• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1704-1706
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• 1999

$YBa_2Cu_3O_x$ superconducting thick film was fabricated by surface diffusion process of $Y_2BaCUO_5$ and the mixed compound of $(3BaCuO_2+2CuO)$ expected to be liquid phase above the peritectic temperature of YBa2Cu30x. For the surface diffusion. 3BaCu02+2CuO mixed with binder material was patterned on $Y_2BaCuO_5$ substrate by the screen printing method. The characteristic of current limit on thick film fabricated was measured. The thick film limited the current from $2.8213mA_{rms}$ to $4.2034mA_{rms}$ with $500{\Omega}$ load resistance, and from $4.1831mA{rms}$ to $4.2150mA_{rms}$ with $10{\Omega}$ load resistance.

• 한국환경과학회지
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• 제27권5호
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• pp.299-308
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• 2018

The adsorption characteristics of Cu ions were studied using the zeolite Na-A synthesized from Jeju volcanic rocks. The effects of various operating parameters such as initial concentration of Cu ions, contact time, solution pH, and solution temperature were investigated in batch experiments. The adsorption of Cu ions by Na-A zeolite was fitted well by pseudo-second-order kinetics and the Langmuir isotherm model. The maximum adsorption capacity determined using the Langmuir isotherm model was 152.95 mg/g. In addition, the adsorption of Cu ions by zeolite Na-A was primarily controlled by particle diffusion model in comparison with the film diffusion model. As the temperature increased from 303 K to 323 K, ${\Delta}G^o$ decreased from -2.22 kJ/mol to -3.41 kJ/mol, indicating that the adsorption of Cu ions by Na-A zeolite is spontaneous process.

• 한국환경과학회지
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• 제25권11호
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• pp.1485-1491
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• 2016

PSf/D2EHPA/CNT beads were prepared by immobilizing di-(2-ethylhexyl)-phosphoric acid (D2EHPA) and carbon nanotubes (CNT) on polysulfone (PSf) and used to remove Cu(II) from aqueous solutions. Optimum pH was in the range of 4 to 6. The removal kinetic of Cu(II) by the prepared PSf/D2EHPA/CNT beads was mainly governed by internal diffusion, and the diffusion coefficient of Cu(II) by PSf/D2EHPA/CNT beads was found to be $2.19{\times}10^{-4}{\sim}2.64{\times}10^{-4}cm^2/s$. The Langmuir isotherm model predicted the experimented data well. The maximum removal capacity of Cu(II) obtained from this isotherm was 7.32 mg/g. Calculated thermodynamic parameters such as ${\Delta}G^o$, ${\Delta}H^o$ and ${\Delta}S^o$ showed that the adsorption of Cu(II) ions onto PSf/D2EHPA/CNT beads was feasible, spontaneous and endothermic at 293-323 K.

• 한국주조공학회지
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• 제13권1호
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• pp.42-49
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• 1993

Conventional manufacturing process for cast iron-babbitt metal composite is complicate and bimetallic bonding by centrifugal casting is also difficult because their melting point is largely different and nonmetallic inclusion exists on outer shell. This study is aiming to simplify multistage process by adding Cu-powder as insert metals during cast iron solidification. The variables on fabrication of composite pipe are mold rotating speed and inner surface temperature of outer metal. The optimum temperature range for fusion bonding between cast iron and Cu-layer was $1100^{\circ}C-1140^{\circ}C$ in case of mold rotating speed was 700rpm. When the inner surface of Cu-layer was at $900^{\circ}C$, the value of interfacial hardness between Cu-layer and babbitt metal were higher than Cu-matrix by forming diffusion layer, interfacial products between Cu-layer and babbitt metal are proved to be $Cu_6Sn_5({\eta})$by XRD.

• 소성∙가공
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• 제6권2호
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• pp.136-144
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• 1997

(Ag-10%Ni)/Cu clad metals for electric contact switch were fabricated by cold-roll bonding process. 2 or 3 passes of cold-rolling was carried out for each process to investigate the effect of the rolling passes on the bonding property. The effect of the annealing temperature of copper before the cold-roll bonding on the bond strength was also studied. The specimen bonded with copper annealed below 30$0^{\circ}C$ before roll bonding showed good bond strength. This is because high stored energy in copper promoted the short range diffusion and the grain refinement of copper by the static recrystallization increased the degree of the interfacial coherency. The maximum peel strength of clad metals bonded with Cu annealed below 30$0^{\circ}C$ was 120N.

