• Macromolecular Research
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• 제15권1호
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• pp.74-81
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• 2007

A series of photoreactive mesogens based on chalcone were prepared and their morphological behavior and reactivity were studied according to a variable number of alkyloxy tail carbons. The linear ester compounds 3a-h comprised two chalcone units connected to a benzene ring through ester linkages. All linear ester compounds showed enantiotropic liquid crystalline phases. The X-ray diffractograms for the mesophases of compounds 3a-h showed a set of reflections in the small-angle region which consisted of more than three sharp diffraction peaks with d spacings in the ratio of 1:1/2:1/3, confirming the well defined smectic A structures of the compounds. Compounds 3a-h were considered to be bifunctional monomers due to the presence of two photoreactive chalcone groups. Upon UV irradiation, its polymerization proceeded through the [2+2] addition reaction between chalcone units in a stepwise manner. An image pattern was obtained by the photopolymerization of the liquid crystal of the compound (3h) with decyloxy tails through a photomask. The irradiated part became dark while the masked part remained birefringent under polarized optical microscopy, which was ascribed to the production via the UV irradiation of a polymer or a dimer having cyclobutane rings by [2+2] addition, which thereby disrupted the alignment of the molecules.

• Bulletin of the Korean Chemical Society
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• 제32권4호
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• pp.1138-1142
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• 2011

Kinetic studies for the reactions of Y-aryl phenyl chlorothiophosphates with X-pyridines have been carried out in acetonitrile at $35.0^{\circ}C$. The Hammett and Bronsted plots for substituent X variations in the nucleophiles are biphasic concave upwards with a break point at X = 3-Ph, while the Hammett plots for substituent Y variations in the substrates are biphasic concave downwards (and partially upwards) with a break point at Y = H. The signs and magnitudes of the cross-interaction constant (${\rho}_{XY}$) are strongly dependent upon the nature of substituents, X and Y. The proposed mechanism is a stepwise process with a rate-limiting step change from bond breaking with the weaker electrophiles to bond formation with the stronger eletrophiles. The nonlinear free energy correlations of biphasic concave upward plots for substituent X variations in the nucleophiles are rationalized by a change in the attacking direction of the nucleophile from a backside with less basic pyridines to a frontside attack with more basic pyridines.

• Environmental Engineering Research
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• 제19권4호
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• pp.395-399
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• 2014

Operation characteristics of the sequencing batch reactor (SBR) process with electro-flotation (EF) as a solid liquid separation method (EF-SBR) were investigated. EF-SBR process showed excellent solid-liquid separation performance which enabled to separate biosolids from liquid phase within 30 min and to extend cyclic reaction time. Although influent organic loading rate was increased stepwise from 5 to 15 g COD/day, food to microorganisms (F/M) ratio could be maintained about 0.3 g COD/g VSS/day in EF-SBR because biomass concentration could be easily controlled at desired level by EF. However, it was impossible to increase biomass concentration at the same level in control SBR (C-SBR) process because solid-liquid separation by gravity settling showed a limitation at higher mixed liquor suspended solids (MLSS) concentration with 60 min of settling time. Total chemical oxygen demand (TCOD) removal efficiency of EF-SBR process was not decreased although influent organic loading rate became 3 times higher than initial value. However, it was seriously deteriorated in C-SBR process after increasing the rate over 10 g COD/day, which was accounted for insufficient organic removal by relatively higher food to microorganisms (F/M) ratio as well as biosolids wash-out by a limitation of gravity sedimentation.

