• 한국화재소방학회논문지
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• 제18권4호
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• pp.72-77
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• 2004

본 연구에서는 외부화염에 의한 비닐코드의 손상에 따른 단락 진행과정, 외형 및 표면 구조,조성 변화 등 단락 특성을 연구하였다. 초고속이미지시스템(HSIS)을 이용하여 단락과정을 분석한 결과, 열적피로에 의해 피복이 소실되면서 전선 도체가 닿아 수회에 걸쳐 단락이 발생하였으며. 실체현미경과 SEM을 이용하여 외형과 표면구조를 분석한 결과, 전원 측 전선은 두 가닥 모두에 용융흔이 형성되었으며 V자형의 흠을 나타냈다. 부하 측 전선의 용융흔은 전원 측 보다 큼을 알 수 있었다. EDX에 의한 조성분석 결과. 전원 측에서는 Cu와 O가 검출되었으며 부하 측에서는 Cu와 O 이외에 피복재료인 Cl과 Ca를 검출할 수 있었다. 이와 같은 실험과 분석결과를 바탕으로 전기화재의 원인을 규명하는데 많은 도움이 될 것으로 기대한다.

• 한국재료학회지
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• 제15권10호
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• pp.632-638
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• 2005

To investigate the effect of Mo and Cu contents on tensile strength of cold drawn stainless steel 304H wires, metallographical and mechanical tests were performed for the wire specimens drawn to different drawing strains at room temperature. It was confirmed that the contents of Mo ana Cu have little influence on the tensile strength of drawn specimens, even though the strain induced martensite transformation decreased with increasing the contents of Mo and Cu. These results were explained by the strengthening of the formed martensite itself due to the solid solution effect of interstitial solutes, carbon and nitrogen. The contents of these elements were slightly higher in the specimens containing additionally added Mo and Cu.

• 한국분말재료학회지
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• 제14권5호
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• pp.320-326
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• 2007

Ag-Cu alloy nano powders were fabricated by the electrical explosion of Cu-plated Ag wires. Ag wires of 0.2mm diameter was electroplated to final diameter of 0.220 mm and 0.307 mm which correspond to Ag-27Cu and Ag-68Cu alloy. The explosion product consisted of equilibrium phases of ${\alpha}-Ag$ and ${\beta}$-Cu. The particle size of Ag-Cu nano powders were 44 nm and 70 nm for 0.220 mm and 0.307 mm wires, respectively. The Ag-Cu nano powders contained less Cu than average value due to higher sublimation energy compared to that of Ag. As a result, micron-sized spherical particles formed from liquid droplets contained higher Cu content.

• 한국초전도ㆍ저온공학회논문지
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• 제22권2호
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• pp.26-31
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• 2020

Since 2014, Sam Dong Co., Ltd. has successfully developed high-performance MgB₂ superconducting wires with a kilometer-scale. Herein, we studied performances of various MgB₂ wires fabricated by the Sam Dong with different Cu fractions and diameters for practical applications. Critical current densities of our commercial wire, 18+'1'Cu multifilamentary MgB₂ wire, are estimated to be 270,000 A/㎠ at 3 T and 4.2 K and 100,000 A/㎠ at 2 T and 20 K, respectively. We further discuss research progress of various MgB₂ superconducting wires at Sam Dong Co., Ltd and make an effort to align with customers' requirements.

• 전기학회논문지P
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• 제57권3호
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• pp.332-337
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• 2008

We analyzed carbonization pattern and crystal structure of polyvinyl chloride wire by thermal stress. Copper that is oxidized at normal temperature is a reddish brown. If under the thermal stress range of 500 to 700 [$^{\circ}C$], carbonization and exfoliation occurrence. Section structure of electric wire is same as arrangement of particle in metallograph analysis. But, as thermal stress increases, size of particle is enlarged. Electric wire displays elongation structure in SEM image analysis and elongation structure collapses when receive thermal stress at 300 [$^{\circ}C$]. In EDX analysis, we get the spectra of CuL, CuK, OK, and ClK. FT-IR analysis was shown new spectra with in range of $1,440{\sim}1,430\;[cm^{-1}]$, 1,340 [$cm^{-1}$], 1,240 [$cm^{-1}$].

