• Membrane and Water Treatment
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• v.7 no.6
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• pp.539-553
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• 2016

As a novel hydrophobic monomer, polytetrahydrofuran diacrylate (PTMGDA) was synthesized by the esterification reaction between polyethylene tetrahydrofuran (PTMG) and acryloyl chloride (AC). In situ free radical polymerization reaction method was utilized to fabricate poly (vinylidene fluoride) (PVDF)-PTMGDA-poly(ethylene oxide) dimethacrylate (PEGMA) ulrafiltration (UF) membranes. The performances of PVDF-PTMGDA-PEGMA UF membranes in terms of morphologies, mechanical properties, separation properties and hydrophilicities were investigated. The introduction of the PTMGDA-PEGMA dopants not only increased the membranes' pure water flux, but also improved their mechanical properties and the dynamic contact angles. The addition of the PTMGDA/PEGMA dopants led to the formation of the finger-like structure in the membrane bulk. With the increase concentration of PTMGDA/PEGMA dopants, the porosity and the mean effective pore size increased. Those performances were coincide with the physicochemical properties of the casting solutions.

• Carbon letters
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• v.5 no.3
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• pp.108-112
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• 2004

Effect of silicon infiltration on the bend and tensile strength of 2D cross-ply carbon-carbon composites are studied. It is observed that bend strength higher than tensile strength in both types of composite is due to the different mode of fracture and loading direction. After silicon infiltrations bend and tensile strength suddenly decreases of carbon-carbon composites. This is due to the fact that, after silicon infiltration, silicon in the immediate vicinity of carbon forms the strong bond between carbon and silicon by formation silicon carbide and un-reacted silicon as free silicon. Therefore, these composites consist of three components carbon, silicon carbide and silicon. Due to mismatch between these three components secondary cracks developed and these cracks propagate from $90^{\circ}$ oriented plies to $0^{\circ}$ oriented plies by damaging the fibers (i.e., in-situ fiber damages). Hence, secondary cracks and in-situ fiber damages are responsible for degradation of mechanical properties of carbon-carbon composites after silicon infiltration which is revealed by microstructure investigation study by scanning electron microscope.

• The Journal of Engineering Geology
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• v.27 no.3
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• pp.323-330
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• 2017

For the formation identification, surface geological survey, drill core analysis, core description and well log analysis are widely used. Among them well log analysis is a popular method with drill core analysis, since it measures continuously physical properties at in-situ. In this study we calculated Thomsen anisotropic parameters (${\varepsilon},\;{\delta},\;{\eta}$) after applying Backus averaging method to the P wave velocity, S wave velocity, and density logs. The well log data application of Blackfoot, Canada, shows the formation could be divided by 12 layers. This shows that Thomsen anisotropic parameters for identifying formation using anisotropic parameters is useful if there is no natural gamma log that is widely used for the formation identification.

• Journal of the Korean Vacuum Society
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• v.7 no.3
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• pp.176-186
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• 1998

Pure Pt, Co and their alloy thin films with three different compositions (Pt66-Co34, Pt40-Co60 and Pt18-Co82) were deposited on Si(100) wafers and proposed as a set of certified reference materials (CRM) for the quantification and standardization of surface compositional analysis. The compositions of the binary alloy thin films were controlled by in-situ XPS analyses and the certified compositions of the films have been determined by ICP-AES and RBS analyses after thin film growth. Through comparison of the compositions determined by in-situ XPS with those by ICP, relatively accurate compositions could be obtained with a matrix effect correction. Standard deviations of XPS and AES round robin tests with the Pt-Co alloy thin films were large up to about 4%. On the other hand, the average compositions of the Pt-Co alloy thin films by two methods were in a good agreement within 1%. The formation of a Pt rich surface layer by ion beam sputtering indicates that the surface modification by preferential sputtering must be understood for a better compositional analysis.

• Advances in nano research
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• v.12 no.3
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• pp.291-300
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• 2022

The behavior of hydrogen species on the surface of the catalyst during the Lewis acid transformation to form Brønsted acid sites over the spherical silica-supported WO_x catalyst was investigated. To understand the structure-activity relationship of Lewis acid transformation and hydrogen bonding interactions, we explore the potential of using the in situ diffuse reflection infrared Fourier transform spectroscopy (DRIFTS) with adsorbed ammonia and hydrogen exposure. From the results of in situ DRIFTS measurements, Lewis acid sites on surface catalysts were transformed into new Brønsted acid sites upon hydrogen exposure. The adsorbed NH₃ on Lewis acid sites migrated to Brønsted acid sites forming NH⁴⁺. The results show that the dissociated H atoms present on the catalyst surface formed new Si-OH hydroxyl species - the new Brønsted acid site. Besides, the isolated Si-O-W species is the key towards H-bond and Si-OH formation. Additionally, the H atoms adsorbed surrounding the Si-O-W species of mono-oxo O=WO₄ and di-oxo (O=)₂WO₂ species, where the Si-O-W species are the main species presented on the Inc-SSP catalysts than that of the IWI-SSP catalysts.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.12-13
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• 2012

An environmentally friendly method for in situ growth of Mg-Al hydrotalcite (HT) film on AZ31 magnesium alloy has been developed. The growth processes and corrosion resistance of the HT film were investigated. Then the HT film was surface modified by phytic acid solution to further improve the corrosion resistance. The film formation involves the dissolution of AZ31 substrate, adsorption of the ions from solution, nucleation of the precursor, followed by the dissolution of $Al^{3+}$, exchanging of $OH^-$ by $CO{_3}^{2-}$ and growth of the HT film. The HT film is very compact and acts as a barrier against $Cl^-$ attack in the early stage of corrosion, and then the surface of the film is dissolved gradually. This dense HT film can provide effective protection to the AZ31 alloy. The HT film with surface modification by phytic acid presents a self-healing feature and exhibits better corrosion resistance.

