• Journal of Korean Society for Atmospheric Environment
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• v.15 no.4
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• pp.475-483
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• 1999

A lab-scale test was carried out to study the reduction of electrical energy consumption in the pulsed corona discharge process for nitrogen oxides removal. The experiment was mainly focused on 1) the activation of pollution removal reactions by chemical additives and 2) the optimization of electrical circuit for the efficient energy transfer from the power supply to the corona reactor. Hydrocarbon chemical additives used in the experiment are thought to be responsible for the enhancement of the NO conversion through the chain reactions of free radicals such as, R, RCO, and RO. Electrical energy consumption per converted NO molecule has a minimum value of 17 eV when pentanol is injected. When ethylene and propylene are injected, 30 eV and 22 eV of electrical energy consumption is required for the conversion of NO molecule respectively. The ratio of the pulse forming capacitance$(C_e)$ to the reactor capacitance$(C_R)$ plays an important role in the energy transfer efficiency to the reactor. Maximum energy transfer efficiency of approximately 72% could be obtained by using the pulse forming capacitance which is 3.4 times larger than the reactor capacitance, and also the maximum NO conversion efficiency was observed with the same condition.

• Journal of the Korean institute of surface engineering
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• v.41 no.3
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• pp.94-101
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• 2008

A new convenient magnet array module is designed to investigate effects of magnetic field array on magnetron discharge characteristics. Magnetic field analysis showed good agreement of measured discharge region by a CCD device which has a high quantum efficiency over visible wavelength range. OES (optical emission spectroscopy) showed major emission peaks are from electronic transitions in 400 nm range and 800 nm range. Effects of driving voltage characteristics were analyzed in a point of electron drift trajectories and ionizing collision frequencies. Pulsed dc with a fast rising and falling time was analyzed to have potential to increase ionization collisions by putting a burst of hot electrons and to raise sheath potential. From measured voltage and current waveform, maximum of -1000 V peak was generated with $-400\;V_{rms}$ conditions. Possibility of a properly designed magnetron cathode was shown to be used as a melting device. Cu was successfully melted with power density of a several tens of $W/cm^2$.

• Bulletin of the Korean Chemical Society
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• v.15 no.8
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• pp.663-669
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• 1994

Decay kinetics of Ga(5s), Ga(5p) and Ga(4d) atoms in Ar were studied by laser induced fluorescence technique. Theground state gallium atoms in the gas phase were generated by pulsed dc discharge of trimethyl gallium and argon mixtures. Both pulsed discharge and YAG-DYE laser system were controlled by a dual channel pulse generator and the delay time between the end of discharge and laser pulses was set 3.0-6.0 ms. The Ga(5s) and Ga(4d) atoms were generated by single photon excitation from the ground state Ga atoms and radiative lifetimes as well as the total quenching rate constants in Ar were obtained from the pressure dependence of the fluorescence decay rates. The Ga(5p) atoms were populated by a two-photon excitation method and the cascade fluorescence from Ga(5s) atoms were analyzed to extract quenching rate constant of Ga(5p) atoms by Ar in addition to radiative lifetimes of Ga(5p) state. The magnitudes of the quenching rate constants by Ar for the low-lying excited states of Ga atoms are 1.6-3$ {\times}10^{-11}cm^3$ molecul$e^{-1}s^{-1}$, which are much larger than those for alkali, alkaline earth and Group 12 metals. Based on the measured rate constants, kinetic simulations were done to assign state-to-state rate constants.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.832-839
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• 2010

The pulse discharge anchor is a method to increase the capacity of anchors using electric discharge geotechnical technologies, which is also known as pulse discharge and electric-spark technologies. The pulse discharge anchor has bulbed bond length that is expanded by high voltage electrokinetic pulse energy. 24 anchors were installed in the weathered soil and sandy clay at the Geotechnical Experimentation Site at Sungkyunkwan University in Suwon, Korea and attached strain gauge at 10 anchors. The numerical predictions by Beam-Column analysis were compared with observed measurements in a field load test.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.12
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• pp.2685-2692
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• 2009

We propose pulsed magnetic stimulation below 30W by the AC(60Hz) switching control of leakage transformer primary which has some advantage of cost and size compared to a typical pulsed power supply. Pulse repetition rate is adjusted from 5Hz to 60Hz to control magnetic stimulation output. In this magnetic stimulation, a low voltage open loop control for high voltage discharge circuit is employed to avoid the HV sampling or switching and high voltage leakage transformer is used to convert rectified low voltage pulse to high voltage one. A ZCS(Zero Cross Switch)circuit and a DSP & FPGA are used to control gate signal of SCR precisely. The pulse repetition rate is limited by 60Hz due to the frequency of AC line and a high leakage inductance. The maximum magnetic stimulation output was obtained about 33W at pulse repetition rate of 60Hz, total 40, 80, 120, $160^{\circ}$, SCR gate trigger angle $90^{\circ}$ and total output.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.16-23
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• 2018

