• Journal of the Korean Institute of Gas
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• v.8 no.2 s.23
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• pp.15-27
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• 2004

The purpose of this paper is to improve the performance of Polymer electrolyte fuel cell(PEMFC) by studying the channel dimension of bipolar plates using commercial CFD program 'Fluent'. Simulations are done ranging from 0.5 to 3.0mm for different size in order to find the channel size which shoves the highst hydrogen consumption. The results showed that the smaller channel width, land width, channel depth, the higher hydrogen consumption in anode. When channel width is increased, the pressure drop in channel is decreased because total channel length Is decreased, and when land width is increased, the net hydrogen consumption is decreased because hydrogen is diffused under the land width. It is also found that the influence of hydrogen consumption is larger at different channel width than it at different land width. The change of hydrogen consumption with different channel depth isn't as large as it with different channel width, but channel depth has to be small as can as it does because it has influence on the volume of bipolar plates. however the hydrogen utilization among the channel sizes more than 1.0mm which can be machined in reality is the most at channel width 1.0, land width 1.0, channel depth 0.5mm and considered as optimum channel size. The fuel cell combined with 2cm${\times}$2cm diagonal or serpentine type flow field and MEA(Membrane Electrode Assembly) is tested using 100W PEMFC test station to confirm that the channel size studied in simulation. The results showed that diagonal and serpentine flow field have similarly high OCV and current density of diagonal (low field is higher($2-40mA/m^2$) than that of serpentine flow field under 0.6 voltage, but the current density of serpentine type has higher performance($5-10mA/m^2$) than that of diagonal flow field under 0.7-0.8 voltage.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.42.1-42.1
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• 2010

결정질 실리콘 태양전지의 전면 전극은 전극 면적으로 인한 손실(shading loss)를 줄이고 단락전류밀도(Jsc)를 높이기 위해 전극 너비를 줄이는 노력을 하고 있다. 하지만 전극 소성(firing) 시 전면 전극의 핑거(finger)와 버스바(busbar)의 너비 차이로 인해 전극 침투(fire-through) 정도가 달라질 수 있다. 본 연구에서는 전극 소성 공정 시 전면 전극의 너비에 따른 전극 침투 정도를 조사하기 위해 접촉 저항(specific contact resistance)과 재결정화(Ag recrystallite) 된 전면전극의 분포에 대해 비교하였다. 접촉 저항을 측정하기 위하여 transfer length method(TLM)를 이용하였다. 또한 전면 전극층을 제거한 후 실리콘 기판의 재결정 분포를 주사전자현미경(Scanning electron microscope : SEM)을 이용하여 관찰하였다.

• Fashion & Textile Research Journal
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• v.1 no.3
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• pp.252-258
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• 1999

The aims of this study is to classify the lower somatotype of adult women and appearance analysis on the shape of flare skirts by using the image processing. Also We have made skirts in order to analyze the various types of appearance of flare skirts by using the image processing. The subjects for our wear test lower somatotype, who were controlled in their waist, abdomen and hip shapes. The flare skirts used for wear test were 112 types(combinated 14 fabric type and 8 lower somatotype). The effect of lower somatotype on the shape of flare skirts was determined by the horizontally hem line section shape and the silhouette of flare skirts with image processing. The data were analyzed by using analysis of variance and Turkey, Duncan multiple range test. The results obtained are summarized as follows: It is shown that the fabric weight elongation differs in fabrics properties, in direction of textures. The shape horizontal section of flare skirt hem line has differed with the number of nodes, wave-height of nodes and breadth of silhouette by fabrics properties and lower somatotype. It is noticed that the breadth of flare skirts by the silhouette has high correlation with the drape ability of fabrics and lower somatotype. Results for our flare skirts show changes in amplitude and mean with fabrics, somatotype. Therefore we can say that gray-level histograms are correlated with changes in appearance, differences in drape spacing and related fabric properties and their somatotype.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.168-169
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• 2003

