• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1991.10a
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• pp.80-83
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• 1991

The need of UPS (Uninterruptible Power Sup-ply) system is dramatically increasing with the increased use of computers, telecommunica-tion system, building automation system, and office automation system in office buildings. The consequence of the power failure is very disas trous in intelligent office buil-dings. Thus, the nucessity of large scale UPS system with generations of large scale UPS system with generator is increasing. In this study, the configurations of large scale UPS system are reviewed and analyzed. The design guide and technical considerations of high reliability system are presented.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.121.3-121
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• 2002

The HFC network is one of the most useful network for high-speed data communication. Optical node unit, Trunk branch amplifier, Tap-offs, and Uninterrupted power supplies (UPS) are in this network. Since power failures of the equipments in the network is crucial, UPS should be periodically monitored and controlled by the Host to prevent long power failures. This paper describes a UPS management system which is to monitor and control UPS to supply electric power to ONUs and TBAs in the network.

• Proceedings of the IEEK Conference
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• 2002.06e
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• pp.307-310
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• 2002

A design for the input filter and the output filter of a single-phase UPS system is proposed. And also, this paper describes a reduction of the DC voltage ripple of a single-phase UPS. The input power of proposed UPS fluctuates with twice frequency of the utility source, which causes DC voltage fluctuation. The reduction of the DC voltage fluctuation requires a large DC link capacitor. The proposed method uses a LC series resonant filter paralleled with a conventional smoothing capacitor. The effectiveness of the proposed method was confirmed by simulation results.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1991.10a
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• pp.220-224
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• 1991

Uninterruptible Power Supply(UPS) Systems are widely used in a varietyof fields as highly reliable power sources. This paper describes the operation and performance of an UPS using sinusoidal Pulse Width Modulation (PWM)techniques. A newly developed UPS adopted switching element -power TR, power MOSFET, IGBT- is introduced. Experimental results showed that sinusoidal PWM techniques have good features for UPS systems.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.544-545
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• 2012

본 논문에서는 3상 4선식 UPS 인버터에 대한 저항성 수하 제어 방식 병렬운전 알고리즘을 제안하고, PSIM 시뮬레이션을 통해서 제안된 병렬운전 알고리즘과 강인 전압제어기를 적용한 2병렬 UPS 인버터의 운전 결과를 제시한다. 3상 UPS 인버터 2대로 병렬운전 환경을 구축하였고, 주파수-전압 강하 방식의 저항성 수하 제어를 이용하여 저항 부하, 유도성 부하, 비선형 부하에 대한 전력분담을 확인하였다.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.362-363
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• 2019

비상발전기를 사용하여 무정전 시스템을 구성할 경우, 발전기 시스템이 정전을 인식하고 비상발전기의 기동하는 시간동안은 정전이 발생함으로 통상적으로 단주기 ESS와 결합한 UPS 시스템을 구축하게 된다. 이 경우 UPS 시스템 구축을 위한 ESS 시스템과 인버터에 대한 부담이 존재한다. 본 논문에서는 비상발전기와 엔진의 동력전달 부 사이에 플라이휠과 전자식 클러치에 의한 새로운 비상발전기 단독형 UPS 시스템을 제안한다.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.195-204
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• 2015

In this paper, the development of a cost-effective active power filter/uninterruptible power supply (APF/UPS) system with seamless mode transfer is described. The proposed scheme employs a pulse-width-modulation (PWM) voltage-source inverter and has two operational modes. First, when the source voltage is normal, the system operates as an APF, which compensates for the harmonics and power factor while boosting the DC-link voltage to be ready for the disturbance, without an additional DC charging circuit. A simple algorithm to detect the load current harmonics is also proposed. Second, when the source voltage is out of the normal range (owing to sag, swell, or outage), it operates a UPS, which controls the output voltage constantly by discharging the DC-link capacitor. Furthermore, a seamless transfer method for the single-phase inverter between the APF mode and the UPS mode is also proposed, in which an IGBT switch with diodes is used as a static bypass switch. Dissimilar to a conventional SCR switch, the IGBT switch can implement a seamless mode transfer. During the UPS operation, when the source voltage returns to the normal range, the system operates as an APF. The proposed system has good transient and steady-state response characteristics. The APF, charging circuit, and UPS systems are implemented in one inverter system. Finally, the validity of the proposed scheme is investigated with simulated and experimental results for a prototype APF/UPS system rated at 3 kVA.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.4
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• pp.341-349
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• 2004

A parallel operation of Uninterruptible Power Supply(UPS) systems is used to increase power capacity of the system or to secure higher reliability at critical loads. In the conventional parallel operation, the load-sharing control to maintain the current balance is the most important, since the load-sharing is very sensitive to discord between components of each module, amplitude/phase difference, line impedance, output LC filter, and so on. To solve these problems various control algorithms are researching. However, these methods cannot apply to the different ratings of UPS. In the case, master and slave control algorithm for parallel operation is adequate. However, if the UPS ratings are different, the value of passive filters L, C is different, and it affects the sharing of current. This paper presents general problems of conventional parallel operation systems, and control strategy for parallel operation with different ratings. The validity of the proposed control strategy is investigated through simulation and experiment in the parallel operation system with two 3-phase UPS systems.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.6
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• pp.589-600
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• 1999

Audible noise of UPS(uninterruptible power supply) with small rated [Xlwer is usually generattxl by the c cooling fan‘ For active noise control for radiated noise of UPS, it is adequate to apply multiple-channel F FXLMS algorithm based on Filten어 x LM~longrightarrow algorithm. In this paper, to reduce the audible noise of UPS‘ Its m noise characteristics of UPS are an띠yzed and active noise control by using 이ffiMOClVlultiple- Reference/ M Multiple-Output) FXLMS algorithm is perf‘onned. Also, noise reduction characteristics are shown by computer S simulation and experimental results.

• Journal of Digital Convergence
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• v.13 no.4
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• pp.311-317
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• 2015

It is important to analyze and offer specialized start-ups effect factors for collegians in order to systematically and successfully support technology-centered start-ups of collegians, whose social experience is insufficient. However, consistently changing start ups environmental analysis is difficult, which can be a problem, because technology-centered start-ups factor analysis is carried out depending on statistical package. This paper proposes an ATSA system that demonstrates effect factors on technology-centered start-ups decision making as a hierarchial structure by using AHP, inputs the effect factors to judgment matrix after pre-processing, calculates standardized values and weights, verifies consistency, and draws priorities through weights integration. It was confirmed that the ATSA system can efficiently support decision making for technology-centered start-ups by quantitatively analyzing qualitative factors through experiments by applying multi-criteria decision making to the analyses of start-ups founders' internal and external factors and various start-ups environments.