• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1478-1480
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• 1998

Inception and propagation of electrical tree and properties of partial discharge(PD) pulses accompanying with tree in low density polyethylene were discussed. We observed the characteristics of process of electrical tree by using optical microscope and investigated the statistical characteristics of the PD pulses by analyzing PD quantities and distribution patterns. The PD pulses were analyzed by q-n, $\phi$-n and $\phi$-q distribution. The statistical operators used were skewness(s), kurtosis(k) and average phase angle. The skewness and average discharge phase angle of PD pulses increased as the Propagation of tree. The kurtosis was about 1.8 at the Inception of tree, but It increased as the propagation of tree.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.531-535
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• 2000

This study was carried out to investigate water quality of streamflow in a forest land. We measured discharges and the concentration of streamflow for T-N, T-P, COD, cations(Na$\^$+/, K$\^$+/, Ca$\^$2+/, Mg$\^$2+/), and anions(CI$\^$－/, SO$\_$4/$\^$2-/). The average concentration of pollutants were extremely low, such as 0.4mg/$\ell$ for T-N, 0.02 mg/$\ell$ for T-P and 2.68mg/$\ell$for COD. The concentration of cations have a tendency to decrease with increasing discharge, while the concentration of SO$\_$4/$\^$2-/) increase with increasing discharge. It was found that the average concentration of Ca$\^$2+/ was highest and that of K$\^$+/ was lowest among cations.

• Journal of the Korean Ceramic Society
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• v.24 no.4
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• pp.392-396
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• 1987

Pure barium titanate was sintered at $1340^{\circ}C$ for 2, 4, 8, 16 hr to control their grain size. The measurements of breakdown strength and partial discharge characteristics were performed under rising AC voltage(60Hz). With increase of sintering time, the average grain size was increased and breakdown strength was slightly decreased. Partial discharge in pores was observed under high voltage, and a model of dielectric break down in barium titanate ceramics is proposed.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.12
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• pp.568-572
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• 2003

A longitudinal discharge heated copper vapor laser with internal diameter 28 mm and discharge length 1.3 m has been constructed and tested. At the discharging voltage 15.2 kV, pulse repetition rate 10 kHz, buffer gas pressure 40 mbar, and internal temperature of the laser plasma tube $1520^{\circ}C$, it delivers more than 30 W average laser outputs.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.9
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• pp.1297-1301
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• 2013

This paper analyzes of PD occurrence position through an analysis of the arrival time difference between the GIS partial discharge signal. Because of GIS (Gas Insulated Switchgear) is a facility very important power equipment and as part of the equipment that make up the power system, the stabilization of the power industry, which accounted for 88.5% share of GIS substation in the form of a substation is an important equipment for power supply. In the situation where we are gradually expanding the need for preventive diagnosis in order to improve the efficiency of equipment management and failure prevention for Preventive diagnosis. In this paper as a method for extracting pre-defect of failure of GIS Apply the average value method of calculating the 5 times each using a pulse of the first time of the second pulse (${\Delta}t$) with an oscilloscope generation position PD(Partial Discharge). the results of GIS internal inspection, the partial discharge of the actual the position of the partial discharge was confirmed with an accuracy of about 82% of positions. Arrival time difference in the most effective manner if the partial discharge of GIS internal occurs by applying the averaging method and TOA(Time of arrival) method, the partial discharge occurs you through the measurement and analysis of PD signal occurs was confirmed in the experiment are presented and diagnostic methods location tracking.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1621-1623
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• 1999

Recently, high voltage outdoor ploymer insulators have been widely used commercially owing to their excellent electrical and mechanical properties, superior comtamination flashover performance, light weight, easy installation or handing, no maintenance during service, competitive price and so on. compared to porcelaain and glass insulators. For instance, silicone rubber(SR) for polymeric insulators specially has much superior insulating and anti-pollution performance due to its specific hydrophobicity even in severe contaminated environments. We have investigated surface discharge current characteristics of silicone rubbers(SR) for HV outdoor composite insulation specimen under accelerated aging codition using a computer measuring system. The relations of average leakage current and surface discharge current repetition rates and discharge current amplitude, the distribution of discharge current amplitude were studied to investigate electrical conduction of silicone rubber surface with the salt fog condition.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.4
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• pp.387-394
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• 2009

