• 한국초전도학회:학술대회논문집
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• 2007.07a
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• pp.9-9
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• 2007

• 한국초전도학회:학술대회논문집
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• 2007.07a
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• pp.21-21
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• 2007

• Progress in Superconductivity and Cryogenics
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• v.23 no.3
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• pp.1-4
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• 2021

Hydrogen, the lightest and the most abundant element in the universe becomes a mainstay of contemporary condensed matter physics, which is largely because its metallization is regarded as the holy grail of high-pressure physics and it is also due to recent observations of high Tc superconductivity in hydrogen-dense compounds at extremely high pressure. Contemporary static high-pressure technique is not enough to realize the metallization of solid hydrogen and hydrogen-dense compounds may significantly reduce the required transition pressure providing an excellent proxy study. In this brief review, I will introduce recent achievements of high-pressure study in solid hydrogen and hydrides.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.124-128
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• 2000

The high Tc phase disappeared and low Tc phase increased in the substitution of transition elements for Bi ions. The high Tc phase decreased in the substitution of Si and Sn for Bi ions. The high Tc phase increased in the substitution of Sb, As and P which were the same group of Bi for Bi ions. The substitution of P ions was the most effective and then the high Tc phase was formed in large quantity by replacing Bi ions with 30% of P ions.

• Bulletin of the Korean Chemical Society
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• v.9 no.5
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• pp.280-282
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• 1988

The structural, electrical and magnetic properties were investigated for the high-Tc superconductor $YBa_2Cu_3O_{7-x}$, where x was 0.13. The results of temperature dependence of the resistivity and the magnetization in $YBa_2Cu_3O_{6.87}$ whose structure and phase are confirmed by arialysis of X-ray powder diffraction pattern have been reported. A very sharp superconductivity transition appears at 92K in the specimen whose chemical composition is determined from redox titration, strongly suggesting that this specimen consists of a single-phase superconductor. From the results of X-ray diffraction analysis, magnetization curves, levitation and resistance measurements, it is suggested that the observed superconductivity is bulk property in nature and that the $YBa_2Cu_3O_{6.87}$ phase is responsible for the superconductivity of the present reproducible specimen.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.73-76
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• 2000

Superconductivity is key technology for 21st century. To suppress emission of green house effect gas, applied superconductivity is important. In this paper, the current status of superconducting power machines such as generatorand motor are described. Most of all studies are the step of demonstration of idea and possibility. There are large gap between physical idea and actual apparatus. Further collaboration between scientists and engineers has been required.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.85-85
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• 2000

The normal state of high-Tc superconducting materials has been believed to contain important clues to finding the correct mechanism of the high-Tc superconductivity. One example is the existence of pseudogap in the normal state even above Tc, as observed in various measurements such as photoemission spectroscopy and tunneling conductance. In this pseudogap regime the existence of preformed pairs only with local phase coherence has been debated. Recently Choi, Bang, and Campbell[1] have proposed the occurrence of the zero-bias conductance enhancement due to Andreev quasiparticle reflection from the preformed pairs even with the local phase coherence. In this study we examine the zero-bias enhancement of the differential conductance near or slightly above Tc, using c-axis tunneling in mesa structure of Bi2Sr20a0u208+d single crystals. In slightly overdoped samples zero-bias conductance enhancement (ZBCE) has been observed over a range of 2 K above Tc. In contrast, in underdoped samples with Tc${\sim}$72K the ZBCE appears over a range of 5-6 K above Tc, a much wider temperature range than in overdoped samples. This result may pose as positive signs of the existence of prefurmed pairs in the normal state of high- Tc superconducting materials.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.17-17
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• 1999

• 한국초전도학회:학술대회논문집
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• 2007.07a
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• pp.7-7
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• 2007

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.322-325
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• 2002

In this paper, the power-linking device connecting the high-Tc super-conducting(HTS) coil to the power system in the DC reactor type three-phase high-Tc superconducting fault current limiter (SFCL) has been designed. This design was triggered from the concept that the magnetic energy could be exchanged into the electrical energy each other. Ferromagnetic material is used as the path of magnetic flux. The device mentioned above was named Magnetic Core Reactor(MCR). MCR was designed to minimize the voltage drop caused by copper loss. The current density of the conductor was 1.3 A/mm$^2$ and % voltage drop was 2%.