• Fisheries and Aquatic Sciences
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• v.13 no.1
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• pp.36-48
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• 2010

An agar-degrading Agarivorans sp. AG17 strain was isolated from the red seaweed Grateloupia filicina collected from Jeju Island. A beta-agarase gene from Agarivorans sp. AG17 was cloned and designated as agrA. agrA has a 2,985 bp coding region encoding 995 amino acids and was classified into the glycoside hydrolase family (GHF)-50. Predicted molecular mass of the mature protein was 105 kDa. His-tagged agrA was overexpressed in Escherichia coli and purified as a fusion protein. The enzyme showed 158.8 unit/mg specific activity (optimum temperature at $65^{\circ}C$ and pH 5.5 in acetate buffer) with unique biochemical properties (high thermal and pH stabilities). Enzyme produced neoagarohexaose, neoagarotetraose and neoagarobiose by degrading agar, and hydrolyzed neoagaro-oligosaccharides were biologically active. Hence the purified enzyme has potential for use in industrial applications such as the development of cosmetics and pharmaceuticals.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1627-1629
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• 1999

In order to analysis the degradation process of epoxy/glass fiber for outdoor condition, FRP laminate was exposed to high temperature and water. Then the degradation process was evaluated by comparing contact angle, surface potential decay, and surface resistivity. For the change of wettability, the contact angle of thermal-treated specimen with the high temperature of $200^{\circ}C$ increased. But that of water-treated specimen decreased. The characteristic of surface potential decay shows the tendency of the remarkable decrease on water-treated specimens, but no difference on thermal-treated specimen compared with untreated one. Also, for the surface resistivity, it shows the same trend compared with the change of contact angle.

• Bulletin of the Korean Chemical Society
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• v.26 no.5
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• pp.776-780
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• 2005

The kinetic studies of the reactions of $\alpha$-chloroacetanilides $(YC_6H_4NRC(=O)CH_2Cl;\;R=H\;(4)\;and\;CH_3$ (5)) with pyridines have been carried out in dimethyl sulfoxide at 95 ${^{\circ}C}$. The pyridinolysis rates are faster with 4 than with 5 whereas the aminolysis rates with benzylamines are faster with 5 than with 4. The Brønsted ${\beta}_X$ values are in the range from 0.30 to 0.32 and the cross-interaction constants, $\rho_{XY}$, are small negative values; $\rho_{XY}$ = -0.06 and -0.10 for 4 and 5, respectively. Based on these and other results, the pyridinolyses of $\alpha$-chloroacetanilides are proposed to proceed via a stepwise mechanism with rate-limiting addition of the nucleophile to the carbonyl group to form zwitterionic tetrahedral intermediate ($T^{\pm}$) followed by a bridged type transition state to expel the leaving group.

• Bulletin of the Korean Chemical Society
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• v.28 no.10
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• pp.1797-1802
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• 2007

The kinetics and mechanism of the nucleophilic substitution reactions of diphenyl phosphinic (1) and thiophosphinic (2) chlorides with substituted X-pyridines are investigated kinetically in acetonitrile at 35.0 and 55.0 oC, respectively. A concerted mechanism with backside nucleophilic attack is proposed for the pyridinolysis of 1, on the basis of the linear Bronsted plot with the βX value of 0.68. In the case of the pyridinolysis of 2, the Hammett and Bronsted plots are biphasic concave upwards with the break point at 3- phenyl pyridine. These results indicate a change in mechanism from a concerted SN2(P) process with direct backside nucleophilic attack for less basic nucleophiles (X = 3-CN-3-Ph) to a stepwise process with frontside attack for more basic nucleophiles (X = 4-MeO-3-Ph). Apparent secondary inverse kinetic isotope effects with deuterated pyridine (C5D5N), kH/kD < 1, are observed for the pyridinolysis of 1 and 2.

