• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1265-1270
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• 2008

Electromigration is a one of a critical failure mechanism in microelectronic devices. Minimizing the thin film interconnections in microelectronic devices make high current densities at electrrical line. Under high current densities, an electromigration becomes critical problems in a microelectronic device. This phenomena under DC conditions was investigated with high temperature. The current density of 1.5MA/cm2 was stressed in interconnections under DC condition, and temperature condition $150^{\circ}C,\;175^{\circ}C,\;200^{\circ}C$. By increasing of thin film interconections, microelectronic devices durability is decreased and it gets more restriction by temperature. Electromigration makes electronic open by void induced, and hillock induced makes electronic short state.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.26-28
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• 2007

This research is concerned with a study of failure strength evaluation on heat element gap at resistance welding. The failure strength of resistance welded joint is changed by welding factor like as current(power level), welding time(total energy), pressure etc. and another heat element factor like as number of element line, element gap etc. Tensile-shear tests were carried out with the single-lap specimen using polypropylene(PP). The failure mechanism and optimization of gap was discussed in order to explain the tensile-shear strength evaluation on heat element gap at resistance welding. Orthogonal array was used by fractional factorial design for efficient experiments.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.402-405
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• 2006

The diffuser noise of HVAC(heating ventilating and air-conditioning) uses dB(A) or NC as a indoor noise criteria that ASHRAE represents, and there is no specific guide line for application. According to the previous study, there are some problems like that even though the sound level of sound source is same, the NC shows different values, which makes the noise rating confused. This problem is caused by the frequency characteristics of sound source and its sound level. Therefore, appropriate evaluation method should be considered based on the subjective responses. This study aims to analyze the physical parameters appropriate for the evaluation of HVAC diffuser noise. To achieve this, recording of sound sources, calculation of physical parameters and psycho-acoustic experiment were carried out and the results were derived from the correlation analysis between physical parameters and subjective evaluatio

• Journal of the Mineralogical Society of Korea
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• v.2 no.1
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• pp.1-7
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• 1989

The terrestrial Ca-buserite has been found from Dongnam mine, Korea. It occurs in close association with rancieite in the manganese oxide ores which were formed by supergene weathering of hydrothermal rhodochrosite in veins. A study on this mineral using X-ray diffraction, infrared, polarizing and electron microscopes and dehydration experiment shows that the natural cabuserite (10$\AA$ phase) is more or less unstable, transforming partly to rancieite (7.5 $\AA$ phase) in the natural environment, and upon heating, its 10 $\AA$ line shifts to 7.5$\AA$ at 70-9$0^{\circ}C$. The Ca-buserite is the hydrate of rancieite.

• Journal of Biosystems Engineering
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• v.22 no.1
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• pp.59-67
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• 1997

An experimental apparatus was developed for the rapid determination of thermal conductivity by transient probe method. The theoretical basis for transient probe method has been investigated. The mathematical model for this method is the Carslaw and Jaeger model which is used perfect line source theory. The small needle probe which is equipped with thermocouple and heating element is constructed. A software that performs data analysis and acquisition is programmed. The influence of the power dissipated per unit length of the probe has been assessed for glycerin. The result showed no significant correlation between thermal conductivity and power input. Determination made with this experimental apparatus were found to agree well with the recommended thermal conductivity data.

• Journal of the Korea Furniture Society
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• v.13 no.1
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• pp.27-37
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• 2002

This study was investigated with the surface properties such as physical and accelerated tests of wood-based floorings. In physical test, hardness and abrasion resistance values of laminate floorings were higher than those of others. The center line average surface roughness($R_a$) of imported laminate flooring was highest value($1.34{\mu}m$) and that of imported solid wood flooring was lowest value($0.62{\mu}m$). In cold resistance and moist heat resistance, no defects were found on the surface of all flooring (crack, blistering, peeling, and gloss loss etc.) after testing. Wet-cold-dry cycle test showed that plywood flooring appeared some cracks. In accelerated weathering test, color difference increased with increasing Xenon arc light irradiation

• Proceedings of the Safety Management and Science Conference
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• 2010.04a
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• pp.81-95
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• 2010

Gas turbines generating power operate in high temperature condition and use natural gas as fuel. For that reason, there are many cases where damage is done to the hot gas parts caused by the high temperature and many accidents occur like gas explosions, then various efforts are needed to maintain the hot gas parts and prevent accidents. It is difficult to find the root causes of damage to the hot gas parts from the gas explosion caused by gas leakage through rotor cooling air line from fuel gas heat exchanger during the shut down. To prevent gas turbine from damage, removal of gas leakage inside of gas turbine is required by purging the turbine before firing, improving the fuel gas heating system and installing alarm systems for detecting gas leakage from stop valve to turbine while the gas turbine has shut down.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.433-444
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• 2008

Nowadays, subway station has provided not only transportation but living spaces for everyday activities. Therefore, a variety of facilities have been installed for a safety of citizens such as fire-fighting equipment, platform screen doors and giving high level of benefits such as air-conditioning and heating equipment, escalators, lighting apparatus. In order to operate these facilities appropriately, it is needless to say that electric power supply must be reliable. Many protection relays have been installed to protect electric apparatus and power system, nevertheless it..s study has been insufficient in the concrete. From this paper, through analyzing of protection relay system of electric room operated in line 2 of Seoul metro, we can help to improve stable power supply system of subway station.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.04a
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• pp.216-225
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• 1998

Although artificial neural network based on backpropagation algorithm is an excellent system simulator, it has still unsolved problems of its structure-decision and learning method. That is, we cannot find a general approach to decide the structure of the neural network and cannot train it satisfactorily because of the local optimum point which it frequently falls into. In addition, although there are many successful applications using backpropagation learning algorithm, there are few efforts to improve the learning algorithm itself. In this study, we suggest a general way to construct the hidden layer of the neural network using binary genetic algorithm and also propose the various learning methods by which the global minimum value of the teaming error can be obtained. A XOR problem and line heating problems are investigated as examples.

• Bulletin of the Society of Naval Architects of Korea
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• v.13 no.1
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• pp.25-34
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• 1976

Analytical solutions for the transient temperature and quasi-static thermal stresses which arise in thin plates subjected to an instantaneous point source of heat have been investigated. And the solutions have been extended to the case of a moving source of heat with the aid of the Duhamel's superposition integral. For finite disk an experiment was conducted, the measured temperature histories show a good agreement with the theoretical temperature histories, And the histories of thermal stresses show a good qualitative agreement with the physical phenomena. And also we can find out that the maximum temperature and thermal stresses and their location can be estimated by using the solutions for infinite plates instead of the solutions for a finite plate. The solutions can be used for the problems such as a welding or line heating in a hull construction.