• Journal of the Korea Convergence Society
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• v.6 no.1
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• pp.43-48
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• 2015

We studied on the injection molding conditions of defect-free PMMA lens for surgical light. When the heat temperature of mold is low, more imperfect molding or weldlines and flow marks have showed. A defective lens depends on low fluidity of the PMMA resin and its temperature is high, a flexural strain has occurred. The longer cooling time of specimens, the more cracks have occurred due to resin crystallization. In this study, optimal molding conditions for defect-free PMMA lens is as follows. The heat temperature of core mold was 110 [$^{\circ}C$] and also the cooling time was 25 [sec]. PMMA materials can realized low expense to produce plastic optical lens and applications.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.5737-5742
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• 2015

Insert injection molding is a process in which molten plastic is injected into a mold that contains a pre-placed insert. During the injection stage, the insert can be deformed by the pressure applied by the polymer melts. The deformation of the insert changes the width of the flow path around the insert, which can cause several defects such as short shots or warpages of the parts. In order to reduce the deformation of the insert, it is important to achieve successful design of gating system, insert geometry, and molding conditions. In the present study, the insert deformations that occured during the injection molding of the BLDC motor stator were investigated by numerical analyses. The gate location and the insert shape were modified to reduce the insert deformation. Finally, the injection molding with the modified designs was carried out, and it was confirmed that the insert deformation was reduced.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.1
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• pp.39-46
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• 2013

This study aims to develop a plastic aspheric lens for a 13-megapixel mobile phone camera by injection-compression molding. A mold for injection-compression molding experiments was fabricated with a movable upper plate and four springs. During cavity filling for an aspheric lens with a thickness ratio of 2, a weldline was formed under conventional injection molding, whereas no weldline was formed under injection-compression molding with a compression stroke of 0.3 mm. The flow patterns were in good agreement with the simulation results. The birefringence decreased as the compression stroke increased, and the birefringence produced by injection-compression molding was very low and more uniform compared with that produced by injection molding. In addition, the bulk birefringence of an assembly composed of four plastic lenses was significantly affected by the orientation of the lenses to be mounted.

• Journal of fish pathology
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• v.19 no.2
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• pp.127-139
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• 2006

From 2002 to 2004, various vibrios were isolated from the olive flounder, Paralichthys olivaceus of culturing size with disease signs. During this survey, it was known that the high proportion of Vibrio ichthyoenteri was occupied among the isolated vibrios. Generally, V. ichthyoenteri is well known as the pathogen of bacterial enteritis of olive flounder larvae. The aim of the present study was the compare the characteristics of two groups of V. ichthyoenteri, culturing sized olive flounder, and larvae of olive flounder showing the intestinal necrosis. The research was focused on the physiology, biochemistry, genetics in the two bacterial groups. The physiological and biochemical characteristics of the tested strains were very similar. The intergenic spacer (IGS) region between the 16S and 23S rRNA genes of 21 isolated strains and 3 reference strains, V. ichthyoenteri, were investigated by PCR fragment length typing and DNA sequencing. After the isolated strains were identified as V. ichthyoenteri, not only phenotypic characteristics of the isolated and reference strains but also homology of 16S-23S IGS of all isolated strains and reference strains as 99.1~100%. The V. ichthyoenteri showed 4 specific 16S-23S patterns and contained no-tRNA, tRNAGlu(TTC) , tRNAIle(GAT) tRNAAla(TGC) type .

• Korean Journal of Social Welfare
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• v.68 no.3
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• pp.5-27
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• 2016

In this study, we examine differences in the children's medical utilization by family structure with a focus on single-mother and single-father families using data from the Korean Health Panel Survey, years 2008~2012. We also investigate whether the cause of transition into a single-parent household, whether coresidence with children's grandparents, and number of siblings are associated with children's use of ambulatory visits. The main findings of this study are as follows. First, children who grew up in single-father households had fewer ambulatory visits compared to those living with both parents after controlling for children's demographic characteristics and family backgrounds. Second, coresidence with grandparents was not associated with children's medical utilization. However, number of siblings was significantly and negatively correlated with the use of ambulatory visits. Third, children living with a divorced father had fewer medical utilization compared to those living with a widowed father, and coresidence with grandparents was positively associated with children's use of ambulatory visits. Our findings suggest that tailored policy supports would be more fruitful based on characteristics of single-parent households such as gender of parents, and the supports should also pay more attention to health care needs and medical utilization of children.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.472-475
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• 1997

