• Proceedings of the Korean Vacuum Society Conference
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• 2001.02a
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• pp.87-87
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• 2001

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.86.1-86
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• 2003

• 한국초전도학회:학술대회논문집
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• 2009.07a
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• pp.87-87
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• 2009

• Progress in Superconductivity
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• v.1 no.1
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• pp.42-46
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• 1999

A high-temperature superconducting 1.78 GHz bandpass filter, designed for PCS applications, is presented. The structure consists of microstrip pseudo-lumped elements, which enables miniaturization of the filter. A 5-pole microstrip filter could be realized on a 37 mm $\times$ 9 mm $LaAlO_3$ substrate, using double-sided high-temperature superconducting $YBa_2Cu_3O{7-\delta}$ thin film. This filter showed 0.7 % fractional bandwidth, 0.3 dB insertion loss, and 12 dB return loss in the passband at 60 K.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.132-136
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• 2009

Recently, for improvement of the magnetic field of high temperature superconductor (HTS) apparatus, many studies investigating on operating in the range of $20{\sim}65\;K$ with liquid helium or the conducting method using cryocooler are actively reviewed. Also, the cooling method using solid nitrogen as cryogen is being suggested. Since the nitrogen has very large specific heat in solid state, it is expected that it can be operated for a long time without a continuous supply of cooling energy. However, there are still insufficient data on the characteristics of solid nitrogen such as thermodynamic properties and liquid-solid phase change. Especially, there was almost no study done on the electrical insulation properties of solid nitrogen so far. In this study, solid nitrogen to find the electrical characteristics was made by using cryocooler and cryostat, and investigated the flashover discharge and breakdown. The results of this study will be useful as a basic data for electrical insulation design of the HTS system using solid nitrogen as cryogen.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.339-339
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• 2007

Metal coating on ceramic powder has long been attracting interest for various applications such as superconductor where the brittle nature of high temperature ceramic superconductor was complemented by silver coating and metalloceramics where mechanical property improvement was achieved via electroless plating. More recently it has become of great interest in embedded passive device applications since metal coating on ceramic particles may result in the enhancement of the dielectric properties of ceramic-polymer composite capacitors. In our study, nickel ion-containing solution was used for coating commercial capacitor-grade $BaTiO_3$ powder. After filtering process, the powder was dried and heat-treated in 5% forming gas at $900^{\circ}C$. XRD and TEM were utilized for the observation of crystallization behavior and morphology of the particles. It was found that the nickel coating characteristics were strongly dependent on the several parameters and processing variables, such as starting $BaTiO_3$ particle size, nickel source, solution chemistry, coating temperature and time. In this paper, the effects of these variables on the coating characteristics will be presented in some detail.

• Progress in Superconductivity and Cryogenics
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• v.12 no.2
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• pp.9-12
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• 2010

A lamination system using reflow soldering was developed to enhance the mechanical properties of high temperature superconductor (HTS) tape. The laminated coated conductor tape was fabricated using the continuous lamination process. The mean, maximum, and minimum tensile loads in a T-peel test of the laminated coated conductor were 9.9 N, 12.5 N, and 7.6 N, respectively. The critical current ($I_c$) distributions of the non-laminated and laminated coated conductor were compared using anon-contact Hall probe method. The transport $I_c$ nearly matched the non-contact $I_c$; however, some degraded Ic regions were found on the length of 800 cm of laminated coated conductor. We confirmed that the cause of the partially degraded $I_c$ was due to an increase in line tension by (1) solidification induced by a change of composition that usually occurs in molten brass (Cu, Zn) in solder, or (2) non-homogeneity of the thickness of the coated conductor or metal tapes. We suggest that reflow soldering is a promising method for reinforced HTS tape if the controlling solder thickness and lamination guide are modified.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1992.11a
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• pp.35-38
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• 1992

The feasibility of magnetohydrodynamic (MHD) Ship propulsion using superconduction magnets is reviewed in light of recent advances in high-temperature superconducting. The propulsion using a screw propeller in the noise reduction has it's own limitation. The epochal noiseless MHD propulsion method which does not have this disadvantage is studying nowadays. The subject of a marine MHD as propulsion has been examined before and was found to be interesting because of relatively low magnetic flux densities. It is demonstrated that the MHD propulsion is technically interesting with high magnetic flux density. The development of large-scale magnets using the high-temperature superconductors now under development could make it practical to construct submersibles for high-speed and silent operation.

• Progress in Superconductivity and Cryogenics
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• v.2 no.1
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• pp.36-39
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• 2000

The main issues for the power application of high Tc superconducting tape are lower AC loss and higher stability conditions. HTS tape has large stability margin by high heat capacity of superconductor itself and high temperature margin. But, it can be damaged by continuous heat generation at quench point, because normal zone propagation velocity by generating heat is very low. Here, we analyze the quench propagation characteristics using finite element method for BSCCO-2223 HTS tape.

• Electrical & Electronic Materials
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• v.10 no.5
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• pp.425-433
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• 1997

BSCCO thin films have been fabricated by co-deposition at an ultralow growth rate using ion beam sputtering(IBS) method. The growth rates of the films was set in the region from 0.17 to 0.27 nm/min. MgO(100) was used as a substrate. In order to appreciate stable existing region of Bi 2212 phase with temperature and ozone pressure, the substrate temperature was varied between 655 and 82$0^{\circ}C$ and the highly condensed ozone gas pressure(PO$_3$) in vacuum chamber was varied between 2.0$\times$10$^{-6}$ and 2.3$\times$10$^{-5}$ Torr. Bi 2212 phase appeared in the temperature range of 750 and 795$^{\circ}C$ and single phase of Bi 2201 existed in the lower region than 785$^{\circ}C$. Whereas, PO$_3$dependance on structural formation was scarcely observed regardless of the pressure variation. And high quality of c-axis oriented Bi 2212 thin film with T$_{c}$(onset) of about 90 K and T$_{c}$(zero) of about 45 K is obtained. Only a small amount of CuO in some films was observed as impurity, and no impurity phase such as CaCuO$_2$was observed in all of the obtained films.lms.