• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1503-1507
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• 2003

A general vibration phenomenon of a rigid-body supported by springs can be viewed as a small repetitive screw displacement. From this view, a multi-directional vibration absorber can be designed by use of screw theory and transfer matrix method. In this paper, the basic equations of motion for a multi-body system have been expressed in terms of screws using transfer matrix method and a simple approach to the design of a multi-degrees-of-freedom absorber has been presented. In order to illustrate the methodology, an example for the design of a 2-DOF active absorber which is capable of absorbing vibration of a rigid body excited by 3-DOF external force has been presented.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.724-729
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• 2003

The prototype of Korean high speed train (KHST), composed of two power cars, two motorized cars and three trailer cars, has been designed, fabricated and tested by the domestic researchers. In this paper, the body vibration has been reviewed from the viewpoint of the vehicle's safety and the vibration limits for components and sub-assemblies mounted on the car-body using by the experimental method. The on-line test of KHST has been carried out up to 260 km/h in the KTX line and proved that KHST has no problems in the vehicle's safety and the vibration limits at this speed. And the characteristics of body vibrations has been predicted at 300 km/h and 350 km/h by fitting curve about the measured acceleration signals.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2519-2521
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• 2001

This paper presents an auxilary beam-assisted adaptive compensation technique applied to alleviate the problem of LDV's body vibration. The LMS algorithm is applied to adaptively compensate the body vibration utilizing the reference signal provided by the auxiliary beam. The usefulness of the proposed technique is verified computer simulations performed for diverse types of target signals and body vibration.

• Journal of the Korea Institute of Military Science and Technology
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• v.3 no.2
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• pp.15-22
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• 2000

Shock and vibration characteristics of a tractor-trailer type vehicle system with air suspension and air coupler running on a single bump road are investigated. The vehicle system is modelled and solved to two types of models, i.e. rigid-multi-body and flexible-multi-body model, by ADAMS and NASTRAN software. And the shock impulse is given by a single bump model on the road. When the analysis results of the rigid-multi-body model is compared with those of the flexible-multi-body model, it is revealed that the vibration and accelerations of the latter model are more repetitive and larger than the former.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.7
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• pp.267-274
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• 2001

This paper introduces experimental results related to the vibration ride conditions that a korean male subject experienced in the nationwide railway trains and the express bus. Two types of railway train's Saemaulho and Mugunghwaho. and the express bus were chosen to measure how much the whole-body vibrations on the contact area of the back , hip and feet are exposed to the subject. Measured vibration signals were analysed to assess the rife conditions quantitatively and qualitatively. Analysed results are illustrated to unveil how much typical public transportation system in Korea expose whole-body vibration to passengers. Futhermore, the performance evaluation of their seats were carried out to examine their effectiveness in reducing vibration exposure to passengers.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.8
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• pp.592-599
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• 2014

A torsional vibration at driveline happens seriously at rapid vehicle acceleration. The torsional vibration at driveline can be reduced by optimization of joint angle and yoke phase angle of driveline. But, the joint angle of driveline is changed according to vehicle driving condition as acceleration, deceleration, forward and backward driving, so that excessive vibration is transmitted to vehicle body at specific driving condition. Especially under rapid acceleration condition, vibration transmitted to body could be maximized because excitation force at rapid acceleration is bigger than that at normal driving condition due to changed joint angle. The torsional vibration of driveline can be kept at low level by controlling suspension parameter to minimize rigid axle displacement as well as optimizing joint angles considering the vehicle acceleration condition.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.925-930
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• 2004

This paper is to study vibration effects of the dynamic vibration absorber. Multi-body dynamic analysis is carried out for the vehicle driveline model using ADAMS with flexible propeller shaft attached with the vibration damper. Primary bending mode frequency of the propeller shaft is obtained from the simulation and coincides with the experimental result. Various design parameters are studied in dynamic simulation operated by the engine torque input. This paper identifies the responses of dynamic vibration absorbers in the driveline with propeller shaft, which will be used to find out optimal design parameters.

• Journal of KSNVE
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• v.7 no.2
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• pp.261-272
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• 1997

Recently washing machines are to be in lower vibration and lower sound because of better environment. Vibration problems in washing machines occur in both washing mode and spinning mode, but vibration in spinning mode becomes main problem because of its high rotating speed and continuity. Vibration while spinning is mainly due to rigid body motion of total washing system which includes suspending rods, washing bath, spinning bath, and gear sets. In this study, some researches were done in order to analyze the rigid body motion of washing system and flexible vibration of spinning bath. A basic mathematical model was established, and the effect of position of salt water and shape change of salt water case were considered. And the effect of lengths of suspending rods, attaching angles, vertical and horizontal position, stiffness of spring on the change of vibration were also considered. To identify the effect of salt water on vibration, some measurements were done. When salt water was positioned at upper part, the effect was most and this coincides with the tendency of simulation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.8
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• pp.626-631
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• 2002

A modified equation for the evaluation of discomfort of a seated human body exposed to differential vibration at the seat and the floor was proposed in this paper. Through the review and analysis of the preceding studies, effect of phase difference between the seat and the floor vibration on discomfort were quantitatively identified. The phase effect was shown to be governed by not only phase difference between the two vibrations but both their frequency and the magnitude, which means the present equation for the evaluation of perceptual amount of vibration provided by ISO 2631-1 should be modified. The proposed equation was developed such that the correction function was multiplied to the present equation. The correction function consisted of three parts, each of them represented the effect by phase difference, frequency and vibration magnitude on discomfort respectively.

• Journal of Biomedical Engineering Research
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• v.38 no.1
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• pp.49-55
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• 2017

The prevalence of obesity has noticeably increased worldwide over several decades with various complication. Even though anti-obesity drug treatments have been spotlighted by resulting in effective mean weight losses, its adverse effects cannot be overlooked. Thus, this study aimed to evaluate the effects of multi-frequency whole body vibration, one of the mechanical stimulus, as a countermeasure against obesity. Thirty-two-6-week-old C57BL/6J male mice were equally assigned to four groups: the Control group (CON, n = 8), the Sham group (Sham, n = 8), the sham with single frequency whole body vibration (S+V, n = 8), and the sham with multi frequency whole body vibration (S+MV, n = 8). After 4 weeks, morphologic changes in the adipose tissue were evaluated from three-dimensional images using in vivo micro-computed tomography. At 4 weeks, the volume of the abdominal adipose tissue, which had the highest value in Sham group, noticeably reduced in S+MV group compared to it in S+V group. These results implied that the accumulation of abdominal adipose tissue can be effectively reduced through applying multi-frequency whole body vibration.