• KCID journal
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• v.17 no.2
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• pp.71-81
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• 2010

Stream Pilot Project, which began in May 2003 and finished in December 2003, was selected to develop effective methods applicable to nature-like streams. Stream restoration projects aim to maintain or increase ecosystem goods and services while protecting downstream and coastal ecosystems. Fields environmental monitoring such as flow discharge and precipitation were conducted along the Idong stream for amount of channel zone change in 2007. This study selected three monitoring positions to measure the water level and discharge of flowing water. A stage-discharge relation is obtained from direct discharge measurements for three stations by fitting an empirical relationship to the data set. Since discharge measures are made only for low flow conditions, a curve of discharge against stage can then be built by fitting these data with a power curve. And this study used data obtained from floodmark checkup as well as HEC-RAS model to analyze the hydrodynamic characteristics of monitoring sites. Reach-averaged hydraulic parameters for the supply reach were calculated from the small area's HEC-RAS model for Idong stream, and a HEC-RAS model used to analyze hydraulics for a period in 2007, after the stream was considered bank stabilization.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.5
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• pp.482-489
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• 2002

This paper studies the stand-alone photovoltaic system for the solar lighting lamp. The solar lighting lamp has PV modules, batteries, and charge & discharge system. The charge efficiency is improved for the control of each battery which is divided the charge from the discharge to change the structure of existing solar lighting lamp charge & discharge system. so, the charge and discharge times are reduced of 50% and the depth of discharge control can be controlled in the discharge cut off voltage. It can be effective of the battery use. If a battery is out of order, this system can be executed for a regular period. So we saved the repair cost and developed of system's stabilization. It Is possible to make economical effects to apply for solar lighting lamp used photovoltaic system.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.4
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• pp.169-175
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• 2001

Ozone has been widely applied to many industrial fields because of its strong oxidation power, Therefore, the studies have been carried out for the methods on an effective and high concentration ozone generation. The silent or surface discharge type ozone generators have been mainly used for high concentration ozone generation in many fields of applications. But these two types of ozone generators have shortcomings to be improved. In this study, the ozone generator which improved the shortcomings of above ozone generators was proposed and fabricated for the high concentration ozone generation. And the proposed ozone generator could generate the surface and barrier discharge simultaneously. For this purpose, a mesh type discharge electrode was proposed and studied as a function of the widths output maximum ozone concentration of 2.96[vol%] was obtained at 5.6[kV], 830[mA], for 0.3[mm] width and 0.8[mm] vacancy of the mesh electrode and gap spacing of 0.65[mm] respectively.

• Fire Science and Engineering
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• v.34 no.4
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• pp.1-6
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• 2020

In this study, the authors measured voltage and current waveforms in real time during a serial arc discharge. The analysis results of the arc discharge radiation patterns exhibited intermittent discharge, arc growth, creation of a heat generating area, occurrence of plume, and formation of a red heat area, which proceeded in that order. When the serial arc discharge was introduced, the current and voltage waveforms exhibited periodicity as sine waves. It was also observed that a restriking transient voltage occurred when the waveform changed from positive (+) to negative (-) and vice versa. When the discharge proceeded, the amount of heat generated for 1 s and 600 s was approximately 0.317 mJ, and 190 mJ, respectively. The duration of the short circuit was approximately 1.66 ms, and in the case of the voltage waveform, it was evident that the electric potential increased to 49.9 V in the same cycle. Furthermore, when the discharge proceeded, the effective value (RMS value) of the current was approximately 1.72 A with a maximum current of approximately 2.53 A, whereas the effective value of the voltage was approximately 42.8 V with a maximum of approximately 208 V.

• Journal of the Korean Society of Safety
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• v.15 no.3
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• pp.66-70
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• 2000

In order to cope with environmental problems caused by harmful gases emitted from various industrial sources, a new technology which employs discharge plasma formed in ordinary atmospheric pressure has been intensively investigated in many industrialized nations. Although a plenty of useful outcomes and suggestions have been made public by scientists in this field, few commercial products which effectively decompose pollutant gases have appeared as yet. This is partly because that the energy efficiency of a most effective plasma reactor has not reached a satisfactory level in comparison with those of devices using conventional technologies. In an attempt to solve the problem mentioned above, we noticed to combine heterogeneous electrical discharges. This concepts is based on that each plasma reactor has its specific spatial region in which chemical reaction are active and by electrically affected with another reactor of different type, the activated region would increase - which may lead to cutting down the energy consumption. To prove this concept experimentally, two different discharge equipments, a plane ceramic-based surface discharge electrode and a corona electrode with tungsten needle may, are selected and combined to fabricate a hybrid plasma reactor. The results are summarized as follows; (1) Ozone concentration generated in the plasma region drastically increases when the positive corona discharge is added to the surface discharge. The rate of increase of ozone depends on the frequency of the surface discharge. The negative corona, however, does not contribute to the improvement of the ozone generation. (2) NO(nitrogen monoxide) decomposition rate also improves by simultaneously applying the surface and the positive corona discharges. The effect of the corona superposition is more evident when the level of the surface discharge is moderate. (3) By adjusting the corona level, the net energy efficiency during NO decomposition improves in comparison with the simple surface discharge reactor.

