• Korean Chemical Engineering Research
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• v.44 no.5
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• pp.453-459
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• 2006

D-tryptophan and N-CBZ-D-phenylalanine were separated using ionic liquid as additives for the mobile phase in high performance liquid chromatography (HPLC). The ionic liquid of 1-butyl-3- methylimidazolium tetrafluoroborate (${[BMIm]}^+{[BF_4]}^-$) was used. Mobile phases were 65％, 70％, and 80％ methanol in water with addition of different concentrations (0.5, 1.0, 1.5, 2.0, 4.0, 6.0, 8.0, 10.0, 12.0, and 15.0 mmol/L) of the ionic liquid. The experiments were performed on stainless steel column, $3.9{\times}300mm$ i.d., packed with $15{\mu}m$ octadecyl-bonded silica gel at laboratory.The retention factor of D-tryptophan was not negligibly changed while that of N-CBZ-D-phenylalanine was decreased. The resolution between the two components were affected by the contents of methanol and ionic liquid in the mobile phase. With the small content of methanol and the high concentration of ionic liquid, the resolution was improved.

• Journal of the Korean earth science society
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• v.21 no.2
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• pp.128-136
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• 2000

To understand the variation and transport pattern of suspended matters, salinity, tidal current and suspended matters in semiclosed Muan Bay have been monitored during winter and summer. The suspended matters show considerably seasonal variations with low concentration and homogeneity in the water column during winter season, but with high concentration and layering during summer season. Particularly, during summer season, the freshwater and the suspended matters influxed by the gate operation of the Youngsan River sea-dike are transported northward in accordance with the would flow into the inner-bay by relaxed flood currents after the construction of sea-dike and sea-walls in the Mokpo coastal zone. But, in the south bay-mouth, those matters outflow through the bay-mouth, resulting from tidal ebb dominance and asymmetry in the west bay-mouth. The residual suspended matter flux is much higher in the south bay-mouth(-0.0955kg/m ${\cdot}$ sec) than that of west bay-mouth(0.0078kg1m ${\cdot}$ sec). Accordingly, The Muan Bay is interpreted as erosion-dominated environments, and the erosion somewhat progresses in the intertidal flat of the bay.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.3
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• pp.23-31
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• 1987

In land treatment systems for organic waste removal, especially rapid intiltration method is well known as less climatic restrictions and less field area requirements as against the others. Therefore the present study on rapid infiltration is aimed to survey the waste removal rate, infiltration rate, variation of dissolved oxygen due to biological oxygen absorption and pH decrement using pilot infiltration column filled with permeable soil(sand) as media, also to find the waste load(COD) per unit area and nitrate conversion ratio from TKN. The results obtained here are as follows. 1) When the depth of sand layer is more than 1 meter, the COD removal would be reached steadly to 90% or more under the infiltration rate below 15~20cm/day, and would be no problem due to leached organic pollutants considering the depth of ground water table. 2) The COD removal per unit area($m^2$) can readily be expected to 10~14g/day with proper operation, and the decomposition of substrate would be attained mostly at the surface layer of the media. 3) Generally the conversion of TKN to the $NO_3{^-}$-N is seemed to be proportional to the COD removal rate if provided proper retention time.

• Korean Journal of Pharmacognosy
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• v.39 no.3
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• pp.199-202
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• 2008

A high performance liquid chromatographic (HPLC) method for the simultaneous determination of hesperidin and glycyrrhizin was established for the quality control of traditional herbal medicinal preparation, Pyungwi-san (PWS). Separation and quantification were successfully achieved with a Waters XTerra RP18 column ($5{\mu}m$, 4.6 mm I.D. ${\times}$ 150 mm) by gradient elution of a mixture of acetonitrile and water containing 0.03% phosphoric acid (pH 2.03) at a flow rate of 1.0 ml/min. The diode-array UV/vis detector (DAD) was used for the detection and the wavelength for quantification was set at 230 nm. The presence of hesperidin and glycyrrhizin in this extract was ascertained by retention time, spiking with each authentic standard and UV spectrum. All four compounds showed good linearity $(r^2>0.995)$ in a relatively wide concentration ranges. The R.S.D. for intra-day and inter-day precision was less than 7.0% and the limits of detection (LOD) were less than 60 ng. The mean recovery of each compound was 99.0-105.6% with R.S.D. values less than 4.0%. This method was successfully applied to the determination of contents of hesperidin and glycyrrhizin in three commercial products of PWS. These results suggest that the developed HPLC method is simple, effective and could be readily utilized as a quality control method for commercial PWS products.

• Korean Journal of Food Science and Technology
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• v.28 no.4
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• pp.684-688
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• 1996

In order to search for antithrombotic peptides from soybean paste, the inhibitory activity of water extract of soybean paste and its peptide fractions on ADP-induced aggregation of washed platelets was assayed. Soybean paste extract treated with ultrafiltration (M.W. cut off, 3,000 daltons) was found to have inhibitory activity of 90% at the dose of $96\;{\mu}g/ml$ by the method of turbidometric aggregometer. Soybean paste extract was fractionated to 19 fractions (No. B-18) by Dowex 50W X-2 ion exchange column chromatography and activity test was performed by the microplate method. All of the fractions had antithrombotic activity $(IC_{50},\;101,000\;{\mu}g/ml)$, and most fractions had higher activity than positive control, RGDS $(IC_{50}.\;205\;{\mu}g/ml)$. Especially, basic fractions No.16-18 showed higher activity than soybean paste extract $(IC_{50},\;30\;{\mu}g/ml)$. The fraction No.16 with the highest activity $(IC_{50},\;10\;{\mu}g/ml)$ was purified and analysed for amino acid composition. The results showed that histidine, arginine, and alanine were major residues in the peptide part of the fraction.

