• Honam Mathematical Journal
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• v.8 no.1
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• pp.21-49
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• 1986

A class of singular quadratic control problem is considered. The state is governed by a higher order system of ordinary linear differential equations and very general nonstandard boundary conditions. These conditions in many important cases reduce to standard boundary conditions and because of the conditions the usual controllability condition is not needed. In the special case where the coefficient matrix of the control variable in the cost functional is a time-independent singular matrix, the corresponding optimal control law as well as the optimal controller are computed. The method of investigation is based on the theory of least-squares solutions of multi-valued operator equations.

• Proceedings of the Korean Society for Quality Management Conference
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• 2006.04a
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• pp.313-318
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• 2006

Many control charting methods for both i.i.d and autocorrelated data can be viewed as charting the output of a linear filter applied to the process data. We propose a generalization of this concept, in which the filter parameters are optimally selected to minimize the out-of-control ARL while constraining the in-control ARL to some desired value. A number of interesting characteristics of the optimal fitters are discussed.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.83-87
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• 1999

The purpose of this study is to provide the new method for selection of a close to optimal scalar control of linear time-periodic system. The case of scalar control is considered, the gain matrix being assumed to be at worst periodic with the system period T. The form of gain matrix may have various kinds but must have same period, for example, one of each element being represented by Fourier series. As the optimal gain matrix I consider the matrix ensuring the minimum value of the larger real part of the Poincare exponents of the system. Finally we present a pole placement algorithm to make the given system be stable. It is possible to determine the stability of the given periodic system without get the analytic solution. The application of the method does not require the construction of the Floquet solution. At present state of determination of the gain matrix for this case will be done only by systematic numerical search procedures.

• Journal of Power System Engineering
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• v.12 no.1
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• pp.72-79
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• 2008

This paper designs a looper-tension controller for mass-flow stabilization in hot strip finishing mills. By Newton's 2nd law and Hooke's law, nonlinear dynamic equations on the looper-tension system are firstly derived, and linearized by a linearization algorithm using a Taylor's series expansion. Moreover, a tension calculation model is obtained from the nonlinear dynamic equations which is called as a soft sensor of strip tension between two neighboring stands. Next, a looper-tension servo controller is designed by an ILQ(Inverse Linear Quadratic optimal control) algorithm, and it is combined with a minimal disturbance observer which to attenuate speed disturbances by AGC and operator interventions, etc.. Finally, it is shown from by a computer simulation that the proposed ILQ controller with a disturbance observer is very effective in stabilizing the strip mass-flow under some disturbances, moreover it has a good command following performance.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1839-1844
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• 1991

For a single-input nonlinear system, the transformation which transposes the nonlinear system to a controllable-like canonical system has been proposed. However this method islimited by a single-input system and it is difficult to apply the method actually. In this paper we propose a method which transposes the nonlinear system with multi-input into an equivalent pseudo-linear system. And we apply the pseudo-linear system to a linear optimal regulator. To confirm the effectiveness of the proposed method, a transient stability control of the generator with an excitor and a governor is considered.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.1856-1857
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• 2006

The existing automation transfer systems such as AGV(Automated Guided Vehicle) have many problems (maintenance, accuracy, velocity, etc.) and wastes of a vast space and time. Hence we have suggested to LMTT(Linear Motor-based Transfer Technology). This paper deals with fundamental LMTT, and proposes a concept of mass reduction and propulsion control for LMTT when it is starting and reaching an object by using lift-force. By applying optimal controller and the repulsive lift forte in the LMTT, a large percent of vehicle weight is compensated and it reduces friction, then it needs less thrust force to propel the vehicle.

• International Journal of Control, Automation, and Systems
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• v.4 no.4
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• pp.456-465
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• 2006

The problem of recursive filtering far linear discrete-time systems with uncertainties is considered. A new suboptimal filtering algorithm is herein proposed. It is based on the fusion formula, which represents an optimal mean-square linear combination of local Kalman estimates with weights depending on cross-covariances between local filtering errors. In contrast to the optimal weights, the suboptimal weights do not depend on current measurements, and thus the proposed algorithm can easily be implemented in real-time. High accuracy and efficiency of the suboptimal filtering algorithm are demonstrated on the following examples: damper harmonic oscillator motion and vehicle motion constrained to a plane.

• Journal of the Korean Society for Precision Engineering
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• v.6 no.1
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• pp.85-92
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• 1989

For feedback control of a linear dynamic system the optimum linear state regulator (OLSR) can be implemented only if all states are available for feedback. This work demonstrates that when only the output state is available for feedback, a nonlinear controllers can give improved performance over that obtained by a proportional controller. This paper found the optimal control law by dynamic programming and principles of optimalityl. This, performances of both proportional and nonlinear controllers are compared with performance of optimum linear state regulator.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2001.12a
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• pp.137-140
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• 2001

In this paper, we design 75(Takagi-Sugeno) fuzzy controllers for the systems that can be represented by the 75 fuzzy model. We use inverse optimal approach in which the cost function is determined later than the Lyapunov function and its corresponding control input satisfying the design requirements such as stability and decay rate. The obtained design procedure is in the form of solving LMI(Linear Matrix Inequalities), thus very efficient in practice.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.265-268
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• 2005

This paper deals with the optimal design of a permanent magnet linear synchronous motor (PMLSM) with the analysis of prototype PMLSM. In the PMLSM, thrust ripple is one of the causes disturbing high-precision position control. Therefore, Response surface methodology (RSM), one of the optimization methods, is applied to obtain the shape decreasing thrust ripple of the prototype PMLSM. In the end, characteristic analysis of the PMLSM is performed by space harmonic method for shortening of a computation time, and final results is verified by finite element analysis.