• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 추계학술대회 논문집
• /
• pp.993-996
• /
• 2005

This paper is concerned with transfer process on hot forging of bearing hub. Workers on hot forging have difficulty in working by high temperature and weight workpiece. And In conventional got forging of bearing hub, the material wasted to the flash accounts approximately 10% of the original workpiece. It is need manufacture automation and reduce the cost of forged products. Surface treatment of die and lubricant are investigated from experiment and FE-simulation for analysis of forming simulation. In order to hot forging process design considered flash thickness and blocker geometry and initial temperature of die and billet. This transfer process gave comparatively good results compared with actual products.

• 한국정밀공학회지
• /
• 제12권12호
• /
• pp.91-99
• /
• 1995

An effort has been made to more accurately analyze the flow in the chip cavity, particularly to model the flow through the openings in the leadframe and correctly treat the thermal boundary condition at the leadframe. The theoretical analysis of the flow has been done by using the Hele- Shaw approximation in each cavity separated by a leadframe. The cross-flow through the openings in the leadframe has been incorporated into the Hele-Shaw formulation as a mass source term. The temperature of the leadframe has been calculated based on energy balance in the leadframe. The flow behavior in the leadframe has been verified experimentally. In the experiment, a transparent mold and clear fluid have been used for flow visualization. Comparisons were made between the calculation and experimental results which showed a good agreement.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2013년도 춘계학술대회 논문집
• /
• pp.953-954
• /
• 2013

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2010년도 제39회 하계학술대회 초록집
• /
• pp.206-206
• /
• 2010

1차원 나노 소재 중 ZnO 나노선은 우수한 전기적, 광학적 특성으로 최근 센서, 디스플레이등 다양한 정보전자 소자에 활용 가능성이 높아지고 있다. 현재 보고된 ZnO 나노선 소자는 주로 단일선이나 랜덤 네트워크 형태로 제작되어 소자의 공정성, 재현성 및 균일성 확보가 매우 중요한 이슈가 된다. 본 연구에서는 화학기상증착법으로 성장한 ZnO 나노선을 슬라이딩 트랜스퍼 공정을 통하여 원하는 기판에 정렬된 형태로 전이하여 전계방출소자 (field effect transistor) 어레이를 제작하고 그 특성을 분석하였다. 또한, p-형으로 도핑된 Si 기판을 패터닝하여 정렬된 ZnO 나노선과 pn-정션 소자를 제작하여 정류특성과 electroluminescence 특성을 분석, 설명하였다.

• 한국전기전자재료학회논문지
• /
• 제30권9호
• /
• pp.572-576
• /
• 2017

A hybrid transparent electrode was fabricated with graphene and silver nanowires (Ag NWs). Three different processes were used to fabricate the hybrid electrode. Measurements of the sheet resistances, transmittances, and surface roughnesses of the hybrid electrodes were used to identify the optimal fabrication process. The surface roughness of the hybrid electrodes with Ag NWs embedded in a transparent polymer matrix was significantly lower than that of the other hybrid electrodes. A hybrid electrode fabricated by transferring graphene onto Ag NWs after spin-coating the Ag NWs onto the substrate showed the lowest sheet resistance. The transmittance of the hybrid electrodes was comparable to that of Ag NW electrodes.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2010년도 제39회 하계학술대회 초록집
• /
• pp.269-269
• /
• 2010

$SnO_2$ 나노선은 n-type의 전기적 특성과 우수한 광 특성을 보이며, 전자소자, 광소자 뿐 아니라 다양한 종류의 가스 센서 등에 응용되고 있다. 그러나 $SnO_2$ 나노선은 공기중에서 전기적으로 불안정한 특성을 보이며, 도핑을 하지 않은 나노선 소자에서는 전자의 모빌러티가 높지 않다는 단점을 갖고 있다. 이를 개선하고자 본 연구에서는 화학기상증착법 (Chemical Vapor Deposition)으로 Sb을 도핑한 $SnO_2$ 나노선을 성장하여 전계방출효과 트랜지스터 (field effect transistor: FET)를 제작하여 전기적 특성과 UV 반응성의 변화를 측정하였다. Sb 도핑 양을 늘려감에 따라 전기적 특성이 반도체 특성에서 점점 금속 특성으로 변하는 것과 게이트 전압의 영향을 적게 받는 것을 확인하였다. 또한 도핑을 해준 $SnO_2$ 나노선의 경우 UV 반응과 회복 시간이 기존에 비하여 크게 감소하여 UV 센서에 더욱 적합해진 것을 확인하였다. 또한, 슬라이딩 트랜스퍼 공정을 이용하여 나노선을 원하는 기판에 정렬된 상태로 전이할 때 도핑한 나노선은 표면특성의 변화로 정렬도가 크게 감소하는 것을 확인하였고, 기판에 윤활제를 사용하여 정렬도를 높일 수 있었다.

