• Carbon letters
• /
• v.19
• /
• pp.40-46
• /
• 2016

Nitrogen-atom doped graphene oxide was considered to prevent the dissolution of polysulfide and to guarantee the enhanced redox reaction of sulfur for good cycle performance of lithium sulfur cells. In this study, we used urea as a nitrogen source due to its low cost and easy preparation. To find the optimum urea content, we tested three different ratios of urea to graphene oxide. The morphology of the composites was examined by field emission scanning electron microscope. Functional groups and bonding characterization were measured by X-ray photoelectron spectroscopy. Electrochemical properties were characterized by cyclic voltammetry in an organic electrolyte solution. Compared with thermally reduced graphene/sulfur (S) composite, nitrogen-doped graphene/S composites showed higher electroactivity and more stable capacity retention.

• The Korean Journal of Ecology
• /
• v.20 no.1
• /
• pp.15-25
• /
• 1997

The deciduous shrubs, Lindera sericea belonging to family Lauracea are distributed in Mt. Chogye and Mudeung locally. To estimate the community structure of this shrub, the relationship between the floristic composition and environmental factors of 20 sites in Mt. Chogye were investigated. L. sericea community distributed at the hum양 zone of altitude 305-480 m in ES and NE slope of $15~30^{\circ}$. The floristic composition of this communities consisted of 17-32 species varied with sites. Sasa borealis, Sapium japonicum, and Quercus serrata were the constant species over 90%. The forest vegetation was classified as Sasa borealis-Lindera sericea community, and the Sasa borealis-Meliosma oldhamii, and Sasa borealis-Callicarpa japonica were as subunit community. Acidity, organic matter content, inorganic phophate, potassium, calcium, magnesium, cation exchange capacity and conductivity were determined as environmental factors. Diameter of stem at ground surface and stem, distribution area and growth property of this plant were investigated, and this plant was presumed to be a relic endemic species.

• Textile Coloration and Finishing
• /
• v.21 no.3
• /
• pp.19-25
• /
• 2009

Polymerization of tetraethoxysilane on a glass substrate was investigated by remote microwave plasma using argon with portions of nitrous oxide as carrier gas. Transparent layer like a thickness of 0.5 ${\mu}m$ 3 ${\mu}m$ were obtained, differing in chemical composition, depending on plasma power and treatment time as well as on ageing time. In general the milder the treatment and the shorter the ageing was, the higher was the content of organic structural elements in the layer. We have identified that the chemical structure of our samples composed of mainly Si O and Si C groups containing aliphatics, carbonyl groups. These results were obtained by X ray photon spectroscopy, Fourier transformed infrared spectroscopy, and scanning electron microscope combined with Energy dispersive X ray spectroscopy.

• Food Science and Biotechnology
• /
• v.16 no.3
• /
• pp.374-380
• /
• 2007

Chemical and sensory profiles of 5 Korean commercial rice wines (yakju) were developed using descriptive, physicochemical, and volatile analyses. Color, 6 aroma, and 5 taste attributes of these rice wines were evaluated by a panel of 13 judges. Sample wines were analyzed for titratable acidity, ethanol content, pH, Hunter colorimeter value, organic acids, and free sugars. Volatile analysis of the samples revealed the presence of 2 acids, 7 alcohols, 19 esters, and 5 miscellaneous compounds. Based on principal component analysis of the descriptive data, rice wines were primarily separated along the first principal component, which accounted for 57% of the total variance between the rice wines with high intensities of 'color' and 'sweet aroma' versus 'ginseng' aroma.

• Korean Journal of Veterinary Research
• /
• v.32 no.3
• /
• pp.413-419
• /
• 1992

Deoxynivalenol producing isolates of Fusarium Graminearum R 6576 was grown on rice for 25 days at 19,25 and $28^{\circ}C$. Maximum production of deoxynivalenol(DON) by Fusarium graminearum R 6575 occurred at $28^{\circ}C$ and 20 days. Maximum concentration of 940 ppm DON were obtained after 20 days at an initial moisture content of 40%. A DON derivative, 15-acetyl-DON (15-ADON), was also found at concentrations of 150~300ppm after 5~10 days. Crude culture extracts were purified by water-saturated silica gel column chromatography which selectivity extracted DON when methylene chloride was as the mobile phase. Purity of crystallized DON was verified by thin layer and high performance liquid chromatography. Also this method was advantage method or production of DON and require little organic sorbent than the other methods.

