• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.971-976
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• 2002

The differential equations governing free vibrations of the elastic arches with unsymmetric axis are derived in rectangular coordinates rather than in polar coordinates, in which the effect of rotatory inertia is included. Frequencies and mode shapes are computed numerically for parabolic arches with both clamped ends and both hinged ends. Comparisons of natural frequencies between this study and SAP 2000 are made to validate theories and numerical methods developed herein. The convergent efficiency is highly improved under the newly derived differential equations in Rectangular coordinates. The lowest four natural frequency parameters are reported, with and without the rotatory inertia, as functions of three non-dimensional system parameters: the rise to chord length ratio, the span length to chord length ratio, and the slenderness ratio. Also typical mode shapes of vibrating arches are presented.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.1
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• pp.100-110
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• 2006

This paper presents the demagnetization and iron loss analysis of the single phase Flux Reversal Machine. It has a magnetic configuration similar to the switched reluctance machine but with multipole permanent magnets of alternate polarity on each stator salient pole embraced by concentrated coils. But it can be demagnetized by sudden over current and core losses increase because switching frequency is getting faster. This paper show demagnetization of permanent magnet and iron loss characteristic, and proposed a solution.

• Journal of Korean Society of Steel Construction
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• v.12 no.6
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• pp.639-648
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• 2000

A model analysis is used to predict the impact response of a simply supported elastic circular cylindrical shell composed of two bonded isotropic layers. The governing equations for a two-layered cylindrical shell are derived on the basis of an improved theory for the single-layer shell which includes the effects of transverse shear deformation and rotary inertia. Calculations are made for the specific case of the steel-concrete cylindrical shell subjected to a suddenly applied load. The solutions show that the method yields very good results. Therefore the proposed method is useful not only for a better investigating of the response characteristics of the shell but also available for a check on other numerical methods such a FEM.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1043-1052
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• 2014

This paper deals with in-plane free vibrations of the horseshoe circular arch. Simultaneous ordinary differential equations governing free vibration of the arch are derived with respect to the radial and tangential deformations. Particularly, differential equations are obtained under the arc length coordinate rather than the angular one in order to extend the horseshoe arch whose subtended angle is greater than ${\pi}$ radians. The differential equations are numerically solved for calculating the natural frequencies accompanying with the corresponding mode shapes. In parametric studies, effects of the rotatory inertia, slenderness ratio and circumferential arc length ratio on frequency parameters are extensively discussed.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.4
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• pp.225-234
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• 2003

Turbo compressors need high speed rotating impeller in structure, high rate gearbox and conventional induction motor. This mechanical system increased moment of inertia and mechanical friction loss. Recently turbo compressor has adopted a super high-speed motor and driver and have made its size smaller and mechanical friction loss at minimum. In this paper, variable super high - speed motor controller, compressor controller and MMI controller are implemented with only one DSP (TMS320VC33) chip for a 150HP, 70,000rpm direct drive turbo compressor. It was required hardware and software integration. The result of integration, Controller hardware became simple and all control software are developed same developing tool. The implements turbo compressor meets the requirements.

• Proceeding of KASS Symposium
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• 2008.05a
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• pp.74-79
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• 2008

In this study, impact transient responses of (Graphite/Epoxy) laminated composite subjected to low-velocity impact are investigated using a finite element method. Dynamic von-Karman plate equations considering large deflection of plate are modified to include the effect of transverse shear deformations as in Mindlin plate theory and also the rotary inertia effect is considered. The convergence of transient responses is used contact law established through the statical indentation test. We investigate displacements, contact forces and strains by thickness variation of various laminated composite. We compare and analyze each results.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.4
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• pp.149-155
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• 2016

This paper presents a control method of a mecanum wheel-based omni-directional electric board using driver weight shift. Instead of a steering device such as a joystick or a remote controller, 3 degree-of-freedom driving command for translational and rotational motion of the omni-directional electric board is generated from position of center of gravity measured from weight distribution. The weight shifting motion is not only a driving command but also an intuitive motion to overcome inertial forces. The overall control structure is presented with experimental results to prove validity of the proposed method.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.4 s.70
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• pp.385-393
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• 2005

This paper established the dynamic model of a flexible Timoshenko beam capable of geometrical nonlinearities subject to large overall motions by using the finite element method. Equations of motion are derived by using Hamilton principle and are formulated in terms of finite elements in which the nonlinear constraint equations are adjoined to the system using Lagrange multipliers. The Newmark direct integration method and the Newton-Raphson iteration are employed here for the numerical study which is to demonstrate the efficiency of the proposed formulation.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.4
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• pp.307-314
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• 2016

Energy flow analysis(EFA) is a representative method that can predict the statistical energetics of structures at high frequencies. Generally, as the frequency increases, the shear distortion and rotatory inertia effects in the out-of-plane motion of beams or plates become important. Therefore, to predict the out-of-plane energetics of coupled structures in the high frequency range, the energy flow analyses of Timoshenko beam and Mindlin plate are required. Unlike the energy flow model of Kirchhoff plate, the energy flow model of Mindlin plate is composed of three kinds of energy governing equations(out-of-plane shear wave, bending dominant flexural wave, and shear dominant flexural wave). This paper performed the energy flow finite element analysis(EFFEA) of coplanar coupled Mindlin plates. For EFFEA of coplanar coupled Mindlin plates, the energy flow finite element formulation of out-of-plane energetics in the Mindlin plate was performed. The general EFFEA program was implemented by MATLAB® language. For the verification of EFFEA of Mindlin plate, the various numerical applications were done successfully.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.6 s.46
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• pp.1-12
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• 2005

For a shear-deformable beam-column element subjected io non-conservative forces, equations of motion and a finite element formulation are presented applying extended Hamilton's principle. The influence of non-conservative force's direction parameter, internal and external damping forces, and shear deformation and rotary inertia effects on divergence and flutter loads of Beck's columns are intensively investigated based on element stiffness, damping and mass matrixes derived for the non-conservative system.