• Journal of Environmental Science International
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• v.17 no.7
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• pp.817-826
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• 2008

Using high voltage electric fields induced by high voltage AC (10-12 kV/cm, 20 kHz) and pulsed (20-30 kV/cm, 40 Hz) electric field generator as a semipermanent and environment-friendly disinfecting apparatus, the disinfection effect of coliform group in the effluent of sewage plant was investigated. The effects of electric field strength, treatment time, discharge area of a discharge tube, water quality factors (electric conductivity, pH and SS) on its death rate were examined. The death rate of coliform group was increased with increasing electric field strength and treatment time. For AC and pulsed electric field generator, the critical electric field strength was 6 kV/cm and 2 kV/cm, respectively, and the critical treatment time was 5 min and 2 min, respectively, regardless of electric field strength. Comparing the death rate of coliform group by AC and pulsed electric fields used in this study, its death rate was higher for the latter than the former, but did not increase linearly with increasing electric field strength. The results obtained for the effects of discharge area, electric conductivity, pH and SS on the death rate of coliform group using AC electric field (12 kV/cm, 20 kHz) were as follows: its death rate showed the trend to increase linearly with increasing discharge area; for the effect of electric conductivity, its death rate was increased with increasing electric conductivity, regardless of ionic species, increased with increasing cationic valency, but was similar between the same cationic valency; the pH $5{\sim}9$ used in this study did not affect its death rate; its death rate was decreased with increasing SS concentration.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2007-2009
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• 1999

In this paper, discharge domain of wire-cylindrical plasma reactor was separated from a gas flow duct to avoid unstable discharge by aerosol particle deposited on discharge electrode and grounded electrode. The NOx, SOx removal was experimentally investigated by a reaction induced to ammonium nitrate, ammonium sulfate using a low price of aqueous NaOH solution and a small quantity of ammonia. Volume percentage of aqueous NaOH solution used was 20% and $N_2$ flow rate was 2.5[$\ell$/min] for bubbling aqueous NaOH solution. Ammonia gas(14.82%) balanced by argon was diluted by air and was introduced to a main simulated flue gas duct through $NH_3$ injection system which was in downstream of reactor. The $NH_3$ molecular ratio[MR] was determined based on $NH_3$ to [NO+$SO_2$]. MR is 1.5. The NOx removal rates increased in the order of DC, AC and pulse, but SOx removal rates was not significantly effected by source of electricity. The NOx removal rate slightly decreased with increasing initial concentration but SOx removal rate was not significantly effect by initial concentration, and NOx, SOx removal rates decreased with increasing gas flow rate.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.704-709
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• 2011

Depolymerization of fucoidan induced by contact glow discharge electrolysis(CGDE) was investigated. To utilize fucoidan as a functional food material after CGDE, organic acids were used as a electrolyte in CGDE process. Experimental results showed that CGDE using organic acid reduced the molecular weight of fucoidan effectively. As electrolyte concentration increased, onset voltage of glow discharge decreased and onset current of glow discharge increased. From the variation of molecular weight of fucoidan with the reaction time, it was demonstrated that the degradation of fucoidan followed a first-order rate law. Molecular weight of fucoidan treated with CGDE using organic acid was about 77 times lower compared to initial fucoidan with little free sulfate.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1B
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• pp.105-109
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• 2009

It is a well known fact that baseflow discharge of rainfall runoff impacts on water quality of surface water significantly. In this paper, impacts of nitrate discharged as base flow on stream water quality were studied by using a software, PULSE from USGS to calculate monthly ground water discharge from hydrograph. We used water quality and flow rate data for Ghapcehon2 site in Daejeon city for year 2005 as well as ground water quality data in the watershed acquired from government agencies. Agricultural and forestry land use are dominant for upstream of Ghapcheon2 in the watershed. Base flow contributes about 85~95% of stream flows during spring and fall while 25~38% of stream flow was induced by base flow during summer and winter. Monthly nitrate loading discharged as base flow for Ghapcheon2 was estimated by using averaged nitrate concentration of groundwater in the watershed. Nitrate loading induced by base flow at Ghapcheon2 was estimated as 5.4 ton of $NO_{3}{^-}-N/km^{2}$, which is about 60% of nitrate loading of surface water, 9.2 ton of $NO_{3}{^-}-N/km^{2}$. Seasonal variation of nitrate concentration of base flow was estimated by dividing monthly nitrate loading by monthly base flow discharge. Nitrate concentration of groundwater was increasing from rainy season. From this study, it can be understood that ground water quality monitoring is important for the proper manage of surface water quality.

• Proceedings of the Korean Vacuum Society Conference
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• 2003.08a
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• pp.215-215
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• 2003

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.1
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• pp.36-40
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• 2004

A new laser Doppler velocimeter employing a $CO_2$ laser has been developed by using its photoacoustic effect. A change in the pressure of a discharge, induced by mixing of a returned wave with an originally existing wave inside the cavity, is employed to detect the Doppler frequency shift. We found that a Doppler frequency shift as much as 34 KHz was detected, and also a good linear relationship between the velocity and the Doppler frequency shift was obtained.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1378-1383
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• 2004

Rogowski coil is a kind of sensor for high amplitude and very short period current and suitable for the measurement of PD pulse. This paper have simulated the relations between PD signals and Rogowski coil which has its own equivalent circuit and investigated signals of Rogowski coil induced by PD pulse current. and compared with the PD signal obtained from conventional PD measuring system in accordance with IEC60270.

• Proceedings of the KIEE Conference
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• 1985.07a
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• pp.127-130
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• 1985

A stochastic model to predict radio interference field as caused by corona discharges on high voltage transmission lines has been developed. This model is based on corona discharge distributed randomly in time and space. A stochastic model for the corona current induced by corona discharges on power lines is proposed. On the basis of the proposed corona current model, a rigorous analysis is presented to evaluate the radio interference (RI) field caused by corona discharges on a single conductor using the stochastic method.

• Proceedings of the Korean Vacuum Society Conference
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• 2004.02a
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• pp.138-138
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• 2004

• Progress in Superconductivity and Cryogenics
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• v.2 no.1
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• pp.24-30
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• 2000

This paper present the characteristics of the internal induced voltage and arc phenomena in liquid helium at the energy transfer from a superconducting magnet to a load resistor. Especially generation mechanism of the oscillated wave from of the coil terminal voltage is analyzed by considering circuit constant of the superconducting magnet, load condition and arc resistance of the mechanical opening switch. The wavefront and peak portion of the voltage are strongly influenced by arc discharge triggered by the switch separation in liquid helium. Abrupt arc extinction leads to voltage oscillation with an enormous peak. It is suggested that the superconducting magnet should be designed to ensure the internal surge when arc is possibly formed by switch opening or coil short circuit between turns or layers. Finally, a suppression method of the oscillating surge is proposed based on the load condition.