• Steel and Composite Structures
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• v.17 no.3
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• pp.305-320
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• 2014

The lowest critical value of the compressive force acting in the plane of symmetrically laminated quasi-isotropic thin rectangular plates is investigated. The critical buckling loads of plates with different types of lamination and aspect ratios are parametrically calculated. Finite Differences Method (FDM) and Galerkin Method are used to solve the governing differential equation for Classical Laminated Plate Theory (CLPT). The results calculated are compared with those obtained by the software ANSYS employing Finite Elements Method (FEM). The results of Galerkin Method (GM) are closer to FEM results than those of FDM. In this study, the primary aim is to conduct a parametrical performance analysis of proper plates that is typically conducted at preliminary structural design stage of composite vessels. Non-dimensional values of critical buckling loads are also provided for practical use for designers.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.1
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• pp.3-9
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• 1995

An isotropic electric-field probe, capable of characterizing and quantifying electromagnetic field, was fabricated. The probe consists of three short dipole antennas, a beam-lead Schottky diode and the high resistive transmission line. In order to get the isotropic response three mutually orthogonal dipoles are configured to form the probe. The probe's short dipole elements allow measurements of electric fields from 300MHz to 2GHz with a flatness of .+-. 2.9dB. The mutually orthogonal dipole configration shows a .+-. 1.2dB deviation in the isotropic response with respect to angle.

• Journal of the Korean Society of Marine Environment & Safety
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• v.11 no.1 s.22
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• pp.29-37
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• 2005

The design and development if Resonant-type Magnetometer(RM) using isotropic magnetic with high permeability is described in this paper. At first, the relationship between the inductance L if the coil winding on a magnetic material and the permeability u(H) appearing in the magnetic material with isotropic and high permeability is defined as a background theory. Then the circuit if RM, which is to obtain the values if L as the change qf frequency is implemented using simple Schmitt Trigger Circuit Through the swinging tests, which is to evaluate the measurement ability if RM, the measurement possibility for the component of earth field was confined.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1991.10a
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• pp.5-14
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• 1991

The basic rules and principles for designing structures with composite materials are briefly and intensively presented. The proposed design steps are explained. For preliminary design, use of quasi-isotropic properties is proposed. The validity of this proposal will be reported by separate papers.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.9
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• pp.919-925
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• 2011

In this paper, we designed and analyzed a 3D isotropic bulk structure consisting of thin wires and SRR's(Split Ring Resonator) with which the permittivity and permeability can be controlled at the same time. For the 3D isotropic bulk structure, first of all, the geometry seen by three main axes must look alike. Thus, we adopted the orthogonal thin wires and symmetrical SRR's. As a result, we constructed metamaterial bulk structures of which effective relative permittivity and permiability are about -0.6 and -1.5, respectively. Its refractive index is about -0.95 in each direction(x, y and z direction). The computed Brillouin dispersion diagram also showed that the proposed structure is almost near isotropic.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.9
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• pp.2162-2171
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• 1993

Geneal Structure optimization is utilized to minimize the weight of structures while satisfying constraints imposed on stress, displacements and natural frequencies, etc. Sandwich structures consist of inside core and outside face sheets. The selected sandwich structures are isotropic sandwich beams and isotropic sandwich plate. The face sheets are treated as membrane and assumed to carry only tensions, while the core is assumed to carry only transverse shear. The characteristic of the varying area are considered by adding the projected component of the tension to the transverse shear. The bending theory and energy method are adopted for analyzing sandwich beams and plates, respectively. In the optimization process, the cost function is the weight of a structure, and a deflection and stress constraints are considered. Design variable are thickness and tapering coefficients which determine the shape of a structure. An existing optimization code is used for solving the formulated problems.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1991.10a
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• pp.115-120
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• 1991

At the preliminary design stage, the orientations of laminae in a laminate are not known. This fact discourages the most of engineers from the beginning. If the quasi-isotropic constants are used, it halps the design engineer greatly to start his work. If conventional mechanics and elasticity theories can be used, the effort for design and analysis is greatly reduced. This paper reports the possibility of using the classical mechanics at the preliminary design stage for the laminated composite primary structure for civil construction. The result is quite promissing.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.339-340
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• 2008

This paper presents a novel design of the printed hyperpolar-transformed Sierpinski Carpet (HSC) antenna. By hyperpolar transforming the Sierpinski carpet geometry, from isotropic scaling symmetry to equiangular scaling symmetry, we get improved performance rather than that of the general Sierpinski Carpet antenna. The design parameter and performance of the proposed monopole antenna are investigated by simulation. And we showed that proposed HSC geometry gives more freedom for wideband antenna design such as flare angle, (angular)scale factor.

• Tunnel and Underground Space
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• v.15 no.4 s.57
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• pp.288-295
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• 2005

Many mechanical defects originated from various geological causes make rock mass exhibit anisotropic characteristics. Understanding how the stress distribution occurs in anisotropic rock mass is, therefore, very important for the design of footings on rock and rock structures. In this study, the patterns of elastic stress distribution, developed by acting line load on the surface, in transversely isotropic was investigated. The influence of joint stiffness, joint spacing, and dip angle on the stress distribution was examined. By assuming the Mohr-Coulomb criterion as joint slip condition, the development of joint slip zone was also discussed.

• Advances in Computational Design
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• v.5 no.3
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• pp.305-321
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• 2020

In this paper is presented the solution method for three-dimensional problem of transversely isotropic body's elastoplastic deformation by the finite element method (FEM). The process of problem solution consists of: determining the effective parameters of a transversely isotropic medium; construction of the finite element mesh of the body configuration, including the determination of the local minimum value of the tape width of non-zero coefficients of equation systems by using of front method; constructing of the stiffness matrix coefficients and load vector node components of the equation for an individual finite element's state according to the theory of small elastoplastic deformations for a transversely isotropic medium; the formation of a resolving symmetric-tape system of equations by summing of all state equations coefficients summing of all finite elements; solution of the system of symmetric-tape equations systems by means of the square root method; calculation of the body's elastoplastic stress-strain state by performing the iterative process of the initial stress method. For each problem solution stage, effective computational algorithms have been developed that reduce computational operations number by modifying existing solution methods and taking into account the matrix coefficients structure. As an example it is given, the problem solution of fibrous composite straining in the form of a rectangle with a system of circular holes.