• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.9
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• pp.1306-1314
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• 2015

This paper deals with a switching method of a three-phase interleaved bidirectional DC-DC converter to obtain high efficiency in wide load range. The proposed soft-switching method provides ZVS and ZCS at turn-on, and ZVS at turn-off of the switch as well as considerably reduced conduction loss in light load. Simulation and experiment are carried out with a bidirectional DC-DC converter having the power rating of 3 [kW], and those results show the validity of the proposed switching method.

• Journal of the Korean Institute of Telematics and Electronics
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• v.14 no.4
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• pp.15-21
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• 1977

In this paper, an analogical method for measuring the electrical characteristics of the silent discharge in the Na2CO3 electrolyte is proposed by using an electrical equivalent model which consist of charging and discharging circuits. The electrical equivalent model is constructed with the use of zener diode and capacitor, and the electrical characteristics can be obtained by the voltage and charge traces which appear a simple parallelogram on the oscilloscope. The area enclosed by the parallelogram could be considered of the energy input per cycle, and is independent of the applied voltage waveform but dependent on the maximum applied voltage.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.6
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• pp.727-737
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• 2014

This paper presents the design of Fuzzy PI controller that is used at BESS(Battery Energy Storage System) charging and discharging process for islanded operation in microgrid. Most of the PI controllers have fixed PI gains, but real-time updated gains are applied to PI controller using Fuzzy logic in this paper. The performances of suggested Fuzzy PI controller are simulated by PSCAD/EMTDC. As a result, output characteristics of ESS applied real-time updated gains to PI controller are faster than those of using fixed gains.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.43-45
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• 2020

본 논문에서는 급속 충전 시 배터리의 상한 온도를 초과하지 않는 최대 가용 충전 전류의 실시간 추정 알고리즘을 제안한다. 제안하는 알고리즘은 배터리 열 모델을 기반으로 상한 온도에 도달하는 발열량을 추정하고, 충전 상태에 따른 내부 저항의 변화 양성을 고려하여 최대 급속 충전 전류를 도출한다. 알고리즘의 유효성을 검증하기 위하여 전기자동차용 배터리 팩을 이용한 시뮬레이션 및 실험을 진행한다.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.49-51
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• 2020

본 논문에서는 전기자동차 급속 충전 시 배터리 팩의 온도 모사를 위한 열 모델링 기법을 제안한다. 배터리 등가 회로 모델을 기반으로 배터리 팩 내부 발열량을 계산하고, 배터리 열 모델 구성을 위한 파라미터 추출 실험 방안을 제안하다. 또한, 전기자동차 방열 시스템의 영향 등으로 인한 발열량 변화를 실시간으로 보정하여 온도 모사 정확도를 개선한다. 열 모델링 기법의 유효성 검증을 위하여 전기자동차용 배터리 팩 기반의 시뮬레이션 및 실험을 진행한다.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.307-308
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• 2011

본 논문에서는 2차전지의 필수적인 충 방전 데이터의 수집 및 분석을 쉽게 할 수 있는 배터리 충 방전 데이터 수집 장치를 개발하였다. 개발된 장치는 데이터 샘플링 시간 설정(0.1~10초)과 충 방전 사이클 중 대기시간 설정이 가능하도록 설계하였다. 또한 충 방전 사이클 횟수를 배터리의 활성화와 전압 평균화를 위하여 최대 10회까지의 수행할 수 있도록 개발하였다. 개발된 장치의 성능을 검증하기 위해 LabVIEW로 측정된 데이터와 비교 분석하여 타당성을 검증하였다.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.311-312
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• 2011

본 논문에서는 납축전지의 충전 초기 전압변화를 이용한 축전지의 상태와 충전상태를 비교 평가하는 방법을 연구하였다. 12V/1.2Ah의 납축전지를 대상으로 NI사의 DAQ 장치로 충방전 실험 장치를 구축하고 LabVIEW로 프로그램을 작성하여 축전지의 전압과 전류를 측정하였다. 축전지가 노화된 경우 충전 초기 전압이 급격히 상승하였고, 충전 전류는 정상적인 축전지에 비해 상대적으로 적게 나타났다. 실험 결과를 바탕으로 축전지의 충전상태를 평가하였다.

• Journal of Information Processing Systems
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• v.6 no.2
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• pp.129-146
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• 2010

The trend of Next Generation Networks' (NGN) evolution is towards providing multiple and multimedia services to users through ubiquitous networks. The aim of IP Multimedia Subsystem (IMS) is to integrate mobile communication networks and computer networks. The IMS plays an important role in NGN services, which can be achieved by heterogeneous networks and different access technologies. IMS can be used to manage all service related issues such as Quality of Service (QoS), Charging, Access Control, User and Services Management. Nowadays, internet technology is changing with each passing day. New technologies yield new impact to IMS. In this paper, we perform a survey of IMS and discuss the different impacts of new technologies on IMS such as P2P, SCIM, Web Service and its security issues.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.544-546
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• 2008

An improved dual-path energy recovery circuit (ERC) using a current source and a voltage source for plasma display panel (PDP) is proposed. The proposed ERC uses the voltage source to charge a panel and the current source to discharge the panel. Thus, the proposed circuit can make the panel charge to $V_S$ and discharge to 0V, fully and it is possible to achieve zero voltage switching (ZVS) of all switches in H-bridge inverter and zero current switching (ZCS) of all switches in the ERC. Moreover, it has less conduction and switching loss in ERC devices by the dual energy recovery paths for charging and discharging the panel. Furthermore, it has features of canceling the gas discharge current, high performance and the low cost ERC components. The operation principle and features of the proposed ERC are presented in detail and verified with 42-inch SD PDP.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.9
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• pp.383-387
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• 2003

In this paper, we have studied about optimal transmission efficiency characteristics of pulse energy in a coal plant for removing environmental polluted gas. The electrical efficiency of pulse power systems depends on impedance of the reactor. To obtain high efficiency, we used MPC(Magnetic pulse compressor) as the power switch and tested their characteristics as electrode length of the reactor and charging voltage of capacitor, As results, we obtained a compressed pulse such as pulse voltage of 10㎸, rising time 200ns and pulse width of 500ns. With increasing electrode length, the load impedance was decreased but the electrical efficiency was increased.