• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.5
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• pp.795-801
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• 1994

The BiPbSrCaCuO superconductor was fabricated by diffusion of The dual layer composed of SrS12TCaS11TCuS12TOS1xT in upper layer and BiS12TPbSI0.3TCuS12TOS1yT in lower layer, and varified growh-mechanism of BiPbSrCaCuO superconducting phase. And, we produced optimum conditions of spread volume and each stage of sintering time were upper layer:Lower layer=1:0.2, 1:0.4, 1:0.6 and 24hr., 120hr., 210hr. From the result, the optimum conditions are spread volume(Upper layer:Lower layer=1:0.6), sintering time(210hrs.) at 820$^{\circ}C$.The BiPbSrCaCuO superconductor, fabricated optimum condition, showed zero resistance at critical temperature of 70k.

• Korean Journal of Materials Research
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• v.8 no.3
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• pp.274-279
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• 1998

Optimum Cu and Mn contents in 0.05wt%C-Cu bearing hot rolled steel sheets were investigated by vickers hardness measurement, tensile test and transmission electron microscopy. It was determined that the optimum Cu and Mn contents were 1.2wt% and 0.75-0.85wt% respectively. It was confirmed by TEM observation that the coarse recipitates were fcc $\varepsilon$-Cu in 0.05%C-1.2%Cu-0.75%Mn-O.O4%Nb steel sheets. The Cu-bearing steel sheets having 780MPa of tensile strength could be fabricated by 10% pre-strain and aging treatment at $550^{\circ}C$ for 30min.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.761-762
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• 2006

W-Cu alloy was very useful material for a heat sink, high electric contact and EDM electrode. Powder injection molding (PIM) is the optimum manufacturing technology to provide W-Cu components with low-cost and high-volume. We used various compositions of tungsten coated copper powders (W-Cu with 10 to 80 wt-% of copper) to manufacture W-Cu components by PIM. The optimum mixing, injection molding, debinding and sintering conditions to provide the high performance W-Cu components were investigated. The thermal and mechanical properties of W-Cu parts by PIM were measured. Finally, we can verify the high performance of W-Cu components by PIM with the tungsten coated copper.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.288-289
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• 2007

In this study, in order to develop low temperature sintering ceramics for multilayer piezoelectric actuator application, PMN-PZN-PZT ceramics were manufactured as a function of the amount of CuO addition and their dielectric and piezoelectric characteristics were investigated. With the amount of CuO addition, the physical characteristics of specimens decreased. The specimens showed the optimum value at 0.5wt%CuO addition. Their optimum values were density=$7.93g/m^3$, ${\varepsilon}_r$=1398, kp=0.560, Qm=1706, $d_{33}$=327pC/N, respectively.

• Korean Journal of Metals and Materials
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• v.49 no.8
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• pp.642-648
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• 2011

This paper describes an experimental study on ultrasonic welding of similar and dissimilar metals. There are optimum welding conditions which are found for welding of Al/Al and Al/Cu. It evaluated weldability using tensile test, SEM observation and EDX-ray analysis. Both ultrasonic welding of Al/Al and Al/Cu have amplitude as the variable factor. Al/Cu welding was examined again with welding time as variable factor to find the best conditions. The more welding time or amplitude increase, the better weldability. The optimum conditions for ultrasonic welding of Al/Al were formed at pressure 0.25 MPa, welding time 0.25 sec, amplitude 90%. Pressure 0.25 MPa, welding time 0.4 sec, amplitude 80% are optimized for Al/Cu ultrasonic metal welding and solid-state diffusion generated by ultrasonic vibration and frictional heat is confirmed at the welded interface.

• Journal of Environmental Science International
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• v.30 no.1
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• pp.57-67
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• 2021

Photocatalytic green energy H2 production utilizing inexhaustible solar energy has been considered as a potential solution to problems of energy scarcity and environmental contamination. However, the design of a cost-effective photocatalyst using simple synthesis methodology is still a grand challenge. Herein, a low-cost transition metal, Cu-loaded one-dimensional TiO2 nanorods (Cu/TNR) were fabricated using an easy-to-use synthesis methodology for significant H2 production under simulated solar light. X-ray photoelectron spectral studies and electron microscopy measurements provide evidence to support the successful formation of the Cu/TNR catalyst under our experimental conditions. UV-vis DRS studies further demonstrate that introducing Cu on the surface of TNR substantially increases light absorption in the visible range. Notably, the Cu/TNR catalyst with optimum Cu content, achieved a remarkable H2 production with a yield of 39,239 µmol/g after 3 h of solar light illumination, representing 7.4- and 27.7-fold enhancements against TNR and commercial P25, respectively. The notably improved H2 evolution activity of the target Cu/TNR catalyst was primarily attributed to its excellent separation and efficiently hampered recombination of photoexcited electron-hole pairs. The Cu/TNR catalyst is, therefore, a potential candidate for photocatalytic green energy applications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.354-355
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• 2007

