• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.3
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• pp.111-118
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• 2002

In this paper, FEM analysis is performed in order to estimate the behavior of RC columns retrofitted with Carbon Fiber Sheet(CFS). Two node truss element and four node isometric plate bond element are used for modeling the CFS and the adhesion between concrete and CFS, respectively. Five specimens with different quantity of CFS are analyzed and compared with experimental results. From the comparison, analytical results show a good agreement with the test results. Therefore, it is advisable to use the FEM used in this paper to predict the behavior of columns with CFS.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.383-386
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• 1988

In MOS integrated circuits, annealing after oxidation process is necessary to improve physical properties of silicon dioxide. With subsequent annealing in inert gases such as nitrogen or argon, and excess silicon bond is allowed time to complete the oxidation and surface charge density is reduced. In this paper, we will present effects of the rapid thermal annealing on silicon dioxide. In order to evaluate characteristics of silicon dioxide, we analyzed C-V curve dependent on annealing time and temperature, and presented variation of fixed oxide charge.

• Ceramist
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• v.21 no.2
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• pp.29-37
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• 2018

In order to overcome the problems of existing low-dimensional materials (carbon nanotubes, graphene, transition metal dichalcogenides, etc) researches on new 1D materials have been studied. In the case of $LiMo_3Se_3$ and $Mo_6S_{9-x}I_x$, continuous researches have been carried out for 3D bulk synthesis and atomic scale dispersion. Recently, quantum confinement effect of $LiMo_3Se_3$ and bio-stability of $Mo_6S_{9-x}I_x$ have been proven and various applications have started to be studied. In addition, device application results using new 1D materials such as $Sb_2Se_3$ (optoelectronic devices using the property of effectively reducing exciton decay due to no dangling bond) and $VS_4$ (electrochemical energy storage using the space between 1-D nanostructures) have been reported very importantly. Therefore, it can be claimed that it has reached a very important time to find and synthesize new 1D materials and to report various characteristics not existing.

• Journal of the Korean Chemical Society
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• v.32 no.6
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• pp.567-574
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• 1988

Kinetic studies on the vanadium(IV)-catalyzed oxidation of dimethylsulfoxide by hydrogen peroxide in water and aqueous methanol and ethanol show that the reaction is the first order in the concentration of dimethylsulfoxide and hydrogen peroxide, respectively. Activation parameters are also measured for the oxidation of dimethylsulfoxide. It is suggested that the rate determining step is a process involving oxidation of dimethylsulfoxide as the result of nucleophilic attack by the sulfur on the O-O bond of vanadium(V)-peroxide complex.

• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.153-158
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• 2012

The hydrogenation of $AlB_2$-type BaGaGe exhibits a metal to insulator (MI) transition, inducing a puckering distortion of the original hexagonal [GaGe] layers. We investigate the electronic structure changes associated with the hydrogen-induced MI transition, using extended H$\ddot{u}$ckel tight-binding band calculations. The results indicate that hydrogen incorporation in the precursor BaGaGe is characterized by an antibonding interaction of $\pi$ on GaGe with hydrogen 1s and the second-order mixing of the singly occupied antibonding $\pi^*$ orbital into it, through Ga-H bond formation. As a result, the fully occupied bonding $\pi$ band in BaGaGe changes to a weakly dispersive band with Ge pz (lone pair) character in the hydride, which becomes located just below the Fermi level. The Ga-Ge bonds within a layered polyanion are slightly weakened by hydrogen incorporation. A rationale for this is given.

• Transactions of Materials Processing
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• v.25 no.5
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• pp.313-318
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• 2016

The plasma vapor coatings on two kinds of die steels have been carried out in order to identify the most optimized conditions. When TiN or TiAlN coatings were carried out on the substrates, the coating layer thicknesses were not significantly changed, and the optimized coating thickness was identified as ~ 5 μm. When the optimized coating conditions and stress analysis were applied to the primary piston dies for fabrication of aluminum cylinders, an extended life time of the die was observed. The methodology for extending the life time of dies was discussed in terms of microstructures and stress analysis.

• Journal of Welding and Joining
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• v.20 no.5
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• pp.99-105
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• 2002

One of the important advantage of adhesive bonded joint can combine the different materials. The joint that bonded by structural adhesive bond must keep a large force and its strength is affected by some environmental factors such as temperature and submergence time in water. In order to advance the fatigue strength of adhesive bonded joint, mostly put a surface treatment on the surface. This study was researched the effect of air temperature, submergence time, submergence temperature and surface treatment on the fatigue strength. We found that submergence temperature has the most effect and low plasma treatment specimens have the most fatigue strength.

• International Journal of Concrete Structures and Materials
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• v.7 no.4
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• pp.253-264
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• 2013

A major difference between high-strength reinforcing steel and conventional steel in concrete is that the service-load steel stress is expected to be greater. Consequently, the service-load steel strains are greater affecting cracking behavior. A parametric study investigating crack widths and patterns in reinforced concrete prisms is presented in order to establish limits to the service-load steel stress and strain. Additionally, based on the results of available flexural tests, crack widths at service load levels were evaluated and found to be within presently accepted limits for highway bridge structures, and were predictable using current AASHTO provisions. A limitation on service-level stresses of $f_s{\leq}414$ MPa (60 ksi) is nonetheless recommended.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.4
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• pp.153-160
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• 2001

In order to analyze the degradation process of epoxy/glass fiber for outdoor condition, FRP laminate was exposed to high temperature. Then, the degradation process was evaluated by comparing contact angle, surface potential, surface resistivity, and XPS. The experimental results showed that the amount of weight loss, contact angle, surface potential and surface resistivity increased up to 200 $^{\circ}C$ as a function of temperature. These phenomena show the existence of hydrophobic surface. With the change to the hydrophobic surface and the electrical potential and resistivity on FRP surface increased. In XPS to analyze surface chemical structures, the increased hydrophobicity in thermal increase of unsaturated double bond in carbon chains. Aslo, thermal treatment caused the discoloration on the point of treated surface. These phenomena were attributed to the generations of ether group.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.895-900
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• 2010

In order to find a relationship between firefly luciferases structure and bioluminescence spectra, we focus on excited substrate geometries which may be affected by rigid luciferases. Density functional theory (DFT) and time dependent DFT (TDDFT) were employed. Changes in only six bond lengths of the excited substrate are important in determining the emission spectra. Analysis of these bonds suggests the mechanism whereby luciferases restrict more or less the excited substrate geometries and to produce multicolor bioluminescence.