• Proceedings of the Korea Concrete Institute Conference
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• 1992.04a
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• pp.143-147
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• 1992

Description of the behavior of the R.C structural members fixed on massive concrete is not normally generalization of recognized configuration for regular R.C. design guidanes. This can be due to the complexity of evaluation of internal resistancy and deflection changes of the members subjected to the various external forces. On the base of axially loaded member fixed on footing, however, the estimation of deflection changes due to flexural force shear force and rotational force is to be carried out in ways of specifying the bond characteristics of axial bars embedded in massive concrete. This work is to quantify adhesion of steel-concrete, initial concrete cracking stress near bar rib, maximum bond stress and residual stress in concrete respectively. In addition to quantification of them for particulate behavior, the suggestions of multi-linear bond stress-slip diagram made in carrying out finite element analyses for adhesion failure, examining concrete cracking status and reviewing existing experimental data lead to alternatively constructed relationship between bond stress and slip for a axial bars embedded massive concrete.

• Proceedings of the KACD Conference
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• 2001.11a
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• pp.584.1-584
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• 2001

The purpose of this study was to evaluate the effects of various cavity configuration on bond strength and micro leakage of composite restoration. The specimens were prepared as followed; For control group(C=1), bovine teeth were wet-ground to expose flat dentin surface and in experimental groups, cylindrical cavities, same all2mm deep and 6mm in diameter(C=2.3), 4mm(C=3.0), and 3mm(C=3.7) were prepared.(omitted)

• Proceedings of the KACD Conference
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• 2001.11a
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• pp.576.1-576
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• 2001

The objective of this study was to evaluate the effect of configuration of cavity on the mechanical properties such as flexural strength and elastic modulus of resin composites. The materials used were $Clearfil^{TM}$ AP-X(Kuraray, Japan) and $Esthet-X^{TM}$(Dentsply, USA) as resin composite. Dentin-bonding systems used in the study were $Clearfil^{TM}$ SE Bond(Kuraray, Japan) and Prime ＆ Bond $NT^{TM}$(Dentsply, USA). The specimens were prepared as 6 groups with 2 control groups and 4 experimental groups.(omitted)

• Bulletin of the Korean Chemical Society
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• v.13 no.2
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• pp.173-176
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• 1992

The spectroscopic studies of the 5,7-dimethoxycoumarin(5,7-DMC) and 4,5',8-trimethylpsoralen(TMP) and the conformational stability of 5,7-DMC-thymidine, 4,5',8-TMP-thymine were carried out by the CNDO/S and molecular mechanics calculation. Theoretical transition energies and direction of polarizations calculated by the CNDO/S method have been used for the interpretation of the observed results. The calculated absorption spectra of 5,7-DMC are qualitatively similar to experimental ones with their characteristic visible bands. MM2 force field calculation on the possible $C_4-cyclophotoadducts$ formed between 5,7-DMC and thymidine through a cycloaddition. of $C_3$, $C_4$ bond of 5,6-DMC to $C_5$, $C_6$ bond of thymidine showed the most stable photocycloadduct to have the anti-head to tail configuration. The major photoadduct of 4,5',8-TMP-thymine has the cis-anti configuration.

• Computers and Concrete
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• v.33 no.5
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• pp.519-533
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• 2024

Many materials including cementitious concrete-type materials undergo material property changes during high-rate loading. There is a wealth of research regarding this phenomenon for concrete in compression and tension. However, there is minimal knowledge about how mortar material used in concrete masonry unit (CMU) construction behaves in high-rate shear loading. A series of experiments was conducted to examine the bond strength of mortar bonded to CMU units under high-rate shear loading. A novel experimental setup using a shock tube and dynamic ram were used to load specially constructed shear triplets in a double lap shear configuration with no pre-compression. The Finite Element Method was leveraged in conjunction with data from the experimental investigation to establish if the shear bond between concrete masonry units and mortar exhibits any rate dependency. An increase in shear bond strength was observed when loaded at a high strain rate. This data indicates that the CMU-mortar bond exhibits a rate dependent strength change and illustrates the need for further study of the CMU-mortar interface characteristics at high strain rates.

