• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.2
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• pp.8-15
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• 2010

This paper proposes a robust high-gain observer design scheme for nonlinear systems and its stability is analyzed based on Lyapunov theory. It is assumed that their states are unmeasurable. The proposed high-gain observer has the integrator of the estimation error in dynamics. It improves the performance of high-gain observers and makes the proposed observer robust to noisy measurements, uncertainties and peaking phenomenon as well. Its stability is analyzed by the Lyapunov approach. In order to verify the effectiveness of the proposed scheme, it is applied to output feedback controllers and some comparative simulation result with the existed observer based output feedback controllers and state feedback controllers is given.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.5
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• pp.630-636
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• 2011

This paper is concerned with the stability analysis and stabilization for the Takagi-Sugeno(T-S) fuzzy systems with parametric uncertainties. To reduce conservativeness in stability analysis for T-S fuzzy systems, fuzzy Lyapunov functions are used. Stability analysis is performed and robust fuzzy controller is designed for stabilization of the system with parametric uncertainties. The stability and stabilization conditions are formulated in terms of linear matrix inequalities (LMIs). Finally, simulation example is presented to show the effectiveness of the proposed approach.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.131-134
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• 2003

In this paper, we consider the problem of finding the stability region in state space for uncertain linear systems with input saturation. For stability analysis, two Lyapunov functions are chosen. One is for the lineal region and the other is for the saturated legion. Piecewise Lyapunov functions are obtained by solving successive linear matrix inequalites(LMIs) relaxations. A sufficient condition for robust stability is derived in the form of stability region of initial conditions. A numerical example shows the effectiveness of the proposed method.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.382-385
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• 1999

In this paper, by means of Lyapunov second method, the stability of IPD control servo systems is analyzed in the time domain for the first time. Based on the results of the stability analysis, the design rule to select the gain of IPD control is suggested such that the maximum error of output to the nominal system is guaranteed for all uncertainty and load variations. An example of a position control of a brushless dc motor is given to prove the unusefulness of the gain design rule.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.1
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• pp.46-51
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• 1987

Using the computer-generated Lyapunov functions due to Brayton-tong's constructive algorithm, we estimate the domains of attraction of dynamical systems of the second order, and analyze the asymptotic stability of large scale contincous-time and discrete-time systems by the decomposition and aggregation method. With this approach we get the less conservative stability results than the existing methods.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.6
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• pp.942-947
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• 1987

In this paper, we suggest a new adaptive control theory for discrete-time single-input single output systems based on the Lyapunov's stability theory by using the fact that the transfer function of the model is strictly positive real. And also, obervers are used in the structure of controller. The result of computer simulation shows that the proposed algorithm can be applied to both stable and unstable plants.

• Journal of Korean Institute of Industrial Engineers
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• v.22 no.1
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• pp.65-82
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• 1996

This paper proposes a sequential procedure which can be used to determine a truncation point and run length to reduce or remove bias owing to artificial startup conditions in simulations aimed at estimating steady-state behavior. It is based on the idea of Lyapunov exponent in chaos theory. The performance measures considered are relative bias, coverage, estimated relative half-width of the confidence interval, and mean amount of deleted data.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.70-74
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• 1998

In this paper, by means of Lyapunov second method, we analyze the stability of IP control servo systems in the time domain for the first time. Based on the results on the stability analysis, the design rule to select the gain of IP control is suggested such that the maximum error of output to the nominal system is guaranteed for all uncertainty and load variations. An example of a speed control of brushless dc motor given to prove the unusefulness of the gain design rule.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.620-624
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• 2011

This paper propose a new delay-dependent stability criterion of neutral time-delay systems. By employing double-integral terms in augmented states and constructing a new Lyapunov-Krasovskii's functional, a delay-dependent stability criterion is established in terms of Linear Matrix Inequality. Through numerical examples, the validity and improvement results obtained by applying the proposed stability criterion will be shown.

• 전기의세계
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• v.36 no.1
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• pp.14-20
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• 1987