• Title, Summary, Keyword: Hot spot

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A Design Technique of Homogenous Hot Spot for Object-Oriented Components (객체지향 컴포넌트 개발을 위한 동질 Hot Spot 설계 기법)

  • 박동혁;김수동
    • Proceedings of the Korean Information Science Society Conference
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    • pp.444-446
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    • 1999
  • 컴포넌트 기반의 개발과 컴포넌트 개발에 대한 관심이 높아지면서 이를 위한 개발 방법론과 개발 도구들의 도입이 확산되고 있다. 또한 컴포넌트의 재사용 범위를 확장시키기 위해 컴포넌트 개발 시 나타나는 Hot Spot 처리를 위한 분석, 설계기법에 대한 관심이 높아지고 있다. 따라서 본 논문에서는 Hot Spot 처리시에 나타나는 의존적인 Hot Spot을 디자인하는 방법을 제시하고 그 방법을 적용하여 의존적인 Hot Spot을 디자인 할 때 발생되는 Hot Spot 간의 결합도 줄이고 디자인 모델의 가독성을 높인다. 본 논문에서는 디자인 모델링을 위한 표기법으로서 객체지향 모델링 기법인 (UML(Unified Modeling Language)를 이용하여 모델링한다.

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A Study on the Hot Spot Temperature in 154kV Power Transformers

  • Kweon, Dong-Jin;Koo, Kyo-Sun;Woo, Jung-Wook;Kwak, Joo-Sik
    • Journal of Electrical Engineering and Technology
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    • v.7 no.3
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    • pp.312-319
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    • 2012
  • The life of a power transformer is dependent on the life of the cellulose paper, which influenced by the hot spot temperature. Thus, the determination of the cellulose paper's life requires identifying the hot spot temperature of the transformer. Currently, however, the power transformer uses a heat run test is used in the factory test to measure top liquid temperature rise and average winding temperature rise, which is specified in its specification. The hot spot temperature is calculated by the winding resistance detected during the heat run test. This paper measures the hot spot temperature in the single-phase, 154kV, 15/20MVA power transformer by the optical fiber sensors and compares the value with the hot spot temperature calculated by the conventional heat run test in the factory test. To measure the hot spot temperature, ten optical fiber sensors were installed on both the high and low voltage winding; and the temperature distribution during the heat run test, three thermocouples were installed. The hot spot temperature shown in the heat run test was $92.6^{\circ}C$ on the low voltage winding. However, the hot spot temperature as measured by the optical fiber sensor appeared between turn 2 and turn 3 on the upper side of the low voltage winding, recording $105.9^{\circ}C$. The hot spot temperature of the low voltage winding as measured by the optical fiber sensor was $13.3^{\circ}C$ higher than the hot spot temperature calculated by the heat run test. Therefore, the hot spot factor (H) in IEC 60076-2 appeared to be 2.0.

The Origin and Effect of Hot Spot Phenomena on Judder Vibration in Automotive Disk Brake (디스크 브레이크에서 열섬 현상이 발생되는 원인과 저더 진동에 미치는 영향)

  • Cho, Ho-Joon;Cho, Chong-Du;Kim, Myoung-Gu;Maeng, Ju-Won;Lee, Jae-Han
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.213-218
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    • 2006
  • Hot spot phenomenon is caused by non-uniform contact area between brake pad and disk frequent braking. Brake disk deformed by locally concentrated heat increases magnitude of frictional vibration. And this deformation can highly influence the judder vibration. In this experimental study, vibration and hot spot was measured in accordance with rotation of disk and pressure of master cylinder for finding the factors that causes hot spot phenomena. For comparing hot spot aspects with mode shapes of disk, mode shapes were measured by conducting modal test, and analyzed by using finite element analysis. Relation between hot spot phenomenon, and mode shape, pressure of master cylinder and rotation speed of disk respectively, was achieved by hot spot measurement and frequency analysis.

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The Origin and Effect of Hot Spot Phenomena on Judder Vibration in Automotive Disk Brake (디스코 브레이크에서 열섬 현상이 발생되는 원인과 저더진동에 미치는 영향)

  • Cho, Chong-Du;Kim, Myoung-Gu;Cho, Ho-Joon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.8
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    • pp.886-892
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    • 2006
  • Hot spot phenomenon is caused by non-uniform contact area between brake pad and disk frequent braking. Brake disk deformed by locally concentrated heat increases magnitude of frictional vibration. And this deformation can highly influence the judder vibration. In this experimental study, vibration and hot spot was measured in accordance with rotation of disk and pressure of master cylinder for finding the factors that causes hot spot phenomena. For comparing hot spot aspects with mode shapes of disk, mode shapes were measured by conducting modal test, and analyzed by using finite element analysis. Relation between hot spot phenomenon, and mode shape, pressure of master cylinder and rotation speed of disk respectively, was achieved by hot spot measurement and frequency analysis.

