• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.11
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• pp.561-568
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• 2005

This paper proposes a method that distributes the load power and stores the regenerated energy for a hoist-load system using the supercapacitor, an energy storage device. The crane, which is a representative hoist-load system, operates in two modes. The first is the hoist-up mode in which the load container is lifted up: the maximum power is required at the end of acceleration. The second is the hoist-down mode in which the load container is lifted down; the regenerated energy is wasted by the resistor In this paper, the supercapacitor stores the regenerated energy in the hoist-down operation and supplies the peak power demand in the hoist-up operation. The same structure as the commercially available three-phase inverter is proposed as a bidirectional do-dc converter to charge and discharge the supercapacitor. A power control algorithm is proposed to optimize the load sharing between the generator and the supercapacitor. Using the proposed method, it is effected that the generator size can be cut down to one third of the original one; it leads to the reduction of the fuel consumption, noise and air pollution. Simulation and experimental results verify the effectiveness of the Proposed method.

• Journal of Hydrogen and New Energy
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• v.30 no.1
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• pp.43-48
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• 2019

This study investigates the electrochemical characteristics of the hybrid cell that combined the advantageous characteristics of Li secondary battery and supercapacitor, high energy density and high power density, respectively. Electrochemical behaviors of the hybrid cell was characterized by charge/discharge, cycle and impedance tests. The hybrid cell using Li secondary battery and supercapacitor had better discharge capacity and cycle performance than that of using Li secondary battery only. Proper design of such a hybrid cell system is expected to result in substantial benefits to the well being of the Li secondary battery. The hybrid cell involving Li secondary battery for high energy density and supercapacitor for high power density may be the possible solution for future energy storage system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.573-576
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• 2001

In the research fields of energy storage, and more specifically of supplying high powers, electrochemical supercapacitor have been among the most studied systems for many years. One of the possible applications is in electric vehicles. We have been working on electronically conducting polymers for use as active materials for electrodes in supercapacitors. These polymers have the ability of doping and undoping with rather fast kinetics and have an excellent capacity for energy storage. polythiophene (Pth) and polyparafluorophenylthiophene (PFPT) have been chemically synthesized for use as active materials in supercapacitor electrodes. Electrochemical characterization has been performed by cyclic voltammetry and an electrode study has been achieved to get the maximun capacity out of the polymers and give good cyclability. specific capacity values of 7mAh/g and 40mAh/g were obtained for PFPT and poly thiophene, respectively. Supercapacitors have been built to characterize this type of system. Energy storage levels of 260F/g were obtained with Pth and 110F/g with PFPT.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.735-737
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• 2017

An Off grid or remote solar electric systems are an energy supply to our home or to our companies without the utility of Grid at all. Off grid solar systems are very important for those who live in remote locations especially for developing countries where getting the electric grid is extremely expensive, inconvenient or for those who doesn't need to pay a monthly bill with the electric bill in general. The main critical components of any solar power system or renewable energy harvesting systems are the energy storage systems and its charge controller system. Energy storage systems are the essential integral part of a solar energy harvesting system and in general for all renewable energy harvesting systems. To provide an optimal solution of both high power density and high energy density at the same time we have to use hybrid energy storage systems (HESS), that combine two or more energy storage technologies with complementary characteristics. In this present work, design and simulation we use two storage systems supercapacitor for high power density and lithium based battery for high energy density. Here the system incorporates fast-response supercapacitors to provide power to manage solar smoothing and uses a battery for load shifting. On this paper discuss that the total energy throughout of the battery is much reduced and the typical thermal stresses caused by high discharge rate responses are mitigated by integrating supercapacitors with the battery storage system. In addition of the above discussion the off grid solar electric energy harvesting presented in this research paper includes battery and supercapacitor management system, MPPT (maximum power point tracking) system and back/boost convertors. On this present work the entire model of off grid electric energy harvesting system and all other functional blocks of that system is implemented in MATLAB Simulink.

