• Proceedings of the KSME Conference
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• 2008.11a
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• pp.917-922
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• 2008

In order to reduce energy consumption, secondary controlled system has been applied to many types of equipments. In lifting equipments or press machines using hydraulic cylinder, a hydraulic transformer is used as a control component instead of a valve for motion control and a component for recovering potential energy of load. The transformer is combination of a variable displacement pump/motor as a secondary controlled element and a fixed displacement pump/motor. Based on the nominal model derived from mathematical model, the feedback type two-degree-of-freedom controller is designed and implemented. From simulation results, the disturbances including nonlinear friction torque, leakage flow and load force can be compensated and good positioning accuracy is obtained. It show that the proposed controller is effective.

• Smart Structures and Systems
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• v.19 no.5
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• pp.463-472
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• 2017

In a previous study, the potential of damping suspension bridges with active stay cables has been evaluated on a numerical model of a suspension bridge, and demonstrated experimentally on a laboratory mockup. In this paper, we extend our study to explore two different configurations of the active stay-cables: one classical configuration, corresponding to attaching the active stay-cables between the top of the pylons and the deck (configuration I) and, another configuration, consisting of attaching the stay-cables between the base of the pylons and the catenary (configuration II). The analysis confirmed that both configurations are effective with a slight superiority of the second configuration. The study is conducted numerically and experimentally on a suspension bridge mock-up, by considering two types of active stay-cables. The experimental results confirmed the numerical predictions, and demonstrated the effectiveness of the second configuration.

• 연구논문집
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• s.26
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• pp.85-94
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• 1996

The purpose of this study is to bring out the optimal design factors which effect on dynamic characteristics in the design of proportional flow control valve with high response characteristics, and to verify the validity of the design factors. In this study, force feedback type flow control valve with nozzle-flapper is studied. And, the influences which fixed orifice, nozzle diameter, and maximum displacement between nozzle and flapper effect on dynamic characteristics are analyzed. We have done simulations using the optimal design factors and simulink(Matlab) as a simulation tool, and verified the validity of our simulations by means of comparison our simulation results with an experimental results of another similar valve.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1642-1647
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• 2003

The market of the horizontal axis washing machine (drum washing machine) has been growing drastically in Korea by about 80% annually since 2000. As market grows fast, the customerTs demands concerning quality becomes more strict and various. Imbalance sensing is a key technology to reduce the NVH problem in a washing machine, because the laundry is time-variant and uncontrollable source of imbalance, which can cause more than 200kgf exciting force. In this paper, imbalance-sensing methods are briefly reviewed, new acceleration sensing circuits are examined, and finally the control algorithm of spinning process is proposed and validated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.1053-1057
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• 1996

The purpose of this study is to bring out the optimal design factors which effect on dynamic characteristics in the design of proportional flow control valve with fast response characteristics, and to verify the validity of the design factors In this study, force feedback type flow control valve with nozzle-flapper is studied. And, the influences which fixed orifice, nozzle diameter, and maximum displacement between nozzle and flapper effect on dynamic characteristics are analyzed. We have done simulations using the optimal design factors and simulink(Matlab) as a simulation tool, and verified the validity of our simulations by means of comparison our simulation results with an experimental results of another similar valve.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.741-744
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• 2002

The closed circuit pump is applied to control rotating speed and direction of hydraulic motor in hydrostatic transmission. To development of this pump, first of all the servo control regulator has to be designed. Mechanical-hydraulic type servo control mechanism is excellent to be compared with electronic-hydraulic type servo control valve to reliability and economy. In this paper to development positive and negative variable displacement type servo regulator, the hydro-mechanical servo control mechanism is calculated and designed with force balance of pilot piston and position feedback of servo piston.

• Korean System Dynamics Review
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• v.1 no.1
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• pp.133-157
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• 2000

This paper deals with the social system from the point of system thinking consisting the fundamental construct of system dynamics. The Bertalanffy's general system theory, having been criticized because of its ambiguity, and the complex science theory, emerging system theory, are integrated by using the system thinking which is characterized with three concepts, 'feedback thinking', 'dynamic thinking', 'operational thinking'. In the integration, system thinking suggests the dynamic pattern of the social system have not only an equilibrium status but also complex status. The science of complexity gives an implication to system dynamics the important of the uncertainty and complexity if we interpret the social system as an open system. To show more concrete description, I simulate the cooperation model based on the iterated prisoner dilemma. The simulation results show the diverse patterns of cooperation and betrayal. Especially the sensitivity of initial payoff will cause the chaotic strategic landscapes as the game gose on. These results mean that we should not give the hasty prescription to control social system artificially. Because social system retains the self-organizing force in itself.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.273-277
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• 1988

This paper is to show design of robot manipulator which has 3-link using DC Motor and realization of control algorithm with IBM - XT Micro-computer connected. Gentral algorithm is applicated by position and pass control using point-to-point method. At first, this paper computes required angles on each joint in order to search desired position or path, and uses a voltage control with feedback from output of encoder and tachometer in real time. The application of control algorithm on position, velocity and force for each joint of manipulator by using self-tuning control is left for next study.

• The Journal of Korean Physical Therapy
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• v.11 no.3
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• pp.13-21
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• 1999

Active movement is able to actively contract his muscles and move a segment either with or without assistance. This movement maintain physiologic elasticity and contractility of the participating muscles, provide sensory feedback from the contracting muscles and stimulus for bone integrity as well as increase circulation and prevent thrombus formation, in addition to develop coordination and moor skills for functional activities. Passive movement is the motion to the external force; gravity, machine, another individuals. Active movement is more activated rather than passived on the central nervous system. Therefore, we think that active movement is more effected facilitating through specific inhibitory mobilization of muscle.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.62-69
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• 2002

With the development of CUP speed and graphic technology, real-time simulation of deformable object is embossed as an essential issue in engineering field. Recently, it has been applied to the surgical training and game animation with haptic force feedback. But real time simulation of deformable objects is not easy because of the conflicting demands of speed and low latency and physical accuracy. In this study, we present the implementation of boundary element method(BEM) which is combined with the nonuniform B-spline surface. It is working together with the real-time simulation technique and the geometry data is altered by handling control points without preprocessing routine.