• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.2
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• pp.261-269
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• 2018

In this paper, we propose a Takagi-Sugeno (T-S) fuzzy-model-based design for the tracking control of a class of nonlinear underwater glider. By using the partial linearization and the sector nonlinearity, the underwater glider with six degrees of freedom (6 DOF) is modelled by the T-S fuzzy model. The concerned tracking control problem with $H_{\infty}$ performance is converted into the stabilization one for the error dynamics between the given nonlinear underwater glider and the reference time-varying input. Sufficient conditions are derived for the asymptotic stabilizability of the error dynamics in the format of matrix inequality. Simulation results demonstrate the effectiveness of the proposed design methodology.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.406-410
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• 2004

Generally, a voltage difference exists between the reference and the output voltagesin a pulse width modulated (PWM) voltage source inverter (VSI). In this paper, the nonlinearity in a PWM VSI is analyzed and a new on-line estimation method in consideration of parameter variations for a permanent magnet synchronous motor (PMSM) is proposed to compensate the time varying voltage distortion.

• Journal of Veterinary Clinics
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• v.35 no.2
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• pp.67-69
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• 2018

Three dogs were referred for emergency care after fall accidents. All cases showed hyperglycemia at initial testing, with no history of diabetes mellitus. After varying periods of time, the blood glucose levels in all cases returned to within the reference range. The present report describes three cases of typical trauma-associated hyperglycemia in dogs.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.427-431
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• 1996

The MRAS proposed by Schauder [8] is modified to improve robustness to the change of load torque and/or the variation of the stator resistance. The difference between the voltage and the current model is fed into the current model via proportional and integral gains. In order to generalize the MRAS, supposing that the rotor speed is time varying, we add a compensating term to the current model. It does not alter the Popov's integral inequality condition. Also, the asymptotic stability of the modified MRAS (MMRAS) is shown with the stability proof technique as in the original paper. By the simulation works, it is verified that the MMRAS obtains improved performance than the original MRAS.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.323-326
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• 1996

In a simple system, the control schemes work well provided that the characteristic of the plant or the coefficients are known and fixed. But the condition is not met in the system like satellite, for example, varying over time and the coefficients of dynamic system change due to disturbance, etc, and the better precise model is required to control the given dynamic system well. Conversely, the fixed controller make the unmodel dynamic system with a wide class of modelling error be stable within the error tolerance limits. Also, a robust model reference adaptive control scheme is designed for the plant, paying attention to the derivation of the appropriate parametric model and the design of the normalizing signal to guarantee that it has the desired properties.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.625-633
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• 2006

Spatial variability of ground motions has significant influence on dynamic response of longitudinal structures such as bridges and tunnels. The coherency function, which quantifies the degree of positive or negative correlation between two ground motions, is often used to describe the spatially variable ground motions. This paper compares two available procedures for developing spatially variable ground time histories from a given coherency function. Hao's method shows serious limitation, resulting in unrealistic decrease in coherency with increase in distance Abrahamason's method, on the other hand, preserves important characteristics of the reference ground motion. Therefore, the Abrahamason's method is recommended to be used in developing spatially varying ground motions.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.6
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• pp.342-350
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• 2003

In this paper, a levitation controller for a magnetic levitation(MagLev) system is designed and implemented. The target to be controlled is PEM(permanent and electromagnet) type with 4-corners levitation which is open-loop unstable, highly non-linear and time-varying system. The digital control system consists of a VME-based CPU board, AD board, PU board, 4-Quadrant chopper, and gap sensor, accelerometer as feedback sensors. In order to estimate the velocity of the magnet, we used 2nd-order state observer with acceleration and gap signal as input and output, respectively. Using the estimated states, a state feedback control law for the plant is designed and the feedback gains are selected by using the pole-placement method. The designed controller is experimentally validated by step-type gap reference change and force disturbance test.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.6
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• pp.705-713
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• 1999

In this paper, we propose a new motion and force control methodology for constrained robots as an approach of hybrid discrete-continuous dynamical system. The hybrid dynamic system modeling of robotic manipulation tasks with constraints is presented, and the hybrid system control architecture for unconstrained and constrained motion system with parametric uncertainties is synthesized. The optimal reference stiffness of robot manipulator is generated by the hybrid automata as a discrete state system and the control behavior of constrained system which has poor modeling information and time-varying constraint function is improved by the constrained robots as a continuous state system. The performance of the proposed constrained motion control system is successfully evaluated via experimental studies to the constraint tasks.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.5
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• pp.31-36
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• 1983

The indirect M.R.A.C. method using the W.L.S. algorithm is applied to the speed control of a D.C. motor on the assumption that the motor is the 1-st order, completely controllable and observable, non-minimum phase plant. By the help of M6809 microprocessor system the experiments are performed with respect to the sinusoidal and square reference input. The results show that the speed of a D.C. motor is well controlled by the indirect M.R.A.C. method using W.L.S, algorithm, and that the W.L.S. algorithm is quite suitable to the time-varying plant.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.70-72
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• 2007

In this study, electromagnetic fields emitted from the various environment in the hospital were measured. Measurement spot was patients' head. To monitor how much magnetic fields are emitting from operation room, monitoring device was attached to 19 anesthesiologist and monitoring lasted 8 hours. We also took a measurement from various medical devices. Devices include ESWL, PET, MRI, CT, Gamma knife, X-ray, Angiogram, Echocardiogram, Upper GI and Linear Accelerator. Electromagnetic fields were measured from 10 spots from each of 5 patient waiting room. As a results, there were no places showing risk of high exposure. All the measurement values were below the reference levels for general public exposure to time varying electric and magnetic fields which is issued by ICNIRP.