• Smart Structures and Systems
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• v.3 no.1
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• pp.1-22
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• 2007

The energy efficiency of a self-powered wireless sensing system for pressure monitoring in injection molding is analyzed using Bond graph models. The sensing system, located within the mold cavity, consists of an energy converter, an energy modulator, and a ultrasonic signal transmitter. Pressure variation in the mold cavity is extracted by the energy converter and transmitted through the mold steel to a signal receiver located outside of the mold, in the form of ultrasound pulse trains. Through Bond graph models, the energy efficiency of the sensing system is characterized as a function of the configuration of a piezoceramic stack within the energy converter, the pulsing cycle of the energy modulator, and the thicknesses of the various layers that make up the ultrasonic signal transmitter. The obtained energy models are subsequently utilized to identify the minimum level of signal intensity required to ensure successful detection of the ultrasound pulse trains by the signal receiver. The Bond graph models established have shown to be useful in optimizing the design of the various constituent components within the sensing system to achieve high energy conversion efficiency under a compact size, which are critical to successful embedment within the mold structure.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.129-129
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• 2012

Covalently bonded halogen ligands possess unusual charge distributions, attracting both electrophilic and nucleophilic molecular ligands to form halogen bonds. In many biochemical systems, halogen bonds coexist with hydrogen bonds, being complementary to them due to their similar bond strength and dissimilardirectionality. In this study, we directly visualize the individual molecular configuration of chlorinated 1,5-dichloroanthraquinone and brominated 1,5-dibromoanthraquinone molecules on Au(111) using scanning tunneling microscopy. The precise arrangements of observed molecular structures were explained in the context of halogen and hydrogen bonds. We discuss the distances and the strengths of the observed halogen and hydrogen bonds, which are consistent with previous bulk data.

• Bulletin of the Korean Chemical Society
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• v.14 no.6
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• pp.740-743
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• 1993

By considering both electron-electron and electron-lattice interactions, the effect of charge transfer on the bond structure and electronic states of $C_{60}$ is studied without configuration limitation. The results show that the electron-electron interaction does not eliminate the layer structure of the bond distortion and the self-trapping of transferred electrons. For charged ${C_{60}}^{2-}$, there exist two localized electronic states, which possess laminar wave functions, and four nonequivalent groups of carbon atoms, which induce a fine-structure in the NMR spectrum line.

• Nuclear Engineering and Technology
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• v.9 no.1
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• pp.39-44
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• 1977

The configuratior and conformation of N-methyl-C-phenylalkyl-ketimine isomers, Ph-CR=N$CH_3$ (R=H, $CH_3$, $CH_3$CH$_2$), have been studied from extended Huckel molecular orbital calculations. The result shows that the E-configuration of the C=N double bond is favored compared with that of the Z-configuration. The most preferable conformation of the phenyl ring rotamer in N-methyl-C-phenylaldimine and N-methyl-C-phenylmethylketimine are the coplanar forms with regard to the C=N plane, but the conformation of the $CH_3$CH$_2$-rotamer, in N-methyl-C-phenylethyl-ketimine, the gauche form (dihedral angle between C=N and $CH_3$CH$_2$- plane=90$^{\circ}$) is favored.

• Magazine of the Korea Concrete Institute
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• v.8 no.3
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• pp.147-155
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• 1996

In this study a model for the constitutive relation of a plane concrete is proposed using a micromechariical model. In this model a precursor crack is assumed to exist in the aggregate-cement paste interface, and the LEFM is used to predict the nucleation of the bond cracks and the grow th of mortar cracks. For computational convenience the bond crack-mortar crack configuration is transformed into a straight crack with a point force in the middle. 'The overall compliance and the cons,titutive relation are predicted from the damage due to microcracks, and the predicted stress-strain curves are compared with some experimental data. According to the results, the model predictions are better for under tensile loading than under compression, for high, strength concrete than for normal strength concrete.