• Journal of Welding and Joining
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• v.15 no.1
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• pp.109-115
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• 1997

The arc stability and the metal transfer mode of high deposition GMA welding were investigated using various compositions of shielding gas with two types of filler, ie solid wire and metal cored wire. As for a solid wire, the transfer mode changed from axial spray to rotational spray with increasing wire feed rate (welding current) and the transition current was different with the gas composition. The gas composition also affected the apparent stability of rotating arc. As for a metal cored wire, on the other hand, no transition occurred and thus spray transfer mode could be applied with the welding current over 500A (deposition rate over 300g/min). Looking for the development of high deposition GMA welding process, above results were discussed in two different ways, one is to elevate the transition current, the other is to stabilize the rotational transfer mode.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1727-1732
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• 2010

The Current transformer is classified measuring CT and protective CT for their purpose. The measuring CT is required to retain a specified accuracy over the normal range of load currents, but the protective CT must be capable of providing an adequate output over wide range of fault condition. Therefore, the protective CT must determine the transient performance during fault condition. This paper measured peak instantaneous error of the TPY class CT to determine the transient performance directly and indirectly and studied the test results.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.195-196
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• 2008

Output of wind generators are changed by windy level. The change of the output also affects the amplitude of fault current. And this fault current causes OCR's mal-operation. To solve the problem, this paper adopts that Over Current Relay adapted for Decentralized generator algorithm.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.11
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• pp.2043-2048
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• 2011

High speed drive method for a fuel injector cleaner with current control is presented in this paper. The fuel injector cleaner is used for cleaning the fuel injectors in vehicles when it is clogged with deposit and rust. The fuel injector cleaner cleans the fuel injector by turning on and off the fuel injector rapidly. When the fuel injectors are cleaned, the switching speed is very important. However, when the fuel injector is turned off, the residual current in the fuel injector coil slows down the return action of the plunger in the fuel injector deteriorating performance and speed of the fuel injector cleaner. In this paper, fast turn off operation method of fuel injectors is developed for more effective cleaning. The simulation and experiment results show the validity of the proposed method.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.862-863
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• 2007

In this article, we researched the characteristics of heat transfer of the bimetal for over-current protection device. Bimetal consists of two metals which have a different thermal expansion coefficient. To analyze the heat transfer characteristics, by using a bimetal which has a single metal, we analyzed the temperature distribution when bimetal acts a switch. As usual, heat source is applied to the bimetal. But, in the over-current protection switch, the current become heat source. So, by using the current as source, we performed the magnetic analysis and thermal analysis together.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1350-1352
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• 1995

This paper discribed the characteristic of I-t cross-over-point between current limited-fuse and explusion fuse(Bay-O-Net Fuse) and fuse protection in pad-mounted transformer that was generated internal faults and the short circuit of secondary side(load side). In the I-t cross-over-point, current limited fuse was melted when transient recovery voltage was raised rapidly.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.128-129
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• 2000

The over-critical current behaviors for bare or insulated Bi-222 tapes with different matrix materials have been examined. The result shows that static resistances of the two bare tapes becomes similar for currents above 150 A but different for currents below. In the insulated A tape the first rapid temperature rise occurred around 180 A and eventually burned out about 190A.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.495-496
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• 2007

An Over Current Relayng algorithm using 80c196kc micro processor was realized in this paper. This OCR Algorithm was verified with simulated fault signal. The fault signal was made by EMTP and realized by DOBLE to compare H/W test with S/W test. This simulations showed similar result between H/W and S/W test.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.2
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• pp.130-136
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• 2015

This study describes the structure and operation modes of vertical stabilization (VS) converter for international thermonuclear experimental reactor (ITER) and proposes a protection method. ITER VS converter supplies voltage (${\pm}1000V$)/current (${\pm}22.5kA$) to superconducting magnets for plasma current vertical stabilization. A four-quadrant operation must be achieved without zero-current discontinuous section. The operation mode of the VS converter is separated in 12-pulse mode, 6-pulse mode and circulation current mode according to the magnitude of the load current. Protection measures, such as bypass and discharge, are proposed for abnormal conditions, such as over current, over voltage, short circuit, and voltage sag. VS converter output voltage is controlled to satisfy voltage response time within 20 msec. Bypass operation is completed within 60 msec and discharge operation is performed successfully. The feasibility of the proposed control algorithm and protection measure is verified by assembling a real controller and implementing a power system including the VS converter in RTDS for a hardware-in-loop (HIL) facility.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.1
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• pp.20-26
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• 2009

In this paper, the switching mode conversion type pulse charger by fly-back converter method for lead battery of the solar cell generator equipment is proposed. And we propose the control circuit and design method of insulated switching mode convert type pulse charger by fly-back convert method in the lead battery. The proposed system can minimize the current consumption by digital pulse. Also the proposed system can generate the constant 10[KHz] frequency, transmit the signal with main control system in the power control system. And it supervises the state of lead battery using one chip micro processor. The proposed the switching mode conversion type pulse charger by the fly-back converter method can charge fast and stabilize lead battery with nominal value 12[V], 20[AH]. Also we propose the design procedure of the power control circuit for turn ratio of fly-back inductor and determining method of values such as the charging current, bulk current, partial current, over current value and fixed charging voltage. The experiment results for the voltage and current wave for partial, bulk, over and fixed charging period show the good charging effect and performance. And the PCB and internal coupling diagram of the switching mode conversion type pulse charger by fly-back converter method is presented.