• Progress in Medical Physics
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• v.9 no.1
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• pp.37-46
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• 1998

Beta-particle energy distributions of the radionuclides in medicine are calculated for the medical physics applications. The radial component solutions of Dirac wave equations are evaluated for a point-nucleus un screened Coulomb potential. The WKB method is employed to correct the screening due to the orbital-electron cloud. Fierz interference terms are ignored. The radionuclides considered are $\^$32/P, $\^$90/Y, $\^$131/I, $\^$166/Ho, $\^$192/Ir, $\^$198/Au, $\^$153/Sm, $\^$169/Er and $\^$188/Re. A total of 9 beta-spectra for the radionuclides, currently in domestic use or potential use in the near future, are calculated with enough accuracy and presented in graphs and tables.

• Journal of Korean Society of Steel Construction
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• v.8 no.3 s.28
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• pp.55-65
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• 1996

For stability analysis of stifened rectangular thin plates with various boundary conditions, Ritz method is presented. An energy method is especially useful in those cases where a rigorous solution of the diferential eqution is unknown or where we have a plate reinforced by stiffeners and it is required to find only an approximate value of the critical load. The strain energy due to the plate bending and the work done by the in-plane forces are taken into account in order to apply the principle of the minimum potential energy. The buckling mode shapes of flexural beams with various boundary conditions are derived, and shape functions consistent with the given boundary conditions in the two orthogonal directions are chosen from those displacement functions of beams. The matrix equations for stability of stiffened rectangular thin plates are determined from the stationary condition of the total potential energy. Numerical example for stability behaviors of horizontally and vertically stiffened plates subjected to uniform compression, bending and shear loadings are presented and the obtained results are compared with other researchers' results.

• Nuclear Engineering and Technology
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• v.34 no.2
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• pp.154-164
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• 2002

Neutron cross section data on Dy-160, Dy-161, Dy-162, Dy-163 and Dy-164 were calculated and evaluated in the energy range of 1 keV to 20 MeV using a spherical optical model, statistical model and pre-equilibrium model. The energy dependent optical model potential parameters were obtained based on the recent experimental data. The width fluctuation correction in Hauser-Feshbach particle decay and the quantum mechanical approach in pre-equilibrium analysis were introduced and gave a better cross section calculation in EMPIRE-II. The total, elastic scattering and threshold reaction cross sections were evaluated and compared with the evaluated files. The model calculated (n, tot), (n, ${\gamma}$) and (n, p) cross sections were in good agreement with the experimental data in the measured energy range. The results will be applied to ENDF/B-VI for data improvement.

• Journal of the Korean Solar Energy Society
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• v.40 no.4
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• pp.1-11
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• 2020

The Journal of the Korean Solar Energy Society is the first journal in South Korea that adopts wind energy as one of its subjects. Since 2000, more than 140 papers on wind energy have been published in the journal, which accounts for 8.5% of the total publication. However, in recent years, the number of published papers on wind energy has been decreasing steadily, and a reason for this decline is the significant dependence on a few specific institutions and authors. In this study, wind energy subjects were classified using the frequency analysis of the subject words extracted from the title, keywords, and abstract of wind energy papers using the text mining technique. In addition, the Korea Citation Index was used to perform quantitative level evaluation by subject and institution and to analyze the trends and characteristics of the wind energy field. Therefore, it was identified that in terms of the number of publications and citations, the main subject areas were resource/micrositing and policy/potential.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.303-308
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• 2002

A governing differential equation (GDE) of PSC flexural member with constant eccentricity considering the long-term losses including concrete creep, shrinkage, and PS steel relaxation is derived based on the two approaches. The first approach utilizes the force and moment equilibrium equations derived based on the geometry of strains of the uniform and curvature strains while the second one utilizes the principle of minimum total potential energy formulation. The identity of the two GDE's is verified by comparing the coefficients consisting of the GDE's. The boundary conditions resulting from the functional analysis of the variational calculus are investigated. Rayleigh-Ritz method provides a way to get the explicit form of the continuous deflection function in which the total potential energy is minimized with respect to the unknown coefficients consisting of the trial functions. As a closure, the analytically calculated results are compared with the experiments and show good agreements.

