• 동력기계공학회지
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• 제9권4호
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• pp.137-142
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• 2005

The effects of temperature and initial crack length on impact fracture behavior of side plate material of 35 ton class FRP ship, which are composed by glass fiber and unsaturated polyester resin, were investigated. Impact fracture toughness of GF/PE composites displayed maximum value when the temperature of specimen is room temperature and $50^{\circ}C$, and with decrease in temperature of specimen, impact fracture toughness decreased. Impact fracture energy of GF/EP composites decreased with increase in initial crack length of specimen, and this value decreased rapidly when the temperature of specimen is lowest, $-25^{\circ}C$,. It is believed that sensitivity of notch on impact fracture energy were increased with decrease in temperature of specimen. As the GF/EP composites exposed in low temperature, impact fracture toughness of composites decreased gradually owing to the decrease of interface bonding strength caused by difference of thermal expansion coefficient between the glass fiber/polyester resin. Further, decrease of interface bonding strength of composites with decrease in specimen temperature was ascertained by SEM photograph of impact fracture surface.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 추계학술대회 논문집
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• pp.282-285
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• 2008

In this paper, the numerical analysis of the model without air-guide was carried out in wind power generator. From numerical results, the temperature rise was not satisfied for the class F insulation and the non-uniformity of temperature distribution was a wide difference in heating elements. To improve these problems, the air-guide was installed in front of the coil head of non-drive end(NDE). The short distance between coil head and air-guide was more effective than long distance in cooling performance. Compared to that of the preliminary design, it was found that the cooling performance of the modification design was improved about 12%.

• 한국초전도ㆍ저온공학회논문지
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• 제10권3호
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• pp.32-35
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• 2008

A common problem in many fields of cryogenic power engineering is applying high voltage to cold parts of superconducting apparatus. In many cases, a bushing provides electrical insulation for the conductor which makes the transition from ambient temperature to the cold environment. The 60 kV class cryogenic high voltage bushing for neutral line of the 154 kV / 100MVA high temperature superconducting (HTS) transformer was described. The bushing is energized with the line-to-ground voltage between the coaxial center and outer surrounding conductors; in the axial direction, there was a temperature difference from ambient to about 77 K. For the insulation design of cryogenic bushing, electrical insulation characteristics of the GFRP were discussed in this paper.

• 한국어병학회지
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• 제27권1호
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• pp.1-9
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• 2014

저수온기만 넙치에 대량 폐사를 일으키는 바이러스성 출혈성 패혈증을 폐사가 발생하는 $15^{\circ}C$, 폐사가 발생하지 않는 $20^{\circ}C$에서 인공감염시켜 넙치의 면역 유전자 발현 profile을 cDNA microarray 분석하였으며, 특히 저수온기에 폐사가 나타나는 원인을 면역 유전자 발현과 관련시켜 알아보고자 하였다. $15^{\circ}C$, $20^{\circ}C$의 감염 세포구에 공통으로 발현되는 유전자는 MHC class I, IL-8, myeloperoxidase 및 endonuclease G-like 유전자로 모든 세포표면에 존재하여 항원을 제시하거나 호중구 주화성을 자극하는 유전자들이었다. 항원 가공 및 제시, 항체 생성에 관여하는 MHC class II, immunoglobulin (Ig)과 retinoblastoma 등의 유전자는 $20^{\circ}C$에서는 발현이 증가하였으나 $15^{\circ}C$에서는 발현이 감소되었다. 이로부터 폐사가 발생하지 않는 $20^{\circ}C$는 바이러스 감염초기의 항원 제시, MHC class I과 II에 의한 항원제시, apoptosis 및 이후의 항체 생산이 정상적으로 이루어져 폐사가 발생하지 않는 것으로 생각되었다. 그러나 폐사가 발생하는 $15^{\circ}C$에서는 MHC class I매개의 항원 제시와 탐식 작용등의 선천 면역은 이루어지나 macrophage에 의한 MHC class II매개의 항원 제시와 apoptosis저하, 항체 생산 관련 유전자의 발현저하가 관찰되어 초기 macrophage에 의한 항원제시의 실패로 적응 면역이 제대로 활성화되지 않아 폐사가 발생한 것으로 사료된다.

