• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.136-141
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• 1996

A new suspension model of an optical pick-up actuator is developed. This model is very stable and easily manufactured owing to its specially designed geometry. In designing the suspension, the first two natural frequencies are kept lying in a certain range and sub-resonance frequencies are made as high as possible. The vibration and sensitivity analysis needed for optimal design is based on a simplified beam model of the bobbin-suspension structure. The investigation of the strain energy distribution in each vibration mode appears to be very useful.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.334-339
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• 1998

The free vibration analysis of the simply supported steel and composite cylindrical shells are investigated. The natural frequencies and mode shapes of the shell are experimentally obtained by impact testing using an impact hammer and an accelerometer. The effects of the material and geometry on the vibrational characteristics of the shell are examined. The experimental results are compared with the analytical and a finite element results. They showed good agreement with each other.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.402.1-402
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• 2002

A linearly tapered beam immersed partially in other material is considered and is modelled as a linearly tapered Bernoulli-Euler beam fixed at the bottom with a concentrated mass at the top. Its governing equations is derived and its free vibration analysis is performed for various boundary conditions. And the rotatory inertia of the eccentric lumped tip mass is considered. (omitted)

• Journal of KSNVE
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• v.10 no.1
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• pp.138-143
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• 2000

Longitudinal vibration of an axially moving material is investigated by using the assumed modes method. To circumvent a difficulty in choosing the comparison functions which satisfy the boundary conditions, the assumed modes method is adopted by which equations of motion are discretized. Based on the discretized equations, the complex eigenvalue problem is solved and then the effects of the translating velocity on the natural frequencies and modes are analyzed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.92-95
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• 2005

In this study, Heavy-weight floor impact sound and vibration in concrete structures with different slab thickness have been measured in a test building. It was found that natural frequency increased according to increases of slab thickness, and acceleration level decreases. Results also show that the measurements in the 210 and 240mm slab structures are complied with the result from finite element analysis but the In and 180mm slab structures are not because the structures are constrained to the ground. Therefore, in modelling process the condition of sub-structures should be examined in relation to the boundary conditions.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.3
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• pp.230-235
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• 2004

This paper deals with the free vibration analysis of circular strip foundations with the variable breadth. Taking into account effects of both rotatory inertia and shear deformation, differential equations governing free vibrations of such foundations are derived. The Winkler foundation is chosen as the model of soil foundation. The breadth of strip foundation is assumed to be a linear function. The differential equations are solved numerically to calculate natural frequencies. In numerical examples, the strip foundations with the hinged-hinged, hinged-clamped. clamped-hinged and clamped-clamped end constraints are considered. The parametric studies are conducted and the lowest four frequency parameters are reported in figures as the non-dimensional forms.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.27 no.1
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• pp.107-113
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• 2017

The dynamic characteristics including natural frequencies and excitation frequencies are evaluated for a small 10 kW vertical axis wind turbine. Acceleration responses were measured at 12 distributed locations for impact vibration tests, ambient vibration tests during non-operational and operational conditions, and braking tests during operational condition. The natural frequencies for the lowest 2 bending modes and the first torsional mode were estimated and also the excitation frequencies, i.e. 1P, 2P, 4P, were also estimated according to the rotational speed using the responses under operational conditions (i.e. power generation condition).

• Structural Engineering and Mechanics
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• v.21 no.2
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• pp.169-184
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• 2005

This study deals with the free vibration of a circular plate in contact with a fluid; submerged in fluid, beneath fluid or on fluid. An analytical method based on the finite Fourier-Bessel series expansion and Rayleigh-Ritz method is suggested. The proposed method is verified by the finite element analysis using commercial program with a good accuracy. The normalized natural frequencies are obtained in order to estimate the relative added mass effect of fluid on each vibration mode of the plate. Also, the location of plate coupled with fluid and the cases of free and bounded fluid surface are studied for the effect on the vibration characteristics.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.495-500
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• 2001

Because of resonance between natural frequency of the second floor base for IPB(Isolated Phase Bus) duct supports in a power plant and operation frequency of the turbine, there was high amplitude vibration on IPB duct. To reduce vibration of IPB duct, Firstly it was set a FEM model to seek the mode shape for the concrete structure. Secondly, it was carried out dynamic analysis for the FEM model. Lastly, because the natural frequency of the concrete structure could not be changed, it was changed supports position for the IPB duct near to beams. It resulted in reducing vibration of IPB duct.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.8
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• pp.951-958
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• 2011

In this paper, the purpose is to investigate the vibration characteristics and the design of resonance avoidance of the unmanned helicopter master. Based on the Euler-Bernoulli beam theory for helicopter master, the equation of motion is derived by using extended Hamilton's principle. It was studied about the natural frequency of helicopter master as the design variances(tip mass, length and diameter of master). Also, it was compared the theoretical results for natural frequency with the results of FE analysis. The results of this study showed the vibration characteristics of helicopter master for the design of resonance avoidance.