• International Journal of Aeronautical and Space Sciences
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• 제15권3호
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• pp.302-308
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• 2014

In this paper, a detailed investigation of the random vibration test is presented for strapdown inertial navigation systems (INS). The effect of the random vibration test has been studied from the point of view of navigation performance. The role of distribution functions and RMS value is represented to determine a feasible method to reject or reduce vibration related error in position and velocity estimation in inertial navigation. According to a survey conducted by the authors, this is the first time that the effect of the distribution function in vibration related error has been investigated in random vibration testing of INS. Recorded data of navigation grade INS is used in offline static navigation to examine the effect of different characteristics of random vibration tests on navigation error.

• International Journal of Advanced Culture Technology
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• 제5권3호
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• pp.67-72
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• 2017

Transform variation technique is constituted the vibration status of the flash-gap recognition level (FGRL) on the distribution recognition function. The recognition level condition by the distribution recognition function system is associated with the scattering vibration system. As to search a position of the dot model, we are consisted of the distribution value with character point by the output signal. The concept of recognition level is composed the reference of flash-gap level for variation signal by the distribution vibration function. For displaying a variation of the FGRL of the maximum-average in terms of the vibration function, and distribution position vibration that was the a distribution value of the far variation of the $Dis-rf-FA-{\alpha}_{MAX-AVG}$ with $5.74{\pm}1.12$ units, that was the a distribution value of the convenient variation of the $Dis-rf-CO-{\alpha}_{MAX-AVG}$ with $1.64{\pm}0.16$ units, that was the a distribution value of the flank variation of the $Dis-rf-FL-{\alpha}_{MAX-AVG}$ with $0.74{\pm}0.24$ units, that was the a distribution value of the vicinage variation of the $Dis-rf-VI-{\alpha}_{MAX-AVG}$ with $0.12{\pm}0.01$ units. The scattering vibration will be to evaluate at the ability of the vibration function with character point by the distribution recognition level on the FGRL that is showed the flash-gap function by the recognition level system. Scattering recognition system will be possible to control of a function by the special signal and to use a distribution data of scattering vibration level.

• The Korean Journal of Ecology
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• 제21권5_2호
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• pp.491-499
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• 1998

An investigation was performed to establish the mathematical theories of a vibration for the plant growth and a wave distribution of a plant population on the boundary condition of a limiting factor in the environment. The mathematical theories of the plant growth vibration and wave distribution had been elucidated by the plant growth and the timber line on the middle slope of the west side of Mt. Paektu. The Betula ermaruii composes the timber line on about 2,060 m elevation of sea label, has a growth vibration on the ground surface and takes a wave distribution due to a boundary condition of alpine temperature gradient.

• International Journal of Automotive Technology
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• 제5권3호
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• pp.189-194
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• 2004

The viscoelastic layer material is widely used to control the noise and vibration characteristics of the panel structure. This paper describes the design technology of the effective vibration damping treatment using the concept of the equivalent parameter of viscoelastic layer materials. Applying the equivalent parameter concepts based on theories of shell, it is possible to simulate the finite element analysis of damping layer panel treatments on the vibration characteristics of the structure. And it is achieved the reduced computational cost and the optimal design of topological distribution for the reduction of vibration effect.

• Coupled systems mechanics
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• 제10권1호
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• pp.61-77
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• 2021

The porosity of functionally graded materials (FGM) can affect the static and dynamic behavior of plates, which is important to take this aspect into account when analyzing such structures. The present work aims to study the effect of the distribution shape of porosity on the free vibration response of simply supported FG plate reposed on the Winkler-Pasternak foundation. A refined theory of shear deformation is expanded to study the influence of the distribution shape of porosity on the free vibration behavior of FG plates. The findings showed that the distribution shape of porosity significantly influences the free vibration behavior of thick rectangular FG plates for small values of Winkler-Pasternak elastic foundation parameters.

• 소음진동
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• 제8권5호
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• pp.814-820
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• 1998

Vibration data from two blasting sites were analyzed to determine the sufficient sample number for blasting vibration estimation. Most important result is that much more than 30 sample data and succeeding measurement are necessary to estimate confident blasting vibration level and to determine limit scaled distance.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2008년도 춘계학술대회
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• pp.290-307
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• 2008

The aim of this study was to estimate adverse effect on compression strength of corrugated fiberboard containers due to vibration during distribution process. Distribution environment such as road conditions and compression strength of corrugated fiberboard containers for selected agricultural products were studied. We found that increasing humidity does not effect significantly on natural frequencies of boxes, but results in accelerative effect to decrease compression strength of boxes. Box structures and product types also effect on loss of compression strength greatly.

• Smart Structures and Systems
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• 제30권2호
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• pp.135-143
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• 2022

The object of this paper is to investigate the free vibration behavior under the effect of carbon nanotube distribution in functionally graded carbon nanotube-reinforced composite (FG-CNTRC) by using higher-order shear deformation theories. In this work, we present a novel distribution method for carbon nanotubes in the polymer matrix by using a new exponential power law distribution of carbon nanotube volume fraction. It is assumed that the SWCNTs are aligned along the beam axial direction and the distribution of the SWCNTs may vary through the thickness of the beam with different patterns of reinforcement. The rule of mixtures is used in order to obtain material properties of the CNTRC beams. Hamilton's principle is used in deriving the equations of motion. The validity of the free Vibration results is examined by comparing them with those of the known data in the literature. The results that obtained indicate that the carbon nanotube volume fraction distribution play a very important role on the free vibrations characteristics of the CNTRC beam.

• Structural Engineering and Mechanics
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• 제43권3호
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• pp.395-410
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• 2012

The visualizing energy flow and control in vibrating stiffened plates with a cutout are studied using finite element method. The vibration intensity, vibration energy and strain energy distribution of stiffened plates with cutout at different excitation frequencies are calculated respectively and visualized for the various cases. The cases of different size and boundaries conditions of cutouts are also investigated. It is found that the cutout or opening completely changes the paths and distributions of the energy flow in stiffened plate. The magnitude of energy flow is significantly larger at the edges near the cutout boundary. The position of maximum strain energy distribution is not corresponding to the position of maximum vibrational energy. Furthermore, the energy-based control using constrained damping layer (CDL) for vibration suppression is also analyzed. According to the energy distribution maps, the CDL patches are applied to the locations that have higher energy distribution at the targeted mode of vibration. The energy-based CDL treatments have produced significant attenuation of the vibration energy and strain energy. The present energy visualization technique and energy-based CDL treatments can be extended to the vibration control of vehicles structures.

• Structural Engineering and Mechanics
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• 제82권2호
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• pp.151-161
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• 2022

In this study, the effect of porosity distribution pattern on the free vibration analysis of porous FG plates with various boundary conditions is studied. The material properties of the plate and the porosities within the plate are considered to vary continuously through the thickness direction according to the volume fraction of constituents defined by the modified rule of the mixture, this includes porosity volume fraction with four different types of porosity distribution over the cross-section. The governing partial differential equation of motion for the free vibration analysis is obtained using hyperbolic shear deformation theory. An analytical solution is presented for the governing PDEs for various boundary conditions. Results of the presented solution are compared and validated by the available results in the literature. Moreover, the effects of material and porosity distribution and geometrical parameters on vibrational properties are investigated.