• 한국해양학회지
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• v.2 no.1_2
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• pp.24-33
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• 1967

The variations of monthly mean sea levels along the coast of Korea anre studied graphic and harmonic methods with the data from 9 tides stations and compared with the variations of atmospheric pressure and the changes in density of sea water measured near some of the stations. The monthly mean sea level generally rises in Summer to Autumn, and falls in Winter to Spring and its range is from 20 cm to 50 cm. The variation of monthly mean sea level is of annual type, having one maximum and one minimum. The semi-range of annual components is 10.5 cm at Pusan and increases to the north in the west coast, to 20.8 cm at Inchon. It's phase is, on the whole, similar for the entire coast with about 210 (middle of August), except at Inchon, 200 . The variation of monthly mean sea level is mainly isostatic, or caused by those of sea water density and atmospheric pressure. Especially, the steric effect is predominant on the south- east coast around Pusan. However, in shallow long bays and estuaries on the west coast, the river runoff effect as well as local wind effect is also considerable. Magnitudes of annual variations at each stations are not constant, but widely variable from year to year. On the east and south coast, especially at Ulneungdo and Pusan the variations are large, which seem to be connected with the shifting of main current axes or current patterns in the offing.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.40 no.4
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• pp.383-390
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• 2014

The following conclusion was made from the 2D-QSAR model for the tyrosinase inhibitory activity according to the variation of the substituents R1 and R2 in analogues of compound 2-[(2,6-dioxocyclohexyl)methyl]cyclohexane- 1,3-dione (1-23). The best optimized 2D-QSAR model was $Obs.pI_{50}=-0.295({\pm}0.031)TDM$ $-0.120({\pm}0.014)DMZ+0.135({\pm}0.050)DMX.R_2+6.382({\pm}0.17)$, and the correlation $r^2=0.905$) of which was greater than its predictability ($q^2=0.843$). The magnitude of the effect of tyrosinase inhibitory activities was in order of TDM > $DMX.R_2{\geq}DMZ$, and it tended to increase as the hydrophobicity of substrate molecule (ClogP > 0) as well as the steric favor of substituent $R_1$ increased. The analysis of the model implies that inhibitory activity of substrate molecule will increase as $DMX.R_2$ (Dipole moment X component of $R_2$-substituent) increases, while TDM (Total Dipole Moment) and DMZ(Dipole Moment of Z-Component) decrease. As such, it is deemed feasible to conclude, that in order to increase the inhibitory effect, it would be rather desirable to replace the polar groups within the molecules with non-polar functional groups.

• Polymer(Korea)
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• v.30 no.5
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• pp.432-436
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• 2006

The new dinuclear CGC (constrained geometry complexes) with indenyl and methyl sub-stituted indenyl and polymethylene bridge have been synthesized, and the copolymerization of ethylene and styrene has been studied in the presence of methylalumionoxane. The activity of 12-methylene and 9-methylene bridged dinuclear CGC were 4 times higher than that of 6-methylene bridged dinucleay CGC. This result might be understood by the implication that the steric effect rather than the electronic effect nay play a major role to direct the polymerization behavior of the dinuclear CGC. The dinuclear CGCs are very efficient to incorporate styrene in backbone. The styrene contents in the formed co-polymers ranged from 6 to 45 mol% according to the polymerization conditions. The melting temperature of copolymers disappeared at high content of styrene (about 11 mol%) There is no styrene-styrene diblock sequence in copolymers. This result Indicates that the dinuclear CGC are very effective to generate random copolymer of ethylene and styrene.

• Journal of the Korean Chemical Society
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• v.36 no.2
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• pp.205-211
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• 1992

The $2{\nu}_{C=0}$ + amide III combination band spectrum of acetamide (AA) was obtained in very dilute solutions of AA+lanthanide shift reagents (LSR) in carbon tetrachloride over the range of $15^{\circ}$ to $45^{\circ}C$. It was found that only 1 : 1 AA-LSR complex is formed by the interaction between carbonyl oxygen of AA and central metal ion(Ln(Ⅲ)) in LSR. The thermodynamic parameters for Ln(III)${\cdot}$O=C bond were determined by computer analysis of concentration and temperature dependent spectra. ${\Delta}H^{\circ}$ for the coordination of AA to Eu$(dpm)_3$, Yb$(dpm)_3$, and Pr$(dpm)_3$ have been found to be -39.1, -28.4, and -25.5 kJ/mol, respectively. It has shown that this type of ion-dipole interaction is more than twice stronger compared to the dipole-dipole interaction in the amide linkage, and largely depending on the steric hindrence effect by the bulky dpm groups around central metal ion (Ln(III)) rather than the ionic potential effect of central metal ion itself.

