• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.1993-1995
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• 2001

The subject of nonlinear control is an important area of automatic control. The behavior of nonlinear systems is much more complex. If the operating range of a control system is small, and if the involved nonlinearities are smooth, then the control system may be resonably approximated by a set of linear differential equations. This paper presents the deadbeat response attribute of some nonlinear systems, e.g., magnetic levitation, pendulum, van der pol oscillator etc.. The studied results through the computer simulation are shown a promising attribute of deadbeat response that the outputs of the systems are reached relatively fast the steady state.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.5
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• pp.827-837
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• 1994

This paper presents robustness propertis of the Kalman Fiter and the associated LQG/LTR method for linear time-invariant output-delayed systems. It is shown that, even for minimum phase plants, the LQG/LTR method can not recover the target loop transfer function. Instead, an upper bound on the recovery error is obtained using an upper bound of the solution of the Kalman filter Riccati equations. Finally, some dual properties between output-delayed systems and input-delayed systems are exploited.

• Advances in nano research
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• v.15 no.3
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• pp.215-224
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• 2023

Nonlinearity plays an important role in control systems and the application of design. For this reason, in addition to linear vibrations, nonlinear vibrations of the stepped nanobeam are also discussed in this manuscript. This study investigated the vibrations of stepped nanobeams according to Eringen's nonlocal elasticity theory. Eringen's nonlocal elasticity theory was used to capture the nanoscale effect. The nanoscale stepped Euler Bernoulli beam is considered. The equations of motion representing the motion of the beam are found by Hamilton's principle. The equations were subjected to nondimensionalization to make them independent of the dimensions and physical structure of the material. The equations of motion were found using the multi-time scale method, which is one of the approximate solution methods, perturbation methods. The first section of the series obtained from the perturbation solution represents a linear problem. The linear problem's natural frequencies are found for the simple-simple boundary condition. The second-order part of the perturbation solution is the nonlinear terms and is used as corrections to the linear problem. The system's amplitude and phase modulation equations are found in the results part of the problem. Nonlinear frequency-amplitude, and external frequency-amplitude relationships are discussed. The location of the step, the radius ratios of the steps, and the changes of the small-scale parameter of the theory were investigated and their effects on nonlinear vibrations under simple-simple boundary conditions were observed by making comparisons. The results are presented via tables and graphs. The current beam model can assist in designing and fabricating integrated such as nano-sensors and nano-actuators.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.887-890
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• 1996

In this study, based on the assumption that the displacements of suspension systems under the external forces are very small, a linear form of elastokinametic equations in terms of infinitesimal displacements and joint reaction forces are derived. The equations can be applied to any form of suspensions once the type of kinematic joints and bushings are identified. The validity of the method is proved through the comparison of the results from the more complex solution offered by ADAMS

• Bulletin of the Korean Mathematical Society
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• v.46 no.3
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• pp.463-475
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• 2009

This paper deals with the regularity properties for a class of semilinear integrodifferential functional differential equations. It is shown the relation between the reachable set of the semilinear system and that of its corresponding linear system. We also show that the Lipschitz continuity and the uniform boundedness of the nonlinear term can be considerably weakened. Finally, a simple example to which our main result can be applied is given.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1202-1206
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• 2001

The paper presents the dynamic stability of a vertical cantilevered pipe conveying fluid and having translational linear spring supports. Real pipe systems may have some elastic hanger supports or other mechanical attached parts., which can be regarded as attached spring supports. Governing equations are derived by energy expressions, and numerical technique using Galerkin's method is applied to discretize the equations of small motion of the pipe. Effects of spring supports on the dynamic stability of a vertical cantilevered pipe conveying fluid are fully investigated for various locations and spring constants of elastic supports.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1504-1508
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• 1996

In this paper, we derive dynamic equation of helicopter and design controller based on variable structure system. It is difficult to control helicopter because it has non-linear coupling between input and output of system and is MIMO system. The design of control law is considered here using variable structure methodology giving the robustness to parameter variations and invariance to some subsets of external disturbance. However we derive dynamic equations of helicopter and design stabilizing variable structure controller. Also, simulation results are given in this paper.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.483-484
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• 2019

This paper proposes a harmonic state space (HSS) modeling of DC microgrid. In the HSS model, nonlinear equations for the switched circuit model are transformed into multiple linear equations. The simulation results have shown the HSS modeling is comparable with PSIM simulation.

• Journal of the Korean Mathematical Society
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• v.56 no.1
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• pp.127-147
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• 2019

In this paper we establish some new explicit solutions for impulsive linear fractional differential equations with impulses at fixed times, which provides a handy tool in deriving singular integral-sum inequalities and an impulsive fractional comparison principle. Thus we study the Mittag-Leffler stability of impulsive differential equations with the Caputo fractional derivative by using the impulsive fractional comparison principle and piecewise continuous functions of Lyapunov's method. Also, we give some examples to illustrate our results.

• Korean Journal of Mathematics
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• v.24 no.3
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• pp.447-467
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• 2016

We prove the existence of random attractors for the continuous random dynamical systems generated by stochastic damped plate equations with linear memory and additive white noise when the nonlinearity has a critically growing exponent.