• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.633-634
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• 2005

Transparent conducting glasses exhibit high ohmic losses that are apparent in the case of large size Dye Sensitized Solar Cells (DSSCs). In this study, we investigated the impact of current collectors over the efficiency of DSSCs. The Silver current collectors were prepared on both counter electrode and working electrode surface by screen printing method. For long term stability in electrolyte environment and also to avoid the charge recombination, current collectors are protected by sodium silicate overcoat layer. These current collectors were characterized for their microstructure parameters. Also current collector's stability in electrolyte environment has been investigated.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.65-65
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• 2000

Microwave response of intrinsic Josephson junctions in mesa structure formed on HgI2-intercalated Bi2Sr2CaCu2O8+x single crystals was studied in a wide range of microwave frequency. With irradiation of 73${\sim}$76 GHz microwave, the supercurrent branch becomes resistive above a certain onset microwave power. At low current bias, the current-voltage characteristics show linear behavior, while at high current bias, the resistive branch splits into multiple sub-branches. The voltage spacing between neighboring sub-branches increase with the microwave power and the total number of sub-branches is almost identical to the number of intrinsic Josephson junctions in the mesa. All the experimental results suggest that each sub-branch represents a specific mode of collective motion of Josephson vortices generated by the microwave irradiation. With irradiation of microwave of microwave of frequency lower than 20 GHz, on the other hand, no branch splitting was observed and the current-voltage characteristics exhibited complex behavior at hlgh blas currents. This result can be explained in terms of incoherent motion of Josephson vortices generated by non-uniform microwave irradiation.

• Journal of Industrial Technology
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• v.34
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• pp.61-66
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• 2014

Recently, Because the consumption of electricity is increased, having stable electricity supply and diagnosis of the power device is important. In this paper, I propose a diagnostic techniques of the leakage current for switchgear based on LabVIEW NI's. Using the data obtained from the leakage current sensor installed in switchgear panels, in performed continuously diagnosis, notifications and warnings can be the administrator immediately results. It is expected accordingly, the administrator will be able to take prompt action. Using the virtual switchgear with a PXI NI's, war tested the proposed techniques.

• Progress in Superconductivity and Cryogenics
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• v.4 no.1
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• pp.110-113
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• 2002

The high-tc superconducting fault current limiters (SFCL) are studied worldwide to be classified as resistive type or inductive type such as magnetic shielding type and dc reactor type. This Paper deals with an open core type SFCL, a kind of magnetic shielding type SFCL. We manufactured a 30 kVA open core type SFCL. It was modified from the old one with a rated power of 8 kVA. We stacked four superconducting tubes as magnetic shielding material and used the same primary winding as the old one. The experiments were performed with a maximum source voltage of 1 kV. The results show that the fault current in the source voltage of 1 kVrms was reduced to be about 105 Apeak, which was calculated to be about 22 % of the fault current in the system without an SFCL.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.85-86
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• 2008

This paper analyzes the improvement of the power quality by the reduction of the inrush current. We analyze the existing methods and simulate the segragated point-on-wave closing method selected as the proper method. And we attempts to use the resistive type Superconducting Fault Current Limiter(SFCL) to reduce the transformer inrush current. We simulate the various insertion resistances and analyze the voltage drop. All simulation are performed by EMTP. The simulation results show the validity and effectiveness of a SFCL application and the segragated point-on-wave closing method to reduce the inrush current and improve the power quality.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.3
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• pp.135-139
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• 2004

Nowadays, one of the serious problems in KEPCO system is large fault current which exceeds the SCC(Short Circuit Capacity) of circuit breaker, As the superconductivity technology has been developed, the HTS-FCL(High Temperature Superconductor-Fault Current Limiter) can be one of the attractive alternatives to solve the fault current problem. However, the parameters of HTS-FCL should be designed optimally to have a best performance. Under this background, this paper presents the optimal design method of parameters for resistive type HTS-FCL using stochastic analysis technique.

• Progress in Superconductivity and Cryogenics
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• v.1 no.1
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• pp.28-32
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• 1999

We have performed an EMTDC simulation for the current limiting effects of a superconducting fault current limiter (SFCL). The fault currents in the 154 kV transmission line between the arbitrary S1 and S2 substations increased up to 54 KA and 60 KA during the line-to-line and three phase faults, respectively. The SFCL with 100$\omega$ of resistance after quench limited the currents to less than 17 KA within a half cycle. This limited current is well below the upper limit of a circuit breaker, suggesting that the resistance of the SFCL in the transmission line is sufficient.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.95-97
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• 1995

A superconducting current generator, or a superconducting rectifier(SCR) is used as a current source to energize a superconducting magnets in SMES, MRI. We selected a full-wave SCR among various SCR models and analyzed its operational characteristics by computer simulation. In process of pumping the current, the improvement of performance is dependent on how much bigger the open resistance of the switch is in comparison to load coil impedance when one of two switches become active. Faster transfer can he seen in resistive commutation mode by shortening the time elapsed for the resistance to arrive at certain level from zero state. Although recovery time for the switch has no direct effect on current pumping, optimal switch design is needed to increasing operational frequency.

• Progress in Superconductivity and Cryogenics
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• v.23 no.2
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• pp.19-23
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• 2021

We have studied the breaking system that combines a resistive superconducting fault current limiter (SFCL) and a DC circuit breaker for DC fault current. To verify the design of the 15 kV DC SFCL, which was driven from the previous work, a 500 V DC system was built and a scale-down SFCL were manufactured. The manufactured SFCL module was designed as a bifilar coil which is a structure that minimizes inductive reactance. The manufactured SFCL module has been experiment to verify characteristics of the current-limiting performance in the DC 500 V system. Also, the manufactured FCL module was combined with the DC circuit breaker to be experimented to analyze the breaking performance. As a result of the experiment, when SFCL was combined to the DC circuit breaker, the energy dissipation received by the DC circuit breaker was reduced by up to 84% compared to when the DC circuit breaker operates alone. We are preparing methods and experiments for the optimal method for much higher performance as a future work.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.207-209
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• 2007

For proper application of the superconducting fault current limiter(SFCL), the prior investigation of fundamental characteristics and its effects to the distribution systems are needed. The Current limiting behavior of SFCL is dominated by quenching and recovery characteristics. So, we have developed an EMTP/ATPDraw model of resistive type SCFL using MODELS language. The operating characteristics and current limiting behaviors of SFCL in distribution systems have been simulated and investigated.