• Journal of the Korean Chemical Society
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• v.34 no.2
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• pp.184-188
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• 1990

Rates for reactions of substituted phenacyl bromides with imidazole and those of substituted imidazoles with phenacyl bromide were measured by an electric conductivity method. The rates were accelerated by electron-withdrawing substituents of phenacyl bromide and these reactions obeyed well both the linear free energy relationship and the isokinetic relationship. The relation between pKa's of substituted imidazoles and reaction constants fit the Bronsted rule. However, the case of 2-methylimidazole deviated far from this rule exerting steric hindrance. The reaction proceeded much faster in acetonitrile than in methanol and the observed ratio, k2 (acetonitrile)/k2 (methanol), was considerably larger than the value calculated from the Kirkwood equation.

• Journal of the Korean Chemical Society
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• v.20 no.4
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• pp.270-276
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• 1976

The absorption spectra and the dissociation constants of various sulfophthaleins have been measured in the presence of a cationic surfactant. In the presence of 2.0 ${\times}$ 10-3 M zephiramine and an ionic strength of 0.05 at 25${\pm}1^{\circ}C$ the absorption maxima of the basic forms are shifted to red by 6${\sim}$21 nm and their molar absorptivities are increased, while the absorption maxima of the yellow forms are shifted to blue by 4${\sim}$20 nm and their molar absorptivities are decreased. The decreases in pKa values are of the order of ranging -1.38${\sim}$0.37. The characteristic of the observed changes has been explained by the assumption that the dye molecule adsorbed on micellar surface forms a stable coplanar structure easily and then the conjugation in the dye molecule is elevated.

• Bulletin of the Korean Chemical Society
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• v.19 no.7
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• pp.776-779
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• 1998

Second-order rate constants have been measured spectrophotometrically for the addition reaction of a series of alicyclic amines to 3-butyn-2-one to yield their respective enamines at 25.0 'C. The reactivity of the amines increases with increasing the basicity of the amines. However, the Bronsted-type plot obtained exhibits a downward curvature as the basicity of the amines increases, i.e. βnuc decreases from 0.3 for low basic amines (pKa < 9) and to 0.1 for highly basic amines (pKa > 9). Such a curvature in the Bronsted-type plot is clearly indicative of a change in the reaction mechanism or transition state structure. From the corresponding reactions run in D2O, the magnitude of kinetic isotope effect (KIE) has been calculated to be about 0.8 for highly basic amines and 1.21 for weakly basic amines. The difference in the magnitude of KIE also supports a change in the reaction mechanism or transition state structure upon changing the basicity of the amines. Furthermore, the small KIE clearly suggests that H+ transfer is not involved in the rate-determining step, i.e. the addition reaction is considered to proceed via a stepwise mechanism in which the attack of the amines to the acetylene is the rate-determining step. The curvature in the Bronsted-type plot has been attributed to a change in the degree of bond formation between the amine and the acetylene.

• The Korean Journal of Pesticide Science
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• v.4 no.2
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• pp.21-28
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• 2000

A new fourty six 2-(4-(6-chloro-2-benzoxazolyloxy)phenoxy)-N-phenylpro- pionamide derivatives were synthesized and the herbicidal activities against rice plant and barnyard grass with pre-emergence in down land were measured. The structure activity relationships (SAR) between the activities and physicochemical parameters of the substituted(X) N-phenyl group in substrates were analyzed and discussed by Free- Wilson and Hansch method from the basis on the former study (Sung. et. al., 1999). The conditions of selective herbicide activity both the barnyard grass and rice plant are shown that the optimal hydrophobicity, $({\pi})_{opt.}=1.34$ and electron donating with field effect (F<0) of meta and ortho, para-substituted mono or disubstituent on the N-phenyl ring were found to contribute significantly. The herbicidal activities against barnyard grass are roughly the same as the results in up land whereas damage to rice plant in down land more increase than that of up land. Degradation products in water are 2-(4-(6-chloro-2-benzoxazolyloxy)phenoxy)propionic acid ((A)) (obs. pKa=4.35 & obs. logP=4.77) and 6-chloro-2-benzoxazolone (B) (obs. pKa=8.40 & obs. logP=2.90). These results were supposing that the hydrolysis product of substrates, (A) is comparatively absorbed in rice plant but not in barnyard grass. And it is assumed from the SAR equations that the 2,6-dimethyl-4-methoxymethyl group substituent ($pI_{50}=5.41$, 3g/ha) is selected as the most highest herbicidal activity against barnyard grass in green house.

