• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.468-469
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• 2007

$SF_6$ gas used widely as insulating component in electric power industry has excellent in insulation and arc extinguishing performance in gas-insulated switchgear. However, the concern about eco-friendly alternative gas is currently rising, because $SF_6$ gas is one of the main greenhouse gases. As one of the study for $SF_6$ free technology, composite-insulation technology is focused in this paper. To analyze the influence by epoxy thickness change, the composite-insulation composed of dry-air and epoxy was used in this paper. To analyze AC breakdown by the epoxy thickness, needle-plane electrode was used and needle was molded by epoxy. Under the gas pressure ranged from 0.1 to 0.6MPa, the breakdown voltage of dry-air were measured in AC electric field. The data of composite-insulation were acquired by changing the thickness of epoxy used in each composite-insulation under the same condition.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1389-1390
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• 2007

SF6 gas used widely as insulating component is rising as the environment problem. Electrical breakdown characteristics of epoxy and dry-air composite insulation was investigated on thickness of epoxy and pressure of dry-air under non-uniform field. The gap of needle to plane was from 2mm to 5mm. The pressure of dry-air was varied within the range of $0.1{\sim}0.6$ MPa. The thickness of a needle was 1mm and the curvature radius of a needle end was 100um. The diameter of a plane made of the stainless steel was 50mm. As a result of the experiment, breakdown voltage was increased about 3 times when epoxy was used. The impact that the thickness of epoxy influences on breakdown voltage was poor. It needs suitable thickness computation because the insulating gap of the gas is short as epoxy thickness increases.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.113-114
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• 2008

The purpose of this paper is to analyze AC Breakdown of solid/air composite insulation depending on the thickness and the pressure of dry air for eco-friendly insulation. SF6 gas has been widely used in electric equipment as gas insulation because of high dielectric strength and arc extinguishing performance. However, because SF6 gas is one of the green house effect gases, alternative insulation such as SF6 mixture, extremely low temperature gas, vacuum, liquid and solid insulating are being investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.289-290
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• 2008

The purpose of this paper is to analyze AC Breakdown of solid/air composite insulation depending on the thickness and the pressure of dry air for eco-friendly insulation. SF6 gas has been widely used in electric equipment as gas insulation because of high dielectric strength and arc extinguishing performance. However, because SF6 gas is one of the green house effect gases, alternative insulation such as SF6 mixture, extremely low temperature gas, vacuum, liquid and solid insulating are being investigated.

• Journal of Periodontal and Implant Science
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• v.16 no.1
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• pp.93.1-93.1
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• 1986

• Proceedings of the Korean Information Science Society Conference
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• 2007.06a
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• pp.23-24
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• 2007

• Journal of the Korean Society of Food Science and Nutrition
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• v.4 no.1
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• pp.7-12
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• 1975

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.08a
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• pp.11-11
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• 2020

Background : The genus Cypripediums are typically adapted to the low temperature and cold climates of the high land in Korea. The species which were reported in Korean peninsula are C.japonicum, C.macranthos, C.calceolus and C.guttatum. We had already reported the successful germination of the C.macranthos and C.guttatum. The small spotted lady's slipper orchid(C.guttatum) is most endangered plants to extinction of which population was reported less than 100 in Korea. The objective of the present research is restoration of the C.guttatum in ex situ and adaptation in high land and nursery. Methods and Results : The 350 seedlings of C.guttatum were transplanted in soil at alpine area(altitude 750m) and the nursery of Korea National Arboretum(KNA) in YangPyeong city on May 2019 and 2020 in order to verify the possibility of ex situ restoration. The sprouted ratio of the seedlings were less than 10% in the alpine area and 83% in the nursery of KNA. The reasons of the diverse survival ratio are presumed as the low moisture content in the soil and heavy shade of the alpine area. The 15 cypripedium species and 29 hybrids were also effectively adapted in the KNA rare plant garden. Conclusion : These results demonstrated the difficulties of the restoration for small spotted lady's slipper orchid in the natural habitation. From the above results, we may conclude that the critical factors of the genus Cypripedium are intensive care for the fragile seedlings during the 1^st year acclimatization.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.334-335
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• 2006

Solid insulation exposed to voltage is degraded by electrical tree process. And the degradation of the insulation is accelerated by voltage application. For this experimental, specimen of electrical tree model is made by XLPE (cross-linked polyethylene). And the size of the specimen is 7*5*7 $mm^3$. Distance of needle and plane is 2 mm. Voltages applied for acceleration test are 12 kV to 15 kV. And distribution characteristic of degraded stage is studied too. As a PD detecting and data process, discharge data acquire from PD detecting system (Biddle instrument). The system presents statistical distribution as phase resolved. Moreover the processing time of electrical tree is recorded to know the speed of degradation according to voltage.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.215-216
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• 2006

Solid insulation exposed to voltage is degraded by electrical tree process. And the degradation of the insulation is accelerated by voltage application. For this experimental, specimen of e1ectrical tree model is made by XLPE (cross-linked polyethylene). And the size of the specimen is $7*5*7\;mm^3$. Distance of need1e and plane is 2 mm. Voltages applied for acceleration test are 12 kV to 15 kV. And distribution characteristic of degraded stage is studied too. As a PD detecting and data process, discharge data acquire from PD detecting system (Biddle instrument). The system presents statistical distribution as phase resolved. Moreover the processing time of electrical tree is recorded to know the speed of degradation according to voltage.