• Journal of Power Electronics
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• v.17 no.2
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• pp.570-578
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• 2017

This paper proposes a method to stabilize the output voltage of the secondary side of an Inductive Power Transfer (IPT) system through tuning/detuning via a serial tuned DC Voltage-controlled Variable Capacitor (DVVC). The equivalent capacitance of the DVVC changes with the conduction period of a diode in the DVVC controlled by DC voltage. The output voltage of an IPT system can be made constant when this DVVC is used as a variable resonant capacitor combined with a PI controller generating DC control voltage according to the fluctuations of the output voltage. Since a passive diode instead of an active switch is used in the DVVC, there are no active switch driving problems such as a separate voltage source or gate drivers, which makes the DVVC especially advantageous when used at the secondary side of an IPT system. Moreover, since the equivalent capacitance of the DVVC can be controlled smoothly with a DC voltage and the passive diode generates less EMI than active switches, the DVVC has the potential to be used at much higher frequencies than traditional switch mode capacitors.

• Journal of Magnetics
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• v.21 no.3
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• pp.442-449
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• 2016

In this paper, an effective numerical analysis method is proposed for calculating dosimetry of the wireless power transfer system operating low-frequency ranges. The finite-difference time-domain (FDTD) method is widely used to analyze bio-electromagnetic field problems, which require high resolution, such as a heterogeneous whole-body voxel human model. However, applying the standard method in the low-frequency band incurs an inordinate number of time steps. We overcome this problem by proposing a modified finite-difference time-domain method which utilizes a quasi-static approximation with the surface equivalence theorem. The analysis results of the simple model by using proposed method are in good agreement with those from a commercial electromagnetic simulator. A simulation of the induced electric fields in a human head voxel model exposed to a wireless power transmission system provides a realistic example of an application of the proposed method. The simulation results of the realistic human model with the proposed method are verified by comparing it with the conventional FDTD method.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.9
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• pp.67-74
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• 2009

For the surge currents like lightning currents containing high frequency components and the abnormal currents having high frequencies which cause the EMI(Electromagnetic interference) problems for the electronic devices and communication instruments, the linear grounding electrodes have the significantly composite impedance characteristics which are dependent on the frequency of the applied current. The impedance of a grounding electrode is not lowered by expanding the dimension of the grounding electrode, and the length of grounding electrode having the minimum value of the grounding impedance for each condition of frequency and soil characteristics is existent, and it is defined as Critical length. In this paper, the critical lengths for the vertically and horizontally-buried grounding electrodes are calculated by using the distributed parameter circuit model. The propriety of the simulations has been confirmed by comparing the simulated results with the measured results.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.256-260
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• 2001

This paper presents boost and buck and buck-boost DC-DC converter circuit topologies of high-frequency soft switching transition PWM chopper type DC-DC high power converters with a single auxiliary passive resonant snubber. In the proposed boost power converter circuits operating under a principle of ZCS turn-on and ZVS turn-off commutation schemes, the capacitor and inductor in the auxiliary passive resonant circuit works as the loss less resonant snubber. In addition to this, the switching voltage and current peak stresses as well as EMI and RFI noises can be basically reduced by this single passive resonant snubber. Moreover, it is proved that converter circuit topologies with a passive resonant snubber are capable of solving some problems of the conventional hard switching PWM processing based on high-ferquency pulse modulation operation principle. The simulation results of this converter are discussed as compared with the experimental ones. The effectiveness of this power converter with a single passive resonant snubber is verified by the 5kW experimental breadboad set up.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.317-322
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• 2003

A novel three-level DC/DC converter (TLC)for high power applications operating from high input voltage Is proposed. Its switch voltage stress can be ensured to be only one-half of the Input voltage. Nevertheless, since all input voltage is applied to the transformer primary side, it has good turns ratio. The driving method of each module is same as those of the conventional phase-shifted ZVS full bridge PWM converter (PSFB) and the zero-voltage-switching (ZVS) of the leading leg are achieved exactly in the same manner as that of the PSFB. Moreover, its three-level operation can considerably reduce the current ripple through the output inductor and it has no problems of the DC-link voltage unbalance. Therefore, it features a low voltage stress, high efficiency, low EMI, high power density, and small sized filter. To confirm the operation, validity, and features of the proposed circuit, experimental results from a 200W, 600V/DC-48V/DC prototype are presented.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.606-608
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• 1994

