• Journal of the Korean Society for Heat Treatment
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• v.13 no.3
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• pp.196-202
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• 2000

• Journal of the Korean Society for Nondestructive Testing
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• v.6 no.2
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• pp.7-16
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• 1987

Eddy Current Examination is expected as the effective technique for nondestructive inspection of steam generator and various kinds of heat exchanging tubes made of STS - 304. In Case of E. C. T, a study on the various factors which have an effect on coil impedance is very important to the sensitivity of defect detection and the ratio of signal to noise. Therefore, this study analyzed coil impedance by means of the variational principle, the minimized theory of energy functional and the application of Finite Element Method. Really by using E. C. T, the relationship between the size of defects and the intensity of Eddy Current Signals can be obtained. Signal intensity becomes maximum at certain frequency. This frequency is affected by the characteristics and the position of signal sources.

• Transactions on Electrical and Electronic Materials
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• v.18 no.2
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• pp.59-61
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• 2017

This research was analyzed thermal characteristics that was appointed disadvantage when smart LED driver ICs was packaged and we applied extracted thermal characteristics for optimal layout design. We confirmed reliability of smart LED driver ICs package without additional heat sink. If the package is not heat sink, we are possible to minimize package. For extracting thermal loss due to overshoot current, we increased driver current by two and three times. As a result of experiment, we obtained 22 mW and 49.5 mW thermal loss. And we obtained optimal data of 350 mA driver current. It is important to distance between power MOSFET and driver ICs. If the distance was increased, the temperature of package was decreased. And so we obtained optimal data of 3.7 mm distance between power MOSFET and driver ICs. Finally, we fabricated real package and we analyzed the electrical characteristics. We obtained constant 35 V output voltage and 80% efficiency.

• Journal of Electrical Engineering and Technology
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• v.2 no.3
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• pp.366-372
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• 2007

Joining thin aluminum alloy is difficult using most welding techniques. Many of the problems are associated with bum-through by the high heat input. Common welding techniques are TIG (Tungsten Inert Gas), MIG (Metal Inert Gas), and PULSE-MIG welding. The method provides more control of the heat balance in the welding arc by taking advantage of the different arc characteristics obtained with each of the two polarities. In this paper, we proposed a new welding method by control DSP 320C32, and the characteristic and experiment result-voltage, current, welding bead, and penetrations by this method are presented.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.7
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• pp.948-954
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• 2004

Induction heating is a process that is accompanied with magnetic and thermal situation. When the high-frequency current flows in the coil, induced eddy current generates heat to conductor. To simulate an induction and induction heating process, the finite element analysis program was developed. A coupling method between the magnetic and thermal routines was developed. In the process of magnetic analysis and thermal analysis, magnetic material properties and thermal material properties depending on temperature are taken into consideration. In this paper, to predict the angular deformation, temperature difference and the shape of heat affected zone were discussed. Also appropriate coil shape and other process variables for maximum angular deformation were proposed.

• Progress in Superconductivity and Cryogenics
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• v.2 no.2
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• pp.11-14
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• 2000

We fabricated a resistive superconducting fault current limiter (SFCL) of meander type based on a YBCO film. In order to disperse the heat generated at hot spots in the YBCO film the film was coated with a gold shunt layer. When diodes were inserted in the parallel circuit to restrict the temperature increase in the SFCL element by reducing power supply cycles, the voltage could be increased to $\sqrt{2}$ times with the same quench resistance at a half and full cycles.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.2
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• pp.120-129
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• 1994

A numerical investigation has been carried out for the electrochemical reaction, mass and heat transfer characteristics of the Molten Carbonate Fuel Cell(MCFC) stack. The effects of cooling air channel and water gas shift reaction were taken into account. The current density distribution of electrodes, the molecular fractions of reactant gasses and three dimensional temperature distribution can be calculated and shown by several lines of equivalent values. The results have been compared with the existing ones, and reasonable agreement has been obtained. To examine the influence of changing parameters, such as the composition of reactant gases, the target average current density, the utilization of reactant gases, the cooling air inlet temperature and flow rates, the computer simulation has been done. The analysis method and computer program developed in this study will be greatly helpful to design and verify the optimum operating condition of MCFC stack.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.376-378
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• 1999

In order to design the current carrying conductor for GIS, it is important to predict temperature-rise when rated current flows. This paper deals with the coupling of Flux2D and analytic method to calculate the heat transfer coefficient. Heat transfer by conduction and convection is considered between the current carrying conductor and $SF_6$ gas. The result shows reasonable temperature distribution.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.12 no.1
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• pp.78-84
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• 2016

The FHX (Forced-draft sodium-to-air Heat Exchanger) employed in the ADHRS (active decay heat removal system) is a shell-and-tube type counter-current flow heat exchanger with M-shape finned-tube arrangement. Liquid sodium flows inside the heat transfer tubes and atmospheric air flows over the finned tubes. The unit is placed in the upper region of the reactor building and has function of dumping the system heat load into the final heat sink, i.e., the atmosphere. Heat is transmitted from the primary cold sodium pool into the ADHRS sodium loop via DHX (decay heat exchanger), and a direct heat exchange occurs between the tube-side sodium and the shell-side air through the FHX tube wall. This paper describes the DHRS and the structural design of the FHX.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.202-205
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• 1995

Developed controller is the part of deflection yoke winding machine which controls the power to form the deflection yoke coil into desired shape after winding. So as to form the deflection yoke coil, it is needed to melt the bonding material which is spreaded on the coil. The heat melt the bonding material which is produced by flowing the current through the winded coil. Therefore, at first it is needed to peel off the enamel from the winded coil so as to flow the current, and then supply the power to produce the heat which form the winded coil into desired shape. Naturally developed controller is composed of the peeling part and the conduction and forming part. All of them consist of the inverter structure and control the output current. The peeling is achieved by low voltage and high AC current, the conduction and forming is by DC current. Developed controller also has a function that detect the resistance of the deflection yoke coil to prevent the damage of the load which is produced by poor peeling.