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유리섬유 보강 EP 소재의 피로거동에 미치는 Hole Notch의 영향
이정무(Jeong-Moo Lee),서기정(Ki-Jeong Seo),이은동(Eun-Dong Lee),김태진(Tae-Jin Kim),이언석(Eon-Seok Lee) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
This paper reports on an investigation into the effect of hole notches on the injection molded specimens. In order to evaluate the effects of stress concentration and interaction on fatigue behavior, holes were introduced as notch to simple specimen. The material was used in mPPO. Fatigue tests were conducted at 1-hole notch and 2-hole notch specimens. Also, the FEMFAT was used to predict the fatigue life of different hole notch type conditions. The increase of diameter and quantity of hole notch reduced the fatigue strength and fatigue life. As the distance and angle between two holes increase, the fatigue life of the specimen increases. The prediction of FEMFAT gives valid results by considering the various factors of fatigue effect.
강동우(Dongwoo Kang),이언석(Eon-Seok Lee),이승현(Seung-hyun Lee),이택민(Taik-min Lee) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
Interest in the production of printed electronics using a roll-to-roll system has gradually increased due to its low massproduction costs and compatibility with flexible substrate. To improve the accuracy of roll-to-roll manufacturing systems, the movement of the web needs to be measured precisely in advance. In this paper, a novel measurement method is developed to measure the displacement and velocity of the web precisely and directly. The proposed algorithm is based on the traditional single field encoder principle, and the scale grating has been replaced with a printed grating on the web. Because a printed grating cannot be as accurate as a scale grating in a traditional encoder, there will inevitably be variations in pitch and line-width, and the motion of the web should be measured even though there are variations in pitch and line-width in the printed grating patterns. For this reason, the developed algorithm includes a precise method of estimating the variations in pitch. In addtion, a method of correcting the Lissajous curve is presented for precision phase interpolation to improve measurement accuracy by correcting Lissajous circle to unit circle. The performance of the developed method is evaluated by simulation and the measurement accuracy is less than 6.5um while the web is traveling 100mm.
수소생산균 Enterobacter sp. ES392의 분리 및 배양조건
전숭종 ( Sung Jong Jeon ),이언석 ( Eon Seok Lee ) 한국미생물생명공학회 ( 구 한국산업미생물학회 ) 2010 한국미생물·생명공학회지 Vol.38 No.4
수소 생산 균주 ES392는 부산 소재 동의대학교에 위치한 연못 담수에서 분리하였다. 세포는 직경 0.6μm, 길이 1.4μm의 간균이고 편모와 포자를 형성하지 않았다. 분리된 균주의 16s rRNA 염기서열과 생화학적 특성을 바탕으로 계통 학적으로 분류한 결과, ES392 균주는 Enterobacter sp.에 속하는 것으로 동정되었다. 수소생산을 위한 생육최적 pH와 온도는 각각 7.5와 35oC이었다. 분리한 Enterobacter sp. ES392 균주의 수소생산을 최대화 하기 위해 배지성분을 최적화하였다. 그 결과 4%(w/v) sucrose, 0.5%(w/v) yeast extract, 50mM potassium phosphate를 첨가한 배지 조건에서 최대수소생산량을 나타내었다. 회분식 배양 조건에서 최대 수소 생산량은 3481mL/L이었고, 수소생산수율은 1.33mol/mol sucrose를 나타내었다. A hydrogen-producing bacterium (strain ES392) was isolated from pond water located in the Dong-Eui University, Busan, Korea. The cell was long-rod type (1.4μm) of about 0.6μm in diameter, and not formed flagellum and spore. Phylogenetic analysis based on the 16S rRNA sequence and biochemical studies indicated that ES392 belonged to the genus Enterobacter sp. The optimum pH and temperature for hydrogen production was 7.5 and 35oC, respectively. The optimization of medium compositions which maximize hydrogen production from Enterobacter sp. ES392 was determined. As a result, the maximum hydrogen production was obtained under the conditions of 4% (w/v) sucrose, 0.5% (w/v) yeast extract and 50mM potassium phosphate buffer (pH 7.5). Under batch culture conditions, the maximal hydrogen production and yield were obtained as 3481mL/L and 1.33mol/mol sucrose, respectively.
스트레인 게이지를 사용한 소형 제품의 개폐 피로수명 평가
고일민(Il-min Ko),김선우(Sun-Woo Kim),박정민(Jungmin Park),이언석(Eon-Seok Lee) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
Nowadays most of phone makers have been performing an open-and-close test to evaluate the fatigue resistance of their phone in the final stage of product development. However it is more useful than CAE analysis or other estimations by using S-N curve, this simple open-and-close test only gives the failure cycle of the phone as a signal of phone housing crack. We suggest the more advanced open-and-close test method that gives part designer several meaningful design data such as local deformation and stress level by using strain gage. It can automatically measure strain or stress level, unbalance of fatigue stress during open-andclose test. Therefore using those data, phone designer can forecast of stress type of product, crack initiation and failure time of phone housing parts and finally more reliable design can be attained. Some real cases are introduced.
박정민(Jungmin Park),김선우(Sun-Woo Kim),방선호(Sun-Ho Bang),이언석(Eon-Seok Lee) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
For the reliable FEM analysis result, accurate material properties are required, before everything else, the true stress-strain relationship is the basic property for the structural analysis with FEM. In this paper, the easy, rapid and effective image processing method is presented to observe the large deformation behavior and to measure the true stress-strain relationship of PC and PC/ABS. This image processing system is composed with CCD camera, digital image acquisition and processing system. It measures the axial and lateral displacement of rectangular tensile test specimens and calculates simultaneously the true stress and true strain during the uni-axial tensile test. The Poisson’s ratio and area reduction ratio can be experimentally calculated at post-yield stage, at which traditional extensometers and strain gages cannot be used and the digital image correlation (DIC) method, which is currently used, might be somewhat tedious.