• 전자공학회논문지S
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• 제35S권4호
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• pp.10-19
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• 1998

With the advent of high-speed networks, the increasingly stringent performance requeirements are being placed on the underlying switching systems. Under these circumstances, simulation methods for evaluating the performace of such a switch requires vast computational cost and accordingly the importance of anlytical methods increases. In general, the performance analysis of a switch architecture is also a very difficult task in that the conventional queueing system such as switching systems, which consists of a large numbe of queues which interact with each other in a fiarly complicated manner. To overcome these difficulties, most of the past research results assumed that multiple queues become decoupled as the switch size grows unboundely large, which enables the conventional queueing theory to be applied. In this apepr, w analyze a non-blocking space-division ATM swtich with input queueing, and prove analytically the pheonomenon that virtual queues formed by the head-of-line cells become decoupled as the switch size grows unboundedly large. We also establish various properties of the limiting queue size processes so obtained and compute the maximum throughput associated with ATM switches with input queueing.

• 대한전기학회논문지:전력기술부문A
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• 제49권11호
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• pp.531-535
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• 2000

A method to compute the reactive powers of the added buses by the decoupled UPFC model for the optimal voltage profile is presented, by which the voltage magnitudes of PQ buses can get closer to the reference value(usually one p.u.). The performance index for assessing how much the voltage magnitude is closer to the reference value is defined as the squared sum of the present voltage minus the reference voltage multiplied by the weighting number associated with the relative importance of the buses. Numerical example in a 10-unit 39-bus power system with 2 UPFC's shows that the performance index can be very much reduced by operating many UPFC's with the reactive powers for the optimal voltage profile proposed in this paper.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 B
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• pp.460-462
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• 1998

In this study, we deal with a multivariable system which its input and output are coupled. This study presents a method for designing a controller which allows a coupled system to be transformed to a decoupled system in a standard model adopting 2DOF controller. And Wiener-Hopf($H_2$) approach is used so that the designed controller can minimize given cost function.

• KIEE International Transactions on Power Engineering
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• 제12A권1호
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• pp.31-35
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• 2002

This paper presents a new operation scheme of UPFC to minimize both generation costs and active power losses in a normal operation state of power system. In a normal operation, cost minimization is a matter of primary concern among operating objectives. This paper considers two kinds of costs, generation costs and transmission losses. The total generation cost of active powers can be minimized by optimal power flow, and active power losses in the transmission system can be also minimized by power flow control of UPFC incorporated with minimization of generation costs. In order to determine amounts of active power reference of each UPFC required for the cost minimization, an iterative optimization algorithm based on the power flow calculation using the decoupled UPFC model is proposed. For verification of the proposed method, intensive studies have been performed on a 3-unit 6-bus system equipped with a UPFC.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.205-209
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• 2006

A linear motor based transfer vehicle is significantly focused as transportation systems in marine terminals for the future. We propose a control method for the systems to hence mass reduction and propulsion effects at a starting point by using a lift-force mechanism. This method is newly based on a combined levitation-and-propulsion power by a lift and thrust force of a permanent magnet linear synchronous motor (PMLSM), which is carried out by a decoupled control. We exam that our proposed control largely compensates the vehicle weight, reduces friction effect of the system, and increases its velocity. Consequently, this result contributes numerous productivity and economical efficiency for the port systems.

• 대한전기학회논문지
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• 제38권11호
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• pp.877-887
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• 1989

In this paper, we attempt to achieve high dynamic performance by means of decoupled control of rotor speed and flux. Recently developed nonlinear feedback control theories are utilized. The rotor fluxes are estimated based on the rotor circuit equations. When the estimation error of the rotor flux tends to zero, the rotor speed and flux dynamic characteristics of the induction motor with our controller become linear. To minimize the deterioration of control performance, we use an identification algorithm for the rotor resistance. We analyze the dynamic behavior of the closed loop system with our controller. Both simulation and experimental results are included to demonstrate the practical significance of our result. In particular, our experimental results show that recently developed nonlinear feedback control techniques are of practical use in control of induction motors.

• Journal of Power Electronics
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• 제14권3호
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• pp.608-620
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• 2014

In this paper, an adaptive neural phase-locked loop (AN-PLL) based on adaptive linear neuron is proposed for grid-connected doubly fed induction generator (DFIG) synchronization. The proposed AN-PLL architecture comprises three stages, namely, the frequency of polluted and distorted grid voltages is tracked online; the grid voltages are filtered, and the voltage vector amplitude is detected; the phase angle is estimated. First, the AN-PLL architecture is implemented and applied to a real three-phase power supply. Thereafter, the performances and robustness of the new AN-PLL under voltage sag and two-phase faults are compared with those of conventional PLL. Finally, an application of the suggested AN-PLL in the grid-connected DFIG-decoupled control strategy is conducted. Experimental results prove the good performances of the new AN-PLL in grid-connected DFIG synchronization.

• Journal of Electrical Engineering and Technology
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• 제9권3호
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• pp.899-907
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• 2014

This paper deals with fault-tolerant control of five-phase induction motor (IM) drives under single-phase open. By exploiting a decoupled model for five-phase IM under fault, the indirect field-oriented control ensures that electromagnetic torque oscillations are reduced by particular magnitude ratio currents. The control techniques are developed by the third harmonic current injection, in order to improve electromagnetic torque density. Furthermore, Proportional Resonant (PR) regulator is adopted to realize excellent current tracking performance in the phase frame, compared with Proportional Integral (PI) and hysteresis regulators. The analysis and experimental results confirm the validity of fault-tolerant control under single-phase open.

• 전력전자학회논문지
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• 제1권1호
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• pp.7-11
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• 1996

From the cost-effective point of view, it is very important to design a current with the highest utilization factor of current capacity of power devices. This can be accomplished by a current controller without overshoot irrespective of the varying bounds of control voltage in PWM converters and the dead time due to the time delay. This paper suggests a novel decoupled controller with Smith-Predictor which has the fast control response without overshoot and steady stats error and also deal with the design method of the controller for PWM converters. The extensive digital simulations done by SIMULINK/MATLAB show that the suggested controller guarantees the full utilization of current capacity of power devices and the decoupled current control behavior.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.404-408
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• 2005

Having flexibility in a manipulator will degrade trajectory tracking control and manipulator tip positioning. In practice, however, constraints imposed by various operating requirements, will render the presence of such flexibility unavoidable. The dynamic analysis of the flexible manipulator is essential in designing proper control systems. A flexible manipulator consists of infinite number of elastic modes and the modes are usually coupled to each other. For the practicality, however, it is usually assumed that the flexible system consists of finite number of elastic modes and the modes are decoupled. These assumptions result in a linear and decoupled mathematical model of the flexible manipulator and simplify the analysis of the dynamic behavior and the design of the control system. The decoupling and linearization of the flexible link, however, has been assumed without in depth analysis. This paper focuses on the analysis of the significance of the non-linear coupling factors.