• Journal of IKEEE
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• v.24 no.1
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• pp.368-371
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• 2020

In this paper, we propose a linear tapered slot rectifying antenna for a portable UHF-band RFID system. Since the proposed rectifying antenna does not use a dielectric substrate, the planar antenna is implemented with a thin metal thickness. The rectifier circuit converts input RF power into output DC voltage using a voltage doubler circuit based on two anti-parallel schottky diodes. The rectifying antenna is integrated by the voltage doubler circuit into a linear tapered slot antenna. For conjugate impedance matching of the rectifying circuit and the linear tapered slot antenna, the source-pull method was utilized by adjusting the angle of the tapered slot and the length of the antenna feed line. The proposed antenna prototype has been verified with the electrical and radiation characteristics through RF-DC conversion and far-field radiation test in open space measurement environment. Finally, the proposed antenna is realized to 0.23-wavelength (75 mm) and 0.18-wavelength (60 mm) at 915 MHz center frequency.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.2
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• pp.35-40
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• 1989

In this paper, a new method which simultaneously gives the radiation conductance and susceptance of the rectangular microstrip patch antenna. This solution is derived from the load admittance of the equivalent ${\pi}-$network circuit of the slitted parallel-plate waveguide filled with homogeneous dielectric. Our theoretical results for the radiation admittance are compared with other theoretical results. Also, our theoretical return loss and resonant frequency which are calculated by use of the equivalent transmission line model are in fairly good agreement with the experimental results.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.630-633
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• 1997

This paper describes a design of a single phase PWM converter for high speed train. Parallel operation and control method of four Quadrant PWM converters are described. Simulation and modelling of the converters is performed. Capacity of the converter/inverter and power circuit for high speed traction system designed. And harmonic contents of AC line current's are analyzed. The results of the simulation are presented.

• Journal of Power Electronics
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• v.12 no.2
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• pp.258-267
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• 2012

An interleaved single-stage AC/DC converter with a boost converter and an asymmetrical half-bridge topology is presented to achieve power factor correction, zero voltage switching (ZVS) and load voltage regulation. Asymmetric pulse-width modulation (PWM) is adopted to achieve ZVS turn-on for all of the switches and to increase circuit efficiency. Two ZVS half-bridge converters with interleaved PWM are connected in parallel to reduce the ripple current at input and output sides, to control the output voltage at a desired value and to achieve load current sharing. A center-tapped rectifier is adopted at the secondary side of the transformers to achieve full-wave rectification. The boost converter is operated in discontinuous conduction mode (DCM) to automatically draw a sinusoidal line current from an AC source with a high power factor and a low current distortion. Finally, a 240W converter with the proposed topology has been implemented to verify the performance and feasibility of the proposed converter.

• Proceedings of the KIEE Conference
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• 2002.04a
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• pp.147-150
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• 2002

HPSL(High Pressure Sodium lamp)have attracted much attention in recent years, because they offer high luminous efficiency and very long life. Recently, AC-DC converters have been widely as power factor improvement circuits in the power conversion equipment An application of the ZVT-PWM(Zero Voltage Transition Pulse Width Modulation) boost converter, which has great advantage on miniaturization and high power density, to the power factor improvement circuit of the HPSL inverter are described to identify the power factor correction characteristics of the inverter. In this paper the series-parallel resonant inverter(electronic ballast) for driving a HPS lamp is discussed. Finally, a power factor corrector is cascaded in front of the electronic ballast. Consequently, a high power factor above 0.99 and low THD on the line current can be achieved.

• ETRI Journal
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• v.31 no.6
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• pp.741-748
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• 2009

We present an analysis of microstrip coupled lines (MCLs) used to improve the stability of a 60 GHz narrowband amplifier. The circuit has a 4-stage structure implementing MCLs instead of metal-insulator-metal (MIM) capacitors for the unconditional stability of the amplifier and yield enhancement. The stability parameter, U, is used to compare the stability of MCLs with that of MIM capacitors. Experimental results show that MCLs are more stable than MIM capacitors with the same capacitances as MCLs because the parasitic parallel resistances of MCLs are lower than those of MIM capacitors. Moreover, the bandwidth of an amplifier using MCLs is narrower than one using MIM capacitors because the parasitic series inductances of MCLs are higher than those of MIM capacitors.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1231-1234
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• 1998

Design & Operation of power system for meeting increase of electric power demand is becoming more difficult and complex. One of reasons is increase of fault current. As one of the most effective methods for suppressing the fault current, installation of SFCL is expected. This paper describes a method of fault analyses of power system with SFCLs, and also discusses determination of specification of SFCLs, effects of limiting the fault current due to SFCLs by use of the model system of two - bus electric power system with parallel circuit model transmission line. Also, describes the definition of six specific parameters of SFCL for power system application & a proposal of design method of specific parameter of a resistance type SFCL in overhead transmission lines considering operation of protective relays.

• Korean Journal of Optics and Photonics
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• v.1 no.2
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• pp.169-177
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• 1990

We have constructed the laser system which was consisted of a high voltage pulse poner supply, a rapid high voltage spark gap and the Blumlein transmission line circuit of the multiple parallel plate capacitor type, and have studied the self-preionization effect from this laser system without additional modifications. The value of inductive or resistive loading of the laser oscillator seems to have a significant effect on the preionization. The optimal operational condition of this laser system was obtained at the inductive loading of L = I mtl across the laser tube with the spark gap distance of 6.0 mm. nitrogen pressure of 50 torr, when repetition rate was 70 Hz. Stability was found to be better than 2.0Yo and EIP was 867 V/cm.torr.

• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.358-360
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• 2002

한국전력은 당진화력발전소로부터 신안성 변전소까지의 세계 최초로 수직배열 2회선의 765kV 송전선로를 건설하여 2002년 4월부터 1회선을 765kV로 가압하고 1회선은 345kV로 상업운전을 시작하였으며 2003년 이후 2회선을 모두 765kV 전압으로 가압 예정이다. 이러한 765kV 송전선로는 계통운영 측면에서 2회선 동시 휴전이 어려워 1회선 휴전 작업 및 향후 활선작업이 요구되는 중요선로이다. 765kV 1회선 휴전작업을 위해서는 765kV로 가압된 선로로부터 휴전선로의 작업자에게 발생될 수 있는 전기적 유도량에 대해 사전 검토하여 안전성을 확보하는 것이 필수적이다. 한국전력공사와 전력연구원은 1회선 휴전작업에 대한 안정성 검토를 위해 고창 실증시험선로를 이용하여 전기적 유도현상에 대한 시험을 실시하였다. 이 논문에서는 실증시험 선로를 모델로한 정전유도의 계산 결과와 실측치를 각각 비교, 검토하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.6
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• pp.522-525
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• 2009

We investigated the fault current characteristics of the separates three-phase flux-lock type superconducting fault current limiter(SFCL) according to the variation of inductances. The single-phase flux-lock type SFCL consists of two coils. The primary coil is wound in parallel to the secondary coil on an iron core. And superconductor is series connected on secondary coil. Superconductor is using the YBCO coated conductor. The separated three-phase flux-lock type SFCL consists of single-phase flux-phase type SFCL in each phase. To analyze the current limiting characteristics of a three-phase flux-lock type SFCL, the short circuit experiments were carried out fault such as the triple line-to-ground fault. The experimental result shows that fault current limiting characteristics of additive polarity winding was better than subtractive polarity winding and when the inductances of coil 2 was lower, resistances of YBCO CC was more generated.