirical knowledge of field experts. The system has been written in AutoLISP on the AutoCAD with a personal computer and is composed of four main modules, which are input and shape treatment, flat pattern layout, strip layout and die layout modules. The system is designed by considering several factors, such as bending sequences by fuzzy set theory, complexities of blank geometry, punch profiles, and the availability of a press equipment. Strip layout drawing generated in the strip layout module is presented in 3-D graphic farms, including bending sequences and piercing processes with punch profiles divided into for external area. The die layout module carries out die design for each process obtained from the results of the strip layout. Results obtained using the modules enable the manufacturer for progressive working of electric products to be more efficient in this field.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2016년도 춘계학술대회
• /
• pp.367-370
• /
• 2016

QFN(Quad Flat No-leads package)은 SMD(Surface Mount Device) 자재 중의 하나로써, 납땜을 하는 lead 부분이 따로 있지 않아 납땜에 대한 불량이 많이 발생하고 있다. 따라서 본 논문에서는 QFN의 납땜에 대한 불량을 검출하는 기법을 제안하고자 한다. 우리는 QFN의 납땜에 대한 불량 검출을 위해 기계학습 방법 중 하나인 Convolutional Neural Network(CNN)을 사용하였고, CNN에 학습을 시키기 위한 데이터로는 납땜을 한 QFN 컬러 다단 영상을 사용하였다. 이 영상은 3채널 컬러 영상으로, 이를 바로 CNN에 적용시켜 학습시키기에는 문제가 있다. 그렇기 때문에 3채널 컬러 영상을 세개의 1채널 Grayscale 영상(Red, Green, Blue)로 분리시켜 CNN에 적용시켰다. 이렇게 학습시킨 결과를 이용하여 QFN의 납땜에 대한 불량을 검출할 수 있었다. 현재는 Dicing과 Punch에 대해서만 테스트를 해보았기 때문에, 추후에 이를 제외한 다른 것들에 대한 추가적인 연구가 필요하다.