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Superconducting properties of internal tin processed $Nb_3Sn$ superconducting wires (내부확산법으로 제조한 $Nb_3Sn$ 초전도 선재의 초전도 특성)

  • Ha, Dong-Woo;Oh, Sang-Soo;Ha, Hong-Soo;Lee, Nam-Jin;Ryu, Kang-Sik
    • Proceedings of the KIEE Conference
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    • 1999.07d
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    • pp.1556-1558
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    • 1999
  • $Nb_3Sn$ superconducting wires were fabricated in order to investigate the effect of pre-heat treatment for internal tin process. 2 types of Sn reservoir were fabricated. One was arranged one large Sn reservoir in the center of wire, the other arranged several Sn reservoirs inthe wire. Diffusion of Sn is better in the strand divided Sn equally than in the strand had one large Sn reservoir during pre heat-treatment. Critical current was better in the wires divided Sn reservoirs uniformly after whole heat treatment.

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A Study on the Short Circuit Current and Molten Mark Analysis of Polyvinyl Chloride Insulated Flexible Cords (비닐코드의 단락전류 및 용융흔 분석에 관한 연구)

  • Choi, Chung-Seog;You, Sun-Hee;Yoo, Jae-Geun;Shong, Kil-Mok;Kim, Hyang-Kon;Lee, Kyung-Sup
    • Proceedings of the KIEE Conference
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    • 1999.07d
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    • pp.1630-1632
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    • 1999
  • In this paper, we studied the short circuit current and molten mark of polyvinyl chloride insulated flexible cords(VFF). The calory decreased remarkably with increase of current. The surface structure and composition of a strand wire were analyzed by stereoscope, scanning electron microscope (SEM), and energy dispersive x-ray spectroscopy(EDX). The surface of a strand wire showed columnar and void. The intensity of CuL spectrum increased in melted mark.

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An Interpretation of Contextualism as Architectural Theory(1) (맥락주의를 건축이론화 하기 위한 시도(1))

  • Lee, Dong-Eon
    • Journal of architectural history
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    • v.8 no.2 s.19
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    • pp.109-118
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    • 1999
  • The purpose of this paper is to apply Stephen C. Pepper's contextualism to architecture: to interpret the former in the light of architectural theory, and ultimately to liberate architecture from the Western 'Idea' and return it to its context. The major concepts of Pepper used in the paper are quality, texture, spread, change, fusion, strand and context. Pepper's contextualism makes us realize that architecture cannot be separated from its context where human beings, history, neighborhood, and nature are all interpenetrating, and create a quality. Contextualism thus teaches us to make an effort to understand the region where we belong, and to create an architectural device that interrelates form and function of an architecture with its space-time environment, or its strand, texture and context.

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Numerical Simulation of Steel Mixing during Sequential Casting of Dissimilar Grades in the Continuous Caster (연속주조시 강종 혼합에 관한 수치해석적 연구)

  • Cho, M.J.;Kim, I.C.;Kim, S.J.;Park, H.;Lee, S.S.
    • Proceedings of the KSME Conference
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    • 2001.06e
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    • pp.436-443
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    • 2001
  • In order to investigate the mixing of dissimilar grades during the arbitrary grade transition in bloom caster, a computational model has been developed. The model is fully transient and consists of two sub models, which account for mixing in the bloom tundish, mixing in the strand. The developed model was verified using concentration histories measured on 1 : 1 scale bloom tundish water model. The result of numerical model showed good agreement with the experimental results of water model. By using this numerical model, the mixing of dissimilar grades in bloom caster has been simulated. As that result, the characteristics of the steel mixing in the bloom tundish and strand was showed and the amount of the intermixed grade bloom was predicted.

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Lipid Peroxidation Product-Mediated DNA Damage and Mutagenicity

  • Koh, Young-Ho;Yoon, Seon-Joo;Park, Jeen-Woo
    • BMB Reports
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    • v.30 no.3
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    • pp.188-193
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    • 1997
  • Membrane lipid peroxidation processes yield products that may react with DNA to cause mutations. Lipid hydroperoxides from linoleic acid in the presence of transition metal ions caused strand breaks in plasmid DNA. DNA damage induced by reactive aldehydes known to be produced by decomposition of lipid hydroperoxides, such as 4-hydroxynonenal or rnalondialdehyde, was repaired by endonucleases and exonuclease III which resulted in the increase of single strand breaks in DNA. Lipid hydroperoxides as well as malondialdehyde and 4-hydroxynonenal also caused mutations in the pUC18 lacZ' gene when measured as a loss of ${\alpha}-cornplementation$. In conclusion. the lipid peroxidation could be an important intermediary event in DNA damage and mutation by oxidative stress.