This paper presents a low speed (1m/sec) elevator controller with a IGBT inverter (9.5KW). The major engineering problems of this development are noise suppression, thermal-dissipation and reliability improvement. The characteristic marks of this elevator are a single board controller, 40% reduced component, 40% reduced cubic content, EMI filter, vector controlled IGBT inverter.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.2
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• pp.255-265
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• 1999

Recently the necessity of MMIC is increasing because clock frequency goes up by digital data transmission of Gbps class being demanded and the density of circuits gets high for the purpose of lightening and miniaturizing system, owing to the development of ultra high speed. When massing lines in a MMIC and super high speed integrated circuit cause the crosstalk and dispersion of signal, a digital signal is distorted and EMI is occurred. To solve this problems, It is necessary to analyze the equivalent parameters of transmission lines. This paper represent the results of the equivalent parameters of transmission lines for single and hi-level structure by using moment method.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.2
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• pp.84-94
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• 2013

In case when the existing TRIAC phase controlled dimmer is drove for the LED lighting equipments, there are many problems such as the LED flicker in low phase-angles, the acoustic noise and elements damage by increase of the peak voltage in the input filter capacitor, mulfunction by insufficiency of the TRIAC holding current, and the abnormal oscillation by LC resonant. In this paper, we proposes the single-stage quasi-resonant PSR(Primary Side Regulation) PWM converter, and the design, the simulation and experiment are performed. As a result, it could confirm that the proposed PWM converter is the lighting equipments for LED drive which can alternate the existing 60W class incandescent bulbs and it has the high drive performance of the efficiency 80% and over, the power factor 0.95 and over under the normal voltage 220V. Finally, total harmonic distortion(THD) is gratified with a standard[1] of the lighting equipments and the durability is evaluated as the high reliablilty of 150,000 hours and over.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.1
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• pp.43-47
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• 2004

We have been using Moisture Barrier Bags for dry packing of semiconductor packages to prevent moisture from absorbing during shipping. Moisture barrier bag material is required to be waterproof, vapor proof and offer superior ESD (Electro-static discharge) and EMI shielding. Also, the bag should be formed easily to the shape of products for vacuum packing while providing excellent puncture resistance and offer very low gas ＆ moisture permeation. There are some problems like pinholes and punctured bags after sealing and before the surface mount process. This failure may easily result in package pop corn crack during board mounting. The bags should be developed to meet the requirements of excellent electrical and physical properties by means of optimization of their raw material composition and their thickness. This study investigates the performance of moisture barrier bags by characterization of their mechanical endurance, tensile strength and through thermal analysis. By this study, we arrived at a robust material composition (polyester/Aluminate) for better packing.

• The Korean Journal of Health Service Management
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• v.1 no.1
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• pp.90-109
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• 2007

This Study aims to examine the relative importants of various tasks of EMT and to examine knowledge level and problems associated with AED. It is based on the survey of paramedics and rescurers. The instrument by Hoe Sum Lim(1999) was used. as the questionaire for this research. The collected data were analyzed by means of $x^2$ test, t-test, and measured by percents. The results for this study were follows: 1) Among the tasks of EMI, "Basic Life Support" were rated as the most important, followed by "O2 supply" and foreign-body removal from mouth. 2) Some of the lower level of importance in task were Intubation, IV, dextrose infusion of Hypoglycemia, NTG S/L for chest pain, hydration for fluid therapy, brochodilator IV for Bronchial Asthma. 3) Some of the lower level of importance in task were apply of MAST, Vital Sign check and administration of traction & spine immobilization & air splint. 4) The most important reason that the used of AED is delayed is "unclear boundary of treatment directed by medical control".