• 대한핵의학회지
• /
• 제20권2호
• /
• pp.39-45
• /
• 1986

Resting gated blood pool scan was used to derive left ventricular functional changes in normals (N=13, mean age=43) and in patients with coronary artery disease (N=50, mean age=53). Peak filling rates, average filling rates, and ejection fractions were significantly depressed in coronary artery disease. (p<0.0005, each other). And in coronary artery disease with normal ejection fraction (N=21), peak filling rates and average filling rates were depressed also, and peak filling rates of coronary artery disease with normal ejection fraction were abnormal in 61.2% and average fillin rates were abnormal in 71.4%. It appears that (1) resting peak filling rates and average filling rates were sensitive and easily obtainable parameters of the diastolic dysfunction assosiated with coronary artery disease, (2) a significant proportion of coronary artery disease patients without any evidence of abnormal systolic function have depressed resting peak filling rates and average filling rates of the left ventricle.

• 대한기계학회논문집A
• /
• 제27권5호
• /
• pp.657-665
• /
• 2003

Several interesting results were obtained from the flow visualization experiment in the accompanying paper, Part I. in the present study, Part II, a numerical study has been carried out to explain the detailed flow phenomena in micro-channel filling process. Hele-Shaw flow approximation was applied to the micro-channel geometry based on the small characteristic length. And surface tension effect has been introduced on the flow front as the boundary condition with the help of a dynamic contact angle concept between the melt front and the wall. A dimensional analysis for numerical results was carried out and a strong relationship between dimensionless pressure and Capillary number is obtained. The numerical analysis results are compared with the flow visualization experimental observations. And the numerical system developed in the present study seems to be able to predict the interesting micro-channel filling flow characteristics observed from experiments.

• Journal of Electrical Engineering and Technology
• /
• 제9권3호
• /
• pp.843-847
• /
• 2014

In Super Junction (SJ) MOSFETs, charge balance is the most important issue of the SJ fabrication process. In order to achieve the best electrical characteristics, such as breakdown voltage and on-resistance, the N-type and P-type drift regions must be fully depleted when the drain bias approaches the breakdown voltage, which is known as the charge balance condition. In conventional charge balance analysis, based on multi-epi process SJ MOSFETs, analytical model has only N, P pillar width and doping concentration parameter. But applying a conventional charge balance principle to trench filling process, easier than Multi-epi process, is impossible due to the missing of the trench angle parameter. To achieve much more superior characteristics of on-resistance in trench filling SJ MOFET, the appropriate trench angle is necessary. So in this paper, modulated charge balance analysis is proposed, in which a trench angle parameter is added. The proposed method is validated using the TCAD simulation tool.

• Restorative Dentistry and Endodontics
• /
• 제12권1호
• /
• pp.149-153
• /
• 1986

Clinical analysis on early evidence of the pulp response to composite resin filling (27 cases) was made and reached to the results as follow; 1. Under age 40's early symptome was reported within the 1st, 2nd, 3rd and 4th week after composite filling evenly and age 50's reported after 4th week. 2. Sensitive response to cold were 11 cases, to warm 3 cases and to both (cold, warm) were 9 cases. 3. Tenderness to percussion and light pressure on apical area were 5 cases.

• 한국산학기술학회논문지
• /
• 제15권4호
• /
• pp.1838-1843
• /
• 2014

나노 임프린트 리소그래피는 수십 나노미터에서 수십 마이크론에 이르는 패턴을 간단하고 저비용으로 대면적 기판에 제작할 수 있어 차세대 패터닝 기술로 주목 받고 있다. 특히, 발광소자, 태양전지, 디스플레이 등의 분야에서는 저반사 나노패턴, 광결정 패턴 등 기능성 패턴을 제작하고 이를 적용하는 연구가 활발히 진행 중에 있다. NIL공정을 통해 성공적으로 패턴을 전사시키기 위해서는 적절한 공정조건의 선택이 필요하다. 이에 본 연구에서는 열 나노임프린트를 이용하여 모스아이 패턴을 전사할 때, 충전과정 및 잔류층 형성을 수치 해석하여 폴리머 레지스트의 점탄성 거동을 살펴 보았고, 레지스트 초기 코팅 두께의 변화 및 가압력의 변화가 충전과정 및 잔류층에 미치는 영향을 조사하였다. 해석결과 본 논문에서 고려된 PMMA의 경우, 4MPa 이상의 압력에서 100초 내로 충전공정이 완료되는 것으로 나타났다.

