• 제목/요약/키워드: Overheating factor

검색결과 12건 처리시간 0.033초

전기폭발법에서 SMPS를 이용한 Cu 나노분말의 실시간 입자특성평가 (In-situ Particle Characterization of Cu Nanopowder using Scanning Mobility Particle Sizer in Pulsed Wire Evaporation Method)

  • 이창우;맹덕영;박중학;유지훈;이재훈;이창규;김흥회
    • 한국분말재료학회지
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    • 제10권4호
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    • pp.275-280
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    • 2003
  • Synthesis and characteristics of Cu nanopowder were considered by in-situ characterization method using SMPS in pulsed wire evaporation process. With increasing pressure in chamber, particle size and degree of agglomeration increased by increase of collision frequency. Also, it was found from the XRD analyses and BET measurements that crystallite size and particle size decreased with elevating applied voltage. However, SMPS measurements and TEM observation revealed the increase of particle size and degree of agglomeration with increase of applied voltage. These results suggested that particle growth and agglomeration depend on overheating factor in chamber at the early stage and thermal coagulation in filtering system during powder formation until collection.

사무용 빌딩에서의 전압 및 전류파형 왜곡특성 분석 (Analysis of Volatage and Current Waveform Distortion Characteristics at Office Buildings)

  • 유재근;이상익;전정채;정종욱;임용배
    • 조명전기설비학회논문지
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    • 제19권1호
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    • pp.155-161
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    • 2005
  • 사무용 빌딩의 비선형 전자부하에 기인한 전압 및 전류파형의 왜곡은 중성선의 과열, 변압기 손실, 누전차단기 오동작 등을 야기 시킨다. 본 논문에서는 사무용 빌딩에서의 전압 및 전류 고조파의 크기, 전압 및 전류 파고율(Crest Factor : CF), 전압 및 전류 불평형 등을 비교함으로써 파형왜곡 특성을 분석하였다. 분석 결과, 고조파에 의한 상 및 중성선에서의 심각한 파형 왜곡 문제와 삼상에서의 단상 부하의 부적절한 분배로 인한 전류 불평형이 심한 빌딩이 조사되었다. 본 연구 결과는 사무용 빌딩에서 합리적이고 경제적인 부하운용을 위해 사용될 수 있을 것이다.

3상4선식 계통에서 중성선 영상고조파 저감에 따른 기대효과 (The expectation effects of a decrease in neutral wires Zero Sequence harmonic currents in 3 phases - 4 wires systems)

  • 강창원;이성우;정연해;김세동;이원구
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2002년도 하계학술대회 논문집 B
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    • pp.715-719
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    • 2002
  • Recently, Dangers due to harmonics emanated from all sorts of machinery have been on the increase with the development in industry. One of them is that Zero Sequence harmonic currents flow from the neutral wires in 3 phases - 4 wire systems. The flowing of harmonic currents in neutral wires brings about the superheating and falloff in output of transformer, the overheating of them, a rise in ground potential and the wrong movement of machinery, so has a bad influence on this system. To develop the machinery to decrease neutral wires Zero sequence harmonic currents and apply it help solve these problems and bring about the effects of a improvement in power factor and energy savings.

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신개념 수동형 고조파 필터 개발과 성능에 관한 평가 (Development of a Novel Passive Harmonic Filter)

  • 박병주;이한상;장길수
    • 대한전기학회논문지:전력기술부문A
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    • 제55권1호
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    • pp.29-36
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    • 2006
  • The interest for harmonic problems has been increasing due to the increment of nonlinear loads. The loads such as DC power system, personal computers, UPS system, inverters and converters operate as harmonic current sources. In this paper, a new type of the passive filter, Hybrid Harmonic Filter (HHF) is suggested to mitigate harmonic problems in power systems. The HHF is developed for reducing harmonic current, especially on the system that includes 6-pulse bridge rectifiers. Also, it is expected to prevent the overheating of transformers and feeders due to overcurrent and to correct the power factor.

외부화재시 LPG 소형저장탱크의 안전성에 관한 연구 (A Study on the Safety of Small LPG Storage Tanks at External Fires)

  • 임지표;마병철;정창복
    • 한국안전학회지
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    • 제30권4호
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    • pp.64-72
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    • 2015
  • The purpose of this study is to study the safety of a small LPG storage tank with a capacity less than 3 ton when it is exposed to an external fire. First, simulation studies were carried out using ASPEN Plus and PHAST to demonstrate that overpressurization in the tank can be relieved by discharging the LPG through an adequately sized safety valve, but the release may lead to the secondary risk of fire and explosion around the tank. Next, the temporal variations of the temperatures of the lading and tank wall were obtained using AFFTAC, which showed that the tank wall adjacent to the vapor space could be overheated in about 11 min to such a point that the weakened strength might cause a rupture of the tank and subsequent BLEVE. The consequences of the BLEVE were estimated using PHAST. Finally, several practical measures for preventing the hazards of overheating were suggested, including an anti-explosion device, sprinkling system, insulation, heat-proof coating, and enhanced safety factor for tank fabrication. The effectiveness of these measures were examined by simulations using AFFTAC and ASPEN Plus.

전기선폭발법에 의한 Cu-Ni-P 합금 나노 분말 제조 (Cu-Ni-P Alloy Nano Powders Prepared by Electrical Wire Explosion)

  • 김원백;박제신;서창열;이재천;김정환;오용준
    • 한국분말재료학회지
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    • 제14권2호
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    • pp.108-115
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    • 2007
  • Cu-Ni-P alloy nano powders were fabricated by the electrical explosion of electroless Ni plated Cu wires. The effect of applied voltage on the explosion was examined by applying pulse voltage of 6 and 28 kV, The estimated overheating factor, K, were 1.3 for 6 kV and 2.2 for 28 kV. The powders produced with pulse voltage of 6 kV were composed of Cu-rich solid solution, Ni-rich solid solution, and $Ni_3P$ phase. While, those produced with 28 kV were complete Cu-Ni-P solid solution and small amount of $Ni_3P$ phase. The initial P content of 6.5 at.% was reduced to 2-3 at.% during explosion due to its high vapour pressure.

