• Proceedings of the Korea Concrete Institute Conference
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• 1990.10a
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• pp.57-62
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• 1990

This paper is to study the effect of rectilinear confinement in high-strength concrete subjected to a monotonically increasing compressive axial loads. To investigate behavior of columns rectilinearly confined with lateral ties and longitudinal rebars, twelve specimens including two plain concrete specimens were tested. The main variables in this study are volumetric ratio of lateral ties, cistribution of lateral ties, yield strength of logitudinal steel, ratio of area of longitudinal steel to the area of cross section. The test results were not only compared with an empirical model for the stress-strain curve of rectilinearly confined high-strength concrete but also the existing model. The empirical model used calculating column capacity shows better agreement with the test results tham the existing model.

• Journal of Genetic Medicine
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• v.14 no.1
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• pp.31-33
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• 2017

Chromosomal loss in trisomy (trisomy rescue) to generate a disomic fetus can cause confined placental mosaicism and/or feto/placental mosaicism. After trisomy rescue event, there is a risk of fetal uniparental disomy (UPD). Noninvasive prenatal test (NIPT) reflects the genomic constitution of the placenta, not of the fetus itself. Feto-placental discrepancy can therefore cause false-positive (trisomy) NIPT results. These discordant NIPT results can serve as important clues to find UPD associated with confined placental mosaicism. We report a case with maternal UPD of chromosome 20, detected by NIPT of 1,000 high-risk pregnancies, carried out for detecting chromosomal abnormalities in Koreans.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.147-154
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• 2003

The purpose of this study is to investigate analytically the flexural behavior characteristics of Circular concrete beams confined by carbon sheet. Nonlinear analysis method is presented to simulate the structural behavior beam models. The proposed analytical hardening models were considered the confinement effect of concrete and the tensile effect of carbon sheet in tensile region of concrete. Prandtl-Reuss numerical formula was used to nonlinear analysis of finite element models. Comparisons analytical models with experimental data obtained from flexural testing in the laboratory were presented. Analytical and experimental models show similar behavior.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.199-204
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• 2003

The purpose of this study is to experimentally investigate the structural performance of concrete exterior beam-column joints confined by carbon sheet tube. Four specimens were produced with different numbers of carbon sheet and the other specimen was produced with reinforced concrete. A hydraulic dynamic actuator with 30tonf capacity was used to cyclic lateral loading test. The experimental results represent that the numbers of carbon sheet have an influence the load and displacement capacity. However, the bond length of carbon sheets for connecting beam and column has to be considered to improve the capacity of joint.

• Bulletin of the Korean Chemical Society
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• v.22 no.12
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• pp.1375-1379
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• 2001

Monte Carlo simulations of hard-spheres confined in parallel hard walls have been carried out extensively at various densities and for various wall distances. The compressibility factors in the directions parallel and normal to the wall have been calculated from the radial free space distribution function (RFSDF) with the results showing that the compressibility factors normal to the wall are smaller than those in parallel direction and that a solid phase is formed in the direction normal to the wall while a fluid phase remains in the parallel direction. An order parameter is found to classify the phases whether a system (or a molecule) is in a fluid or a solid state. The compressibility factors of narrow wall are very small compared to those when the wall is put away. A plausible mechanism of the rise of sap in xylem vessel has been proposed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.566-569
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• 2008

Recently, the biolistic process is emerging as an effective needle-free drug delivery technique to transfer adequate concentrations of pharmacologic agents to soft living tissues with minimum side effects. We have started developing an effective method for delivering drug coated particles using laser ablation. A thin metal foil with deposited micro-particles on one side is irradiated with laser beam on the opposite side so that a shock wave is generated. This shock wave travels through the foil and is reflected, which causes and instantaneous deformation of the foil. Due to such a sudden deformation, the micro-particles are ejected at a very high speed. Here we present the experimental results of direct and confined laser ablation, which correspond to the initial stage of the whole experiment.

• Structural Engineering and Mechanics
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• v.40 no.2
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• pp.215-231
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• 2011

The axial compressive strength of unidirectional FRP is generally quite lower than its axial tensile strength. This fact decreases the advantages of FRP as main load bearing member in engineering structure. In order to restrain the lateral expansion and splitting of GFRP, and accordingly heighten its axial compressive bearing capacity, a project that to confine GFRP pole with surrounding CFRP sheet is suggested in the present study. The Experiment on the CFRP sheet confined GFRP poles showed that a combined structure of high bearing capacity was attained. Basing on the experiment research a theoretical iterative calculation approach is suggested to predict the ultimate axial compressive stress of the combined structure, and the predicted results agree well with the experimental results. Then the influences of geometrical parameters on the ultimate axial compressive stress of the combined structure are also analyzed basing on this approach.

• Structural Engineering and Mechanics
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• v.35 no.3
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• pp.315-333
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• 2010

The structural behaviors of circular concrete filled steel tube (CFT) structures are investigated by nonlinear finite element method. An efficient three-dimensional (3D) degenerated beam element is adopted. Based on those previous studies, a modified stress-strain relationship for confined concrete which introduces the influence of eccentricity on confining stress is presented. Updated Lagrange formulation is used to consider the geometrical nonlinearity induced by large deformation effect. The nonlinear behaviors of CFT structures are investigated, and the accuracy of the proposed constitutive model for confined concrete is mainly concerned. The results demonstrate that the confining effect in CFT elements subjected to combining action of axial force and bending moment is far sophisticated than that in axial loaded columns, and an appropriate evaluation about this effect may be important for nonlinear numerical simulation of CFT structures.

• Computers and Concrete
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• v.24 no.3
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• pp.259-269
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• 2019

The work aims at the comparison among commonly used research programs concerning moment-curvature ($M-{\chi}$) diagrams of confined R.C. members. The software considered in this work are Sap2000, SeismoStruct and Opensees. The curves provided by these software, given the same modelling, have been compared to those provided by a theoretical fiber model. A parametric analysis has been led on rectangular column sections with different level of axial load and different stirrups spacing. The accuracy of the modelling of the considered structural programs has been investigated by comparing their results with those obtained by applying the theoretical fiber model.

• The Journal of Engineering Geology
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• v.30 no.4
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• pp.435-446
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• 2020

The use of groundwater in Korea has increased in recent years to the point where its extraction is restricted in times of drought. This work models the groundwater pumping field as a confined aquifer in a simplified simulation of groundwater flow. It proposes a genetic algorithm to maximize groundwater development using a conceptual model of a steady-state confined aquifer. Solving the groundwater flow equation numerically calculates the hydraulic head along the domain of the problem; the algorithm subsequently offers optimized pumping strategies. The algorithm proposed here is designed to improve a prior initial groundwater management model. The best solution is obtained after 200 iterations. The results compare the computing time for five simulation cases. This study shows that the proposed algorithm can facilitate better groundwater development compared with a basic genetic algorithm.