• Journal of Advanced Marine Engineering and Technology
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• 제35권8호
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• pp.1063-1069
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• 2011

본 논문은 2 MW급 풍력터빈 3기로 구성된 6 MW 해상풍력발전단지의 풍력터빈 이격거리에 따른 공기역학적 출력 변화를 전산유동해석을 활용하여 연구한 것이다. 육상 뿐만 아니라 해상풍력발전단지에 있어서 레이아웃 설계는 풍력발전단지 초기 투자비, 년간 발전량 및 유지보수비에 영향을 끼치는 핵심 인자이다. 각 풍력터빈 로터에 대해서 모멘텀 소스를 가지는 액츄에이터 디스크가 아닌 완전한 3-D 모델에 대해서 전산유동해석 기법을 적용하여 연구하였으며 이는 기술적으로 큰 의미를 가진다. 본 논문의 연구결과는 향후 해상풍력발전단지 레이아웃 설계에 유용하게 적용될 수 있을 것이다.

• 대한기계학회논문집B
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• 제26권10호
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• pp.1355-1363
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• 2002

An experimental study was conducted to investigate the interaction phenomena of droplet array combustion in ambient environment. The droplet with 1 mm in diameter was supported from an optical fiber and ignited with a hot wire. Combustion lifetimes and burning rate constants were measured for fuel of nheptane according to parameters, which were junction and suspender spacings, and array configuration. Results show that the burning process considerably depends on the initial away configuration. The d$^2$-law is found to be correct when applied to both of the droplets in away and the single droplet. For separation distance of about 5mm, there exists a critical state. So the transition from a merged flame to separated flames occurs and burning velocity is much faster than before. Combustion lifetime of the lower droplet is shorter than that of the upper droplet in the two-dimensional arrays combustion. Burning rate constants of the droplets in arrays are smaller than that of the single droplet, while they become higher as separation distance increases. Combustion lifetimes of the droplets in arrays are longer than that of the single droplet and decrease as separation distance increase. It is concluded that the array configuration and the mergedness of the flame are the most important factors governing multi-droplet combustion.

• 한국화재소방학회논문지
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• 제27권5호
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• pp.38-43
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• 2013

보일러실이나 세탁소, 또는 음식점과 다중이용업소의 주방에 주로 설치하는 자동확산소화장치는 화재발생 시 화염이나 열에 의해 자동으로 약제가 방출되어 화재를 진압하는 소화기구 중 하나이다. 이 소화장치는 공칭방호면적에 해당하는 소화능력을 가지고 있으므로 방호대상물이 이 범위를 벗어나 있으면 유효한 화재진압이 보장되지 않지만 현행 기준에는 바닥면적에 따른 설치갯수만 요구하고 있다. 따라서 방호대상물과의 이격거리에 따라 소화성능은 달라지게 되며 이에 대한 특성을 고찰하고자 천장높이가 2.5 m인 모형화재실에 본 소화장치를 설치하고 A급, B급 모형가연물과의 수평이격거리에 따른 소화실험을 실시하였다. 실험결과 일반가연물과 유류가연물을 모두 확실하게 소화할 수 있는 최대수평이격거리는 약 30 cm인 것으로 나타났다.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2009년도 정보통신설비 학술대회
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• pp.242-247
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• 2009

In this paper, we investigate interference between short-range radiocommunication devices (SRDs) with frequency hopping spread spectrum (FHSS) and direct sequence spread spectrum (DSSS) methods when they are in the same frequency bands. In order to analyze interference from unwanted emission of SRD with DSSS to that of FHSS, Monte-Carlo (MC) simulation method is employed and interference probabilities are calculated. We simulate interference scenarios in accordance with several duty cycles and bandwidths. It is also assumed that the propagation model is free space The effect of distance between interfering transmitter and victim receiver is analyzed and bit error rate (BER) is simulated. From the interference analysis results, it is shown that duty cycle affects compatibility more than bandwidth does. Also, we can make sure of the separation distance which satisfies BER criterion when there are only one interfering transmitter and multiple interfering transmitters.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.154-155
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• 2002

The demand of the power and gas energy have been rapidly increasing with the industralization, therefore, the area where buried pipelines run parallel with the adjacent power lines and cross them increases in Seoul as well as other cities. These situation cause AC interference from the power lines. However, there aren't any standards to preserve the pipelines from AC interference in Korea. This study introduces the separation distance to protection of buried pipeline from arc strikes caused by power line ground fault current. And this study examines and compares the arc distance through case study.

