• Korean Chemical Engineering Research
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• v.43 no.4
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• pp.503-510
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• 2005

In this research, composite alumina was prepared to add the various promoters by sol-gel method and examined its thermal stability. After sintering at $1,200^{\circ}C$, the thermal stability resulted in following order, $Si{\fallingdotseq}La$ > Ti > $Ba{\fallingdotseq}Ce$ > Y > $Zr{\fallingdotseq}Mg$, in accordance with adding the promoters. Especially in case of silica-added alumina, a phase transformation temperature to ${\alpha}$-alumina increased about $150^{\circ}C$ and after sintering at $1,200^{\circ}C$, it showed to maintain in ${\gamma}$-form and ${\delta}$-form alumina phase. Also it showed an increase of surface area from $3m^2/g$ to $71m^2/g$ compared with pure ${\alpha}$-alumina. In the case of silicaadded alumina, the characterization change of this alumina particle resulted in a delay of phase transformation because Si-O-Al bond was increased when sintered at high temperature. In case of lanthanum-added alumina, there was a sintering delay phenomenon in inter-particles as $LaAlO_3$ structure existed. The existence of lanthanum structure was confirmed by XRD and XPS analysis. It appeared on the alumina surface as $La_2O_3$ structure when it was sintered under $1,000^{\circ}C$, as the perovskite structure of $LaAlO_3$ at above $1,000^{\circ}C$ and as the magneto-plumbite structure of $LaAl_{11}O_{18}$ at above $1,300^{\circ}C$.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.773-778
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• 2002

The variance characteristics of the calcium carbonate contents along to the concrete cover depth takes the prediction method of remaining service life of concrete. Calcium carbonate contents were measured by the Thermo Gravimetric/Differential Thermal Analysis method at three point, depth of 0.25cm, 0.75cm, 1.25cm from the surface of concrete. This prediction method contain some assumption that the chemical protection conferred on steel is through a passive protective oxide film which forms on steel in an environment at or above a pH of 10.5$^{4)}$ .

• Natural Product Sciences
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• v.17 no.4
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• pp.350-353
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• 2011

A new daucosteryl derivative, verticilloside (1), was isolated from the seeds of Malva verticillata L. (Malvaceae). The structure was determined to be 3-O-[${\beta}$-D-(6'-linoleoyl)glucopyranosyl]-${\beta}$-sitosterol based on spectroscopic analyses ($^1H$ and $^{13}C$-NMR, DEPT, COSY, HMQC, and HMBC) and chemical reactions.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.110-111
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• 2006

Most applications of polymers involve blends and mixtures of components including solvents, surfactants, copolymers, fillers, organic or inorganic functional additives, and various processing aids. These components provide unique properties of polymeric materials even beyond those tailored into the basic chemical structures. In addition, skillful processing extends the properties for even greater applications. The perennial challenge of polymer science is to understand and exploit the structure-processing-property interplay relationship. We are developing and demonstrating combinatorial methods and high throughput analysis as tools to provide this fundamental understanding.

• Journal of Magnetics
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• v.19 no.4
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• pp.323-326
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• 2014

Superparamagnetic maghemite nanoparticles were prepared by chemical co-precipitation, followed by a temperate oxidation stage, and investigated using FE-SEM, XRD, TGA, VSM, and M$\ddot{o}$ssbauer spectroscopy. Through SEM image and XRD analysis, its average particle size was found to be 13.9 nm. While VSM magnetic measurement showed typical superparamagnetic behavior at room temperature, M$\ddot{o}$ssbauer spectroscopic investigation revealed that non-vanishing magnetic hyperfine structure were retained. Cation distribution estimated from M$\ddot{o}$ssbauer spectroscopy confirmed the formation of maghemite nanophase in the sample.

• YAKHAK HOEJI
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• v.7 no.1
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• pp.1-7
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• 1963

This investigation is the studies on the solubility analysis for several pharmaceuticals. The equilibrium reactions leading to complex formation of Caffeine and Nicotinamide with Lidocaine and Saccharin have been studied. The equilibrium constant of each complexes have also been calculated. It is shown that complex formation may lead to an increase in the solubilities of the reactants, and that Nicotinamide has more complexing activity than Caffeine. The influence of chemical structure of each components on interaction is also discussed.

• Journal of Environmental Health Sciences
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• v.17 no.1
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• pp.104-109
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• 1991

Carbamates are generally used as insecticide, thus 8-hydroxy-5-chloroquinolinyl-N-ethylcarbamate was newly synthesized. Its physical properties were determined and chemical structure was identified by means of IR, nmr in addition to elemental analysis. The effect of the compound on rat's ileum, and antibacterial activity against Staphylococcus aureus, Salmonella typhi, E. coli, and Pseudomonas aeruginosa were examined. It was observed that the dosage over 100 $\mu$g/ml of the compound relaxed rat's ileum and the same dosage of the compound inhibited growth of the above strains of bacteria.

• Journal of Nutrition and Health
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• v.19 no.3
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• pp.155-160
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• 1986

This study was conducted to purify and characterize further a potent cholesterol lowering material found in Sogi. The ethanol extract of Sogi was purified with acetone and ethanol, and a white powder was obtained. This material yielded t재 spots on a Silicagel thin layer chromatogram. The major material identified by M.P. measurement, elementary analysis and spectrography was considered to be gyrophoric acid. Beside this, minor components (orsellic and leccanolic acids ) were detected.

• Journal of the Korean Wood Science and Technology
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• v.36 no.4
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• pp.44-51
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• 2008

In this study, the effects of carbonization temperature on the physico-chemical properties of Korean red-pine wood (Pinus densiflora S. et Z.) powder charcoal are studied by elemental analysis, nitrogen adsorption-desorption and SEM techniques. The surface structure and physico-chemical properties of the wood charcoal greatly depend on the carbonization temperature and their temperature dependences for sapwood (swd) and heartwood (hwd) are qualitatively analogous. Because of the differences in characteristics such as hardness and composition between heartwood and sapwood, charcoals from heartwood have larger specific surface area and smaller average pore diameter than that from sapwood. Because the decomposition reaction mostly proceeds in the precarbonization stage, the charcoal produced in this stage mainly consists of carbon. The second carbonization reaction is insignificant but still proceeds up to $700^{\circ}C$, and the specific surface area continuously increases. Above $800^{\circ}C$, the surface area is reduced by the pore-filling and narrowing effects and especially above $900^{\circ}C$, new carbon phase with hexagonal column rooted into the pore is formed. The nitrogen adsorption-desorption isotherm of the charcoal is classified as type I and its hysteresis loop was as type H4.

• Structural Engineering and Mechanics
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• v.37 no.5
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• pp.459-473
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• 2011

The study of the early age concrete properties is becoming more important, as the thermal effects and the shrinkage, even in the first hours, could generate cracks, increasing the permeability of the structure and being able to induce problems of durability and functionality in the same ones. The detailed study of the stresses development during the construction process can be decisive to keep low the cracking levels. In this work a computational model, based on the finite element method, was implemented to simulate the early age concrete behavior and, specially, the evaluation of the cracking risk. The finite element analysis encloses the computational modeling of the following phenomena: chemical, thermal, moisture diffusion and mechanical which occur at the first days after the concrete cast. The developed software results were compared with experimental values found in the literature, demonstrating an excellent approach for all the implemented analysis.