• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.2004-2005
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• 2007

고온 초전도체를 이용한 자속구속형 사고전류제한기는 1차권선과 2차권선을 감는 방향이나 감은 횟수의 비율에 따라서 부하전류용량과 전류제한용량이 다르다. 부하전류용량은 사고 발생 시 최초의 전류 제한 레벨과 밀접하게 관련이 되는데 자속구속형 사고전류제한기에서 최초의 전류 제한 레벨은 인덕턴스에 의해서 결정되기 때문이다. 전류제한용량은 사고전류제한기의 임피던스와 관계된다. 이 논문에서 자속구속형 사고전류제한기의 변압기 특성을 변화시키면서 부하전류용량과 전류제한용량의 변화를 살펴보았다.

• Korean Journal of Optics and Photonics
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• v.1 no.1
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• pp.65-72
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• 1990

Mather type plasma focus system is designed and fabricated, and its electrical behaviors and the ,~haracteristics of the plasma are investigated. The discharge CUlTent is measured with a Rogowski coil, and the external resistance and inductance of the system are found to be $20m\Omega, 0.2{\mu}H respectively from the measured voltage signals and current signals, and discharge inductance, magnetic, and mechanical energy are calculated. 'i'he speed of the plasma current sheath in the acceleration phase is found to vary as $P^{-0.25}\timesV^{0.38}$ and its value is about is 106 cm/sec. The electron temperature in the plasma is determined from the measurement of the X-ray transmittance with the number of X-ray filters and its value is found to be about I keY. The size of plasma, measured using X-ray pin-hole camera, is about 17 (dia.) x 30 (length)mm2. h)mm2.

• Journal of the Korean Vacuum Society
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• v.15 no.4
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• pp.380-386
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• 2006

In this study, we had designed and fabricated the plasma focus device which can generate the light source for EUV(Extreme Ultra Violet) lithography. And we also have investigated the basic electrical characteristics of currents, voltages, resistance and inductance of this system. Voltage and current signals were measured by C-dot and B-dot probe, respectively. We applied various voltages of 1.5, 2, 2.5 and 3 kV to the anode electrode and observed voltages and current signals in accordance with various Ar pressures of 1 mTorr to 100 Torr in diode chamber. It is observed that the peak values of voltage and current signals were measured at 300 mTorr, where the inductance and impedance were also estimated to be 73 nH and $35 m{\Omega}$ respectively. The electron temperature has been shown to be 13000 K at the diode voltage of 2.5 kV and this gas pressure of 300 mTorr. It is also found that the ion density Ni and ionization rate 0 have been shown to be $N_i = 8.25{\times}10^{15}/cc$ and ${\delta}$= 77.8%, respectively by optical emission spectroscopy from assumption of local thermodynamic equilibrium(LTE) plasma.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.1
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• pp.8-18
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• 2000

We presented a BGA(Ball Grid Array) package for RF circuit modules and extracted its electrical parameters. As the frequency of RF system devices increases, the effect of its electrical parasitics in the wireless communication system requires new structure of RF circuit modules because of its needs to be considered of electrical performance for minimization and module mobility. RF circuit modules with BGA packages can provide some advantages such as minimization, shorter circuit routing, and noise improvement by reducing electrical noise affected to analog and digital mixed circuits, etc. We constructed a BGA package of ITS(Intelligent Transportation System) RF module and measured electrical parameters with a TDR(Time Domain Reflectometry) equipment and compared its electrical parasitic parameters with PCB RF circuits. With a BGA substrate of 3${\times}$3 input and output terminals, we have found that self capacitance of BGA solder ball is 68.6fF, and self inductance 146pH, whose values were reduced to 34% and 47% of the value of QFP package structure. S11 parameter measurement with a HP4396B Network Analyzer showed the resonance frequency of 1.55GHz and the loss of 0.26dB. Routing length of the substrate was reduced to 39.8mm. Thus, we may improve electrical performance when we use BGA package structures in the design of RF circuit modules.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.4
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• pp.616-624
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• 2006