• 전기학회논문지
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• 제57권2호
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• pp.179-183
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• 2008

In case of a line-to-ground fault at transmission lines, a portion of fault current will flow into the earth through the footings of the faulted tower causing electrical potential rise nearby the faulted tower footings. In this situation, any buried pipelines or structures nearby the faulted tower can be exposed to the electrical stress by earth potential rise. Although many research works has been conducted on this phenomena, there has been no clear answer of the required separation distance between tower footings and neary buried pipeline because of its dependancy on the soil electrical charactersics of the concerned area and the faulted system. In this paper, an analytical formula to calculate the requried sepeartion distance from the faulted tower has been derived.

• 아동학회지
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• 제27권1호
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• pp.95-111
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• 2006

In this study of acculturation strategies and adjustment in Korean-Chinese and Chinese-Korean children, 273 Korean-Chinese and 207 Chinese-Korean were asked about levels of assimilation to the mainstream language and culture, ethnic identity, emotional attitude toward their schools, teachers' support, peers' support, and social distance from the mainstream. Results revealed that separation was the most preferred strategy followed by integration, assimilation, and marginalization for both subject groups. Children categorized by separation strategies reported highest scores in school adjustment variables and lowest scores in social distance. There were some differences between Korean-Chinese and Chinese-Korean children in cultural assimilation, ethnic identity, emotional attitude toward school, and teacher's support. These findings were explained by their immigration history and the uniqueness of each mainstream society.

• 조명전기설비학회논문지
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• 제22권3호
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• pp.27-33
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• 2008

This paper deals with the assessment of potential interference between individual grounding electrodes using an Electrolytic Tank Modeling method. When a test current was passed through a grounding electrode, potential rise was measured and analyzed using an electrolytic tank in real time. In order to analyze the potential interference between grounding electrodes, a reduced scale modeling method was studied. Potential interference between isolated grounding electrodes was evaluated as a function of the separation distance between grounding electrodes and the configuration of grounding electrode to be induced. It was found that the separation distance between grounding electrodes was a major factor in reducing the potential interference.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
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• pp.212-213
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• 2007

In case of a line-to-ground fault at transmission lines, a portion of fault current will flow into the earth through the footings of the faulted tower causing electrical potential rise nearby the faulted tower footings. In this situation, any buried pipelines or structures nearby the faulted tower can be exposed to the electrical stress by earth potential rise. Although many research works has been conducted on this phenomena, there has been no clear answer of the required separation distance between tower footings and neary buried pipeline because of its dependancy on the soil electrical charactersics of the concerned area and the faulted system. In this paper, an analytical formula to calculate the requried sepeartion distance from the faulted tower has been derived.

• 한국산학기술학회논문지
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• 제7권3호
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• pp.265-270
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• 2006

복합재로 된 판재에 대하여 동적 균열이 접합면을 따라서 진행되어 가면서 찢어져 나갈 때 그 계면 주위에서의 응력 상태 및 변형, 견인응력 등을 조사하였다. 최대의 등가응력 및 소성 변형율은 접촉이 바로 떨어지는 부분에서 그리고 판 끝부분의 휘어지는 부근에서 최대의 변형량이 되었다. 견인력은 0.015mm정도로 그 면이 떨어졌을 때 최대치 75 MPa로서 되었다가 서서히 낮아지면서 0.13mm이상 떨어졌을 때는 0으로 일정하게 되었다. 이러한 연구 자료로서 정확한 파괴강도 해석과 안전설계 및 새로운 고급재료의 개발에 필요한 자료를 제공할 수 있는 기초적인 연구를 수행함이 본 연구의 목적이다.