• New & Renewable Energy
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• v.9 no.4
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• pp.3-12
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• 2013

This paper proposes the hybrid fuel cell system that can solve disadvantages of existing fuel cell system and ensure high reliability and high stability. The system consists of PEM fuel cell, Ni-MH battery and power management system. In this system, when the power provided from the fuel cell is higher than the load power, the extra energy may be used to charge the Ni-MH battery. When the fuel cell can not provide enough energy to the load, the shortage of energy will be supplied by the Ni-MH battery. Experimental results show that the output voltage is regulated well during load variations. Also, high system efficiency is achieved.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1984-1989
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• 2008

A powered system with fuel cell is regarded as a high current and low voltage source. Effects of the loads on the electrical power source are important to optimize the integrated power system. The design parameters of the system should be chosen by taking into account the characteristics of the fuel cell, so the costs of the power system at given operating conditions can be reduced. Furthermore, the dynamics characteristic of the system is crucial to acquire performance in applications, particularly interactions between loads and the fuel cell system. Currently, no integrated simulation has been approached to analyze interrelated effects. Therefore, the dynamic models of power conversion system with a PEM fuel cell that includes the PEM fuel cell stack, DC/DC converter and associated controls is developed. Electric lads for the system are derived by using a power theory that separates a load current into active, reactive, distortion or a mixed current component. Dependency of the DC capacitor on the loads are analyzed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.2
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• pp.170-178
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• 2012

This paper is concerned with the development of power amplifier and controller for piezoelectric actuator and sensor used in smart structures. Even though a high-voltage power amplifier is provided in the form of an operational amplifier, a very high DC voltage is still necessary as a power supply. In this study, we propose a low-cost design for the power amplifier including the DC power supply. We also need a controller on which a control algorithm will be mounted. In general, a digital signal processing chip is popularly used because of high speed. However, only commercial product is available for smart structure applications. In this paper, a controller consisting of a DSP and electronic circuits suitable for piezoelectric sensor and actuator pair is proposed. To validate the proposed controller with power amplifier, experiment on smart structure was carried out. The experimental results show that the proposed control system can be effectively used for smart structure applications with low cost.

• New & Renewable Energy
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• v.18 no.3
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• pp.32-42
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• 2022

Rapid spread of intermittent renewable energy has amplified the instability and uncertainty of power systems. The Korea Power Exchange (KPX) promoted efficient management by opening the power brokerage market in 2019. By combining small-scale intermittent renewable energy with a flexible facility through the power brokerage market, the KPX aims to develop a virtual power plant system that will allow the conversion of existing intermittent renewable energy into collective power plants. However, the participation rate of renewable power owners in the power brokerage market is relatively low because other markets such as the small solar power contract market or the Korea Electric Power Corporation power purchase agreement are more profitable. In this study, we used a choice experiment to determine the attributes affecting the participation rate in the power brokerage market for 113 renewable power owners and estimate the value of the power brokerage market. According to the estimation results, a low smart meter installation cost, low profit variations, long contract periods, and few clearances increased the probability of participation. Moreover, the average value of the power brokerage market was estimated to be 2.63 million KRW per power owner.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.12
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• pp.713-715
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• 2005

The work in this paper presents development of fuzzy logic-based energy management strategy for a fuel cell hybrid electric vehicle. In order for the fuel cell system to overcome the inherent limitation such as slow response time and low fuel economy especially at the low power region, the battery system has come to compensate for the fuel cell system. This type of hybrid configuration has many advantages, however, the energy management strategy between power sources is essentially required. For the optimal power distribution between the fuel cell system and the battery system, a fuzzy logic-based energy management strategy is proposed. In order to show the validity and the robustness of suggested strategy, some simulations are performed for the standard drive cycles.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.33-33
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• 2000

In this paper a new distributive control system for BA(Building Automation ) lighting control used on general microprocessors is presented. For optimal lighting control and saving energy, The system have to control the group and pattern lighting control as well as individual light control at one time. Tn this paper, This functions are accomplished with low-cost and simple microprocessor. A plurality of modulated light control terminals are connected to the central control unit through a pair of power line. This power line provide both power and signal to the each terminal and the data is transmitted through cyclic time division multiplex transmission. With this structure a low-cost distributive control system for lighting applications has been achieved, allowing energy and maintenance saving and reliability increase of the light control system.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.2
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• pp.167-174
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• 2016

Even though the differential drag type machines of the vertical wind turbines are a bit less efficient than the lift type machines such as Darrieus type machines, they have an advantage of low starting torque. The flapping blade type wind turbine is a specific type of the differential drag machines, and it has no need for orientation as well as quite low starting torque. This work is to develop an innovative 5kW class flapping type vertical wind turbine system which will be applicable to a hybrid power generation system driven by the diesel engine and the wind turbine. The parametric study was carried out to decide an optimum aerodynamic configuration of the wind turbine blade. In order to evaluate the designed blade, the subscale wind tunnel test and the performance test were carried out, and their test results were compared with the analysis results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.9
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• pp.62-70
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• 2010

Fuel cell system which can solve the environmental problem is receiving attention. To use utility power necessary power conversion system from low voltage that is generated by fuel cell system. because fuel cell has special characteristic of low voltage high current. To improve PCS's efficiency the paralleling method is used. Available the method could reduce the switching loss. But the existing research could not be found optimal result and accompanying several effects. In this study analysis several effects causing the parallel method. The effects have been demonstrated through simulations and experiments.

• Journal of Computing Science and Engineering
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• v.6 no.4
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• pp.310-319
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• 2012

Next generation wireless receivers demand low computational complexity algorithms with high computing power in order to perform fast signal detections and error estimations. Several signal detection and estimation algorithms have been proposed for next generation wireless receivers which are primarily designed to provide reasonable performance in terms of signal to noise ratio (SNR) and bit error rate (BER). However, none of them have been chosen for direct implementation as they offer high computational complexity with relatively lower computing power. This paper presents a low-complexity power-efficient algorithm that improves the computing power and provides relatively faster signal detection for next generation wireless multiuser receivers. Measurement results of the proposed algorithm are provided and the overall system performance is indicated by BER and the computational complexity. Finally, in order to verify the low-complexity of the proposed algorithm we also present a formal mathematical proof.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.1
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• pp.24-29
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• 2004

A new low cost hybrid active filter for thyristor-controlled rectifier load is presented to overcome the high cost problem of the active or the other hybrid active filters. The proposed hybrid active filter which consists of tuned (5th and 7th harmonics) LC passive filters, power factor improvement(PFI) capacitor bank, and active filter compensates power factor as well as harmonic currents. Since most of harmonic currents are filtered by the passive filter and most of reactive power is compensated by the PFI capacitor bank, the power rating of active filter can be minimized, resulting in cost minimization of the proposed hybrid active filter. A 300kVA hybrid active filter system is implemented and tested using 1MVA thyristor rectifier load to verify the operation and performance.