• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.18-20
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• 2007

A coupling capacitor voltage transformer (CCVT) is used in an extra high voltage power system to obtain the standard low voltage signal for protection and measurement. To suppress the effects of ferro-resonance more effectively, a three winding CCVT is used. This paper proposes an algorithm for compensating the secondary voltage of the three winding CCVT. With the secondary voltage of the three winding CCVT, the secondary and tertiary currents are obtained; the primary winding current is obtained by considering non-linear characteristics of the core; the voltage across the capacitor and the inductor are calculated and then added to the measured voltage to compensate the secondary voltage. Test results indicate that the algorithm can reduce the errors of the three winding CCVT significantly.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.6
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• pp.938-943
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• 2008

Coupling capacitor voltage transformers(CCVTs) have been used in extra or ultra high voltage systems to obtain the standard low voltage signal for protection and measurement. For fast suppression of the phenomenon of ferroresonance, three winding CCVTs are used instead of two winding CCVTs. A tuning reactor is connected between a capacitor voltage divider and a voltage transformer to reduce the phase angle difference between the primary and secondary voltages in the steady state. Slight distortion of the secondary voltage is generated when no fault occurs. However, when a fault occurs, the secondary voltage of the CCVT has significant errors due to the transient components such as dc offset component and/or high frequency components resulting from the fault. This paper proposes an algorithm for compensating the secondary voltage of a three winding CCVT in the time domain. With the values of the measured secondary voltage of the three winding CCVT, the secondary, tertiary and primary currents and voltages are estimated; then the voltages across the capacitor and the tuning reactor are calculated and then added to the measured voltage. Test results indicate that the algorithm can successfully compensate the distorted secondary voltage of the three winding CCVT irrespective of the fault distance, the fault impedance and the fault inception angle as well as in the steady state.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.11
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• pp.63-69
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• 1995

A novel programming architecture for antifuse FPGA(Field Programmable Gate Array) is described. This architecture prevents programming transistors from breakdown which occurs due to high voltage across the transistors during antifuse programming. Extra mask and processes can be avoided using this proposed architecture. To reduce the applied voltage across the terminals of programming transistors, different voltage ranges are supplied to vertical and horizontal tracks; between programming voltage Vp and Vp/2 for vertical tracks and between Vp/2 and 0V for horizontal tracks. Therefore, Maximum voltage across the programming transistors is half of the programming voltage and an designated antifuse can be programmed by applying maximum voltage for vertical track and minimum voltage for horizontal track while others are subjected to voltage difference below Vp/2.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.847-850
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• 1998

This paper proposes a new scheme of FLR for improving corner breakdown voltage. The major difference from the conventional FLR is to build extra rings and floating field plates in the corner region. In this structure the additional field plate and ring have reduced th electric field at the junction in the corner region. Thus it improves the breakdown characteristics which are critical for obtaining high breakdown voltage.

• Journal of the Korean Professional Engineers Association
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• v.10 no.1
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• pp.10-14
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• 1977

In accordance with introducing extra high voltage system, system power plants have to be operated in underexcited condition, which causes temperature rise at the stator end portion of turbine generator. This Paper deals with (1) various elements affecting temperature rise and (2) methods of pre-estimating temperature rise.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.83-85
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• 2003

This paper presents a speed control of permanent magnet synchronous motors (PMSM) using an adaptive integral binary observer without speed and position sensors. In view of composition with a main loop regulator and an auxiliary loop regulator, the binary observer has a property of the chattering alleviation in the constant boundary layer. In order to improve the steady state performance of the binary observer, the proposed adaptive integral binary observer is formed by adding extra integral dynamics to the switching hyperplane equation. The effectiveness of the proposed system is conformed by the experimental results.

• Journal of Power Electronics
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• v.12 no.1
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• pp.208-214
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• 2012

This paper presents a novel approach based on the loci of instantaneous symmetrical components called "Wing Shape" which requires the measurement of three input stator currents and voltages to diagnose interturn insulation faults in three phase induction motors operating under different loading conditions. In this methodology, the effect of unbalanced supply conditions, constructional imbalances and measurement errors are also investigated. The sizes of the wings determine the loading on the motor and the travel of the wings while their areas determine the degree of severity of the faults. This approach is also applied to detect open circuit faults or single phasing conditions in induction motors. In order to validate this method, experimental results are presented for a 5 hp squirrel cage induction motor. The proposed technique helps improve the reliability, efficiency, and safety of the motor system and industrial plant. It also allows maintenance to be performed in a more efficient manner, since the course of action can be determined based on the type and severity of the fault.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.8
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• pp.412-417
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• 2000

TV ghost interference can be described as passive interference by the conducting part of transmission lines. In order to survey this interference from large-sized overhead EHV (extra high voltage) transmission line, TV reception quality was measured in the vicinity of that before and after construction. Instrumentation system was composed of ghost analyzer, TV received field intensity meter, VHF/UHF antennas, TV monitor and so on. The system is installed inside the vehicle. TV field intensity and PDUR (Perceived Desired wave to Undersired wave Ratio) are measured to evaluate TV ghost by using the system and vehicle. As the results, the useful data, which can be used to evaluate the effect of TV ghost interference from transmission lines could be obtained. In this paper, it is shown that the range of TV ghost interference from transmission lines can vary according to the frequency of TV electromagnetic wave, an incidence angle to the line and the other conditiions. At present, we are making efforts to establish a PDUR guideline for transmission lines.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.1041-1043
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• 1997

When a new transmission line is planned to construct, the system voltage and the conductor size of the transmission line should be decided by both economical and technical point of view. This paper presents a methodology to determine the optimal voltage for upgrading the transmission system voltage of existing the extra high voltage grid network by meeting the requirements of the transmission cost minimization as well as technical constraints of thermal limit and stability limit in the transmission line. As a case study, calculated are optimal voltages versus distance and capacity of a practically applicable transmission line with 4 bundles 2 circuits. By this study 400kV was selected as the next higher voltage for the existing 220kV Libyan grid network.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.575-580
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• 2004

The latest equipment automatic Intelligence of digital base done large size equipment appear in succession. That run by voltage electric current(mA, mV, ${\mu}A,\;{\mu}V$) that outline is microscopic of action of accuracy large size equipment of this digital base is bulk. Have received influence that is great in river electric field by installment that use computer. Most of domestic working voltage from service entrance extra-high voltage and working voltage of commercial frequency 60Hz working voltage 220V that use our country outside 1 country in interior of 22.900V for semiconductor use computer use digital installment of appliance as well as various smalls of digital base, middle, large size that safety is these fine voltage electric current that is not enough direct admonition hundred vast damage give can. Also, already act in surge circle and impulse transient phenomena such as several thousands, myriads, strong bit error more than billions time to digital fine electronic circuit by mistake use of using electric facility system of system electric power.