• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.5
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• pp.499-505
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• 2015

The coupling effect of electric fields incident on the biological object is investigated in regards to dosimetry for a wireless power transfer(WPT) system using electromagnetic resonance phenomenon. The internal electric fields induced a biological sphere model exposed to a magnetic dipole are calculated with the finite-difference time-domain(FDTD) method considering both incident electric and magnetic fields, the impedance method considering only incident magnetic fields, and theoretical analysis. The results represent that the electric coupling effect on a biological object nearby the WPT system should be considered to conduct exact dosimetry.

• Journal of Power Electronics
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• v.15 no.4
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• pp.987-993
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• 2015

Wireless power transfer technologies typically include inductive coupling, magnetic resonance, and capacitive coupling methods. Among these methods, capacitive coupling wireless power transfer (CCWPT) has been studied to overcome the drawbacks of other approaches. CCWPT has many advantages such as having a simple structure, low standing power loss, reduced electromagnetic interference (EMI) and the ability to transfer power through metal barriers. In this paper, the CCWPT system with 6.78MHz class D inverter is proposed and analyzed. The proposed system consists of a 6.78MHz class D inverter with a LC low pass filter, capacitor between a transmitter and a receiver, and impedance transformers. The system is verified with a prototype for charging mobile devices.

• 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.

• Journal of Electrical Engineering and Technology
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• v.1 no.2
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• pp.153-160
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• 2006

This paper presents a new compensating system, which consists of a shunt active filter and passive components for mitigating voltage and current disturbances arising from an Electric Arc Furnace (EAF). A novel control strategy is presented for the shunt active filter. An extended method based on instantaneous power theory in a rotating reference frame is developed for extraction of compensating signals. Since voltages at the point of common coupling contain low frequency interharmonics, conventional methods cannot be used for dc voltage regulation. Therefore, a new method is introduced for this purpose. The passive components limit the fast variations of load currents and mitigate voltage notching at the Point of Common Coupling (PCC). A three-phase electric arc furnace model is used to show power quality improvement through reactive power and harmonic compensation by a shunt active filter using the proposed control method. The system performance is investigated by simulation, which shows improvement in power quality indices such as flicker severity index.

• Journal of Power Electronics
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• v.16 no.2
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• pp.805-814
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• 2016

Electric-field coupled power transfer (ECPT) systems have been proposed as an alternative wireless power transfer (WPT) technology in recent years. With the use of capacitive plates as a coupling structure, ECPT systems have many advantages such as design flexibility, reduced volume of the coupling structure and metal penetration ability. In addition, wireless communications are effective solutions to improve the safety and controllability of ECPT systems. This paper proposes a power and signal shared channel for electric-field coupled power transfer systems. The shared channel includes two similar electrical circuits with a band pass filter and a signal detection resistor in each. This is designed based on the traditional current-fed push-pull topology. An analysis of the mutual interference between the power and signal transmission, the channel power and signal attenuations, and the dynamic characteristic of the signal channel are conducted to determine the values for the electrical components of the proposed shared channel. Experimental results show that the designed channel can transfer over 100W of output power and data with a data rate from 300bps to 120 kbps.

• Journal of Power Electronics
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• v.19 no.2
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• pp.519-528
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• 2019

The unified power quality conditioner (UPQC) is an effective custom power device that is used at the point of common coupling to protect loads from voltage and current-related PQ issues. Currently, most researchers have studied series unit and parallel unit models and an idealized transformer model. However, the interactions of the series and parallel converters in AC-link are difficult to analyze. This study utilizes an equivalent transformer model to accomplish an electric connection of series and parallel converters in the AC-link and to establishes a precise unified mathematical model of the UPQC. The strong coupling interactions of series and parallel units are analyzed, and they show a remarkable dependence on the excitation impedance of transformers. Afterward, a feed-forward decoupling method based on a unified model that contains the uncertainty components of the load impedance is applied. Thus, this study presents an adaptive method to estimate load impedance. Furthermore, simulation and experimental results verify the accuracy of the proposed modeling and decoupling algorithm.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1169-1177
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• 2008

The system of the railway signaling using the track transmits the approved speed to the location of a train and it. Referring to the way of transmitting train control information, there are the one transmitting it to the on-board system of a train using the direct track, the another transmitting it establishing an instrument, and the other transmitting an instrument by a railway track. The one is the method using the direct track as a conductor for composing the part of the track and attaining the information controlling a train by transmitting a signal to the track. It is used for the high-speed railway and the subway. The method using the track attains information by transmitting it to returned information, and the on-board system of a train attains it by magnetic coupling. Because many reinforcing bars on the concrete slab track are used, interaction between a rail and a reinforcing bar that is not produced on ballast track is made. Due to the interaction, the electric characteristic of rail is changed. In the current paper, we numerically computed the coupling coefficient between the rail and the reinforcing bar based on the concrete slab track throughout the model related to the rail and the reinforcing bar using the concrete slab track that is used in the second interval of the Gyeongbu high-speed railway, and we defined the coupling coefficient not changed in the electric characteristic of rail in the condition that there is no interaction between the rail and the reinforcing bar.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.110-112
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• 2003

Electric control of eddy coupling offers many new possibilities in process control and other industrial control applications. And a form of speed control for the load is affected for a system driven by costant frequency induction motor. This paper analysis speed-torque characteristic of the eddy-current coupling by using the 3-dimensional analytical method. Characteristic experiment is put into operation for the claw pole type eddy current coupling. Design procedure is presented based on the analysis.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1036-1038
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• 2003

Electric control of eddy coupling offers many new possibilities in process control and other industrial control applications. And a form of speed control for the load is affected for a system driven by costant frequency induction motor. This paper compare speed-torque characteristic of three types of eddy-current coupling by using the analytical method. And characteristic experiment of three types of eddy current coupling is put into operation. And then, this paper will discuss operational and magnetic field characteristic of three types model.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.1
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• pp.27-32
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• 2014

In this paper, PZT piezoelectric ceramic specimens with 4 compositions (Zr/Ti=50/50, 53/47, 56/44, 58/42) in $Pb(Zr,Ti)O_3$ system were fabricated. We studied effects of poling strength and thermal aging on the temperature characteristics of eletromechanical coupling factor k31 of the specimens, which were poled with the DC electric fields, 1.5, 2.5 and 3.5 kV/mm respectively and thermally aged for an hour at $200^{\circ}C$. The eletromechanical coupling factor k31 of the specimen with the composition Zr/Ti= 53/47, nearest to the morphotropic phase boundary decreased the most greatly, irrelevant to the intensity of poling field, due to 1st thermal aging. And the temperature coefficient of eletromechanical coupling factor k31 was (-) in the tetragonal phase composition and (+) in the rhombohedral phase composition, which is reverse in the temperature coefficient of resonance frequency. It is interesting that eletromechanical coupling factor k31 of PZT ceramics is shown to be able to increase as temperature increase in the interval $-20{\sim}80^{\circ}C$.