• Journal of the Korean Chemical Society
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• v.21 no.4
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• pp.293-303
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• 1977

Cellulosic organic solid wastes such as bark and sawdust, and filter papers as a pure cellulose were pyrolyzed at $300^{\circ}C$ under nitrogen current and mixed current of nitrogen and air. Amounts of condensates collected in air, water, and dry ice-acetone cooling traps, noncondensable gases, and carbonized residues were surveyed. The components of volatile liquids condensed in dry ice-acetone trap were separated by means of gas chromatograph and identified by retention times and syringe reactions. Pyrolysis under nitrogen current produced 13.4∼29.6${\%}$ of tar, 0.01∼0.12${\%}$ of aqueous liquids, 0.24∼1.43${\%}$ of volatile liquids, 9.84∼42.41${\%}$ of noncondensable gases, and 44.0∼65.81${\%}$ of carbonized residues. Pyrolysis under mixed current decreased tar and condensable liquids, but increased noncondensable gases.Volatile liquids collected under nitrogen current separated into the same 19 components by Porapak Q column regardless of the materials and only difference among materials was relative amounts of components. Volatile liquids collected under mixed current separated into six components and mainly lower molecular weight compounds such as methanol and formaldehyde were produced. According to the retention times and syringe reactions, methanol, formaldehyde, acetone, acetaldehyde, acetic acid, and three other compounds presumably containing hydroxyl group in the molecular structure were identified out of 19 compounds.

• Korean Journal of Agricultural Science
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• v.10 no.2
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• pp.365-370
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• 1983

Cellooligosaccharides were prepared from microcrystalline cellulose by acetolysis, deacetylation, and chromatographic fractionation, to determine the optimum time of treatment with acetolysis mixture. The fractionation was accomplished by ethanol-water gradient elution on chromatographic column composed of stearic acid-treated mixture of charcoal and Celite. The amount of initial acetolysis product was increased with the reaction period, however, the acetylated mixture of longer reaction period appeared to contain the greater bulk of methanol-insoluble material. Better yields of most of oligosaccharides were obtained with 3-hr acetolysis. When the reaction time was extended to 4-hr, yields of shorter chain oligosaccharides increased at the expense of the The yields obtained with 3-hr acetclys is from 68.2g of Sigmacell Type 19 were : cellotriose, 1.36g(2.0%) ; -tetraose, 1.64g(2.4%) ; -pentaose, 1.16g(1.7%) ; -hexaose, 0.82g(1.2%) ; and -heptaose, 0.21g(0.3%).

• Korean Journal of Environment and Ecology
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• v.29 no.5
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• pp.743-752
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• 2015

We studied the spatio-temporal microalgal (phytoplankton and benthic diatoms) and environmental changes of the Hajeonri intertidal zone from February to November 2014. Seawater and phytoplankton analysis were conducted all through the months. The species, composition and abundance of phytoplankton and environmental factors were measured. As a result, diatom was dominant among a total of 113 species identified. On a seasonal basis (Feb. May, Aug., Nov.), we carried out studies on benthic diatoms on the surface of the sediments and their habitats at nine stations on the transect line at Hajeonri at low tide. The grain of the surface sediments was mainly composed of sandy silt and sandy mud. Organic pollution level was low. Benthic microalgal biomass (chlorophyll ${\alpha}$) was high in the spring and summer. A total of 163 benthic diatom species were identified. Navicula sp.1 and Paralia sulcata were dominant over the study period. Five diatom species were observed both in water column and on surface sediment at the same time.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.4
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• pp.225-243
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• 2014

As the economic matters are involved, applying the WEC, which is used for controlling waves as well as utilizing the wave energy on existing breakwater, is preferred rather than installing exclusive WEC. This study examines the OWC mounted on a pressurized air chamber floating breakwater regarding the functionality of both breakwater and wave-power generation. In order to verify the performance as a WEC, the velocity of air flow from pressurized air chamber to WEC has to be evaluated properly. Therefore, numerical simulation was implemented based on BEM from linear velocity potential theory as well as Boyle's law with the state equation to analyze pressurized air flow. The validity of the obtained values can be determined by comparing the previous results from numerical analysis and empirically obtained values of different shapes. In the actual numerical analysis, properties of wave deformation around OWC system mounted on fixed type and floating type breakwaters, motions of the structure with air flow velocities are investigated. Since, the wind power generating system can be hybridized on the structure, it is expected to be applied on complex power generation system which generates both wind and wave power energy.

• Korean Journal of Food Science and Technology
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• v.45 no.2
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• pp.235-240
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• 2013

To analyze aflatoxin $M_1$ ($AFM_1$), we dissolved infant formula in warm water and cleaned it by using an immunoaffinity column (IAC). The amount of $AFM_1$ was determined by high-performance liquid chromatography coupled with fluorescence detection. $AFM_1$ was detected in 281 of 439 samples. Thus, the detection rate of $AFM_1$ was 64.0%. The average concentration of $AFM_1$ in positive samples was 2.6 ng/kg (of prepared formula). The estimated daily intake (EDI) of $AFM_1$ through infant formula was 0.087-0.646 ng/kg body weight/day and the additional number of cases of liver cancer associated with exposure to $AFM_1$ would be 0.003-0.020 cancer cases/1,000,000. Because there is less than 1 cancer case/1,000,000 per year, the exposure to $AFM_1$ through infant formula in Korea is considered to be an unlikely human health concern.