Process variables for manufacturing the $CuInSe_2$ thin film were established in order to clarify optimum conditions for growth of the thin film depending upon process conditions (substrate temperature, sputtering pressure, DC/RF Power), and then by changing a number of vapor deposition conditions and Annealing conditions variously, structural and electrical characteristics were measured. Thereby, optimum process variables were derived. For the manufacture of the $CuInSe_2$, Cu, In and Se were vapor-deposited in the named order. Among them, Cu and In were vapor-deposited by using the sputtering method in consideration of their adhesive force to the substrate, and the DC/RF power was controlled so that the composition of Cu and In might be 1 : 1, while the surface temperature having an effect on the quality of the thin film was changed from 100[$^{\circ}C$] to 300[$^{\circ}C$] at intervals of 50[$^{\circ}C$].

• Journal of the Korean institute of surface engineering
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• v.55 no.2
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• pp.63-69
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• 2022

Preparing various types of thin films of oxide semiconductors is a promising approach to fabricate efficient photoanodes and photocathodes for hydrogen production via photoelectrochemical (PEC) water splitting. In this work, we investigate the feasibility of an efficient photocathode for PEC water reduction of a p-type oxide semiconductor cupric oxide (CuO) thin film prepared via a facile method combined with sputtering Cu metallic film on fluorine-doped thin oxide (FTO) coated glass substrate and subsequent thermal oxidation of the sputtered Cu metallic film in dry air. Characterization of the structural, optical, and PEC properties of the CuO thin film prepared at various Cu sputtering powers reveals that we can obtain an optimum CuO thin film as an efficient PEC photocathode at a Cu sputtering power of 60 W. The photocurrent density and the optimal photocurrent conversion efficiency for the optimum CuO thin film photocathode are found to be -0.3 mA/cm² and 0.09% at 0.35 V vs. RHE, respectively. These results provide a promising route to fabricating earth-abundant copper-oxide-based photoelectrode for sunlight-driven hydrogen generation using a facile method.

• Textile Coloration and Finishing
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• v.18 no.5 s.90
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• pp.22-29
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• 2006

The purpose of this study was to investigate the dyeability and antibacterial activity on wool fabric dyed with cochineal at variable dyeing conditions. Al, Cr, Fe, Cu and Sn were used as mordants and adsorption was compared with different mordanting methods. The optimum dyeing conditions of wool fabrics were dyeing concentration 2.0%(o.w.s), dyeing temperature $60^{\circ}C$, pH 3 and dyeing time 30 minutes. The pre-mordanting method was preferred for Al and Cr, and the post-mordanting one was preferred for Cu, Sn and Fe to achieve better dyeing. The optimum mordanting conditions of wool fabrics dyed with cochineal were mordanting concentration of 1%(o.w.s), mordanting temperature $60^{\circ}C$, and dyeing time 30 minutes. Wool fabrics dyed with cochineal showed a little antibacterial activity, but it was increased by Cu and Sn mordanting. The light fastness and perspiration fastness of wool fabric treated with cochineal were improved by mordanting.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04c
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• pp.86-90
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• 2008

$CuInSe_2$ thin film were prepared in order to clarify optimum conditions for growth of the thin film depending upon process, and then by changing a number of deposition conditions and heat treatment conditions variously, structural and electrical characteristics were measured. Thereby, optimum process variables were derived. For the manufacture of the $CuInSe_2$, Cu, In and Se were deposited in the named order. Among them, Cu and In were deposited by using the sputtering method in consideration of their adhesive force to the substrate, and the DC/RF power was controlled so that the composition of Cu and In might be 1:1, while the annealing temperature having an effect on the quality of the thin film was changed from $200^{\circ}C$ to $350^{\circ}C$ at intervals of $50^{\circ}C$.