• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.4
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• pp.366-371
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• 1988

A parallel-plate waveguide with a slit in its upper plate is analysed. An integral equation is formulated for the equivalent magnetic current and solved by the conventional moment method. Numerical results are presented for the magnetic current, reflection and transmission coefficients, a normalized radiated power in the slit, and equivalent circuit parameters. The equivalent circuit parameters are an useful quantities in the study of the E-plane coupled microstrip antennas.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.4 no.1
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• pp.3-9
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• 1993

A new method is developed for analysis of the electromagnetic coupling to an angled two-strip transmission line. It consists of solving the cylindrical transmission line equations an- alytically, and then adjusting the involved parameters to support the cylindrical TEM mode along its equivalent model of the angled two-plate transmission line. Its analytic solution agrees with the numerical value obtained by using the circuit-concept approach.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.1
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• pp.39-46
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• 2000

An analysis of the free vibration for the metal-piezoceramic laminated thin plates is described. The purpose of this study is to develop a equivalent method for the free vibration analysis of metal-piezoce-ramic laminated thin plate which are not sysmmetric about the adhered layer and the piezoelectric effect. In order to confirm the validity of the vibration analysis, double Fourier sine series is used as a modal displacement function of a metal-piezoceramic laminated thin plate and applied to the free vibration analysis of the plate under various boundary conditions.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.398-404
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• 1998

The acoustic power reduction methods of the vibrating structures are valid to design the quite structure. To calculate the acoustic power, the dynamic responses have to be determined. It is not easy to analyse the structure composed of the corrugated panels. Because of the structural complexity and the many analysing times. To make up for these defects, the equivalent orthogonal panel is presented. Also the acoustic power prediction method of the vibrating structures is proposed. As examples, the equivalent material properties of the corrugated plates are obtained and the acoustic powers of the floor structure are calculated at several frequency regions for KHST.

• The Journal of Korean Society for Radiation Therapy
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• v.19 no.1
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• pp.51-54
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• 2007

Purpose: Total body irradiation is used to kill the total malignant cell and for immunosuppression component of preparatory regimens for bone-marrow restitution of patients. Beam spoiler is used to increase the dose to the superficial tissues. This paper finds the property of the distance between beam spoiler and patient. Materials and Methods: Set-up conditions are 6 MV-Xray, 300 MU, SAD = 400 cm, field size = $40{\times}40cm^2$. The parallel plate chamber located in surface, midpoint and exit of solid water phantom. The surface dose is measured while the distance between beam spoiler and patient is altered. Because it should be found proper distance. The solid water phantom is fixer and beam spoiler is moving. Results: Central dose of phantom is 10.7 cGy and exit dose is 6.7 cGy. In case of distance of 50 cm to 60 cm between beam spoiler and solid water phantom, incidence dose is $14.58{\sim}14.92cGy$. Therefore, The surface dose was measured $99.4{\sim}101%$ with got near most to the prescription dose. Conclusion: In clinical case, distance between beam spoiler and patient affect surface dose. If once $50{\sim}60cm$ of distance between beam spoiler and patient, surface dose of patient got near prescription dose. It would be taken distance between beam spoiler and patient into account in clinical therapy.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5A
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• pp.649-656
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• 2008

The enhancement of the service life of damaged or cracked structures is a major issue for researchers and engineers. The hierarchic void element based on the integrals of Legendre polynomials is used to characterize the fracture behaviour of unpatched crack as well as repaired crack with bonded composite patches by computing the stress intensity factors and stress contours at the crack tip. Since the equivalent single layer approach is adopted in this study, the proposed element is necessary to represent a discontinuous crack part as a continuum body with zero stiffness. Thus the aspect ratio of this element to represent the crack should be extremely slender. The sensitivity of numerical solution with respect to energy release rate, displacement and stress has been tested to show the robustness of zero stiffness element as the aspect ratio is increased up to 2000. The stiffness derivative method and displacement extrapolation method have been applied to calculate the stress intensity factors of Mode I problem. It is noted that the proposed hierarchical void element can be one of alternatives to analyze the patched crack problems.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.2
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• pp.189-196
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• 2009

This paper presents the subparametric finite element model formulated by partial-linear layerwise theory for the analysis of laminate composites. The proposed model is based on refined approximations of two dimensional plane for orthotropic thick laminate plate as well as thin case. Three dimensional problem can be reduced to two dimensional case by assuming piecewise linear variation of in-plane displacement and a constant value of out-of-plane displacement across the thickness. The integrals of Legendre polynomials are chosen to define displacement fields and Gauss-Lobatto numerical integration is implemented in order to directly obtain maximum values occurred at the nodal points of each layer without other extrapolation techniques. The validity and characteristics of the proposed model have been tested by using orthotropic multilayered plate problem as compared to the values available in the published references. In this study, the convergence test has been carried out to determine the optimal layer model in terms of central deflection and stresses. Also, the distribution of displacements and stresses across the thickness has been investigated as the number of layer is increased.

• Journal of Radiation Protection and Research
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• v.8 no.1
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• pp.26-32
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• 1983

A somewhat detailed energy spectra in terms of the track length resulting from coupled electron-photon slowing down are calculated throughout the ICRU standard tissue with uniformly distributed gamma sources of $^{60}Co\;and\;^{137}Cs$, respectively. The calculation was accomplished by utilizing the latest available cross-section data as input to a carefully optimized computer code. In this report, the calculational method is described in detail. Furthermore, results of calculations are given in graphical form. The results show that the energy spectrum defined in terms of differential track length has about same shape although the energies of gamma source are different. The discontinuity in the energy spectrum appears at the energy of $T=(1/T_0+2/m_0c^2)^{-1}$, because a primary photon can not be degrade to a point below this energy.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.8
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• pp.899-904
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• 2014

Thickness profiled blank is designed using optimization techniques for maximizing the bulged heights during the free bulging of Inconel 718. The thickness of the blank was described by the Bezier curve and the locations of the control points were used as the design variables for optimization. The maximization of the bulged heights within the limited strain range served as the objective function and constraints for optimization. The equivalent static loads method for non-linear static response structural optimization (ESLSO) was used and the result of the optimization revealed 22 increased bulged heights. A free bulging test using a blank with an optimized profile was conducted to verify the optimization process. The results were compared with those of numerical analysis in terms of bulged height and deformed shape.

• Composites Research
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• v.18 no.5
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• pp.15-20
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• 2005

In this paper, damage induced acoustic emission in the composite plate in numerically simulated by using the three dimensional finite element method and explicit time integration. Acoustic source is modeled by equivalent volume source. To verify the proposed method, dynamic displacements due to the elastic wave are compared with the experiment when the fiber is broken in the single fiber embedded isotropic plate. For the laminated composite plates, the results are compared between homogenized model and DNS approach which models fibers and matrix separately. To capture high frequencies in the elastic wave, small time step size and a large number of meshes are required. The parallel computing technology is introduced to solve a large scale problem efficiently.