It is well known that pneumatic motors convert fluid power into mechanical power with a low efficiency. The Value of the efficiency depends on several factors, of which the most important are ; type of motor, speed, supply pressure, sie and geometry of the motor. This paper presents an analytical and experimental study of the performance of he vane type pneumatic motors. This investigation deals with all the pneumatic motors. This investigation deals with all the pneumatic motors. This investigation deals with all the major aspects of the air flow through a vane type pneumatic motor and pints out which are the main causes of the low efficiency of the motor, and therefore indicates which changes in a motor design an lead to optimum performance.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.30 no.1
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• pp.64-70
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• 1994

선택어획의 궁극적인 목적은 미성숙어의 남획과 혼획을 방지하여 일정크기의 체장이 되었을 때 계속적으로 생산을 유지하기 위한 것이다. 그러나 일찍부터 Huxley의 Doctrin 같은 논리에서부터 시작하여 수산자원의 특성과 관련한 제문제와 어로기술의 급진적 발전으로 인한 어획량의 증가에 따라 어족자원의 감소는 심각한 수산현안의 문제로 되고 있지만, 우리나라는 아직 자원관리를 위한 어업기술의 방향이 모색되고 있지 못하는 것 같다. 이러한 점에서 균형적인 어업분야의 발전을 위해서는 하드에 적합한 소프트의 개발과 선택은 물론이고 소프트를 현실에 맞게 적용할 수 있는 하드의 개발이 필요한 것 같다. 어업기술면만 보더라도 생역화를 위한 어로기기의 개발, 자원관리형 어구, 어법의 개발 등의 소프트와 어업학이라는 하드의 조화가 최근 수산분야의 중요한 일면임에 틀림이 없을 것이다.(이 논문의 결론부분임)

• Journal of Korean Library and Information Science Society
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• v.36 no.2
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• pp.327-348
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• 2005

The purpose of this study is to emphasize the importance of index definition and to prepare the basis of optimal index in bibliographic retrieval system. For the purpose, this research studied a index extraction theory on index tag definition and index normalization from the bibliographic marc database and analyzed a retrieval utilization rate of extracted index. In this experiment, we divided index between text-type and code-type about the generated 29,219,853 indexes from 2,200,488 bibliographic records and analyzed utilization rate by the comparison of index-type and index term of web logs. According to the result, the text-type indexes such as title, author, publication, subject are showed high utilization rate while the code-type indexes were showed low utilization rate. So this study suggests that the unused index is removed from index definition to optimize index.

• Journal of Science Education
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• v.38 no.1
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• pp.29-40
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• 2014

The new paradigm of the 21st Century science education explores a wide range of possibilities that can foster students' interest toward science and creative convergence thinking. The purpose of this study was to utilize science visual media that can improve students' scientific creativity and artistic sensibility. Curriculum reorganization can be one solution for the primary convergence science teaching and learning strategies using science visual media. Through a new and exciting experiment to a various science visual media such as science picture, TV film, movie, UCC, etc., we hope this teaching and learning strategy can increase the students' scientific interest and attitude.

• Journal of the Korean Wood Science and Technology
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• v.10 no.1
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• pp.38-46
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• 1982

The research was carried out to determine the division of juvenile and adult wood from the pattern of variables of wood quality indicators, to investigate general low of the size of juwenile wood and to study the characteristics of juvenile and adult wood. For this study some trees of Pinus koraiensis were selected and several wood quality indicators such as annual ring width. late wood percentage, tracheid length tracheid diameter, wall thicknes, and microfibril angles were measured. The results of this study were summaried as follows. 1) Juvenile and adult wood can be divided into radial variations of wood quality indicators. In this study juvenile wood might be classified as a large fluctuated region of radial wood quality variations in the nearest part to pith. 2) Juvenile wood was indicated as a part of nearly cylinderical shape, averaging 6-11cm in radius, near pith. 3) Number of rings from pith of juvenile wood was about 12-20 and was nearly constant in uniform growth trees among the forest stands. 4) Usually adult wood was formed within the about 5-10m above ground.