Alternative technologies for sludge treatment and disposal need to be developed urgently because the amount of produced production has increased continuously. In this study, Pulsed Electric Fields (PEF) technique was applied for sludge solubilization and the performance was evaluated. The PEF equipped with electrodes coated by epoxy resin and teflon was inducted to the activated sludge suspension, and the effect of the coating materials on the solubilization was determined. In addition, the effect of the applied voltage on the solubilization yield was investigated as the applied voltage was increased from 6 to 12 and 15 kV. Sludge solubilization was not observed when the epoxy-coated electrode was used for PEF induction regardless of the applied voltage. However, sludge solubilization occurred when 12 and 15 kV were applied to the teflon-coated electrodes. The MLSS decreased to 9%, and the soluble-COD increased to 496% when the applied voltage was 15 kV. But sludge solubilization did not happen under 6 kV condition. The corona discharge was observed at applied voltages of 12 and 15 kV, (Ed- sorry but I cannot understand the following highlight) but if 6 kV, strongly indicating that the corona discharge make the sludge solubilized, which suggests that the critical voltage for sludge solubilization lies between 6 and 12 kV. Consequently, proper selection of electrode-coating materials and the applied voltage of PEF could lead to sludge solubilization by corona discharge.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.1
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• pp.80-84
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• 2014

The discharge characteristics of Surface Dielectric Barrier Discharge (SDBD) reactor are investigated to find optimal driving condition with adjusting various parameter. When the high voltage with sine wave form is applied to SDBD source, successive pulsed current waveforms are observed owing to multiple ignitions through the long discharge channel and wall charge accumulation on the dielectric surface. The discharge voltage, total charge between dielectrics, mean energy and power are calculated from measured current and voltage according to electrode gap and dielectric thickness. Discharge mode transition from filamentary to diffusive glow is observed for narrow gap and high applied voltage case. However, when the diffusive discharge is occurred with high applied voltage, the actual firing voltage is always lower than that with low driving voltage. The $Si_3N_4$, $MgF_2$, $Al_2O_3$ and $TiO_2$ are considered for dielectric protection and high secondary electron emission coefficient. SDBD with $MgF_2$ shows the lowest breakdown voltage. $MgF_2$ thin film is proposed as a protection layer for low voltage atmospheric dielectric barrier discharge devices.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2421-2424
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• 2018

A direct measurement of an initiation carrier injection for a low voltage discharge is presented. A self-sustained pulsed discharge is utilized to characterize electrical responses of a glow discharge for varying amounts of injected initiation carriers. It is clearly demonstrated that the initiation carrier injection affects the ignition time and the breakdown voltage of the primary discharge. An abrupt reduction in the breakdown voltage for a $300{\mu}m$ gap pin-plate discharge is observed when a threshold carrier density of $3{\times}10^{11}cm^{-3}$ is injected and the breakdown voltage continues to decrease to 250 V with increasing the initiation carrier injection beyond the threshold density.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.5
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• pp.203-210
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• 2003

This paper describes high voltage and high energy density capacitor developed for pulsed power applications. The rated voltage of the developed capacitor is DC 22 [kV], the capacitance is 206 [$\mu$F] and the energy density is about 0.7 [kJ/kg]. Polypropylene film and kraft paper were used as the dielectrics. The ratio of the thickness of each dielectric material which consists of the composite dielectric structure, stacking factor and the termination method were determined by the charging and discharging tests on model capacitors. In terms of energy density, the developed capacitor has higher energy density compared with the products of foreign leading companies. In addition, it has been proved that the life expectancy can be more over 2000 shots through the charging and discharging test. The voltage reversal factor was 20%. This capacitor can be used as numerous discharge applications such as military, medical, industrial fields.

• Journal of Magnetics
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• v.1 no.2
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• pp.94-100
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• 1996

A hysteresis loop tracer using a pulsed high magnetic field of 113.4 kOe, which is suitable for rare earth based permanent magnets, is constructed. The high pulsed magnetic field is generated by discharging a large capacitance charge (5 mF) with a voltage of 600 V into an air solenoid with the inner diameter of 14 mm, outer diameter of 36 mm and the lingth of 34 mm. A computer simulation method is used for the construction of an electromagnet to optimize the many parameters such as the discharge current, generated pulsed magnetic field intensity, thermal dissipation, capacitance, charged voltage, period of damping oscillation and solenoid geometry. By using the hysteresis loop tracer constructed in this work, we are able to measure hystersis loops of several rare earth based permanent magnets with large values of the remanent magnetization, coercvity and energy product.