• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.5
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• pp.1068-1073
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• 2004

5 V/500 mA transless type power module was designed by using a semiconductor switching technique for a small-sized electric power source. It used voltage drop type chopper method, and is composed of switching circuit, control circuit, voltage detect circuit, and constant voltage circuit. The switching power module which is designed in this study, showed load regulation of 0.2 V, line regulation of 0.1 V, output ripple of 85 mVp-p, switching frequency of 64.7 kHz, maximum power efficiency of 58 %, and satisfied its reliability and EMC test.

• Proceedings of the KIEE Conference
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• 2005.11c
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• pp.131-135
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• 2005

Stabilization of electric power is the most important thing is such place as computing center having business critical equipment. However, ability to cope with electrical quality shift and power failure is very weak from UPS output side to load in those electricity system, though UPS is generally used for power stabilization. this problem can be solved by duplication of power source using newly configured UPS and small sized transfer switch even in case of UPS failure.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.7
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• pp.1124-1128
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• 2021

As regulations of emissions from ships become more stringent, electric propulsion systems have been increasingly used to solve this problem in vessels ranging from large merchant ships to small and medium-sized ships. Methods for improving the efficiency of the electric propulsion system include the improvement of power sources; the use of a system linked to environmentally friendly power sources, such as batteries, fuel cells, and solar power; and the development of hardware and control methodology for rectifiers, power conversion devices, and propulsion motors. The method using a phase-shifting transformer with diodes has been widely used for rectification. Power semiconductor devices with grid connection to an environmentally friendly power source using DC distribution, a variable speed power source, and the application of small and medium-sized electric propulsion systems have been developed. Accordingly, the demand for active front-end (AFE) rectifiers is increasing. In this study, a method using a neural network rather than a conventional proportional-integral controller was proposed to control the AFE rectifier. Tested controller data were used to design a neural network controller trained through MATLAB/Simulink. The neural network controller was applied to a rectification system designed using PSIM software. The results indicated the effectiveness of improving the waveform and power factor DC output stage according to the load variation. The proposed system can be applied as a rectification system for small and medium-sized environmentally friendly ships.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.2
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• pp.131-136
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• 2021

A DC motor is an important driving source used in a wide range along with an induction motor. Although the structure is complex and has disadvantages in terms of maintenance, most of the demands are given to induction motors as a power source in the industry today, but due to its excellent control performance, DC motors are constantly being used as small-sized control motors. In addition, DC motors with a structure capable of high-power and high-efficiency operation are being developed with the development of magnetic materials as a structure capable of using a permanent magnet in a armature. In addition, the configuration of the controller is simpler than that of an induction motor using an inverter, and the demand for a DC motor is still not negligible, so it is still occupied as an important power source. Considering these trends, this paper attempts to investigate the control performance of DC motors through hardware implementation such as modeling through simulation, PWM generation circuit and electric motor circuit using EPLD, and PI control using processor.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.5
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• pp.21-30
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• 2008

The fuel cell generation convert fuel source, and gas directly to electricity in an electro-chemical process. Unlike traditional and conventional turbine engines, the process of fuel cell generation do not burn the fuel and run pistons or shafts, and it has not revolutionary machine, so have fewer efficiency losses, low emissions and no noisy moving parts. A high power density allows fuel cells to be relatively compact source of electric power, beneficial in application with space constraints. In this system, the fuel cell itself is nearly small-sized by other components of the system such as the fuel reformer and power inverter. So, the fuel cell energy's stationary fuel cells produce reliable electrical power for commercial and industrial companies as well as utilities. In this paper, a fuel cell system has been modeled using PSCAD/EMTDC to analyze its electric signals and characteristics. Also the power quality of the fuel cell system has been evaluated and the problems which can be occurred during its operation have been studied by modeling it more detailed. Particularly, we have placed great importance on its power quality and signal characteristics when it is connected with a power grid.