• Journal of Korea Water Resources Association
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• v.38 no.6 s.155
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• pp.485-494
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• 2005

It is very important to analyze the correlation between discharge and water quality. The observation of discharge and water quality are effective at same point as well as same time for real time management. But no less significant is the fact that there are some of real time water quality monitoring stations far from the T/M water stage. Pyeongchanggang station is one of them. In this case, it need to observe accurate discharge data, and to develop forecasting program or system using real time data. In this paper, discharge on Pyeongchanggang station was calculated by developed runoff neural network model, and compared with discharge using WMS(Watershed Modeling System) model. WMS shows better results when peak discharge is small and hydrograph is smooth. Forecasted discharge of neural network model have achieved the highest overall accuracy of specific discharge and WMS. Neural network model forecast change of discharge well on unrecored station.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.6
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• pp.773-778
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• 2011

The International Maritime Organization(IMO) could try to adopt more severe amendment to prevent any air pollution from various waste materials by marine incinerator. This study is to analyse the performance improvement through Ansys CFD about new invented system which has three flue-gas discharge channels and sub-ejector installed in the dischage channel in order to evacuate flue-gas well from the combustion chamber. The results showed that the discharge temperature of flue-gas was below the regulated value of IMO by the multi-channels, and the sub-ejector system installed in the discharge channel was highly effective one to improve the flue-gas discharge ability.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1562-1563
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• 2011

Partial discharge measurement is one of the effective diagnostic techniques to predict abnormal high voltage dielectric insulation conditions of the electric equipments. Recently partial discharge diagnostic techniques were also utilized to evaluate the cryogenic dielectric insulation of high temperature superconducting electric equipment in liquid nitrogen. Generally, liquid nitrogen at 77 K is used used as the cryogenic and dielectric media for many high temperature superconducting high voltage applications. When a quench in the superconductor occurs, bubbles are generated which can affect the dielectric properties of the liquid nitrogen. So in order to reduce the bubble formation, subcooled nitrogen was also employed for this purpose. In this work, investigation of partial discharge characteristics of subcooled liquid nitrogen were conducted in order to clarify the retardation of partial discharge initiation voltage according to the different subcooling temperature of liquid nitrogen. And also the relation of partial discharge phenomena and the activities of bubbles were analyzed. It was observed that PD inception voltages shows rather different characteristics according to the decrease of subcooling temperature and the activities of bubbles were strongly influenced by temperature of the subcooled liquid nitrogen.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.12
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• pp.2256-2261
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• 2010

A corona discharge system with needle point or wire type corona electrode has been well used as an ionic wind blower. The corona discharge system with a needle point electrode produces ions at lower applied voltage effectively. However, the corona discharge on the needle point electrode transits to the arc discharge at lower voltage, and it is hard to obtain the elevated electric field in the discharge airgap for enhancing the ion migration velocity due to the weak Coulomb force. A cylindrical corona electrode with sharp round tip is reported as one of effective corona electrode, because of its higher breakdown voltage than that of the needle electrode. A basic study, for the effectiveness of cylindrical electrode shape on the ionic wind generation, has been investigated to obtain an maximum wind velocity, which however is the final goal for the real field application of this kind ionic wind blower. In this paper, a parametric study for maximizing the ionic wind velocity utilizing the cylindrical corona electrode and a maximum ion wind velocity of 4.1 m/s were obtained, which is about 1.8 times higher than that of 2.3m/s obtained with the needle corona electrode from the velocity profile.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.4
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• pp.39-46
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• 2005

This research concerns the ADS drive method of 3 electrodes AC PDP and is determined the minimum pulse width of the address and the sustain, which the steady sustain discharge without decreasing luminance can be obtained. From the experimental result, if the address pulse width became $1.5[{\mu}s]$ or more a effective address discharge with the operating margin of 35[V] was possible. And if the sustain pulses width became $2[{\mu}s]$ or more, a steady sustain discharge with the operation margin of 25[V] was possible. When this condition is applied to Full-HDTV class PDP with the in lines of horizontal scanning lines, 8 sub-fields and total 1420 sustain pulses can be used.