In this paper, the transfer characteristics of high frequency transmission line having defected ground structure (DGS) and lumped elements are described. When a DGS, which is a kind of periodic structure, is inserted into a transmission line, its equivalent inductance and capacitance elements are added to the characteristics of the standard transmission line. This generates resonance, 3dB cut-off frequency, low-pass, band rejection, and band pass characteristics, and causes a slow-wave and enlarged electrical length of the transmission line. In addition, if the DGS is combined by a lumped element such as resistor, capacitor, and inductor, the resonant and cut-off frequencies moves up or down and other changes occur in the transmission characteristics. The variation of the transmission characteristics is described with the qualitative prediction and measured data.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.7
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• pp.834-838
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• 2007

A coupled-defected ground structure(C-DGS) having closely-located DGS cells is proposed for high performance bandstop filter applications. The negative coupling of ground currents between adjacent DGS cells greatly improves the stopband characteristics. We have measured the attenuation slope of 110.8 dB/GHz and -20 dB rejection band from 3.8 GHz to 15.5 GHz. Compared to the double-plane BSF, the proposed BSF improved the sharp cutoff response 7.6 times. We expect the C-DGS be helpful to improve the performance of DGS application circuits and also to extend the possible DGS applications.

• Journal of the Korean Magnetics Society
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• v.25 no.2
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• pp.58-65
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• 2015

This paper deals with the generating characteristic analysis of permanent magnet linear generator (PMLG) with double-sided Halbach magnet array mover and three phases concentrated stator windings by using analytical method. On the basis of a magnetic vector potential and Maxwell's equations, governing equations are obtained, and magnetization modeling for Halbach magnet array is performed analytically by using the Fourier series. And then, we obtain electrical parameters such as back-EMF constant, resistance, and coil inductance based on magnetic field calculations. Finally, analytical results for generating performance are confirmed by comparing with finite element analysis results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3474-3481
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• 2013

In this work, a new high frequency transmission line structure combined with defected ground structure (DGS) and artificial dielectric substrate (ADS) structure is proposed. DGS patterns give add the additional inductance to transmission lines and results in the increased characteristic impedance for a given line width. To the contrary, ADS presents increased capacitance and reduced line impedance. So both play a role in reducing the length of transmission lines commonly, but in preserving the line impedance complementarily. This means that the length of transmission lines can be reduced furtherly by DGS and ADS without a critical change of line width compared to the cases when one of DGS and ADS is used only. As examples, $35{\sim}100{\Omega}$ transmission lines having DGS and ADS are designed, fabricated, measured, and compared to the simulation results. A good agreement between the simulated and measured line impedances is presented. In addition, the physical lengths of the proposed transmission lines are only 55.4~76.9% of those of the normal microstrip lines for the same electrical lengths.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.8
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• pp.107-112
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• 2007

The flux-lock type SFCL consists of transformer with primary and secondary windings connected to a superconducting element in serial. It can be divided into the subtractive and the additive polarity windings according to the winding direction. It could change the fault current limiting characteristics according to the inductance ratio between the coil 1 and coil 2. We investigated the voltage-current characteristics of the flux-lock type SFCL according to the increment of applied voltage. When the applied voltage of the SFCL with the subtractive and the additive polarity windings was increased a initial limiting current ($I_{ini}$) and the quench time of the superconducting element were increased. The recovery time of the superconducting element was increased by increment of applied voltage. Therefore, it was confirmed that recovery characteristics in the flux-lock type SFCL were largely dependent on the consumed energy of a superconducting element because of increment of the consumption power into the superconducting element.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.9
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• pp.791-799
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• 2016

This paper presents the design of reconfigurable frequency selective surfaces for X-band bandpass operation with improved isolation. The proposed reconfigurable FSS is composed of a four-legged loaded element, a inductive stub and a bias grid. The PIN diode is located between the four-legged loaded element and the stub, which can control the frequency response of reconfigurable FSS by ON/OFF state. By adjusting the length of the stub, the desired bandpass frequency and the improved isolation between ON and OFF state can be obtained. For validation of simulated results, we have carried out transmission characteristic measurements using rectangular waveguide of WR-90. The measured results are in good agreements with the simulated results.