• 대한방사선방어학회:학술대회논문집
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• 2011.04a
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• pp.6-7
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• 2011

• Journal of the Korean Magnetics Society
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• v.8 no.2
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• pp.49-56
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• 1998

Explicit and closed-form expressions describing magnetic behaviors of uniaxial magnetic materials are derived. Explicit and closed-form expressions for magnetic torque, magnetization orientation, and thier derivative functions with respect to the intensity and the orientation of an applied field. Those explicit expressions could give elegant mehtods of measuring magnetic anisotropy and saturation magnetization by the least squre fitting. In addition, on could use them to study the distribution function of magnetic propeties of a non-interacting magnetic aggregate.

• Proceedings of the Korean Magnestics Society Conference
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• 1998.05a
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• pp.132-133
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• 1998

• Progress in Medical Physics
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• v.22 no.4
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• pp.190-197
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• 2011

Currently, the dose distribution calculation used by commercial treatment planning systems (TPSs) for high-dose rate (HDR) brachytherapy is derived from point and line source approximation method recommended by AAPM Task Group 43 (TG-43). However, the study of Monte Carlo (MC) simulation is required in order to assess the accuracy of dose calculation around three-dimensional Ir-192 source. In this study, geometry factor was calculated using segmented sources integration method by dividing microSelectron HDR Ir-192 source into smaller parts. The Monte Carlo code (MCNPX 2.5.0) was used to calculate the dose rate $\dot{D}(r,\theta)$ at a point ($r,\theta$) away from a HDR Ir-192 source in spherical water phantom with 30 cm diameter. Finally, anisotropy function and radial dose function were calculated from obtained results. The obtained geometry factor was compared with that calculated from line source approximation. Similarly, obtained anisotropy function and radial dose function were compared with those derived from MCPT results by Williamson. The geometry factor calculated from segmented sources integration method and line source approximation was within 0.2% for $r{\geq}0.5$ cm and 1.33% for r=0.1 cm, respectively. The relative-root mean square error (R-RMSE) of anisotropy function obtained by this study and Williamson was 2.33% for r=0.25 cm and within 1% for r>0.5 cm, respectively. The R-RMSE of radial dose function was 0.46% at radial distance from 0.1 to 14.0 cm. The geometry factor acquired from segmented sources integration method and line source approximation was in good agreement for $r{\geq}0.1$ cm. However, application of segmented sources integration method seems to be valid, since this method using three-dimensional Ir-192 source provides more realistic geometry factor. The anisotropy function and radial dose function estimated from MCNPX in this study and MCPT by Williamson are in good agreement within uncertainty of Monte Carlo codes except at radial distance of r=0.25 cm. It is expected that Monte Carlo code used in this study could be applied to other sources utilized for brachytherapy.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.10
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• pp.42-50
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• 2005

Based upon the derived analytical model and equation of motion for the general rotor system with anisotropic stator and asymmetric rotor treated as a periodically time-varying system, the series of equations are structured by associating with the time modulated coefficients. The frequency response functions (FRFs) expressed by physical parameters are derived in such a convenient way from the direct inverse matrices of the Fourier transformation of those series of equations, from which the characteristics are analyzed and the properties are suggested.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.1
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• pp.31-39
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• 1985

Using the tensor elastic Green functions an exact integral equation is formulated for two anisotropic precipitates embedded in an infinite anisotropic matrix; the matrix is subjected to an applied strain field or the precipitates undergo a stress-free transformation strain. This equation is reduced to an infinite system of algebraic equations by expanding the strains in Taylor series about the two points within each precipitate, and an approximation of the strain distributions within the two spherical precipitates is obtained by truncating the higher order terms. Since the present method requires no symmetry conditio between the two shperical precipitates, it is possible to obtain the strain distribution within the precipitates when the elastic constants and/or the sizes of the precipitates are different each other. The strains are expanded about arbitrary points, giving more accurate distributions of the strains than those presented elsewhere. The present method can be directly estended to the case of more than two spherical precipitates.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1998.11a
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• pp.303-308
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• 1998

암반을 대상으로 하는 건설공사는 많은 시간과 비용, 설계, 시공, 안전상에 많은 문제점을 일으키고 있다. 이러한 암반들은 흡수, 풍화 등에 기인하여 안정성이 약화되어 낙석, 산사태, 붕괴 등의 위험을 안고 있으며 이러한 현상은 우기, 해빙기에 두드러지게 나타나고 있다 비균질, 비등방성의 역학적 성질을 지닌 암석은 변형 거동을 완벽하게 예측하지는 못하고 있는 실정으로 이러한 거동은 암석의 종류와 구성 광물, 내부 불연속면의 상태, 응력 조건과 온도, 습도의 함수비등과 같은 다양한 요소에 의해 영향을 받으며, 이러한 경향은 퇴적암의 경우 두드러지게 나타나고 있다. (중략)

• Proceedings of the Korean Magnestics Society Conference
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• 1998.10a
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• pp.96-97
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• 1998

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.1
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• pp.29-37
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• 2007

This study deals with displacement analysis of anisotropic folded structures with triangular elements and quadrilateral elements. When folded plates are analyzed, triangular elements as well as quadrilateral elements are needed for conveniences of modelling. However, using triangular elements is not a simple problem. A simple formulation is presented which allows a quadrilateral element to degenerate into a triangular element. Therefore it can easily be used for computational simplicity and avoided complexities on mixed use of triangular element and quadrilateral element. In this paper, a high-order shear deformation theory using only Lagrangian interpolation functions and drilling degrees of freedom for folded plates are utilized for more accurate analysis. Especially, various results of anisotropic laminated and folded composite structures with triangular element and quadrilateral element show the structural behavior characteristics of them.

• Journal of the Korean Magnetics Society
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• v.15 no.2
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• pp.118-124
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• 2005

We have obtained sharp and clearly resolved ESR spectra of $Nd^{3+}$ and $Er^{3+}$ in vapor transport equilibrium (VTE) treated $LiNbO_3$ crystals, consequently have determined more accurate spin Hamiltonian parameters, than those in congruent samples. The anisotropic hyperfine structures of $^{143}Nd^{3+}$ and $^{145}Nd^{3+}$ in the VTE-treated crystals at liquid helium temperature have been analyzed. It is proposed that both rare earth ions favor the lithium site in $LiNbO_3$ from the consideration of the determined anisotropic g-values.