• 간호행정학회지
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• 제22권1호
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• pp.91-98
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• 2016

Purpose: The aim of this study was to identify the relationship between nurses' knowledge of adverse drug reactions (ADR), attitudes, and monitoring practices and to establish an effective ADR reporting system and provide baseline data for its activation. Methods: The participants in this study were chosen by convenience sampling and included 182 nurses working at major general hospitals that operate a Regional Drug Safety Center. Data were collected from June 1 to 12, 2015 and analyzed using Cronbach's ${\alpha}$, descriptive statistics, independent t-test, one way ANOVA, Pearson correlation coefficient and stepwise regression with the SPSS program. Results: The nurses' average score for knowledge was 7.62 points, for attitude, 41.04 points and for monitoring practices, 34.22 points. ADR monitoring practices positively correlated with knowledge (r=.19, p=.011), attitude (r=.41, p<.001), drug performance competency (r=.54, p<.001), and drug education satisfaction (r=.54, p<.001). Drug performance competency, drug education satisfaction, and attitudes explained 42.0% of the ADR monitoring practices (Adj $R^2=.42$, F=43.95, p<.001). Conclusion: In order to facilitate and encourage nurses' voluntary monitoring practice of ADR, efforts must be made to create positive attitudes toward ADR, and to increase drug performance competency and drug education satisfaction.

• Bulletin of the Korean Chemical Society
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• 제34권12호
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• pp.3733-3737
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• 2013

Polyacrylonitrile (PAN)-based ultrafine fibers and carbon fibers were produced by wet-spinning, and the crystal sizes and thermal and mechanical properties of the fibers were investigated. Scanning electron microscopy revealed that the superfine fibrils in the surfaces of the PAN/polyvinyl acetate (PVA) blend fibers increased slightly with increasing PAN content before removal of the PVA. Differential scanning calorimetry indicated that the PAN and PVA in the blend fibers do not mix and, therefore, each maintains their inherent thermal characteristics. The crystal sizes of the blend fibers prepared by removing PVA with water increased at 5 wt % water. The extent of the reaction of the PAN carbon fibers, as calculated from the FT-IR spectra, is maximized at the stepwise temperature of $230^{\circ}C$, and the density increased significantly above this temperature. The carbon fibers had relatively good mechanical properties, as shown by their tensile strength and modulus values of 2396 MPa and 213 GPa, respectively.

• Journal of Information Technology Applications and Management
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• 제21권1호
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• pp.177-184
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• 2014

This research analyzes the effects of factors on the demands for outbound to the countries such as Japan, China, the United States of America, Thailand, Philippines, Hong Kong, Singapore and Australia, the countries preferred by many Koreans. The factors for this research are (1) economic variables such as Korea Composite Stock Price Index (KOSPI), which could have influences on outbound tourism and exchange rate and (2) unpredictable events such as diseases, financial crisis and terrors. Regression analysis was used to identify relationship based on the monthly data from January 2001 to December 2010. The results of the analysis show that both exchange rate and KOSPI have impacts on the demands for outbound travel. In the case of travels to the United States of America and Philippines, Korean tourists usually have particular purposes such as studying, visiting relatives, playing golf or honeymoon, thus they are less influenced by the exchange rate. Moreover, Korean tourists tend not to visit particular locations for some time when shock reaction happens. As the demands for outbound travels are different from country to country accompanied by economic variables and shock variables, differentiated measure to should be considered to come close to the target numbers of tourists by switching as well as creating the demands. For further study we plan to build outbound tourism forecasting models using Artificial Neural Networks.

• Bulletin of the Korean Chemical Society
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• 제32권12호
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• pp.4304-4308
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• 2011

Kinetic studies of the reactions of O,O-dimethyl Z-S-aryl phosphorothioates with X-benzylamines have been carried out in dimethyl sulfoxide at $85.0^{\circ}C$. The Hammett (log $k_2$ vs ${\sigma}_X$) and Br$\ddot{o}$nsted [log $k_2$ vs $pK_a$(X)] plots for substituent X variations in the nucleophiles are discrete with a break region between 4-Me and H, while the Hammett plots (log $k_2$ vs ${\sigma}_Z$) for substituent Z variations in the leaving groups are linear. The sign of the cross-interaction constant (${\rho}_{XZ}$) is positive for both the strongly and weakly basic nucleophiles. Greater magnitude of ${\rho}_{XZ}$ (= 2.54) value is observed with the weakly basic nucleophiles compared to with the strongly basic nucleophiles (${\rho}_{XZ}$ = 0.17). The deuterium kinetic isotope effects ($k_H/k_D$) involving deuterated benzylamines [$XC_6H_4CH_2ND_2$] are primary normal ($k_H/k_D$ > 1). The proposed mechanism is a stepwise with a rate-limiting leaving group expulsion from the intermediate involving a frontside nucleophilic attack with a hydrogen bonded, four-center-type transition state for both the strongly and weakly basic nucleophiles.

