• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.327.2-327
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• 2002

In this paper, the transmitted noise reduction of smart panels of which passive piezoelectric shunt damping is used, is experimentally studied. Shunt damping experiments are based on the measured electrical impedance model. A passive shunt circuit composed of inductor, and load resistor is devised to dissipate the maximum energy into the joule heat energy For multi mode shunt damping, the shunt circuit is redesigned by adding a blocking circuit. (omitted)

• Progress in Superconductivity and Cryogenics
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• v.4 no.2
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• pp.27-30
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• 2002

One dimensional conduction equation is solved by finite difference method, to analyse the stability of Au/YBCO film deposited on a sapphire substrate. Joule heat is included in the case of current sharing state. The analysis shows the quench and recovery of superconductor depending on the amount of thermal disturbance release on the center surface of superconductor. The critical disturbance energies for different filling factor and operating current are calculated.

• The Journal of the Acoustical Society of Korea
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• v.37 no.5
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• pp.317-322
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• 2018

It has been generally known that a hole presenting on the center of pole piece for the loudspeaker can be very helpful for the heat, which is radiated by Joule Effect at the voice coil, to emit to the outside of the magnetic gap. The existence of hole can also become a cause of the changes of the acoustical properties about the loudspeaker. The resonance frequency of loudspeaker increased with the increase of hole radius. However, increasing the hole length resulted in the decrease of the resonance frequency. These results are in an excellent agreement with the theoretical predictions for the equivalent mechanical circuit of Bass-Reflex cabinet system. The acoustical property of the loudspeaker with hole can be also predicted by the theoretical interpretation of Bass-Reflex cabinet system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.9
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• pp.69-74
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• 2008

The frost and freezing on contact wire in winter is a very serious problem Shocks at the mechanical interface of the collecting strips of the pantograph and the contact wire. Extra electrical resistance, which may affect quality of current collection at the contact wire / collecting strips of pantograph interface. De-icing system is to melt frost or freezing in contact wire. The principle of do-icing system is to melt frost or ice by Joule heat of contact wire impedance. The temperature of the contact wire was increased with increasing the current. But temperature of contact wire was decreased with increasing the velocity of the wind.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.6
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• pp.409-414
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• 2017

The aim of this study is to understand the phonon transfer characteristics of a silicon thin film transistor. For this purpose, the Joule heating mechanism was considered through the electron-phonon interaction model whose validation has been done. The phonon transport characteristics were investigated in terms of phonon mean free path for the variations in the device power and silicon layer thickness from 41 nm to 177 nm. The results may be used for developing the thermal design strategy for achieving reliability and efficiency of the silicon-on-insulator (SOI) transistor, further, they will increase the understanding of heat conduction in SOI systems, which are very important in the semiconductor industry and the nano-fabrication technology.

• Korean Journal of Materials Research
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• v.9 no.11
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• pp.1112-1116
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• 1999

Thermoelectric effects on the temperature changes at the solid- and liquid-phase and its interface were studied by using the unidirectional solidification of $\textrm{Bi}_{2}\textrm{Te}_{3}$. Cooling or heating effects measured with current density. polarity and current passing time were quite different. By separating sole Peltier, Thomson and Joule heat theoretically and experimentally, the Peltier coefficient at the solid/liquid interface of $\textrm{Bi}_{2}\textrm{Te}_{3}$ was -1.10$\times\textrm{10}^{-1}$V, and the Thomson coefficients of solid- and liquid-phase were 7.31\times\textrm{10}^{-4}V/K, 5.77\times\textrm{10}^{-5}V/K, respectively. When D.C. passed from solid-phase to liquid-phase during the crystal growth of $\textrm{Bi}_{2}\textrm{Te}_{3}$ the crystal with more directionality was obtained owing to increase of the temperature gradient in liquid by the Peltier cooling. But in reverse current direction, the crystallinity was not changed significantly.

• Tribology and Lubricants
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• v.29 no.5
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• pp.318-323
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• 2013

Overheating in electrical motors results in detrimental effects such as degradation of the insulation materials, demagnetization of magnets, increases in Joule losses, and decreases in motor efficiency and lifetime. Thus, it is important to find ways to dissipate heat from the motor and to keep the motor operating at its most efficient temperature. In this study, a new design to guide air flow through a given brushless direct current (BLDC) motor is developed and the design is analyzed, specifically by using computational fluid dynamics (CFD) simulations. The results showed that the temperature distribution in the three proposed models is lower than that in the original model, although the speed of the cooling fan in the original model reaches a very high value of $15{\times}10^3$ rpm. The results also showed that CFD can be effectively used to simulate the heat transfer of BLDC motors.

• 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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.7
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• pp.931-936
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• 2013

In this paper, the temperature distribution of 400kVA hybrid transformer is predicted by using CFD analysis. The copper loss and iron loss which are heat source are calculated by using Joule heat and Bertotti's equation respectively. To improve the convergence of the numerical calculation and to reduce the computation time, the 1/4 model is used and the incompressible air model is used for external air. To verify analysis result, the temperature rise test and no-load test of the transformer are performed. The experiment result obtained by using thermo-graphic camera is similar to the numerical result of the CFD analysis.

• 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.