• Clean Technology
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• v.27 no.4
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• pp.277-290
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• 2021

A supercapacitor, also called an ultracapacitor or an electrochemical capacitor, stores electrochemical energy by the adsorption/desorption of electrolytic ions or a fast and reversible redox reaction at the electrode surface, which is distinct from the chemical reaction of a battery. A supercapacitor features high specific power, high capacitance, almost infinite cyclability (~ 100,000 cycle), short charging time, good stability, low maintenance cost, and fast frequency response. Supercapacitors have been used in electronic devices to meet the requirements of rapid charging/discharging, such as for memory back-up, and uninterruptible power supply (UPS). Also, their use is being extended to transportation and large industry applications that require high power/energy density, such as for electric vehicles and power quality systems of smart grids. In power generation using intermittent power sources such as solar and wind, a supercapacitor is configured in the energy storage system together with a battery to compensate for the relatively slow charging/discharging time of the battery, to contribute to extending the lifecycle of the battery, and to improve the system power quality. This article provides a concise overview of the principles, mechanisms, and classification of energy storage of supercapacitors in accordance with the electrode materials. Also, it provides a review of the status of recent research and patent, product, and market trends in supercapacitor technology. There are many challenges to be solved to meet industrial demands such as for high voltage module technologies, high efficiency charging, safety, performance improvement, and competitive prices.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.754-760
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• 2011

In the DC traction system, a large load current of electric railcar leads to a voltage drop when a vehicle starts, and the regenerative power generated by brake system increases the catenary voltage. To minimize the voltage fluctuation during the train operation and make use of the regenerative power, several types of energy storage systems are being studied. The energy storage system that is being recently introduced consists of the supercapacitors for energy storage and the bi-direction DC/DC converter for charge/discharge control. The efficiency of the energy storage system depends on the train operation pattern. In this paper, the operation efficiency of the energy storage system was quantitatively analyzed via simulation study taking consideration of the train operation patterns. The simulation was conducted changing the headway of trains with the energy storage system that uses the bi-direction DC/DC converter and supercapacitor. The simulation results showed that the operation efficiency of the energy storage system increases as the headway increase.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.994-995
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• 2008

It is possible to suppress voltage drops, power loading fluctuations and regeneration power lapses for DC railway systems by applying an energy storage system. A electric double layer capacitor (EDLC) of the rapid charge/discharge type has been developed and used in wide ranges. It has a long life, high efficiency and maintenance free/low pollution features as a new energy storage element. In this paper, an efficient charge and discharge control method of a bidirectional DC-DC converter using the supercapacitor is proposed.

• Journal of Electrical Engineering and Technology
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• v.7 no.2
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• pp.207-211
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• 2012

Spinel-$Li_4Ti_5O_{12}$ was successfully synthesized by a solid-phase method at 800, 850, and $900^{\circ}C$ according to the $Li_4Ti_5O_{12}$ cubic spinel phase structure. To achieve higher EDLC energy density with the $Li_4Ti_5O_{12}$, the negative electrode of the hybrid supercapacitor was studied in this work. The electrochemical performances of the hybrid supercapacitor and EDLC were characterized by constant current discharge curves, c-rate, and cycle performance testing. The capacitance (1st cycle) of the hybrid supercapacitor and EDLC was 209 and 109 F, respectively, which is higher than EDLC. The capacitance of the hybrid supercapacitor decreases from 209 F to 101 F after 20 cycles when discharged at several specific current densities ranging from 1 to 10 A. In contrast, capacitance of the EDLC hardly decreases after 20 cycles. Results show that hybrid supercapacitor benefits from the high rate capability of supercapacitor and high capacity of the battery. Findings also prove that the hybrid supercapacitor is an energy storage device where the supercapacitor and the Li ion secondary battery coexist in one cell system.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.6
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• pp.481-487
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• 2009

This paper proposes a regulation method of DC line voltage for urban transit system fluctuated during the acceleration or deceleration by using supercapacitor. Supercapacitor is modelled electrically under the assumption of three different time constants of RC circuits with variable capacitances depending on the voltage. And its parameters are determined by the experimental measurements. The energy storage system using supercapacitors is installed based on this model, and the proposed model is tested through the simulations and experiments, and the controller for charging and discharging is designed. Finally, it is tested at Kyoungsan test site for the urban light rail road system and the energy saving effect is evaluated economically.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.8 s.251
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• pp.756-763
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• 2006

PEMFC has several technical problems such as water management, long term stability and performance degradation as. PEMFC has been studied not only to solve water management, but also to generate power in stable manner to system by using a hybrid system with auxiliary energy storage device. The purpose of this study is to couple PEMFC with supercapacitor to make a hybrid system and to design and test control strategies for stable power generation in case of changing output power. The polarization curve and dynamic behaviors while changing power were investigated to find out characteristics of PEMFC stack. A DC/DC converter was fabricated in order to increase fuel cell and supercapacitor voltage and to charge supercapacitor. We found that the operation strategy 2 was recommended to the system because of solving water management problem and increasing the dynamic behavior.