• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.291-293
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• 2003

A semiconductor switch-based fast hi-polar high voltage pulse generator is proposed in this paper The proposed pulse system is made of a thyristor based-rectifier, DC link capacitor, a push-pull resonant inverter, a high voltage transformer. secondary capacitor, a high voltage IGBT & diode stacks, and a variable capacitor. The proposed system makes hi-polar high voltage sinusoidal waveform using resonance between leakage inductance of the transformer and secondary capacitor and transfers energy to output load at maximum of the secondary capacitor voltage. Compared to previous hi-polar high voltage pulse power supply using nonlinear transmission line, the proposed pulse power system using only semiconductor switches has simple structure and gives high efficiency

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.2011-2016
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• 2018

In this study, we have been investigated pin to plate pulsed bi-polar discharges in saline solutions, where bubble generation occurs. We integrate basic I-V-t electrical characteristics with the ICCD shadowgraph images, and finally instant and time averaged I-V waveforms. We observed that the bubble formation phase dynamics is quite different corresponding to the polarity applied to the pin electrode. When the pin electrode is a cathode, the bubble tends to be periodically detached from the pin electrode and the numerous tiny voltage spikes occur related to the electron emission from a pin cathode casing via, we judge from, direct dissociation of water molecules by energetic electrons. On the contrary, the bubble tends to stick to the pin electrode, when the pin electrode is anode; the bubble grows in size throughout the pulse duration. The dynamic electrical characteristics relative to the applied polarity of a pin electrode are presented and discussed by analysis of time averaged I-V waveforms.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.4
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• pp.371-374
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• 2012

DC/DC switching power converters produce DC output voltages from different stable DC input sources regulated by a bi-polar transistor. The converters can be used in regenerative braking of DC motors to return energy back in the supply, resulting in energy savings for the systems containing frequent stops. The voltage mode DC/DC converter is composed of a PWM (Pulse Width Modulation) controller, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), an inductor, and capacitors, etc. PWM is applied to control and regulate the total output voltage. It is shown that the output of DC/DC converter depends on the variation of threshold voltage at MOSFET and the variation of pulse width. In the PWM operation, the missing pulses, the changes in pulse width, and a change in the period of the output waveform are studied by SPICE (Simulation Program with Integrated Circuit Emphasis) and experiments.

• Journal of Korean Vacuum Science & Technology
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• v.7 no.2
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• pp.45-56
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• 2003

A high flux metal plasma pulse ion source, which can simultaneously perform ion implantation and deposition, was developed and tested to evaluate its performance using the prototype. Flux of ion source was measured to be 5 A and bi-polar pulse power supply with a peak voltage of 250 V, repetition of 20 Hz and width of 100 ${\mu}\textrm{s}$ has an output current of 2 kA and average power of 2 kW. Trigger power supply is a high voltage pulse generator producing a peak voltage of 12 kV, peak current of 50 A and repetition rate of 20 Hz. The acceleration column for providing target energy up to ion implantation is carefully designed and compatible with UHV (ultra high vacuum) application. Prototype systems including various ion sources are fabricated for the performance test in the vacuum and evaluated to be more competitive than the existing equipments through repeated deposition experiments.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.1
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• pp.31-37
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• 2009

Hybrid ballast for field emission lamp with CNT (carbon nano tube) emitter is proposed. Hybrid ballast consists of a high voltage dc part and hi-polar pulse generation part. Field emission lamp with CNT lamp is composed of three electrodes (anode, gate, and cathode). High voltage dc part is for anode and gate and hi-polar pulse generation part is for gate and cathode in CNT triode respectively. The experimental results demonstrate that the proposed topology is good for driving CNT lamp. To protect the lamp and ballast, OCP (Over Current Protection), OVP (Over Voltage Protection), and OTP (Over Temperature Protection) are added and the experimental results demonstrate that the proposed method is good for driving field emission lamp with CNT emitter.

• Journal of Biomedical Engineering Research
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• v.27 no.1
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• pp.30-37
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• 2006

Injecting currents into an electrically conducting subject, we may measure the induced magnetic flux density distributions using an MRI scanner. The measured data are utilized to reconstruct cross-sectional images of internal conductivity and current density distributions in Magnetic Resonance Electrical Impedance Tomography (MREIT). Injection currents are usually provided in a form of mono-polar or bi-polar pulses synchronized with an MR pulse sequence. Given an MRI scanner performing the MR phase imaging to extract the induced magnetic flux density data, the current source becomes one of the key parts determining the signal-to-noise ratio (SNR) of the measured data. Since this SNR is crucial in determining the quality of reconstructed MREIT images, special care must be given in the design and implementation of the current source. This paper describes a current source design for MREIT with features including interleaved current injection, arbitrary current waveform, electrode switching to discharge any stored charge from previous current injections, optical isolation from an MR spectrometer and PC, precise current injection timing control synchronized with any MR pulse sequence, and versatile PC control program. The performance of the current source was verified using a 3T MRI scanner and saline phantoms.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.166-168
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• 2005

본 논문에서는 고효율 고휘도의 신광원을 개발함에 있어, 전계방출(Field Emission) 원리를 이용하여, 이미터로서의 성능이 입증된 CNT(Carbon Nanotube, 탄소나노튜브)를 이용한 평판 형태의 신개념 램프에 대한 펄스전원장치에 대한 연구를 하였다. 특히, Triode형 CNT 램프 구동을 위해서는 캐소드(cathode)와 게이트(gate) 사이에서 양방향(Bi-polar) 저전압 펄스가 필요하고 애노드(anode)에 직류 고전압이 필요하여 이를 위한 저전압 펄스 및 직류 고전압 전원장치에 대한 개발을 연구하였다.