• Advances in robotics research
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• v.1 no.1
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• pp.61-79
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• 2014

This paper presents theoretical and experimental investigations into the dynamic modelling and characterisation of a two-link flexible manipulator incorporating payload. A planar two-link flexible manipulator that moves in a horizontal plane is considered. A dynamic model of the system is developed using a combined Euler-Lagrange and assumed mode methods, and simulated using Matlab. Experiments are performed on a lab-scaled two-link flexible manipulator for validation of the dynamic model and characterisation of the system. Two system responses namely hub angular position and deflection responses at both links are obtained and analysed in time and frequency domains. The effects of payload on the dynamic characteristics of the flexible manipulator are also studied and discussed. The results show that a close agreement between simulation and experiments is achieved demonstrating an acceptable accuracy of the developed model.

• Journal of KSNVE
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• v.6 no.2
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• pp.187-196
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• 1996

A new control strategy to actively control the vibration of a very flexible single link manipulator is proposed and experimentally realized. The control scheme consists of two actuators; a motor mounted at the beam hub and a piezoceramic bonded to the surface of the flexible link. The control torque of the motor to produce a desired angular motion is firstly determined by employing a sliding mode control theory on the equivalent rigid dynamics. The torque is then applied to the flexible manipulator in order to activate the commanded motion. During the motion, underirable oscillation is actively suppressed by applying a feedback control voltage to the piezoceramic actuator. Consequently, the desired tip position is favorably accomplished without vibration. Measured control responses are presented in order to demonstrate the efficiency of the proposed control methodology.

• Journal of Distribution Science
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• v.14 no.1
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• pp.59-66
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• 2016

Purpose - The purpose of this study is to find out how shipping company recognizes making partnership with the third party logistics provider and to give implication. Research design, data and methodology - Personal interview and questionnaire by E-mail, Fax, Mail, and telephone were used. 700 copies of the questionnaires were distributed and 155 copied were returned. Among collected questionnaires, 20 copies were excluded because of insufficient content, and therefore 135 copies were used. Results - Korea should change into new paradigm from old one based on current economic and social systems which has stemmed from bureaucracy, inflexibility chauvinism and equalitarianism. Flexible policies, administration and systems will be needed for better business practices. The Domestic logistics corporation needs to preoccupy strategic logistics hub and network. Conclusions - To be a center of North East Logistics, Korea needs more reasonable business law, systems and policies. Social norms and orders should be established to accomplish political and social security. A paradigm of the policy ruling over development of capital city and satellite cities shall make change.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.600-605
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• 1989

A theoretical study is presented for the end-point holding control of a one-link flexible arm, whose base is subjected to a lateral fluctuation. The arm is clamped on a rigid hub mounted directly on the shaft of d.c. servomoter. The tip position is measured by a gap sensor fixed in space isolated from the system vibration. The arm is controlled so as to make the end point stay precisely at its initial position even if the base is fluctuated.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.29B no.1
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• pp.58-66
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• 1992

This paper proposes a neuro-controller for position control of one-link flexible robot arm. Basically the controller consists of a multi-layer neural network and a conventional PD controller. Two controller are parallelly connected. Neural network is traind by the conventional error back propagation learning rules. During learning period, the weights of neural network are adjusted to minimize the position error between the desired hub angle and the actual one. Finally the effectiveness of the proposed approach will be demonstrated by computer simulation.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.14 no.4
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• pp.31-37
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• 2006

In this paper, an experimental study on the robust input shaping for control of the residual vibration of flexible structures has been investigated. Two approaches has been used for the robustness of input shaping: the first method is to increase the number of impulses, and the other includes an EI shaper using vector diagram. The input case designed by the application of the above methods has been applied to a control problem involving residual vibration of a rotating hub with two flexible appendages. It has been found by a series of experiments that the input shaper designed in this paper works well for the residual vibration control of the flexible structure.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.280-284
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• 1997

In this paper, Nonlinear VSS control based on bang-bang control concept is derived under the assumption that the control input is bounded. We try to derive control algorithm which has almost same performance as the time optimal control. We focus this control scheme on the real implementation of DC motor position controller of flexible link, i.e. we obtain the switching curves from the real data of DC motor system operating under the full maximum and minimum applied voltages. State space is separated into several regions and we set different switching surfaces in each region to reduce chattering problem. The efficiency of the proposed controller is compared with PID controller and it is shown that the controller converges fast than PID controller without chattering. The hybrid controller scheme is also proposed not only to control the position of hub but also to reduce the vibration of end tip of flexible link.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.2
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• pp.200-206
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• 1991

In this paper, an output feedback is used to reduce the effect of the vibration in the control of a flexible one-link robot arm. A PD control method with a time varying gain is proposed to improve the performance of the system in tip deflection and settling time for the step reference input. By making the change of feedback gain smoothly, th input torque can be made smooth. When there is a payload with unknown mass, an interpolation method which uses the inrehgrated value of the transient response of the hub angle is proposed for the estimation of teh payload mass. This method can be used when the reference input is known and we can get highly accurate estimate for the unknown payload. It is also demonstrated that flexible one-link arm can be controlled prettry accurately by an output feedback in a noisy environment without knowing the mass of the payload.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1489-1495
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• 2012

In this study, we perform the structural analysis of a floating offshore wind turbine tower by considering the dynamic response of the floating platform. A multibody system consisting of three blades, a hub, a nacelle, the platform, and the tower is used to model the floating wind turbine. The blades and the tower are modeled as flexible bodies using three-dimensional beam elements. The aerodynamic force on the blades is calculated by the Blade Element Momentum (BEM) theory with hub rotation. The hydrostatic, hydrodynamic, and mooring forces are considered for the platform. The structural dynamic responses of the tower are simulated by numerically solving the equations of motion. From the simulation results, the time history of the internal forces at the nodes, such as the bending moment and stress, are obtained. In conclusion, the internal forces are compared with those obtained from static analysis to assess the effects of wave loads on the structural stability of the tower.

• Structural Engineering and Mechanics
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• v.22 no.2
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• pp.151-167
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• 2006

A p-version of the finite element method in conjunction with the modeling dynamic method using the arc-length stretch deformation is considered to determine the bending natural frequencies of a cantilever flexible plate mounted on the periphery of a rotating hub. The plate Fourier p-element is used to set up the linear equations of motion. The transverse displacements are formulated in terms of cubic polynomials functions used generally in FEM plus a variable number of trigonometric shapes functions representing the internals DOF for the plate element. Trigonometric enriched stiffness, mass and centrifugal stiffness matrices are derived using symbolic computation. The convergence properties of the rotating plate Fourier p-element proposed and the results are in good agreement with the work of other investigators. From the results of the computation, the influences of rotating speed, aspect ratio, Poisson's ratio and the hub radius on the natural frequencies are investigated.