• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.1
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• pp.114-122
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• 2014

This paper describes a study of the design conditions of a planar surface dielectric barrier discharge (DBD) reactors for generating negative air ions. The capacity of negative air ion generated by the surface DBD reactor is affected by the shape, area ratio and the location of the discharge and induction electrodes of it. To study the optimal design conditions of DBD reactors, the electrodes printed on the substrate of a PCB board is utilized to conduct kind of experiments: the distance of the each electrode along with the X-Y axis, the area ratio of the discharge electrode to induction electrode, and the symmetrical and asymmetrical location of two electrodes. The ion generation capacity is inverse proportional to the gap increases along with X-Y axis. And the optimum ion concentration generated by the ionizer was inspected when the electrodes area ratio was 3 and 5 times of the symmetrical and asymmetrical experimental condition respectively.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1400_1401
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• 2009

In this paper describes the comparisons of the surface flashover characteristics according to the change of the insulation media by experimental GIS(Gas Insulated Switchgear) chamber in accordance with change of pressure(P) and electrode distance(d). The using insulation medias are $SF_6$, Dry-Air, I-Air(Imitation Air, $N_2$ : $O_2$ = 79[%] : 21[%]), $N_2:O_2$ mixture gas and pure $N_2$. In this study, in order to compare the properties $SF_6$ and order insulation gas, we investigated the properties of the various insulation media with a knife to knife electrode under ac high voltage application. The gas pressure was changed from 1 to 5[atm]. as a result, it was found that dielectric strength is $SF_6$ > I-Air > Dry-Air and the best environmental preservation gas is Dry-Air.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1181-1187
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• 2015

Sulfur hexafluoride (SF₆) gas is used widely in electric power equipment such as Gas Insulated Switchgear (GIS), Gas Insulation transmission Line (GIL), and Gas Circuit Breaker (GCB). But applications of SF₆ should be restricted because SF6 gas is one of the greenhouse effect gases. To reduce use of SF₆ gas, a study on eco-friendly alternative insulation medium is needed. In this paper, we investigated lightning impulse (LI) breakdown of dry-air which is attracting attention as an ecofriendly alternative gas and the LI breakdown of hybrid insulation combined with dry-air and solid insulation (Room-Temperature Vulcanizing Silicone Rubber-RTV SIR) and dry-air in inhomogeneous fields according to gap distance and pressure. The experiment results showed that the LI breakdown strength of hybrid insulation system was higher than that of dry-air insulation system. It was verified that the development of technology related to eco-friendly power apparatus compact such GIS, GCB and GIL can be used as basic research data.

• Electrical & Electronic Materials
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• v.10 no.3
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• pp.233-238
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• 1997

We have investigated gas-detection characteristics of CuTBP (Copper-tetra-tert-butylphthalocyanine) chemiresistor devices exposed to air/200ppm N $O_{2}$ gases. The CuTBP films were made by Langmuir-Blodgett (LB) techniques. Sensitivity, response time, recovery time, and reproducibility of the devices were measured by current voltage characteristics. Interdigital electrode was used to improve the sensitivity. It was observed that a conductance G increases monotonically as the number of interdigital electrode finger pairs increases. As the number of interdigital electrode finger pairs increases, the sensitivity S( $G_{gas}$/ $G_{air}$) increases more than 50 times and stable. But the response time was delayed. The average recovery time of the CuTBP chemiresistor devices turned out to be about 100 second. We have also investigated applicability of the CuTBP chemiresistor device for a gas sensor.sor.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2214-2216
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• 2005

This paper is researched discharge and ozone generation characteristics of ozonizer using $Al_2O_3$ Ceramic dielectric. The discharge characteristics with variation of the discharge electrode area is studied. The characteristics of ozone concentration. ozone generation and ozone yield were measured to discharge power, discharge electrode area and supplied gas flux for oxygen and air. The solubility of ozone for water concentrations and ozone generations proportional to discharge power and discharge electrode area. Ozone yield has slowly increase with Increasing discharge power at high flow-rate. As the result, the maximum values of ozone characteristics ozone generation and ozone yield, can be obtained 5817[ppm] and 36[g/kWh]. We make enough the ozone concentration as the air in the home. An electric discharge electrode area is apt to shrink gradually into a miniaturization trend of the ozonizer but the enlargement of the occurrence flight of the electric discharge area gives the characteristic enhance the aid in the identity condition through the structure improvement.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.10
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• pp.908-913
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• 2004

