• 대한전자공학회논문지
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• 제24권4호
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• pp.610-617
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• 1987

This thesis is concerned with fault-tolerance of a B-net (Beta-network) which is a kind of interconnection network in the multicomputer system. In this paper, a method for obtaining Maximal Tolerable Fault Set(MTFS) of link line connecting switching elements in the arbitrary B-net is presented. Using this method, it is seen that testing of DFA capability is possible when s-a-faults of link line occur, and criterion for determining degree of fault- tolerance of a B-net in terms of link line is introduced.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 추계학술대회 논문집
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• pp.71-72
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• 2016

전동기의 운전 영역을 확대하기 위해 부스트 컨버터를 이용하여 가변 DC link를 합성한다. 가변 DC link 구간에서는 스위칭 손실이 증가하기 때문에 스위칭 횟수를 줄이는 전략이 필요하다. 제안하는 Edge-Cutting Pulse Width Modulation(ECPWM)을 통해 스위칭 손실을 1/3로 절감하고, 최적의 고조파 특성을 갖는 직류단 전압의 크기를 결정한다. 이를 이용해 가변 직류단 전압 구간에서 인버터 손실을 감소시키며, Bolognani 과변조 방법을 적용해 안정적인 6-스텝으로의 절환까지 고려한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.129-131
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• 1993

Power conversion system of high performance requires high switching frequency power converter. In order to minimize commutation stress and switching losses, in this paper, AC-DC converter is embedded a partial resonant DC-Link circuit with the object of ZVCS(zero voltage switching and zero current switching). The partial resonant occurs just before converter switch operates. Thus, VA ratings of the elements and their dissipations due to effective series resistance (ESR) are very low. Some simulative results on computer are included to confirm the validity of the analytical results.

• ETRI Journal
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• 제42권1호
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• pp.17-25
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• 2020

Multiple-input multiple-output systems can achieve a full sum rate (SR) via full duplex (FD). However, its performance is degraded by self-interference (SI) that occurs between the transmitter and receiver at the same node and thus is constrained by error floors. Conversely, half duplex (HD) can avoid the SI albeit at lower spectral efficiency, and the slope of its error curve is determined by the diversity order. In this study, a link selection scheme based on switching between FD and HD is examined as a simple method to improve the bit error rate (BER) performance of FD systems. In the proposed link selection algorithm, either FD or HD is selected based on the received minimum distance and signal-to-interference plus noise ratio. Simulation results indicate that the proposed hybrid FD/HD switching system offers significant BER performance improvement when compared with that of the conventional FD and FD based on only the received minimum distance under the same fixed SR. Under relatively sufficient SI cancellation, it is demonstrated to outperform the HD with a diversity advantage in low and medium signal-to-noise ratio region.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제2B권3호
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• pp.133-139
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• 2002

In this paper, a prototype of an active auxiliary quasi-resonant DC link (QRDCL) snubber assisted voltage source bidirectional power converter (AC to DC and DC to AC) operating at zero voltage soft-switching (BVS) PWM nlode is presented for a Battery Energy Storage System (BESS). The operating principle of this QRDCL circuit and multifunctional control-based converter system, including PWM inverter mode in which energy flows from the battery bank to the three-phase utility-grid in addition to an active PWM converter mode in which energy flows from the utility-grid to the battery banks are described respectively by the control implementation on the basis of d-q coordinate plane transformation. The multifunctional operation characteristics of this three-phase ZVS PWM bi-directional converter with QRDCL is demonstrated fer a BESS under the power conditioning and processing schemes of energy supply mode and energy storage mode, and compared with a conventional three-phase hard switching PWM bi-directional converter for a BESS. The effectiveness of the three-phase ZVS PWM hi-directional converter with QRDCL is proven via the simulation analysis.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.280-284
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• 1997

In this paper, Nonlinear VSS control based on bang-bang control concept is derived under the assumption that the control input is bounded. We try to derive control algorithm which has almost same performance as the time optimal control. We focus this control scheme on the real implementation of DC motor position controller of flexible link, i.e. we obtain the switching curves from the real data of DC motor system operating under the full maximum and minimum applied voltages. State space is separated into several regions and we set different switching surfaces in each region to reduce chattering problem. The efficiency of the proposed controller is compared with PID controller and it is shown that the controller converges fast than PID controller without chattering. The hybrid controller scheme is also proposed not only to control the position of hub but also to reduce the vibration of end tip of flexible link.

• Journal of Power Electronics
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• 제16권4호
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• pp.1504-1512
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• 2016

This paper presents a new single-phase asymmetrical cascaded multilevel DC-link inverter. The proposed inverter comprises two stages. The main stage of the inverter consists of multiple similar cells, each of which is a half-bridge inverter consisting of two switches and a single DC source. All cells are connected in a cascaded manner with a fixed neutral point. The DC source values are not made equal to increase the performance of the inverter. The second circuit is a folded cascaded H-bridge circuit operating at a line frequency. One of the main advantages of this proposed topology is that it is a modular type and can thus be extended to high stages without changing the configuration of the main stage circuit. Two control schemes, namely, low switching with selective harmonic elimination and sinusoidal pulse width modulation, are employed to validate the proposed topology. The detailed approach of each control scheme and switching pulses are discussed in detail. A 150W prototype of the proposed system is implemented in the laboratory to verify the validity of the proposed topology.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.544-547
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• 1989

The introduction of resonant link inverters has allowed the use of much higher switching frequencies in induction motor current regulators. The resonant link inverter,however, requries the use of discrete time switching strategies. This type of controller,while giving the best possible performance, is difficult to implement, since motor parameters must be calculated or measured. The delta modulated current regurator (DMCR) has been introduced as a controller without additional state feedback. A discrete pulse modulated current regulator which controls load current is introduced in the paper.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권1호
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• pp.50-67
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• 2015

The Cognitive Radio (CR) paradigm in tactical ad hoc networks is an important element of future military communications for network-centric warfare. This paper presents a novel Cognitive Link State Routing protocol for CR-based tactical ad hoc networks. The proposed scheme provides prompt and reliable routes for Primary User (PU) activity through procedures that incorporate two main functions: PU-aware power adaptation and channel switching. For the PU-aware power adaptation, closer multipoint relay nodes are selected to prevent network partition and ensure successful PU communication. The PU-aware channel switching is proactively conducted using control messages to switch to a new available channel based on a common channel list. Our simulation study based on the ns-3 simulator demonstrates that the proposed routing scheme delivers significantly improved performance in terms of average end-to-end delay, jitter, and packet delivery ratio.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1364-1367
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• 2005

In this paper, a novel prototype topology of soft switching PWM controlled high frequency AC power conversion circuit without DC voltage smoothing chemical capacitor filter link from the voltage grid of utility frequency AC power supply source with 60Hz-100V or 60Hz-200V is proposed and introduced for innovative consumer induction heating(IH) boiler applications as hot water producer, steamer and super heated vapor steamer.