• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.12 no.1
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• pp.21-25
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• 2006

Measurements of accelerometer levels transmitted from the floor in commercials truck shipments were carried out transportation of 300 Kg-load from Gyungbu Highway(Waegouan-Seoul) to 88 Highway(Gwangju-Daegu). Different characteristics were observed the values measured the vibration levels with directions in the two Highway's as a function of road condition and truck speed. The results showed that the vibration levels of the Gyungbu Highway is much higher than those of the 88 Highway. A following analysis on the obtained values was used to get the acceleration spectral density (ASD) and power spectral density (PSD). For the entire transit route, the results showed that the level of vibration to vertical direction was significant effects for damaging the products carried compared to other directions such as longitudinal and transverse. This paper provides an updated history of measured characteristics of vibration levels for highways using mainly in domestic area.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.829-832
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• 2002

With the increase of storage density, high rotational speed and high access technologies in optical disk drive, mechanical issues, mainly noise and vibration, become critical. Up to now the researches of rubber mount for anti-vibration focused on how to calculate the static and the dynamic stiffness of rubber mount and leaved out of consideration of the dimensional tolerance of rubber mount for anti-vibration. This paper presents the effects of dimensional tolerance of rubber mount for anti-vibration on the dynamic characteristics of optical disk drive by finite element analysis and dynamic test. The relation between dimensional tolerance and dynamic characteristics of optical disk drive is observed and discussed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.10
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• pp.751-759
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• 2003

The theoretical method is developed to investigate the vibration characteristics of the sloshing and bulging mode for the circular cylindrical storage tank with an annular plate on free surface. The cylindrical tank is filled with an inviscid and incompressible liquid. The liquid domain is limited by a rigid cylindrical surface and a rigid flat bottom. As the effect of free surface waves Is taken into account in the analysis, the bulging and sloshing modes are studied. The solution for the velocity potential of liquid movement is assumed as a suitable harmonic function that satisfies Laplace equation and the relevant boundary conditions. The Rayleigh-Ritz method is used to derive the frequency equation of the cylindrical tank. The effect of Inner-to-outer radius ratio and thickness of annular plate and liquid volume on vibration characteristics of storage tank is studied. The finite element analysis is performed to demonstrate the validity of present theoretical method.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.9
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• pp.422-430
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• 2001

An electric drill is a handy tool used in a machine shop, which consists of motor, gear, bearing, shaft, and case, i.e., a gear driving system. Low level vibration and noise of the electric drill can bring the assurance of the quality and reliability of the machine. The vibration sources of the electric drill should be investigated for the reduction of the vibration and noise of the system. Through the experiments in laboratory and the various signal processing procedure for the measured vibration and sound signals, the characteristics of the vibration of the electric drill are investigated. And its propagation path is sought using partial coherence function.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.10
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• pp.1742-1756
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• 1997

The acoustic characteristics of a direct radiator type loudspeaker has been studied in this paper. The natural modes of the speaker cone vibration analyzed numerically by the finite element method have been verified by comparing them with experimental results. The so-ap-proved finite-element model has been used to calculate the vibration response of the cone excited by the voice coil. The vibration displacement of the speaker cone paper has been converted into the vibration velocity and used as a boundary condition for the acoustic analysis. The frequency characteristics, directivity, and sound pressure distribution of the loudspeaker have been calculated by the boundary element method. The numerical results have been verified by the experiments carried out in an anechoic chamber. The variations of the acoustic characteristics due to the changes of some design parameter values can be examined using the numerical model.

• Journal of the korean Society of Automotive Engineers
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• v.12 no.4
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• pp.47-55
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• 1990

This study is the first step for the grasp of transfer path to the vibration generated from the automotive engine and consideration of counterplan for optimal design and low vibration, low noise of the exhaust system. In this study, by applying the theory of modal analysis and experiment, vibrational reduction effect is evaluated according to the attachment of flexible coupling to the exhaust system. And data for the design is suggested to improve the characteristics of vibration. The vibration isolation and damping characteristics are improved due to the attachment of flexible coupling to the exhaust system. As a result, it is identified that flexible coupling which has good flexibility is more effective for the improvement of vibrational characteristics. By the estimation of modeshape of vibration, the location of optimal damping hanger is determined in the viewpoint of vibration isolation. Also it is confirmed that the characteristics of vibration is improved due to the attachment of damping hanger.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.682-686
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• 2001

A fundamental structural design consideration for a vehicle is the overall vibration characteristics in bending and torsion. Vibration characteristics of a vehicle system are mainly influenced by dynamic stiffness of the vehicle body structure and material and physical properties of the components attached to the vehicle body structure. The first step in satisfying this requirement is to obtain a satisfactory dynamic model of the vehicle structure. In this paper. modeling techniques of the vehicle components are presented and the effects of the vehicle components on the vibration characteristics of the vehicle are investigated,

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.3
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• pp.274-280
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• 2004

This paper presents the analysis fur the radial vibration characteristics of cylindrical piezoelectric transducers. Taking into account the piezoelectric anisotropy, the differential equations of piezoelectric radial motion have been derived in terms of radial displacement and electric potential. Applying mechanical and electric boundary conditions has yielded a characteristic equation for radial vibration. Numerical analysis also has been carried out by using the finite element method. Theoretical calculations of the fundamental natural frequency have been compared with the experimental observations for transducers of several sizes. Comparison with the previous report of theoretical analysis simplifying the piezoelectric anisotropy into isotropy concludes that isotropic analysis is a reasonable process to predict the vibration characteristics of piezoelectric transducers.

• Journal of the Korean Society for Railway
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• v.6 no.3
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• pp.186-193
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• 2003

The object of this study is to ensure the stability of bulk cement cars conducting vibration performance test, dynamic characteristic analysis and static load test of bogie frame. In case of static load test, bogie static load test facility was used. In case of dynamic characteristic analysis, Vampire Software was used. In case of vibration performance test, real bulk cement cars were used in kyeung-bu line. In the results of static load test of bogie frame for bulk cement car, all structures satisfied allowable stress criteria of materials. The vibration performance test and dynamic characteristic analysis results satisfied allowable standards.

• Journal of the Korean Society for Railway
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• v.3 no.2
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• pp.51-61
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• 2000

In this study, field measurements of vibration on the structures supporting railroad track were performed. The vibration data obtained were analyzed to find out any correlation between its magnitude and several factors such as type of bridges, distance from the track, type of train, frequency characteristics, etc. As a result, the magnitude of vibration turned out to be the highest in the steel bridge, the concrete bridge and steel-concrete combined bridge were the next in descending order. It was also found that the dynamic characteristics of ground were the most important factors among several affecting vibration near by the railroad track. And the empirical ground vibration estimation equation for estimating ground vibration was developed. The proposed equation with respect to distances from the railroad could be easily used for the estimation of ground vibration at the residential areas nearby the track.