• 대한기계학회논문집A
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• 제28권4호
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• pp.453-459
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• 2004

25Cr-20Ni series strainless steels have an excellent high temperature strength high oxidation and high corrosion resistance. However, further improvement can be expected of creep strength by work hardening prior creep. In the present study, the effect of prestraining at room temperature on the creep behavior of a Class M(STS310S) and a Class A(STS310J1TB) alloy containing precipitates have been examined. Prestaining was carried out at room temperature and range of prestrain was 0.5-2.5 % at STS310J1TB and 2.0-7.0% at STS310S. Creep behavior and creep rate of pre-strained specimens were compared with that of virgin specimens. Room temperature prestraining produced the creep life that is longer than that of a virgin specimen both for STS310J1TB and STS310S when creep test was carried out at the temperature lower than recrystallization temperature. The reason for this improvement of creep life was ascribable to the interaction between dislocations and precipitates in addition to the dislocation-dislocation interaction in STS310J1TB and the dislocation-dislocation interaction in STS310S. The beneficial effect of prestraining in STS310J1TB was larger than that of STS310S.

• 한국초등과학교육학회지:초등과학교육
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• 제34권1호
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• pp.123-130
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• 2015

For effective science learning, teachers need to rearrange scientific language so that students can understand the contents with their incomplete language resources. Interlanguage is the interplay between everyday language and scientific language. The purpose of the study was to analyze the patterns of interlanguage during 4th grade science class to learn "Heat and Temperature" and to find the features of meaning sharing inside classroom in which a teacher and students participated. The data analysis shows that elementary students' interlanguage has different features compared to scientific language that involves passive voice and content-specialized nouns. Students' interlanguage implied the quality of class community's knowledge-sharing, according to the degree of how students can connect scientific language and everyday language in more effective ways. The implication to elementary science education was discussed.

• 한국초전도ㆍ저온공학회논문지
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• 제16권2호
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• pp.47-53
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• 2014

In this paper, the general electromagnetic design process of a 10-MW-class high-temperature superconducting (HTS) synchronous generator that is intended to be utilized for large scale offshore wind generator is discussed. This paper presents three-dimensional (3D) electromagnetic design proposal and electrical characteristic analysis results of a 10-MW-class HTS synchronous generator for wind power. For more detailed design by reducing the errors of a two-dimensional (2D) design owing to leakage flux in air-gap, we redesign and analyze the 2D conceptual electromagnetic design model of the HTS synchronous generator using 3D finite element analysis (FEA) software. Then electrical characteristics which include the no-load and full-load voltage of generator, harmonic contents of these two load conditions, voltage regulation and losses of generator are analyzed by commercial 3D FEA software.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2012년도 전기공동학술대회 논문집
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• pp.204-204
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• 2012

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2015년도 추계학술대회
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• pp.130-132
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• 2015

The IMO Polar Code was adopted by Res.MSC.385(94) and Res.MEPC.264(68) and will enter into force on 1 January 2017. The Polar Code will affect design and equipment of ships intending to operate in polar areas. In this study, the requirements in the Polar Code are analysed from the perspective of class.

• International Journal of Concrete Structures and Materials
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• 제10권1호
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• pp.39-46
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• 2016

In this study, different proportions of glass beads used for road marking were added into the concrete samples to reduce the temperature gradient through the concrete pavement thickness. It is well known that decreasing the temperature gradient reduces the risk of thermal cracking and increases the service life of concrete pavement. The extent of alkali-silica reaction (ASR) produced with partial replacement of fine aggregate by glass bead was investigated and compressive strength of concrete samples with different proportion of glass bead in their mix designs were measured in this study. Ideal results were obtained with less than 0.850 mm diameter size glass beads were used (19 % by total weight of aggregate) for C30/37 class concrete. Top and bottom surface temperatures of two different C30/37 strength class concrete slabs with and without glass beads were measured. It was identified that, using glass bead in concrete mix design, reduces the temperature differences between top and bottom surfaces of concrete pavement. The study presented herein provides important results on the necessity of regulating concrete road mix design specifications according to regions and climates to reduce the temperature gradient values which are very important in concrete road design.