• Journal of the Korean Society of Safety
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• v.13 no.4
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• pp.162-171
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• 1998

This paper presents the harmonics obstacle analysis and countermeasure of electrical consumption a place. Harmonics that can be cosidered as a environmental pollution of the power systems become the cause of the accidents and damages. The responsibility of eliminating the harmonics firstly lies on the generating side. But the original characteristics of the system sush as the harmonic transfer characteristics and the impedance of the system affect each other in the process of the generation and transmission of the harmonic. Therefore it is very difficult to specify clearly the harmonic controlling responsibility, because electric machinery generating harmonics are various in the industrial fields. The output of a inverter has a high harmonic content. There are several ways of minimizing the output harmonic content. One way is to use pulse width modulation techniques within inverter. An alternative method is to combine a number of square-wave inverters. In this research, we measure the harmonic of the countermeasure of electrical consumption a place. The paper present the problem of new harmonic elimination method of PWM inverter fed induction motor system using W-FT series. In the future, the proposed PWM pattern by W-FT series is effective not only to the induction motor but also to the electromagnetic machine such as voltage reglator, UPS.

• The Korean Journal of Physiology and Pharmacology
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• v.4 no.4
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• pp.333-338
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• 2000

We have examined whether bile acids can affect the electrical and mechanical activities of circular smooth muscle of canine colon and ileum, using isometric tension measurement or patch clamp technique. It was found that a dilution of canine bile $(0.03{\sim}2%\;by\;volume)$ enhanced or inhibited the amplitude of spontaneous contractions. An individual component of bile, deoxycholic acid (DCA) enhanced the frequency and amplitude of the spontaneous contractile activity at $10^{-6}\;M,$ while DCA at $10^{-4}\;M$ inhibited the contraction. Similarly, the response to cholic acid was excitatory at $10^{-5}\;M$ and inhibitory at $3{\times}10^{-4}\;M.$ Taurocholic acid at $10^{-4}\;M$ enhanced the amplitude of muscle contraction. Electrically, canine bile at 1% reversibly depolarized the colonic myocytes under current clamp mode. Bile acids also elicited non-selective cation currents under voltage clamp studies, where $K^+$ currents were blocked and the $Cl^-$ gradient was adjusted so that $E_{Cl}^-$ was equal to -70 mV, a holding potential. The non-selective cation current might explain the depolarization caused by bile acids in intact muscles. Furthermore, the bile acid regulation of electrical and mechanical activities of intestinal smooth muscle may explain some of the pathophysiological conditions accompanying defects in bile reabsorption.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.559-561
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• 2008

본 논문에서는 실용적이며 신뢰성 있는 고전압 대용량 유도전동기 구동용 H-브릿지 멀티레벨 인버터를 개발하여 산업 현장에 적용한 내용을 소개하였다. 실용적인 PWM (Pulse Width Modulation)과 PEBB (Power Electronics Building Blocks)에 기초한 신뢰성 있는 분산 제어를 적용하였으며, H-브릿지 멀티레벨 인버터를 이용한 유도 전동기 벡터 제어시의 위상지연을 보상하여 제어 성능을 향상시켰다. 또한, Power Cell 고장 발생시 시스템을 정지하지 않으면서 효율적 운전을 가능하게 하는 3상 불평형 제어를 이용하여 잉여성을 확보하였다. 다양한 전압과 용량의 H-브릿지 멀티레벨 인버터를 설계 및 제작하여 각종 부하 실험, 산업 현장 적용을 통해 적용된 방법의 타당성과 실용성을 입증하였다. 또한 실제 제품 설계, 생산, 판매, 유지 보수 과정을 통해 설계의 유연성, 생산의 효율성, 유지 보수의 편리함, 그리고 사용자 요구에 대한 대응성이 우수함을 확인하였다.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1508-1516
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• 2015

A single phase H-bridge inverter is employed in conventional Inductive Power Transfer (IPT) systems as the primary side power supply. These systems may not be suitable for some high power applications, due to the constraints of the power electronic devices and the cost. A high-frequency cascaded multi-level inverter employed in IPT systems, which is suitable for high power applications, is presented in this paper. The Phase Shift Pulse Width Modulation (PS-PWM) method is proposed to realize power regulation and selective harmonic elimination. Explicit solutions against phase shift angle and pulse width are given according to the constraints of the selective harmonic elimination equation and the required voltage to avoid solving non-linear transcendental equations. The validity of the proposed control approach is verified by the experimental results obtained with a 2kW prototype system. This approach is expected to be useful for high power IPT applications, and the output power of each H-bridge unit is identical by the proposed approach.