• Clean Technology
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• v.20 no.4
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• pp.383-389
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• 2014

$CO_2$ absorption processes have a good potential for large scale capture of $CO_2$ but a large amount of absorbing solution has to be regenerated, undesirably increasing the consumption of energy such as sensible heat and latent heat of vaporization. In this study, a cooling crystallization process which would separate the $CO_2$-rich potassium bicarbonate crystals from $CO_2$-lean water was developed to reduce the energy penalty. Sterically hindered alkanolamine additives were used to enhance the $CO_2$ removal efficiency and their antisolvent effect on the crystallization was found in a continuous cooling crystallizer. The production yields of crystals were increased in the sequence of 2-amino-2-methyl-1-propanol (AMP) < 2-amino-2-methyl-1,3-propanediol (AMPD) < 2-amino-2-hydroxymethyl-1,3-propanediol (AHPD), which are related to the number of hydroxyl groups in the additive molecules. Using $^{13}carbon$ nuclear magnetic resonance, the additives favored the formation of bicarbonate ions by steric hindrance effect and increased the supersaturation of $KHCO_3$. It is shown that the additives increase the mean size of crystals and crystal growth rate by increasing supersaturation. The additives are promising for enhancing the $CO_2$ removal efficiency and reducing the regeneration energy cost of $CO_2$ absorbing solution by promoting $KHCO_3$ crystallization.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.3
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• pp.236-247
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• 2011

This study investigates sea level (SL) rise due to global warming in the Northwestern Pacific (NWP) and Seas around the Korean peninsula (KP) using outputs of IPCC AR4 climate models. Particularly, components of the SL rise induced by a local steric effect, which was not considered in most climate models, were computed using model-projected 3-dimensional temperature and salinity data. Analysis of the SL data shows that the ratio of the SL rise in the NWP and KP was about two times higher than that in global mean and particularly the ratio in the Kuroshio extension region was the highest. The SL rises over 100 years estimated from MPI_ECHAM5 and GFDL_CM2.1 model by A1B scenario considering the thermosteric effect were 24 cm and 28 cm for the NWP and 27 cm and 31 cm for the Seas around the KP, respectively. Statistical analysis reveals that these SL rises are caused by the weakening of the Siberian High in winter as well as variations of pressure system in the NWP and by the resultant change of water temperature. It also found that the highest SL rise in the Kuroshio extension region of the NWP was connected with the large increase of water temperature in this area.

• The Korean Journal of Pesticide Science
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• v.2 no.3
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• pp.45-51
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• 1998

A series of bis-aromatic ${\alpha},{\beta}$-unsaturated ketone derivatives with mesaured fungicidal activities in vivo against rice blast(Pyricularia oryzae), tomato leaf blight (Phytophtora infestans) and barley powdery mildew(Erysiphe graminis) were studied by using quantitative structure activity relationship equations. The QSAR model for the activity of phenyl substituents, $1{\sim}11$, clearly reveals three important factors, namely, resonance(R<0), optimal molecular hydrophobicity(${\pi})_{opt.}=0.38$) and optimal distance($((L_{1})_{opt.}=5.69({\AA}))$ of substituent, respectively. But in case of 2-pyridyl substituents, $12{\sim}28$, the activity were governed by optimal molecular refractivity $((M_{R})_{opt.}=8.04{\sim}39cm^{3}/mol)$, steric effect(Es<0) and LUMO energy(e.v). The fungicidal activity relationship of phenyl and 2-pyridyl substituents against Erysiphe graminis have been proportioned.

