• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.583-586
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• 2000

A passive RF smart card incorporating a non volatile memory element is powered by inductive coupling to a proximately located RF reader. Therefore, the power consumption in the smart card should be low. In this study, we designed the low power passive RF smart card that is operated at 125kHz to apply to the subway ticket system.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1006-1007
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• 2015

Recent improvement in semiconductor technology make efficient switching possible at higher frequencies, which benefits the application of wireless inductive energy transfer. However, a higher frequency does not alter the magnetic coupling between energy transmitter and receiver. Due to the still weak magnetic coupling between transmitting and receiving sides that are separated by a substantial air gap, energy circulates in the primary transmitting side without being transferred to the secondary receiving side. This paper proposes an analysis on the system efficiency to determine the optimal impedance requirement for coils, rectifier and DC-DC Converter. A novel Boost DC-DC Converter is designed to provide the optimal impedance matching in WPT(Wireless Power Transfer) system for various loads.

• Journal of electromagnetic engineering and science
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• v.10 no.4
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• pp.224-230
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• 2010

Wireless power transmission (WPT) is useful technology in near future. There are some kinds of the WPT technologies, WPT via radio waves, resonance coupling, and inductive. Especially the WPT via radio waves is used for multi-purposes from short range to long range application. However, unfortunately it is misunderstood that it is low efficiency and low power. In this paper, I show the theory of beam efficiency between transmitting antennas and receiving antennas and also show some high efficient applications of the WPT via radio waves. Especially, I pick up a wireless power charging system of an electric vehicle and show the experimental results. I show difference between the theory of beam efficiency and the experimental results of short range WPT. I indicate that reasons of poor beam efficiency in the experiment are (1) change of impedance caused by mutual coupling between transmitting antennas and receiving antennas, (2) oblique direction of microwave power to receiving antennas caused by short distance.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1221-1225
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• 2010

The application of the AC and DC lines on the same transmission tower is an economical and practical approaching that increase the power transmission capacity of an existing transmission corridor. But, In this case, Inductive and capacitive coupling between AC and DC lines on the same tower should be investigated in advance. According to the installation plan of 80kV ${\pm}$60MW bipole HVDC in Cheju, KOREA that will be commissioned until 2011, DC lines will parallely operate with 154kV 2 AC lines in existed 154kV AC 4 lines transmission tower. This paper presents the steady state analysis results about the interaction between 154kV AC and 80kV DC lines in the same transmission tower.

• Corrosion Science and Technology
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• v.6 no.2
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• pp.77-81
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• 2007

Fault current can be discharged from power transmission tower due to lightning or inadvertent contact of crane, etc. Pipelines in proximity to either the source of the ground fault or the substation grounding grid may provide convenient conductive path for the fault current to travel. Inappropriate measures to the neighboring pipelines against the fault current may cause severe damages to the pipes such as coating breakdown, arc burn, puncture, loss in wall thickness, or brittle heat-affected zone. Like inductive and conductive AC coupling, steadily induced fault current right after the coating breakdown can lead to corrosion of the pipeline. In this work, some protection guidelines against fault currents used in the field have been validated through the simulation and analytical method.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.1
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• pp.40-46
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• 2012

This paper presents contactless power supply systems using the Valtchev model in transportation systems. The major drawback of contactless systems is that the efficiency is lower than that of contact systems. The coupling coefficient of the contactless transformer is the most influential parameter on the system efficiency. Here, a new computer model for the contactless transfer system developed in the Korea Railroad Research Institute is presented. Also, simulations of the old model and the new model are compared with the prototype measurement to assure the model validity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.2
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• pp.177-186
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• 2012

In this paper, we propose a design method that the crosstalk of probe connector pins satisfy the limitation of -30 dB. The parameters(inductance and capacitance) were extracted in the grid-structured probe connector pin system, and it is shown that the new parameters are easily calculated with increasing ground pin numbers using the previously calculated parameters. In addition, the crosstalk reduction algorithm by employing more grounds around the signal pin has been suggested, and it is confirmed that the suggested method is quite effective especially for the reduction of inductive couplings. Finally, we suggested the correlation between the pitch and the length of the pins to satisfy the crosstalk limitation of -30 dB with the given number of ground pins, which will be quite useful when design a probe connector pin system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.8
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• pp.24-32
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• 2000

In this paper, we have designed and fabricated a new type power divider to be efficient to a size and electrical performance by folding each quarter-wavelength 70.7 Ω section into a tightly-coupled "meander-line" and inserting a slit. In this type, because of coupling, the electrical phase of quarter -wavelength line and the performance change. For this reason, with the inductive slit and the tuning of quarter-wavelength line length, we have compensated for those. The inductance value of the inserted slit is decided by its width and depth, therefore, we could improve the electrical performance through optimization of inductance. Input and output return losses of the designed power divider were -34.2 dB, -34.3 dB respectively, and isolation was -36.7 dB at 1.75 GHz. Besides, a new design approach reduced occupied substrate area by 3:1 approximately.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.7
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• pp.726-733
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• 2010

This paper propose the printed inverted-F antenna using the coupling feed for the mobile phone. The coupling feed can normally leads the additional capacitances in the antenna, so the high inductive reactance of the antenna can be partly compensated. In this paper, it is shown that the bandwidth of the proposed antenna using the coupling feed is improved at $824{\sim}960$ MHz and $1,710{\sim}2,390$ MHz. Then it is compared with the simple direct feed to confirm the improvement of the bandwidth. The proposed antenna covers GSM850/GSM950/DCS/USPCS/WCDMA/Wibro and has the maximum gain of －$4.794{\sim}1.648$ dBi and shows omnidirectional patterns over the operating bands.

• Journal of Power Electronics
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• v.13 no.4
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• pp.701-711
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• 2013

This paper takes into account the influence of the different impedances of distribution lines on power distribution among inverters when the inverters are paralleled with the droop control method. The impact of distribution lines on the power distribution of inverters can be divided into two aspects. Firstly, since the distributed generators are in low voltage grids, there is resistive impedance in the distribution lines, which will cause control coupling and reduce system stability. The virtual negative resistive impedance of inverters is adopted in this paper to neutralize the resistive element of distribution lines and thus make the distribution line impedance purely inductive. Secondly, after solving the resistive impedance problem, the difference in the inductive impedance value of distribution lines due to the low density of distributed generators will cause an unequal share of reactive power. With regards to this problem, modification is put forward for the droop control strategy to share the reactive power equally. The feasibility of the design is validated by simulation and experimental results.