• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.534-538
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• 2017

There are three types of robots that move on the ground classified as drivetrain. Wheels, tracks and Legs. Wheels and tracks are much easier to construct and control, but they have problems passing through obstacles like people. This paper discusses the design of line tracing using Theo Jansen, one of multi-legged walking mechanism. In order to increase the moving speed, the Jansen mechanism is designed by maximizing the objective variable as GL (Ground Length), GAC (Ground Angle Coefficient). In this project, only three sensors were attached and Arduino was used for optimal control of the motor using the sensor values.

• Journal of IKEEE
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• v.18 no.2
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• pp.255-262
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• 2014

The uncertain integral linear system is the integral-augmented uncertain system to improve the resultant performance. In this note, for a MI(Multi Input) uncertain integral linear case, Utkin's theorem is proved clearly and comparatively. With respect to the two transformations(diagonalizations), the equation of the sliding mode is invariant. By using the results of this note, in the SMC for MIMO uncertain integral linear systems, the existence condition of the sliding mode on the predetermined sliding surface is easily proved. The effectiveness of the main results is verified through an illustrative example and simulation study.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.11
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• pp.483-490
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• 2006

When the nonlinearities, such as friction and backlash, are not considered in the controller design, undesirable oscillations can occur in the steady-state response of a control system. This paper deals with a method to reduce oscillations that often appear in the steady-state response of a pendulum system, which is controlled by a state feedback controller based on the linearized system model. With an assumption that the oscillations shown in the steady-state are caused by the Coulomb friction, we improve the performance of stabilization and tracking by estimating and compensating for the Coulomb friction in the pendulum system. Experimental results show that the control performance can be improved sufficiently by the proposed method, when it is applied to an inverted cart pendulum which is a multi-variable unstable system. Furthermore, we could see that the Coulomb friction model used in the estimation of the friction is valid in applying the suggested method.

• Smart Structures and Systems
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• v.24 no.2
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• pp.193-207
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• 2019

This study concerns with morphing structures, e.g. as applied in the aerospace industry. A morphing aerofoil structure capable of variable geometry was developed, which was shown to be able to cater for the different aerodynamic requirements at different stages of flight. In this work, the useful and relatively simple method has been applied, which provides a direct method for calculating required morphing shape displacements via finding the most effective bar through calculating bar sensitivity to displacement and calculating set of length actuations for bar assembly to control/adjust shape imperfection of prestressable structural assemblies including complex elements ("macro-elements", e.g., the pantographic element), involving Matrix Condensation. The technique has been verified by experiments on the physical model of an aerofoil shaped morphing pantographic structure. Overall, experimental results agree well with theoretical prediction. Furthermore, the technique of multi-iteration adjustment was presented that effective in eliminating errors that occur in the practical adjustment process itself. It has been demonstrated by the experiments on the physical model of pantographic morphing structure. Finally, the study discusses identification of the most effective bars with the objective of minimal number of actuators or minimum actuation.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.1
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• pp.69-78
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• 2011

In this study, an optimization method using multi-objective genetic algorithm(MOGA) has been proposed to develop a fuzzy control algorithm that can effectively control a smart tuned mass damper(TMD). A 76-story benchmark building subjected to wind load was selected as an example structure. The smart TMD consists of 100kN MR damper and the natural period of the smart TMD was tuned to the first mode natural period of the example structure. Damping force of MR damper is controlled to reduce the wind-induced responses of the example structure by a fuzzy logic controller. Two input variables of the fuzzy logic controller are the acceleration of 75th floor and the displacement of the smart TMD and the output variable is the command voltage sent to MR damper. Multi-objective genetic algorithm(NSGA-II) was used for optimization of the fuzzy logic controller and the acceleration of 75th story and the displacement of the smart TMD were used as objective function. After optimization, a series of fuzzy logic controllers which could appropriately reduce both wind responses of the building and smart TMD were obtained. Based on numerical results, it has been shown that the control performance of the smart TMD is much better than that of the passive TMD and it is even better than that of the sample active TMD in some cases.