The effect of I-V characteristic and hot-spot by solar cell and interconnection circuit in PV module (PV모듈에서 태양전지와 Interconnect회로의 구성이 I-V특성과 Hot Spot에 미치는 영향)

  • Lee, Jin-Seob;Kang, Gi-Hwan;Park, Chi-Hong;Yu, Gwon-Jong;Ahn, Hyung-Gun;Han, Deuk-Young
    • 한국태양에너지학회:학술대회논문집
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    • pp.241-246
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    • 2008
  • In this paper, we analyze the I-V curve and hot-spot phenomenon caused by solar cells' serial and parallel connected circuit. The mis-match loss of parallel interconnection with low Isc string decrease lower than serially interconnected one and temperature caused by hot-spot does. Also, mis-match loss of parallel interconnection with low Voc string increase more than serially interconnected one. The string having low Voc happened hot-spot phenomenon when open circuit. The bad solar cell in string gives revere bias to good solar cell and make hot-spot phenomenon. If we consider the mis-match loss, when designing PV module and array. the efficiency of PV system might increase.

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Design of Edge Type LED Backlight System for reduce Hot spot (Hot spot 감소를 위한 Edge Type LED Backlight 설계)

  • Kim, Yong-Suk;Lim, Sung-Kyoo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.551-554
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    • 2004
  • LED는 소비전력이 적고, 수명이 길어 LCD Backlight 용 광원으로 주목받고 있다. 현재 휴대전화기용 LCD에 많이 사용되고 있는 소형 LED Backlight의 경우 입광부에 LED의 개수가 육안으로 확인 가능할 정도의 Hot Spot이 존재한다. 이에 본 논문에서는 Reflector를 사용하여 광의 손실을 줄이고 도광판의 입광부에 산란 패턴을 설계하여 적용함으로써 도광판 입광부에서 122.7%의 휘도 상승효과와 73.4%의 휘도 균일도를 얻을 수 있었으며 이로 인해 Hot Spot을 감소시킬 수 있었다.

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A Study of Frictional Contact Vibration Influence on Hot Spot in Automotive Disk Brake (디스크 브레이크에서 접촉 마찰 진동이 열섬에 미치는 영향 연구)

  • Cho, Ho-Joon;Kim, Myoung-Gu;Cho, Chong-Du
    • Transactions of the Korean Society of Automotive Engineers
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    • v.15 no.1
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    • pp.154-161
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    • 2007
  • Hot spot phenomenon that occurs, during judder vibration, is locally concentrated heat due to friction between brake disk and pad. It is important to understand the reason behind hot spot phenomenon, for reduction of judder vibration. In this experimental study, experiments were performed in accordance with rotation speed of brake disk, pressure of master cylinder and pad length for achieving different aspects of hot spot phenomenon. Temperature distribution of hot spot was obtained by using the infrared camera. As the hot spot occurred, vibration was measured and frequency analysis was performed. Finite element analysis of thermal deformation of disk was performed by using temperature distribution that was achieved by experimental results. And mode shapes of disk was analyzed by finite element analysis and compared with experimental results. It was observed that the excitation frequency band of frictional contact and frictional force mainly affects the hot spot phenomenon.

Hot spot stress approach for Tsing Ma Bridge fatigue evaluation under traffic using finite element method

  • Chan, T.H.T.;Zhou, T.Q.;Li, Z.X.;Guo, L.
    • Structural Engineering and Mechanics
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    • v.19 no.3
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    • pp.261-279
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    • 2005
  • The hot spot stress approach is usually adopted in the fatigue design and analysis of tubular welded joints. To apply the hot spot stress approach for fatigue evaluation of long span suspension bridges, the FEM is used to determine the hot spot stress of critical fatigue location. Using the local finite element models of the Tsing Ma Bridge, typical joints are developed and the stress concentration factors are determined. As a case for study, the calculated stress concentration factor is combined with the nominal representative stress block cycle to obtain the representative hot spot stress range cycle block under traffic loading from online health monitoring system. A comparison is made between the nominal stress approach and the hot spot stress approach for fatigue life evaluation of the Tsing Ma Bridge. The comparison result shows that the nominal stress approach cannot consider the most critical stress of the fatigue damage location and the hot spot stress approach is more appropriate for fatigue evaluation.

Winding Temperature Measurement in a 154 kV Transformer Filled with Natural Ester Fluid

  • Kweon, Dongjin;Koo, Kyosun
    • Journal of Electrical Engineering and Technology
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    • v.8 no.1
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    • pp.156-162
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    • 2013
  • This paper measures the hot spot temperatures in a single-phase, 154 kV, 15/20 MVA power transformer filled with natural ester fluid using optical fiber sensors and compares them with those calculated by conventional heat run tests. A total of 14 optical fiber sensors were installed on the high-voltage and low-voltage windings to measure the hot spot temperatures. In addition, three thermocouples were installed in the transformer to measure the temperature distribution during the heat run tests. In the low-voltage winding, the hot spot temperature was $108.4^{\circ}C$, calculated by the conventional heat run test. However, the hot spot temperature measured using the optical fiber sensor was $129.4^{\circ}C$ between turns 2 and 3 on the upper side of the low-voltage winding. Therefore, the hot spot temperature of the low-voltage winding measured using the optical fiber sensor was $21.0^{\circ}C$ higher than that calculated by the conventional heat run test.