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성재혁(Jae Hyuck Sung),곽병만(Byung Man Kwak) 한국자동차공학회 1997 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1997 No.6_2
In this paper. a simple way of topology optimization is studied. The optimization problem is formulated as a nonlinear programming and solved by using design sensitivity analysis. The adjoint variable method is used efficiently for the sensitivity calculation. Material properties in terms of density distribution are taken as design variables. A simplified explicit relation between density and material properties is used without introducing microstructures as done in the literature. This approach is general and easily implementable suing existing codes.<br/>
정용현(Yong Hyun Chung),한정희(Jeong Hee Han),성재혁(Jae Hyuck Sung),송경석(Kyung Seuk Song),임경택(Kyung Taek Lim),유일재(Il Je Yu) 한국실내환경학회 2005 한국실내환경학회지 Vol.1 No.2
140 buildings of Korean major cities were investigated for the presence of asbestos and man made mineral fibers (MMMF) in their construction materials. 73 (52%) and 84 (60%) buildings contained asbestos and MMMF in their construction materials, respectively, and 17 (12%) buildings contained both asbestos and MMMF. 75% of the asbestos containing buildings were mostly constructed during 1970"s. 100% of underground shopping arcades, 90% of manufacturing workplaces, 84% of train and bus terminals had the asbestos containing construction materials. The manufacturing workplaces of Daejeon (89%) and Daegu (89%), which mostly had been built in the past, used asbestos containing building materials, while the building in Seoul, Busan and Jinju, which were constructed recently, used relatively lower asbestos containing building materials with 46%, 28%, and 33%, respectively. 9 building materials that have been widely used in Korea were analyzed using a transmission electron microscope equipped with energy dispersive X-ray analyzer (TEM-EDX) for their mineral contents. All asbestos fibers showed typical characteristics of chrysotile fibers with hollow tube structure. The average diameter ranged from 0.03㎛ to 0.05㎛, and the average length were ranged from 7.5㎛ to 12.0㎛. Atomic percentages of asbestos fibers were 51.9∼55.9% of Mg, 41.3∼44.3% for Si, and 2.7∼4.8% for Fe.
정용현(Yong Hyun Chung),한정희(Jeong Hee Han),성재혁(Jae Hyuck Sung),송경석(Kyung Seuk Song),임경택(Kyung Taek Lim),유일재(Il Je Yu) 한국실내환경학회 2005 한국실내환경학회지 Vol.1 No.2
Twenty three samples of man-made mineral fibers (MMMF) were collected and analyzed for their mineral contents using a transmission electron microscope equipped with energy dispersive X-ray analyzer (TEM-EDX). Five glass fibers showed a straight fiber type without branches with average diameter ranged from 2.6㎛ to 5.6㎛ and average length 12.2~29.6㎛. The major atomic compositions of the glass fibers were Na, Mg, Si, Ca, and Fe with a little variance among them and contained trace amounts of Al and Si. Eleven rock wool fibers also showed a straight fiber type without branches. The rock wool fibers used in 3 insulation panel and 1 insulation tube had average diameter 13.6~26.4㎛ and average length 13.6~26.4㎛. The major atomic compositions of the rock wool fibers were Na, Mg, Al, Si, S, Ca, Fe, and Cu with a little variance among them. Two of rock wool sealant fibers and one of coating material fibers had average 0.8~2.2㎛ diameter and 9.9~16.2㎛ average length. The major atomic compositions of the fibers were Mg, Al, Si, Ca, and Fe with a little variance among them and contained trace amount of S. The fibers in the rock wool coating materials contaminated partially with another type of fibers. Four of rock wool ceiling board showed 0.9~2.04㎛ average diameter and 4.3~15.2㎛ average length. The major atomic compositions of the fibers were Mg, Al, Si, S, Ca, and Fe with a little variance among them and contained trace amounts of Na, K, and Ti. Three of long glass fibers showed a mass appearance with finely splitted fibers, and the major atomic compositions of the fibers were Na, Mg, Al, Si, S, Ca, and Fe with no variance among them. One type of ceramic fiber showed 2.9±1.59㎛ average diameter and 20.3±9.38㎛ average length. The major compositions of the fibers were Al, Si, and S. A gypsum board and a perlite and a calcium silicate insulation material all showed aspect ratio less than 3:1, indicating non-fibrous materials. The major compositions of the gypsum board particles were Al, Si, S, K, Ca, and Fe, The perlite particles were consisted of Na, Al, Si, S, K, Ca, and Fe, and the calcium silicate insulation materials were mainly consisted of Al, Si, Ca, and Fe.
정용현(Yong Hyun Chung),한정희(Jeong Hee Han),성재혁(Jae Hyuck Sung),유일재(Il Je Yu) 한국독성학회 2006 Toxicological Research Vol.22 No.3
Two kinds of sepiolite, a 500℃ heat-treated sepiolite, and a 700℃ heat-treated sepiolite were analyzed for their physicochemical properties. After these sepiolites were instilled into rat lungs, the effects of the substances on lung pathological changes were evaluated. The lungs instilled with sepiolite increased their weight compared with the unexposed control. The pathological examination further showed increased legions of granuloma with early fibrosis. The heat treated sepiolites, however, did not show any toxicological differences from the untreated sepiolites. Thus chronic experiments are needed to evaluate the durability of mineral fibers, which is an essential experiment for evaluating biopersistence of fibers in lungs.