• Journal of Advanced Marine Engineering and Technology
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• v.27 no.5
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• pp.590-599
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• 2003

In this study. object transport method based on ultrasonic flexural vibration is presented. Ultrasonic vibration generates ultrasonic traveling waves on the surface of elastic medium. Objects are transported through the interaction with traveling waves propagating in medium. Two types of transport methods are studied： frictional drive and acoustic levitation. With frictional drive, objects are transported in contact with the beam in the opposite direction of wave propagation whereas with acoustic levitation, objects are acoustically levitated above the beam surface and transported in the wave propagation direction. Transport characteristics are experimentally investigated using objects of different shapes and sizes. The transition from acoustic levitation mode to frictional drive mode is also examined. and it is found to occur when the ratio of mass to area of an object exceeds the threshold ratio of mass to area. It is envisaged that this feasibility study will serve as a stepping-stone for ultrasonic vibration to become an effective industrial material handling device in the future.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.570-575
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• 2002

Servo performance of a disk drive is greatly affected by the mechanical resonance frequencies of the head gimbal assembly (HSA). It is important factor to allow broader bandwidths for servo system in improving overall drive performance. In this paper, an optimal design for ODD suspension is attempted to increase resonance frequencies in tracking direction. Initial model was designed and the design parameter was defined to the model. The mode frequency variation for the change of design parameter was observed by modal analysis using the finite element method(FEM). The sensitivity matrix was calculated from the observed data and so through sensitivity analysis, an optimized ODD suspension was designed to have the higher resonant frequency than the initial model.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.31-36
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• 2002

Even through the problem of misalignment is of great importance, not much work has been reported in the literature on the effect of misalignment on the vibrations of the gear-bearing systems. Therefore, the nonlinear dynamic characteristics of the gear drive system due to misalignment are investigated in this work. Transmission error for helical gear and bearing nonlinear stiffness is calculated. The equation of motion of the gear drive system is modelled using the time-varying gear meshing stiffness, bearing nonlinear stiffness, and bearing pre-load due to the housing deformation. Numerical analysis lot the gear drive system show the result of misalignment effect - sub-harmonic component, bearing pre-load effect, and another nonlinear phenomenon. And the numerical analysis are verified by the experimental result.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.6-10
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• 2004

This paper newly proposes the SRM drive system based on DC-link current information, from which the phase currents can be estimated in accuracy and also they can be used in driving SRM instead of the phase currents. Comparing to the general drive system based on the phase current information, it is verified through the simulation(which are peformed by RMxprt and Simplorer) that the proposed SRM drive system has the good performance in dynamic and steady-state responses of the speed control. Using the DC-link current information, all of the multi-phase currents can be easily estimated in driving the SRM.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.11
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• pp.1033-1038
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• 2000

The unbalanced heavy-loaded elevation-drive system is composed of a hydraulic cylinder, a driving link-mechanism and an equilibrating-mechanism which compensate the static unbalanced moment of the elevation load. The Compensator for the unbalanced moment is composed of a hydrau-pneumatic accumulator and a hydraulic cylinder which act with the elevation cylinder together. Compensation of the variable static-unbalanced moment for the elevation-drive system is very difficult because these mechanisms imply highly nonlinear properties due to air conditioning characteristics and mechanical rotation of the link-mechanism. In this study, through the analysis of the already designed equilibrating-mechanism, the optimal design parameters of the equilibrating-mechanism is suggested.

• Journal of Electrical Engineering and information Science
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• v.3 no.1
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• pp.58-66
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• 1998

A continuous, accurate, and robust variable structure tracking controller(CVSTC) is designed for brushless direct drive servo motors(BLDDSM). Although conventional variable structure controls can give the desired tracking performances, there exists an inevitable chattering problems in control input which is undesirable for direct drive systems. With the presented algorithm, not only the chattering problems are removed by using the efficient compensation of the disturbance observer, but also the prescribed tracking trajectory can be obtained using the sliding dynamics when an initial of the desired trajcetory is different from that of a BLDDSM. The design of the sliding mode tracking controller for the prescribed, accurate, and robust tracking performance without the chattering problem is given based on the results of the detailed stability analysis. The usefulness of the suggested algorithm is demonstrated through the computer simulation for a BLDDSM under load variations.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10b
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• pp.1014-1017
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• 1988

Direct-drive robots have excellent features including no backlash, small friction, and high mechanical stiffness. However, dynamic coupling among joints as well as nonlinear effects become more prominent than traditional robots with reducers. Another critical issue is that the robot becomes more sensitive to the change of load. In this paper, we develop a simple current feedback scheme for reducing the influence of dynamic coupling and load sensitivity on the direct-drive robots. The method is implemented on a 2 d.o.f. planar direct-drive robot. Then the validity of the method is demonstrated through experiments.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.195-198
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• 2000

It can be acquired the high effective productivity through of high speed, precision of machine tools, and then, machine tools will be got a competitive power. Industrially advanced countries already developed that the high speed feed is 60m/min using the high speed ball screw. Also, a lot of problems have happened the feed drive system. It is necessary to study about the characteristics of thermal deformation played a more critical role than static stiffness and dynamic rigidity in controlling the level of machining accuracy. In spite of the improving the thermal deformation characteristics of machine tools at the design stage, there are always some residual errors that have to be compensated for during machining. In this study, thermal deformation error automated compensation device with multiple linear regression is proposed that thermal deformation error can be eliminated at the machining stage. The developed device has been practically applied to the feed drive unit.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.263-268
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• 1997

Development of a high speed feed drive system has been a major issue for the past few decades in machine tool industries. The reduction of tool change time as well as repid travel time can enhance the productivity. However,the high speed feed drive system generates more heat in nature,which leads to thermal expansion that has adverse effects on the accuracy of machined part. The paper divides the feed drive system into the ball screw and guide way. For each part, the thermal behvior model is separtately developed to estimate the position error of the respective feed drive system that is caused by the thermal expansion. The modified lumped capacitance method is used to analyze the linear position error of the ball screw. The thermal deformation of guide way parts affects the straightness and angular error as well as linear position error. Finite element method is used to estimate the thermal behavior of these guide way parts. The effectiveness of the proposed models are verified through the experiments using laser interferometer.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.6
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• pp.508-512
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• 2013

In recent years, sensorless drive schemes have been proposed widely and most of them are based on the ZCP (Zero Crossing Point) detection of the BEMF (Back Electro-Motive Force). These schemes have two main problems. One is that ZCP may not be detected at low speed and thus a forced drive is required. The other problem is that there is $30^{\circ}$ phase difference between ZCP and the motor commutation instant and to ensure proper operation, this gap should be accounted for. To solve these problems a circuit is devised for detecting ZCP of the BEMF difference through the line voltage difference. Experimental results show that the output of this circuit is identical to that of the Hall sensor signal, and velocity control of a BLDC motor is possible without the sensor.