• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.9-11
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• 1999

This paper presents the problems of design and theoretical model of electrostatically driven axial-gap type wobble motor. The motor design benefits from large axial rotor-to-stator overlap and large gear ratios, and motor designs with rotor radii of 50 and $100{\mu}m$ are capable of generating torques in the [nNm] range at high electrostatic fields. Because of the large gear ratio, smaller angular steps and lower rotational speed are obtained, compared to radial-gap motor design. Aspects like gear ratio, torque generation, excitation schemes and torque coverage, normal forces, friction are addressed.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.3
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• pp.105-109
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• 2001

In this paper, the windmill type ultrasonic motors with 11.35 mm diameter, 2.87 mm thickness of metal endcap and 1.47 g weight were fabricated. Effects of slots and thickness on torque characteristic in the windmill type ultrasonic motor were investigated, when stator's slots were changed from 4, 6, 8 and thickness 0.15 mm, respectively. Specially designed metal endcaps with windmill shaped cutting can provide longitudinal and torsional displacements simultaneously as the ceramic disk vibrates radically. The windmill type ultrasonic motor has only three components: a stator element with windmill shape slotted metal endcap, a rotor and bearing. Ultrasonic motor stimulated to ultrasonic oscillations by piezoelectrics to drive a rotor via friction contact. The ultrasonic motor fabricated here was the windmill type ultrasonic motor operated by single-phase AC source. Bidirectional revolution using single-phase high frequency for driving the ultrasonic motor was presented.

• Journal of the Semiconductor & Display Technology
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• v.18 no.1
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• pp.25-31
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• 2019

In this study, a new adhesion evaluating equipment and data processing methods were developed to overcome some limitations of existing evaluating equipment. Nano-diamond coated tool is a specimen of experiment. When applying frictional force and shear force on the specimen by a rotating polishing pad, delamination occurs at a moment. During each experiment, the vibration, load, and torque is obtained by accelerometer, loadcell and torque s+ kpensor. Frictional force and coefficient of friction are obtained by calculating torque and load. Based on FFT transformation, acceleration is processed and analyzed. As a result, the moment of delamination and the load at that time can be detected by the new developed equipment and measurement system. Finally, we call this load as an Adhesion force.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.103-104
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• 2009

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1996.04b
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• pp.68-72
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• 1996

본 연구에서는 에어오일 윤활하의 고속용 앵귤러 콘택트 볼베어링에 있어서, 여러 축방향의 하중과 윤활량의 변화에 대하여 회전속도에 따른 베어링의 마찰 토오크를 변화를 측정하고, 또한 회전속도, 하중 및 윤활량의 변화가 베어링 접촉부에서의 유막형성에 어떠한 영향을 미치는가를 알아보고자 한다.

• Transactions of The Korea Fluid Power Systems Society
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• v.4 no.1
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• pp.13-17
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• 2007

The brake gain adaptive wheel slip controller for a vehicle is designed in this paper. The brake gain from braking pressure to braking torque defined by friction coefficient, friction area and effective friction radius is estimated by the adaptive law based on the wheel slip dynamics. And the wheel slip controller is designed based on the estimated brake gain. The robustness of the designed controller is analyzed using Lyapunov function and the convergence of brake gain is verified. Proposed wheel slip controller is verified via CarSim simulation with two kinds of desired wheel slip ratio.

• Tribology and Lubricants
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• v.24 no.3
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• pp.133-139
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• 2008

In recently designed diesel engines, the running conditions for piston pin bearings have become very severe due to combustion pressure and temperature increase. In this paper, it will be investigated the tendency of piston pin rotating motion by calculating the friction coefficient at piston pin bearings, the oil film thickness and the frictional torques induced by hydrodynamic shear stress. Finally, the pressure distributions on the oil film of piston pin bearings will be found by two-dimensional lubrication analysis in order to help the optimum design of the bearings of piston pin. Specially, it is investigated the effects on the film pressure distribution due to the change in maximum combustion pressure.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.10
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• pp.1364-1369
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• 2002

This paper introduces the development of the analysis and design program of valve train system. In order to verify the stability of design and improve the performance of system efficiently, it is required that integrated and interactive simulation program. The presented program is developed in the base of the object-oriented, capsulation, modulization, OLE (objected linking and embedding) and various design theory. It contains the expandability and flexibility of the structure. In addition to that, it is programmed to make the convenient user interface by using the visualization programming. This program can support the modification of the valve element as well as the development of the valve train system in the beginning of design. It is expected to save the cost and time for the design of valve train system.

• Tribology and Lubricants
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• v.24 no.2
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• pp.55-62
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• 2008

In recently designed diesel engines, the running conditions for piston pin bearings have become very severe due to combustion pressure and temperature increase. In this paper, it will be investigated the tendency of piston pin rotating motion by calculating the friction coefficient at piston pin bearings, the oil film thickness and the frictional torques induced by hydrodynamic shear stress. Finally, the pressure distributions on the oil film of piston pin bearings will be found by two-dimensional lubrication analysis in order to help the optimum design of the bearings of piston pin. Specially, it is investigated how the changes in combustion pressure at exhaust and intake stroke and the pressure-viscosity index effect on the film pressure distribution.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.2
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• pp.44-50
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• 2006

A driver's feelings of transmission serve as a basis to judge not only the transmission but also the entire automobile that he or she drives. The importance of transmission feelings is increasing daily because of driver's desire for increased torque and other improved functions. In order to accommodate such desire of drivers, new friction materials have been developed. The study in this report compared the affects of such materials and the force for transmission theoretically and empirically. By doing so, the study attempted to establish basic references for computation of capacity and other factors to be determined at the time of design of synchronizer system.