Ti：LiNbO$_3$ 광도파로는 확산형 도파로이기 때문에 그 도파특성이 확산공정 조건에 크게 의존할 뿐만 아니라 굴절률 분포를 모델링하기가 어렵다. 이러한 이유로 설계된 Ti：LiNbO$_3$ 광도파로의 특성은 실제 제작된 소자와 큰 차이를 보이는 경우가 많은데, 이를 개선하기 위해서는 각 공정파라미터에 따른 도파 특성의 변화를 파악하는 작업이 우선적으로 수행되어야 한다. 본 논문에서는 서로 다른 너비를 갖는 Ti strip을 동일한 확산조건에서 확산시킨 후 제작된 광도파로의 도파손실 및 모드패턴을 측정하였다. (중략)

• Communications of Mathematical Education
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• v.23 no.3
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• pp.785-801
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• 2009

The education of mathematics is comprised of formal thoughts so students lose interest and they don't have a chance to have a liberal mind. To solve this problem, recently, the flow of mathematic education is changing from formal mathematics to experimental mathematics, which focuses on student's activity and experience. Experimental mathematics can improve student's interest and participation. This study is about teaching methods of trigonometric functions through experimental mathematics measuring height and width of buildings. For measuring height of buildings we use clinometer and for measuring width of buildings we developed a mathematical tool with which we can measure angle for width of buildings. Through this activity, students obtained an interest in mathematics and they gained a positive attitude for the lesson. If we use this experimental mathematics method in high school, it's possible to reduce fears of mathematics and to increase an interest for mathematics.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.2 no.2
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• pp.62-67
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• 2009

Purpose: The purpose of this study is to find out the accuracy and usability of the three dimensional ultrasonography in measuring the size of the rotator cuff tear, especially before and after the injection of normal saline into the glenohumeral joint. Materials and Methods: 14 patients of rotator cuff tear who were diagnosed and operated from August 2007 to September 2008 were included in this study and authors compared the size of rotator cuff tear measured with three dimensional ultrasonography with the real size measured intraoperatively. In preoperative ultrasonographic evaluation, horizontal and longitudinal length of rotator cuff tear before and after injection of normal saline intraarticularly. During the arthroscopic operation the size of tear was measured by passing a Kirschner wire through a spinal needle and direct measure was performed in open surgery. Results: The average difference was 8 mm in horizontal and 1.9 mm in longitudinal length of tear without saline injection between ultrasonographic and intraoperative measure. The average difference was 4.1 mm in horizontal and 1.6 mm in longitudinal length of tear after the normal saline injection. Conclusion: In three dimensional ultrasonographic evaluation in rotator cuff tear, intraarticular normal saline injection would produce more accurate results.

• Journal of the Korea Society of Computer and Information
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• v.24 no.10
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• pp.117-127
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• 2019

The purpose of this study was to analyze the direct measurement data of 40-59 year old middle-aged men from Size Korea's 7th anthropometric survey, and to identify the body shape characteristics and to type the body shape of middle-aged men. Through this, this study aimed to provide basic data necessary for the clothing patterns of middle-aged men with excellent fit. The data was SPSS Ver. 24.0 program analysis. Factors extracted six including body horizontal, vertical, shoulder, waist front length, leg thickness, and shoulder deflections. The body shape of middle-aged men was classified into three types. Type 1 had a thin body circumference, a narrow width, a low height, a short waist front length, and a thin ankle and calf. Type 2 had a high body height, a long waist front length, a normal circumference and width, a thick ankle, a calf, and a sagging shoulder. Type 3 had a large body circumference, a wide body, a wide shoulder, and a long waist front length. A prominent feature of the changes in body shape of middle-aged men is the increase in the circumference and thickness items due to abdominal protrusion and fat accumulation. Therefore, pattern design according to these physical characteristics is considered to be necessary.