• 약학회지
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• 제44권3호
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• pp.213-223
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• 2000

SD-994 was prepared from methanol extract of Artemisia argyi by stepwise purification of solvent partioning and silica gel chromatography. In the course of this purification, fractions obtained at each step were investigated for their cytotoxicities against L1210 cells. Fractions A~G prepared from chloroform fraction showed considerable cytotoxicities raging 40~90% against L1210 cells. Subfractions I~IX obtained from fraction A exhibited various cytotoxicities and subfraction I (SD-994) was found to be the most effective compound. $IC_{50}$ values of SD-994 were measured to be $0.5{\;}{\mu\textrm{g}}/ml and less than $0.05{\;}{\mu\textrm{g}}/ml against L1210 cells and normal lymphocytes, respectively: When SD-994 was added to L1210 cell as cytotoxic agent, significantly increased amount of superoxide ($O_2^-$) and dramatically augmented activities of superoxide dismutase (SOD), specially MnSOD and glutathione peroxidase (GPx) were observed according to the concentration and incubation time. Whereas, in case of normal lymphocytes under the same condition, cytotoxicities were not apparent and the generation of superoxide ($O_2^-$) or the activity changes of SOD and GPx were insignificant. These results together indicate that the cytotoxic action of SD-994 against L1210 cell may be achieved via necrosis and/or apoptosis induced by reaction oxygen species which could not probably be completely abolished even by drastically increased antioxidant enzymes, SOD and GPx activities.

• 한국해양바이오학회지
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• 제1권4호
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• pp.311-316
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• 2006

Enzymatic ethanolysis of fish oil with immobilized lipase was investigated for reducing the free fatty acid contents and enhancing the function of fish oil. Ethanolysis reactions were carried out in erlenmeyer flask (25ml) containing a mixture of squid viscera oil and 99.9% ethanol using 1% (based on w/w squid viscera oil) immobilized lipase. The reaction mixtures were incubated at $50^{\circ}C$ and shaken at 100rpm. Ethanol was added into the mixture by stepwise addition method of Shinmada[9]. Measurement of free fatty acid molar amounts was studied by Acid Value. Tendency of oil variation during transesterification was studied by TLC method. Enzymatic ethanolysis composed diglyceride, monoglyceride and fatty acid ethyl ester with reducing free fatty acid contents. Also, selective ethanolysis by Lipozyme TL-IM and Lipozyme RM-IM mostly did not react at the sn-2 position of squid viscera oil. Lipozyme RM-IM was more suitable enzyme to reduce the free fatty acid contents by ethanolysis than Lipozyme TL-IM. Squid viscera oil was transformed into suitable properties (5 in Acid Value) for functional fish oil production.

• Bulletin of the Korean Chemical Society
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• 제29권3호
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• pp.580-584
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• 2008

Second-order rate constants (kN) have been measured spectrophotometrically for reactions of Y-substituted phenyl benzoates (1a-h) with azide ion (N3) in 80 mol % H2O/20 mol % DMSO at 25.0 0.1 oC. The Brnsted-type plot for the azidolysis exhibits a downward curvature, i.e., the slope (b lg) changes from 0.97 to 0.20 as the basicity of the leaving group decreases. The pKao (defined as the pKa at the center of the Brnsted curvature) is 4.8, which is practically identical to the pKa of the conjugate acid of N3 ion (4.73). Hammett plots correlated with s o and s constants exhibit highly scattered points for the azidolysis. On the contrary, the corresponding Yukawa-Tsuno plot results in an excellent linear correlation with r = 2.45 and r = 0.40, indicating that the leaving group departs in the rate-determining step. The curved Brnsted-type plot has been interpreted as a change in the rate-determining step in a stepwise mechanism. The microscopic rate constants (k1 and k2/k1 ratio) have been calculated for the azidolysis and found to be consistent with the proposed mechanism.