Marine algal flora and community structure were examined seasonally at four study sites around Taean Power Plant, Korea from Jan. to Nov. 2006. A total of 73 algae species (12 green, 9 brown, 52 red) and 1 marine plant were identified. The number of species was maximal at the power plant Discharge (57 species) site followed by Hakampo (46 species), Intake (28 species) and Breakwater (15 species) sites during the study period. The average biomass in dry weight varied from 13.12g/m2 at Intake to 69.60g/m2 at Hakampo. Dominant and sub dominant species in terms of biomass were Gelidium divaricatum - Ulva pertusa at Intake, Chondria crassicaulis - Ulva pertusa at Discharge, Corallin a pilulifera - Chondrus ocellatus at Breakwater, and Corallina pilulifera - Sargassum thunbergii at Hakampo. Species richness of warm tolerant and green algae were greater at Discharge site than Hakampo, showing similar species richness. However, community indices were not distinguishable between Discharge and other study sites. In conclusion, species richness and biomass of seaweeds were greater at Discharge site compared to intake and breakwater sites, and the abundance of warm tolerant and green algal species were higher than Hakampo.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.246-248
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• 2002

This paper presents a high-frequency voltage source inverter for silent corona discharge ozonizer application, which is characterized by the power control based on pulse density modulation (PDM). The PDM inverter produces either a square -wave ac-voltage state or a zero-voltage state at its ac terminals to control the average output voltage under constant do voltage and operating frequency. This results in a wide range of power control in the silent corona discharge load with a strong nonlinear characteristics. And proposed addition circuit for maintain discharge on the center of the airgap. In this paper, schemed equivalent electric circuit of the discharge electrode for simulation. Finally, the effectiveness of this discharge tube character of silent corona ozonizer is investigated in the simulation results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.9
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• pp.1392-1401
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• 2017

In this study, the design methodology of pattern classification is introduced for avoiding faults through partial discharge occurring in the power facilities and local sites. In order to classify some partial discharge types according to the characteristics of each feature, the model is constructed by using the Radial Basis Function Neural Networks(RBFNNs) and Particle Swarm Optimization(PSO). In the input layer of the RBFNNs, the feature vector is searched and the dimension is reduced through Principal Component Analysis(PCA) and PSO. In the hidden layer, the fuzzy coefficients of the fuzzy clustering method(FCM) are tuned using PSO. Raw datasets for partial discharge are obtained through the Motor Insulation Monitoring System(MIMS) instrument using an Epoxy Mica Coupling(EMC) sensor. The preprocessed datasets for partial discharge are acquired through the Phase Resolved Partial Discharge Analysis(PRPDA) preprocessing algorithm to obtain partial discharge types such as void, corona, surface, and slot discharges. Also, when the amplitude size is considered as two types of both the maximum value and the average value in the process for extracting the preprocessed datasets, two different kinds of feature datasets are produced. In this study, the classification ratio between the proposed RBFNNs model and other classifiers is shown by using the two different kinds of feature datasets, and also we demonstrate the proposed model shows superiority from the viewpoint of classification performance.

• Atmosphere
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• v.30 no.2
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• pp.155-167
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• 2020

In order to produce more detailed and accurate information of river discharge and freshwater discharge, global high-resolution hydrodynamic model (CaMa-Flood) is applied to an operational land surface model of global seasonal forecast system. In addition, bias correction to grid runoff for the hydrodynamic model is attempted. CaMa-Flood is a river routing model that distributes runoff forcing from a land surface model to oceans or inland seas along continentalscale rivers, which can represent flood stage and river discharge explicitly. The runoff data generated by the land surface model are bias-corrected by using composite runoff data from UNH-GRDC. The impact of bias-correction on the runoff, which is spatially resolved on 0.5° grid, has been evaluated for 1991~2010. It is shown that bias-correction increases runoff by 30% on average over all continents, which is closer to UNH-GRDC. Two experiments with coupled CaMa-Flood are carried out to produce river discharge: one using this bias correction and the other not using. It is found that the experiment adapting bias correction exhibits significant increase of both river discharge over major rivers around the world and continental freshwater discharge into oceans (40% globally), which is closer to GRDC. These preliminary results indicate that the application of CaMa-Flood as well as bias-corrected runoff to the operational global seasonal forecast system is feasible to attain information of surface water cycle from a coupled suite of atmospheric, land surface, and hydrodynamic model.