• Bulletin of the Korean Chemical Society
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• v.24 no.8
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• pp.1135-1140
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• 2003

The kinetics and mechanism of the pyridinolysis $(XC_5H_4N)$ of Y-aryl phenyl isothiocyanophosphates (1;$(YC_6H_4O)\;(C_6H_5O)$P(=O)NCS) are investigated in acetonitrile at 55.0 ℃. The Hammett plots for substituent (Y) variations in the substrate (log k₂ vs σY) exhibit a convex upward biphasic type with breaks at Y = H. For electron-donating Y groups the Hammett coefficients, ρY, are positive and cross-interaction constant ρXY is negative, while those for electron-withdrawing Y groups ρY values are negative with a positive ρXY. These results are interpreted to indicate mechanistic change at the breakpoint (σY = 0) from a concerted to a stepwise mechanism with rate-limiting expulsion of the $^-NCS$ group from a trigonal bipyramidal pentacoordinated (TBP-5C) intermediate. Biphasic plots of log k₂ vs σX or $pK_a$(X) with steeper slopes for the more basic nucleophiles are obtained suggesting an equatorial nucleophilic attack in contrast to an apical attack for the less basic nucleophiles with smaller magnitude of ρX or βx.

• Bulletin of the Korean Chemical Society
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• v.23 no.2
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• pp.221-224
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• 2002

Nucleophilic addition reactions of benzylamines (BA; $XC_6H_4CH_2NH_2$) to ethyl-${\alpha}$-cyanocinnamates (ECC;$YC_6H_4CH$=C(CN)COOEt) have been investigated in acetonitrile at $30.0^{\circ}C$. The rate is first order with respect to BA and ECC. The rate is slower than that expected from the additive effect of ${\sigma}^-$ or $R^-$ for the activating groups (CN and COOEt). Natural. bond orbital ${\pi}^{\ast}_{c=c}$ calculations show that the contribution of COOEt group may not be fully effective despite the coplanar molecular structure. The selectivity parameters including the cross-interaction constant (${\rho}_{xy}$ = -0.22) indicate that the addition occurs in a single step. The kinetic isotope effects ($k_H/k_D$=2.5-2.8) involving deuterated BA ($XC_6H_4CH_2ND_2$) nucleophiles and activation parameters (${\Delta}H^{\neq}=4{\sim}6\;kcal\;mol^{-1};{\Delta}S^{\neq}=-45{\sim}-52\;e.u.$) suggest a cyclic transition state in which N-$C_{\alpha}$ and H-$C_{\beta}$ bonds are formed concurrently.

• The Journal of the Korea Contents Association
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• v.6 no.9
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• pp.50-59
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• 2006

This paper proposes an automatic video monitoring system and its application to emergency detection by analyzing human behavior using neural network. The object area is identified by subtracting the statistically constructed background image from the input image. The identified object area then is transformed to the feature vector. Neural network has been adapted for analyzing the human behavior using the feature vector, and is designed to classify the behavior in rather simple numerical calculation. The system proposed in this paper is able to classify the three human behavior: stand, faint, and squat. Experiment results shows that the proposed algorithm is very efficient and useful in detecting the emergency situation.

• 대한예방의학회:학술대회논문집
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• 1999.10a
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• pp.242-243
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• 1999

• The Korean Journal of Nuclear Medicine
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• v.22 no.2
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• pp.187-192
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• 1988

A gamma camera coupled to a computer was used in 20 normal volunteers after ingestion of the mixture of $^{99m}Tc-DTPA$ and milk in order to determine gastric emptyng time (GET) and to evaluate the effect of metoclopramide, a dopamine antagonist that stimulates gastric motility, to gastric emptying. The normal value for biological gastric emptying half time was found to be $63{\pm}7$ minutes, and the gastric emptying was monoexponential fashion, at least for the first 60 minutes. Among the 20 volunteers, nine were repeated the test after injection of metoclopramide, which has significantly reduced the value of GET to $31{\pm}3$ minutes (p<0.01). GET test using $^{99m}Tc-DTPA$ is very useful in gastric function evaluation, especially in follow-up check of the functional change.

• Korean Journal of Pharmacognosy
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• v.32 no.4 s.127
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• pp.292-296
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• 2001

The Radix of Peucedanum japonicum (Umbelliferae) has been used for dispelling wind-damp, headache, chills and wind cold. In order to evaluate to quality of it, the method for the quantitative determination of peujaponiside $(peucedanol\;7-O-{\beta}-D-apiofuranosyl(1{\rightarrow}6)-{\beta}-D-glucopyranoside)$ as standard compound has been developed. Peujaponiside is a major compound of Peucedani Radix. It was analyzed by HPLC using the solvent system of 15% $CH_3CN$. The amount of peujaponiside from Peucedani Radix are in the range 0.14% (n=20).