• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.11a
• /
• pp.984-987
• /
• 2003

This paper discusses the lateral vibration of a bar which has its tip free. The uniform bar has a solution by summation of some simple exponential functions. But if its shape is not uniform, its solution could be by Bessel's function, or mathematical solution could not be existed. Even if the solution of Bessel's function exists. as Bessel function is a series function, we must get the solution by numerical method, Hereof the author proposes the solution of the matrix method by Ritz's method, and proposes a new deflection shape

• Geomechanics and Engineering
• /
• v.2 no.1
• /
• pp.45-56
• /
• 2010

The current study presents a mathematical model and numerical method for free vibration of tapered piles embedded in two-parameter elastic foundations. The method of Discrete Singular Convolution (DSC) is used for numerical simulation. Bernoulli-Euler beam theory is considered. Various numerical applications demonstrate the validity and applicability of the proposed method for free vibration analysis. The results prove that the proposed method is quite easy to implement, accurate and highly efficient for free vibration analysis of tapered beam-columns embedded in Winkler- Pasternak elastic foundations.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2001.03a
• /
• pp.533-540
• /
• 2001

Material damping is an important parameter to evaluate the site response by a dynamic loading. Currently the material damping of the subgrade is mainly determined by a resonant column testing. Typical methods to evaluate material damping include half-power bandwidth method and free-vibration decay method. In the large strain range, the half-power bandwidth method gives an erratic damping factor, because the method is based on the assumption of the linear behavior of a specimen. The free-vibration decay method has also limitations in that the damping factors vary with the range of cycles in calculation, and also in that the specific shear strain can not be designated for the free vibration. In this study, the frequency-phase method, which was developed to evaluate material damping of a beam simply supported, is introduced to evaluate the material damping by the resonant column testing. Also, the comparison among half-power method, free-vibration decay method and the frequency-phase method is provided for a remolded sand.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.18 no.5
• /
• pp.564-571
• /
• 2008

This paper is concerned with the free vibration analysis of an annular plate with boundary conditions of simply supported-free, clamped-free and free-free, respectively. Exact solutions for the natural frequency and mode of an annular plate can be obtained by solving the differential equation but other methods such as the Rayleigh-Ritz method and the finite element method can be also used. In this research, we applied the Independent Coordinate Coupling Method(ICCM) to the annular plate and prove that the ICCM can accurately predict the natural frequency and mode shape of the annular plate. The numerical results show that the ICCM can be used effectively for the free vibration problem of plate with a hole compared to the Rayleigh-Ritz method and the finite element method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.06a
• /
• pp.1939-1944
• /
• 2000

Different test methods were used to measure and compare the loss factor of a steel beam. They are free vibration logarithmic decay method, half-power bandwidth method using narrow-band analysis, wide-band analysis method with inverse FFT. In these tests, specimens are clamped at one end. Free vibration method and half-power bandwidth method gave good results. Effect of vibration pick-ups were tested. We also tried center excitation method but could not obtain loss factor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2013.04a
• /
• pp.780-787
• /
• 2013

Virtual Seat Method (VSM) is used in this study for a combined evaluation method (objective & subjective) to determine comfort value of passenger vehicle seat in terms of idle vibration. In the study, a process for applying VSM divided into two stages is established. Two kinds of seat mounting passenger vehicle and six subjects are employed to compare the comfort value obtained by VSM method and by SEAT value. As a conclusion, the results by the two methods were well consistent so that VSM is verified as a method to measure ride comfort of seat in terms of idle vibration at passenger vehicle.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.26 no.2
• /
• pp.172-178
• /
• 2016

The location template matching (LTM) method is a technique of identifying an impact location on a structure, and is often applied to structural health monitoring and large scale human-computer interface (HCI) systems. The LTM method utilizes a certain measure of similarity between two time signals. The correlation coefficient is most widely used for this purpose, and the group delay based method is recently proposed to improve the accuracy of finding the best matching pair of signals. In practice, one of key essential consideration for implementing the LTM method is to guarantee that a sufficient number of vibration modes must be contained in the measured signal, and yet the lower sampling rate is needed for a real-time implementation. In this paper, the properties of correlation coefficient and group delay with respect to the number of vibration modes are investigated. A few important results are obtained through extensive computer simulations and experiments. If the number of vibration modes contained in the measured signal is more than four it is sufficient for the correlation based LTM method, while the group delay based LTM method requires smaller number of vibration modes.

• Structural Engineering and Mechanics
• /
• v.30 no.5
• /
• pp.603-617
• /
• 2008

Three dimensional coupled bending-torsion dynamic vibrations of thin-walled open section beam subjected to moving vehicle are investigated by transfer matrix method. Through adopting the idea of Newmark-${\beta}$ method, the partial differential equations of structural vibration can be transformed to the differential equations. Then, those differential equations are solved by transfer matrix method. An iterative scheme is proposed to deal with the coupled bending-torsion terms in the governing vibration equations. The accuracy of the presented method is verified through two numerical examples. Finally, with different eccentricities of vehicle, the torsional vibration of thin-walled open section beam and vertical and rolling vibration of truck body are investigated. It can be concluded from the numerical results that the torsional vibration of beam and rolling vibration of vehicle increase with the eccentricity of vehicle. Moreover, it can be observed that the torsional vibration of thin-walled open section beam may have a significant nonlinear influence on vertical vibration of truck body.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2005.04a
• /
• pp.375-382
• /
• 2005

In this paper, a practical control method of wind-induced vibration of high-rise buildings is presented in the form of resizing algorithm. In the structural design process for high-rise buildings, the lateral load resisting system for the building is more often determined by serviceability design criteria including wind-induced vibration level. Even though many drift method have been developed in various forms, no practical design method for wind induced vibration has been developed so far. Structural engineers rely upon heuristic or experience in designing wind induced vibration. The performance of the proposed method is evaluated by comparing wind-induced vibration levels estimated both from approximate techniques and wind tunnel test.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.1 no.4
• /
• pp.37-43
• /
• 1997

Damages and public complaints are increased due to construction noise and vibration from several sources. It is urgently needed to develop the easy and practical method to estimate the vibration effect. In this study, to predict the vibration effect, the method using the response spectrum with amplification factor concepts prroposed by Newmark and Hall is used. Also the applicability of the method is examined. Vibration measurement on subway structure, foundation and building structures are performed and the results show that the provided method is practical and can be used to predict the vibration effect.