• 한국재료학회지
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• 제16권4호
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• pp.257-263
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• 2006

We have investigated the effect of silver added to Cu films on the microstructure evolution, resistivity, surface morphology, stress relaxation temperature, and adhesion properties of Cu(Ag) alloy thin films deposited on Mo glue layer upon annealing. In addition, pure Cu films deposited on Mo has been annealed and compared. The results show that the silver in Cu(Ag) thin films control the grain growth through the coarsening of its precipitates upon annealing at $300^{\circ}C{\sim}600^{\circ}C$ and the grain growth of Cu reveals the activation energy of 0.22 eV, approximately one third of activation energy for diffusion of Ag dopant along the grain boundaries in Cu matrix (0.75 eV). This indicates that the grain growth can be controlled by Ag diffusion along the grain boundaries. In addition, the grain growth can be a major contributor to the decreased resistivity of Cu(Ag) alloy thin films at the temperature of $300^{\circ}C{\sim}500^{\circ}C$, and decreases the resistivity of Cu(Ag) thin films to $1.96{\mu}{\Omega}-cm$ after annealing at $600^{\circ}C$. Furthermore, the addition of Ag increases the stress relaxation temperature of Cu(Ag) thin films, and thus leading to the enhanced resistance to the void formation, which starts at $300^{\circ}C$ in the pure Cu thin films. Moreover, Cu(Ag) thin films shows the increased adhesion properties, possibly resulting from the Ag segregating to the interface. Consequently, the Cu(Ag) thin films can be used as a metallization of advanced TFT-LCDs.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1999년도 춘계학술발표강연 및 눈문개요집
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• pp.98-98
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• 1999

• 한국자기학회지
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• 제8권2호
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• pp.79-85
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• 1998

e-beam evaporator로 [Ni80Fe20/Cu/Co/Cu] 다층박막을 증착하여 자성층 사이의 교환 결합 상태에 따라 Co를 Ni80Fe20/Cu 계면에 삽입, 자기 저항비와 자기 저항비와 자화 곡선의 변화를 연구하였다. 강자성 결합 및 비 결합에서는, 계면에 Co를 삽입하게 되면, 자기 저한 값이 증가하지만 반강자성 결합에서는 자기 저항 값이 감소하는 경향이 보였다. 이러한 원인은 계면에 삽입되는 Co가 계면 산란을 증가시키는 것 뿐만 아니라 자성층 간의 교환 결합상태를 변화 시키기 때문에 것으로 판단된다. 아울러 계면에 삽입된 Co는 박막의 다층 구조를 30$0^{\circ}C$ 이상까지 유지시키며 이는 Cork 효과적인 확산 장애물(diffusion barrier)역할을 하기 때문으로 판단된다.

• 한국재료학회지
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• 제8권3호
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• pp.206-213
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• 1998

순첨분말에 $(CuNO_3)_2$, $Ni(NO_3)_2)_2$, $(NH_4)_6Mo_7O_{24}$를 이온확산시켜 부분확산합금강분으로 제조하고, Cu, Ni, Mo의 함량에 따른 성형성, 소결성, 기계적특성을 조사하였다. 연구결과 각각 Cu 1.50wt%, Ni 1.75wt%, Mo 0.50wt%일 때, 경도 및 인장강도는 우수하고, 수축률의 변화는 거의 없음을 알 수 있었다. 이러한 결과를 이용하여 Cu 1.50wt%, Ni 1.75wt%, Mo 0.50wt%가 함께 이온확산된 부분합금강분을 제조하여 특성을 조사하고, 스웨덴의 Hoganas사에서 수입되고 있는 부분합금강분(distalloy AB/ sub /)과 성형성, 소결성 및 기계적 특성을 비교하여 분석한 결과 본 연구방법에 의해 제조된 것이 성형성이 우수하고, 소결치수의 변화가 거의 없었으며, 같은 소결밀도 및 소경온도 조건에서 인장강도는 $15~20Kg/\textrm{mm}^2$, 경도는 Hv20-30 더 크고, 열처리 하였을 때도 경도 및 인장강도가 좀 더 양호한 결과를 얻었다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1992년도 춘계학술발표회
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• pp.86-87
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• 1992