• Journal of the Korean Vacuum Society
• /
• v.8 no.3B
• /
• pp.368-375
• /
• 1999

The Maxwell equation and the transformer equivalent-circuit model are applied to a radio frequency planar inductively coupled plasma. The spatial distribution of the vector potential, the magnetic field, and the electric field are obtained analytically. As a result, the plasma current, the mutual inductance between the coil and the plasma, and the self inductance of plasma are found to increase with increasing skin depth. The spatial distribution of absorbed power has maximum where the antenna coil exists, and has a similar profile to that of the induced electric field. The power transfer efficiency is found to increase with increasing gas pressure before a saturation around p+ 20mTorr, while it shows an increase with the plasma density before a slight decrease around a density of $5\times10^{11}/\textrm{cm}^3$.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 2000.02a
• /
• pp.185-188
• /
• 2000

The voltage induced in the superconducting background magnet system is analyzed according to the calculation of self inductance and mutual inductance. The voltage induced by blip and compensation coils of the background magnet system is about 6.4V. In order to charge the main background magnet, the power supply must provide the minimum voltage of 1.1 kV. the compensation coils have an influence on the field distribution. The compensation coils result in the decreasing center field about 2.67%. It can remarkably decrease the ac losses and the voltage on the current leads of the background magnet.

• Proceedings of the KIEE Conference
• /
• 1995.11a
• /
• pp.18-20
• /
• 1995

In this paper we presented a calculation method of leakage inductance in electrical machines. For its accurate calculation the finite element method is applied to the analysis of magnetic field distribution. The self and mutual inductances are derived using the results of the magnetic field analysis and the leakage inductance is easily obtained from these inductances. As numerical examples, we tread a single phase transformer and a rotor slot model of induction motor. In the finite element analysis we used the 2D linear magnetostatic formulation with the first-order triangular element.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.5
• /
• pp.502-507
• /
• 2004

The forward planar transformer, which had power capacity of 300 W, input voltage of 220 V, output voltage of 15 V, and switching frequency of 300 KHz, was designed and manufactured by using the planar core with large effective area and the flat copper leadframes for miniaturization and high efficiency of the switching mode power supply (SMPS). As well as, a forward converter equipped with the above mentioned planar transformer was manufactured and electromagnetic characteristics were investigated. The numerical value of turns for 1st and 2nd winding were 15 and 2 respectively The self inductance of 1st winding was 1.592 mH, very low leakage inductance of 2.7 $\mu$H, and the coupling factor of 0.928 were obtained at switching frequency of 300 KHz. The high efficiency of 88.62 % for the SMPS equipped with planar transformer was obtained at power capacity of 300 W.

• Journal of the Korean Magnetics Society
• /
• v.25 no.1
• /
• pp.27-30
• /
• 2015

In this study, the LC resonators were fabricated with ferrite cores and external capacitors, and then their characteristics were investigated for the purpose of developing new displacement sensor. The frequency dependence of impedance of single resonator was estimated. There were two resonance peaks on the impedance spectrum; one by self inductance and the other by mutual inductance. The resonance frequency was shifted linearly in direct proportion to displacement of the resonator showing the proposed device, a pair of LC resonators, could be used a precision displacement sensor.

• Proceedings of the KIEE Conference
• /
• 1998.11a
• /
• pp.97-99
• /
• 1998

This paper presents a numerical study of the behavior of the transformer winding, when stressed by the standard impulse voltage. The mathematical model of the transformer takes several points into the account. Capacitance of not adjacent winding as well as adjacent winding, eddy current loss caused by self and mutual inductance given as the functions of frequency. Not like the previous approach where calculation of capacitance is performed, in average sense. In this paper, capacitance of both adjacent and not adjacent winding is calculated using the numerical approach(B.E.M.), so they can get the more accurate value of capacitance. Because of frequency dependency of inductance, numerical-laplace-transform technique is required. Finally, to validate this approach, a simple test winding is simulated.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.8 no.3
• /
• pp.454-459
• /
• 2007

In this work, micro-scale, high-performance solenoid-type RF chip inductors utilizing amorphous $Al_2O_3$ core material were investigated. The size of the chip inductors was $0.86{\times}0.46{\times}0.45mm^3$ and copper(Cu) wire with $27{\mu}m$ diameter was used as the coil. High frequency characteristics of the inductance(L), quality factor(Q), impedance(Z), and equivalent circuit parameters of the RE chip inductors were measured and analyzed using an RF impedance/material analyzer(HP4291B with HP16193A test fixture). It was observed that the RF chip inductors with the number of turns of 9 to 12 have the inductance of 21 to 34nH and exhibit the self-resonant frequency(SRF) of 5.7 to 3.7GHz. The SRF of inductors decreases with increasing the inductance and inductors have the quality factor of 38 to 49 in the frequency range of 900MHz to 1,7GHz.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.9
• /
• pp.4101-4106
• /
• 2011

In this study, we propose that the structures of 2-layer spiral planar inductors have a lower spiral coil and via increasing inductance in limited possession are and confirm the frequency characteristics. The structures of inductors have Si thickness of $300{\mu}m$, $SiO_2$ thickness of $7{\mu}m$. The width of Cu coils and the space between segments have $20{\mu}m$, respectively. The number of turns of coils have 3. The performance of spiral planar inductors was simulated to frequency characteristics for inductance, quality-factor, SRF(Self- Resonance Frequency) using HFSS. The 2-layer spiral planar inductors have inductance of 3.2nH over the frequency range of 0.8 to 1.8 GHz, quality-factor of maximum 8.2 at 2.5 GHz, SRF of 5.8 GHz. Otherwise, 1-layer spiral planar inductors have inductance of 1.5nH over the frequency range of 0.8 to 1.8 GHz, quality-factor of maximum 18 at 8 GHz, SRF of 19.2 GHz.

• Journal of Institute of Control, Robotics and Systems
• /
• v.5 no.7
• /
• pp.787-793
• /
• 1999

A self-sensing magnetic suspension system utilizing a LC resonant circuit is proposed by using the characteristic that the inductance of the magnetic system is varied with respect to the air gap displacement. An external capacitor is added into the electric system to make the levitation system be statically stable system, which much relieves the control effort required to stabilize the magnetic suspension system of haying an intrinsic unstable nature. For the realization of the self- sensing magnetically levitated system, an amplitude modulation / demodulation method is used with a positive position feedback controller Experimental results are presented to validate the proposed method.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.51 no.8
• /
• pp.482-492
• /
• 2002

This paper deals with overvoltage stresses in the field circuit of synchronous machine connected to HVDC terminal. A load rejection of the HVDC may cause generator in the station to become self-excited, resulting in a severe system overvoltage. This paper shows that violent field current oscillations can be produced by resonance between the machine inductance and the terminal capacitance. As most conventional excitation system do not allow reverses current, new topology of excitation system to allow reverse current is proposed. the proposed system can limit the rate of rise of terminal voltage during conditions of self excitation. Apart from these simulations, the nature(Magnitude and frequency) of the field transient state is explained mathematically. Finally, the EMTDC program is used for the simulation studies.