• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04a
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• pp.88-95
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• 2002

Recent development in the field of RE-Ba-Cu-O (REBCO, RE: Y or rare earth elements) bulk high-Tc superconductors (HTS) is reviewed in the present paper. After the fatal weak link problem of sintered REBCO superconductors has been overcome by melt processing, this field has been greatly advanced during last ten years. The critical current density $J_c$ at 77 K has been enhanced by introducing effective flux pinning sites into the $REBa_2Cu_3O_y$ (RE123) superconducting matrix. Large melt-textured REBCO bulk crystals have been fabricated with the TSMG(top-seeded melt growth) technique. Mechanical properties of REBCO bulks have been improved by using the Ag additive or epoxy resin. Real bulk applications such as current lead, fault current limiter, flywheel energy storage system, magnetic field source, magnetic separation system, and etc., surely come true near future.

• Proceedings of the Materials Research Society of Korea Conference
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• 1997.10a
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• pp.117-117
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• 1997

• Polymer(Korea)
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• v.39 no.2
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• pp.235-239
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• 2015

In this work, we evaluated catalytic activity of LiOH, $Cu(acac)_2$ and n-butyltin hydroxide oxide hydrate in the early stage of the melt transesterification of isosorbide and bisphenol A as diol monomers and diphenylcarbonate for the melt polymerizaiton of polycarbonate. $Cu(acac)_2$ proved to be the most active catalyst for homopolymerization process, while the catalytic activity of LiOH was higher than the others in case of melt copolymerization depending on the catalytic mechanism and chemical structure of catalyst. We suggested that evaluation of catalytic activity can be used for selection of catalyst system in bio-based copolymerization of polycarbonate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.69-72
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• 1999

A Well oriented Bi$_2$re$_2$CaCu$_2$O$\sub$8/(Bi2212) superconductor thick films were formed successfully on a copper substrate by liquid reaction between a Cu-free precursor and Cu tape using method in which Cu-free BSCO powder mixture was printed on copper plate and heat-treated. And we examined the mechanism for the rapid formation of Bi2212 superconducting films from observing the surface microstructure with heat-treatment time. At heat-treatment temperature, the printing layer partially melt by reacting with CuO of the oxidizing copper plate, and the nonsuperconducting phases present in the melt are typically Bi-free phases and Cu-free phases. Following the partial melting, the Bi$_2$Sr$_2$CaCu$_2$O$\sub$8/ superconducting phase is formed at Bi-free phase/liquid interface by nucleation and grows. It was confirmed that the phase colony from the phase diagram of Bi$_2$O$_3$-(SrO+CaO)/2-CuO system is similar to the observed result.

• Proceedings of the Korean Magnestics Society Conference
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• 1993.03a
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• pp.62-63
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• 1993

• Journal of Korea Foundry Society
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• v.17 no.5
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• pp.480-487
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• 1997

Particle reinforced metal matrix composites(MMCs) via a centrifugal spray-cast deposition(CSD) process were fabricated by injecting second phase particles($Al_2O_3$<40${\mu}m$, W<17.3${\mu}m$) into copper melt on the atomizing disc. Compositing modes were investigated by combining microstructures and mathematical modeling between Cu droplets and the reinforced particles injected. The $Cu/W_P$ powders were shown that the W particles penetrate and get embedded in the Cu droplets. It is considered that the W particles composite preferentially in Cu melt on the atomizing disc. On the other hand, the $Al_2O_3$, particles did not penetrate into the Cu droplets on the atomizing disc but get attached in surface of Cu droplets during the flight. It is considered that the compositing may be attained in the flight distance which the relative velocity between Cu droplet and $Al_2O_3$, particle is maximum. The microstructure of the $Cu/W_P$ and the $Cu/(Al_2O_3)_p$ composite preform was strongly influenced by compositing modes of droplets, and after subsequent deposition it was comprised as it is called the dispersed type and the cell type of microstructure, respectively.

