• Transactions of the Korean Society of Automotive Engineers
• /
• v.8 no.4
• /
• pp.177-185
• /
• 2000

The deformation characteristics is one of the major factors to resume the crash configuration in collision accident reconstruction. Crash analysis are carried out using finite element method and body stiffness equations representing force-deformation relationship are derived, Two different crash conditions : 1) frontal barrier impact 2) frontal impact between cars are given for the derivation of the equations. The stiffness coefficient of equation by method 2) is larger than that by method. 1). Crash analysis between two vehicles is accomplished with three crash angles and three velocities for each angle condition. The deformations are measured for six selected points and deformation energies are calculated using the derived equations. Equation by method 2) results in better estimation of deformation energy than that by method 1) for all crush configurations. The estimated energies can be utilized as one of indices to identify the type of the collision accident result.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.111.4-111
• /
• 2001

In this paper, an adaptively tuned dynamic absorber is proposed. The adaptively tuned dynamic absorber is a dynamic absorber whose stiffness is tuned so that the natural frequency of the absorber coincides with the operating or natural frequency estimated by an adaptive algorithm. The feature of this absorber is as follows. It has an electrodynamic device for the stiffness control. Using Lorenz´s force, it changes the stiffness by changing the applied current. The change of stiffness results in the natural frequency shift, because its mass and damping coefficient are fixed. We may reduce the vibration of the overall system by tuning the natural frequency of the dynamic absorber to the resonant frequency of the structure, when the dominant single tone oscilation occurs in the system ...

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2001.04a
• /
• pp.429-434
• /
• 2001

This paper has been presented the dynamic effect by the journal speed, eccentricity and source positions in order to overcome the defects of air bearing such as low stiffness and damping coefficient. Choosing two row sources position of air bearing is different from previous investigations in the side of pressure distribution of air film by the wedge effects. An experimental study was performed to compare theoretical analysis. The dynamic stiffness was measured in actual cutting. It helps predicting of air spindle s characteristic in machining of die more precisely. The results of investigated characteristics was applied to air spindle for high speed milling.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.11 no.9
• /
• pp.462-474
• /
• 2001

In this paper, Generalized Differential Quadrature Method is applied to the buckling analysis of built-up columns without or with stay plates. numerical analysis using GDQM is carried out for various boundary conditions(simply supported conditions, fixed conditions, fixed-simply supported conditions), dimensionless stiffness parameter and dimensionless inertia moment parameter. The accuracy and convergence of solutions are compared with exact solutions of Gjelsvik to validate the results of GDQM. Results obtained by this method are as follows. 91) This method can yield the accurate numerical solutions using few grid points. (2) The buckling load of built-up column increases as the dimensionless stiffness parameter decreases. (3) The effects of boundary conditions on the buckling load are not considerable as the dimensionless stiffness parameter increases. (4) The buckling load of built-up column increases due to the stay plate.

• Journal of KSNVE
• /
• v.2 no.1
• /
• pp.33-39
• /
• 1992

The problem of sound radiation from infinite elastic beams under the action of harmonic point forces is studied. The reaction due to fluid loading on the vibratory response of the beam is taken into account. The beam is assumed to occupy the plane z = 0 and to be axially infinite. The beam material and the elastic foundation re assumed to be lossless and Bernoulli-Euler beam theory including a tension force (T), damping coefficient (C) and stiffness of foundation $(\kappa_s)$ will be employed. The non-dimensional sound power is derived through integration of the surface intensity distribution over the entire beam. The expression for sound power is integrated numerically and the results are examined as a function of wavenumber ratio$(\gamma)$ and stiffness factor$(\Psi)$. Here, our purpose is to explain the response of sound power over a number of non-dimensional parameters describing tension, stiffness, damping and foundation stiffness.

• Journal of KSNVE
• /
• v.3 no.3
• /
• pp.245-251
• /
• 1993

The problem of sound radiation from infinite elastic beams under the action on harmonic moving line forces is studies. The reaction due to fluid loading on the vibratory response of the beam is taken into account. The beam is assumed to occupy the plane z=0 and to be axially infinite. The beam material and elastic foundation are assumed to be lossless and Bernoulli-Euler beam theory including a tension force (T), damping coefficient (C) and stiffness of foundation $(\kappa_s)$ will be employed. The non-dimensional sound power is derived through integration of the surface intensity distribution over the entire beam. The expression for sound power is integrated numerically and the results examined as a function of Mach number (M), wavenumber ratio$(\gamma{)}$ and stiffness factor $(\Psi{)}$. Here, our purpose is to explain the response of sound power over a number of non-dimensional parameters describing tension, stiffness, damping and foundation stiffness.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.786-791
• /
• 2004

This study proposed the analysis of mass position detection and modified stiffness due to the change of the mass and stiffness of structure by using the original and modified dynamic characteristics. The method is applied to examples of a cantilever and 3 degree of freedom by modifying the mass. The predicted detection of mass positions and magnitudes are in good agreement with these from the structural reanalysis using the modified mass.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.6 no.6
• /
• pp.80-87
• /
• 1998

In this study, the effects of residual shaft bow and flexible bearings of a single disk rotor are investigated. The stiffness coefficients of a shaft with initial deflection are different from those of a straight shaft. The stiffness coefficients are calculated using Castigliano theorem considering initial deflections. The stiffness coefficients, which are obtained in this study, are in good agreement with FEM results. The speed which causes zero amplitude is shown to be the square root of the ratio of residual bow amplitude to unbalance eccentricity in the case of rigid bearings and isotropic flexible bearings, but not in anisotropic bearings.

• Journal of Power System Engineering
• /
• v.21 no.5
• /
• pp.48-54
• /
• 2017

The transfer influence coefficient method which is an vibration analysis algorithm based on the transfer of influence coefficient is applied to the free vibration analysis of double cylindrical shells. After the computational programs for the free vibration analysis of double cylindrical shells were made using the transfer influence coefficient method and the transfer matrix method, we compared the results using the transfer influence coefficient method with those by the transfer matrix method. The transfer influence coefficient method provided the good computational results in the free vibration analysis of double cylindrical shells. In particular, The results of the transfer influence coefficient method are superior to those of the transfer matrix method when the stiffness of internal springs connecting a inside cylindrical shell and a outside cylindrical shell is very large.

• Proceedings of the KSR Conference
• /
• 1998.11a
• /
• pp.512-521
• /
• 1998

The roll characteristic of railway vehicle is an important factor that affects the roll-over of vehicle and lateral ride comfort of passenger. Generally the roll characteristics of railway vehicle is defined by the term of roll-coefficient, s, which represents the ratio of incline or carbody to that of rail-cant. The limit values of roll coefficient recommended in UIC Bre 0.4 for coach without pantograph and 0.15 for vehicle with pantograph. The roll coefficient can be calculated by VAMPIRE that is the well-known commercial software for analysis of dynamic behavior of railway vehicle. The value of roll coefficient is effected by height of gravity center of carbody, stiffness of primary and secondary suspension and etc. The calculated roll-coefficient for electric locomotive and passenger coach is 0.12 and 0.77 respectively, The additional equipment such as anti-roll bar is considered in order to decrease roll-coefficient of passenger coach. In relation to roll characteristics, the analysis for roll-over due to wind is a1so performed. The results show that roll-characteristics affect the roll-over of vehicle.