• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.3
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• pp.155-159
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• 2013

In this paper, a nonlinear matrix inequality problem and a nonlinear optimization problem are proposed for obtaining a structured static output feedback controller. The proposed nonlinear optimization problem has LMI (Linear Matrix Inequality) constraints and a nonlinear objective function. Using the conditional gradient method, the nonlinear optimization problem can be solved. A numerical example shows the effectiveness of the proposed approach.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.7
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• pp.501-513
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• 1987

Conditions for achieving noninteraction in nonlinear multivariable systems via the decomposition of state space are well established. The main contribution of this paper is to fully characterize the class of decomposing control laws. The characterization corresponds to a family of simple control laws which are applied to a standard decomposed system(SDS). The SDS is similar to the decomposed systems of Isidori, Krener, Gori-Giorgi, and Monaco but has a finer structure. The finer structure parallels the one used by Gilbert for linear systems. A weaker form of noninteraction, based on input-output behaviour, is decoupling. Some connections between decomposition and decoupling are also established. An example illustrating the importance of the results is given.

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.12
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• pp.1289-1295
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• 2012

An adaptive digital predistortion (PD) technique is proposed for linearization of power amplifiers (PAs) in multiple-input multiple-output (MIMO) transmitters. We consider a PD structure equipped with only one combined feedback path while conventional systems have multiple feedback paths. Hence, the proposed structure is much simpler than that of multiple feedback paths. Based on the structure, a new PD algorithm is derived. The simulation results show that linearization performance of the proposed method is almost the same as the conventional multiple feedback technique while the former is much simpler to implement than the latter.

• ICROS
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• v.17 no.4
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• pp.46-50
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• 2011

다변수 입출력 제어시스템에서 제어기를 설계하기 위해서는 단일 입출력 시스템에서와 마찬가지로 저주파수영역에서는 루프전달행렬의 크기가 작은 것이 요구되고, 측정잡음 및 플랜트의 불확실성이 존재하는 고주파수 영역에서는 루프전달행렬의 크기가 작게 되도록하여, 잡음의 영향이 출력에 적게 나타나고, 제어기가 포화되지 않도록 하며, 설계된 제어기가 플랜트 모델의 불확실성을 극복할 수 있게 하는 것이 필요하다. 본 원고에서는 각 전달 행렬들의 특이치의 최대 및 최소값들을 이용하여 다변수 제어기가 갖추어야 할 조건들을 정리하였다.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.291-294
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• 2006

This paper presents a decentralized input-output feedback linearizing controller for a multi-machine power system. Firstly, the controller is designed using input-output feedback linearization for modified outputs. Then we present a guideline for selecting gains of the controller and parameters in the modified outputs. Simulations illustrate the effectiveness of the proposed control scheme and the selection guideline.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.3
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• pp.233-236
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• 2015

In this paper, a nonlinear optimization problem is proposed to obtain a structured static output feedback controller for discrete time linear systems. The proposed optimization problem has LMI (Linear Matrix Inequality) constraints and a non-convex objective function. Using the conditional gradient method, we can obtain suboptimal solutions of the proposed optimization problem. Numerical examples show the effectives of the proposed approach.

• Journal of Industrial Technology
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• v.15
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• pp.209-215
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• 1995

In this paper, a controller design method for uncertain linear systems by output feedback is proposed. This method utilizes the LQG/LTR procedure for systems with uncertainties described in the time domain. It is assumed that the uncertainties satisfy the matching conditions and their bounds are known. First, a robust state feedback controller design method is introduced. Then, it is asymtotically recovered for the output feedback system by the loop transfer recovery(LTR) method under a certain condition.

• Korean Journal of Optics and Photonics
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• v.13 no.1
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• pp.58-64
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• 2002

Using Mach-Zehnder type intensity modulator, we stabilized a 10 GHz harmonically mode-locked dispersion-compensated fiber ring laser using a feedback controlling system, and we measured its stability. The laser was stabilized for more than 16 hours by controlling the cavity length to suppress the relaxation oscillation frequency component which had caused the laser output instability. The ms timing jitter and ms amplitude noise were measured to be 260-524 fsec and 4~11.5%, respectively, and BER test measurement showed a value of 10$^{-13}$ .

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.10a
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• pp.263-266
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• 1998

이 논문에서는 비선형 Channel의 등화기를 설계하기 위해 새로운 구조를 갖는 신경회로망을 제안하였다. 비선형 Channel의 동적 특성을 제대로 학습하기 위해 새로운 신경회로망은 은닉층 노드의 출력이 은닉층의 입력으로 되먹임되는 구조를 갖는다. 또한 이 논문에서는 제안한 신경회로망의 구조에 알맞는 학습 알고리즘을 제안하였다. 제안한 신경회로망과 학습 알고리즘의 성능은 Computer simulation을 통해 보였고, 그 결과는 기존의 Channel 등화기를 사용했을 경우보다 나은 결과를 보여 주었다.