• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.12a
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• pp.113-117
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• 2002

PID controllers, which have been widely used in industry, have a simple structure and robustness to modeling error. But it is difficult to have uniformly good control performance in system parameters variation or different velocity command. In this paper, we propose a nonlinear adaptive PR controller based on an Immune feedback mechanism and a gradient descent teaming. This algorithm has a simple structure and robustness to system parameters variation. To verify performances of the proposed nonlinear adaptive PID controller, the speed control of nonlinear DC motor Is peformed. The simulation results show that the proposed control systems are effective in tracking a command velocity under system parameters variation

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2003.06a
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• pp.141-144
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• 2003

This paper proposes a design method of a CDBC(Continuous-time Deadbeat Controller)system that takes into account the response between the sampling instant and using second-order smoothing elements. The continuous deadbeat controller is composed of a serial integral compensator and a local feedback compensator introduced into the state feedback loop. A DC servo motor is chosen for implementing CDBC algorithm. Especially according to the variable input and disturbance, corresponding CDBC design method is suggested. A Matlab Simulink is used for simulation with the Motor parameter. By computer simulations, control inputs and system outputs are shown to have desirable property such as smoothness.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.8
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• pp.1400-1406
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• 2016

This paper presents a new adaptive converter control approach for electric motor systems whose voltage source is excited from photovoltaic (PV) power generators. First, an electric model is represented with dynamic states and output velocity of such DC motor systems. We propose a hybrid converter control law in which a state feedback control is applied as an auxiliary control framework. Moreover, control parameter estimation is derived to realize adaptive converter systems for effective control performance against stochastic PV power excitation in practice. We carry out stability analysis for such converter system by using a well-known eigenvalue theory. Lastly, numerical simulation is conducted to test reliability of the proposed converter control approach and prove its superiority in the control point of view.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.308-310
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• 1995

Most of the elevator door controllers have been controlled by DC Motors as an actuator. Recently, The control system using AC induction motor and general purpose inverter has been applied to control of elevator door. But there are some difficulties in making use of this system, such as adjustment of door speed pattern, door open-close time, and security of passenger safety. In order to solve these problems, a special inverter has, been developed with an encoder feedback. From the result of field-test, we proved that a special inverter with encoder feedback device has come to considerable effect. Until now about 1,200 sets of these inverters are operated in Korea and about 100 sets are operated in South-east Asia.

• Journal of electromagnetic engineering and science
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• v.3 no.2
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• pp.118-125
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• 2003

This paper presents a 5.8-㎓ oscillator that uses a novel defected ground structure(DGS), which is etched on the metallic ground plane. As the suggested defected ground structure is the structure for mounting an active device, it is the roles of a feedback loop inducing a negative resistance as well as a frequency-selective circuit. Applying the feedback loop between the drain and the gate of a FET device produces precise phase conversion in the feedback loop. The equivalent circuit parameters of the DGS are extracted by using a three-dimensional EM simulation ,md simple circuit analysis method. In order to demonstrate a new DGS oscillator, we designed the oscillator at 5.8-㎓. The experimental results show 4.17 ㏈m output power with over 22 % dc-to-RF power efficiency and - 85.8 ㏈c/Hz phase noise at 100 KHz offset from the fundamental carrier at 5.81 ㎓.

• Journal of Drive and Control
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• v.13 no.3
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• pp.15-23
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• 2016

The direct-drive servo valve(DDV) is a kind of one-stage valve because the main spool valve is directly driven by the dc motor. Since the DDV structure is simple, it is less expensive, more reliable, and offers a reduced internal leakage and a reduced sensitivity to fluid contamination. The control system of the DDV is highly nonlinear due to a current limiter, a voltage limiter, and the flow-force effect on the spool motion. The shape of the step response of the DDV-control system varies considerably according to the magnitudes of the step input and the load pressure. The system-design requirements mean that the overshoots should be less than 20%, and the errors at 0.02s should be less than 2%, regardless of the reference-step input sizes of 1V and 5V and the load-pressure magnitudes of 0MPa and 20.7MPa. To satisfy the system-design requirements, the PID-controller parameters of $K_c$, $T_i$ and $T_d$, and the derivative-feedback gain of $K_{der}$ are designed using the root locus and manual tuning.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.2
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• pp.99-108
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• 2018

This paper presents a design study of a solid state power oscillator to replace the conventional magnetron. The operational conditions of a single-stage 300 W LDMOS power amplifier were fully characterized. The power module consisted of two amplifiers connected in parallel. A delay-line feedback loop was designed for self-oscillation. A phase shifter was inserted in the delay-line feedback loop for adjusting the round-trip phase. Experiments performed using the power oscillator showed an output power of 800 W and a DC-RF conversion efficiency of 58 % at 2.327 GHz. The measured results were in good agreement with those predicted by numerical simulations.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1027-1030
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• 1996

The purpose of this study was to develop systematic diagnostic system testing easily, rapidly vestibular function of patients suffered from vestibular syndrome such as nausea vomiting, dizzness, ataxia. Diagnostic system composed of rotatory chair system which rotated sinusoidally patients against their vertical axis for purpose of invoking eye movement by vestibulo-ocular reflex and the softwares which storaged eye movement into computer and analyzed eye movement. Rotatory chair system consisted of comfortable chair and DC servomotor with reducer(1:80) by controlled servo in field of nonlinear motor control, double feedback loops system containing velocity feedback loop and position feedback loop was applied to this sever controlled rotatory chair system. Maximum rotatory velocity of rotatory chair was upto 60 degree per second and frequency range was 0.01 to 0.64 Hz. These above results suggest that clinical rotatory chair system may test easily, rapidly vestibular function and diagnose etiology of dizziness, thus giving effective assistance on the treatment of dizziness patients.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.2
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• pp.131-138
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• 2007

In this paper, a novel nonlinear control method of the CVCF(constant voltage and constant frequency) output voltage for the three-phase PWM inverter with LC output filters is proposed. A nonlinear modeling including the output LC filters is linearized by feedback linearization theory, the controllers of which can be designed based on a linear control theory. It is applied to the DC/AC power conversion of the PWM inverter for stand-alone wind power generation system. It has been verified by the experimental results that the proposed control scheme gives high dynamic responses at load variation as well as a zero steady-state error.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.2
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• pp.79-84
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• 2015

Voltage sags are considered the dominant disturbances affecting power quality. Dynamic voltage restorers(DVRs) are mainly used to protect sensitive loads from the electrical network voltage disturbances such as sags or swells and could be used to reduce harmonic distortion of ac voltages. The typical DVR topology essentially contains a PWM inverter with LC Filter, an injection transformer connected between the ac voltage line and the sensitive load, and a DC energy storage device. For injecting series voltage, the PWM inverter is used and the passive filter consist of inductor(L) and capacitor(C) for harmonics elimination of the inverter. However there are voltage pulsation responses by the characteristic of the LC passive filter that eliminate the harmonics of the PWM output waveform of the inverter. Therefore, this paper presented design and feedback performance of LC filter used in the DVRs. The voltage control by LC filter should be connected in the line side since this feedback method allows a relatively faster dynamic response, enabling the elimination of voltage notches or spikes in the beginning and in the end of sags and strong load voltage THD reduction. Illustrative examples are also included.