• Proceedings of the KSR Conference
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• 2008.11b
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• pp.619-625
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• 2008

Electrical Power supply System conditions of korea high speed train consists of main transformer, four AC-DC PWM converter of Auxiliary Block, Battery Charger in Power Car and Trailer Car, Trailer Inverter, Auxiliary inverter. Main transformer, at nominal voltage of 25kv supplied to secondary winding nominal output Voltage 383Vac, The Auxiliary block consists of AC-DC converters for generating 670VDC power, Auxiliary inverters for ventilation and air compressor, Trailer car inverter provide three phase power supplies at 440Vac for air conditioning and heating. The Battery charger Trailer and Power car supplies 72VDC all necessary equipment to energize the trainset equipment and suppy essential control. This Paper introduces the combined test results of the power supply system for korea high speed train. The main purpose of this combined test is to verify the performance of the power supply system that is designed to operate up to full load test.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.12
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• pp.36-46
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• 2008

This paper is to study on the Construction of Test circuit and Unification of Experiment Method for high voltage gas-insulated load switch using high power testing system The high power testing system is a equipment to verify electrical and mechanical performance on electrical product. The system consist of short-circuit generator, back-up breaker, making switch, impedance, high voltage transformer, low voltage transformer, measuring and protection system, etc. Using this system, we can test related to high power, for example, short-time current test, active load Current test, magnetizing Current test, capacitive current test, closed loop current test, etc. Standards of high voltage gas-insulated load switch that is in use domestic distribution line are ES 5925-0002, IEC 60265-1, IEC 62271-1 and IEEE C 37.74, etc. In this paper, we standardized on the test procedure, organization of test circuit and analysis of measured data prescribed many difference standards, and applied this test method to 600[MVA] high power testing system. So that we can test the load switch satisfied standards.

• Journal of Power Electronics
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• v.6 no.1
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• pp.1-7
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• 2006

This paper is a record of the study on a high efficiency and high power chopper based on the new soft switching method QRAS (Quasi~resonant Regenerating Active Snubber) designed for a Fuel Cell Electric Vehicle (FCEV). This power chopper is basically proposed for 25kHz soft switching. To confirm the practicality and effectiveness of the converter, the fabrication of a prototype-model using IGBTs was completed. Additionally, a 8kW rating test, a light load test, a current discontinuous mode test and a stable operation resonance test was completed. The circuit geometry, the basic operation, and the 8kW one-tenth-prototype test results are reported with a $97.5\%$ efficiency measurement.

• Journal of Applied Reliability
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• v.14 no.2
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• pp.97-102
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• 2014

Radar is an object-detection system that uses radio waves to determine the range, altitude, direction, or speed of objects. High power amplifier Module is the most critical part of the high-power radar transmitter systems. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. Research related to radar has been conducted in various fields according to improvement of the communication technology. But only performance-originated technology development has been dashed; study concerning environment duality and safety concerning reliability are still insufficient. In general, radar module is exposed to the outside, on the means of moving or fixed in a certain place. It should be guaranteed sufficient immunity for a variety of environmental stresses that can occur in the outdoor. HALT is a great process used for quickly finding failure mechanisms in a hardware design and product. By applying various kinds and extreme level of stresses, we can find the operating limits of products. In thesis, we conducted HALT test of the high power amplifier modules which used in military and automotive radar. After the test, we analyzed environmental weaknesses of high power amplifier modules using conventional construction data.

• Journal of the Korea Society of Computer and Information
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• v.23 no.11
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• pp.67-74
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• 2018

The verification for the design limit margin of the power device for the information communication and surveillance systems using HALT(Highly Accelerated Life Test) reliability test is described. The HALT reliability test performs with a step stress method which change condition until the marginal step in a design and development phase. The HALT test methods are the low temperature(cold) step stress test, the high temperature(hot) step stress test, the thermal shock cyclic stess test, and the high temperature destruct limit(hot DL) step stress test. The power device is checked the operating performance during the test. In this paper, the HALT was performed to find out the design limit margin of the power device.