• Structural Engineering and Mechanics
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• v.13 no.5
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• pp.533-542
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• 2002

This paper considers the buckling and post-buckling behavior of empty metal storage tanks under wind load. The structures of such tanks may be idealized as cantilever cylindrical shells, and the structural response is investigated using a computational model. The modeling employs a doubly curved finite element based on a theory by Simo and coworkers, which is capable of handling large displacements and plasticity. Buckling results for tanks with four different geometric relations are presented to consider the influence of the ratios between the radius and the height of the shell (R/L), and between the radius and the thickness (R/t). The studies aim to clarify the differences in the shells regarding their imperfection-sensitivity. The results show that thin-walled short tanks, with R/L = 3, display high imperfection sensitivity, while tanks with R/L = 0.5 are almost insensitive to imperfections. Changes in the total potential energy of tanks that would buckle under the same high wind pressures are also considered.

• Steel and Composite Structures
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• v.6 no.4
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• pp.319-333
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• 2006

A rectangular plate made of a porous material is the subject of the work. Its mechanical properties vary continuously on the thickness of a plate. A mathematical model of this plate, which bases on nonlinear displacement functions taking into account shearing deformations, is presented. The assumed displacement field, linear geometrical and physical relationships permit to describe the total potential energy of a plate. Using the principle of stationarity of the total potential energy the set of five equilibrium equations for transversely and in-plane loaded plates is obtained. The derived equations are used for solving a problem of a bending simply supported plate loaded with transverse pressure. Moreover, the critical load of a bi-axially in-plane compressed plate is found. In both cases influence of parameters on obtained solutions such as a porosity coefficient or thickness ratio is analysed. In order to compare analytical results a finite element model of a porous plate is built using system ANSYS. Obtained numerical results are in agreement with analytical ones.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.241_242
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• 2009

This paper presents a method to assess total transfer capability (TTC) by using energy function. To get the critical energy, the potential energy boundary surface(PEBS) method which is one of the transient energy function(TEF) method is used. TTC assessment is to calculate TTC by using the repeated power flow (RPF) method. It is seen that energy margin can be use to assess available transfer capability(ATC).

• Structural Engineering and Mechanics
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• v.31 no.6
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• pp.625-638
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• 2009

Applications of membrane mechanisms are widely found in nano-devices and nano-sensor technologies nowadays. An alternative approach for large deflection analysis of the orthotropic, elliptic membranes - subject to gravitational, uniform pressures often found in nano-sensors - is described in this paper. The material properties of membranes are assumed to be orthogonally isotropic and linearly elastic, while the principal directions of elasticity are parallel to the coordinate axes. Formulating the potential energy functional of the orthotropic, elliptic membranes involves the strain energy that is attributed to inplane stress resultant and the potential energy due to applied pressures. In the solution method, Rayleigh-Ritz method can be used successfully to minimize the resulting total potential energy generated. The set of equilibrium equations was solved subsequently by Newton-Raphson. The unparalleled model formulation capable of analyzing the large deflections of both circular and elliptic membranes is verified by making numerical comparisons with existing results of circular membranes as well as finite element solutions. The results are found in excellent agreements at all cases. Then, the parametric investigations are given to delineate the impacts of the aspect ratios and orthotropic elasticity on large static tensions and deformations of the orthotropic, elliptic membranes.

• Journal of the Korean Solar Energy Society
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• v.36 no.4
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• pp.21-29
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• 2016

Commercial wind farm design tools and the national wind map are used to determine the implementation potential of offshore wind power in Korea in this study. For this, the territorial waters of Korea were divided into nine analysis regions and a commercial CFD code was used to obtain wind resource maps at 100m A.S.L. which is the hub height of a 5MW wind turbine used in this study. With the wind resource obtained, factors including water depth, distance from substations, minimum and maximum capacity of a wind farm, distance between turbines and wind farms were considered to determine wind power potential. Also, the conservation areas, military zones, ports, fishing grounds, etc. were considered and excluded. As the result, a total capacity of 6,720 MW was found to be the implementation potential and this corresponds to $3.38MW/km^2$ in API. Also if the distance from the substation is not considered, the potential increased to be 10,040 MW. This offshore wind farm potential is considered enough to satisfy the target of wind farm capacities in the 7th national plan for electricity demand and supply.