• 제어로봇시스템학회논문지
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• 제4권1호
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• pp.62-67
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• 1998

Gimballed Inertial Navigation Systems(GINS) are sophisticated autonomous electro-mechanical systems which supply the position, velocity and attitude of the vehicle on which they are mounted. In order to maintain accuracy of outputs, the GINS are required to regularly calibrate senior errors. However, existing calibration methods take up a long time due to multiposition alignments needed to increase accuracy. A particular system formulation for calibration of a GINS is proposed to enhance system observability and thus to expedite calibration procedure. Performance of the proposed calibration method is compared with existing methods such as Schuler test and muliposition alignment. Simulation studies show the proposed system formulation associated with a suggested suboptimal filter is accurate as well as efficient in error identification essential to GINS calibration.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제15권3호
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• pp.200-207
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• 2015

This paper proposes an active damping control method for a grid-side converter that has an LCL grid filter in the back-to-back converter. To remove the resonant frequency components produced by the LCL filter, it is necessary to measure the grid current. To do this, sensors must be added. However, it is not necessary to add sensors because the grid current is estimated by designing a suboptimal observer. In order to remove the nonlinearity and to gain fast response of control, both feedback linearization and sliding mode control are applied. The proposed method is verified through a simulation.

• Asian-Australasian Journal of Animal Sciences
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• 제24권3호
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• pp.394-399
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• 2011

The effect of intermittent feeding on growth, feed utilization and body composition of subadult olive flounder fed extruded pellet (EP) in suboptimal temperature ($13.5{\pm}2.10^{\circ}C$) was determined. Two hundred twenty five subadult fish averaging 272 g were randomly distributed into fifteen of 300 L circular flow-through tanks (fifteen fish per tank). Five treatments with different days of feeding a week were prepared in triplicate: fish were hand-fed with EP to apparent satiation once a day, seven days a week (7DF), which was used as the control group or consecutive six, five, four and three days a week, for 12 weeks, referred to as 6DF, 5DF, 4DF and 3DF treatments, respectively. Weight gains and specific growth rates of fish in 6DF treatment were higher than those of fish in 7DF, 4DF and 3DF treatments, but not different from those of fish in 5DF treatment. Daily feed intake of fish in 6DF and 7DF treatments was higher than that of fish in 5DF, 4DF and 3DF treatments. Feed efficiency and protein efficiency ratio of fish were not different among treatments. There was no difference in the chemical composition of fish between treatments. Results of this study demonstrated that feeding five days per week could be recommended for subadult olive flounder fed extruded pellet in suboptimal temperature.

• 한국통신학회논문지
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• 제12권4호
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• pp.386-398
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• 1987

本 論文은 PWM(Pulse Width Modulation)인버어터의 스위칭作用에 의해서 發生하는 高周波 影響을 最小化하기 위한 Suboptimal PAWM(Pulse Amplitude Width Modulation)을 提示하였다. 本 方式은 Suboptimal PWM에서 THD(Total Harmonic Distorition)가 最小가 되는 固定點(基本波 電壓 u1=1.2)에서 하나의 스위칭패턴을 決定하였다. 그리고 電壓은 DC Link에서 DC Chopper에 의해 制御하게 하고 인버어터에서는 단지 高周波만을 制御하도록 하였다. 本 方式은 3相 誘導電動機의 VSD(Variable Speed Drive)에 適用하여 電動機의 騷音, 인버어터의 線間電壓 및 電流, 電流高周波 스펙트럼을 測定하였으며, 他 方式과 比較해 보았다. 그 結果로부터 本 方式의 妥當性을 立證할 수 있었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1464-1468
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• 1997

We propose a decentralized state estimation method in the multisensor state estimation problem. The proposed method bounds teh maximum energy gain from uknown external disturbances to the estimation errors in the suboptimal case. And we formulate aternative H/sip .inf./ filter gain equatiions with teh idea that the suboptimal H.$^{\infty}$ filter is the special form of Kalman filter filter whose state equations are defined in indefinite inner product spaces. Using alternative filter gain equations we design the decentralized $H^{\infty}$ state estimator which is composed of local filters and central fusion filter that are suboptimal in the $H^{\infty}$ sense. In addition, the proposed update equations between global and local data can reduce unnecessary calculation burden efficently.y.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1477-1480
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• 1997

This paper is concerned with the design of a suboptimal robust Kalman filter using LMI approach for system models in the state space, which are subjected to parameter uncertainties in both the state and measurement atrices. Under the assumption that augmented system composed of the uncertain system and the state estimation error dynamics should be stable, a Lyapunov inequality is obtained. And from this inequaltiy, the filter design problem can be transformed to the gneric LMI problems i.e., linear objective minimization problem and generalized eigenvalue minimization problem. When applied to uncertain linear system modles, the proposed filter can provide the minimum upper bound of the estimation error variance for all admissible parameter uncertainties.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.841-846
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• 1990

In this study, a design method to obtain a robust suboptimal regulator for linear multivariable system is presented. This new design method is based on the optimal regulator design method using eigen-structure assignment and it uses additional cost function which represent robustness of the closed loop system. When we design the regulator using pole assignment method for linear multivariable system we have extra degree-of-freedom after assigning desired eigenvalues of the closed loop system in determining the feedback gain. So we assign additional robust suboptimal regulator. In this study we also feedback the system output for more practical applications.

• 대한전기학회논문지
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• 제33권10호
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• pp.396-401
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• 1984

This paper present a method of using simplified models for deriving suboptimal controllers to the original higher-order systems. Routh approximation method is a very useful technique for reducing the order of a linear systems. This method dose not require a knowlege of system eigenvalues and eigenvectors and possesses many desirable features such as preservation of reduced order model stability and minimum computational requirements. These properties are utilized to derive suboptimal controllers in this paper. In order to implement htese ocntrollers on the original system, the relationship between the state vectors of the original system and the reduced order models is required. A procedure fir evaluating an approximate aggregation matrix is also developed. A numerical example is given for the illustration of this method, shich is compared with the existing Model aggregation method in the resultant figures.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.1131-1133
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• 1996

In this paper, we consider the mixed $L_1/H_{\infty}$ problems of finding internally stabilizing controllers which minimize the peak-to-peak gain of a certain closed loop transfer function with $H_{\infty}$-norm constraint on other closed loop transfer function(or vise versa). This problem is a useful framework for designing a controller with the norm constraints upon time and frequency domain. We formulate the mixed $L_1/H_{\infty}$ problem as LMI problems by using the reachable set. This paper offers the sufficient condition for the existence of suboptimal state feedback controller, and shows that suboptimal solution can be obtained by solving a finite-dimensional convex optimization and a line search.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.255-259
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• 1989

A suboptimal output feedback controller is designed and applied to a flexible rotor bearing system in order to control the unstable or lilghtly damped vibrations. The reduced order model is the truncated modal equation of the distributed parameter system obtained through the singular perturbation. The instability problem arising from the spillover effects caused by the uncontrolled high frequency modes is prevented through the constrained optimization by incorporating the spillover term into the performance index. The efficiency of the proposed method is demonstrated experimentally with a flexible rotor by using a magnetic bearing.