• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.21-22
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• 2008

The increase of fault current due to larger power demand has caused the capacity of power machines in grid to increase. To protect the power system effectively from the increased fault current, the superconducting fault current limiter (SFCL) have proposed one of several countermeasures. Therefore, to introduce SFCL into power distribution system, the position of SFCL in power distribution system is selected among some cases. Each position changes fault current limiting characteristics and SFCL's requirement. In this paper, the characteristics of limiting fault current according to installed SFCL's location in power distribution system.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1000-1002
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• 2003

The characteristics of eddy current sensor has been analyzed by using numerical analysis which is performed by modeling eddy current sensor and analytic object into three-dimension axis-symmetry in this paper. The eddy current sensor is modeled as cylindrical shape with variation of inside and outside diameter and frequency range between 1[kHz] and 1[MHa] for numerical analysis. The value of impendence on eddy current sensor depending on frequency variation was calculated through numerical analysis. The characteristics of eddy current sensor can be studied by normalized impendence which is gained from the calculated impendence. Therefore, sensitivity of eddy current sensor depending on frequency, inside and outside diameter can be known by investigating diameter of half circle impendence and its locus.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.458-459
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• 2007

This paper describes the characteristics of lightning impulse current of ZnO block for transmission line arrester with external gap. The ageing parameters of lightning arresters are impulse current, moisture ingress, temperature ageing and so on. Especially it is important to estimate the change of electrical characteristics by impulse current. Total energy applied to the ZnO arrester each time is $4/10{\mu}s$, 30kA and $2/20{\mu}s$, 10kA impulse current. Before and After the test, the residual voltage variation of varistors passed was below 5%. According to the test, it is thought that the ZnO arrester shows good stability with impulse current test.

• Journal of the Semiconductor & Display Technology
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• v.18 no.2
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• pp.29-31
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• 2019

The ZTO/p-Si thin film was produced and investigated for tunneling phenomena caused by the interface characteristics of the depletion layer. ZTO thin film was deposited and heat treated to produce barrier potentials by the depletion layer. The negative resistance characteristics were shown in the thin film of ZTO heat treated at $100^{\circ}C$, and the insulation properties were the best. Current decreased in the negative voltage direction by nonlinear show key characteristics, and current decreased in tunneling phenomenon by negative resistance in the positive voltage direction. Heat treated at $100^{\circ}C$, the ZTO thin film has increased barrier potential in the areas of the depletion layer and therefore the current has increased rapidly. The current has decreased again as we go beyond the depletion layer. Therefore, tunneling can be seen to make insulation better. In the ZTO thin film heat treated at $70^{\circ}C$ without tunneling, leakage current occurred as current increased at positive voltage. Therefore, tunneling effects by negative resistance were found to enhance insulation properties electrically.

• Journal of Welding and Joining
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• v.20 no.5
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• pp.127-133
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• 2002

In this study, metal transfer characteristics in pulsed current metal inert gas (MIG) welding of aluminum was investigated. Based on the metal transfer characteristics from direct current electrode negative MIG welding, the one drop per one pulse(ODOP) condition was predicted and compared with experimental data. The results indicated that experimental pulse range for the ODOP condition is wider than that predicted from the DCEP MIG welding data. In addition, more stable metal trnasfer behavior was obtained at the higher end of the ODOP condition.

• Electrical & Electronic Materials
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• v.8 no.1
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• pp.27-34
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• 1995

The analysis of nonlinear equivalent circuit and the resonance characteristics of input current and output voltage were simulated, and their electrical properties are discussed in the transverse-type piezoelectric ceramic transformer. The nonlinear resonance characteristics of input current and output voltage showed by the thermal effect due to a higher driving current, the nonlinearity increased greatly as driving current increased. When load resistor was 100[M.ohm.], the nonlinear coefficient was -1.3. The nonlinear resonance curve of input current and output voltage for a variation of input voltage and load resistor agreed with the discussed theory. The output voltage increased nearly proportioned to input voltage when load resistors were below 50[M.ohm.], the voltage step-up ratio decreased when a load resistor was 100[M.ohm.] and their maximum value was 950.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.10
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• pp.931-937
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• 2003

The principle of the superconducting vortex flow transistor (SVFT) is based on control of the Abrikosov vortex flowing along a channel. The induced voltage is controlled by a bias current and a control current, instead of external magnetic field. The device is composed of parallel weak links with a nearby current control line. We explained the process to get an I-V characteristic equation and described the method to induce the external and internal magnetic field by the Biot-Savarts law in this paper. The equation can be used to predict the I-V curves for fabricated device. From the equation we demonstrated that the current-voltage characteristics were changed with input parameters. I-V characteristics were simulated to analyze a SVFT with multi-channel by a computer program.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.215-218
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• 2001

In conventional three-phase rectifiers, it was necessary to use a transformer to obtain low output voltage. In this paper, we propose a new three-phase rectifiers circuit that achieves low voltage by using a very simple circuit configuration that does not have a transformer and does not need any complex control. We also describe the operation principle of the proposed circuit, and derive a theoretical formula for its current waveform. On the basis of this formula it also explores the theoretical input/output current characteristics, theoretical current amplification factor, and theoretical output voltage characteristics of these theoretical values with experimentally obtained input/output current characteristics, current amplification factor, and output voltage characteristics, allowed us to confirm the soundness of our theoretical analyses.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.11
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• pp.1571-1577
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• 2015

A new mixed mode control of constant power and constant current for resistance spot welding inverter is proposed to improve the weld quality. The conventional control scheme adopts constant current or constant power control mode, however, it is not easy to guarantee the high weld quality because of the nonlinear resistance characteristics of the welding point. The proposed method utilizes the nonlinear characteristics by measuring the dynamic resistance in real time. Therefore, it is possible for the welder to be controlled adaptively depending on the welding state. Experimental results show that the proposed control scheme improves the weld quality by 6.8 times compared with the conventional constant current mode control.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.884-886
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• 2005

In this paper, we have investigated characteristics of current-voltage for double gate MOSFET with main gate and side gate. Investigated current-voltage characteristics of channel length changed len호 of channel from 1${\mu}$m to 3${\mu}$m. Also, compare and analyzed characteristics of changed of operation temperature changing current that is dignity. gate voltage could know 2V that is superior than device characteristics of current voltage characteristic in 77K acts in room temperature when approved.