• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.2
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• pp.93-101
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• 2016

This paper presents the surface discharge characteristics in Dry-Air on laminated epoxy solid dielectrics and conductive particles in order to provide the valuable information for the insulation design of eco- friendly gas insulated switchgear. To improve insulation performance, the three types of the laminated epoxy solid dielectrics were proposed, and it was revealed that their surface discharge characteristics were similar to the bakelite dielectrics of same-laminated types. From the surface discharge characteristics of dry air, it was demonstrated that the effect of conductive particles on surface discharge voltage was dominant when there are this particles at the shortest electrode gap and that the degradation of insulation performance on the conductive particles was evident in epoxy than teflon. These phenomena were interpreted in terms of particle-triggered discharge mechanism and electric field of triple junction, respectively.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.2
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• pp.44-48
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• 2004

A silent type ozone generator using water surface electrode was proposed. And it was investigated experimentally that a variation of water conductivity affected to water surface discharge. Important factors affecting to water surface discharge are ions in discharge space and ions and polarized molecules in water and so on. In this study, It was intended to change the characteristics of discharge by controlling the number of ions in water. The number of ions in water could be controlled by changing the water conductivity. Water conductivity was controlled by quantity of inserted NaCl to distilled water. At this time, current-voltage characteristics and characteristics of ozone generation quantity were investigated in each case. As a result, when NaCl was inserted in distilled water, more stable discharge was generated. As the quantity of NaCl was increased, discharge starting voltage could be lowered.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.4 no.3
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• pp.5-12
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• 2005

In wire discharge machining which is using STD 11 as die materials, the major factors of machining speed are discharge voltage, discharge current, and discharge time. All of the three factors give the effect. Increasing of the discharge pulse time gets groove width wider and it relatively increases surface roughness and clearance. If no load voltage is decreased, surface roughness is good but it decreases machining speed. If on time is increased, machining speed will get faster and clearance and offset value also get bigger.

• Journal of the Korean Society of Industry Convergence
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• v.15 no.2
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• pp.49-54
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• 2012

With the improvement of industrial society, the high quality electrical energy, simplification of operation and maintenance, ensuring reliability and safety are being required. This paper reviews a basic data of the surface discharge characteristics for teflon resin in not only pure $N_2$, $N_2:O_2$ mixture gas and Dry-Air as being focused on environmentally friendly insulating Gas also $SF_6$. Used electrodes are Knife to Knife. With the changing distance of electrodes and pressure, we can find it, surface discharge voltages and surface dielectric strengths, respectively. Surface discharge Voltages of $N_2:O_2=80:20$ mixture gas are more higher than the $N_2:O_2$ Mixture gases.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.8
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• pp.696-701
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• 2005

This paper was investigated the changes of surface properties of high-temperature-vulcanized (HTV) semiconductive silicone rubber due to oxygen plasma discharge. The modifications produced on the silicone rubber surface by oxygen plasma were accessed using Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS), contact angle and Surface Roughness Tester. The results of the chemical analysis Showed that C-H bonds were broken due to plasma discharge and Silica-like bonds (SiOx, x=$3\~4$) increased. It is thought that the above changes lead to the increase of surface energy of high-temperature-vulcanized (HTV) semiconductive silicone rubber also, Surface roughness was increased with cleavage of side-chains and oxidation process, it confirmed change as the SEM. The micromorphology of surface and hydrophobicity due to plasma discharge based on our results were discussed.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.5
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• pp.385-390
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• 1999

Surface corona discharge characteristics of a dc corona charged ferroelectric pellet barrier have been investigated experimentally. Electric charges stored on the surfaces of the ferroelectric pellets by a dc corona discharge provide partial electric fields on the surfaces of the ferroelectric pellets, which could generate surface corona discharges on the ferroelectric pellets. This system utilizes both the surface discharges on the ferroelectric pellet barrier and the corona discharge between corona tip and mesh electrode. Positive and negative dc voltages were applied to the tip to generate partial discharges, and corona currents were estimated to investigate the buildup charge on ferroelectric pellets as a function of the applied time and the charge relaxation time constants of ferroelectric pellets. As a result, in the case of the negative corona discharge with the ferroelectric pellet barrier, the mean corona current and ozone generation increase greatly, and the surface discharges on the ferroelectric pellets can be fenerated efficiently. It is also found that, charge relaxation time, dielectric constants offerroelectric pellets, polarity of applied voltage and applied time affected to the surface discharges among the ferroelectric pellets.

