• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.3
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• pp.335-340
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• 2008

In this paper, a decentralized fuzzy output feedback controller for nonlinear interconnected systems with time delay is proposed. The nonlinear interconnected system is represented to fuzzy system using Takagi-Sugeno (T-S) fuzzy model. The decentralized output feedback controller is designed(or stability of subsystems of the fuzzy interconnected system. The stable condition of the closed-loop subsystem is represented to the linear matrix inequality (LMI) form and control gain is obtained by LMI. An example is given to show the verification discussed throughout the paper.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.5C
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• pp.530-534
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• 2002

In the thesis, For improving the Stability of VCHRO(Voltage Controlled Hair-pin Resonator Oscillator) the new structure using the parallel feedback of the second harmonic is proposed for self-phase locking effect. This module is composed of wilkinson divider, frequency doubler, directional coupler, and bandpass filter using a hair-pin resonator, which are integrated into miniaturized hybrid circuit. The module exhibits output power of 2.5 dBm at 19.5 GHz, -29.83 dBc fundamental frequency suppression and -76.52 dBc/Hz phase noise at 10 kHz offset frequency from carrier of center frequency 19.5 GHz.

• Journal of IKEEE
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• v.23 no.2
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• pp.716-721
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• 2019

A novel switching differentiator-based backstepping controller for uncertain pure-feedback nonlinear systems is proposed. Using asymptotically convergent switching differentiator, time-derivatives of the virtual controls are directly estimated in every backstepping design steps. As a result, the control law has an extremely simple form and asymptotical stability of the tracking error is guaranteed regardless of parametric or unstructured uncertainties and unmatched disturbances in the considered system. It is required no universal approximators such as neural networks or fuzzy logic systems that are adaptively tuned online to cope with system uncertainties. Simulation results show the simplicity and performance of the proposed controller.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1136-1142
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• 2010

In this paper, we reduced the optical noise interference using the ASK modulation with optoelectronic feedback in a wireless optical system in which a lighting LED is used as a light source. The carrier frequency of 70 kHz was generated internally by the oscillation in the optoelectronic feedback circuit, and the output light was ASK modulated at a data rate of 9.6 kbps by opening and shortening the feedback loop with the input signal. In an environment with adjacent noise lights, the ASK modulation with optoelectronic feedback improved the signal to noise ratio by about 25 dB.

• Journal of the Korean Institute of Telematics and Electronics
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• v.19 no.5
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• pp.20-25
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• 1982

A realization method of the microwave oscillator is proposed by the inherently stable transistor with a cavily resonator feedback loop. The real Part of the output impedance of the inherently stable bipolar transistor can be made to be negative at the resonance frequency by the high-Q cavity feedback loop, and the oscillation condition can be obtained with the matching section of the load. In this work the microwave transistor oscillator is realized with a silicon bipolar transistor HXTR 2101 and a reentrani cavity, and characteristic of the output power 10m Watts at 2.33 GHz osc. frequency can be verified experimentally.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.111-114
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• 2003

In this paper, we consider the stabilization and $H_\infty$ control of linear systems with static output feedback control. The static output feedback control represents the simplest closed-loop control that can be realized in practice, and, moreover, it is less expensive to be implemented and is more reliable. In spite of its advantages, it is one of the open problems which is not sloved analytically or numerically yet. After decompose the closed-loop system into feedback form, by adopting the small gain theorem, we obtain a sufficient condition for stabilization and a sufficient condition for It control expressed as linear matrix inequalites. Finally, we show the usefulness of our results by a numerical example.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1511-1512
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• 2008

본 논문에서는 불확실성을 가지는 2차원 비선형 시스템을 안정화하기 위해서 추가 다이나믹스를 이용하여 출력 궤환 제어기법을 제안한다. 추가 다이나믹스는 이득값에 대한 것으로 0으로 수렴하는 구조를 지니고 있으며, 이 상태변수의 역수가 고이득의 역할을 함으로써 불확실성이 존재함에도 불구하고 제어목표를 이룰 수 있다. 더욱이 추가 다이나믹스는 그 설계에 의해 목표달성 후에는 본래의 초기값으로 복귀하는 구조를 지니고 있다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.2
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• pp.108-114
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• 1998

In this paper a second-order iterative learning control algorithm with feedback is proposed for use in real equipment systems requiring accurate and robust control. The convergence condition of the proposed algorithm is provided, and a simulation result is given to show the effectiveness of the proposed algorithm. It is shown that, by adding a feedback term in learning control algorithm, convergence speed, robustness to disturbances or system parameter variations can be improved.proved.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.175-176
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• 2007

본 논문은 매입형 영구자석 동기 전동기의 준 식스스텝 운전(Quasi six-step operation)을 위한 약자속 제어에 대한 새로운 방법을 제안한다. 제안된 방법은 전향 경로(feedforward path)와 궤환 경로(feedback path)로 구성되고 전향 경로는 1차원 참조표로 구성되며 궤환 경로는 전류제어기 출력과 과변조에 의해 제한된 전압의 차이를 이용한다. 제안된 방법을 통해 약자속 제어와 안티 와인드업(anti-windup) 제어가 동시에 이루어질 수 있다. 또한 제한된 직류단 전압 조건에서 식스 스텝(six-step) 운전에서 낼 수 있는 전동기의 최대 토크에 가까이 출력 토크를 발생시키면서 전류 제어를 계속할 수 있는 준 식스 스텝 운전이 가능하다. 제안된 방법의 유효성을 컴퓨터 시뮬레이션과 실험의 결과를 통해 입증하였다.

• Proceedings of the KIEE Conference
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• 1984.07a
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• pp.52-54
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• 1984