• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.325.1-325
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• 2002

This paper presents property of the squeeze mode type mount using Magneto-Rheological fluid (MR fluid). The mount can isolate multi-directional vibrations, and also effectively reduce the vibrations in a wide range of disturbance frequency by controling the applied magnetic field. The shape of the mount is the same that of squeeze film damper. In the present work, the performance of this mount was experimentally investigated according to changing the magnetic field strength. (omitted)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.566-568
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• 2008

An E-OPMT(Electronically-controllable OPMT) was developed as an alternative of OPMT which could adjust the direction of the generated guided waves in a plate manually. The key idea of controlling the wave direction electronically is based on a few sets of axisymmetric figure-of-eight coils and the magnet which is located for making static omni-directionally biasing magnetic field over the patch. However, in order to explain wave phenomenon generated by this transducer, a new approach is required because there are various combinations between static biasing magnetic field and dynamic actuating magnetic field on the patch, not similar to OPMT. In this paper, the experiments were performed to understand characteristics of E-OPMT and the new theoretical analysis was set up for explaining the result.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.229-234
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• 2001

A practical and effective semi-active on-off control law is developed for vibration attenuation of a natural, multi-degree-of-freedom suspension system, when its operational response mode is available. It does not need the accurate system parameters and dynamics of semi-active actuator. It reduces the total vibratory energy of the system including the work done by external disturbances and the maximum energy dissipation direction of the semi-active control device is tuned to the operational response mode of the structure. The effectiveness of the control law is illustrated with a three degree-of-freedom excavator cabin model.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.888-893
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• 2004

This paper proposed a dual actuator using bimorph PZT for information storage device based on prove array NSOM(Near-field Scanning Optical Microscopy). The gap between the media and the optical head should be maintained within the optical tolerance. Therefore, a new actuator having high sensitivity is required. Bimorph PZT, which has fast access time and high sensitivity characteristic, is suitable for this precise actuating system. This paper is focused on derivation of mathematical model of dual bimorph PZT actuator and control algorithm. Hamilton's principle was used for mathematical model. The model is verified by FEA(Finite Element Analysis), and compared with experimental results. Different control algorithms were used f3r two bimorph PZT actuating same direction and opposite direction. The gap between recording media and optical head was controlled within 20nm in experiment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.301-308
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• 2000

The power flow analysis(PFA) has been performed to analyze the vibration of coupled plates excited by a point force in an arbitrry direction. The energy governing equations for longitudinal, shear and flexural waves were solved to predict the vibrational energy density and intensity. The wave transmission approach was used to consider the mode conversion at the joints of the coupled plates. Numerical results for energy density and intensity on the coupled plates were presented. Comparison of the results by PFA with exact results showed that PFA can be an effective tool to predict the spatial variation of the vibrational energy and intensity on the coupled plates at high frequencies.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.686-690
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• 2012

The modal test has been carried out using the exciter machine to investigate the vibration characteristics of the hull and super structure of the ship. The conventional exciter acts only one(1) direction and the exciter should be reinstalled for different direction test, which consumes additional expense. The 3 axes exciter has been designed of which force acts three directions without reinstallation for efficient modal test of the ship. It consists of rotatable base frame structure and the clutch mechanism for the unbalances to excite three directions. And the 3 axes exciter for the local structure has been made in advance and its performance test was carried out in the laboratory. The developed 3 axes exciter shows the ability of three-directions excitation with simple operation and modal test for the various local structure of the ship will be performed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.2 s.95
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• pp.225-231
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• 2005

This paper presents a design method for the structural-acoustic coupled radiator that can emit sound in the desired direction. A coupled system that has a finite space and a semi-infinite space separated by two flexible walls and an opening is considered. An objective function is selected to maximize radiation power on a main axis and minimize a side lobe level. To get initial values, prediction of a pressure distribution on field points and radiation pattern of the structural-acoustic coupling system is shown at a coupled-resonant frequency. Three different optimization methods are adapted to design the coupled radiator. Pressure and intensity distribution of the designed radiator is presented.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.91-96
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• 2013

In this paper, vibration response of gravity-type caisson breakwater is analyzed to suggest the direction for structural health monitoring (SHM) on harbor caisson structure. To achieve the objective, the following approaches are implemented. Firstly, vibration analysis methods are selected to examine the dynamic characteristics of the lab-scale caisson in the frequency and the modal domain. Secondly, vibration tests on the lab-scale caisson breakwater which is installed in 2-D wave tank were performed under several water level conditions. Thirdly, vibration response of the lab-scale caisson were analyzed in the frequency and modal domain. Finally, the direction of SHM for gravity-type caisson breakwater was suggested.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.234-238
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• 2003

Ultra small optical drive or PCMCIA type needs a focusing actuator because or applying Blue Laser and enhancing compatibility according to disk physical specification. Based on this need, this paper presents a novel focusing actuator adapted for ultra small optical drive of PCMCIA type. The focusing actuator using Lorenz force generated consists of coil, magnets and plate springs of pivoting. The design issues of the focusing actuator are the flexibility to focus direction, the rigidity to track direction and the higher natural mode of the moving part. For settling these Issues, this paper present mechanical design, computer simulations and test results of the realized focusing actuator. Finally, suitability and usefulness of the focusing actuator was demonstrated by the comparison of simulations and test results in a view of the possibility adapted for ultra small optical drive.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1061-1064
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• 2006

Optimal design of functionally graded plates is investigated considering stress and critical temperature. Material properties are assumed to be temperature dependent and varied continuously in the thickness direction. The effective material properties are obtained by applying linear rule of mixtures. The 3-D finite element model is adopted using an 18-node solid element to analyze more accurately the variation of material properties and temperature field in the thickness direction. For stress analysis, the tensile stress ratio and compressive stress ratio of the structure under mechanical load are investigated. In the thermo-mechanical buckling analysis, temperature at each node is obtained by solving the steady-state heat transfer problem and Newton-Raphson method is used for material nonlinear analysis. Finally, the optimal design of FGM plates is studied for stress reduction and improving thermo-mechanical buckling behavior, simultaneously.