This study investigates the effect of the wave form of pulse energization and dust concentration on the collection characteristics of a moving electrode electrostatic precipitator (MEEP). Under the same specific corona power, the collection efficiency of the MEEP for the lower dust concentration ($2g/m^3$) becomes higher than that for the higher concentration ($10g/m^3$). Both the collection efficiency and specific corona power increase with increasing pulse period for the same value of applied voltage. The collection efficiency of MEEP is higher than that of the conventional fixed plate electrode electrostatic precipitator.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.5
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• pp.1005-1010
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• 2011

The accidents caused by dielectric instability have been increasing in power grid. It is important to enhance the dielectric reliability of a high voltage apparatus to reduce the damage from electrical hazards. To develop an electrically reliable high voltage apparatus, the experimental study on the electrical breakdown field strength is indispensable, as well as theoretical approach. In this paper, the lightning impulse breakdown characteristics considering utilization factors are studied for the establishment of insulation design criteria of an high voltage apparatus. The utilization factors are represented as the ratio of mean electric field to maximum electric field. Dielectric experiments are performed by using several kinds of sphere-plane electrode systems made of stainless steel. As a result, it is found that dielectric characteristics are affected by not only maximum electric field intensity but also utilization factors of electrode systems. The results are expected to be applicable to designing the air-insulated high voltage apparatuses.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1865-1867
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• 2005

Film bulk acoustic resonator (FBAR) devices which adopt an air-gap type (metai/AlN/metal/air/substrate) configuration are fabricated by a novel process. The newly fabricated resonator doesn't employ any supporting layer below it. FBAR devices with the air-gap type are also fabricated using the conventional method. The frequency response characteristics of all the devices fabricated are measured and compared, in terms of the kinds of top and bottom electrode materials. The results show that the better device performance of FBAR devices can be achieved by employing the proposed process.

• Korean Journal of Metals and Materials
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• v.49 no.11
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• pp.839-844
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• 2011

We examined the effects of alloying elements such as Fe, Ga, In, Sn, Mg, and Mn on the electrochemical characteristics of Al-based alloys for Al-air batteries by potentiodynamic polarization tests and electrochemical impedance spectroscopy. The corrosion potential of an Al anode was lowered by the addition of Ga and Sn, resulting in an increase in the cell voltage compared with a pure Al electrode. Fe was not beneficial to improve the electrochemical properties of the Al anode in that it caused a decrease in the cell voltage and reduced corrosion rate slightly. In, Mn, Sn, and Mg decreased the corrosion rate of the Al alloys, while Ga enhanced corrosion significantly and accelerated consumption of the anode.

• Journal of Ocean Engineering and Technology
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• v.14 no.4
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• pp.56-61
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• 2000

This study has been performed for mechanical properties of underwater wet welding electrode with rolled steel (KR-RA) for ship structure, one kind (E 4313) of domestic covered arc welding electrode used in the air and two kinds (UWE-01, UWE-02) of underwater covered arc welding electrode experimentally developed on the same welding condition. The results obtained were as follows : The hardness value of underwater covered arc welding electrode (UWE-01) was about 8.3% lower than domestic covered arc welding electrode(E 4313) in heat affected zone of test of UWF-02 was lower about 4.5%. Tensile strengths of UWE-01 were about 0.9%, and those of UWE-02 were about 6.5% higher than those of domestic covered arc welding electrodes (E 4313) in test specimens. The impect value of UWE-01 were about 15.5%, and those of UWE-02 were about 21.7% highter than those of domestic covered arc welding electrodes(E 4313) in test specimens. So mechanical properties of the underwater arc welding electrode were improved by the composition ratios of covering materials.