• Korean Journal of Veterinary Research
• /
• v.50 no.4
• /
• pp.259-264
• /
• 2010

Melamine is an organic base and a trimer of cyanamide which contains 66% nitrogen by mass, but it was sometimes illegally added to food products in order to enhance the apparent protein content for the bigger profit. Many Chinese infants and pet animals fed melamine-containing formulas suffered acute kidney failure with renal crystal formation. Fish feeds were also recently found to be contaminated with melamine. This experiment has been designed to determine whether renal crystals can be experimentally induced in crucian carp (Carassius carassius) fed melamine and cyanuric acid (each at 400 mg/kg/day for 3 days) in combination, and to compare experimentally induced crystals with those from pet animals with triazine related renal failure. The results showed that all fish developed gold brown renal crystals arranged in radial spherulites in the renal tubules, similar to those detected in the pet animals.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.33 no.2
• /
• pp.1-7
• /
• 2001

Use of high yield pulp and recycled fiber as raw materials and water system closure result in higher fines content and buildup of organic and inorganic contaminants in white water. These are detrimental for the effectiveness of chemical additives including retention aids. Thus it is imperative to employ a retention systems that maintains its efficiency in closed papermaking system for reducing fresh water consumption. The performance of four different microparticle retention systems including cationic polyacrylamide (C-PAM)/bentonite, highly charged cationic starch (HCS)/silica, C-PAM/micropolymer, cationic guar gum (CGG)/silica was evaluated and compared at three different levels of papermaking system closure. Buildup of detrimental substances in a closed white water system increased cationic demand and finally reduced the performance of retention systems. Cationic starch and guar gums maintained their effectiveness in retention in closed white water systems contaminated with anionic trashes because of their structural rigidity and hydrogen bonding ability. Particularly, cationic guar gums, due its stiffness of molecular structure, appeared perform better than catinonic starch.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 1998.10a
• /
• pp.388-394
• /
• 1998

In this study, the influence of soil contaminant on the cement solidification treatment was considered. Unconfined compression strength(UCS) test was carried out for solidificated specimen, Setting time was measured for cement slurry that was mixed with leachate and wastewater. It was appeared that treatment effect were affected by the the kind of soil, organic content, component of pore water and its concentration. And UCS of samples which were cured in the leachate were decrease about l/5. Especially for the marine clay, UCS of samples which were cured in leachate during 180 days were smaller than 90 days cured samples in the case of cement mixing ratio 5%, 10%.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
• /
• 2001.06a
• /
• pp.1514-1514
• /
• 2001

In this paper a fast non-destructive analytical method to measure various nutrients in the intact tomato---Near infrared Spectrometry NIRs was introduced Using this method the content of some organic acid, vitamin C, reductive sugar, and solid soluble were determined simultaneously. Screen out four wavelengths at 916nm, 1000nm, 1004nm and 832nm to present optimum four optical terms of d$^2$ log(1/R) with second derivative spectra treating data scanned under these wavelengths. The multiple correlation coefficients between these values and those obtained on chemical analysis were 0.983, 0.990, 0.987, and 0.994, respectively, and the standard errors of prediction (SEP) were 0.007, 0.440, 0.037, and 0.057, respectively. These results indicate that NIRs is comparable to chemical methods in both accuracy and precision and is reliable method for determination of nutrients in intact tomato.

• The Korean Journal of Ecology
• /
• v.15 no.4
• /
• pp.365-375
• /
• 1992

The environmental gradient analyses were applied for the distribution patterns of species populations in mt. moak provincial park in korea. The species populations were sequentially ordered along the environmental gradients such as soil moisture, soil ph, soil organic matter content and elevation and were grouped into seven ecological groups by the two-dimensional analyses of temperature-moisture gradient : zelkova serrata group on mesic-lower parts near the streames and well drained stony slopes, carpinus tschonoskii group on mesic-middle parts, quercus acutissima group on lower parts destroyed by human activities, quercus variabilis group on xeric-middle parts, quercus serrata group on xeric-upper middle parts, quercus mongolica group on xeric-upper parts and pinus densiflora group on xeric-rock ridge lines, hillocks and lower parts interfered by human. Four forest vegetation types, zelkova forest dominated by the c. tschonoskii group on mesic-middle parts, oak forest dominated by the groups of q. acutissima, q. variabilis, q. serrata and q. mongolica on xeric sites and pine forest dominated by the p. densiflora group on dry and poor sites, were separated in mosaic chart by the two-dimensional analysis.