• 조명전기설비학회논문지
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• 제20권8호
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• pp.6-14
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• 2006

본 논문은 TFT-LCD(Thin Film Transistor Liquid Crystal Display) PECVD(Plasma Enhanced Chemical Vapor Deposition) 장비 공정용 챔버(Chamber) 세정을 위한 새로운 플라즈마 세정방법에 적합한 플라즈마 발생방법과 플라즈마 발생을 위한 고주파 전원장치의 전력회로에 관한 연구이다. 세정에 요구되는 고밀도 플라즈마는 안테나 형태의 기존 ICP(Inductively Coupled Plasma) 방식에 강자성체인 페라이트 코어를 적용하므로 써 $1{\times}10^{11}[EA/cm^3]$이상의 고밀도 플라즈마 발생을 가능하게 하였다. 플라즈마 발생을 위한 400[kHz] 고주파 전력 변환장치의 경우 범용 HB(Half Bridge) 인버터 방식을 적용하여 플라즈마 부하에서도 안정적인 영전압 스위칭 동작을 확인 하였다. 변압기 직렬결합 방식을 사용한 10[kW] 고출력을 통해 $A_r$과 $NF_3$가스 분위기하에서 플라즈마의 밀도와 $NF_3$가스 분해율을 측정하므로서 고주파 전력 변환 장치의 성능을 입증하였다.

• Journal of Magnetics
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• 제19권1호
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• pp.20-27
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• 2014

This study examined the relationships between protein expression and Poly ADP ribose polymerase in brain cell death in brains damaged by thrombotic stroke and treated with the Full Wave- Cockroft Walton (FWCW) method of Transcranial Magnetic Stimulation (TMS). The two-way switching element for TMS drove a half-bridge inverter of the current resonance of direct current voltage (+) and direct current voltage (-), and the experiment was conducted by stimulating the mice with thrombotic stroke through a range of pulses. Thrombotic stroke was caused of ligation of the common carotid artery of male SD mice, and blood reperfusion was conducted five minutes later. Protein expression was examined in immune reaction cells, which reacted to an antibody to Poly ADP ribose polymerase in the cerebrum cells, and western blotting. Observations of the PARP changes after thrombotic stroke showed that the number of Poly ADP ribose polymerase reactions were significantly lower (p < 0.05) in the group treated with TMS of the FWCW than the group with thrombotic stroke 24 hours after its onset. The application of FWCW-TMS helped prevent the necrosis of nerve cells and might prevent the brain damage that occurs as a result of thrombotic stroke, and improve the function recovery and disorder of brain cells.

• 전력전자학회논문지
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• 제21권4호
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• pp.351-355
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• 2016

Welding machines are high-capacity systems used in a low-frequency range using IGBT. As their system is similar to a large transformer, most welding machines suffer a great loss because of hard switching and vast leakage inductance. A voltage-balancing circuit is designed to overcome these shortcomings. This circuit can reduce the transformer size by making it into a high frequency and reducing the input voltage by half and by adopting a serial structure that connects two full-bridges in a series to use a MOSFET with a good property at high frequency. In addition, a Schottky diode is used in the primary rectifier to overcome the low efficiency of most welding machines. To use the Schottky diode with a reliably relatively low withstanding voltage, an active snubber is adopted to effectively limit the ringing voltage of the diode cut-off voltage.

• 조명전기설비학회논문지
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• 제16권1호
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• pp.20-26
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• 2002

고압방전램프에는 고압수은램프, 고압나트륨램프와 메탈핼라이프램프가 있다. 메탈핼라이드램프는 가장 효율 좋을 램프들 중 하나이며 고효율, 고연색성과 집광능력이 좋다. 이 연구의 목적은 AC 100∼277의 프리볼트입력용 전자식안정기를 개발하여 메탈핼라이드(MH70W)를 점등시키는 것이다. 개발된 전자식안정기는 프리볼트입력용컨버터, 플라이백컨버터와 하프브리지인버터, 이그나이터와 보호기 그리고 제어기로 구성되어 있다. 실험 결과 개발된 전자식안정기는 프리볼트입력(AC 100∼277V)에 따라 메탈핼라이드램프(MH70W)가 매우 잘 점등되었다.

