• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.3
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• pp.185-192
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• 2004

Vibration table is required to obtain high packing density in expendable pattern casting process. Packing density. which is an important manufacture factor, depends on the vibration pattern induced by vibration table. In general, circular vibration pattern is recognized as the best pattern. The existing vibration table is investigated to identify current vibration pattern and consider a countermeasure. Modal test is utilized to identify the dynamic characteristics of vibration table, and finite element method is used to propose the improved design. In simulation using finite element method, the position of stiffeners is obtained to satisfy the required dynamic characteristics.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.379-382
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• 2007

The proper orthogonal decomposition(POD) is used to the modal analysis of microcantilever of dynamic mode atomic force microscopy(AFM). The proper orthogonal modes(POM) are extracted from vibrating signals of microcantilever when it resonates and taps the sample. The POMs resemble the linear normal modes(LNM) of cantilever vibrating at each resonance frequency. Some of POMs in tapping microcantilever show quite different shapes from the POMs of the resonating microcantilever. Also this POMs can be applied to model for the complex nonlinear behavior of the dynamic mode AFM microcantilevers.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.216-223
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• 1999

This study was intended to determine the inertia , damping and stiffness properties of the cab-suspension of agricultural tractors by applying the direct system identification method (DSIM). Since the rigid and elastic modes of the cab-suspension are not likely to be separated clearly, direct application of the DSIM may result in large computation error. To solve such a problem, a method of locating mass center of the cab were determined by assuming the behavior of the cab-suspension is a rigid body motion. The dynamic parameters of the cab-suspension were then determined by applying the DSIM with the known coordinates of the mass center. The constraints of spatial matrices of the cab-suspension also make the algorithm for the DSIM perform better. The values of dynamic parameters determined by this method agreed well with those determined by the experiment.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.10a
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• pp.103-110
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• 1999

Dynamic responses of steel composite bridges for the Korean high-speed railway are analyzed by a modal analysis. The bridge is modeled as a simply supported beam structure and a vehicle of TGV-K is modeled using a moving load assumption. When the train is moving on a bridge, its deck shows resonance phenomenon at a critical velocity. However, it is observed that the dynamic response is greatly reduced at a special range of the span length. The results show that the reduction effect should be considered ill designing the railway bridges. A parametric study of tile dynamic response is performed for different span lengths, and specific train speeds train should be considered in designing the high speed railway bridge are suggested.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.12
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• pp.2268-2278
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• 1992

The vibratory modal for the face milling operation is assumed as a multi degrees of freedom system. The parameters of the system are determined based on the cutting experiment. From the relative displacements of this system the dynamic cutting forces were derived and simulated by the double modulation principle. The simulated cutting forces and measured cutting forces have a good agreement in time and frequency domains.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.689-694
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• 2003

An iterative modal analysis approach is developed to determine the effect of transverse open cracks on the dynamic behavior of simply supported pipe conveying fluid subject to the moving mass. The equation of motion is derived by using Lagrange's equation. The influences of the velocity of moving mass and the velocity of fluid flow and a crack have been studied on the dynamic behavior of a simply supported pipe system by numerical method. The presence of crack results in higher deflections of pipe. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments i.e. the crack is modelled as a rotational spring. Totally, as the velocity of fluid flow and the crack severity are increased, the mid-span deflection of simply supported pipe conveying fluid is increased. The time which produce the maximum dynamic deflection of the simply supported pipe is delayed according to the increment of the crack severity.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.2
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• pp.28-33
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• 2003

This study is performed to evaluate and design the dynamic characteristics of the onboard machinery with resilient mounts. To avoid resonance with onboard machinery and external force, it is necessary to calculate natural frequencies of the resilient mounting system more accurately. Natural frequencies of on board machinery are determined by rigid body properties(mass, moment of inertia, center of mass) of machinery and stiffness of mounts. But it is very difficult to calculate rigid body properties theoretically. And stiffness properties of rubber mounts vary with dynamic displacement, pre load, frequency and temperature, and so on. In this study, we have identified rigid body properties using experimental modal analysis and estimated dynamic stiffness of rubber mount for onboard machinery using measured vibration response during seatrial. We measured displacement excitation through deck under mounts and evaluated relationship between modes of resilient mounting system and main excitation sources of a ship.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.11
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• pp.970-977
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• 2008

This paper deals with the dynamic characteristics of the shaft with impeller model which is the most important part in developing the resin mixing machine. Through reverse engineering, it is possible to make the shaft with impeller geometry model which is necessary vibration characteristic analysis by commercial impeller. The natural frequency analysis and structural analysis using finite element analysis software are performed on the imported commercial shaft with impeller model. The most important fundamental natural frequency of the shaft with impeller model is around 14.5 Hz, which well agrees with modal testing. The most effective design variables were extracted by ANOM(analysis of means) and pareto chart. This paper presents approximation 2nd order polynomial as design variables using RSM(response surface methodology). Generally, RSM take 2 or 3 design variables, but this method uses 5 design variables with table of mixed orthogonal array. Further more, the analyzed result of the commercial shaft with impeller is to be utilized for the structural design of resin chock mixing machine.

• Journal of Mechanical Science and Technology
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• v.16 no.6
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• pp.819-828
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• 2002

An analytical method is presented for evaluation of the steady state periodic behavior of nonlinear systems. This method is based on the substructure synthesis formulation and a MS (multiple scales) procedure, which is applied to the analysis of nonlinear responses. The proposed procedure reduces the size of large degrees-of-freedom problem in solving nonlinear equations. Feasibility and advantages of the proposed method are illustrated with the nonlinear rotating machine system as an example of large mechanical structure systems. In addition, its efficiency for nonlinear response prediction will be shown by comparison of other conventional methods.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.04a
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• pp.89-94
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• 2000

Because the structural elements used in the automobile, astronautic and ship industries are put in dynamic loading environments, much interest is given to the damping of the structural elements, as well as high flexural rigidity and strength per density. Therefore, in this study, the structural damping value of the aluminum honeycomb sandwich plate(AHCP) has been experimentally extracted, and directly applied to the finite element, for the dynamic analysis of the plate considering the structural damping. The analysis results of this theory was compared with the results of the actual modal analysis method. It was observable that the two analyses concurred, establishing the structural damping and analysis method of the AHSP.