• Journal of the Korean Magnetics Society
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• v.10 no.1
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• pp.22-29
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• 2000

The effective linewidth was measured using the conventional cavity perturbation method at 9.43 GHz in room temperature for Ca-Zr substituted yttrium iron garnet plate. The experimental set-up consists of the network analyzer, the electromagnet and the cylimdrical TE001 cavity. Measurement was performed in the static magnetic field perpendicular to the sample plane. The real and imaginary parts of diagonal component of the microwave susceptibility tensor are obtained from the resonance frequency and the quality factor Q of the cavity. Variations of the effective linewidth was qualitatively explained with the spin wave scattering theory.

• Journal of KSNVE
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• v.7 no.2
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• pp.331-345
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• 1997

A theoretical formulation for the analysis of free vibration of clamped-free cylindrical shells with plates attached at arbitrary axial position(s) was completed and it was programed to get the numerical results which yield natural frequencies and mode shape of the combined system of the plate and the shells. The frequencies and mode shapes from theoretical calculation were compared with those of commercial finite element code, ANSYS. In order to validate the theory, modal test was also performed by impact test and FFT analysis. The results shows good agreement with those of ANSYS and test results in frequencies and mode shapes. The method developed herein is likely to be used for the analysis of the free vibration of the clamped-free circular cylindrical shells with any kinds of lids such as hollow circular plates, conical shells, spherical shells, or semi-spherical shells.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1229-1234
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• 2006

This paper is concerned with the dynamic modeling and controller design for a cylindrical shell equipped with MFC actuators. The dynamic model was derived by using Ravleigh-Ritz method based on Donnel-Mushtari shell theory. The boundary conditions at both ends were assumed to be shear diaphragm. To verify the theoretical results, a cylindrical shell structure made of aluminum was built ana tested by using impact hammer. Experimental results show that there are little discrepancies compared to theoretical results because of the boundary conditions at both ends. The MFC actuators were glued to the cylindrical shell in longitudinal and circumferential directions. The PPF controller were designed for lowest two modes and applied to the MFC actuators. The experimental results show that vibrations can be successfully suppressed.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.2
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• pp.67-78
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• 1994

This is a fundamental study aiming at scrutinizing the effect of reinforcement and deformation characteristics of soft clayey foundation improved by vanous technical treatments. Among many methods proposed thus far, geotextile was selected for the purpose of improvement of the model soil foundation on which plate loading test was subsequently performed. Loading test has been carried out with the variation of the location and number of covering layers of geotextile, and actual values for ground deformation and geotextile effect were secured. As for technique on deformation analysis, elasto-plastic model for soil, elastic model for sand, and beam theory for geotextile were coupled with satisfactory results between observed and numerical values.

• Structural Engineering and Mechanics
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• v.9 no.6
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• pp.541-555
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• 2000

Pultruded cross-sections are always thin-walled due to constraints in the manufacturing process. Thus, the buckling strength determines the overall strength of the member. The elastic buckling of pultruded angle sections subjected to direct compression is studied. The lateral-torsional buckling, very likely to appear in thin-walled cross-sections, is investigated. Plate theory is used to allow for cross-sectional distortion. Shear effects and bending-twisting coupling are accounted for in the analysis because of their significant role. A simplified approach for determining the maximum load of equal leg angle sections under compression is presented. The analytical results obtained in this study are compared to the manufacturer's design guidelines for compression members as well as with the design specifications for steel structural members. Experimental results are obtained for various length specimens of pultruded angle sections. The results presented in this paper correspond to actual pultruded equal leg angle sections being used in civil engineering structures.

• Structural Engineering and Mechanics
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• v.4 no.5
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• pp.485-496
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• 1996

This paper describes a numerical and experimental study on the stability and failure behaviour of rectangular symmetric laminated composite plates. The plates are simply supported along the unloaded edges and clamped along the loaded ends, and they are subjected to uniaxial in-plane compression. The finite element method was employed for the theoretical study. The study examines the effect of the plate's stacking sequence and aspect ratio on the stability and failure response of rectangular symmetric laminated carbon fibre reinforced plastics composite plates. The study also includes the effect of the unloaded edge support conditions on the postbuckling response and failure of the plates. Extensive experimental investigation were also carried out to supplement the finite element study. A comprehensive comparison between theory and experimental data are presented and discussed in this contribution.

• Structural Engineering and Mechanics
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• v.31 no.5
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• pp.481-506
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• 2009

The present study is concerned with the stochastic linear free vibration study of laminated composite plate embedded with piezoelectric layers with random material properties. The system equations are derived using higher order shear deformation theory. The lamina material properties of the laminate are modeled as basic random variables for accurate prediction of the system behavior. A $C^0$ finite element is used for spatial descretization of the laminate. First order Taylor series based mean centered perturbation technique in conjunction with finite element method is outlined for the problem. The outlined probabilistic approach is used to obtain typical numerical results, i.e., the mean and standard deviation of natural frequency. Different combinations of simply supported, clamped and free boundary conditions are considered. The effect of side to thickness ratio, aspect ratio, lamination scheme on scattering of natural frequency is studied. The results are compared with those available in literature and an independent Monte Carlo simulation.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.2
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• pp.79-91
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• 1992

This paper develops the compliance approach to the problem of load sharing between a cracked plate and a patch used to bridge the crack. The theory is validated by using calculated stress intensity factors for the patched and unpatched case to reduce experimentally observed growth rates to common base, Calculations are then made on the effect of patch dimension on fatique life technique. The optimum design of the patch considered the life expectancy and fracture strength of the cracked structure can be performed simply by using this technique.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.393-400
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• 2001

A simple numerical modelling technique is proposed for estimating the shear stress distribution in beams of framed tube structures with multiple internal tubes. The structures are analysed using a continuum approach in which each tube is individually modelled by a tube beam that accounts for the flexural and shear deformations, as well as the shear lag effects. The method idealises the discrete tubes-in-tube structures as an assemblage of equivalent multiple beams, each composed of orthotropic plate panels. The numerical analysis of shear stress is based on the elastic theory in conjunction with the minimum potential energy principle. By simplifying assumptions regarding the form of strain distributions in external and internal tubes, the shear stress distributions are expressed in terms of a series of linear functions of the second moments of area of the structures and the corresponding geometric and material properties, as well as the applied loads. The simplicity and accuracy of the proposed method are demonstrated through the solutions of three numerical examples.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.04a
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• pp.272-279
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• 1998

The purpose of this study is to show how to gain the morphology of the Hybrid Spatial Structures and to get the geometrical data such as node coordinates, member relationships and graphic images. To form spatial structures, we have developed morphological aspects of general spatial structures, programming process and techniques. Structural design has many processes. Especially, it is very important to consider the determination of structural configuration. Regular Hybrid Spatial Structures have complex configuration, so we need to make use of automated computer process to determine structural shape in Hybrid Spatial Structures. We have applied morphological aspects to double layer plate, single layer dome, double layer dome and tensegrity structure.