• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.758-761
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• 2003

We have designed 5 V/500 mA transless type power module by using semiconductor switching technique, key technique for small size of power supply system. The power module is suitable to a small sized electronic system using a single power supply. It is composed of switching circuit using voltage drop type chopper method, control circuit, voltage detect circuit, and constant voltage circuit, and is fabricated to hybrid-IC type. The switching regulator power supply circuit, designed in this study, has satisfied the electrical characteristics of 5 V/500 mA transless type power module.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1009_1010
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• 2009

This paper presents a power supply system with pre-regulator using zero voltage switching (ZVS) interleaving two-transistor forward converter for high input voltage and high power application. A SMPS has a advantage that a good efficiency, small size and light weight but has a noise problem. A linear power supply system has a advantage that a good stability, low ripple and noise but has a disadvantage that a big size, low efficiency and heat problem. To alleviate these problems, we propose an power supply system using dual ZVS interleaving two-transistor forward pre-regulator. The proposed converter is verified on a 1kW, 50kHz experimental prototype.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.394-400
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• 2007

This thesis aims the development of power supply for the BTS of Mobile Telecommunication system. Specially, it receives AC power and it can be possible both supply the uninterrupted and stabile DC Power to BTS and simultaneously maintain full charging the back-up battery that is used in case failing AC power supply. In addition, easy maintenance is also the main purpose of it regardless of front and left side except rear side. In these days, it needs more small size power supply system in order to comply with the user needs regarding more easy maintenance and more less space as become smaller main telecommunication systems. This system can be installed close to wall and support more easy maintenance and it was considered easy expansion in case when it needs.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.11
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• pp.628-634
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• 2002

A capacitor-charging power supply using high frequency inverter technology is strongly recommended for the charging section of the pulsed power supplies. A high frequency inverter swiching makes the overall system size small. The command-charging feature can guarantee the higher reliability of switching function. The protection circuit can be easily included in the system and the good regulation of charging voltage can be acieved by the feedback system. Several modules can be stacked to supply required output power and a failed module can be easily replaced. A 50-kV, 35-kW capacitor charging power supply is developed. In this paper the detailed design and test results of a prototype unit are presented.

• JSTS:Journal of Semiconductor Technology and Science
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• v.10 no.3
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• pp.165-175
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• 2010

This paper presents a fine-grain supply-voltage-control scheme for low-power FPGAs. The proposed supply-voltage-control scheme detects the critical path in real time with small overheads by exploiting features of asynchronous architectures. In an FPGA based on the proposed supply-voltage-control scheme, logic blocks on the sub-critical path are autonomously switched to a lower supply voltage to reduce the power consumption without system performance degradation. Moreover, in order to reduce the overheads of level shifters used at the power domain interface, a look-up-table without level shifters is employed. Because of the small overheads of the proposed supply-voltage-control scheme and the power domain interface, the granularity size of the power domain in the proposed FPGA is as fine as a single four-input logic block. The proposed FPGA is fabricated using the e-Shuttle 65 nm CMOS process. Correct operation of the proposed FPGA on the test chip is confirmed.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.67 no.3
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• pp.137-142
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• 2018

Energy harvesting technology is drawing attention as a means of collecting various eco-friendly energy and accumulating residual energy. Recently, differential power processing (DPP) is being developed as part of energy harvesting. This is being studied as a solution to the loss of power generation between power modules and the problems caused by module small losses depending on the size of power production. In this paper, we propose the necessity of the DPP by comparing and analyzing energy harvesting related module integration system and power supply efficiency of DPP. The power efficiency of the converter and the power difference between the wind power and the photovoltaic power supply have been changed to demonstrate the effectiveness of the proposed system.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.2
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• pp.68-75
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• 2011

The purpose of this paper is to suggest a supplier and buyer's pricing decision strategy model with discount-policy over a long-term replenishment contract in a supply chain environment by small and medium size manufacturing company. We assume that the buyer has a superior economic power over a supplier and each agent in a supply chain is unaware of each other. The supplier proposes pricing decision strategy to induce the buyer to choose the terms of contract for the benefit of the supplier. Then buyer decides the terms of contract to maximize her profit considering supplier's discount-policy. We also present a numerical example to illustrate the efficiency of pricing decision strategy.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.1
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• pp.1-8
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• 2018

A problem exists in the conventional transportation cart applications, in which an external power supply with mechanical contact connection (bus bar connection) is required to drive the motor. Therefore, continuous effort for maintenance is required, aside from the expensive bus bar connector. To solve this problem, a self-electricity-generated transportation cart system without bus bar has recently been introduced. In this system, a battery needs to store the power of the generated wheel, and a boost converter, which converts the low battery voltage to high bus voltage to drive the motor inverter, is necessary. However, since the instantaneous large current required for starting the motor is supplied from the battery, a battery with large size and volume should be adopted to withstand this large current. In this study, a boost converter that can supply a large instantaneous current by using super Capacitor string is proposed. The proposed converter can be realized with a small size and volume compared with the conventional battery-fed boost converter. Operational principles, analysis, and design of the proposed converter are presented, and experimental results are provided to validate the proposed converter.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.345-350
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• 2014

DC electrolytic capacitor is widely used in the power converter including PWM inverter, switching power supply and PFC Boost converter system because of its large capacitance, small size and low cost. In this paper, basic characteristics of DC electrolytic capacitor vs. frequency is presented and the real-time estimation scheme of ESR and capacitance based on the bandpass filtering is adopted to the single phase boost converter of uninterruptible power supply to diagnose its split dc-link capacitors. The feasibility of this real-time failure prediction monitoring system is verified by the computer simulation of the 5[kW] singe phase PFC half-bridge boost converter.

• Transactions of The Korea Fluid Power Systems Society
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• v.5 no.4
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• pp.10-16
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• 2008

In this paper, the authors benchmark a servo valve model for the fuel supply system of Auxiliary Power Unit (APU) in the KHP helicopter. This valve is directly driven with a torque motor, and the size of small gap controlled by a flapper can make change of flow rate under given pressure drop between inlet and outlet. CFD analyses using a commercial code, ANSYS-CFX 10 are performed for the series of three-dimensional models at various openness conditions. The computational results on simplified models show that CFD can play a fine roll in the design of flow path as well as in the estimation of flow force due to its precision and good repeatability. Consequently, the CFD analysis helps valve designers to understand its flow characteristics from the basis of physical fundamentals.