• 전기의세계
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• 제18권1호
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• pp.7-10
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• 1969

This paper shows theoretically the possibility of raising up the flash over voltage in suspension insulators or bushing according to the results which was gotten by previous study done by the Author. If some conducting metallic barriers are inserted into the flash over discharge path, the flash over voltage is forund to be increased condiferablly. Applying this priciple, some methods of improving flash over characteristics are discussed theoretically.

• 전기의세계
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• 제17권3호
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• pp.7-28
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• 1968

When a insulator plate is inserted to the discharge path of a space discharge gap in which the field strength is not uniform, the spark voltage under the atmospheric pressure between the electrodes decreases or rises according to the position of the insulating plate. Also it is reported that if a metallic barrier plate is inserted to the discharge path of the same space discharge gap, similar variations of spark voltage are found. Speaking briefly, mensioned above are the spark voltage characteristics when an insulator or metallic barrier is inserted to the space discharge gap. Also some experimental results, concerning to the surface creepage flash over characteristics at the case when an insulator barrier is inserted to the discharge path of a surface creepage discharge gap, were reported by Peek. But up to now there are no reports on surface flash over voltage characteristics at the case when a metallic barrier is inserted to the surface creepage gap. In this study the effects of a conducting metallic barrier inserted to the path of a surface creepage discharge gap on the flash over voltage characteristics are investigated theoretically and experimentally, and got some important results, clearing the effects of the position and width of a conducting barrier is inserted, the surface flash over voltage characteristics appear as an Inverse N or W Characteristics. Such theoretical or experimental results may have some relation not only with the effects of dry belt and snow on suspension insulators, but also with the effects of dirty zone or water drops on the surface creepage flash over voltage.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1536-1539
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• 1994

The influence due to metallic particle contaminated on spacer surface is remarkable in the decreasing of dielectric strength in $SF_6$ GIS. In relation with this problem, We studied, AC flash-over voltage characteristics and breakdown mechanism are investigated under metallic particle initiated condition in $SF_6$ gas by varying the particle position, particle shape with a plane-plane electrode. The main results arc as follows 1. The small amount of the metallic particle in the gap do not make flash-over voltage to be influence, but the significant decrease of th flash-overed voltage is result in case of the big and long size of the metallic paraticle. 2. Influence of the flash-over voltage are lowest in the mid and are highest in the electrode of metallic particle position. 3. In case of the initiated metallie particle, The more the pressure are high, the more the recluced ratio of flash-over voltage are high. 4. The metallic particle shape which results in the reduced flash-over voltage forced the critical pressure to move in to the region of low pressure. 5. The existance of the metallic particle on the upper electrode side and high pressure make the decreasing ratio of flash-over voltage bigger than that of the ground side electrode.

• 대한안전경영과학회지
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• 제5권1호
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• pp.1-12
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• 2003

In this paper, computer simulation was used for researching into the estimate of flash over result from compartment fire and the characteristics operation of sprinkler RTI. Computing simulation, we analyzed and verified the path of the flame in compartment fire and the adaptation of sprinkler system concerned with sprinkler RTI.

• 전기의세계
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• 제14권2호
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• pp.8-13
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• 1965

It is expected that the impurities contained in a solid state insulation material will affect a considerable influence on its break-down voltage, dielectric loss, and insulation resistance. In this thesis, as a preliminary experimental research for the investigation described above, the effect of metalic barrier between the electrodes on the creepin flash over discharge voltage along the surface of a solid insulation material has been investigated, and got some interesting results. It was found that generaly the flash over voltage rises when a metalic barrier is located between the electrodes. The results of this investigation will be taken into account as an important components on the insulation design to prevent the creeping flash over discharge in insulators, bushings, and so on.

• 조명전기설비학회논문지
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• 제12권1호
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• pp.3-11
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• 1998

스페이서 표면 파티클에 의한 오염의 영향은 SF6GIS의 절연내력을 현저히 감소시킨다. 이와 관련해서 우리는 평행평판전극 구성으로 SF6가스중에서 금속 및 비금속 파티클의 위치 및 형태를 변화시키면서 교류전압에서 섬락전압 특성과 파괴 기구에 대해서 연구했다. 주된 결과는 $\circled1$파티클 위치에 대한 섬락전압 감소의 영향은 갭중간에서 가장 적고 전극에서 미소간극 분리된 경우의 영향이 가장 커다. $\circled2$ 섬락전압 감소가 크게 되는 금속 파티클 일수록 FOV 포화 현상은 낮은 압력 영역으로 이동된다. $\circled3$0.6[mm]이하의 비금속 파타클은 섬락전압에 그의 영향을 미치지 않는다.