• Journal of the Korean Geographical Society
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• v.44 no.4
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• pp.447-462
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• 2009

Kohyun River basin is located at southern parts of Taebaek Mountains and most of river basins consists of sedimentary rock. The aims of this study are to investigate the distribution characteristics and processes of fluvial terraces at Kohyun River, using scientific methods such as classification of fluvial landforms, analysis of geomorphological deposits, XRD and OSL age dating. In Kohyun River basin are three levels terraces from T1 to T3. Fluvial terraces are assumed to be erosional terraces according to deposited situation of alurium and existences of bedrock riverbed. From the result of OSL age dating, formation age of fluvial terrace 1(T1) is calculated about 37,000 yr.B.P.(MIS 3), and fluvial terrace 2(T2) is calculated about 113,000 yr.B.P.(MIS 5). Therefore, fluvial terraces at Kohyun River are assumed to be formed at warmer period in the glacial stages or cooler period in the interglacial stages. The incision rate of fluvial terrace 1 at Kohyun River is calculated to be 0.054m/ka, and the incision rate of fluvial terrace 2 is calculated to be 0.115m/ka. This results suggest to lower incision rate than other rivers in Korea because of low uplift rates and little discharge.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.8
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• pp.579-587
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• 2014

Various kinds of micro organic pollutants have frequently been detected from a water system. Therefore, it is considered to be very important part in the drinking water treatment system. And the research about removal process and processing efficiency have been being conducted briskly. In this study, the removal efficiency was evaluated using advanced water treatment process and nanofiltration process. The removal efficiency of nanofiltration process was very different according to physical and chemical characteristics of materials. The molecular weight of cutoff was the most influential factor in the removal efficiency. And when pKa value was higher than pH of raw water or Log Kow value was below 2, the removal efficiency of material was decreased. In case of oxidation reaction, the bigger the molecular weight of material was and the more hydrophobic a material was, the less oxidation reaction occurred. And the removal efficiency was decreased. Most unoxidized materials were removed by absorption. And the more actively oxidation reaction occurred by $H_2O_2$, the more absorption reaction increased.

• Journal of the Korean GEO-environmental Society
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• v.7 no.4
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• pp.35-41
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• 2006

This paper analyzed elution and ingredients of soil components which consist of soil and rocks in 6 regions in Yeongyang and Cheongsong to identify substantial matters that cause muddy water in Imha reservoir. We identified that more than 80% of major ingredients in collected soil and rocks are vermiculite(V), illite(I), kaolinite(Ka), quartz(Q), feldspar(F). Sodium and calcium are eluted in large quantities from soil of Sanseong and Cheongki. When calcium is in contact with water, much ions are eluted rapidly. We confirmed these ions are alkali minerals rising pH. We consider clay components distributed in Yeongyang as major cause of muddy water and rising pH of Imha reservoir because its ingredient calcite easily is dissolved in rainwater and splits other mineral particles into ${\mu}m$ sized particles.

• Journal of the Korean Chemical Society
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• v.43 no.3
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• pp.257-263
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• 1999

Ln-macrocyclic([20]DOTA) complexes, [Ln([20]DPTA)(NO_{3})(H_{2}O)](NO_{3})_{2} \cdotxH_{2}O{Ln(III)=Pr, Sm, Gd, Dy}, which had been synthesized from 2, 6-diformyl-p-cresol(DFPC), was placed in methanol for 2 days, and $[Ln([20]DPTA)(NO_{3})(CH_{3}OH)]^{2+}$ was formed. The equilibrium constants(L) for the substitution of coordinated $CH_{3}OH$ in the Ln-[20]DOTA complexes by various auxiliary ligands, $L_{a}(=monodentate ligands; pyridine, imidazole, triethylamine, diethylamine, piperidine) were determined spectroscopically at $25^{\circ}C$ and 0.1M. The pKa of auxiliary ligand is in the order of pyridine < imidazole < triethylamine < diethylamine < piperidine, however the K has shown the trend of pyridine < imidzole < diethylamine < piperidine < triethylamine.

• Applied Biological Chemistry
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• v.30 no.1
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• pp.1-8
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• 1987

The distribution of the surface charges in two kinds of peats and their physico-chemical properties have a been studied by means of the potentiometric titration and by ion adsorption in different strength of electrolytes. The organic matter contents were 43.3% and 53.7% in Yeong Yang peat and Peong Tack peat, respectively. Their X-ray diffractograms showed that quartz was dominant in both peats, and illite, kaolinite, hydrated-halloysite and feldspars were contained in a trace. Total acidic group contents was 1.257me/g in Poeng Tack peat that was a little more than of Peong Yang heat were pKa values of Yeong Yang and Poeng Tack peat were 13.1 and 12.65, respectively. The titration curves at different ionic strength of electrolytes crossed at pH 3.9 and 4.4 in Yeong Yang peat, and pH 3.8 and 4.0 in Peong Tack peat. The pH ranges of suspensions when the net surfacecharge of the peats varied from positive to negative value were $pH\;4.55{\sim}5.20\;(NaCl)$ and $pH\;3.95{\sim}5.70\;(CaCl_2)$ in Yeong Fang peat, and $pH\;4.15{\sim}5.40\;(NaCl)$ and $pH\;3.80{\sim}4.15\;(CaCl_2)$ in Peong Tack peat. Therefore it is apparent that the zero point of charge of these peats was about pH 4.0.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.305-308
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• 2005

The COMS, Korea's first geostationary multipurpose satellite program will accommodate 3 kind of payloads; Ka-Band communication transponder, GOCI (Geostationary Ocean Color Imager), and MI (Meteorological Imager). MI raw data will be transferred to ground station via L-band link. The ground station will perform image data processing for raw data, generate them into the LRIT/HRIT format, the user dissemination data recommended by the CGMS. The LRIT/HRIT are disseminated via satellite to user stations. This paper shows the COMS LRIT data generation procedure based on COMS LRIT specification and its verification results using the LRIT user station.