• Bulletin of the Korean Chemical Society
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• v.31 no.7
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• pp.2003-2010
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• 2010

A new class of halobenzyloxy or alkoxy 1,2,4-triazoles and their hydrochlorides were synthesized through cyclization starting from commercially available phenylhydrazine. The structures were characterized by MS, IR and $^1H$ NMR spectra as well as elemental analyses. All the synthesized compounds were screened for their antibacterial activities in vitro against Staphylococcus aureus (ATCC29213), methicillin-resistant Staphylococcus aureus (N315), Bacillus subtilis, Escherichia coli (ATCC25922), Pseudomonas aeruginosa, Shigella dysenteriae, Eberthella typhosa, and antifungal activities against Candida albicans (ATCC76615), Aspergillus fumigatus by broth microdilution assay method. The results of preliminary bioassay indicated that 3-(2,4-difluorobenzyloxy)-1-phenyl-1H-1,2,4-triazole hydrochloride exhibited the best inhibitory activity with an MIC value of 56.25 ${\mu}M$ against P. aeruginosa superior to Chloramphenicol, and showed comparable activity with Chloramphenicol against E. coli (ATCC25922).

• Journal of the Korean Institute of Gas
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• v.10 no.2 s.31
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• pp.55-60
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• 2006

Detailed modeling of PEMFCs has been getting considerable interest for predicting the fuel cell performance and also for use in various systems engineering activities. While CFD-based equipment models provide detailed analyses of the performance, they are very time-consuming to develop and run. The computations become quite complex when such models have to be embedded into the flowsheet-level optimization of fuel cell systems. In this paper, we present results about building and using NN-based reduced order models for quickly and repetitively predicting the flow of reactants in a PEMFC manifold.

• Computers and Concrete
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• v.8 no.6
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• pp.617-629
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• 2011

In this investigation, reservoir sediment and municipal sewage sludge were sintered to form the artificial lightweight aggregates. The sintered aggregates were compared with the commercialized lightweight aggregates to in terms of potential alkali-silica reactivity and chemical stability based on analyses of their physical and chemical properties, leaching of heavy metal, alkali-silica reactivity, crystal phase species and microstructure. Experimental results demonstrated that the degree of sintering of an aggregate affected the chemical resistance more strongly than did its chemical composition. According to ASTM C289-94, all potential alkali-silica reactivity of artificial lightweight aggregates were in the harmless zone, while the potential reactivity of artificial lightweight aggregates made from reservoir sediment and municipal sewage sludge were much lower than those of traditional lightweight aggregates.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.1
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• pp.83-89
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• 1996

Multivariate statistical procedures were used to analyse data on the chemical composition and in vitro digestibility of four varienties of rice straw after treatment with 4% NaOH solution, 4% urea solution or distilled water (control) for 48 hours. For each treatment, stepwise discriminant analysis identified the variables which maximized differences between varieties and the eigenvectors from principal component analysis quantified the contribution of these criterion variables to varietal differences. The overall response of varieties to chemical treatment was demonstrated qualitatively, by cluster analysis, and quantitatively, from the magnitude of the principal component scores. The analysis revealed that the urea and control treatments elicited the same response whereas NaOH had the greatest effect on the poorest straw variety. Similar analyses conducted on the botanical fractions of the varieties showed that the relative response of the inflorescence, stem, leaf blade and leaf sheath fractions was not altered by chemical treatment.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.207-210
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• 2003

The chemical mechanical planarization (CMP) process is a method of planarizing semiconductor wafers with a high degree of success. However, fundamental mechanisms of the process are not fully understood. Several theoretical analyses have been introduced, which are focused on kinematics, von Mises stress distributions and hydrodynamic lubrication aspects. This paper is concerned with hydrodynamic lubrication theory as the chemical mechanical planarization model; the three-dimensional Reynolds equation is applied to predict slurry film thickness and pressure distributions between the pad and the wafer. This paper classifies geometry of wafer into 3 types and focuses on the differences between them.

