• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.3
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• pp.80-85
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• 2012

The ultrasonic cutting method is which cutting by applying high frequency vibrational energy into specific area at constant pressure. Ultrasonic cutting is consisted of power supply, transducer, booster and cutting tool. Precise designing is required since each part's shape, length and mass can affect driving frequency and vibration mode. This paper focused to cutting tool design, its length L was set by calculating vibration equation. And the value of the shape parameter a was diversified as the integral multiple and the result of 40,189Hz the analysis of Modal was shown in the length 30mm of the result of performance b in the 11th mode Also by performing harmonic response analysis, the frequency response result was 40,189Hz, which was similar to modal analysis result.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.325-333
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• 2000

To predict vibrational energy density and intensity of partitioned complex system structures in medium-to-high frequency ranges, Power Flow Finite Element Method(PFFEM) programs for the plate elements are developed. The flexural, longitudinal and shear waves in plates are formulated and the joint element equations for multi-couped plates are fully developed. Also the wave transmission approach has been introduced to cover the energy transmission and reflection at the joint plate elements. Using the developed PFFEM program the energy density and intensity of the submarine and automobile shape structures are predicted with a harmonic point force at a single frequency.

• Advances in nano research
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• v.8 no.4
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• pp.283-292
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• 2020

In the present research, differential quadrature (DQ) method has been utilized for investigating free vibrations of porous functionally graded (FG) micro/nano beams in thermal environments. The exact location of neutral axis in FG material has been assumed where the material properties are described via porosity-dependent power-law functions. A scale factor related to couple stresses has been employed for describing size effect. The formulation of scale-dependent beam has been presented based upon a refined beam theory needless of shear correction factors. The governing equations and the associated boundary conditions have been established via Hamilton's rule and then they are solved implementing DQ method. Several graphs are provided which emphasis on the role of porosity dispersion type, porosity volume, temperature variation, scale factor and FG material index on free vibrational behavior of small scale beams.

• Coupled systems mechanics
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• v.9 no.3
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• pp.201-217
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• 2020

This paper employs differential quadrature method (DQM) and nonlocal strain gradient theory (NSGT) for studying free vibrational characteristics of porous functionally graded (FG) nanoplates coupled by visco-elastic foundation. A secant function based refined plate theory is used for mathematical modeling of the nano-size plate. Two scale factors are included in the formulation for describing size influences based on NSGT. The material properties for FG plate are porosity-dependent and defined employing a modified power-law form. Visco-elastic foundation is presented based on three factors including a viscous layer and two elastic layers.The governing equations achieved by Hamilton's principle are solved implementing DQM. The nanoplate vibration is shown to be affected by porosity, temperature rise,scale factors and viscous damping.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.152-157
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• 2005

Recently, higher speeds have been promoted in old overhead-lines. For high-speed operation in electric railways, increasing contact loss of the pantograph is one of the most important subjects. The contact loss causes power interruption and increases wear of contact strips and contact wires. In order to investigate the causes of contact loss and to work out effective improvement methods, theoretical analyses, experiments have been carried out. First of all, the wave propagating velocity (phase velocity) and characteristics of contact wire are one of the important indices for the current collecting performance. In this paper, mathematical formula arc derived for the prediction of the traveling wave velocity. The measured values in the experiment agree well with the theoretical predictions.

• Journal of the Korean Society of Safety
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• v.15 no.3
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• pp.45-51
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• 2000

This paper studies the effect of vibrational characteristics of the various tubes analyzed though experiment. By an experiment analysis we found out that the factor of system vibration is fluid-structure interaction of tube line. In fluid-filled tube system we study on the influence that the natural frequency of system and the frequency of wave motion produce upon through three experiments. Three experiments are modal test on each tube, FRF in continuous system, and vibrating tests when the system is driving on. From the results of the experimental studies, we obtained that the natural frequencies of system are very important than wave induced vibrations. and according to the variation of configuration, the frequencies are different each other. And we found that though fluid passed away through the tube, the tendency of system vibration level was similar with the mode shape at the simple system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1083-1088
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• 2001

To predict vibrational energy density and intensity of complex structures in medium-to-high frequency ranges, Power Flow Finite Element Method(PFFEM) programs for the plate, beam and some coupled structural elements are developed at present. The vibration energy density and intensity of foreign vehicle is predicted successfully with FE full model of 60,000 DOF using the developed PFFEM program.

• Steel and Composite Structures
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• v.32 no.2
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• pp.281-292
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• 2019

Nonlocal elasticity and Reddy plant theory are used to study the vibration response of functionally graded (FG) nanoplates resting on two parameters elastic medium called Pasternak foundation. Nonlocal higher order theory accounts for the effects of both scale and the effect of transverse shear deformation, which becomes significant where stocky and short nanoplates are concerned. It is assumed that the properties of FG nanoplate follow a power law through the thickness. In addition, Poisson's ratio is assumed to be constant in this model. Both Winkler-type and Pasternak-type foundation models are employed to simulate the interaction of nanoplate with surrounding elastic medium. Using Hamilton's principle, size-dependent governing differential equations of motion and corresponding boundary conditions are derived. A differential quadrature approach is being utilized to discretize the model and obtain numerical solutions for various boundary conditions. The model is validated by comparing the results with other published results.

• Advances in nano research
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• v.8 no.3
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• pp.191-202
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• 2020

The article brings the study of nonlocal, surface and the couple stress together to apparent the frequency retaliation of FG nanobeams (Functionally graded). For the examination of frequency retaliation, the article considers the accurate spot of neutral axis. This article aims to enhance the coherence of proposed model to accurately encapsulate the significant effects of the nonlocal stress field, size effects together with material length scale parameters. These considered parameters are assimilated through what are referred to as modified couple stress as well as nonlocal elasticity theories, which encompasses the stiffness-hardening and softening influence on the nanobeams frequency characteristics. Power-law distribution is followed by the functional gradation of the material across the beam width in the considered structure of the article. Following the well-known Hamilton's principle, fundamental basic equations alongside their correlated boundary conditions are solved analytically. Validation of the study is also done with published result. Distinct parameters (such as surface energy, slenderness ratio, as nonlocal material length scale and power-law exponent) influence is depicted graphically following the boundary conditions on non-dimensional FG nanobeams frequency.

• Journal of Power System Engineering
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• v.16 no.1
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• pp.24-29
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• 2012

Recently, in the movie theater, the special chair is installed to maximize the viewing effect of movies. It is structured to convey a vibrational stimulus to a specially-designated parts of human body by attaching a vibration transducer to a existing theater chair. This paper describes the analysis of the vibration transfer characteristic of a foaming sponge seat for the design of the special chair. We could not apply the structural analysis S/W because it is difficult to obtain the mechanical properties and damping coefficients of the various type sponges. And then we computed the transfer functions by the global curve fitting program based on experimental modal analysis. The experimental response results comparatively coincide with those by the global curve fitting program. We also could obtain the natural frequencies, the modal damping coefficient ratio, the modal vectors and the whole transfer functions. Therefore we could analyze the dynamic characteristic for design of foaming sponge seat.