• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.331-334
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• 1993

It is a standard problem that designs a controller to minimize the $H_{\infty}$-norm of a given plant. By reducing a standard problem to a model-matching problem, we can obtain all the parameters which consist of a controller. After presenting a practical model and applying it to a tracking model, we design an $H_{\infty}$ controller and an LQ controller to concrete that $H_{\infty}$ control theory is far more robust than LQ control theory. And we show the advantage of an $H_{\infty}$ controller by obtaining a desired Bode diagram and comparing it with that of an LQ controller.

• 풍력에너지저널
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• 제2권1호
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• pp.74-81
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• 2011

This paper deals with the application of LQ control to the power curve tracking control of wind turbine. However, two more additional tasks are required to apply the LQR theory to wind turbine control. One is the tracking problem instead of regulation, because the wind turbine is controlled as variable speed and variable pitch. The other is LQ integral control., because the rotor speed should be tightly controlled without any steady state error. Starting from the analysis of wind characteristics, design requirement of a wind turbine control system is defined. A design procedure of LQ tracking with integral control is introduced. The performance of LQ tracking system is analyzed and evaluated by numeric simulation.

• 대한가정학회지
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• 제36권12호
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• pp.87-104
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• 1998

This study explores the life quality(LQ) of Korean married women compared to Korean married men's LQ, examines personal factors' and home environmental factors' influences to Korean married women's LQ via psychological factors such as social belongingness, positive emotion, self-esteem, and sense of intemal control in causal model, and explores Korean married women's perceived important factors and perceived enhancement required factors in life. The questionnaire was administered to 941 Korean married women and their husbands who have one or more children in Pusan. The results indicated that: 1. The overal and most sub dimensional LQ of Korean married women mark medium level and were lower than that of Korean married men's. Korean married women who is highly educated, keeps efficient communication with their husband, self-esteem, sense of internal control, social belongingness, and positive emotion, and possess high SES and much available resources shows higher LQ than those who doesn't. 2. The efficient communication with husband and available resources have direct and indirect influences on Korean married women's LQ. The psychological mediatory factors of these two variables' influences on women's LQ are such as social belongingness, positive emotion, self-esteem and sense of intemal control. SES has direct influence only and the educational level has indirect influence via social belongingness only on Korean married women's LQ. All these factors explain 58% of Korean married women's LQ variance. 3. Korean married women rank family health, family reconciliation, husband's success, and children's achievement as the very important factors in life. They also rank husbands success, economic abundant, family reconciliation, family health, and their self-actualization as the very required factors for enhancing the given LQ.

• 제어로봇시스템학회논문지
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• 제15권3호
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• pp.249-254
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• 2009

This paper studies the problem of pole placement by an LQ controller for system having two distinct real poles. Using the so-called Pole's Moving Range (PMR) drawn in the s-plane and relational equations between closed-loop system poles and weighting matrices, we calculate the state weighting matrix to move two distinct real poles to a pair of complex poles. By numerical examples, we show that the proposed method is applied to improve system performance.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.747-753
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• 1992

The modeling and control design schemes are developed for maglev systems with a combined lift and guidance. First, bond graph techniques are applied for modeling these multi-energy domain systems more logically and systematically. And the stability loop via pole placement and the performance loop via loop-shaping LQ control are designed. The suggested controller satisfies the required characteristics of stability and performance simultaneously. Finally, the robustness of the synthesized maglev control system is evaluated for the variations of air gap and vehicle mass through computer simulation.

• 수산해양기술연구
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• 제33권2호
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• pp.141-148
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• 1997

This paper is concerned with the vibration control of multi-layer structure for ultra-tall buildings and main tower of large bridge etc. We have modeled the multi-layer structure with the distributed mass system as the lumped mass system of two-degree-of-freedom structure and made experimental equipment. The LQ optimal control theory is applied to the design of the control system. The designed control system is simulated by computer. As a result, the LQ regulator showed good vibration control performance with impact excitation.

• 제어로봇시스템학회논문지
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• 제16권2호
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• pp.134-139
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• 2010

In order to overcome some problems of existing anti-windup methods, this paper defines LQ (Linear Quadratic) observer and proposes a new anti-windup method using the LQ observer. LQ observer is derived by linear quadratic optimization in order to calculate controller states, which make the controller outputs equal to the plant inputs. And we propose an algorithm so that it can be implemented by a digital controller easily. The relationship between the design parameters and the anti-windup performance is shown via some numerical examples, which cover the cases with the anti-windup method using LQ observer designed and the case without it. Finally, the anti-windup performance of the proposed method is exemplified via comparison with the existing model-based conditioning scheme method[4].

• 제어로봇시스템학회논문지
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• 제13권11호
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• pp.1048-1052
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• 2007

This paper presents a rank-constrained linear matrix inequality(LMI) approach to simultaneous linear-quadratic(LQ) optimal control by static output feedback. Simultaneous LQ optimal control is formulated as an LMI optimization problem with a nonconvex rank condition. An iterative penalty method recently developed is applied to solve this rank-constrained LMI optimization problem. Numerical experiments are performed to illustrate the proposed method, and the results are compared with those of previous work.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.420-424
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• 1994

In this paper, an active suspension system considering the wheel hop is studied for a quarter car model. A LQ controller controls an active suspension system in which a vibration absorber is attached to the wheel axis. The vibration absorber is adopted to reduce the vibration near the natural frequency of the unsprung mass, and the LQ controller is used to control the vibration near the natural frequency of the sprung mass. The perfomance of the control system considering the wheel hop is compared with that of a LQ control system.

• Journal of Advanced Marine Engineering and Technology
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• 제26권5호
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• pp.544-553
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• 2002

The recent amount of container freight continuously has been increased, but the low efficiency of container crane causes jamming frequently in transportation and cargo handling at port. It is required that the working velocity and safety are improved by control of moving the trolley as quick as possible without large overshoot and any residual swing motion of container at the destination. In this paper, a LQ controller for a container crane is proposed to accomplish an optimal design of improved control system for minimizing the swing motion at destination. In this scheme a mathematical model for the system is obtained in state space form. Finally, the effectiveness of the proposed controller is verified through computer simulation.