• Journal of Power Electronics
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• v.18 no.2
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• pp.456-466
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• 2018

This paper introduces the development of a de-icer based on a full-bridge modular multilevel converter (FMMC). The FMMC can generate a wide range of DC voltages owing to its modularity, scalability, and redundancy, which makes it suitable for ice-melting applications. First, operating principles and voltage ranges are analyzed when FMMC is applied as a mobile de-icer. Second, two new startup strategies, constant modulation index and constant power startup strategies, are proposed. Third, the main control strategies of the de-icer are proposed. Fourth, a novel rated-current zero-power test scheme is proposed to simplify test conditions. Finally, a 10 kV 1.5 kA mobile MMC de-icer is designed and built, and experiments are carried out to validate the proposed startup, control strategies, and rated-current zero-power test scheme.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.1
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• pp.63-67
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• 2009

Current mismatch in a charge pump causes degradation in spectral purity of the phase locked loops(PLLs), such as reference spurs. The current mismatch can be reduced by increasing the output resistance of the charge pump, as in a cascoded output stage. However as the supply voltage is lowered, it is hard to stack transistors. In this paper, a new method for reducing the current mismatch is proposed. The proposed method is based on a feed-forward compensation for the channel length modulation effect of the output stage. The new method has been demonstrated through simulations on typical $0.18{\mu}m$ CMOS circuits.

• IEIE Transactions on Smart Processing and Computing
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• v.5 no.6
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• pp.454-461
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• 2016

A maximum power point tracking (MPPT) system with fast-tracked time and high power efficiency is presented in this paper. The proposed MPPT system uses an unbounded binary search (UBS) algorithm that continuously tracks the maximum power point (MPP) with a binary system to follow the MPP under rapid-weather-change conditions. The proposed algorithm can decide the correct direction of the MPPT system while comparing the previous power point with the present power point. And then, by fixing the MPP until finding the next MPP, there is no oscillation of voltage MPP, which maximizes the overall power efficiency of the photovoltaic module. With these advantages, this proposed UBS is able to detect the MPP more effectively. This MPPT system is based on a boost converter with a micro-control unit to control analog-to-digital converters and pulse width modulation. Analysis of this work and experimental results show that the proposed UBS MPPT provides fast, accurate tracking with no oscillation in situations where weather rapidly changes and shadow is caused by all sorts of things. The tracking time is reduced by 87.3% and 66.1% under dynamic-state and steady-state operation, respectively, as compared with the conventional 7-bit perturb and observe technique.

• Journal of Power Electronics
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• v.13 no.5
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• pp.737-745
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• 2013

Offshore wind farms are rapidly growing owing to their comparatively more stable wind conditions than onshore and land-based wind farms. The power capacity of offshore wind turbines has been increased to 5MW in order to capture a larger amount of wind energy, which results in an increase of each component's size. Furthermore, the weight of the marine turbine components installed in the nacelle directly influences the total mechanical design, as well as the operation and maintenance (O&M) costs. A reduction in the weight of the nacelle allows for cost-effective tower and foundation structures. On the other hand, longer transmission distances from an offshore wind turbine to the load leads to higher energy losses. In this regard, DC transmission is more useful than AC transmission in terms of efficiency because no reactive power is generated/consumed by DC transmission cables. This paper describes some of the challenges and difficulties faced in designing high-power-density power conversion systems (HPDPCSs) for offshore wind turbines. A new approach for high gain/high voltage systems is introduced using transformerless power conversion technologies. Finally, the proposed converter is evaluated in terms of step-up conversion ratio, device number, modulation, and costs.

• Journal of Power Electronics
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• v.17 no.1
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• pp.106-114
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• 2017

In this paper, the Selective Harmonic Mitigation-PWM (SHM-PWM) method is used in single-phase and three-phase Cascaded H-Bridge (CHB) inverters in order to fulfill different power quality standards such as EN 50160, CIGRE WG 36-05, IEC 61000-3-6 and IEC 61000-2-12. Non-equal DC link voltages are used to increase the degrees of freedom for the proposed SHM-PWM technique. In addition, it will be shown that the obtained solutions become continuous and without sudden changes. As a result, the look-up tables can be significantly reduced. The proposed three-phase modulation method can mitigate up to the 50th harmonic from the output voltage, while each switch has just one switching in a fundamental period. In other words, the switching frequency of the power switches are limited to 50 Hz, which is the lowest switching frequency that can be achieved in the multilevel converters, when the optimal selective harmonic mitigation method is employed. In single-phase mode, the proposed method can successfully mitigate harmonics up to the 50th, where the switching frequency is 150 Hz. Finally, the validity of the proposed method is verified by simulations and experiments on a 9-level CHB inverter.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.733-738
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• 2006

As the film transistor-liquid crystal display (TFTLCD) panels become larger and provide higher resolution, the propagation delay of row and column lines, the voltage modulation of Vcom, and the response time of liquid crystal affect the display images now more than in the past. It is more important to understand the electrical characteristic of TFT-LCD panels these days. This paper describes the electrical model of a 15-inch XGA ($1024{\times}768$) TFT-LCD panel. The parasitic resistance and capacitance of its panel are obtained by 3D simulation of a sub pixel. The accuracy of these data is verified by the measured values in an actual panel [1]. The developed panel simulation platform, the equivalent circuit of a 15-inch XGA panel, is simulated by HSPICE. The results of simulation are compared with those of experiment, according to changing the width of signal. Especially, the proposed simulation platform for modeling TFTLCD panels can be applied to large size LCD TVs. It can help panel and circuit designers to verify their ideas without making actual panels and circuits.