• Journal of the military operations research society of Korea
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• v.30 no.1
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• pp.153-167
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• 2004

This study focuses on building the wartime air operation model to evaluate the airfield capability. There are some uncertainties in the process of air operation such as mission flying time, turn around time, mission damage or kill rate, weather condition, and so on. Airplanes, on the way to the airbase after completing mission flight, may have been in queue on the holding point due to the unusable condition of airfield. And then, they may sometimes need to go other airbases due to the shortage of fuel. Under those uncertainties, this model is to evaluate the airfield capability in the wartime air operation using simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.4
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• pp.875-885
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• 1999

This paper presents an application of LMI-based techniques to the mixed $H_2/ H_\infty$ control of an inverted pendulum. The linear model of the inverted pendulum represented by an LFR(Linear Fractional Representation) model of uncertainties is derived. Considered uncertainties are three nonlinear components and a parameter uncertainty Augmenting the LFR model by adding weighting functions, we get a generalized plant, for which we design a mixed $H_2/ H_\infty$ controller using the LMI technique. To evaluate control performances and robust stability of the mixed $H_2/ H_\infty$ controller designed, we compare it with the $ H_\infty$controller through the simulation and experiment. The mixed $H_2/ H_\infty$ controller shows the better control performances and robust stability than the $H_\infty$controller in the sense of pendulum angle.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.5
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• pp.406-413
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• 2007

This paper proposes a self-recurrent wavelet neural network(SRWNN) based adaptive backstepping control technique for the robust steering control of autonomous underwater vehicles(AUVs) with unknown model uncertainties and external disturbance. The SRWNN, which has the properties such as fast convergence and simple structure, is used as the uncertainty observer of the steering model of AUV. The adaptation laws for the weights of SRWNN and reconstruction error compensator are induced from the Lyapunov stability theorem, which are used for the on-line control of AUV. Finally, simulation results for steering control of an AUV with unknown model uncertainties and external disturbance are included to illustrate the effectiveness of the proposed method.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.11
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• pp.1038-1043
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• 2010

In this paper, an adaptive sliding-mode formation control and collision avoidance are proposed for electrically driven nonholonomic mobile robots with model uncertainties and external disturbances. A sliding surface based on the leader-follower approach is developed to achieve the desired formation in the presence of model uncertainties and disturbances. Moreover, by using the collision avoidance function, the mobile robots can avoid the obstacles successfully. Finally, simulations illustrate the effectiveness of the proposed control system.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.1
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• pp.14-20
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• 2015

This paper describes the design of a robust H-infinity attitude controller for a quad-rotor. The linear model of a quad-rotor was estimated using PEM (Prediction Error Minimization) method with experimental input and output data. To design an attitude controller, an extended plant was constructed by adjusting several uncertainties and weighting functions. An H-infinity controller was obtained by applying H-infinity methodology to the extended plant. Through frequency-domain analysis, it was shown that the designed controller can overcome uncertainties up to 75% of the plant model. The performance and robustness of the controller were verified through time-domain simulation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.7
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• pp.1129-1134
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• 2008

This paper proposes a reliability evaluation for interconnection planning using a tie line equivalent assisting generator model (TEAG) that considers the uncertainties of the interconnected transmission systems and the tie lines. Development of this model was triggered by the need to perform probabilistic reliability evaluations on the NEAREST (North East Asia Region Electric Systems Tied) interconnection. The TEAG is the basis for the newly developed interconnection systems reliability evaluation computer program, NEAREL. The model is capable of considering uncertainties associated with generators, tie lines, and the tied grids. Reliability evaluations for six interconnection scenarios involving the power systems of six countries in the Asian north eastern region were performed using NEAREL. Sensitivity analysis was used to determine reasonable tie line capacities for three interconnected country scenarios of the six countries. Test results and summarized comments of the scenarios are included in the paper.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.5 no.2
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• pp.145-150
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• 2005

We proposed the indirect adaptive fuzzy model based sliding mode controller to control nonaffine nonlinear systems. Takagi-Sugano fuzzy system is used to represent the nonaffine nonlinear system and then inverted to design the controller at each sampling time. Also sliding mode component is employed to eliminate the effects of disturbances, while a fuzzy model component equipped with an adaptation mechanism reduces modeling uncertainties by approximating model uncertainties. The proposed controller and adaptive laws guarantee that the closed-loop system is stable in the sense of Lyapunov and the output tracks a desired trajectory asymptotically.

• Journal of Electrical Engineering and Technology
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• v.5 no.2
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• pp.239-245
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• 2010

Today, as power trades between generators and loads are liberalized, the uncertainty level of power systems is rapidly increasing. Therefore, transmission operators are required to incorporate these uncertainties when establishing an investment plan for effective operation of transmission facilities. This paper proposes the methodology for an optimal solution of transmission expansion plans for the long-term in a deregulated power system. The proposed model uses the probabilistic cost of transmission congestion for various scenarios and the annual increasing rates of loads. The locations and the installation times of expanded transmissions lines with minimum cost are acquired by the model. To minimize the investment risk, the Mean-Variance Markowitz portfolio theory is applied to the model. In a case study, the optimal solution of a transmission expansion plan is obtained considering the uncertain power market.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.3 s.96
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• pp.128-135
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• 1999

A driving simulators of aircraft and vehicle may consist of hydraulic power systems with many single-rod cylinders. The single-rod hydraulic systems are convenient but need more robust control scheme in order to achieve a reliable performance against the wide range of operating disturbances and the inherent model uncertainties. $H_{\infty}$ control scheme was implemented to the 2 degree-of-freedom hydraulic device similar to the simple driving simulator. With the reasonable disturbances from sensor, base and pump and also with the linearization of model, the simulation and experimental results showed good agreements.

• International conference on construction engineering and project management
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• 2011.02a
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• pp.330-334
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• 2011

Build-operate-transfer (BOT) projects are privatized infrastructure undertakings that face long-term investment risks and uncertainties. To ensure these projects can be completed on time and operated according to performance specifications, governments usually require BOT concessionaires to furnish performance bonds as a security. However, in order to attract investment, governments often provide abandonment rights for concessionaires to deal with investment risks and uncertainties. In the context of real options, these abandonment rights will increase project value, but the furnish of performance bonds will reduce this value. Currently in the BOT context, there is no real option model that can handle explicitly the impact of performance bonds on project value. In this paper, a real option valuation model is derived to deal with this important issue. The Taiwan high-speed rail project is used as a case study to show the applicability of the proposed model.