• Proceedings of the KIEE Conference
• /
• 1999.07a
• /
• pp.250-252
• /
• 1999

It is certain that the power qualify will be very important at 21 century. Especially instant power shortage or power fault will occur serious problems. Accordingly stable power supplication is very technical problem. There are many way to make stable supplication as auxiliary generator, but this is long time delay complement. To solve this problem the superconducting magnetic energy storage is introduced. High Tc superconductor is more commercial.

• Korean Journal of Materials Research
• /
• v.6 no.6
• /
• pp.555-560
• /
• 1996

The vibrational behavior and the molecular dynamics of the high Tc superconductor Ba0.6K0.4BiO3 have been studied experimentally and by atomistic computer simulation methods. For Ba0.6K0.4BiO3, the vibrational spectrum is dominated by oxygen ion modes from 150cm-1 to 820cm-1 including infrared absorption bands at 330, 480, 640 and 830cm-1including infrared absorption bands at 330, 480, 640 and 830cm-1at room temperature. Band assignments are discussed in relation to those bands predicted by simulations, and the infrared and Raman measurements reported in the literature.

• Korean Journal of Materials Research
• /
• v.7 no.5
• /
• pp.431-433
• /
• 1997

We investigated a double ring resonator(DRR)device to improve the resonating Q value of a superconductor resonator. To make a DRR device, we made a large area YBCO film on a MgO substrate by pulsed laser deposition(PLD). Thetransition temperature was 88 K and the film was uniformly deposited. We also deposited 500$\AA$SrTiO$_{3}$on the YBCO thin film to protect the superconducting properties from degradation. The loaded Q value was measured as 50000 from simulation and as 2000 from experiment near 10GHz at 77K.

• Journal of the Korean Ceramic Society
• /
• v.26 no.3
• /
• pp.395-401
• /
• 1989

The concentrations of Cu(II), Y(III) and Ba(II) ionic species in aqueous solution due to the formation of Cu2+-oxalate-complex have been theoretically calculated with respect to pH and their solubility diagrams could be obtained. It was verified from the calculation that the excess of Cu2+ and Ba2+ should be added in order to obtain oxalate coprecipitates with the molar ratio of Y : Ba : Cu=1 : 2 : 3. The exact amount of excess species has been calculated with respect to the initial concentrations of metal ions and pH.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1992.05a
• /
• pp.58-63
• /
• 1992

Effects of the second sintering process on the superconducting characteristics of the (Bi, Pb)SrCaCuO system have been studied. It was found that the optimal calcining temperature of mixed powder may be proper to 820$^{\circ}C$ and the optimal sintering temperture was determined on 845$^{\circ}C$. The 2212 phases transitioned the 2223 phasses during the sintring process and zero resistance was attained at 108 K for the samples sintered for 264 hr. The 2223 phases changed into the 2212 phases and nonsuperconducting phases by the second grinding process. And the 2223 phases did not recover easily by the second sintering process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1990.10a
• /
• pp.36-38
• /
• 1990

In this study, a new sintered specimens of Y$\_$1-x/Sm$\_$x/Ba$_2$Cu$_3$O$\_$y/ is composed by substituting Sm for a part of Y in the YBa$_2$Cu$_3$O$\_$y/ high Tc superconductor, in order to study of making (Y$.$Sm)-Ba-Cu-O system sintered specimens and their characteristics. An their change affected on superconductivity and their characteristics are studied by changing the x range of the composition rate. The resistances of electrical characteristics under the conditions of the composition and the temperature are measured by using Ac four probe method in the procedure of this experiments. And it is confirmed that the Meissner effect from the superconductivity of composed Sm system exists in the range of 0

• Proceedings of the KIEE Conference
• /
• 2005.07b
• /
• pp.1225-1227
• /
• 2005

A Bi-2223 tape has beer developed for power applications such as a fault current limiter, a power cable and a superconducting magnetic energy storage system. In such applications, the Bi-2223 tape carries time varying transport current and in addition experiences time varying external magnetic field. It is well known that the external magnetic field not only causes magnetization loss in the Bi-2223 tape, but also drastically increases transport loss due to a so-called "dynamic resistance". We developed an evaluation setup, which can measure transport loss in external at magnetic fields. Using this equipment, we measured the dynamic resistances for various amplitudes and frequencies of an external ac magnetic field perpendicular to the face in the tape. Simultaneously we investigated the effect of an external ac field on transport loss with different experimental conditions. This paper describes test results and discussions on correlation between the dynamic resistance and the transport loss for the Bi-2223 tape.

• Progress in Superconductivity
• /
• v.8 no.2
• /
• pp.143-151
• /
• 2007

Accurate measurements of the microwave surface resistance (Rs) of high temperature superconductor (HTS) films are important with regard to applications of HTS materials for wireless communications. As the surface resistance values of HTS films are usually extracted from the measured unloaded quality factor ($Q_0$) of resonators made of HTS films, it is essential to measure the resonator $Q_0$ with accuracy. The $TE_{011}\;mode\;Q_0$ of sapphire resonators with the endplates made of $YBa_2Cu_3O_{7-{\delta}}$(YBCO) film on $LaAlO_3$ is measured by using the S-parameter circle-fit method at a frequency of about 19.6 GHz and temperatures of 30 K to 90 K, which is compared with the measured values by using the Lorentzian-fit method. Good agreements are found between the two sets of $Q_0$ values measured by using the two different methods whether the resonator is used in a weak-coupling scheme or a strong-coupling scheme, showing reliability of both methods fur measuring the resonator $Q_0$ accurately. The $Q_0$ of sapphire resonators with a gap between the top plate and the rest of the resonator is also discussed.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.52 no.6
• /
• pp.241-248
• /
• 2003

$Bi_{1.84}Pb_{0.34}Sr_{1.91}Ca_{2.03}Cu_{3.06}O_{10+\delta}$ high $T_{c}$ superconductors containing Ag as an additive were fabricated by a solid-state reaction method. The superconducting properties, such as the structural characteristics, the critical temperatures, the grain size and the image of mapping on the surface were investigated. Samples with Ag and Au of 50 wt% each were sintered at various temperature(820~$850^{\circ}C$). The structural characteristics, the microstructure of surface and the critical temperature with respect to the each samples were analyzed by XRD and SEM, EDS and four-prove methode respectively. The critical temperature showed the result which the Ag additive samples are higher than Au additive samples. The microstructure of the surface showed the tendency which the Ag additive samples become more minuteness than Au additive samples.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.355-356
• /
• 2009

In this paper, we investigated the fault current limiting characteristics according to the increase of voltage in the separates three-phase flux-lock type high-Tc superconducting fault current limiter using YBCO CC. The separated three-phase flux-lock type SFCL consists of single-phase flux-phase type SFCL in each phase. Superconductor was using the YBCO CC. To analyze the current limiting characteristics of a three-phase flux-lock type SFCL, the short circuit experiments were carded out fault such as the triple line-to-ground fault. The experimental result shows that fault current limiting characteristics was improved on the high voltage level.