• Korean Journal of Chemical Engineering
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• v.35 no.12
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• pp.2452-2463
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• 2018

Surface treatment of sol-gel bioglass is required to increase its biomedical applications. In this study, a dielectric barrier discharge (DBD) plasma treatment in atmospheric pressure was performed on the surface of [$SiO_2-CaO-P_2O_5-B_2O_3$] sol-gel derived glass. The obtained bioglass was treated by plasma using discharge current 12 mA with an exposure period for 30 min. The type of discharge can be characterized by measuring the discharge current and applied potential waveform and the power dissipation. Apatite formation on the surface of the DBD-treated and untreated samples after soaking in simulated body fluid (SBF) at $37^{\circ}C$ is characterized by Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), inductively coupled plasma (ICP-OES) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS). We observed a marked increase in the amount of apatite deposited on the surface of the treated plasma samples than those of the untreated ones, indicating that DBD plasma treatment is an efficient method and capable of modifying the surface of glass beside effectively transforming it into highly bioactive materials.

• Journal of Electrochemical Science and Technology
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• v.6 no.4
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• pp.131-138
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• 2015

Electrical discharge machining is an unconventional machining process in which successive sparks applied to machine the electrically conductive materials. Any changes in electrical discharge machining parameters lead to the pieces with distinct surface roughness. The electrical discharge machining process is well applied for high hardness materials or when it is difficult to use traditional techniques to do material removing. Furthermore, this method is widely applied in industries such as aerospace, automobile, molding, and tool making. CK45 is one of the important steels in industrial and electrical discharge machining can be considered as a proper way for its machining because of high hardness of CK45 after thermal operation of the electrical discharge machining process. Optimization of surface roughness as an output parameters as well as electrical discharge machining parameters including current, voltage and frequency for electrical discharge machining of CK45 has been studied using copper tools and kerosene as the dielectric. For such a purpose and to achieve the precise statistical analysis of the experiment results design of experiment was applied while non linear regression method was chosen to assess the response of surface roughness. Then, the results were analyzed by means of ANOVA method and machining parameters with more effects on the desired outputs were determined. Finally, mathematical model obtained for surface roughness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.199-202
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• 1999

The paper deals with the surface discharge characteristics for porcelain suspension insulators. The micro-crystals were crystallized on the surface of glace coated on the porcelain These micro-crystals may affect the electrical Properties such as flashover voltage. However. not much research have been conducted. In this study. we correlated the surface discharge characteristics to the microstructures. It was confirmed that the micro-crystals on the glaze initiated the flashover when the surface was wetted and/or contaminated.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1873-1875
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• 2003

Surface corona discharge characteristics of a ac corona charged ferroelectric pellet barrier have been investigated experimentally. Electric charged stored on the surfaces of the ferroelectric pellets by a at corona discharge provide partial electric fields on the surfaces of the ferroelectric pellets, which could generate surface corona discharges on the ferroelectric pellets. This system utilizes both the surface discharges on the ferroelectric pellet barrier and the corona discharge between wire electrodes. As a result, in the case of the corona discharge with the ferroelectric pellet barrier, the mean corona current and ozone generation increase greatly, and the surface discharges on the ferroelectric pellets can be generated efficiently. It is also found that, the ferroelectric pellet barrier discharge reactor had better discharge characteristics for plasma generation than the wire-to-wire discharge reactor without pellets.