• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.4
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• pp.279-285
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• 2019

This study proposes an enhanced switching pattern that can improve energy transfer efficiency in an active cell-balancing circuit using a multiwinding transformer. This balancing circuit performs cell balancing by transferring energy stored in a specific cell with high energy to another cell containing low energy through a multiwinding transformer. The circuit operates in flyback and buck-boost modes in accordance with the energy transfer path. In the conventional flyback mode, the leakage inductance of the transformer and the stray inductance component of winding can transfer energy to an undesired path during the balancing operation. This case results in cell imbalance during the cell-balancing process, which reduces the energy transfer efficiency. An enhanced switching pattern that can effectively perform cell balancing by minimizing the amount of energy transferred to the nontarget cells due to the leakage inductance components in the flyback mode is proposed. Energy transfer efficiency and balancing speed can be significantly improved using the proposed switching pattern compared with that using the conventional switching pattern. The performance improvements are verified by experiments using a 1 W prototype cell-balancing circuit.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.1812-1820
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• 2017

This paper analyzes a symmetric active cell balancer for a battery management system. The considered cell balancer uses a forward converter in which the circuit structure is symmetric. This cell-balancing method uses fewer switches and is simpler than the previously proposed active cell-balancing circuits. Active power switches of this cell-balancing circuit operate simultaneously with the same pulse width modulation signals. Therefore, this cell-balancing circuit requires less time to be balanced than a previous bidirectional-forward-converter-based cell balancer. This paper analyzes the operational principles and modes of this cell balancer with computer-based circuit simulation results as well as experimental results in which each unbalanced cell is equalized with this cell balancer. The maximum power transfer efficiency of the investigated cell balancer was 87.5% from the experimental results. In addition to the experimental and analytical results, this paper presents the performance of this symmetric active cell-balancing method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.11
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• pp.1931-1936
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• 2016

In this paper, we analyzed causes of accidents that recently increased in the illegal and defective LED lamps. They were analyzed by the electrical characteristics calculation and reappearance experiments. The causes of the accidents were analyzed from the circuit affected by the variation of voltage, current and power by harmonics. We drew a conclusion for electrical safety in illegal or degraded LED lamps from the analysis result. The management factors for electrical safety in LED lamps were harmonics, reactive power and power factor. It is possible to secure the electrical safety through monitoring of power factor in failure products and available in smart meters or smart distribution boards.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2839-2844
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• 2008

A PEMFC(proton exchange membrane fuel cell) is a good candidate for residential power generation to be cope with the shortage of fossil fuel and green house gas emission. The attractive benefit of the PEMFC is to produce electric power as well as hot water for home usage. Typically, thermal management of vehicular PEMFC is to reject the heat from the PEMFC to the ambient air. Different from that, the thermal management of PEMFC for RPG is to utilize the heat of PEMFC so that the PEMFC can be operated at its optimal efficiency. In this study, dynamic thermal management system is modeled to understand the response of the thermal management system during dynamic operation. The thermal management system of PEMFC for RPGFC is composed of two cooling circuits, one for controling the fuel cell temperature and the other for heating up the water for home usage. Dynamic responses and operating strategies of the PEMFC system are investigated during load changes.

• Journal of the Society of Disaster Information
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• v.19 no.4
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• pp.844-850
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• 2023

Purpose: This paper is about the development of a short-circuit protection power supply device using incandescent bulbs and its application for educational materials. This article, which considers electrical safety and energy conservation at the same time, has many kinds of potential applications for both educational and industrial areas. The above mentioned short-circuit protection power supply device using incandescent bulbs enhances safety and efficiency compared to normal current power supply devices. Additionally, as an educational materials, it can be used for electric safety training, and provides practical electrical safety knowledge on our actual life. Method: Using incandescent bulbs, design new type of short-circuit protection power supply device, and through verifying the function and safety of the device, make new type device, and applying it for an educational tool. Conclusion: This study is to develop new type of power supply device, and verify the possibility of the application for the device as an educational materials. Through this research, show an innovative solution, which contribute to electrical safety and energy conservation, and open the potential possibility on educational and industrial sectors.This kind of research is expected to contributes to enhanced research, and education on electrical safety and energy conservation management.

• Journal of Power Electronics
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• v.16 no.2
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• pp.414-424
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• 2016

This paper proposes a novel high-efficiency high-step-up interleaved converter with a voltage multiplier, which is suitable for electric vehicle power management applications. The proposed interleaved converter is capable of achieving high step-up conversion by employing a voltage-multiplier circuit. The proposed converter lowers the input-current ripple, which can extend the input source's lifetime, and reduces the voltage stress on the main switches. Hence, large voltage spikes across the main switches are alleviated and the efficiency is improved. Finally, a prototype circuit with an input voltage of 24 V, an output voltage of 380 V, and an output rated power of 1 kW is implemented and tested to demonstrate the functionality of the proposed converter. Moreover, satisfying experimental results are obtained and discussed in this paper. The measured full-load efficiency is 95.2%, and the highest measured efficiency of the proposed converter is 96.3%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.627-633
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• 2015

We designed of a LDO regulator with a OVP and UVLO protection function for a PMIC. Proposed LDO regulator circuit consists of a BGR reference circuit, an error amplifier and a power transistor and so on. The proposed LDO regulator is designed for low voltage input power protection. Proposed LDO circuit generated fixed 2.5 V from a supply of 3.3V. It was designed with 3.3 V power supply using a $0.35{\mu}m$ CMOS technology. SPICE simulation results showed that the proposed circuit provides 0.713 mV/V line regulation with output 2.5 V ~ 3.9 V and $8.35{\mu}V/mA$ load regulation with load current 0 mA to 40 mA.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1067-1070
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• 2002

The maximum demand power management system(the demand controller) is an equipment for demand management. If the pre-estimated load is over the preset power, the demand controller make warnings and break the load circuit according to predefined priority. Then consumption power is maintained below the maximum demand power level. The DTU receives the control commands from demand controller, and then controls loads. In this paper, the power line cables are used for communication between the demand controller and DTUs and monitoring PC. The experiments show that the proposed system is compatible with the conventional system, and feasible for new or remodeling plant.

• Journal of the Korea Safety Management & Science
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• v.19 no.4
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• pp.309-316
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• 2017

Recently, the outboard engine system of internal combustion engine is widely used in the field of small ship propulsion. However, the internal combustion engine has serious problems of energy depletion and environmental problems, so electric propulsion methods are being studied. In this paper, we have developed important motors and controllers of electric propulsion system for small marine outboard motors. The motor design was performed through the motor characteristics analysis method, and the 30Kw system was developed through the BEMF processing circuit and the power conversion circuit by the embedded microprocessor. This study was carried out through government supported projects and achieved quantitative targets through accredited institutions.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.1
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• pp.16-24
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• 2019

The performance of the battery management system (BMS) algorithm is important for ensuring the stability and efficient operation of battery packs. Such a performance is determined by the internal parameters of the electrical equivalent circuit model (EECM). This study proposes a performance improvement and verification of battery parameters for the BMS algorithm using electrical experiments and tools. The parameters were extracted through electrical characteristic experiments, and an EECM based on Ah counting was designed. Simulation results using the EECM were compared with actual experimental data to determine the best parameter extraction method.