• Journal of Magnetics
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• v.16 no.1
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• pp.51-57
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• 2011

A power supply for magnetic-stimulation devices was designed via a control algorithm that involved a start current application based on a resonant converter. In this study, a new power supply for magnetic-stimulation devices was designed by controlling the pulse repetition frequency and pulse width. The power density could be controlled using the start-current-compensation and ZCS (zero-current switching) resonant converter. The results revealed a high-repetition-frequency, high-power magnetic-stimulation device. It was found that the stimulation coil current pulse width and that pulse repetition frequency could be controlled within the range of 200-450 ${\mu}S$ and 200-900 pps, respectively. The magnetic-stimulation device in this study consisted of a stimulation coil device and a power supply system. The maximum power of the stimulation coil from one discharge was 130 W, which was increased to 260 W using an additional reciprocating discharge. The output voltage was kept stable in a sinusoidal waveform regardless of the load fluctuations by forming voltage and current control using a deadbeat controller without increasing the current rating at the starting time. This paper describes this magnetic-stimulation device to which the start current was applied.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.5
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• pp.406-414
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• 2009

To cope with the high power density and low cost in switching power supply, LLC resonant converters with the two resonant tank circuits composed of resonance capacitors and two transformers are proposed in this paper. Each transformers used for the proposed resonant circuits are parallel connected in the primary and series connected in the secondary to reduce the current unbalance. The proposed LLC resonant converters are described and verified on 300W experimental prototype.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.7
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• pp.982-987
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• 2012

The power supply devices applied to the electric vehicle are required for high efficiency and high power density. This paper presents a bidirectional ZVS DC-DC converter. A bidirectional DC-DC converter using the planar transformer has advantages of high efficiency, simple circuit, and lightweight. The operating principle, theoretical analysis, and design guidelines are provided in this paper. The simulation waveforms of the proposed converter are shown to verify its feasibility.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.4
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• pp.617-621
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• 2016

In addition to the energy storage facilities based on high power technologies, Electric double layer capacitors(EDLC) are today's candidate for power quality stabilization. However, its low energy density is often inhibiting factor for application of electric power industry. Hybrid supercapacitor is an promising energy storage device that positioned between conventional EDLC and Li-ion battery. This paper describes the preparation and characteristics of a hybrid supercapacitor and module for power quality stabilization. A cylindrical 3200F hybrid supercapacitor ($60{\times}74.5mm$) was assembled by using the $Li_4Ti_5O_{12}$ electrode as an anode and activated carbon as a cathode. It shows 2.5 times higher energy density than conventional EDLC with the same volume. In order to determine the characteristics of the hybrid supercapacitor Module for uninterruptible power supply (UPS), hybrid supercapacitor cells were connected in series with active balancing circuit. At even the high current density of 14A(10C), Module prepared by 18 cells showed the capacitance of 170F at 30~50V, suggesting the applicability for UPS.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.7
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• pp.473-479
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• 2015

Hybrid supercapacitors with high power density and long cycle life are widely used for emergency power source of LED emergency luminaires. In this paper, we designed and fabricated a hybrid capacitor cell and a module for the LED emergency luminaires. Using hybrid supercapacitor cells (1,000 F, 2.8 V), we designed a module in a 10-year warranty considering aging and ESR. Considering the ESR and efficiency has been designed to module with 1,000 F 5.6 V design results in 2 series and 2 parallel combination. Module was used to confirm that the operation 77.5 minutes at room temperature, discharge LED emergency luminaires with 2 W. As a LED emergency luminaires of emergency power supply that we can support more than 10 years of life was confirmed the applicability of hybrid supercapacitor.

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.91-94
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• 2000

This paper introduces the design of low-power, fast-locking delay locked-loop using complementary pass transistor logic(CPL). Low-power design has become one of the most important in the modem VLSI application. CPL has the advantage of fast speed, high density, and low power with signal buffering between stages. Based on this analysis, we concluded that the I/O performance can be beyond 500㎒, 2-poly, 2-metal 0.65$\mu\textrm{m}$, 3.3V supply.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.3
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• pp.9-14
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• 2012

Robust power delivery and distribution are considered one of the major challenges in electronic devices today. As a technology develops (i.e. frequency and complexity, increase and size decreases), both power density and power supply noise increase, and voltage supply margin decreases. In addition, thermal problem is induced due to high power and poor power distribution. Until now most of studies to improve power delivery and distribution have been focused on device circuit or system architecture designs. Interconnect process technologies to resolve power delivery issues have not greatly been explored so far, but recently it becomes of great interest as power increases and voltage specification decreases in a smaller chip size.

• Journal of IKEEE
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• v.13 no.4
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• pp.9-14
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• 2009

This paper describes measurement of an on-ship power supply noise in mixed-signal integrated circuits. To measure the on-chip power supply noise, we can check the effects of analog circuits and compensate it. This circuit consists of two independent measurement channels, each consisting of a sample and hold circuit and a frequency to digital converter which has a buffer and voltage controlled oscillator(VCO). The time-based voltage information and frequency-based power spectrum density(PSD) can be achieved by a simple analog to digital conversion scheme. The buffer works like a unit-gain buffer with a wide bandwidth and VCO has a high gain to improve resolution. This circuit was fabricated in a 0.18um CMOS technology and has 2.06mV/count. The noise measurement circuit consumes 15mW and occupies $0.768mm^2$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.735-737
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• 2017

An Off grid or remote solar electric systems are an energy supply to our home or to our companies without the utility of Grid at all. Off grid solar systems are very important for those who live in remote locations especially for developing countries where getting the electric grid is extremely expensive, inconvenient or for those who doesn't need to pay a monthly bill with the electric bill in general. The main critical components of any solar power system or renewable energy harvesting systems are the energy storage systems and its charge controller system. Energy storage systems are the essential integral part of a solar energy harvesting system and in general for all renewable energy harvesting systems. To provide an optimal solution of both high power density and high energy density at the same time we have to use hybrid energy storage systems (HESS), that combine two or more energy storage technologies with complementary characteristics. In this present work, design and simulation we use two storage systems supercapacitor for high power density and lithium based battery for high energy density. Here the system incorporates fast-response supercapacitors to provide power to manage solar smoothing and uses a battery for load shifting. On this paper discuss that the total energy throughout of the battery is much reduced and the typical thermal stresses caused by high discharge rate responses are mitigated by integrating supercapacitors with the battery storage system. In addition of the above discussion the off grid solar electric energy harvesting presented in this research paper includes battery and supercapacitor management system, MPPT (maximum power point tracking) system and back/boost convertors. On this present work the entire model of off grid electric energy harvesting system and all other functional blocks of that system is implemented in MATLAB Simulink.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.365-366
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• 2017

LLC resonant DC-DC converter is widely used in many kinds of applications such as battery energy storage systems, wireless power transfer and high voltage power supply. It is because of characteristics like high efficiency, power density, isolation, wide power level and stability enhancement at high switching frequency. Small signal modeling helps to design controller of the converter by approximating the behavior of nonlinear system with linear state equations. This paper presents comparison between small signal modeling analysis and experimental results of LLC resonant converter.