• Journal of the Korean Solar Energy Society
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• v.36 no.6
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• pp.1-12
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• 2016

A control algorithm for a 100 kW wind turbine is designed in this study. The wind turbine is operating as a variable speed variable pitch (VSVP) status. Also, this wind turbine is a permanent magnet synchronous generator (PMSG) Type. For the medium capacity wind turbine considered in this study, it was found that the optimum tip speed ratios to achieve the maximum power coefficients varied with wind speeds. Therefore a commercial blade element momentum theory and multi-body dynamics based program was implemented to consider the variation of aerodynamic coefficients with respect to Reynolds numbers and to find out the power and thrust coefficients with respect tip speed ratio and blade pitch angles. In the end a basic power controller was designed for below rated, transition and above rated regions, and a load reduction algorithm was designed to reduce tower vibration by the nacelle motion. As a result, damage equivalent Load (DEL) of tower fore-aft has been reduced by 32%. From dynamic simulations in the commercial program, the controller was found to work properly as designed. Experimental validation of the control algorithm will be done in the future.

• Journal of Welding and Joining
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• v.28 no.4
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• pp.26-32
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• 2010

The purpose of this study is to evaluate the residual stresses at the multi-pass FCA weldment using the finite element analysis (FEA). In order to do it, an H-type specimen was selected as a test specimen. The variable used was in-plane restraint intensity. The temperature distribution at the multi-pass FCA butt weldment was evaluated in accordance with the relevant guidance recommended by the KWJS. The effective conductivity for the weld metal corresponding to each welding pass was introduced to control the maximum temperature below the vaporization temperature of weld metal. The heat flux caused by welding arc was assumed to be applied to the weld metal corresponding to welding pass. With heat transfer analysis results, the distribution of transverse residual stresses was evaluated using the thermo-mechanical analysis and compared with the measured results by XRD and uniaxial strain gage. In thermo-mechanical analysis, the plastic strain resetting at the temperature above melting temperature of $1450^{\circ}C$ was considered and the weld metal and base metal was assumed to be bilinear kinematics hardening continuum. According to the comparison between FEA and experiment, transverse residual stresses at the multi-pass FCA butt weldment obtained by FEA had a good agreement with the measured results, regardless of in-plane rigidity. Based on the results, it was concluded that thermo-mechanical FE analysis based on temperature distribution calculated in accordance with the KWJS’s guidance could be used as a tool to predict the distribution of residual stress of the multi-pass FCA butt weldment.

• Water for future
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• v.18 no.3
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• pp.225-233
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• 1985

To develop a simulation strategy of multi-reservoir operation in flood season, the single dam operations methed for the Chungju dam are investigated in the Han river basin. Thus, spillway rule curve, rigid ROM, and linear decision rules are applied for control operations, subject to the restrictions imposed by the river and the reservoir characteristics. The storage and release and control/utility efficiencies for several floods are calculated. The variation of control coefficients with respect to the return period are also examined. As the results of this comparative study, the optimal operation method can be selected in terms of the magnitude of flood. With inflow forecasting, the flood control operation can be greatly improved by variable coefficients rigid ROM and linear decision rules.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.404-407
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• 2009

The field oriented control of induction motors is widely used in high performance applications. However, detuning caused by parameter disturbance still limits the performance of these drives. In order to accomplish variable speed operation conventional PI-like controllers are commonly used. These controllers provide limited good performance over a wide range of operation even under ideal field oriented conditions. This paper is proposed adaptive fuzzy controller(AFC) and artificial neural network(ANN) based on the vector controlled induction motor drive system. Also, this paper is proposed control of speed and current using fuzzy adaptation mechanism(FAM), AFC and estimation of speed using ANN. The proposed control algorithm is applied to induction motor drive system using FAM, AFC and ANN controller. Also, this paper is proposed the analysis results to verify the effectiveness of this controller.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.12
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• pp.1870-1883
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• 1993

In this paper, in order to build up the User Network Interface based on ATM, a study on traffic control techniques which should be performed by main function groups-B 75,5 NT2, LEX-is discussed. The structure of B-NT2 which is the most important function group In the User Network Interface is defined in quite a simple manner in addition, the functional blocks of LEX are defined in a similar manner as those of B NT2. It is possible to distribute total traffic control functions by using the similarities between B-NT2 and LEX and by allocating virtual path identifiers fixedly according to the characteristics of the traffics. For the traffic control techniques of ATM, relations among Connection Admtsslon Control, Usage Parameter Control and Bandwidth Allocation Control are defined and Multi Rule Base structure to realize optimal control functions according to the characteristics of the source traffics is proposed. And the Real-time Variable Window algorithmsimply designed to be suitable for the Multi Rule Base architecture is also proposed. The performances of the proposed algorithm are analyzed through the computer simulation by generating on-off source traffic in a virtual system that has the form of the proposed hardware. The analyzed results show that the distributed control is possible and that the implementation of the proposed architecture and algorithm is possible.