• 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 2013년도 추계학술대회 논문집
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• pp.229-230
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• 2013

The conventional Three-Stage electronic ballast is stable, but Two-Stage electronic ballast has been researching because of efficiency. Three-Stage electronic ballast is consisted of PFC circuit, buck converter, and inverter circuit, but Two-stage is consisted of PFC circuit, Buck-Inverter full bridge circuit. The Buck-Inverter full bridge inverter consists of two half bridge inverters for low frequency switching, and high frequency switching. In the case of street lamp it is far from a lamp to a ballast, the conventional pulsed high voltage ignitor can not turn on the HID lamps because of reduction of ignition voltage. Therefore, it needs to do the research on a resonant ignition to turn on the HID lamps. Therefore, in the Two-Stage electronic ballast which has the resonant tank for ignition, the transient resonant current because of low frequency changing is analyzed, the novel algorithm is proposed to resuce the transient current.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1600-1602
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• 2001

A pulsed power supply of 2.4MJ capacitor bank has been developed to make investigation into electric gun technology. It is made up of eight paralleled 300kJ modules, and can supply various shape of high current pulse by changing charging voltage, inductance, capacitance, and firing time of each module. The 300kJ module has been designed and fabricated for the maximum operating voltage of 22kV, peak current of 150kA, and pulse duration of 1msec. The experiments of the modules were done, and the equivalent circuit of the module was determined. The characteristics of the module were analyzed more deeply through the circuit simulation. The experiments of the paralleled modules with inductance of 20 $\mu$H and load resistance of 100 m$\Omega$ were performed, where the modules were discharged simultaneously and/or sequentially. The results of the experiments were analyzed. The 2.4MJ capacitor bank is currently used as the pulsed power supply for the ETCG (Electro Thermal Chemical Gun) research.

• 전력전자학회논문지
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• 제27권1호
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• pp.40-47
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• 2022

At present, the low-voltage, high-current type power supply is mainly used for effective sterilization in the ballast water treatment system. Research on PSFB converters without output capacitors has been ongoing. Such converters effectively treat ballast water without a separate disinfectant through electric pulses by applying a pulse-type power to the output electrode without an output capacitor. However, in the case of the pulse-type electrolysis treatment method, voltage overshoot can occur due to abrupt voltage fluctuations when the load changes, resulting in circuit reliability problems because of the output capacitorless system. Therefore, a new voltage control algorithm is required. In this paper, we will discuss voltage control for pulsed electrolysis topology without an output capacitor. The proposed voltage control method has been verified using Simulation and experiment. The usefulness of the proposed control method has been proven by the experimental results.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.294-299
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• 2004

An assessment of a novel laser-electric hybrid propulsion system was conducted, in which a laser-induced plasma was induced through laser beam irradiation onto a solid target and accelerated by electrical means instead of direct acceleration only by using a laser beam. A fundamental study of newly developed rectangular laser-assisted pulsed-plasma thruster (PPT) was conducted. On discharge characteristics and thrust performances with increased peak current compared to our previous study to increase effects of electromagnetic forces on plasma acceleration. Maximum peak current increased for our early study by increasing electromagnetic effects in a laser assisted PPT. At 8.65 J discharge energy, the maximum current reached about 8000 A. Plasma behaviors emitted from a thruster in various cases were observed with an ICCD camera. It was shown that the plasma behaviors were almost identical between low and high voltage cases in initial several hundred nanoseconds, however, plasma emission with longer duration was observed in higher voltage cases. Canted current sheet structures were also observed in the higher voltage cases using a larger capacitor. With a newly developed torsion-balance type thrust stand, thrust performances of laser assisted PPT could be estimated. The impulse bit and specific impulse linearly increased. On the other hand, coupling coefficient and the thrust efficiency did not increase linearly. The coupling coefficient decreased with energy showing maximum value (20.8 ？Nsec/J) at 0 J, or in a pure laser ablation cases. Thrust efficiency first decreased with energy from 0 to 1.4 J and then increased linearly with energy from 1.4 J to 8.6 J. At 8.65 J operation, impulse bit of 38.1 ？Nsec, specific impulse of 3791 sec, thrust efficiency of 8 %, and coupling coefficient of 4.3 ？Nsec/J were obtained.

