• Structural Engineering and Mechanics
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• 제67권1호
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• pp.33-43
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• 2018

The dynamic output-feedback robust control method based on linear matrix inequality (LMI) method is presented for suppressing vibration response of a functionally graded material (FGM) beam with piezoelectric actuator/sensor layers in this paper. Based on the reduced model obtained by using direct mode truncation, the linear fractional state space representation of a piezoelectric FGM beam with material properties varying through the thickness is developed by considering both the inherent uncertainties in constitution material properties as well as material distribution and the model error due to mode truncation. The dynamic output-feedback robust H-infinity control law is implemented to suppress the vibration response of the piezoelectric FGM beam and the LMI method is utilized to convert control problem into convex optimization problem for efficient computation. In numerical studies, the flexural vibration control of a cantilever piezoelectric FGM beam is considered to investigate the accuracy and efficiency of the proposed control method. Compared with the efficient linear quadratic regulator (LQR) widely employed in literatures, the proposed robust control method requires less control voltage applied to the piezoelectric actuator in the case of same control performance for the controlled closed-loop system.

• 자원ㆍ환경경제연구
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• 제18권1호
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• pp.105-138
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• 2009

본 연구는 한강의 수질측정망에서 관측된 오염물질별 연평균 오염도를 이용하여 지난 15년 동안 수질오염도의 공간적 분포에 유의한 변화가 발생하였는지를 분석하였다. 구체적으로 각 오염물질별의 비모수적 커널확률밀도함수를 추정하였고, 연도간 유의한 변화가 있는지 검정하였다. 또한 일반화된 엔트로피 계열의 불평등지수를 구하고, 부트스트래핑 기법을 통해 불평등지수의 차이가 유의한지를 검정하였으며, 순위 상관을 이용하여 오염도 순위의 동태적인 측면을 분석하였다. 분석결과 최근 15년 동안 수질오염도의 불균등 정도는 전반적으로 완화되거나 일정한 수준을 유지하였고, 오염도 순위에 동태적인 변화는 거의 일어나지 않은 것으로 나타났다.

• 대한교통학회지
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• 제29권1호
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• pp.71-79
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• 2011

전통적으로 동적 교통망 모형들은 실시간 교통운영 문제를 위한 도구로 인식되어 왔다. 이와 같은 모형들을 활용하는 방안 중 하나는 예측통행시간을 생성하는 것이다. 예측통행시간 정보는 통행자들이 혼잡한 지역에서 덜 혼잡한 지역으로 경로를 전환할 수 있도록 해 주는데 이는 교통망의 용량을 효과적으로 활용하게 한다. 이러한 접근 방법은 돌발상황이 발생했을 때 매우 효과적일 것으로 예상된다. 이 때 고려해야 할 사항은 통행시간정보가 미래 통행여건 자체에 영향을 준다는 점이다. 이로 인해 예기치 못한 과잉반응(over-reaction)을 야기할 수 있으며 예측정보의 신뢰도를 떨어뜨리는 요인으로 작용할 수도 있다. 본 연구에서는 돌발상황 발생 시를 대상으로 교통망 차원의 통행시간 예측모형을 제시한다. 이 모형에서는 모든 운전자가 개인 차내 단말기를 통해 상세한 교통정보를 이용할 수 있으며 이러한 정보를 바탕으로 경로선택에 관한 의사결정을 할 수 있다고 가정하였다. 경로기반(route-based)의 확률론적 변등부등식(stochastic variational inequality)을 통행시간예측의 기본모형으로 사용하였으며 운전자의 경로전환의사를 반영하기 위해 경로전환함수를 적용하였다. 컴퓨터 프로그램과 간단한 교통망 분석을 통해 제안된 모형의 특성을 살펴보았다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.203-207
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• 1991

In this paper, a linear stocastic dynamic system with norm - bounded plant perpurbations and norm - bounded noise covariarice is studied. Instead of Bellman-Gronwall inequality used in previous study, Lyapunov stability theorem is used to derive stability condition. The new condition is of more compact form than the previous result.

• 한국해양공학회지
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• 제26권3호
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• pp.20-25
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• 2012

In this paper, the authors propose a new approach to the control problem of marine vessels that are moored or controlled by actuators. The vessel control system is basically based on Dynamic Positioning System (DPS) technology. The main object of this paper is to obtain a more useful control design method for DPS. In this problem, the control allocation is a complication. For this problem, many results have been given and verified by other researchers using a two-step process, with the controller and control allocation design processes carried out individually. In this paper, the authors provide a more sophisticated design solution for this issue. The authors propose a new design method in which the controller design and control allocation problems are considered and solved simultaneously. In other words, the system stability, control performance, and allocation problem are unified by an LMI (linear matrix inequality) based on control theory. The usefulness of the proposed approach is verified by a simulation using a supply vessel model.