• Journal of Korea Foundry Society
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• v.35 no.6
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• pp.141-146
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• 2015

Aluminum-based hybrid parts were fabricated through a compound casting process with Al or Cu inserts which can be used for applications requiring high conductivity. Because the interface stability between the insert and the aluminum matrix is important, the effects of process variables on the interfacial adhesion strength were investigated. Additions of Cu and Mg to Al melt were found to enhance the adhesion strength, though the melt fluidity was slightly deteriorated when a small amount of Mg was added. An isothermal heating process after casting further improved the strength. However AlCu intermetallic compounds formed and their thickness increased during the heating process. As a result, deterioration in the interfacial adhesion strength was observed after an excessive annealing treatment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.6
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• pp.622-625
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• 2022

YBa₂Cu₃O_7-y bulk as a high temperature oxide superconducting conductor has the high critical temperature of 92 K. YBa₂Cu₃O_7-y bulk superconductors have been fabricated by a seeded melting growth. Magnetic properties were studied by using superconductor of melted YBa₂Cu₃O_7-y oxides. It was demonstrated that Y₂BaCuO₅ particles acts as a pinning center which plays an important role on the magnetic properties. The thickness of the upper and lower pellets of the YBa₂Cu₃O_7-y bulk was formed at 40 mm with 55 g of the composition, and the YBa₂Cu₃O_7-y superconductor was manufactured through a heat treatment process. Manufacturing the superconducting bulk, it is possible to improve the pore density of the superconducting bulk by providing a path through which oxygen could be emitted.

• Animal Bioscience
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• v.35 no.3
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• pp.484-493
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• 2022

Objective: This study was conducted to evaluate the effects of the supplementation of diets of broiler chickens with hot-melt extruded CuSO₄ (HME-Cu) on their growth performance, nutrient digestibility, gut microbiota, small intestinal morphology, meat quality, and copper (Cu) bioavailability. Methods: A total of 225 broilers (Ross 308), one-day old and initial weight 39.14 g, were weighed and distributed between 15 cages (15 birds per cage) in a completely randomized experimental design with 3 treatments (diets) and 5 replicates per treatment. Cages were allotted to three treatments including control (without supplemental Cu), IN-Cu (16 mg/kg of CuSO₄), and HME-Cu (16 mg/kg of HME processed CuSO₄). Results: The HME-Cu treatment tended to increase the overall body weight gain (p<0.10). The apparent digestibility of Cu was increased by supplementation of HME-Cu at phase 2 (p<0.05). The Escherichia coli count in cecum tended to decrease with the supplementation with Cu (p<0.10). In addition, the HME-Cu treatment had a higher pH of breast meat than the control and IN-Cu treatments (p<0.05). Significant increases in the cooking loss, water-holding capacity, and lightness in the breast were observed in the HME-Cu treatment compared to the control (p<0.05). The Cu content of excreta increased with the Cu supplementation (p<0.05). The concentration of excreta Cu in broilers was decreased in the HME-Cu compared to the IN-Cu in phase 2 (p<0.05). The Cu concentration in the liver was increased with the HME-Cu supplementation, compared with the control diets (p<0.05). Conclusion: This study showed that HME-Cu supplementation at the requirement level (16 mg/kg diets) in broiler diets did not affect the growth performance and the physiological function of Cu in broilers. However, supplementation of Cu in HME form improved the meat quality and the bioavailability of Cu.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.3
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• pp.231-237
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• 2003

RE(Nd, Sm) elements doped (RE/Y)$_{1.8}$B $a_{2.4}$C $u_{3.4}$$O_{7-x}$ [(RE/Y)1.8] high $T_{c}$ superconductors were directionally grown by Top Seed Melt Growth(TSMG) process in air atmosphere. The (001)melt-textured N $d_{1.8}$B $a_{2.4}$C $u_{3.4}$ $O_{7-X}$(Nd1.8) seed crystals were used for achieving the c-axis alignment large grains perpendicular to surface of the samples. The (RE/Y)1.8 SEM micrographs of the melt-textured (RE/Y)1.8 samples revealed that the nonsuperconducting (RE/Y)211 inclusions are uniformly distributed in the superconducting (RE/Y)123 matrix except the region very close to the Nd seed crystal. The microstructure and superconducting properties were investigated by XRD, SEM, TEM and SQUID magnetometer. The Melt-textured (RE/Y)1.8 samples showed an onset $T_{c}$=91K and sharp superconducting transition. Also, the magnetization value of the (RE/Y)1.8 samples were compared with those of Y1.8 sample at 77 K. 77 K. 77 K. 77 K.K.