• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1213-1219
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• 2008

The deterioration analysis of electric systems in diesel electric locomotives, which were used for over 30 years, was performed to understand current wear and safety information. The electric systems include electric generation, traction motors, control units, high-voltage cables, and wires. In this investigation, various types of performance testing, such as insulation resistance measurement and degradation tests, were conducted to assess the degree of current deterioration. Moreover, an infrared camera was employed to verify abnormal heating in cables and wires. In this paper, the new techniques for evaluation of deterioration in electric systems have been introduced.

• Transactions of Materials Processing
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• v.22 no.4
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• pp.189-195
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• 2013

In this study, the weld strength of extru-rivet spot welding was investigated by simulation and experiment. In order to obtain hot plasticity flow bonding of the two plates by a single rivet, electrodes are used for heating of the two plates and the rivet by electric resistance. Because weld strength is influenced by the temperature in the weld zone, the diameter of the electrodes and the amount of current supplied to the electrodes are important variables. For the simulation, heat distribution and weld strength were calculated using DEFORM-3D. The weld strength in the weld zone was calculated for various values of the experimental parameters. The simulation results showed that the weld strength was the highest when the weld current was 37kA, the electrode diameter was 12mm, and the welding frequency was 90cycle. Aluminum 5052 was used for the experimental study. A total of three aluminum plates, two welding plates with 1mm thickness and one plate with 2mm thickness for the inserting rivet, were used for the experimental extru-rivet spot welding.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04c
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• pp.10-14
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• 2008

In this paper, abnormal heating of circuit breaker in panel board by poor connection was studied. Firstly, calculation method of contact resistance shown in IEC 60943 was examined. Secondly, concerning abnormal heating of circuit breaker in panel board, field measurements were performed. Field measurements showed that locally abnormal heating by poor connection could be detected, therefore, in that case, immediate action was needed. Finally, experiments regarding abnormal heating between terminal of circuit breaker and electric wire were conducted. The results showed that abnormal heating above $180^{\circ}C$ was measured. Also, in the results of analysis of electrical waveforms according to load current, voltage drop occurred around poor connection, and the oxide was generated according to mechanical vibration. In order to prevent electrical disaster caused by poor connection, adequate torque should be applied to electrical connection, and periodic check-ups are needed.

• Polymer(Korea)
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• v.26 no.3
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• pp.367-374
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• 2002

Electrical characteristics of crystalline polymer composites filled with nano-sized carbon black particle were studied. The developed composite system exhibited a typical positive temperature coefficient resistance (PTCR) characteristic, where the electrical resistance sharply increased at a specific temperature. The PTCR effect was sometimes followed by a negative temperature coefficient resistance (NTCR) feature with temperature, which seemingly caused by the coagulation of nano-sized carbon black particles in the excessive quantity. The PTCR temperature was controlled by the carbon black content and the external voltage. The change of electric conductivity was shown as a function of carbon black content, and the resistance was constant when the carbon black content was over 20 wt%. The room-temperature resistance was maintained by a repeated heating and cooling. The excellent PTCR characteristic was demonstrated by the low resistance in the initial stage and the instantaneous heating capability.

• Proceedings of the KWS Conference
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• 1996.05a
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• pp.13-14
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• 1996

High Frequency Electric Resistance Welding process has been widely used in manufacturing welded steel pipes because of its high welding speed and quality. This process utilizes the skin effect as well as the proximity effect of the high frequency current in heating the skelp edge. In this study, an analytical solution of the edge temperature was obtained based on several assumptions. The assumptions includes the expontial decay of weldingcurrent from the surface and neglect of the heat loss in the welding direction. This calculation shows a good agreement with the observations made from the high speed camera. Using tile analytical model, tile heat required as a function of the welding speed and the skelp thickness was determined. These results were compared with the experimental results obtained.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1433-1438
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• 2007

Characteristics of a phase change type micro actuator have been studied. The micro actuator has been designed for a micro-pump in an active direct methanol fuel cell(DMFC), consisting of an actuating chamber, a membrane, an electric heater, and a sensor of resistance temperature detector (RTD). In the present study, researches have been focused on the response of the actuator to control algorithm of the heater. The experiments demonstrated that the displacement of the membrane increase with temperature variation which is a function of applied voltage, duty ratio, and operating frequency of heating. The results also showed that operation of the actuator with high voltage at small duty of heating is more efficient than the same power consumption of heating with low voltage at large duty.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.465-473
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• 2013

In this Study, the performance of precast PSC slabs with fire resistance panel for fire resistance of the tunnel system was evaluated by experimentally. The fire test was performed in fire resistance (electric) furnace according to RABT(Richtlinien fur die Ausstatung und den Betrieb von stra${\beta}$entunneln) time heating temperature curve. The test results showed that the measured temperatures at the t=0 mm depth of PSC slab with precast fire resistance panel during a fire was maximum temperature $367^{\circ}C$, lower than $380^{\circ}C$ (ITA 2004), when damage occurs. Also, at the t=25 mm, the maximum temperature was $239^{\circ}C$, which was lower than the damage temperature of rebar, $250^{\circ}C$. From the results, the use of precast fire resistance panel (t=25 mm) improves fire resistance of PSC structures.

• Journal of the Korea Convergence Society
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• v.6 no.6
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• pp.241-246
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• 2015

In cold winter season, the apparatuses of heating and heater which warm up the interior of a room are necessary element and the used amount of these apparatuses from the year 2000 has been increased abruptly. But, the fire accident and the danger of fire are also increased. Therefore, 3D modelling is done by referring three kinds of the electric heaters as the heaters of ceramic, carbon and near infrared ray sold in the city for the design of more safe heating apparatuses in this study. The thermal analyses with these models are carried out and the durabilities due to the thermal deformation and stress are studied. By the background of the study results derived in this study ultimately, the durabilities of electric heater models due to each shape can be anticipated and contributed to the development of new heating apparatus with more safe resistance to fire. And it is possible to be grafted onto the convergence technique at design and show the esthetic sense.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.1
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• pp.1-13
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• 1997

This paper reports the dynamic analysis of energy consumption for an office building by heat resistance-capacitance method. If a building is divided into several wall components and the wall components is replaced by one thermal capacitance and several thermal resistances, the building becomes an electric circuit. By solving the simultaneous equations of the circuit, the dynamic heat transfer characteristics and the energy consumption rate of the building were predicted. Accuracy of modified BIN method was evaluated by the present resistance-capacitance method. The result shows that modified BIN method overpredicts the heating load of the office building 15%. Annual energy consumptions of equipments(fan, boiler, chiller) for various ventilating control system(CAV, VAV, FCU+VAV, FCU+CAV) were compared. FCU+CAV shows the minimum annual energy consumption.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.205-208
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• 2002

Thermal design is required with considering thermal stability to verify the reliability of electric power device with using IGBT. Numerical analysis is performed to analyzed the change in thermal resistance with respect to the various thermal density of heating element. Correlations between thermal resistance and heat generation density are established. With using these correlations, performance curve is composed with respect to the change in thermal resistance of cooling conditions for natural convection and forced convection. Thermal fatigue is occurred at the Inside and outside of IGBT by repeated heat load. The crack is occurred between base plate and ceramic substrate for the inside. When the crack length is 4mm, the failure is occurred. Therefore, Thermal design method considering thermal density, thermal fatigue resistance is presented on this study and it is expected to thermal design with considering life prediction.