• Journal of Power Electronics
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• 제16권4호
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• pp.1469-1482
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• 2016

In hybrid energy storage systems, supercapacitors are usually connected in series to meet the required voltage levels. Equalizers are effective in prolonging the life of hybrid energy storage systems because they eliminate the voltage imbalance on cells. This study proposes a modularized equalizer, which is based on a combination of a half-bridge inverter, an inductor, and two auxiliary capacitors. The proposed equalizer inherits the advantages of inductor-based equalization systems, but it also offers unique merits, such as low switching losses and an easy-to-use control algorithm. The zero-voltage switching scheme is analyzed, and the power model is established. A fixed-frequency operation strategy is proposed to simplify the control and lower the cost. The switching patterns and conditions for zero-voltage switching are discussed. Simulation results based on PSIM are presented to verify the validity of the proposed equalizer. An equalization test for two supercapacitor cells is performed. An experimental hybrid energy storage system, which consists of batteries and supercapacitors, is established to verify the performance of the proposed equalizer. The analysis, simulation results, and experimental results are in good agreement, thus indicating that the circuit is practical.

• 전기학회논문지
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• 제59권8호
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• pp.1394-1400
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• 2010

This paper introduces a newly improved Ultra-FRFET that has much better reverse recovery characteristic than that of the typical MOSFET and presents its effectiveness in the HV-BLU system of LCD TVs. The reverse recovery time, $T_{rr}$ of Ultra-FRFET is shorter than 40nsec and the peak value of reverse current, $i_{rr}$ is also much smaller compared to the typical MOSFET's, which are sufficient to prevent the MOSFET’s failures without additional FRDs and diodes in HV-BLU system with a half-bridge resonant inverter topology worked by PWM method. In order to verify the validity, the loss analysis and the implementation results in cases when both the conventional solution using typical MOSFETs with additional FRDs and a new solution using Ultra-FRFETs are applied to a HV-BLU of 40" LCD TV are presented. As a result, the effectiveness of Ultra-FRFET was verified and the results are presented in this paper.

• 조명전기설비학회논문지
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• 제26권8호
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• pp.79-87
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• 2012

Currently, The method to produce a brewing body for dentistry supplementation water produces a brewing body by fabrication, burying and it is heat wish in city gas and oxygen. It uses an original judgment found airplane the brewing body uses a spring of the back wait that melting temperature dissolved various alloys in by a blow pipe, and to generate centrifugal force and produces it. In addition, because it uses preheating to dissolve an alloy in general, it is hard to regulate the appropriate melting temperature of the alloy and brewing time and generates a brewing defect hereby same as gas industry and pinhole and shows the defect of the supplementation thing due to the super-heating. In this paper, We developed the high induction heating system which it could set brewing time,temperature and had durability and security,by the kind of the alloy to produce a high quality prosthetic thing brewing body.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1703-1705
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• 2001

The pulsed Nd:YAG laser is used widely for materials processing and medical instrument etc. It is important to control the laser energy in those fields using a pulsed Nd:YAG laser. In this paper, constant-frequency current resonant half-bridge inverter and Cockcroft-Walton circuit are used to charge the energy storage capacitor variably. This laser power supply is designed and fabricated which has no high-voltage transformer, less switching losses, compact size and capability in varying the laser output power. Also, the output characteristics of this Nd:YAG laser system are investigated. The tested results are described.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.228-232
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• 2002

In this paper, In order to solve the problem is proposed using a new type of electronic ballast that the traditional magnetic ballasts operated at 50-60Hz have been suffered from noticeable flicker, high loss, large crest factor and heavy weight which is composed of rectifier, active power corrector, series resonant half bridge inverter, micro-controller and piezoelectric transformer for driving for driving T5 fluorescent lamp were manufactured. The proposed electronic ballast operated at high frequency (about 75kHz) shows a input power factor of more than 0.995, total harmonic distortion of less than $12\%$ and lamp current crest factor of less than 1.5, respectively. Output power and efficiency showed 28w and $85\%$, respectively. Accordingly, it is considered that the ballast using piezoelectric transformer can replace the typical electronic ballast.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1816-1819
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• 2002

Nowadays, CO2 lasers are used widely in many applications such as materials fabrication, communications, remote sensing and military purpose etc. It is important to control the laser output power in those fields. In this paper, current resonant half-bridge inverter and Cockcraft-Walton circuit are used to vary the laser output power. This laser power supply is designed and fabricated which has less switching losses and compact size. Also we used an IGBT(Insulated Gate Bipolar Transistor) as a switching device of a power supply and PIC one-chip microprocessor are used to control the gate signal of the IGBT precisely. We investigated the output characteristics of this CO2 laser. As a result, the maximum laser output power of 26[W] is obtained at the resonant frequency of about 13[kHz].