• Analytical Science and Technology
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• v.31 no.1
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• pp.1-6
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• 2018

We used differential scanning calorimetry and a thermogravimetric analysis to investigate the effect of being confined in mesoporous MCM-41 on the decomposition of lithium borohydride and magnesium borohydride when heated. The confinement did not cause a phase transition of the metal borohydrides inside MCM-41, but did lower their decomposition temperature. With the exception of a lowering of the temperature, the decomposition reaction mechanism of the metal borohydrides was nearly the same for both the bulk and confined samples.

• The Pure and Applied Mathematics
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• v.6 no.2
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• pp.113-120
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• 1999

This paper studies the problem of an infinite confined aquifer which at time t ＜ 0 is assumed motionless. At time t = 0 crude oil seeps into the aquifer, thereby contaminating the valuable drinking water. Since the crude oil and water are im-miscible, the problem is posed as a one-dimensional two-phase unsteady moving boundary problem. A similarity solution is developed in which the moving front parameter is obtained by Newton-Ralphson iteration. A numerical scheme, involving the front tracking method, is devised employing the fourth order Runge-Kutta method. Comparison of the exact and numerical schemes shows an error of only 3%. Thus the developed numerical scheme is quite accurate in tackling more realistic problems where exact solutions are not possible.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.1
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• pp.161-168
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• 2001

The use of composite members to improve the compressive strength of steel structure is a common practice these days and its efficiency has already been proved by several researches and experiments. The result of concrete filled circular tubular(CFCT) stub column tests is introduced in this paper. The main parameter of this test is the ratio of diameter to thickness of circular hollow section. From the test results, the effect of concrete filled in steel tube on the ultimate strength, the deformation capacity and initial stiffness are discussed. The purpose of this paper is to investigate the effect of various parameters and evaluate the compressive strength of confined concrete. It would contribute to a better understanding of CFT structure, further laboratory experimentations are needed for better accurate estimation on its effect.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.4
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• pp.141-148
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• 2000

Recently the Carbon Fiber Sheet(CFS) is widely used for strengthening damaged RC structures. Strengthening compression members such as column can increase ductility and strength due to the confinement effect. In this experiment, the behavior of concrete cylinders confined by CFS was examined. The confinement pressure is increased linearly as axial stress is increased in low axial stress, and the confinement effect of CFS was rapidly developed after near maximum axial stress, thus axial strength and ductility was improved. As the ratio of CPS is increased, concrete cylinders failed due to local fracture of CFS. The confinement effect of circular section is more efficient than that of rectangular section. And significant improvement of axial strength, axial strain, transverse strain at failure is observed in circular section. This is because in rectangular section the local fracture of CFS near corner may be occured, thus the strain efficiency ratio must be considered for RC structures with CFS.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.67-67
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• 2003

Filamentous actin (F-actin) is a two stranded long helix that performs structural function in eukaryotic cells. F-actin had been assembled from Alexa-labeled G-actin and had been confined in microchannel. The fluctuation of single filaments was observed by fluorescence optical microscopy. We measured Tangent-tangent Correlation Function G(s) (where s is the distance along the contour of the chain), which tells us the confining wall effect of wormlike semi-flexible polymers as well as the flexural rigidity, such as persistence length.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1007-1013
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• 2004

A new type of girder named as Steel-Confined Prestressed Concrete Girder(SCP Girder) has been developed, which is composed of concrete, steel plate, and prestressing tendon. This girder may maximize structural advantages of these components, therefore it can be used to construct the middle or long span bridge with low-height girder. To verify the propriety of design, structural safety, and applicability of this girder, static load test was carried out. In this study, a design program was developed for practical design of railway bridge using SCP girder. And to verify the applicability of SCP girder to railway bridge, structural performance and economic efficiency based on the construction cost were compared with conventional railway bridges.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.455-458
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• 2005

The Steel-Confined Prestressed Concrete Girder(SCP Girder) has been developed, which maximizes structural advantages of components (concrete, steel plate and tendon) and can be used to construct the middle or long span bridge with low-height girder. And recently, a continuous beam type of SCP Girder has been being developed to decrease size and self weight of girder in comparison with a simply-supported type. In this study, as part of developing the continuous beam type of SCP Girder, a new type of anchorage zone is proposed in order to address tendons effectively and decrease section size of SCP Girder efficiently. And also, the experimental test was carried out using a real scale specimen to examine the behavior of proposed anchorage zone.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.283-289
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• 1996

In this paper, the mix design of the super flowing concrete is described with respcet to basic concept, confined water ratio($\beta_p$), volume ratio of water-binder(w/b), volume ratio of fine aggregates($S_r$) and coarse aggregates($G_v$). The primary purposes of this study are to evaluate the effects of cementitious materials(fly ash, slag cement, portland cement), mixing factors ($\beta_p$, w/b, $S_r$, $G_v$)., and to propose the mix design method of the super flowing concrete. As results of this study, confined water ratio($\beta_p$) of cementitious materials is very high (0.99~1.1), and then the ranges of the optimum mixing factors to be satisfied with the super flowing concrete are $S_r$ 47$\ell$ 2%, $G_v$ 52$\ell$ 1%.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2804-2809
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• 2008

Experimental results and numerical computations were conducted to investigate the effect of the confined wall on the flow and heat transfer characteristics for a two-dimensional impinging jet. Experimental results and Numerical solutions were obtained by using the particle image velocimetry and the commercial CFD code (CFX 11), respectively. The parameters studied were jet Reynolds number (Re=5,000), conditions of confined wall (unventilate), nozzle to plate spacings ($H/W=1{\sim}16$), and nozzle to nozzle spacing (S/W=6). Experimental and numerical results were agreed well with each other. The maximum heat transfer point was found variation of nozzle to plate spacings.

• Bulletin of the Korean Chemical Society
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• v.30 no.4
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• pp.810-816
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• 2009

The interactions between four Keggin-type POMs (${SiW_{12}O_{40}}^{4-},\;{PW_{12}O_{40}}^{3-},\;{SiMo_{12}O_{40}}^{4-},\;and\;{PMo_{12}O_{40}}^{3-}$) and glassy carbon (GC) and highly oriented pyrolytic graphite (HOPG) surfaces are investigated in a systematic way. Electrochemical results show that molibdate series POMs adsorb relatively stronger than tungstate POMs on GC and HOPG surfaces. Adsorption of POMs on HOPG electrode surfaces is relatively stronger than on GC surfaces. ${SiMo_{12}O_{40}}^{4-}$ species exhibits unique adsorption behaviors on HOPG surfaces. Surface-confined ${SiMo_{12}O_{40}}^{4-}$ species on HOPG surfaces exhibit unique adsorption behaviors and inhibit the electron transfer from the solution phase species. The catalytic activity of the surface-confined POMs for hydrogen peroxide electroreduction is also examined, where ${PW_{12}O_{40}}^{3-}$ species adsorbed on GC surfaces exhibits the highest catalytic efficiency among the investigated POM modified electrode systems.