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최성신,손채은 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.1
Testing method for the on-site detection of explosive materials contaminated on the travel luggage bag (TLB) and backpack (BP) surfaces was established using ion mobility spectrometry (IMS) and smear matrix. Trinitrotoluene and 1,3,5-trinitro-1,3,5-triazacyclohexane were used as model explosive materials. Two sampling methods of rolling (with a metal roller) and handrubbing were used, and stainless steel mesh was used as the smear matrix for collection of explosive material. Testing parts of the TLB and BP were selected in consideration of contaminant accumulation, physical contact, and sample collection. Explosive materials deposited on polytetrafluoroethylene (PTFE) sheet were transferred to the testing part, the explosive materials existing on the testing part were collected using the smear matrix, and then the collected explosive materials were analyzed using IMS. High signal-to-noise ratio over 10 was applied for the determination of the minimum initial explosive concentration (Cmin_PTFE) to detect in IMS. The hand-rubbing method was much more efficient than the rolling method. The Cmin_PTFE values were different according to the testing parts. The Cmin_PTFE values of the TLB were higher than those of the BP. The experimental results were explained by difference in surface morphology of the testing areas. The testing method can be helpful to select the sampling parts and to collect the explosive materials for on-site security checks.
Chlorine Effect on Thermal Aging Behaviors of BR and CR Composites
최성신,Jong-Chul Kim 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.9
Chloroprene is a chlorine substituent of 1,3-butadiene. Butadiene rubber (BR) and chloroprene rubber (CR) composites were thermally aged at 60, 70, 80, and 90 oC for 2 - 185 days in a convection oven and changes of the crosslink densities by the accelerated thermal aging were investigated. The crosslink densities increased as the aging time elapsed and as the aging temperature became higher. Degrees of the crosslink density changes of the BR composite were on the whole larger than those of the CR one except the short-term thermal aging at 60 and 70 oC. The crosslink densities abnormally increased after themal aging at high temperatures for a long time. Activation energies for the crosslink density changes of the rubber composites tended to increase with increase of the aging time and the variation showed a local minimum. The activation energies of the CR composite were lower than those of the BR one. The experimental results were explained with a role of ligand of chlorine atom of CR in a zinc complex, steric hindrance by chlorine atom of CR, and oxidation of rubber chain.
최성신,Ji-Eun Ko 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.11
Direct methylation behaviors of 20 amino acids with tetramethylammonium hydroxide (TMAH) were studied under diluted conditions with silica. Amino acid concentration was controlled by dilution with silica (SiO2) and the molar ratios of amino acid/silica were 0.20, 0.50, and 2.0. The molar ratios of amino acid/TMAH (0.51 - 4.64) also varied. It was found that arginine, asparagine, aspartic acid, cysteine, glutamic acid, and glutamine did not generate any directly methylated pyrolysis products, whereas alanine, glycine, isoleucine, leucine, methionine, phenylanaline, valine, and proline generated all the directly methylated pyrolysis products. Tri- and tetra methylated products of lysine consisted of two types. Histidine and threonine hardly generated the partly methylated products. Mono- and dimethylated products of serine, tryptophan, and tyrosine were not observed. Relative intensities of the methylated products varied with the amino acid concentration, TMAH concentration, and pyrolysis temperature. Direct methylation behaviors of amino acids were explained by the structural characteristics of amino acids.