• Journal of Digital Contents Society
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• v.4 no.2
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• pp.139-146
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• 2003

This paper explains the design and implementation of the ERA(Error Recovery Agent). ERA is a system that is suitable for detecting, sharing and recovering software error based on multimedia distance education system. This system consists of an ED, ES, and ER. ED detects an error by hooking techniques. ES is an agent which is an error sharing system for distributed multimedia distance education system. We propose how an error application can be treated and recovered as 'media' in a multimedia collaborative environment.

• Journal of the Korea Society of Computer and Information
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• v.21 no.6
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• pp.1-7
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• 2016

An uninterruptible power supply (UPS) allows small companies and domestic users to cope with power outages; but existing designs lack flexibility of control and require expensive battery maintenance, with a cost proportional to the outage compensation time. We combine a compact synchronous generator with a battery, with 10% of the capacity that would otherwise be required, to obtain a UPS with reduced maintenance costs for the same performance. Any UPS must respond immediately to a power loss, and our uninterruptible generator supply (UGS) is therefore built around real-time scheduling of its internal operations; this also makes it suitable for integration into the industrial gateway. The UGS is based on a real-time operating system, with an integrated wireless module providing connectivity to a web server, for monitoring and management, which can be performed remotely on a mobile device.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.781-784
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• 1993

Most linguistic models of processes or plants known are essentially static, that is, time is not a parameter in describing the behavior of the object's model. In this paper we show two models for synchronous finite state machines (FSM) based on fuzzy logic, namely the Crisp-State-Fuzzy-Output (CSFO FSM) and Fuzzy-State-Fuzzy Output (FSFO FSM). As a result of the introduction of the FSM models, the improved architectures for fuzzy logic controller have been defined. These architectures featuring pipelined intelligent fuzzy controller are discussed in terms of dimensionality of the model. VLSI integrated circuit implementation issues of the fuzzy logic controller are also considered. The presented approach can be utilized for fuzzy controller hardware accelerators intended to work in the real-time environment.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.5
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• pp.524-530
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• 1999

This paper describes performance analysis techniques for SSSC using computer simulations with EMPT and experiments with a hardware scaled-model. A switching-level simulation model with EMTP was developed for the SSSC connected in series with the transmission line. The increase of transmission capability and dynamic performance was analyzed with the simulation model. The simulation results were reverified by experimental works with a hardware scaled-model. The developed analysis techniques can be used for designing and evaluating actual system of SSSC.

• Proceedings of the KIEE Conference
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• 2007.04b
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• pp.134-137
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• 2007

LMTT(Linear Motor-based Transfer Technology) 시스템은 항만 컨테이너 이송장치의 자동화 시템으로 기술적 포화상태에 이른 AGV (Automated Guided Vehicle)의 대체 수단으로 제안되었다. 본 논문에서는 PMLSM (Permanent Magnetic Linear Synchronous Motor)을 기본 구조로 한 LMTT에서 발생할 수 있는 레일과 차체간의 인척력 변화와 다양한 부하 중량에 대한 시스템 내부 변수의 변동에 적응할 수 있는 제어기 설계에 초점을 두었다. 그렇게 됨으로써 제어시 큰 방해요소로 작용하는 마찰력에 의한 백래쉬 및 데드존을 최소화하여 속응성 및 정밀도를 향상시키고자 하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.1 no.2
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• pp.193-197
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• 1997

In this paper, we propose a new PN chip clock generator which employs two synchronous counters to achieve precise phase control of chip clock. In a CDMA code acquisition and tracking system, the PN chip clock is required to operate highly reliable without any glitch even under harsh environment condition such as temperature and voltage fluctu-aliens. The digital implementation of the proposed PN chip clock generator imparts it with much desired reliability. Since the proposed chip clock generator can be easily controlled into one of the states: free running, phase advance, and delay state, it can be applied to data processing as well as code synchronization. We have done FPGA implementation of the proposed logic and have verified its satisfactory operation up to 50 MHz.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.1
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• pp.91-100
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• 2002

This paper deals with the ripple reduction of the electromagnetic torque developed in IPMSM(Interior Permanent Magnet Synchronous Motor). Generally, torque ripple is an important causes of vibration and noise of motor. For reducing torque ripple in IPM with nonsinusoidal EMF, the optimal current which is able to control maximum torque/ampere is considered to be introduced In the proposed method. The fact of torque ripple being reduced when the optimal current Is used in motor is verified through simulation and experiment.

• Proceedings of the KIEE Conference
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• summer
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• pp.1319-1321
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• 2004

This paper presents a model and simulation for the korean type multi-propulsion system consisting of a gas turbine driven synchronous alternator coupled to a rectifier and dc-to-dc converter. The simulation modules include turbine system, alternator and rectifier, dc-to-dc converter, power management module. A modular, system level simulation of the propulsion system prototype is presented in order to confirm stability for loads with uncertain input impedances and uncertain control loop speeds.

• Proceedings of the KIEE Conference
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• summer
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• pp.1103-1105
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• 2004

현대 도시인들에게 전력의 신뢰성있는 공급은 당연시되고 있다. 그러나, 2002년 캘리포니아에서 있었던 대규모의 정전 사고는 불안정한 전력의 공급이 현대 문명 생활에 있어서 얼마나 큰 영향을 끼치며, 개별적인 보완 전력 공급의 중요성에 대해서 일깨워주는 계기가 되었다. 지금까지 이러한 전력 공급의 중단에 대한 주요 대비책으로서 비상용 엔진 발전기 시스템은 보조 전원의 중요한 역할을 해왔다. 여기에서 더 높은 효율과, 첨두 부하 절감의 기능, 그리고 전력 계통과의 Co-generation 기능을 가지는 고기능의 제어 시스템에 대한 수요가 증대되어지고 있는 상태이다. 본 논문에서는 다수 비상용 발전기들의 병렬 운전 및 전력 계통과의 연계 운전을 지원하는 고기능의 디지털 전력제어 시스템과 운전 지원을 위한 감시 제어 시스템에 대해 소개한다.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.3
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• pp.134-145
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• 2004

This paper presents and analyses protection schemes for a series active compensator, which consists of a Unified Power Quality Conditioner (UPQC) or a hybrid active power filter. The proposed series active compensator operates as a high impedance "k(D)" for the fundamental components of the power frequency during over current conditions in the distribution system. Two control strategies are proposed in this paper. The first strategy detects the fundamental source current using the p-q theory. The second strategy detects the fundamental component of the load current in the Synchronous Reference Frame (SRF). When over currents occur in the power distribution system momentarily, the proposed schemes protect the series active compensator without the need for additional protection circuits, and achieves excellent transient response. The validity of the proposed protection schemes is investigated through simulation and compared with experimental results using a hybrid active power filter systems.