• 전력전자학회논문지
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• 제24권6호
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• pp.411-418
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• 2019

Light-triggered thyristors (LTTs) are essential components in high-power applications, such as HVDC transmission and several pulsed-power applications. Generally, LTT fabrication includes a deep diffusion of aluminum as a p-type dopant to form a uniform p-base region, which needs careful concern for contamination and additional facilities in silicon semiconductor manufacturing factories. We fabricated 4-inch 5,000 V LTTs with boron implantation and diffusion process as a p-type dopant. The LTT contains a main cathode region, edge termination designed with a variation of lateral doping, breakover diode, integrated resistor, photosensitive area, and dV/dt protection region. The doping concentration of each region was adjusted with different doses of boron ion implantation. The fabricated LTTs showed good light triggering characteristics for a light pulse of 905 nm and a blocking voltage (V_DRM) of 6,500 V. They drove an average on-state current (I_TAVM) of 2,270 A, peak nonrepetitive surge current (I_TSM) of 61 kA, critical rate of rise of on-state current (di/dt) of 1,010 A/㎲, and limiting load integral (I²T) of 17 MA²s without damage to the device.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.266-268
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• 1997

High Voltage High Current Pulsed Electric Fields (HVHC-PEF) is a promising technology for the non-thermal pasteurization of foods and a sound complement or replacement to traditional thermal pasteurization, which inactivates bacteria and other microorganisms harmful to humans, but also degrades color, flavor, texture and nutrients. Foods can be pasteurized with pulsed electric fields at ambient or refrigerated temperatures for a short treatment time of seconds or less and the fresh-like quality of food is preserved. Although successful is laboratory tests, applying HVHC-PEF to food pasteurization on a large scale presents many unresolved engineering problems. In this paper the design considerations for 25kV 1kA class HVHC-PEF pasteurization equipment are anlyzed and experimental results are discussed.

• Journal of Advanced Marine Engineering and Technology
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• 제30권8호
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• pp.927-933
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• 2006

The structural and electrical characteristics of PLZT thin films fabricated onto $Pt/IrO_2/Ir/Ti/SiO_2/Si$ substrates by a pulsed laser deposition were investigated to develop the high dielectric thin films for capacitor layer of semiconductor memory devices The slim region 14/50/50 PLZT thin films were fabricated by PLD and estimated the characteristics for memory application 14/50/50 PLZT thin films have crystallize into perovskite structure at the $600^{\circ}C$ deposition temperature, 200 mTorr of oxygen pressure, and 2 $J/cm^2$ of laser energy density. In this condition PLZT thin films had the dielectric constant as high as 985, storage charge density 8.17 ${\mu}C/cm^2$ and charging time 0.20 ns. Leakage current density was less than $10^{-10}A/cm^2$ up to 5 V bias voltage.

• JSTS:Journal of Semiconductor Technology and Science
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• 제5권2호
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• pp.107-112
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• 2005

We present an AlGaN/GaN metal-insulator-semiconductor-heterostructure field effect transistor (MIS-HFET) with an $Al_2O_3-HfO_2$ laminated high-k dielectric, deposited by plasma enhanced atomic layer deposition (PEALD). Based on capacitance-voltage measurements, the dielectric constant of the deposited $Al_2O_3-HfO_2$ laminated layer was estimated to be as high as 15. The fabricated MIS-HFET with a gate length of 102 m exhibited a maximum drain current of 500 mA/mm and maximum tr-ansconductance of 125 mS/mm. The gate leakage current was at least 4 orders of magnitude lower than that of the reference HFET. The pulsed current-voltage curve revealed that the $Al_2O_3-HfO_2$ laminated dielectric effectively passivated the surface of the device.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권2호
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• pp.109-116
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• 1999

ZnO Varistor is an electronic ceramic device to absorb the surge voltage from low voltage to high. To investigate the puncture mechanism occurring in NnO varistor, the Voronoi simulation for formulating the relation between the applied voltage and the increase of the temperature inside grain is applied. The Voronoi network can realize the structure of the practical varistor better than the established simple network. Using the current through each grain and the voltage applied to the grain, Joule heating energy is calculated and the phenomenon that the puncture occurs can be analyzed quantitatively by simulating the electric and thermal characteristics according to the externally applied pulsed voltage.