• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.389-394
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• 2011

Existing FPS(Friction Pendulum System) is isolation system which is possible to isolate structures by pendulum characteristic from ground vibration. Structural natural frequency could be decided by designing the radius of curvature of FPS. Thus, response vibration could be reduced by changing natural frequency of structures from FPS. But effective periods of recorded seismic wave were various and estimation of earthquake characteristic could be difficult. If effective periods of seismic wave correspond to natural frequency of structures with FPS, resonance can be occurred. Therefore, CFPBS(Cone-type Friction Pendulum Bearing System) was developed for controlling the response acceleration and displacement by the slope of friction surfaces. Structural natural frequency with CFPBS can be changed according to position of ball on the friction surface which was designed cone-type. Therefore, Divergence of response could be controlled by CFPBS which had constantly changing natural frequency with low modal participation factor in wide-range. In this study, Seismic performance of CFPBS was evaluated by numerical analysis and shaking table test.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.2
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• pp.119-126
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• 2009

LCVA has an advantage that its natural frequency can be easily controlled by changing the area ratio of the vertical column and horizontal part. The previous studies investigated the dynamic characteristics of the LCVA under harmonic load. This study experimentally obtained the first and second mode natural frequencies of the LCVA from shaking table tests using white noise and compared the values with the ones by previous study. Test results show that the measured first mode natural frequency of the LCVA has a different value compared with calculated one. The effective length($L_e$) was revised using by power equation. In the case01 to 19, the standard deviation($S_r$) is 4.7292 and the coefficient of correlation(r) is 0.9856. In the case21 to 61, the standard deviation($S_r$) is 14.2143 and the coefficient of correlation(r) is 0.9935. The second mode frequency increases with the increasing area ratio, which is due to the sloshing motion effect resulting from the large area of the vertical column.

• Coupled systems mechanics
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• v.12 no.2
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• pp.127-149
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• 2023

A theoretical method is developed to analyze the free vibration of an elastic annular plate in contact with an ideal liquid. The displacement potential functions of the contained liquid are expressed as a combination of the Bessel functions that satisfy the Laplace equation and the liquid boundary conditions. The compatibility condition along the interface between the annular plate and the contained liquid is taken into account to consider the fluid-structure coupling. The dynamic displacement of the wet annular plate is assumed to be a combination of dry eigenfunctions, allowing for prediction of the natural frequencies using the Rayleigh-Ritz method. The study investigates the effect of radial liquid boundary conditions on the natural frequencies of the wet annular plate, considering four types of liquid bounding: outer container bounded, outer and inner bounded, inner bounded, and radially unbounded. The proposed theoretical method is validated by comparing the predicted wet natural frequencies with those obtained from finite element analysis, showing excellent accuracy. The results indicate that the radial liquid bounding effect on the natural frequencies is negligible for the axisymmetric vibrational mode, but relatively significant for the mode with one nodal diameter (n =1) and no nodal circle (m' = 0). Furthermore, the study reveals that the wet natural frequencies are the largest for the plate with an inner bounded cylinder among the radial liquid boundary cases, regardless of the vibration mode.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.543-548
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• 2006

This paper presents the vibration characteristics of scaffolding structures with a hoist according to payloads. In order to analyze the vibrational and structural characteristics for 20-step scaffolding structure, structural and vibrational characteristics for 2-step scaffolding structure were compared with some experimental results. The numerical results for natural frequencies of scaffolding structures have a good agreement with experimental ones. Through the numerical analysis, firstly, it is shown that the maximum stress of scaffolding structures is lower than von-mises yield criteria when four persons with total weight of 280kgf are working at the top of the scaffolding structures. Secondly vibration characteristics including natural frequencies and modes for scaffolding structures are shown in case of various kinds of moving masses.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.2
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• pp.130-135
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• 2015

Recently, as a result of the application of large and multi-blade propellers with high efficiency for large vessels, the vertical bending stiffness of propulsion shafting system tends to be declined. For some specific vessels, the shaft arrangement leads to the forward stern tube bearing to be omitted, decreasing vertical bending stiffness. In this respect, decreased vertical bending stiffness causes the problem which is the blade order resonance frequency to be placed within the operational rpm range of propulsion shafting system. To verify whirling vibration, the measurement should be carried out covering from operating rpm up to target rpm, however, the range is un-measurable generally. In order to resolve the measurement issue, this study shows the measuring method and the assessment method of relevant natural frequency of whiling vibration by using measured harmonic order component of whirling vibration.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.4
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• pp.317-323
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• 2014

This study is concerned with the free vibration analysis of an inextensible uniform rope with a spring-mass system at the tip. The rope is hanged vertically in a gravitational field. This problem is related to the free vibration of an elevator rope connected to an elevator cage. The equation of motion and the corresponding boundary conditions are derived by using the Hamilton's principle. The general solution of the governing equation of motion is expressed in terms of Bessel functions. The characteristic equation was derived by applying the boundary conditions. The characteristic values which are in fact non-dimensionalized natural frequencies were obtained numerically. The effects of mass and spring constant were investigated. The numerical results show how the tip mass and spring affect the natural frequencies of the rope.

• Journal of the Korean Society for Railway
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• v.6 no.4
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• pp.286-293
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• 2003

The prototype of Korean high speed train (HSR350), composed of two power cars, two motorized cars and three trailer cars, has been designed, fabricated and tested. In this paper, the body vibration has been reviewed from the viewpoint of the vehicle's safety and the vibration limits for components and sub-assemblies mounted on the car-body using by the experimental method. And, the dynamic characteristics, such as jerk, natural mode and kinematic mode, have been reviewed. The KHST has been run to 300 km/h in the KTX line and the results of on-line test show that it has no problems in the vehicle's safety and the vibration limits. And the characteristics of body vibrations has been predicted at 350 km/h by fitting curve about the measured acceleration signals.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.7 no.3
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• pp.151-159
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• 1978

A heat transfer model for the case of simultaneous vibration of both the heated surface and its surrounding medium is constructed and the dimensional analysis is applied to this model in order to and the governing dimensionless Parameters in which the vibration effects the heat transfer. In the second Part of this study, an experimental investigation of the effect of vibration on natural convective heal transfer from spheres has been performed for the case of the external oscillatory motion being imposed on the heated surface which is immersed in an otherwise undisturbed air, The ranges of the experimental variables were: temperature difference 10 to $120^{\circ}C$; vibration frequency 10 to 120Hz; displacement amplitude 1.3 to 12.5mm. Three different diameter aluminum were used as the experimental models. Improvements in heat transfer due to vibration were observed, with the maximum increase being 330 Percent. A dimensionless correlation describing the measured heat transfer data is given.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.378-379
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1337-1338
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• 2013