• Tribology and Lubricants
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• v.15 no.1
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• pp.90-97
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• 1999

Chemical-Mechanical Polishing (CMP) refers to a material removal process done by rubbing a work piece against a polishing pad under load in the presence of chemically active, abrasive containing slurry. CU process is a combination of chemical dissolution and mechanical action. The mechanical action of CMP involves tribology. The liquid slurry is trapped between the wafer (work piece) and pad (tooling) forming a lubricating film. For the first step to understand material removal rate of the CMP process, the lubricational analyses were done with commercial 100mm diameter silicon wafers to get nominal clearance of the slurry film, roll and pitch angle at the steady state. For this purpose, we calculate slurry pressure, resultant forces and moments at the steady state in the range of typical industrial polishing conditions.

• Journal of the Mineralogical Society of Korea
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• v.9 no.2
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• pp.82-92
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• 1996

The coarse-grained (0.05∼0.2mm) zeolites occur as the single-crystal cement in the sandstones of the Chunbuk Formation in the Pohang area. The zeolite cements unusually consist of the composite phases of heulandite and clinoptilolite and in a crystal. The zeolite crystals show chemical zoning ranging from 3.56 to 4.10 in Si/(Al+Fe), and tend to become continuously more silicic and alkalic from the margin toward inside of the crystal. The DTA and high-temperature XRD analyses also show complex patterns of both zeolites. Such a composite crystal showing chemical zoning and complex thermo-chemical behaviors indicates that heulandite and clinoptilolite are constituting a solid solution resulted from the coupled substitution of K+Si4+=Ca2+Al3+.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3183-3189
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• 2010

In order to increase the specific capacitance and energy density of supercapacitors, non-aqueous supercapacitors were prepared using lithium transition-metal oxides and activated carbons as active materials. The electrochemical properties were analyzed in terms of the content of lithium transition-metal oxides. The results of cyclic voltammetry and AC-impedance analyses showed that the pseudocapacitance may stem from the synergistic contributions of capacitive and faradic effects; the former is due to the electric double layer which is prepared in the interface of activated carbon and organic electrolyte, and the latter is due to the intercalation of lithium ($Li^+$) ions. The specific capacitance and energy density of a supercapacitor improved as the lithium transition-metal oxides content increased, showing 60% increase compared to those of supercapacitor using a pure activated carbon positive electrode.

• Journal of the Korean Chemical Society
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• v.57 no.3
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• pp.370-376
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• 2013

A back propagation artificial neural network model with one hidden layer is established to correlate the liquid-liquid equilibrium data of hydrocarbon-water systems. The model has four inputs and two outputs. The network is systematically trained with 48 data points in the range of 283.15 to 405.37K. Statistical analyses show that the optimised neural network model can yield excellent agreement with experimental data(the average absolute deviations equal to 0.037% and 0.0012% for the correlated mole fractions of hydrocarbon in two coexisting liquid phases respectively). The comparison in terms of average absolute deviation between the correlated mole fractions for each binary system and literature results indicates that the artificial neural network model gives far better results. This study also shows that artificial neural network model could be developed for the phase equilibria for a family of hydrocarbon-water binaries.

• Korean Journal of Materials Research
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• v.7 no.6
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• pp.472-478
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• 1997

TMS(tetramethysilane, Si(CH$_{3}$)$_{4}$)를 이용하여 RTCVD(rapid thermal chemical vapor deposition)장치에서 Si(111) 기판 위에 $\beta$-SiC(111)를 성장시켰다. 실험변수로는 반응온도, TMS유량, 반응시간, H$_{2}$유량을 변화시켰으며, XRD, IR, SEM, RBS, TEM등을 이용하여 성장된 박막을 분석하였다. 성장된 박막은 crystallized Si, C또한 Si-H, C-H결합은 관찰할 수 없었으나 다결정이었다. TMS의 유량이 증가함에 따라, 성장온도가 감소함에 따라서 미려한 박막을 성장시킬 수 있었으며, 반응의 활성화에너지는 20kcal/molㆍK이었다.