• Title/Summary/Keyword: Joule effect

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Breakdown Characteristics for Insulation Design of HTS Transformer in Liquid Nitrogen

  • J.M. Joung;S.M. Baek;Kim, S.H.
    • Progress in Superconductivity and Cryogenics
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    • v.5 no.3
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    • pp.38-42
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    • 2003
  • HTS transformer is promising one of HTS power applications to be commercialized in the near future. To realize the applications, insulation technology in the coolant, liquid nitrogen, should be established. So breakdown characteristics should be considered at insulation components; turn-to-turn, layer-to-layer, winding-to-winding, were investigated. Firstly breakdown strengths of Kapton films were compared with Kraft paper these are as turn insulator. And next the characteristics of surface flashover on FRP were measured and the influence on breakdown strength of bubble generated with joule heat was discussed with the shape of cooling channel between layers. Finally barrier effect at winding-to-winding was discussed.

Degradation characteristics of ITO thin film deposited by RF magnetron sputter (RF 마그네트론 스퍼터로 증착시킨 ITO 박막의 열화 특성에 관한 연구)

  • 김용남;박정현;신현규;송준광;이희수
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2003.11a
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    • pp.234-234
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    • 2003
  • Indium tin oxide(ITO) is an advanced ceramic material with many electronic and optical applications due to its high electrical conductivity and transparency to light ITO thin films are used in transparent electrodes for display devices, transparent coatings for solar energy heat mirrors and windows films in n-p heterojunction solar cells, etc. Almost all display devices were fabricated on transparent ITO electrode substrates. There are several factors that cause decay in the efficiency and the failure of display devices. The degradation or damage of ITO is one of the main factors. Under normal operating conditions, the electric fold required for the operation of display devices is very high As a high electric field induces the joule heat, the degradation of the ITO thin film may be expected. Therefore, it is worthy to investigate the thermal and electrical effect on ITO thin films.

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Calculation of Resistance of Squirrel Cage Induction Motor End Ring using 3-D Finite Element Method (3차원 유한요소법을 이용한 농형유도전동기 단락환의 저항계산)

  • 박민우;이복용;이기석
    • The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.10 no.2
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    • pp.71-77
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    • 1996
  • The end-ring may contribute a significant influence to the performance of machine. The induced currents flow through the bars of a cage rotor and complete their closed paths by passing around the end-ring. This dissertation is to describe a method for calculating end-ring resistance of squirrel cage rotor, based on 3-D finite element method(A-$\Phi$). The resistance under consideration of skin effect is calculated by using Joule's loss equation.

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Studies on Copper Pillar Bump with Trapezoidal Cross Section on the Top Surface for Reliability Improvement (사다리꼴 상부 단면을 갖는 구리기둥 범프의 신뢰성 향상에 대한 연구)

  • Cho, Il-Hwan
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.7
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    • pp.496-499
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    • 2012
  • Modified structure of copper pillar bump which has trapezoidal cross section on the top region is suggested with simulation results and concept of fabrication process. Due to the large surface area of joint region between bump and solder in suggested structure, electro-migration effect can be reduced. Reduction of electro-migration is related with current density and joule heating in bump and investigated with finite element methods with variation of dimensional parameters. Mechanical characteristics are also investigated with comparing modified copper pillar bump and conventional copper pillar bump.

Evaluation System of the Thermal Properties of the Exothermic & Insulating Materials (발열 보온재의 특성평가 시스템 구축)

  • Shin, D.Y.;Kim, D.J.;Jun, B.H.;You, B.D.;Kim, N.S.;Oh, S.H.
    • Transactions of Materials Processing
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    • v.17 no.5
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    • pp.356-363
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    • 2008
  • An evaluation system of the thermal properties of exothermic & insulating materials was developed. By measuring the power supply of the induction furnace, the thermal property of exothermic & insulating materials could be evaluated with high reproducibility at elevated temperature of molten steel. The thermal properties of exothermic & insulating materials were affected by mixing condition of raw materials. The effect of main components of exothermic & insulating materials such as metallic aluminum and $Fe_2O_3$ powder on the exothermic and insulating properties was examined. It could be expected to design and develop various exothermic & insulating materials by means of the evaluation system of the thermal properties.

