• 전기의세계
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• v.20 no.4
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• pp.5-11
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• 1971

This is a study on the insulation methods of home appliances and wiring devices proper to the new electric distribution system, primary side is 22.9/13.2KV, 3 phase 4 wire multigrounding system and secondary side is 380/220V, 3 phase 4 wire common neutral system. 1800V is determined as the electrical insulation voltage of the functional insulation because the abnormal voltage rise of the neutral line is 1300V. In the case of the functional insulation faults, the following safety methods will be suggested to protect the accidental faults: (a) class I appliance (accessible metal part is earthed), (b) class II appliance (doublly insulated), (c) class III appliance (operates at low voltage source). The mechanisms of the wiring devices are not improved to guarantee for the harmful electric shock but also the electrical insulation voltage is rised to 2000V.

• Fire Science and Engineering
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• v.17 no.2
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• pp.1-5
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• 2003

Recently, the occurrences of electrical fire have been suppressed by a residual current protective devices(RCD), a molded case circuit breaker(MCCB) and a fuse in case of an earth leakage, a short circuit and an over current. But it is impossible for the RCD to break the circuit in the case of the conductor fractures, the failure of pressure contacts on connecting points and the momentary short circuit of low voltage wiring. Therefore, it is require to study the constructive problem of the RCD. In this paper, we have tested the operation characteristics of the RCD according to the R load and R-L load in the conductor fractures, the failure of pressure contacts on connecting points and the momentary short circuit of low voltage wiring.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.2
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• pp.182-187
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• 2008

This paper dealt with the detection algorithm of series arcing, which is a cause of electric fires in low-voltage wiring systems. To find the distinguished electrical features of series arc, we simulated series arcing by the arc generator specified in UL1699. An electric heater, an inverter-controlled vacuum cleaner, and a phase-controlled incandescent lamp were used as loads to generate series arcing. A high-pass filter (HPF) with the low cut-off frequency of 3 kHz at -3 dB was fabricated and applied to separate the series arc signal from the AC voltage source. The experiment showed that the high frequency signal generates randomly during series arcing, and the phase-controlled incandescent lamp produces high frequency pulses even in normal state. In this case, the magnitude, the width, and the randomness of high frequency signal should be analyzed to estimate series arcing precisely.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.37-42
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• 2006

The voltage drop in electrical circuits causes a heat accumulation of wiring. This heat could change the specific character of an insulator and deteriorate the dielectric strength so that it could affect an electric leakage, an electric ant a power failure and a fire caused by the short circuit. Therefore optimal design for voltage drop in electrical wiring became an important factor to ensure the safety and economical efficiency of electrical facilities. So in this paper, I analyzed consequences that voltage drop affects in electrical wiring in multi-distributed system used for low electrical system such as road lights, Building, subway station which needs securities for the public society. And I proposed voltage drops computation program and optimal design to ensure the safety and economical efficiency.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.11
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• pp.498-502
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• 2005

The objectives of this paper are to provide information on the characteristics of the discharge signals in a low-voltage indoor outlet. Most of electrical fires are caused by short circuits, overheating of wires, deterioration and incomplete connection of wiring devices. The last two cases are predictable before the occurrence of fire because of its slow progress. We have simulated the discharge signals caused by the deterioration and incomplete connection of wiring devices using aged outlets. From the experimental data, we could characterize the frequency spectrums of the discharge signals depending on the cases. The higher frequency components of the signal are attenuated by the capacitance and inductance of power lines as the measuring point is getting away from the discharges. Main frequency components of the discharge signal are existent at 600kHz - 1.5MHz in incomplete connections and at 210H7z - 8MHz in deteriorations of the outlet.

• Proceedings of the KIEE Conference
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• 2005.07e
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• pp.12-15
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• 2005

The subject of this research is not only to examine effects on electrical wiring that voltage drops make in low voltage load facilities found in apartments, buildings street lightings, factories, and etc, but also to discuss the voltage drops computation program on distributed random loads to optimize their safety and economy.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.6
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• pp.270-275
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• 2005

In order for the application of the in-vivo endoscopic biopsy, a micromirror which can be driven at a low voltage is required. In this paper, a two-step micromirror composed of bottom electrodes, moving plate and top mirror plate is proposed. Because an electrical wiring of two plates are separated, they can be actuated separately. Therefore, an intermediate moving plate plays an important role in reducing the driving voltage in half. The designed device was fabricated by the surface micromachining. Maximum rotation angle of $6.3^{\circ}$ was obtained by applying DC 48V, while a conventional one-step mirror pulled down at DC 120V. The designed structure can be used in microphotonic applications requiring low driving voltage.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.628-632
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• 2002

Low voltage circuit breakers which interrupt rapidly and raise the reliability of power supply are widly used in power distribution systems. In the paper, it was investigated how much Interrupting capability was improved by correcting the shape of the contact system in molded case circuit breaker(below MCCB), especially arc runner. Prior to the interrupting testing, it was necessary for the optimum design to analyze electromagnetic forces on the contact system, generated by current and flux density. This paper presents both our compuational analysis and test results on contact system in MCCB

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2004.06a
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• pp.26-31
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• 2004

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2004.11a
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• pp.287-291
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• 2004