• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2210-2213
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• 2008

In the present study, effects of degree of confinement on heat transfer characteristics of a micro-scale slot jet impinging on a heated flat plate are experimentally investigated. The effects of Reynolds numbers (Re = $1000{\sim}5000$), lateral distances (x/B = $1{\sim}10$), nozzle-to-plate spacings (Z/B = $1{\sim}20$), and degree of confinement ($B_c$/B = 3, 48) on the Nusselt number are considered. The results show that the effects of the degree of confinement on the cooling performance of the micro-scale impinging slot jet are significant at lower nozzle-to-plate spacings and higher Reynolds numbers. In addition, it is shown that the cooling performance of the micro-scale unconfined slot impinging jet is 200% higher than that of the micro-scale confined slot impinging jet.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.937-942
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• 2003

Three series of 36 short circular columns confined by wraps, full shells and partial shells were tested by varying the thickness of GFRP laminates. An assessment of the effectiveness of the existing models on confinement of concrete columns with FRP was made for present tests. Test results indicated significant increases in strength and deformability compared with those in unconfined concrete, particularly warp and full shell confinement. Existing predictive equations for peak strength and strain of confined concrete showed a large scatter and varied considerably, resulting from the realistic fracture strains of FRP nor considered.

• Steel and Composite Structures
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• v.1 no.3
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• pp.313-328
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• 2001

This paper presents a three-dimensional finite element analysis methodology for a quantitative evaluation of confinement in concrete-filled box-shaped unstiffened steel columns. The confinement effects of concrete in non-circular sections can be assessed in terms of maximum average lateral pressure. A brief review of a previous method adopted for the same purpose is also presented. The previous method is based on a two-dimensional finite element analysis method involving a concrete-steel interaction model. In both the present and previous methods, average lateral pressure on concrete is computed by means of the interaction forces present at the concrete-steel interface. Subsequently, the strength enhancement of confined concrete is empirically related to the maximum average lateral pressure. The results of the former and latter methods are then compared. It is found that the results of both methods are compatible in terms of confined concrete strengths, although the interaction model yields a somewhat overestimated estimation of confinement than those of the present method when relatively high strength concrete is used. Furthermore, the confinement in rectangular-shaped sections is investigated and the reliability of previously adopted simplifications in such cases is discussed.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.29-34
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• 2001

An experimental study was conducted to investigate the effectiveness of transverse reinforcement in reinforced concrete tied columns subjected to monotonically increasing axial compression. Eighteen large-scale columns(260$\times$260$\times$120mm) were fabricated to simulate similarly an actual structural members size. Effects of main variables such as the concrete compressive strength, the tie configuration, the transverse reinforcement ratio, the tie spacing, and the spatting of the concrete cover were studied in this research program.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.547-552
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• 1998

Lateral pressure by circular reinforcement greatly enhances the maximum strength and ductility of spiral columns. The lateral confinement effects will be improves ductility of high-strength concrete. The major purpose of this paper is to study on the improvements of maximum strength and strain at that point of spiral concrete columns subject to axial loads. For this purpose, this study collected the other analytical results and the experimental data that has been performed by a lot of worldwide researchers and also analyzed it statistically. As the result, the theoretical equation for predict maximum strength and strain at that point was proposed. It is based on calculation of lateral confinement pressure generated by circular reinforcement, and the resulting improvements in strength and ductility of confined concrete.

• Structural Engineering and Mechanics
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• v.89 no.3
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• pp.323-334
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• 2024

Physical and chemical factors can cause traditional timber constructions to lose structural integrity. Knowing the dynamic properties of the building components is vital to avoid damage to the buildings from dynamic effects, a subset of physical effects. In this work, spruce and scotch pine wooden beams that had been strengthened in three distinct ways with carbon fiber strengthened polymer (CFRP) were investigated for changes in their dynamic properties. For this, CFRP was used to strengthening unstrengthened wooden beams in the form of bottom confinement, U-shaped confinement, and full confinement after the dynamic parameters of the beams were determined. By using experimental modal analysis with both free-free and fixed-fixed boundary conditions, the beams'initial natural frequencies were identified.

• Carbon letters
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• v.17 no.1
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• pp.29-32
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• 2016

This paper addresses the effect of dopants on the electronic properties of zigzag (8, 0) semiconducting single walled carbon nanotubes (SWCNTs), using extended Hückel theory combined with nonequilibrium Green’s function formalism. Through appropriate dopant concentrations, the electronic properties of SWCNTs can be modified. Within this context, we present our ongoing investigation on (8, 0) SWCNTs doped with nitrogen. Quantum confinement effects on the electronic properties of the SWCNTs have also been investigated. The obtained results reveal that the electronic properties of SWCNTs are strongly dependent on the dopant concentration and modification of electronic structures by hydrogen confinement.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.339-342
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• 2003

The bridge columns with lap-splice reinforcements in earthquake suffered a brittle bond-slip failure due to deterioration of the lap-spliced longitudinal reinforcements without developing its flexural capacity or ductility. In this case, such a brittle failure can be controlled by the seismic retrofit using FRP wrapping. The retrofitted columns using FRP wrapping showed significant improvement in seismic performance due to FRP's confinement effect. This paper presents the circumferential confinement effect of existing circular bridge pier strengthened with FRP wrapping for poor lap-splice details. The effects on the confinement of FRP wrapping, such as gap lengths between footing and FRP, fiber orientations, and thicknesses of FRP, were investigated by quasi-static experiments.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.280-287
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• 2003

The bridge columns with lap-splice reinforcements in earthquake suffered a brittle bond-slip failure due to the deterioration of lap-spliced longitudinal reinforcement without developing its flexural capacity or ductility. In this case, such a brittle failure can be controlled by the seismic retrofit using FRP wrapping. The retrofitted columns using FRP laminated circular tube showed significant improvement in seismic performance due to FRP's confinement effect. This paper presents the circumferential confinement effect of existing circular bridge pier strengthened with FRP wrapping for poor lap-splice details. The effects on the confinement of FRP wrapping, such as gap lengths between footing and FRP, fiber orientations, and thicknesses of FRP, were investigated by Quasi-static experiments.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.2
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• pp.451-457
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• 2017

The numerical analysis was conducted to evaluate the behavior of slab-column connection subjected to blast loads using LS-DYNA. The typical form of slab-interior column connection for analysis was considered as a reference specimen and the drop panel slab-interior column was designed to verify the effects of drop panel. The slab-column connections, which were composed of interior, edge and corner column, were additionally analyzed to compare their confinement effects of specimens. Analysis results were contained the failure shape of connection, behavior of member and so on. From the results, the blast-resistant capacities of slab-column connection would be enhanced by reinforcing the drop panel. In addition, the performance of connections could be improved, when the confinement effects were enhanced.