Parametric Study and Optimized Thermal Design of a High-Voltage Vacuum Circuit Breaker (고압진공차단기의 정격전류상승을 위한 GAE해석)

  • Ahn, Heui-Sub;Lee, Jong-Chul;Choi, Jong-Ung;Oh, Il-Sung
    • Proceedings of the KIEE Conference
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    • 2002.11d
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    • pp.39-42
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    • 2002
  • In this study, the computational heat transfer of the high-voltage vacuum circuit breaker was investigated. Higher normal current-ratings and stabilized thermal characteristics become more important in existing circuit breakers in order to satisfy market needs. Increases in current-ratings have an even greater effect on the Joule heating in the main circuit of the breakers. The thermal design must account for this increase in heat produced for the breaker to meet various temperature-rise limits set by industry standards. We are studying to enhance the normal current-ratings without major frame change of our present production models. As the method used in this research, we performed the computational analysis using the commercial Package, ICEPAK. We could get optimized thermal design suitable for 25% upgraded normal current-ratings through parametric study.

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A study of the effect of the temperature on the As Te Ge Si amorphous semiconductor (As Te Ge Si 무정형 반도체의 온도영향)

  • 박창엽
    • 전기의세계
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    • v.23 no.6
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    • pp.49-55
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    • 1974
  • Amorphous semiconductor from As 30 Te 48 Ge 10 Si 12 was prepared, and studied electron microscopy, X-ray analysis and resistivity measurement. It's resistivity is 1.56*10$^{6}$ .ohm.-cm when small ampule is used for preparing sample it is found that no phase separation has occurced by electron microscopy, and that phase transition temperature is 232.deg. C by differential Thermal Analysis. The specimen showed threshold switching that the low resistance state occur at critical electric field and the resistance recover at low applied field. Critical electric field of the switching is 10$^{5}$ V/cm at room temperature. Threshold voltage secreace exponentially with increasing ambient temperature and at that each voltage resistance of the switching device increase exponentially. According to the series resistance and applied vottage current slope on the V-I curve is varied. When applied voltage is decreased after switching, the resistance of the switching device is increased. By this result the origin of the switching is the Joule's heating.

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Calculation of Resistance of Cage Rotor End Ring using 3-D Finite Element Method (3차원 유한요소법을 이용한 농형유도전동기 단락환의 저항계산)

  • Bak, Min-Woo;Lee, Bok-Yong;Jung, Hae-Duk;Lee, Ki-Sik
    • Proceedings of the KIEE Conference
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    • 1995.07a
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    • pp.92-94
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    • 1995
  • This paper is to describe a method for calculating resistance of cage rotor end-ring, based on 3-D finite element method using magnetic vector potential $\vec{A}$ and electric scalar potential ${\phi}$. The induced current of a cage rotor flows through the bars of a cage rotor. The current completes their closed paths by passing around the end-ring. The end-ring may contribute a significant influence to the performance of machine. The resistance under consideration of skin effect is calculate by using Joule's loss equation.

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Analysis of the Magnetic Effect on the Tube Infrastructure for a Super Speed Tube Train

  • Lee, Hyung-Woo;Cho, Su-Yeon;Cho, Woo-Yeon;Lee, Ju;Kwon, Hyeok-Bin
    • International Journal of Railway
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    • v.2 no.4
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    • pp.170-174
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    • 2009
  • Super speed tube train is introduced to increase the speed of ground transportation. The super speed tube train levitates magnetically and runs in a partial vacuum tube, which can reduce the air resistance significantly. However, the strong magnetic force enough to propel the massive train can affect to the tube infrastructure. In this paper, authors have analyzed the leakage flux patterns and induced eddy current on the tube by using 3-dimensional Finite Element Method. These effects are investigated, especially by varying the materials and diameters of the tube. From the simulation results, the aluminum tube with the diameter of 3[m] is needed to be concerned because the induced eddy current produces joule heat, raises the inside temperature of the tube, and might be able to lead to electro-chemical corrosion on the tube, consequently reduce the durability.

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Numerical Analysis of CO2-Based Rapid Mold Cooling Technology (CO2 기반 금형 급속 냉각기술의 수치해석적 연구 )

  • Jae Hyuk Choi
    • Design & Manufacturing
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    • v.17 no.3
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    • pp.61-66
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    • 2023
  • In this study, we developed a simulation methodology for a technology that rapidly cools molds by directly spraying them with CO2 in its liquefied gaseous state. Initially, a simulation verification process was conducted using ANSYS Fluent's heat transfer analysis based on temperature values measured in prior research experiments, ensuring a comparable temperature could be calculated. Subsequently, the validated analysis method was employed to evaluate design factors that exert the most significant influence on cooling. An evaluation was conducted based on three factors: part thickness, mold thickness, and the melting temperature of material. Using a full factorial design approach, a total of 27 analyses were completed and subsequently calculated through analysis of means. The impact assessment was carried out based on the temperature values at the product's core. The results indicated that the thickness of the mold had the highest influence, while the melting temperature of material had the least.