• 한국방재학회 논문집
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• 제10권4호
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• pp.81-88
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• 2010

최근 들어 기상 이변에 따라 단시간 동안에 특정 소유역에 집중하는 호우 또는 초과우량에 의한 국지성 돌발홍수가 빈번히 발생함에 따라, 이로 인한 인명과 재산의 상당한 위험과 손실은 전 세계적인 것으로서 우리나라도 증가일로에 있다. 돌발홍수는 일반적으로 급경사 소유역에서 집중적인 강우에 의해 발생하여 빠른 유출과 토석류를 동반하기 때문에, 홍수피해를 대비하기 위한 사전 홍수예보시간이 부족할 정도로 급격히 빠른 홍수의 특성을 보인다. 본 연구의 목적은 대상유역의 확률강우량으로부터 돌발홍수지수(flash flood index, FFI)를 산정하여 돌발홍수의 심각성 정도를 정량적으로 분석하고자 한다. 특히 미계측 유역하천에서의 지역 홍수예 경보를 위한 기초자료를 제공할 수 있도록, 대상유역에 대하여 상대적인 돌발홍수심도를 제시할 수 있는 FFI-D-F(돌발홍수지수-지속시간-빈도) 관계곡선을 개발하였다. 또한 FFI-D-F 관계곡선은 현존 및 계획 방재시설물의 돌발홍수 대응능력 및 잔여홍수위험 평가에 활용될 수 있을 것으로 기대된다.

• 한국게임학회 논문지
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• 제5권3호
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• pp.11-16
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• 2005

최근 모바일 휴대 단말기의 성능 향상과 사용자의 멀티미디어 서비스에 대한 요구 수준이 높아짐에 따라 모바일 휴대 단말에서 다양한 멀티미디어 응용 프로그램들이 개발/서비스되고 있다. 본 논문은 현재 모바일 환경에서 대표적인 멀티미디어 서비스의 하나인 Mobile Flash를 하드웨어 리소스 제약이 많은 모바일 환경에서 설계 및 구현한 것에 관하여 기술한다. Mobile Flash는 유선 데스크탑 환경에서 이미 전세계의 95% 이상 보급/설치되어 애니메이션, 게임, 교육용 컨텐츠, 광고 등 다양한 컨텐츠를 재생을 지원하는 Flash Player를 모바일 환경에 맞도록 최적화한 것이다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.138-138
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• 2021

Flash floods are one of the types of natural hazards which has severe consequences. Flash floods cause high mortality, about 5,000 deaths a year worldwide. Flash floods usually occur in mountainous areas in conditions where the soil is highly saturated and also when heavy rainfall happens in a short period of time. The magnitude of a flash flood depends on several natural and human factors, including: rainfall duration and intensity, antecedent soil moisture conditions, land cover, soil type, watershed characteristics, land use. Among these rainfall intensity and antecedent soil moisture, play the most important roles, respectively. Flash Flood Guidance is the amount of rainfall of a given duration over a small stream basin needed to create minor flooding (bank-full) conditions at the outlet of the stream basin. In this study, the Sejong University Rainfall-Runoff model (SURR model) was used to calculate soil moisture along with FFG in order to identify flash flood events for the Geum basin. The division of Geum river basin led to 177 head-water catchments, with an average of 38 km². the soil moisture of head-water catchments is considered the same as sub-basin. The study has measured the threshold of flash flood generation by GIUH method. Finally, the flash flood events were used for verification of FFG. The results of the validation of seven past independent events of flash flood events are very satisfying.

• 한국농공학회논문집
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• 제65권3호
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• pp.57-67
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• 2023

A flash drought is a rapid-onset drought that develops over a short period of time as weather and environmental factors change rapidly, unlike general droughts, due to meteorological abnormalities. Abnormally high evapotranspiration rates and rapid declines in soil moisture increase vegetation stress. In addition, crop yields may decrease due to flash droughts during crop growth and may damage agricultural and economic ecosystems. In this study, Flash Drought Intensity Index (FDII) based on soil moisture data from Gravity Recovery Climate Experiment (GRACE) was used to analyze flash drought. FDII, which is calculated using soil moisture percentile, is expressed by multiplying two factors: the rate of intensification and the drought severity. FDII was developed for domestic flash drought events from 2014 to 2018. The flash drought that occurred in 2018, Chungcheongbuk-do showed the highest FDII. FDII was higher in heat wave flash drought than in precipitation deficit flash drought. The results of this study show that FDII is reliable flash drought analysis tool and can be applied to quantitatively analyze the characteristics of flash drought in South Korea.