• Journal of the Korean Chemical Society
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• v.37 no.5
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• pp.503-512
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• 1993

The purpose of this study was to investigate the retention behavior of phenols and to predict their retention in RPLC. The retention data of twenty-five phenols were measured on a $\mu-{Bondapak}\;C_{18}$ and a polymeric $C_{18}$ columns with methanol-water and acetonitrile-water as a mobile phase. From the observation of enthalpy-entropy compensation phenomenon, the following conclusions are drawn with regard to the retention mechanism: 1) the retention mechanism of nitrophenols in different from that of metheyl-and chlorophenols in both mobile phase; 2) in methanol-water mobile phase, the retention mechanism of methyl-and chlorophenols is consistent in the range of methanol-water composition; 3) on the other hand, in the case of acetonitrile-water mobile phase, the retention mechanism depends on the volume fraction of acetonitrile. It means that the retention mechanism can not be explained only by a simple interaction. Based on retention data as compared with two columns, it may be said that the hydrophobic interaction of phenols with polymeric $C_{18}$ column was greater than that with monomeric $C_{18}$ column. The equations for predicting the retention of phenols were derived by using hydrophobic substituent constant $(\pi)$ and the sum of Hammett's constant $(\sigma)$ and Taft's steric constant $(E_s)$.

• Journal of Environmental Health Sciences
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• v.21 no.3
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• pp.38-47
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• 1995

The Bioconcentration factor (BCF) is used as an important criterion in the risk assessment of environmental contaminants. Also it can be used as indicator of biomagnification of environmentally hazardous chemicals through food-chain as well as a tool for ranking the bioconcentration potential of the chemicals in the environment. This paper reports the measured BCF value on Chlorothalonil in Carassius auratus(goldfish), under steady state, and examined correlation between the BCF value and the partition coefficient or acute toxicity or physicochemical properties. Carassius auratus(goldfish) was chosen as test organism and test period were 3-day, 5-day. Experimental concentrations were 0.005, 0.01 and 0.05 ppm. Chlorothalonil in fish tissue and in test water were extracted with n-hexane and acetonitrile. GC-ECD was used to detecting and quantitating of Chlorothalonil. Partition coefficient was determined by stir-flask method. $LC_{50}$ was determined on Chlorothalonil. Carbaryl and BPMC. The obtained results were as follows. 1. It was possible to determine short term BCFs of Chlorothalonil through relatively simple procedure in environmental concentrations. 2. $BF_3$ of Chlorothalonil in concentration of 0.005, 0.01 and 0.05 ppm were 2.1866$\pm$0.23446, 3.5269$\pm$0.23517, 10.2045$\pm$0.18053 and BCFs were 6.6543$\pm$0.55257, 6.9774$\pm$0.02500, 23.4576$\pm$2.06884, respectively. 3. Chlorothalonil concentration in fish extract and BCFs of Chlorothalonil were increased as increasing test concentration and prolonging test period. 4. Fate of test-water concentration on Chlorothalonil was greater than that of control-water con-centration. It is considered that greater fate of test-water concentration on Chlorothalonil is due to hydrolyzing nitrile group under the mild condition and substituting chloro group by some aromatic compounds in test water. 5. Determined logP of Chlorothalonil was 2.80. And determined $LC_{50}$ of Chlorothalonil in time of 24, 48, 72 and 96 hr were 0.1684, 0.1402, 0.1400, 0.1352(mg/l) respectively. And $LC_{50}$ of Carbaryl in above times were 19.918, 18.635, 18.466, 18.12(mg/l) respectively. $LC_{50}$ of BPMC were 10.248, 9.166, 9.087, 8.921(mg/l) respectively. 6. It is suggested that the BCF of Carbamates depend on partition coefficients. But BCF of Chlorothalonil, organochlorine pesticide, would be strongly influenced by steric, electronic effect of substituents than partition coefficient.

• Journal of the Korean Applied Science and Technology
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• v.34 no.2
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• pp.357-366
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• 2017

Natural pigments are materials that express color and have been used in foods, cosmetics, medicine and so on. Since natural pigments are extracted from animals and plants, they are not uniform in size. Red pigments in particular are more lipophilic than other color pigments and tend to aggregate easily in aqueous solutions which make it difficult to reproduce the specific color due to size change. Found to be an allergen and the growing aversion for it to be used in foods, cochineal pigment, an animal pigment used for red pigments is being used less. In this study, red vegetable pigment lycopene extract and gardenia yellow was made uniform in size by ball-milling, then asymmetrical flow-field flow fractionation (AsFlFFF) and dynamic light scattering (DLS) were used to measure the size, and a color meter was used to confirm the color. Experimental results showed that the pigment particles were large in size and size distribution was wide before milling, but the size of the particles decreased and size distribution narrowed after milling. Color meter measurements showed that as the milling time increased, the size of the pigment particles decreased and the brightness, redness, and yellowness increased indicating a bright red color.