• 한국CDE학회논문집
• /
• 제5권3호
• /
• pp.255-262
• /
• 2000

A computer-aided process planning (CAPP) system for rotationally symmetric deep drawing products has been developed. The application for non-axisymmetric components, however, has not been reported yet. Therefore, this study investigates process sequence design in deep drawing process and constructs an expert system of process planning for non-axisymmetric motor frame products with elliptical shape. The system developed consists of four modules. The first one is recognition of shape module to recognize the products. The second one is a 3-D modeling module to calculate surface area for non-axisymmetric products. The third one is a blank design module that creates an oval-shaped blank with the identical surface area. The forth one is a process planning module based on production rules that play the best important role in an expert system for manufacturing. The production rules are generated and upgraded by interviewing with field engineers. The constructed system using AutoLISP language under the AutoCAD environment is baled on the knowledge base system which is involved a lot of expert's technology. Results of this system will be provide effective aids to the designer and engineer in this field.

• 한국CDE학회논문집
• /
• 제7권1호
• /
• pp.9-17
• /
• 2002

The study is insufficient on process planning of the elliptical deep drawing product. Thus, in this present study, the expert system for elliptical deep drawing products was constructed by using process sequence design. The expert system was developed to be based on the general concept of each entity. The system was developed in this work consists of sixth modules. The first one is a shape recognition module to recognize non-axisymmetric products and to generate Entity_list. The second one is three dimensional (3-D) modeling module to calculate the surface area for non-axisymmetric products. The third one is a blank design module to create suggested blanks of three shapes with the identical surface area. The fourth one is shape design module based on the production rules that play the most important role in an expert system for manufacturing. The production rules are generated and upgraded by inter- viewing field engineers, plastic theory and experiments. The fifth and sixth ones are a graphic module to visualize results of the expert system and a post module to rise user's convenience, respectively. According to constructed the expert system for process sequence design, it was possible to reduce the lead time.

• 한국생산제조학회지
• /
• 제23권5호
• /
• pp.413-420
• /
• 2014

Although the transfer forming process has various advantages, it is also inefficient for the use of multiple press machines, especially for small part sizes. In this study, a new forming process was proposed to use multiple tandem dies in a single press machine. A rotary transfer forming device was developed to combine the advantages of the progressive and transfer forming process. In this study, a detailed forming process using this device was analyzed, and the device was designed to perform four series of tandem forming processes in a single press. In order to analyze the feasibility of this forming process, simple forming dies were made. As a result, the position accuracy was 4 arcsec, and the forming speed reached up to 20 strokes per minute. It is thought that this rotary transfer forming device can help to save initial setup costs through the more efficient use of space in a press machine.

• 한국산학기술학회논문지
• /
• 제18권3호
• /
• pp.49-55
• /
• 2017

대부분의 모터 케이스는 방수기능과동심도, 직각도 품질 등이 우수한딥드로잉 제품을 채택하고 있으며 그외 방수기능이 필요없는 블로우모터, 시트모터 등 실내에 장착되는 모터 케이스는 멀티포밍 제조방법을 채택하고 있다. 딥드로잉 공정은 드로잉 성형, 트리밍 및 피어싱 등 약 12공정을 소화할수 있는 고가의 트랜스퍼 프레스가 필요하다. 하지만 멀티포밍 공법은 멀티포밍기 1대 또는 멀티포밍기 1대와 프레스 1대의 구성으로 이루어지기 때문에 저렴한 투자로도 완제품 생산이 가능하다. 멀티포밍기는 대부분 수입이 되는 고가설비 이고 국내 중소기업이 개발한 굽힘/전단가공 일체형 멀티포밍기는 생산원가를 줄이는데 부족하여 굽힘/전단 분리형 멀티포밍기를 본 연구를 통해 개발하였다. 일체형 멀티포밍기는 비교적 얇고 작은소형 제품을 제한적인 작업 방법으로 사용된다. 크고 소재가 두꺼운 제품은 전단 하중이 높아 단발 크랭크 프레스를 이용하고 블랭킹 후 멀티포밍기로 이동 작업자가 수작업으로 소재를 공급한다. 멀티포밍기에서 벤딩 작업이 이루어지면 다시 프레스로 이송해 치수를 교정한다. 이러한 작업공정 분산은 생산성 저하, 품질이슈 및 과도한 인원 투입으로 원가경쟁력 저하를 가져왔다 이에 굽힘/전단가공 공정분리와 설비자동화를 통하여 안정되고 원가가 절감되는 생산체계를 갖추고자 하는게 본 연구의 목적이다.