• Tunnel and Underground Space
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• v.26 no.4
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• pp.304-315
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• 2016

In this study, the current horizontal stress characteristics of the Tertiary rock formations in the Pohang Basin are investigated on the basis of the in-situ rock stress measurements at depths from 75 m to 716 m of the 3 test boreholes in the Doumsan area, Pohang. The deep hydraulic fracturing stress measurement results indicated that the horizontal stress components in the test site appear far lower than the average ones by the linear fit for the data set measured from the other domestic sites. But, borehole scanning revealed clearly that lots of small and large scale borehole failures occurred due to the low strength characteristics of the existing rocks. To obtain more accurate and overall information on the horizontal stress direction, the integrated analysis combining the hydraulic fracturing stress measurement and borehole scanning data set were additionally carried out. The analysis results showed that in the upper sedimentary and the lower volcanic rock formation, the dominant orientations of the current maximum horizontal stress components were appeared in the range of $80^{\circ}{\sim}100^{\circ}$ (N80E~N80W) and $120^{\circ}{\sim}140^{\circ}$ (N60W~N40W), respectively. From this study result it was found that the maximum horizontal stress directions have a tendency to rotate in a clockwise direction as the rock formation changes with depth in the test site.

• Economic and Environmental Geology
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• v.42 no.5
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• pp.435-444
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• 2009

In situ stabilization of heavy metals through adsorption onto indigenous bacterial biofilm developed on soil particles was investigated. Biofilms were developed in soil columns by supply of various carbon sources such as acetate, lactate and glucose. During development of biofilms, acetate, lactate, and glucose solutions were flew out from the soil columns with volume ratios of 98.5%, 97.3%, and 94.7%, respectively, when compared with soil column supplied with deionized water. Decrease in effluent amounts through the soil columns amended with carbon sources over time indicated the formation of biofilms resulting in decrease of soil porosity. Solutions of Cd, Cr(VI), Cu, Pb, and Zn were injected into the biofilms supported on soil particles in the columns, and the dissolved heavy metals in effluents were determined. Concentrations of dissolved Cd, Cr(VI), Cu, and Zn in the effluents through biofilm columns were lower than those of control column supplied with deionized water. The result was likely due to enhanced adsorption of the metals onto biofilms. Efficiency of metal removal by biofilms depended on the type of carbon sources supplied. The enhanced removal of dissolved heavy metals by bacterial biofilms in this study may be effectively applied to technical development of in situ stabilization of heavy metals in natural soil formation contaminated with heavy metals.

• The Journal of Engineering Geology
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• v.10 no.3
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• pp.225-236
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• 2000

We conducted laboratory simulations of deep vertical drilling into the earth's crust to induce borehole breakouts and investigated their potential use for estimating in situ stress magnitudes in Westerly granite and Berea sandstone. Our experiments consisted of two major stages, a series of triaxial tests and borehole-breakout formation tests under a wide range of far-field stresses. We derived the Mohr-Coulomb, Nadai and Mogi failure criteria from the triaxial test results. Each criterion was compared with the stress condition at breakout boundaries. We concluded that the well known Mohr-Coulomb criterion is not compatible with the stress condition at breakout failure. On the other hand, polyaxial (truly triaxial) failure criteria such as the Nadai criterion for Berea sandstone and the Mogi criterion for Westerly granite were much more suitable for predicting breakout failure zone. Such failure criteria appeared to enable the reliable estimation of the magnitude of one of two horizontal principal stresses if the other one is known.

• Korean Chemical Engineering Research
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• v.49 no.5
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• pp.669-675
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• 2011

Fourier Transform Infrared Spectroscopy and in-situ Position Annihilation Lifetime Spectroscopy(PALS) analysis of hybrid film, which consist of silsesquioxane(SSQ) and 4-tert-butyl calix[4]arene-O,O',O",O'"-tetraacetic acid tetraethyl ester(CA[4]) have been investigated in order to understand initial formation of nanopore in the next generation porous low-k dielectrics(k < 2.0). SSQ/CA[4] can provide effective homogeneous thin film having porous structure. The porogen decomposition behavior were completely different in the two kinds of SSQ/CA[4] based hybrid film (i.e. SSQ/CA[4] 10 and SSQ/CA[4] 20%). Relatively small pores(1.5 nm) come from dispersion of uni-molecular CA[4] in the SSQ matrix have been generated at $300^{\circ}C$, while mesopores(2.5~3.0 nm) induced from self assembled CA[4] have been generated at $250^{\circ}C$. It might be due to highly interconnected structure of SSQ/CA[4] 20% hybrid thin film resulting in facile evacuating of decomposed fragment of CA[4] molecule.