교실에 설치된 블라인드의 유형과 색상에 따른 실내 온열환경 평가 (Evaluation of Indoor Thermal Environment according to Type and Color of Blinds Installed in the Classroom)

  • 권대혁;이재로;오주석;위승환;김수민
    • 한국가구학회지
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    • 제28권3호
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    • pp.224-232
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    • 2017
  • Building energy saving have been put effort in a long time since buildings consume about 40.6% of total energy use, where heating, cooling and electrical lighting requirement results in energy consumption of building significantly. The window is an important part of building envelope, it usually brings a certain heat load from solar radiation while it allows light passing through, and properly leads to overheating in summer, hence the cooling load increase sand cause of thermal uncomfortable factor. The purpose of this study was to evaluate internal shade performance according to color and materials. There is growing interest in improving the sense of comfort among students who spend most of their time in the classroom. The study examined thermal environment and light environmental performance according to the color and materials of internal blinds to the school classroom. The results of this study were as follows; Among wooden blinds, aluminium blinds, and polyester blinds, the aluminium blinds were most excellent. In addition, among white blinds, light brown blinds, dark brown blinds, the light brown were most excellent.

4극 저압차단기 N상 Trip장치를 사용한 영상고조파 안전성 개선방안 (Safely Improving Method to Zero-Harmonics Current with 4-Pole Low Voltage Circuit Breaker Equipped N-phase Trip Device)

  • 기채옥;김주철;최창규
    • 한국조명전기설비학회:학술대회논문집
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    • 한국조명전기설비학회 2009년도 춘계학술대회 논문집
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    • pp.458-461
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    • 2009
  • 3상 4선식 배전방식에서 비선형 부하증가로 인한 제 3고조파 전류발생은 선로의 중성선 및 기기를 과열시키는 원인으로 작용하고 있다. 따라서 고조파에 의한 역률저하 및 기기, 선로 등을 안전하게 보호할 필요가 있다. 본 논문에서는 제 3고조파 전류로 인한 사고사례를 조사하고 고조파 분석 및 부하 불평형 등을 분석하였다. 이를 통해 가장 경제적인 4극 저압차단기를 사용하여 중성선의 과전류로부터 선로 및 기기를 보호하는 방법을 제시하였다.

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야영장 내 액화석유가스 사용실태 및 위험요소 분석 (An analysis of the Liquefied Petroleum Gas Usage and Risk Factor in the Camp Site)

  • 이덕권;이승국;이연재;김희식
    • 한국가스학회지
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    • 제20권6호
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    • pp.89-94
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    • 2016
  • 국내 캠핑문화의 확산과 국민 여가문화의 선진화에 따라 야영인구 및 야영장의 수가 급속히 증가하고 있다. 야영인구 및 야영장 수의 빠른 증가로 인하여 안전사고 또한 급격히 증가하고 있어서 효율적인 안전관리 대책이 필요하다. 특히, 과열에 의한 부탄캔의 폭발, 밀폐된 공간에서 연소기 사용에 의한 CO 중독 등의 가스사고가 증가하고 있으므로 사고를 예방하는데 집중할 필요가 있다. 본 연구에서는 취사장, 샤워장 등 야영장 시설에서 사용되는 액화석유가스 시설과 주요 캠핑용품의 사용실태 및 위험요소를 분석하고 효과적인 안전관리 방안 도출을 위한 방향을 제시하고자 하였다. 본 연구의 결과를 통해 국내 야영장 내 액화석유가스 사용 상 안전 관리 효율성 증대에 도움이 될 수 있을 것으로 기대한다.

비화재보를 위한 X-ray tube 내 열 유동해석에 관한 연구 (A study on thermal fluid analysis in X-ray tube for non-fire alarm)

  • 윤동민;전용한
    • Design & Manufacturing
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    • 제16권2호
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    • pp.33-38
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    • 2022
  • Currently, Korea is an aging society, and it is expected to enter a super-aging society in about 4 years. Accordingly, many X-ray technologies are being developed. In X-rays, 99% of X-rays are converted into heat energy and 1% into light energy (X-rays). 99% of the thermal energy raises the temperature of the anode and its surroundings, and the cooling system is an important factor as overheating can affect the deterioration of X-ray quality and shortened lifespan. There is a method of forced air cooling using natural convection. Therefore, in this study, when X-rays were taken 5 times, Flow analysis was performed on heat removal according to temperature rise and cooling time for the heat generated at the anode of the X-ray tube (input power 60kW, 75kW, 90kW). Based on one-shot, the most rapid temperature rise section increased by more than 57% to 0.03 seconds, A constant temperature rises from 0.03 seconds to 0.1 seconds, It is judged that the temperature rises by about 8.2% or more at one time. After one-shot cooling, the cooling drops sharply from about 60% to 0.03 seconds, It is judged that the temperature has cooled by more than 86% compared to the temperature before shooting. One-shot is cooled by more than 86% with cooling time after 0.1 seconds, As the input power of the anode increases, the cooling temperature gradually increases. Since the tungsten of the anode target inside the X-ray tube may be damaged by thermal shock caused by a rapid temperature rise, an improvement method for removing thermal energy is required when using a high-input power supply.