• The Journal of the Acoustical Society of Korea
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• v.36 no.5
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• pp.353-360
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• 2017

The single sensor based acoustic reflection control system separates the incident and reflected signals from the single sensor output, and reduces the reflected signal by generating an out-of-phase signal from the incident signal component. In this paper, we propose an optimal filter design method for a single sensor based reflection control system. In the proposed method, it is shown that the optimum control filter design is possible by using the measured impulse responses of the reflection and control paths. The reflection control algorithm based on the proposed optimal filter achieves better performance than the conventional adaptive filter-based algorithm and effectively controls the reflection without the initial convergence time. We performed computer simulations using the signals obtained in a 1-dimensional acoustic duct environment, and from the simulation results, it was confirmed that the proposed optimal filter has robust performance even in noisy environment.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.6
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• pp.37-46
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• 2001

In this research, a controller design method based on optimization is proposed that can satisfy constraints on maximum responses of building structures subject to around excitation modeled by partially stochastic process. The class of controllers to be optimized is restricted to LQR. Weighting matrix on controlled outputs is used as design variable. Objective function, constraint functions and their gradients are computed by the parameterization of control gain with Riccati matrix. Full state feedback controllers designed by proposed optimization method satisfy various design objectives and their necessary maximum control forces are computed for the production of actuator. LQG controllers composed of Kalman filter and LQR designed by proposed method perform well with little deterioration. So it is possible to design output feedback controllers satisfying constraints on various maximum responses of structures.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.1
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• pp.11-19
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• 2005

In order to improve dynamic stall characteristics of an oscillating airfoil, optimal design has been performed for fixed nose droop and Gurney flap. Fixed nose droop is known to be very effective to improve pitching moment characteristics but may cause degeneration of aerodynamic lift at the same time. On the other hand, Gurney flap has the opposite characteristics. For fixed nose droop, location and angle are chosen as design variables, while length is defined as design variable for Gurney flap. Higher order response surface methodology and sensitivity based optimal design method are employed to handle highly nonlinear problem such as dynamic stall. Optimal design has been performed so that lift and pitching moment are simultaneously improved. The design results show that aerodynamic characteristics can be remarkably improved through present design approach and the present passive control method is as good as active control method which combines variable nose droop and Gurney flap.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2639-2641
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• 2000

계수적 구간 불확실 플랜트를 안정화하는 강인 제어기의 설계의 방법으로서 고정차수 극 배치(FOPA : Fixed Order Pole Assighnment) 알고리즘을 이용할 수 있다. FOPA 알고리즘에 의해서 강인제어기 계수의 집합은 선형제약조건으로 표현되고, 이 조건을 만족하는 임의의 한점은 주어진 불확실 시스템을 안정화한다. 본 논문에서는 선형제약조건으로 주어진 제어기 계수의 집합에서 외란의 에너지를 최소화하는 제어기를 구하는 알고리즘을 제안한다. 일반적으로 전역 최적해을 구하는 문제는 BMI(bilinear matrix inequalities)로 표현되지만 제어기의 계수를 고정했을 때는 LMI(lineal matrix inequalities)로 간략화되기 때문에 제어기계수에 대한 최소화와 성능지수에 대한 최소화를 반복함으로써 국부 최적해를 구할 수 있다. 제안한 알고리즘의 효용성을 보이기 위해 제어기 설계 예를 보이고, 그 성능을 비교 분석한다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.2
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• pp.8-15
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• 2000

This study presents an H$_{\infty}$ optimal controller synthesis by the frequency domain analysis of weighting function. The main purpose of our study is to visualize weighting function domains and open loop transfer function domains that satisfy robustness and performance. Also we aim to simplify the iterative algorithm for H$\infty$ optimal controller synthesis. We report that the designed regulator by the proposed method in this paper satisfies the desired specifications and performance in spite of the plant uncertainty variation at any operating point.

• Journal of IKEEE
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• v.1 no.1 s.1
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• pp.19-30
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• 1997

In this paper we design the optimal satellite-tracking antenna $H{\infty}$ control system using genetic algorithms. To do this, we give gain and dynamics parameters to the weighting functions and apply genetic algorithms with reference model to the optimal determination of weighting functions and design parameter ${\gamma}$ that are given by Glover-Doyle algorithm which can design $H{\infty}$ controller in the state space. These weighting functions and design parameter ${\gamma}$ are optimized simultaneously in the search domain guaranteeing the robust stability of closed-loop system. The effectiveness of this satellite-tracking antenna $H{\infty}$ control system is verified by computer simulation.

• Proceedings of the KIEE Conference
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• 2008.04a
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• pp.209-210
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• 2008

본 논문에서는 제어기에 승산형 섭동을 가지는 제어기와 이산시간 특이시스템을 안정화시키는 비약성 제어기 설계방법을 제시한다. 강인 비약성 제어기가 존재할 조건과 제어기 설계방법을 블록최적화가 가능한 선형 행렬부등식 접근방법으로 제안한다. 또한, 제어기의 약성 성도를 표시하는 비약성 척도를 동시에 계산함으로 승산형 섭동의 제어기 최대 변동정도를 제시한다. 제안한 비약성 제어기는 제어기의 이득 변동에도 불구하고 이산 시간 특이시스템의 강인 안정성을 보장한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.9
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• pp.817-823
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• 2017

In the past, research has been conducted on the development of an adaptive cruise control algorithm considering fuel efficiency, and an adaptive cruise control system considering fuel efficiency have been developed. However, research on optimizing vehicle and adaptive cruise control parameters in order to maximize performances is insufficient. In this study, the design optimization of vehicle and control parameters considering fuel efficiency, trackability, ride comfort and safe distance is performed. This paper proposes performance measures of vehicle behavior and develops an adaptive cruise control system. In addition, based on the screening of vehicle parameters that significantly influence performances, kriging surrogate models are constructed through a sequential design of experiment, and kriging surrogate model-based design optimization is performed to maximize fuel efficiency and satisfy target performances.

• Nuclear Engineering and Technology
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• v.26 no.1
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• pp.32-40
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• 1994

A digital control system for the steam generator oater level control is developed using the optimal control technique. To describe the more realistic situation, a feedwater valve actuator of the first order lag is included in the overall control system. The optimal gains are obtained by the LQ method which imposes the constraints on the feedwater valve motion as well as on the deviation between the input demand signal and the output feedwater. Developed also is a Kalman observer on account of the flow measurement uncertainty at low power. And a digital controller on the feedback loop is designed which makes the system maintain the same stability margins for all power ranges. The simulation results show that the optimal digital system has good control characteristics despite the adverse dynamics of the steam generator at low power.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2953-2955
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• 2000

본 논문에서는 전문가의 지식이 없는 상황에서 자동적으로 최적의 퍼지 제어기를 설계하는 방법에 대해 연구한다. 먼저 퍼지 제어기의 규칙 설정을 위해 기존의 PID 제어기의 입출력 데이터를 클러스터링한다. 군집된 데이터들로부터 클러스터의 수를 파악하고 이를 바탕으로 퍼지 제어를 위한 규칙의 수를 결정한다. 둘째로 퍼지 제어기의 여러 파라미터들은 유전자 알고리즘을 적용하여 최적화한다. GA를 이용한 최적화 과정에서는 성능평가 기준으로 기준입력에 대한 시스템 응답간의 오차와 오버슈트의 크기를 사용하여 응답이 빠르고 안정적인 제어기를 설계하도록 진화방향을 설정한다. 이렇게 만들어진 퍼지 제어기의 성능을 기존의 PID 제어기와 비교 평가한다