• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.6
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• pp.1047-1054
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• 2007

This paper presents a high efficiency direct instantaneous torque control (DITC) of Switched Reluctance Motor(SRM) based on the nonlinear model. The DITC method can reduce the high inherent torque ripple of SRM drive system, but drive efficiency is somewhat low due to the high current and switching loss during commutations. In order to reduce a torque ripple, a fast torque reference trajectory is selected at every instantaneous rotor position. Based on the nonlinear model of SRM, the developing torque by one phase is fixed and the other phase is regulated for minimum switchings of phase switch and variation of torque. The switching during commutation can be reduced and fast commutation can be obtained in the proposed method. As a result, drive efficiency could be improved as well as torque ripple reduction. The validity of proposed method is verified by computer simulations and comparative experiments.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.247-249
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• 2008

There are many types of grid-connected inverter controllers; Synchronous Reference Frame (SRF)-based controller is the most popular methods. SRF-based controller is capable for reducing both of zero-steady state error and phase delay. However, SRF-based controller has a complex algorithm to apply in real application such as digital processor. Resonant controller is also reduced zero-steady state error, but its transfer function has a high order. In this paper, a simple proportional control is applied for grid connected inverter with LCL filter. LCL filter is a third order system. Applying a simple proportional controller is not increased the order of closed loop transfer function. By this technique, the single phase model is easily obtained. To reduce steady state error, proportional gain is set as high as possible, but it may produce instability. To compromise between a minimum steady state error and stability, the single phase model is evaluate through Root Locus and Bode diagram. PSIM simulation is used to verify the analysis.

• Journal of Power Electronics
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• v.14 no.4
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• pp.678-686
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• 2014

A novel auxiliary resonant commutated pole (ARCP) link for three-phase PWM voltage-fed converter is presented. The ARCP link consists of two auxiliary switches, one resonant inductance, and six diodes, which is simpler than the conventional ARCP designs. Based on the phase and amplitude control, the proposed converter can take a minimum switching times PWM method, which results in reduced losses and a simplified control. In addition, the zero-voltage resonance modes are analyzed. Finally, simulation and experimental results show that the system can realize zero-voltage switching with a unity power factor.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.495-497
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• 1994

Given the constraint of the AC input power factor and the DC-link voltage and current ripple in voltage source inverter, minimizing the size and cost of the DC-link fitter components is very important. This paper presents a procedure for the selection of DC-link filler element values in a three-phase PWM voltage source inverter-fed induction motor drive system, which can not only satisfy the requirements for the system performance but also minimize the filter size.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.11
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• pp.60-69
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• 1996

In this study, when the coherent detector has been developed and manufactured in the receiver of radar system, we have suggested and realized the 'Frequecny-Feedback correction (FFC)' that extracts its errors affecting the performance of radar, such as amplitude imbalances (k), phase imbalance ($\varphi$) between channels and offset votlages and corrects them to improve radar performances. Applying the FFC proposed, we analyzed sthe properties of the coherent detector and compared its perfomances after and before correction procdure. After the correction sequence, the amplitude imbalance was improved upt o 2dB and the phase imbalance over 9$^{\circ}$. The image rejection ratio (IRR), one of the figures of merit of radar system, was made better above 9 dB after correcting the coherent detector which possessed 23 dB before.

• Proceedings of the KIEE Conference
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• 1997.07b
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• pp.418-421
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• 1997

A control synthesis scheme is presented for nonlinear single-input-single-output (SISO) systems with parametric uncertainty which have completely unstable zero dynamics. The approach involves the derivation of an input-output linearizing control law which achieves internal stability for a nonlinear minimum phase approximation to the original system using Fliess normal form. A vector of unknown constant parameters is also considered. A Lyapunov-based additional control law is shown to stabilize the full system.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.7
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• pp.997-1004
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• 1990

In this paper, a design method of a robust adaptive regulator with feedfoward path based on the explicit criterion minimization is proposed. The convergence speed of parameter estimation is improved by using the stochastic Newton minimization method in the criterion minimization algorithm, and sensitivity derivatives are used in the regulator calculation for improving the robustness of the control system. Trh proposed adaptive regulator is applied to the stable minimum-phase and nonminimum-phase system, the results are shown that control performance and disturbance compensation ability of the regulator are improved. And the choosing method of input penalty is proposed.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.7 no.4
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• pp.51-58
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• 1993

This paper proposed a minmum time control method by a parabolic switching function to high speed position control, with high accuracy, of a Linear OC Motor A proposed method is organized simply and a bang-bang control's signal switched on a parabola type switching function in the phase for a minimum time control realization. However, a sliding mode occurs owing to system's modelling errors, so the minimum time control is realized a once switching bang-bang control by repeating trial experiments. Next time, in a neighborhood of the origin in the phase plane, a Linear OC Motor is stopped at the origin by the linear feedback control.

• Applied Chemistry for Engineering
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• v.4 no.3
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• pp.537-543
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• 1993

The effect of agitation on liquid-liquid dispersion was investigated in an immisible liquid phase(n-hexane/water) system. Four different types of six-bladed turbine impellers were used: a flat blade, two screen blades and a solid edged 60 mesh screen blade. We found that the extent of dispersion of organic phase and power consumption of agitator were decreased in the order of flat, solid edged, 60 mesh, and 40 mesh blades at same agitation speed. And the minimum agitation speed for complete dispersion of organic phase was increased with increasing volume fraction of organic phase. Also, mean diameter of liquid droplets of dispersed phase was decreased with increasing agitation speed and it was increased in the order of solid edged, flat, 60 mesh, and 40 mesh screen blades at same agitation speed. At complete dispersion, the minimum power consumption was not vary significantly with impeller blade types, but the solid edged screen blade impeller gave the smallest and uniform sizes of liquid droplets, and it had a good performance for liquid-liquid dispersion. In this condition, Power number was not affected by Reynolds number and it was constant in turbulent flow region, and Sauter mean diameter($d_{32}$) of liquid droplets was expressed as a function of volume fraction of organic phase(${\phi}$) and Weber number($N_{We}$) as follows: $d_{32}/D=a(1+b{\phi})N_{We}{^{-0.6}}$.

• Journal of Energy Engineering
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• v.18 no.4
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• pp.258-263
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• 2009

Jet Loop Reactor(JLR), in which a two-phase nozzle is installed, is the new design technique for the treatment of high concentration wastewater by accelerating of oxygen contacting between substrate and surrounding bacteria. This numerical study of the two phase jet flow was conducted to find the optimum design of JLR. It was shown that there was a minimum velocity in the nozzle for continuous circulation of wastewater. The optimum location and the size of the draft tube for continuous circulation were examined. It was certain that the smaller the air size is, the more the effect of the mixing increases. The relation between the mixing effect and the turbulence was confirmed.