• Journal of Institute of Control, Robotics and Systems
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• v.16 no.6
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• pp.517-523
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• 2010

In this paper, we proposed an algorithm to detect aggressive driving status by analysing six kinds of driving patterns, which was achieved by comparing for the feature vectors using mahalanobis distance. The first step is to construct feature matrix of $6{\times}2$ size using frequency response of the time-series accelerometer data. Singular value decomposition makes it possible to find the dominant eigenvalue and its corresponding eigenvector. We use the eigenvector as the feature vector of the driving pattern. We conducted real experiments using three drivers to see the effects of recognition. Although there exists differences from individual drivers, we showed that driving patterns can be recognized with about 80% accuracy. Further research topics will include the development of aggressive driving warning system by improving the proposed technique and combining with post-processing of accelerometer signals.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.5
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• pp.75-84
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• 1996

planar circulator swith arbitrarily shaped ferrite resonators are analyzed in this paper. First, resonant frequencies and field distributions for the magnetized ferrite resonator are obtained using finite element method (FEM). Then the RF voltage distributions and other circuit parameters of the circulator which is formed by connecting three suitable transmission lines ot the ferrite resonator are derived from the green function . To remove the spurious solutions in analyzing the ferrite resonator, the results of eigenvalue analysis by node based FEM are comapred with the edge based fEM. The green function is expanded in terms of normalized eigenfunctions of th ecorresponding wave equation. Circulator parameters for circular disk resonator are clculated and compared with the analytical results. The experimental data for the designed circulator using hexagonal reosnator in the 850 MHz frequency range agree well iwth the simulated data.

• Journal of the Korean Institute of Telematics and Electronics
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• v.11 no.2
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• pp.12-21
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• 1974

Perturbation thorpe for quantum mechanics is extended to the derivation of a power equation for microwave propagation in a rectangular waveguiad filled with N-type silicon which is transversely magnetized. This approximation evolves in a unified manner from the eigenvalue formulation of maxwell's equation wherein the wave numbers are tthe eigenvalues of a linear operator. TE10 wave at 9.61GHz is employed for the experimental investigation of the microwave propagation through a transversely magnetized semiconductor. Results from first order perturbation agree well with the experiment where the bridge method using two Magic Tees is employed.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.491-496
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• 2003

In sensitivity analysis, semi-analytical method(SAM) reveals severe inaccuracy problem when relatively large rigid body motions are identified for individual elements. Recently such errors of SAM resulted by the finite difference scheme have been improved by the separation of rigid body mode. But the eigenvalue should be obtained first before the sensitivity analysis is performed and it takes much time in the case that large system is considered. In the present study, by constructing a reduced one from the original system, iterative method combined with mode decomposition technique is proposed to compute reliable semi-analytical design sensitivities. The sensitivity analysis is performed by the eigenvector acquired from the reduced system. The error of SAM caused by difference scheme is alleviated by Von Neumann series approximation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.7
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• pp.814-819
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• 2016

The Stockbridge damper is used to control the aeolian vibration of a overhead transmission line due to the natural wind under a low velocity, between 1 m/s to 7 m/s. The damper model can be simply derived with several design parameters and the location of eigenvalues of design parameters are important to determine the efficiency of energy dissipation by excitation itself with two counterweights. First, the importance of resonance frequencies of Stockbridge damper was reviewed through the analysis of frequency response function of damper system. Then, the best selection of design parameters was investigated with the introduction of objected function that minimize the distance between the calculated eigenvalues and target frequency points. The best choice of design parameters was reviewed using the simulated results from the objective function and the effectiveness of selected design case was discussed at the point view of practical implementation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.361.2-361
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• 2002

Substructures position is considered as design parameter to obtain optimal structural changes to raise its dynamic characteristics. In conventional SDM (structural dynamics modification) method, the layout of modifying substructures position is first fixed and at that condition the structural optimization is performed by using the substructures size and/or material property as design parameters. But in this paper as a design variable substructures global translational and rotational position is treated. (omitted)

• Steel and Composite Structures
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• v.20 no.5
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• pp.1087-1102
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• 2016

The paper proposes to characterize the free vibration behaviour of non-uniform cylindrical shells using spline approximation under first order shear deformation theory. The system of coupled differential equations in terms of displacement and rotational functions are obtained. These functions are approximated by cubic splines. A generalized eigenvalue problem is obtained and solved numerically for an eigenfrequency parameter and an associated eigenvector which are spline coefficients. Four and two layered cylindrical shells consisting of two different lamination materials and plies comprising of same as well as different materials under two different boundary conditions are analyzed. The effect of length parameter, circumferential node number, material properties, ply orientation, number of lay ups, and coefficients of thickness variations on the frequency parameter is investigated.

• Journal of Korean Society for Quality Management
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• v.23 no.3
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• pp.84-92
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• 1995

A method is proposed for the simultaneous optimization of several response functions that depend on the same set of controllable variables and are adequately represented by a response surface model (polynomial regression model) with the same degree and with constraint that the individual responses have the target values. First, the multiple responses data are checked for linear dependencies among the responses by eigenvalue analysis. Thus a set of responses with no linear functional relationships is used in developing a function that measures the distance estimated responses from the target values. We choose the optimal condition that minimizes this measure. Also, under the different degree of importance two step procedures are proposed.

• Journal of KSNVE
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• v.9 no.1
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• pp.103-112
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• 1999

A new modeling and analysis technique for one-dimensional distributed parameter systems is presented. First. discretized equations of motion in Laplace domain are derived by applying discretization methods for partial differential equations of a one-dimensional structure with respect to spatial coordinate. Secondly. the z and inverse z transformations are applied to the discretized equations of motion for obtaining a dynamic matrix for a uniform element. Four different discretization methods are tested with an example. Finally, taking infinite on the number of step for a uniform element leads to an exact dynamic matrix for the uniform element. A generalized modal analysis procedure for eigenvalue analysis and modal expansion is also presented. The resulting element dynamic matrix is tested with a numerical example. Another application example is provided to demonstrate the applicability of the proposed method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.492-498
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• 2000

As the disk rotation speed increases in information storage devices, aerodynamically excited disk vibration is induced by airflow around the disk. This paper investigates theoretical and experimental studies on the disk flutter instability in CD-ROM drives. The effect of airflow on the disk vibration is modeled as the distributed damping and lift forces. By analyzing the eigenvalue problem of the aero-elastic coupling model, we introduces a novel technique to predict the flutter speed by comparing experimental natural frequencies with analytical ones of a disk rotating in vacuum. The new method predicts that the vibration mode with two nodal diameters in a CD disk experiences the first flutter instability at 12,000 rpm.