• Journal of Applied Reliability
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• v.14 no.4
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• pp.236-242
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• 2014

Since permanent magnet coupling transfers power by magnetic force without contact, it has little shock, vibration, noise. In case of overload, it protects a pump or a motor which is relatively important by slipping internally. In this study, failure analysis and test evaluation on the permanent magnet coupling have been proposed and the process that reliability of the product improves through design improvement has been presented. And failure cause of typical failure case has been investigated and improvement plan has been presented. Finally, reliability improvement is established by analysis of the test results of before and after acceleration test.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.66-72
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• 2006

In this paper, an analytical investigation on the track separation mechanism for tracked excavator was studied. Relative motions of track links, sprocket, idler and support rollers are very important in the driving of an excavator The interference and friction between each components lead to noise and vibration. And also this has a great influence on the life for tracked excavator. RecurDyn program was used for the three dimensional modeling of the track assembly. Investigating the interference between sprocket and track links, the mechanism of the track separation was analyzed.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.77-82
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• 2001

The 3-lobes blower has been conventionally made by constructing the impeller with the cross-section of simple arc, and has several problems such as noise, vibration and the oscillation of torque. These are caused by the variation of clearance between both impellers rotating in geared. In the present study, an approach for the design of cross-section of impeller has been proposed to prevent the above problems. The whole cross-section is divided into the concave and convex part. The concave zone is designed by simple arc and the convex zone is modified by the condition that some part of convex zone is always in contact with the other impeller during rotating. A sample design has been carried out and it can be seen that the clearance between both impellers is always uniform and the validity of present work has been verified.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.2
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• pp.283-289
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• 2012

Cam rack pinion (CRP) system which consists of cam rack and roller pinion transforms the rotation motion into linear one. The roller pinion has the plurality of rollers and meshes with its conjugated cam rack. The exact tooth profile of the cam rack and the non-undercut condition to satisfy the required performance have been proposed by introducing the profile shift coefficient. The load stress factors are investigated by varying the shape design parameters to predict the gear surface fatigue limit which is strongly related to the gear noise and vibration at the contact patch. The results show that the pitting life can be extended significantly by increasing the profile shift coefficient.

• Journal of KSNVE
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• v.10 no.2
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• pp.269-279
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• 2000

This paper deals with the development of biomechanical model on a seat with backrest support in the vertical direction. Four kinds of biomechanical models are discussed to depict human motion. One DOF model mainly describes z-axis motion of hip, two and three DOF models describe z-axis of hip and head, and while nine DOF model suggested in this study represents more motion than the otehr model. Three kinds of experiments were executed to validate these models. The first one was to measure the acceleration of the floor and hip surface in z-axis, the back surface in x-axis, and the head in z-axis under exciter. From this measurement, the transmissiblities of each subject were obtained. The second one was the measurement of the joint position by the device having pointer and the measurement of contact position between the human body and the seat by body pressure distribution. The third one was the measurement of the seat and back cushion by dummy. The biomechanical model parameters were obtained by matching the simulated to the experimental transmissiblities at the hip, back, and head.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3246-3252
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• 1994

The vibration of meshing gear system is originated form teeth deformation, teeth contact ratio, profile error, etc. The gear vibration is classified as whine vibration during meshing and as rattle vibration during idling. In this study, the whine vibration is investigated under the assumption of piecewise linearity of elastic stiffness due to the variation of meshing. Numerical, theoretical and experimental investigations show the existence of the superharmonic components of the second and the third order. consistently It can be concluded that the superharmonic components in whine vibration of meshing gear is originated from the stiffness variation. It also shows that the higher order harmonics are reduced on the increase of motor speed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.43-47
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• 1995

The ball screw is one of the important mechanical parts for the linear motion feeding systems. The usage of the ball screw has been growing in various industrial fields such as CNC machine tool, industrial robot and automated systems. Because of ever increasing demand for ball screws, increased accuracy and quality of the ball screw is needed,especially the surface roughness of the ball contact area in order to diminish noise and vibration. Therefore to improve the surface roughness of the area,we introduced magnetic assisted polishing which is one of the new potential polishing methods. In this study, diamond slurry and iron powder was used for magnetic assisted polishing of the ball bearing surface. This polishing process was experimentally confirmed to improve the surface roughness of the ball bearing.

• Journal of KSNVE
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• v.11 no.2
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• pp.346-353
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• 2001

In this study dynamic characteristic of catenary system that supplies electrical power to KTX Korean high-speed trains are investigated. A simulation program based on 3-span and 6-span finite element models of the catenary is developed. The influences of the various design parameters on the dynamic responses of the catenary are determined. The main design parameters include tension on the contact and messenger wires and the stiffness of the droppers connecting the two wires. The vibrational responses are primarily determined by the reflections of the propagating wave, and the dropper stiffness is found to be the dominant factor that influences overall dynamic characteristics of the catenary.

• Journal of KSNVE
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• v.11 no.2
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• pp.315-322
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• 2001

This paper is focused on the frictionally induced thermoelastic instability (TEI) in automotive disk brakes. This instability leads to the formation of localized high temperature contact regions known as hot spots. This article investigates the themoelastic instability in automotive disk brake systems consisting of a finite thickness layer (disk) and two half-planes (pads) using a perturbation method. The antisymmetric mode involves hot spots located alternately on two sides of the disk. As a result the circumferentially periodic hot spots produce rotor surface distortion and Induce low frequency vibration. Also the effects of system parameters on the critical speed for TEI are investigated.

• Journal of KSNVE
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• v.5 no.4
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• pp.483-492
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• 1995

For evaluation of rotational accuracy performance of high speed machine tool spindle system, the characteristics of main spindle and tool motion behavior are presented by means of three point accuracy testing method. The results of experiments and analyses are as follows: (1) The high speed spindle rotational accuracy can be evaluated by the combination of the spindle and tool motion behavior. (2) The spindle motion behavior increases up to more that 4 times the tool motion behavior. (3) For the influence of oil viscosity on spindle and tool taper application, 32 cSt of oil viscosity showed the most satisfactory result for rotational accuracy. (4) In order to improve the rotational accuracy of high speed machine tool spindle system, it is needed to reduce the combination error. This can be achieved by improving the working accuracy and supplying the proper lubrication with contact area at the spindle and tool.