• Journal of the Korean Electrochemical Society
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• v.12 no.2
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• pp.119-130
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• 2009

This article reviews recent R&D trends in SOFC development with an emphasis on industries that can produce the SOFC stack and power generation system. SOFC is an electrochemical device that can convert the chemical energy of fuel into the electrical energy with environment friendly system and high efficiency. SOFC power generation system could be classified as the portable power generation system, auxiliary power unit(APU), residential power generation(RPG) and large size distributed power generation. In the case of more than 10kW system, the major R&D trends are focused on the tubular type SOFC system with high efficient and long term stability to meet the commercialization of SOFC power generation system.

• Journal of Power Electronics
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• v.17 no.2
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• pp.490-500
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• 2017

Fuel cell (FC) is a promising power supply in electric vehicles (EV); however, it has poor dynamic performance and short service life. To address these shortcomings, a super capacitor (SC) is adopted as an auxiliary power supply. In this study, the frequency decoupling control method is used in electric vehicle energy system. High-frequency and low-frequency demand power is provided by SC and FC, respectively, which makes full use of two power supplies. Simultaneously, the energy system still has rapidity and reliability. The distributed power system (DPS) of EV requires DC-DC converters to achieve the desired voltage. The stability of cascaded converters must be assessed. Impedance-based methods are effective in the stability analysis of DPS. In this study, closed-loop impedances of interleaved half-bridge DC-DC converter and phase-shifted full-bridge DC-DC converter based on the frequency decoupling control method are derived. The closed-loop impedance of an inverter for permanent magnet synchronous motor based on space vector modulation control method is also derived. An improved Middlebrook criterion is used to assess and adjust the stability of the energy system. A theoretical analysis and simulation test are provided to demonstrate the feasibility of the energy management system and the control method.

• Nuclear Engineering and Technology
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• v.56 no.1
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• pp.216-221
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• 2024

Ion cyclotron range of frequency (ICRF) heating system is an important auxiliary heating method in the experimental Advanced Superconducting Tokamak (EAST). In EAST, several megawatts of power are transmitted with coaxial transmission lines and coupled to the plasma. For the long pulse and high power operation of the ICRF waves heating system, it is very important to effectively control the power and initial phase of the ICRF signals. In this paper, a power and phase feedback control system is described based on field programmable gate array (FPGA) devices, which can realize complicated algorithms with the advantages of fast running and high reliability. The transmitted power and antenna phase are measured by a power and phase detector and digitized. The power and phase feedback control algorithms is designed to achieve the target power and antenna phase. The power feedback control system was tested on a dummy load and during plasma experiments. Test results confirm that the feedback control system can precisely control ICRF power and antenna phase and is robust during plasma variations.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.250-252
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• 1999

It is certain that the power qualify will be very important at 21 century. Especially instant power shortage or power fault will occur serious problems. Accordingly stable power supplication is very technical problem. There are many way to make stable supplication as auxiliary generator, but this is long time delay complement. To solve this problem the superconducting magnetic energy storage is introduced. High Tc superconductor is more commercial.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.5
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• pp.229-237
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• 2001

Until recent years, most of the researches for motor drives focus on the high performance drive of the three phase induction motor, and that of the single phase induction motor(SPIM) is out of interest. The SPIM is widely used at low power level because it has the simple construction and economic advantage. In general such machine has both main winding and auxiliary winding. Conventionally, these winding are fed by only one single phase source, and the speed of the motor is not controlled. The SPIM with an auxiliary winding can be treated as an asymmetrical two phase machine. In this paper the space vector Equivalent circuit of SPIM is derived. For vector control of the SPIM the stator current must be decoupled into the flux producing component and the torque producing component. To accomplish decoupling control, the conventional method requires complex calculation and large computation time. We proposed the equivalent circuit referred to the rotor side, in this case only the stator resistances in the direct axis and the quadrature axis are different each other and the other parameters are represented to be equal. Thus the decoupling of the stator current is similar to that of the three phase induction motor. In this paper, the novel vector control system of the single phase induction motor is proposed. To verify the feasibility of this scheme, simulation and experimentation are carried out. The results prove the excellent characteristics for the dynamic response, which confirms the validity of the proposed system.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.99-105
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• 2002

About 70% of energy input to internal combustion engine is rejected to atmosphere by heat. By utilizing this waste heat, a plenty of energy can be conserved in nationwide. One of possible ways is the thermoelectric generation to utilize engine's waste heat to provide auxiliary electric power. Under th is concept, we have been developing the thermoelectric generation system to replace the alternator by converting the waste heat in the engine's exhaust directly to electricity This system may reduce the shaft horse power of the engine, then improves the vehicle fuel economy and the exhaust emissions. In the present study, the characteristics of the electric energy and exhaust heal energy in city and highway mode driving conditions are analysed by using a gasoline passenger car. These results would be used to determine the optimum design parameters of the thermoelectric generation system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.360-368
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• 2007

This paper is concerned with the development of piezoelectric energy harvesting device. Literature survey was carried out to investigate the state-of-art technology regarding piezoelectric energy harvesting method. It shows that the piezoelectric energy harvesting system has been researched as the needs for the auxiliary power system grow for ubiquitous sensor node. In this study, the piezoelectric energy harvesting system was constructed and the corresponding electric circuit was also built to investigate the power characteristics. Experimental results show that it can charge the small battery with ambient vibrations but still needs an effective mechanism to collect ambient energies.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.4
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• pp.330-336
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• 2012

In this paper, novel zero-voltage-transition(ZVT) synchronous buck converter of pulse-width-modulation(PWM) method is proposed to utilize auxiliary circuit. In this proposed scheme, designed to operate low output voltage for portable system and applied synchronous scheme to improve efficiency. Also proposed circuit is designed to do soft-switching operation in every switch. In this paper, the circuit operation is explained and analysed, and design guidelines are presented. To verify the availability of the proposed circuit, experiment and simulation is carried out.

• 전기의세계
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• v.23 no.1
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• pp.73-78
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• 1974

Digital simulation algorithms and program for multimachine dynamic stability have been developed which represent the effects of machines much more complety than have been available previously. Emphasis is given to the savings of the memory spaces required, thus making it possible to use a small computer with limited capacity of core storage (without auxiliary storage). Both d- and q- aris quantities are fully represented, and the speed-governing and voltage-regulating system available are ertensive, thus allowing a very close approximation to any physical system. Facilities for dynamic and nonlinear loads are also included. The computational algorithms and program developed have been shown to be extensive and complete, and are very desirable features minimizing memory spaces for stability calculations. The capabilities have been demonstrated by several case studies for an actual power system of 44 generators, 22 loads and 33 buses. About 13-K words of memory spaces have been required for the case studies on the basis of two words per real variable and a word per integer variable.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.183-186
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• 2001

This paper describes the optimal operation scheduling of total cogeneration system which is interconnected with combined heat power plant of utility and district heat devices. The numerical modeling about the cogeneration system and the auxiliary thermal energy devices are established and simulation is carried out by LINDO program in order to minimize the operation cost under the national viewpoint. The results reveal that the established numerical modeling and the operation strategy can be effectively applied to the total cogeneration systems to reduce the energy cost.