• Composites Research
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• 제26권4호
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• pp.213-217
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• 2013

The focus in the present work is to study the agro-waste corn husk bio-filler as reinforcement for polypropylene. These materials have been created by extrusion and injection molding. The effect of filler content by 10, 20, 30 and 40 wt. % and mesh sizes of 50~100, 100 and 300 on the mechanical properties was studied. For the un-notched specimens, the results of flexural strength showed a declining trend with increase the filler loading and the results of impact strength showed an increasing trend with increase the mesh size. In contrast, enhanced flexural modulus was observed with increasing filler loading and size.

• 대한인간공학회지
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• 제5권2호
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• pp.17-25
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• 1986

In recent years, the average life span of people in advanced countries has increased. Conwequently, the number of middle-aged and old workers who have the will to work has increased. On the other hand, the declining birth rate has decreased the number of young workers. However, because many enterprises in advanced countries have extended their mandatory retirement age from 55 to 60 years, labor accidents involving aged workers are on the increase. As a result, the need for a method to evaluate the work skills of middle-age and old workers has become urgent. To explore one such method, this study investigated the relationship between aging and manual dexterity. Dexterity was found to deteriorate with age, but with large variability from individual to individual. The parameters of dexterity used in this experiment were found to be reliable.

• KDI Journal of Economic Policy
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• 제39권4호
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• pp.1-23
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• 2017

I measure aggregate productivity growth in manufacturing between 1995 and 2013 as defined by Petrin and Levinsohn (2012). I decompose aggregate productivity growth into technical efficiency improvements, resource reallocations, and net entry effects. I find that aggregate productivity growth slows down after 2004 and that the rapid drop in technical efficiency growth contributed most to the decline. In this paper, I focus on the role of young plants with regard to productivity growth of Korean manufacturing. I show that young plants account for nearly half of APG (48%), while their value-added share is 14 percent on average between 1995 and 2013. I find that productivity growth at young plants has been declining for the last ten years. The lower growth of continuing young plants contributes to this trend. These results stress the important role of young plants in aggregate productivity growth and imply that understanding the dynamics of young plants is necessary to form effective start-up policies.

• 대한기계학회논문집A
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• 제28권10호
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• pp.1509-1516
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• 2004

During fuel irradiation tests, all parts of cylindrical structure with multiple holes act as heat sources due to fussion heat and ${\gamma}$-flux. The high temperature is especially generated in the center of pellet. Because of the high temperature, many problems occur, such as melting of pellet and declining of heat transfer between cladding and coolant. In this paper, it is attempted to minimize the temperature of pellet using optimization method. For thermal and optimization analysis of structure, the finite element method code, ANSYS 5.7 is used. Through the optimum design process, the temperature of SBT diminished 10％ and the temperature of OBT diminished 18％.

• KSBB Journal
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• 제8권5호
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• pp.504-507
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• 1993

Control culture에서 embryo 생성률이 6개월 동안 1000embryos/ml에서 500embryo/ml로 감소되었다. 이러한 현상을 극복하기 위한 방법으로 embryo 배양액에서 추출된 세포외 물질의 첨가는 embryo 생생률을 control culture와 비 교 하여 최 대 (2500embryos/ml)까지 증가시켰다. 또한 세포외 단백질이 embryo 수율 향상에 기인하는 것으로 추측된다.

• KSBB Journal
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• 제26권3호
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• pp.183-188
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• 2011

Adult stem cells, which have characteristic of self-renewal and multipotency, are specialized cell types, responsible for the tissue regeneration of the damaged tissue. Recent studies suggest that stem cells senescence (or stem cells' ageing) is closely associated with the variety of ageing-related phenotypes such as tissue atrophy, degenerative diseases and onset of cancers. During ageing, declining of stem cells function and subsequently occurring mal-differentiation of stem cells would be important to understand the biological process of development of ageing-related phenotypes such as tissue degenerations and cancers. This review focuses on the DNA damage stress as a cause of senescence of stem cells and their mal differentiation, which is closely link to defect of regeneration potentials and neoplastic transformation. Understanding of molecular mechanisms governingsuch events is likely to have important implications for developing novel avenues for balancing tissue homeostasis longer period of time, further leading to 'Healthy ageing'.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제11권2호
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• pp.127-141
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• 2007

This paper compares and analyzes mathematics teachers' understanding of students' mathematical comprehension after experiences with the Cognitively Guided Instruction (CGI) or the Development of Mathematical Ideas (DMI) teaching strategies. This report sheds light on current issues confronted by the educational system in the context of mathematics teaching and learning. In particular, the declining rate of mathematical literacy among adolescents is discussed. Moreover, examples of CGI and DMI teaching strategies are presented to focus on the impact of these teaching styles on student-centered instruction, teachers' belief, and students' mathematical achievement, conceptual understanding and word problem solving skills. Hence, with a gradual enhancement of reformed ways of teaching mathematics in schools and the reported increase in student achievement as a result of professional development with new teaching strategies, teacher professional development programs that emphasize teachers' understanding of students' mathematical comprehension is needed rather than the currently dominant traditional pedagogy of direct instruction with a focus on teaching problem solving strategies.

• 수산경영론집
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• 제39권1호
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• pp.1-16
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• 2008

For the last few years, the wholesale market system in Japan has been experiencing a lot of changes in the related sectors. The greatest changes in the environments surrounding the wholesale market were enlargement of the producers' cooperatives, increase of fisheries products marketed in the outside of the wholesale market system, and management aggravation of the related businessmen, These changes resulted in the revision of the wholesale Market Law in 1999 to cope with the social needs successfully. Recently, fisheries wholesale markets in Japan have a few problems like declining of earning power, weakening of management constitution, etc. Consequently, Japanese government presents policy for enforcing the competition power through reform laws related with fisheries wholesale markets. Also the fisheries wholesale markets have been trying variety and active countermeasures like undertaking, merger, coalition, etc. to overcome the crisis.

• 디자인학연구
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• 18호
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• pp.199-207
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• 1996

기계테크놀로지의 발달로 수작업을 중심하는 공예산업이 사양화 되고잇다. 산업혁명에 대한 당시의 사회문제를 비판했던 러스킨과 모리스의 사상은 오늘날가지 영향을 미치고 있다. 본연구는 공예활동의 발전과 위상정립을 위하여 그들의 사상을 중심으로 공예 본질적 개념을 정리하고 공예 사회적 역할을 논하고자 하였다. 기게생산에 의한 반발로 소비자의 취향이 개성화를 요구하고 생산라인의 소량다품종화의 문제를 공예적 생산방법으로 해결할 수 있다는 것은 공예생산의 존제 필요성을 입증하며 더욱이 대주으이 정신적생활이 중시되는 현시점에서 공예의 사회적 역할로써 기계적생활에 대한 감성적생활의 교육적 역할이 중요함을 논했다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.287-292
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• 2001

This paper investigates the properties of high fluidity concrete incorporating lime stone powder and fly ash. Lime stone powder(LSP) and fly ash(FA) contents are varied with. According to test results, as LSP and FA contents increase, fluidity, air content and placeability shows a declining tendency. For the temperature history, both LSP and FA have favorable effects on reducing hydration heat, moreover, LSP reduces hydration heat more than FA. LSP shows undesirable strength loss as its content increases. FA also decreases the strength at early age, but it enhances later age strength. Accordingly LSP is expected to improve the quality at fresh concrete and reduce hydration heat, while it causes strength loss.