• 한국산학기술학회논문지
• /
• 제16권4호
• /
• pp.2364-2369
• /
• 2015

본 논문에서는 고정밀 로터용 원심주조기 방식을 연구 및 개발함으로써 관련 업종의 생산성 향상을 위하여 로터의 충진율 해석을 통해 RPM에 따른 로터의 충진율을 비교해 최적의 RPM을 제시하였다. 회전속도가 600 rpm일 때 충진율 99.47%를 보여줌으로써 실제 작업현장에서의 결과와 비슷하므로 이를 토대로 추가적으로 수행하여 그 결과를 이용한다면 보다 정확한 공정설계를 할 수 있을 것으로 사료된다. 또한 소형 레이들의 전도율해석을 통하여 고품질의 주조제품이 생산될 수 있도록 적합한 소형 레이들의 온도를 분석하였다. 니크롬선을 이용한 가열장치가 없는 경우는 $427^{\circ}C$까지 급격히 떨어진 상태로 알루미늄용액이 급격히 굳어지기 시작했다. 그러나 니크롬선의 가열장치가 있는 경우에는 알루미늄 용액의 용융온도인 $660^{\circ}C$이상을 유지한 상태에서 작업을 할 수 있었으며 온도변화가 거의 없음을 알 수 있었다.

• 터널과지하공간
• /
• 제24권6호
• /
• pp.449-463
• /
• 2014

국내의 경우 슬러리나 페이스트 형태로 수압식 충전에 대한 연구와 다양한 폐광산 현장에 적용한 사례는 많으나, 공압식 충전에 대한 연구는 진행되지 않고 있다. 기존의 공압식 충전법은 강관의 구부러진 곳에서 충전재 유동에 의한 마모에 의해 강관의 손상이 발생한다. 이와 같은 문제점을 개선하기 위하여 새로 고안한 개량형 노즐을 이용한 공압식 충전법을 개발하였다. 본 연구에서는 접근이 가능하거나 불가능한 채굴공동을 모사하여 실험실에서 모형실험을 수행하고 그 충전효율을 평가하였다. 갱내 충전법 실험에서는 토출각의 변화, 모래의 투입량 및 입자 크기에 따라 충전효율을 분석하였으며, 지상 충전법 실험에서는 중력식, 재래식 및 개량형 충전방법의 실험으로부터 충전효율을 분석하여 개량형 공압식 충전법의 우수성을 입증하였다.

• 한국기계가공학회지
• /
• 제13권4호
• /
• pp.21-27
• /
• 2014

The injection molding process has several advantages enabling it to produce large quantities of molded plastic products using a repetitive process. In recent years, it has been necessary to develop an injection molding process with micro/nano-sized patterns for application to the semiconductor industry and to the bio/nano manufacturing industry. In this study, we apply gas pressure to the inside of a mold and consider the gas dissolution phenomenon for a resin filling into a micro pattern with a line structure. Using numerical analysis, we calculate the filling ratio with respect to time for various internal gas pressures and various aspect ratios of the micro-patterns.

• Journal of Welding and Joining
• /
• 제32권3호
• /
• pp.11-18
• /
• 2014

TSV(through silicon via) filling technology is making a hole in Si wafer and electrically connecting technique between front and back of Si die by filling with conductive metal. This technology allows that a three-dimensionally connected Si die can make without a large number of wire-bonding. These TSV technologies require various engineering skills such as forming a via hole, forming a functional thin film, filling a conductive metal, polishing a wafer, chip stacking and TSV reliability analysis. This paper addresses the TSV filling using Cu electrodeposition. The impact of plating conditions with additives and current density on electrodeposition will be considered. There are additives such as accelerator, inhibitor, leveler, etc. suitably controlling the amount of the additive is important. Also, in order to fill conductive material in whole TSV hole, current wave forms such as PR(pulse reverse), PPR(periodic pulse reverse) are used. This study about semiconductor packaging will be able to contribute to the commercialization of 3D TSV technology.

• 한국생산제조학회지
• /
• 제21권1호
• /
• pp.26-32
• /
• 2012

In the present study, the stencil printing process using solder paste are numerically analyzed. The key design parameters in the stencil printing process are the printing conditions, stencil design, and solder paste properties. Among these parameters, the effects of printing conditions including the squeegee angle and squeegee pressure are investigated through finite element (FE) analysis. However, the FE analysis for the stencil printing process requires tremendous computational loads and time because this process carries micro-filling through thousands of micro-apertures in stencil. To overcome this difficulty in simulation, the present study proposes a two-step approach to sequentially perform the global domain analysis and the local domain analysis. That is, the pressure development under the squeegee are firstly calculated in the full analysis domain through the global analysis. The filling stage of the solder paste into a micro-aperture is then analyzed in the local analysis domain based on the results of the preceding global analysis.