• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1572-1573
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• 2006

This paper presents electrical properties of Zinc Oxide(ZnO) surge arrester blocks under the power frequency AC voltages and various temperatures. The leakage current, $I_{R}-V$ curios and power dissipation for the fine and aged ZnO surge arrester blocks were measured as a function of the temperatures and applied voltages. When the temperature is increased from $50\;[^{\circ}C]$ to $150\;[^{\circ}C]$, the total leakage current significantly increased at the sane applied voltage level. Also, the resistive leakage currents and power dissipation were increased with increasing temperature. The leakage current and power dissipation of the aged ZnO arrester blocks were higher than the fine ZnO arrester blocks.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.62 no.4
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• pp.159-163
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• 2013

In this paper, voltage quality improvement is analyzed in case of Superconducting Fault Current Limiter (SFCL) installed in grounding line of main transformer in power distribution system. First, a resistive-type SFCL model is used. Next, Korean power distribution system is modeled. Finally, when SFCL is installed in the starting point of feeder and grounding line of main transformer, voltage qualities are evaluated according to various fault locations and resistance values of SFCL using PSCAD/EMTDC. The voltage quality results in case of grounding line are compared with the voltage in case of feeder.

• 전기의세계
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• v.26 no.3
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• pp.63-68
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• 1977

In this paper, the theory of pulse frequency modulated DC/DC power converter to obtain constant output voltage for all input voltage changes is discussed. The switch controller consisting of integrator and comparator determines the ON time of power switch-Thyristor-by the error between the load voltage and a load reference voltage. Resulting voltage and current waveforms have been studied theoretically in detail and verified experimentally for a resistive and inductive load condition. State equations for voltages and currents using binary logic variables are computed by digital computer. Comparison of these withe oscillograms obtained from an experimental model shows very close agreement.

• 한국초전도학회:학술대회논문집
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• v.13
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• pp.66-66
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• 2003

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2332-2334
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• 2004

A high bandwidth watt-converter, based on an inexpensive, commercially available, standard IC package, is described that covers a frequency ranges from DC to 100 kHz. The new resistive shunt for a wide-band frequency current measurement of the watt-converter was developed. The converter will use application in accurate power measurement under distorted and high frequency conditions. The advantages of the watt-converter are its simplicity, low cost and fast response time.

• 한국초전도학회:학술대회논문집
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• v.14
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• pp.57-57
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• 2004

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.373-376
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• 2003

A new method measuring soil resistivity in frequency range of 5-500[KHz] using variable frequency inverter was presented, and soil resistivity was analysed by resistive and reactive components on the basis of magnitude and phase of measured ground impedance. The test lead arrangement was proposed to reduce the inductive coupling in test circuit for measuring the soil resistivity. The frequency dependence of soil resistivity was mainly caused by the inductive current flowing through grounding conductors over the frequency of 70[KHz].

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.1
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• pp.24-29
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• 2000

We propose a simple method to control the crystallization depth of amorphous silicon (a-Si) deposited by PECVD or LPCVD during the excimer laser annealing (ELA). Employing the new method, we have formed poly-Si/a-Si double film and fabricated a new poly-Si TFT with vertical a-Si offsets between the poly-Si channel and the source/drain of TFT without any additional photo-lithography process. The maximum leakage current of the new poly-Si TFT decreased about 80% due to the highly resistive vertical a-Si offsets which reduce the peak electric field in drain depletion region and suppress electron-hole pair generation. In ON state, current flows spreading down through broad a-Si cross-section in the vertical a-Si offsets and the current density in the drain depletion region where large electric field is applied is reduced. The stability of poly-Si TFT has been improved noticeably by suppressing trap state generation in drain region which is caused by high current density and large electric field. For example, ON current of the new TFT decreased only 7% at a stress condition where ON current of conventional TFT decreased 89%.

• Transactions on Electrical and Electronic Materials
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• v.6 no.5
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• pp.193-197
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• 2005

We investigated fault current limiting characteristics of the flux-lock type superconducting fault current limiter (SFCL), which consisted of a primary winding and several secondary windings connected in series between $high-T_C$ superconducting (HTSC) thin films. Each YBCO thin film has a 2 mm wide and 42 cm long meander line with 14 stripes of different length. The power imbalance due to the slight difference of Ie between YBCO current limiting elements causes the significant power burden on YBCO element with lower $I_C$. We confirmed from our experiments that the mutual coupling between the primary winding and secondary windings of the flux-lock type SFCL reduced the power imbalance between YBCO current limiting elements compared with the resistive type SFCL connected in series.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.2
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• pp.331-337
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• 1994

The scatting problem by E-polarized plane wave with obique incidence on a tapered resistive strip grating with zero resistivity(perfectly conducting) at strip-edges is analyzed by the method of moments in the spectral domain. Then the induced surface current density on the strip is expanded in a series of Chebyshev polynomials of the second kind. The expasion coefficients are calculated numerically in the spectral domain, the numerical results of the geometric-optical reflection coefficient for the tapered resistivity in this paper are compared with those for the existing uniform resistivity. And the position of sharp variation points in the magnitude of the geometric-optical reflection coefficient can be moved by varying the incident angle and the strip spacing, It is found out that these sparp variation points are due to the transition of higher mode between the propagation mode and the evanescent mode.