• Physical Therapy Rehabilitation Science
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• v.10 no.4
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• pp.457-462
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• 2021

Objective: This study analyzed the correlation between uni-standing balance ability, jumping ability, and anaerobic lower extremity power of high school Taekwondo players. Design: Cross-sectional study Methods: Two high schools recruited 36 taekwondo players, but 5 were dropped due to personal circumstances and preparations for the tournament, so the number was counted as 31. In order to test uni-standing balance ability, the Romberg test was performed using Biorescue to measure the sway area. In order to test jumping ability, standing long jump and standing highjump were measured. For anaerobic lower extremity muscle power test, the peak power and average power were measured through 30-second pedaling using a Wingate system bicycle. Results: Participants did not show any correlation with other measures in the uni-standing balance ability test (p>0.05). Looking at the correlation in the standing long jump, standing high jump (r=0.892, p<0.05), anaerobic peak power (r=0.698, p<0.05), anaerobic average leg power (r=0.662, p<0.05) showed a positive correlation. Looking at the correlations in the standing high jump, anaerobic peak power (r=0.663, p<0.05), anaerobic average power (r=0.697, p<0.05) showed a positive correlation. Looking at the correlation in the anaerobic peak power, average power (r=0.785, p<0.05) showed a positive correlation. Conclusions: This study shows that balance ability and anaerobic leg strength are independent of each other. The results of this study can be used as basic data for the training plan of high school taekwondo players in the future.

• Journal of Applied Reliability
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• v.12 no.3
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• pp.177-186
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• 2012

This paper presents a comparison of the failure mechanism for high power converted white LEDs(3W) with the commercially available YAG:Ce and silicate phosphor. We carry out the normal aging life test for 10,000 hours, the high temperature aging test for 8,000 hours, the high temperature and humidity aging test for 8,000 hours and the current aging testing for 5,000 hours. The optical and electrical parameters of LEDs were monitored, such as lumen, correlated color temperature (CCT), chromaticity coordinates(x, y), thermal resistance, I -V curve and spectrum intensity. The stress induced a luminous flux decay on LED in all experiments and causes a failure. So we try to find out what's a main failure mechanism for a high power LED.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.961-963
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• 2000

Most of the application standard of the low-voltage devices have applied one the IEC standard another the UL standard. European union applied the IEC60947-1 standard has not exceed 1000V a.c. or 1500V d.c.. Therefore. it is necessary to the low-voltage device has expended for rated operational voltage with our products. The export of European market shall be made for the CE-Marking in accordance with IEC60947-1 ( Low-voltage switchgear and controlgear). We shall be considered for the requirement with the IEC standard. In this time to study for power supply system at EU ( European union. At that time for design and development in order to the construction and test method among the study for the rated insulation voltage at less then 690V.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.6
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• pp.279-286
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• 2000

The stud bolts tend to degrade faster by high temperature(over 45$0^{\circ}C$). Therefore, replacement cycle inspection of stud bolts were carried out various method such as ultrasonic test(UT), magnetic test(MT), wobble test, visual test and hardness test. Especially, wobble test method has been applied to determine replacement evaluation criteria of stud bolt after long time operation. We applied three different methods on the three site and the obtained data are compared with the results from the evaluation methods. From the results, the replacement criteria for stud bolts under high temperature in power plants are proposed.

• Nuclear Engineering and Technology
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• v.53 no.4
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• pp.1345-1356
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• 2021

Damage to nuclear power plants causes human casualties and environmental disasters. There are electrical facilities that control safety-related devices in nuclear power plants, and seismic performance is required for them. The 2016 Gyeongju earthquake had many high-frequency components. Therefore, there is a high possibility that an earthquake involving many high frequency components will occur in South Korea. As such, it is necessary to examine the safety of nuclear power plants against an earthquake with many high-frequency components. In this study, the shaking table test of electrical facilities was conducted against the design earthquake for nuclear power plants with a large low-frequency components and an earthquake with a large high-frequency components. The response characteristics of the earthquake with a large high-frequency components were identified by deriving the amplification factors of the response through the shaking table test. In addition, safety of electrical facility against the two aforementioned types of earthquakes with different seismic characteristics was confirmed through limit-state seismic tests. The electrical facility that was performed to the shaking table test in this study was a motor control center (MCC).