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Elementary and Secondary School Teachers' Perspectives of Effective Mathematics Teaching

  • PANG, JeongSuk;KWON, Mi Sun
    • Research in Mathematical Education
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    • v.19 no.2
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    • pp.141-153
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    • 2015
  • This paper compares and contrasts the perspectives of effective mathematics teaching by 135 elementary school teachers, 132 middle school teachers, and 124 high school teachers using a questionnaire in South Korea. All groups of teachers chose in common the teaching and learning strand as the most important for effective mathematics instruction. However, elementary school teachers placed greater importance on the curriculum and content strand than their counterparts did. Elementary school teachers tended to agree more upon the 48 items related to good mathematics teaching than their counterparts did. The similarities and differences among the groups of teachers are expected to provoke discussion of what constitutes high-quality mathematics instruction and how such perspectives may be situated in the socio-cultural context.

Single -portal Subscapualrs tendon repair

  • Choe, Chang-Hyeok;Kim, Sin-Geun;Jang, Ho-Jin;Chae, Seong-Beom
    • The Academic Congress of Korean Shoulder and Elbow Society
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    • 2008.03a
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    • pp.179-179
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    • 2008
  • For a partial tear of the subscapularis tendon, the presenting technique requires only the anterior portal for preparing the footprint and suture management, as well as the subclavian portal for placing the suture anchor and suture hook without inserting a cannula. It provides both a good angle for anchor placement and sufficient space for managing the upper portion of a subscapularis tendon tear. A spinal needle was inserted through the subclavian portal in order to identify the appropriate angle for placing the suture anchor. A 3-mm incision was made for the subclavian portal and a biosuture anchor was placed on the footprint portion of the subscapularis tendon. In order to avoid crowding, each limb of both strands of the biosuture anchor were passed through the tendon- posteromedial side first, and anterolateral side second, using a switching technique with suture hook embedded with no.1 PDS. A suture tie was applied in a reverse sequence (the lateral strand first and the medial strand second) through the anterior cannula using a sliding technique.

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Development of ITER TF Cable-in-Conduit Conductors and Their Characteristics (ITER TF 초전도 도체 개발과 특성)

  • Kim, Hyoung-Chan;Oh, Dong-Keun;Park, Su-Hyeon;Kim, Kee-Man;Bruzzone, P.
    • Progress in Superconductivity
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    • v.10 no.2
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    • pp.108-115
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    • 2009
  • As a participant taking part in the ITER TF conductor R&D program, we developed two toroidal field conductors with variations of conduit thickness resulting in the different void fraction of the conductors. The estimated void fractions of the conductors are 31% and 33%. In this paper we present the details of the TF conductor development and performance test results of them carried out by the measurement of current sharing temperature under cyclic loading. Regarding the conductor development, the internal-Sn-processed $Nb_3Sn$ strand characteristics, strand cabling, twist pitch and characteristics of the conduit materials are presented. For the understanding of the conductor design and performance, the conductor test results are presented and the effect of the conductor design parameters such as void fraction and twist pitch is discussed based on the results.

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Constitutive equations for polymer mole and rubbers: Lessons from the $20^{th}$ century

  • Wagner, Manfred H.
    • Korea-Australia Rheology Journal
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    • v.11 no.4
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    • pp.293-304
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    • 1999
  • Refinements of classical theories for entangled or crosslinked polymeric systems have led to incommensurable models for rubber networks and polymer melts, contrary to experimental evidence, which suggests a great deal of similarity. Uniaxial elongation and compression data of linear and branched polymer melts as well as of crosslinked rubbers were analyzed with respect to their nonlinear strain measure. This was found to be the result of two contributions: (1) affine orientation of network strands, and (2) isotropic strand extension. Network strand extension is caused by an increasing restriction of lateral movement of polymer chains due to deformation, and is modelled by a molecular stress function which in the tube concept of Doi and Edwards is the inverse of the relative tube diameter. Up to moderate strains, $f^2$ is found to be linear in the average stretch for melts as well as for rubbers, which corresponds to a constant tube volume. At large strains, rubbers show maximum extensibility, while melts show maximum molecular tension. This maximum value of the molecular stress function governs the ultimate magnitude of the strain-hardening effect of linear and long-chain branched polymer melts in extensional flows.

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Measurement of electrical resistance at the Nb_{3}$Sn CICC joint fabricated by sub-cable to sub-cable joining (Nb_{3}$Sn 초전도 CICC의 sub-cable to sub-cable 접합 및 접합저항 측정)

  • 이호진;홍계원;김기백;권선칠;김기만
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 1999.02a
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    • pp.89-92
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    • 1999
  • A small scale joint sample of Nb3Sn CICC was fabricated by sub-cable to sub-cable joining. This joint was produced by parallel insertion of one end of each sub-cable into the sub-cable space of the other side of cable, which can decrease the equivalent electrical resistance at the joint is expected to have average properties, dc resistance and ac losses, in view of the shapes of ITER type joint and strand to strand joint. The 3.8nOhm of dc resistance was measured in the range of 10-200A transport current. The normalized resistivity of the joint was about 6.7 $\mu}$Ohm-$^mm{2}$. Considering the normalized resistivity, the full scale joint prepared by sub-cable to sub-cable joining may have similar joint dc resistance with other conventional full scale joints with a shorter joining length.

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