• The Journal of Asian Finance, Economics and Business
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• 제7권12호
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• pp.593-604
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• 2020

This study analyzes human development convergence and the impact of funds transfer to the regions using σ and β-convergence analysis method. Observations were made in all Indonesia's provinces in the period 2010-2019. The coefficient of variation calculation shows a dispersion in the inequality of human development, which means that convergence occurred. This is also documented by the clustering analysis results developed in the study. The results are in line with the hypothesis of neoclassical theory, which shows the tendency for provinces with lower human development levels to grow relatively faster. The dynamic panel data approach with the GMM model shows that a model built with explanatory variables for transfer of funds to regions may lead to the process of convergence of human development - 2.21% per year or 31 years to cover the half-life of convergence. This is a consequence of the Special Allocation Fund and the Village Fund, which positively impact the convergence process, and the General Allocation Fund and the Revenue Sharing Fund with negative signs slowing the convergence process. This evidence opens opportunities to review the justification of the weighting component in determining the amount of funds transferred to the region to accelerate the convergence process of human development.

• The Journal of Asian Finance, Economics and Business
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• 제7권12호
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• pp.647-655
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• 2020

This study introduced income mobility analysis using pseudo-longitudinal panel data from Family Income and Expenditure Survey (FIES) to consider the dynamic process of individual's well-being through time. Since there is no comprehensive measurement of income mobility because of its dynamic process, various income mobility indices such as Chi-square, Average Jump Index, Atkinson et al. Mobility Ratio, and Shorrocks' Mobility Index were used. These indices revealed that Filipino households' income movements are more mobile than expected, and their income status improved from 2000 to 2015. As income mobility takes place, income inequality is reduced by 91.80 percent (91.80%). Furthermore, the growth effect is the main factor of income mobility. This indicates that households took the economic opportunities from economic growth to earn more. However, income mobility due to transfer effect (transfer of income from one household to another through lottery winning and borrowing) increased when the economy is not good. The higher income mobility due to growth effect compared to transfer effect, whether the economy is good or bad, means that households learned how to use their income in savings, investments, and entrepreneurship. This is the result of a successful financial literacy program of the government wherein households realized financial stability and security.

• 제어로봇시스템학회논문지
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• 제19권9호
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• pp.846-852
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• 2013

In this paper, the authors propose a new approach to control problem of the marine vessels which are moored or controlled by actuators. The vessel control problem in the specified area is called a DPS (Dynamic Positioning System). The main objective of this paper is to obtain more useful control design method for DPS. In this problem, a complicate fact is control allocation which is a numerical method for distributing the control signal to the controlled system. For this, many results have been given and verified by other researchers using two individual processes. It means that the controller design and control allocation design process are carried out individually. In this paper, the authors give more sophisticated design solution on this issue. In which the controller design and control allocation problem are unified by a robust controller design problem. In other word, the stability of the closed-loop system, control performance and allocation problem are unified by an LMI (Linear Matrix Inequality) constraint based on $H_2/H_{\infty}$ mixed design framework. The usefulness of proposed approach is verified by simulation with a supply vessel model and found works well.

• Elastomers and Composites
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• 제34권4호
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• pp.321-331
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• 1999

타이어 가황공정(curing process)은 타이어 제조를 위한 최종공정으로 여러 개의 고무배합물 층으로부터 성형된 그린타이어(green tire)를 가황기(mold)내에서 고압/고온 조건하에 유지시킴으로써 원하는 형상을 얻게 하고, 아울러 각 고무배합물이 고탄성을 갖도록 물성을 변화시키는 공정이다. 본 연구에서는 타이어 품질의 향상을 위해 가황공정을 수치적으로 최적화하는 기법을 개발하였다. 먼저, 가황공정 중 가황매체(cure media)의 최적공급 조건을 경정하기 위해 제약조건을 갖는 동적최적화문제(dynamic constrained optimization problem)로 정형화하였다. 즉, 가황기 내의 전열 및 가황 반응 현상을 묘사하는 공정모델로 표현되는 등위제약조건(equality constraint)과 가황매체가 갖는 온도의 한계를 표현하는 부등위제약조건(Inequality constraint) 아래 목적함수를 최적화 시켰다. 다음, 공급되는 가황매체의 최적조건을 결정하기 위해 구성된 최적화문제를 유한요소법(FEM)과 complex 알고리즘을 적용하여 풀었다.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.418-429
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• 2018

This paper studies the decentralized position/force control problem for constrained reconfigurable manipulator without torque sensing. A novel joint torque estimation scheme that exploits the existing structural elasticity of the manipulator joint with harmonic drive model is applied for each joint module. Based on the estimated joint torque and dynamic output feedback technique, a decentralized position/force control strategy is presented. In order to solve the problem of controller parameter perturbation, the non-fragile robust technique is introduced into the dynamic output feedback controller. Subsequently, the stability of the closed-loop system is proved using the Lyapunov theory and linear matrix inequality (LMI) technique. Finally, two 2-DOF constrained reconfigurable manipulators with different configurations are applied to verify the effectiveness of the proposed control scheme in numerical simulation.