• Journal of the Korean Society of Radiology
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• v.14 no.7
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• pp.871-879
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• 2020

The purpose of this study was to analysis the correlation between kidneys function indicators and these size in ultrasonography. A total of 170 (male:86, female:84) patients of sex and age groups were examined by abdominal ultrasonography. The patients classified as those in their 20's, 30's, 40's, and over 50's. We measured the length, width, and cross-sectional height of the kidneys twice. At this time, the length of these were measured from the maximum upper to the maximum lower pole and the widest width in the same ultrasonography was measured to obtain the cross-sectional area. Other relevant indicators included body surface area, serum creatinine, glomerular filtration rate (GFR), MDRD (Modification of diet in renal disease) and C-G (Cockcroft-Gault). Significant comparisons of differences between relevant factors by age groups and sex were conducted with a one-way distribution analysis. Correlation analysis was also performed between relevant factors by using Pearson and Spearman correlation coefficient. It was defined as meaningful when the p-value was less than 0.05. As a result, the length, the width, and the cross-sectional area of kidneys were correlated with GFR, C-G, MDRD. Therefore, it is expected that the accuracy of diagnosis of kidneys disease will be increased if the relevant indicators are evaluated together rather than measuring only length of these in ultrasonography.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.112-112
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• 2016

열전 발전은 버려지는 폐열을 재사용 가능한 에너지로 전환할 수 있다는 점에서 차세대 청정 에너지원으로 분류되며, 19세기 초 발견된 이래 꾸준히 연구되어온 연구 분야이다. 특히 1990년대 열전소재로의 나노 기술의 접목에 따라 열전성능(figure of merit, ZT)이 2 배 이상 증가 되면서, 고성능의 열전 소재 개발을 위해 나노구조화 연구가 활발히 진행되고 있다. 하지만, 기존의 열전 특성 측정용 상용 장비의 경우, 벌크형 소재를 대상으로 설계되어 연구실 수준에서 개발되고 있는 마이크로미터 스케일의 두께를 가지는 박막형 열전 소재의 두께 방향 (cross-plane)의 열전 특성을 평가하는데 정밀성이 떨어져서 적합하지 않다. 이러한 표준화된 측정 기술의 부재로 인하여 최근 연구되고 있는 나노소재들의 열전 특성 측정 결과를 정확하게 측정하지 못하고 있다 [1] 본 연구에서는 박막형 열전 소재의 열전성능을 평가하는데 가장 중요한 요소인 열전도도를 측정하기 위해 장비를 설계하고, 장비의 측정 능력에 대해 평가하였다. 특히, 측정 포인트 간 큰 온도 차가 발생하여 비교적 쉽게 측정이 가능한 너비 방향 (in-plane) 이 아닌, 온도 차가 작은 박막의 두께 방향의 열전도도를 측정하였다. 그리고 센서의 측정 능력을 평가하기 위해, 폴리이미드를 대상으로 $-10-70^{\circ}C$ 온도 범위에서 측정한 결과와 벌크형 소재 대상으로 신뢰성이 확보된 보호열판법을 이용해 측정한 결과를 비교하였다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2024.01a
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• pp.89-90
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• 2024

본 연구는 와이어 하네스의 불량 여부를 정확하고 빠르게 감지하기 위해 컴퓨터 비전을 활용하여 압착된 단자의 길이, 단자 끝단 치수(너비), 압착된 부분의 폭(와이어부, 심선부)의 6가지 측정값을 계산하는 것을 목표로 한다. 단자 영역별 특징과 배경과 객체 간 음영 차이를 이용하여 기준점을 생성함으로써 값들을 추출하였다. 최종적으로 각 측정 유형별로 99.1%, 98.7%, 92.6%, 92.5%, 99.9%, 99.7% 정확도를 달성하였으며, 모든 측정값에서 평균 97%의 정확도로 우수한 결과를 얻었다.