• 한국분말재료학회지
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• 제18권6호
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• pp.546-551
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• 2011

Ag spot-coated Cu nanopowders were synthesized by a hydrothermal-attachment method (HA) using oleic acid capped Ag hydrosol. Cu nano powders were synthesized by pulsed wire exploding method using 0.4 mm in diameter of Cu wire (purity 99.9%). Synthesized Cu nano powders are seen with comparatively spherical shape having range in 50 nm to 150 nm in diameter. The oleic acid capped Ag hydrosol was synthesized by the precipitation-redispersion method. Oleic acid capped Ag nano particles showed the narrow size distribution and their particle size were less than 20 nm in diameter. In the case of nano Ag-spot coated Cu powders, nanosized Ag particles were adhered in the copper surface by HAA method. The components of C, O and Ag were distributed on the surface of copper powder.

• 한국분말재료학회지
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• 제9권2호
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• pp.124-132
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• 2002

Nano Cu powders, synthesized by Pulsed Wire Evaporation (PWE) method, have been compacted by Magnetic Pulsed Cojpaction(MPC) method. The microstructure and mechanical properties were analyzed. The optimal condition for proper mechanical properties with nanostructure was found. Both pure nano Cu powders and passivated nano Cu powders were compacted, and the effect of passivated layer on the mechanical properties was investigated. The compacts by MPC, which had ultra-fine and uniform nanostructure, showed higher density of 95% of theoretical density than that of static compaction. The pur and passivated Cu compacted at $300^{\circ}C$ exhibited maximum hardnesses of 248 and 260 Hv, respectively. The wear resistance of those compacts corresponded to the hardness.

• 한국재료학회지
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• 제27권11호
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• pp.597-602
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• 2017

In this study, an Al-0.7wt%Fe-0.2wt%Mg-0.2wt%Cu-0.02wt%B alloy was designed to fabricate an aluminum alloy for electrical wire having both high strength and high conductivity. The designed Al alloy was processed by casting, extrusion and drawing processes. Especially, the drawing process was done by severe deformation of a rod with an initial diameter of 12 mm into a wire of 2 mm diameter; process was equivalent to an effective strain of 3.58, and the total reduction in area was 97 %. The drawn Al alloy wire was then annealed at various temperatures of 200 to $400^{\circ}C$ for 30 minutes. The mechanical properties, microstructural changes and electrical properties of the annealed specimens were investigated. As the annealing temperature increased, the tensile strength decreased and the elongation increased. Recovery or/and recrystallization occurred as annealing temperature increased, and complete recrystallization occurred at annealing temperatures over $300^{\circ}C$. Electric conductivity increased with increasing temperature up to $250^{\circ}C$, but no significant change was observed above $300^{\circ}C$. It is concluded that, from the viewpoint of the mechanical and electrical properties, the specimen annealed at $350^{\circ}C$ is the most suitable for the wire drawn Al alloy electrical wire.

• 한국분말재료학회지
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• 제15권4호
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• pp.285-291
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• 2008

Fe based ($Fe_{68.2}C_{5.9}Si_{3.5}B_{6.7}P_{9.6}Cr_{2.1}Mo_{2.0}Al_{2.0}$) amorphous powder were produced by a gas atomization process, and then ductile Cu powder fabricated by the electric explosion of wire(EEW) were mixed in the liquid (methanol) consecutively. The Fe-based amorphous - nanometallic Cu composite powders were compacted by a spark plasma sintering (SPS) processes. The nano-sized Cu powders of ${\sim}\;nm$200 produced by EEW in the methanol were mixed and well coated with the atomized Fe amorphous powders through the simple drying process on the hot plate. The relative density of the compacts obtained by the SPS showed over 98% and its hardness was also found to reach over 1100 Hv.

• 한국분말재료학회지
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• 제10권4호
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• pp.275-280
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• 2003

Synthesis and characteristics of Cu nanopowder were considered by in-situ characterization method using SMPS in pulsed wire evaporation process. With increasing pressure in chamber, particle size and degree of agglomeration increased by increase of collision frequency. Also, it was found from the XRD analyses and BET measurements that crystallite size and particle size decreased with elevating applied voltage. However, SMPS measurements and TEM observation revealed the increase of particle size and degree of agglomeration with increase of applied voltage. These results suggested that particle growth and agglomeration depend on overheating factor in chamber at the early stage and thermal coagulation in filtering system during powder formation until collection.