• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.4
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• pp.53-61
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• 2000

능동 제어기를 설계하기 위해서는 제어대상 구조물의 수학모델의 구해야한다. 그러나, 무한차원의 구조물에 대하여 정확한 모델을 구하는 것은 불가능하므로 유한차원인 저차원화된 모델을 사용하여 제어기를 설계한다. 그러나, 실제 구조물과 저차원화된 모델사이의 오차에 의하여 제어기의 성능이 저하가 되면 제어기와 구조물의 상호작용, 지진과 같은 오란 등의 불확실성, 지진시 구조물의 동적 특성 변화로 인하여 제어기의 성능이 더욱 저하가 된다. 이러한 저하 요인은 제어기 설계시 요구되는 구조물의 수학모델에 대한 불확실한 요소로 작용하기 때문에 제어성능의 저하를 일으키며 응답의 불안정을 유발하기로 한다. 본 연구에서는 질량형 능동제어기(AMD)가 설치된 3층 건물 모형의 모델 오차에 관한 불확실성을 반영한 강인제어기법을 적용하여 제어성능과 안정성을 실험을 통하여 분석하였다. 강인제어 기법인 $\mu$ 합성법에 요구되는 여러 가지 가중함수인 주파수필터는 건물과 AMD의 특성, 모델 오차, 제어율과 AMD 성능의 , 측정잡음 및 지진외란의 특성 등을 고려하여 정량적으로 선택되었다. $\mu$합성법에 의하여 제어기를 설계하였으며 강인성을 비교하기 위하여 불확실성이 고려되지 않는 LQG 기법에 의한 제어기를 선택하였다. $\mu$합성법은 규정된 불확성에 대하여 제어의 강인성을 가지므로 동적특성이 바뀐 건물모형에 관한 강인성을 LQG 기법에 의한 제어성능과 비교하였다. 그 결과 동적특성이 변화된 건물에 대하여 $\mu$합성법만이 제어의 효율성이 유지되는 강인성을 나타내었다.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.4
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• pp.317-325
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• 2011

In this paper a robust voltage controller for a single-phase UPS inverter is newly presented. The voltage controller is designed using ${\mu}$-based robust control scheme to simultaneously guarantee robust stability and robust tracking performance in the presence of load variations. Firstly the robust performance of the resulting controller is theoretically confirmed via ${\mu}$-analysis. Then simulations and experiments for the single-phase inverter system with linear and nonlinear loads demonstrate feasibility of the proposed control method providing improved performance - good regulation and fast dynamic response.

• Journal of the Institute of Convergence Signal Processing
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• v.2 no.1
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• pp.101-107
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• 2001

The objective of this paper is to present a method for designing robust positioning control systems of a flexible arm using mixed $H_2/H_{\infty}$ and $\mu$ theory. We begin with a description of the flexible arm based on the model identification method and discuss the derivation of the model uncertainty. The validity of the obtained model is confirmed experimentally. Next, a robust controller is designed based on the mixed $H_2/H_{\infty}$ and $\mu$ theory by which we can improve robustness of the entire system. On this occasion, we also propose a general plant formation suitable to mixed $H_2/H_{\infty}$ control and $\mu$-theory. Finally, the effectiveness of the proposed design method is verified through experimentation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.2
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• pp.301-306
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• 2005

In this paper, a gain-boosting charge pump(CP) and a latch type voltage controlled oscillato.(VCO) with voltage controlled resistor(VCR) were proposed. The gain-boosting CP achieves good .current matching of less than 11$mu$V voltage difference between 43$mu$V and 32$mu$V in its output range from 0.8V to 2.3V. The VCO with VCR shows good linear characteristics over the range from 1V to 3V. The fabricated VCO exhibits -108dBc/Hz phase noise at a 100kHz and is comparable to that of the integrated LC-tank oscillator. The phase locked loop(PLL) with new circuits was simulated in a 0.35$mu$m CMOS process and showed 150$mu$s locking time.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5A
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• pp.849-859
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• 2006

This paper presents an extensive robust analysis of a ${\mu}$-controller in the hybrid system for various uncertainties using the benchmark cable-stayed bridge. The overall system robustness may be deteriorated by introducing active devices and the active controller may cause instability due to small margins. Therefore, a ${\mu}$-synthesis method that simultaneously guarantees the performance and stability of the closed-loop system (robust performance) with uncertainties is used for active devices to enhance the robustness in company with the inherent reliability of passive devices. The robustness of the ${\mu}$-synthesis method is investigated with respect to the additional mass on the deck, structural stiffness matrix perturbation, time delay of actuator, and combinations thereof. Numerical simulation results show that the proposed control system has the good robustness without loss of control performances with respect to various uncertainties under earthquakes considered in this study. Furthermore, the control system robustness is more affected by the perturbation of structural stiffness matrix than others considered in this study. Therefore, the hybrid system controlled by a ${\mu}$-synthesis method could be proposed as an improved control strategy for a seismically excited cable-stayed bridge containing many uncertainties.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4A
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• pp.233-240
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• 2005

In this paper, we have shown the gain recovery time of erbium-doped fiber amplifier(EDFA) in WDM add/drop networks can be reduced to less than $3\mu$sec by employing disturbance observer technique with PID controller which is based on 3-level EBFA model. The $3\mu$sec transient time is the fastest one ever reported and it is about $1\%$ of $250\mu$sec previously obtained from disturbance observer technique with PI controller which was based on 2-level EDFA model and it is also less than $200\mu$sec of commercially available EDFAs for WDM networks. We were able to obtain this result by analyzing various system characteristics as we change the parameters of disturbance observer and PID controller. If this result is applied to a commercial product, the product will do an important role in the future dynamic WDM networks.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.178-180
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• 1986

본 연구에서는 산업용 팩키지 보일러의 최적한 연소제어를 위하여 O/sub 2/ 제어기의 구성 및 PID제어 알고리즘을 도입하고 그것에 따른 하드웨어 및 소프트웨어를 고찰하였으며 그 결과 하드와이어드 논리제어기나 기존의 PC보다 분산제어의 효율적 처리가 가능하였다. BD/Micro PC 시스템에서 시퀀스 제어를 필요로하는 기능은 BD PC가, 아날로그 시스템을 다루는 PID 제어같은 기능은 .mu.C가 담당함으로서 제어범위가 넓어져 각종의 연산기능확대, BD PC와 .mu.C와의 데이터 링크, 그리고 고장진단등의 기능이 추가되었다.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.422-425
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• 1987

Auto-programming of sequencer was implemented by PLC-.mu.C system, to transform the PLC program in the relay ladder diagram.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.6
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• pp.41-48
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• 2002

This study is on the structural control experiment for a small scale three-story building structure employing on active mass damper subjected to earthquake loading. $\mu$-synthesis controllers, which belong to robust control strategies, were designed and their performance were experimentally verified. Frequency-dependent weighting functions corresponding to disturbance input and controlled output were defined and combined to produce optimal $\mu$-synthesis controllers. The experiment result shows 60-70% reduction in RMS responses under the band-limited white noise excitation and 30-45% reduction in peak responses under the scaled earthquake excitations. Good agreement was obtained between the simulations based on the identified mathematical model and experimental results. And the simulations for the system with uncertainties show that the designed controllers are robust within a specified range of uncertainties.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.1
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• pp.82-87
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• 1997

This paper presents a method about the modeling of the medium - small diesel engine for the speed control and designs the robust speed control system by the $\mu$-synthesis, which has good performance, in spite of the existence of model uncertainities and the external disturbance. We confirmed the validity of the proposed modeling method and the designed control system by $\mu$-synthesis through the experimental responses.