• Resources Recycling
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• v.31 no.5
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• pp.20-25
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• 2022

In this study, the applicability of microalgae was evaluated for eco-friendly decontamination of cesium-137 (Cs-137) and strontium-90 (Sr-90), which are radioactive nuclides contained in radioactive waste. The monolithic radioactive solution used in the experiment was manufactured at a concentration of 1.5 Bq/mL Cs-137 and 1.0 Bq/mL Sr-90 by diluting a standard radioactive solution and distilled water. This experiment used two types of microalgae, Chlorella Vulgaris was used for Sr-90 decontamination and Hematococcus pluvialis for Cs-137 decontamination. The experimental method is to put the microalgae cultured for 2 weeks into a bottle with a semi-permeable membrane, and then put the bottle in which the microalgae was put into the manufactured radioactive solution, so that the microalgae and the radioactive solution react through the semi-permeable membrane for 48 hours. For the radioactivity concentration analysis of each sample, a gamma-ray nuclide analyzer was used for Cs-137, a γ-ray isotope, and a Liquid Scintillation Count(LSC) was used f or Sr-90, a β-ray isotope. As a result of the experiment, it was confirmed that about 88.0 % of Cs-137 and about 89.7 % of Sr-90 could be decontaminated, and about 98.6 % of Sr-90 was finally able to be decontaminated by the two-stage decontamination method.

• Analytical Science and Technology
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• v.21 no.6
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• pp.518-525
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• 2008

Mandipropamid is a new mandelamide-type fungicide to control foliar Oomycete pathogens in some vegetables. An analytical method was developed to determine mandipropamid residues in agricultural commodities using high-performance liquid chromatography (HPLC) and liquid chromatography/mass spectrometry (LC/MS). Mandipropamid was extracted with methanol from grape, tomato, green pepper, Chinese cabbage and potato samples. The extract was diluted with saturated sodium chloride solution and distilled water, and dichloromethane partition was followed to recover the mandipropamid from the aqueous phase. Florisil column chromatography was employed to further remove interfering co-extractives prior to HPLC analysis. Reverse-phased HPLC was successfully applied to determine mandipropamid in sample extracts with the detection at its ${\lambda}_{max}$ (223 nm). Overall recoveries of mandipropamid from fortified samples averaged $99.8{\pm}1.7$ (n=6), $89.3{\pm}5.3$ (n=6), $98.7{\pm}2.2$ (n=6), $99.7{\pm}6.8$ (n=6) and $91.1{\pm}3.1$ (n=6) for grape, tomato, green pepper, Chinese cabbage and potato, respectively. Limit of quantification of the method was 0.02~0.04 mg/kg for all samples. A LC/mass spectrometry with selected-ion monitoring was also provided to confirm the suspected residue. The proposed method was reproducible and sensitive enough to determine the terminal residue of mandipropamid in agricultural commodities.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.2
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• pp.283-299
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• 2017

The leakage of tunnel causes the long-term durability of the structures such as concrete lining to deteriorate. The cause of durability degradation can be various substances contained in groundwater such as chloride, sulphate, water, and gas. In this study, a series of test were carried out to determine the watertightness performance and the resistance to salt water of the spray-applied membrane used as non-structural rock support or as a waterproof material for tunnels. As a result, it was found that the penetration of water could occur in a specimen, and the reason was that the internal pores generated by the mixing of the liquid polymer and the powder material and the internal pores were connected by the water pressure. The tensile strength of the test specimens immersed in distilled water and saline water was found to be reduced to less than half of the tensile strength in normal condition. In addition, The elongation was measured to be higher in distilled water than in salt water. However, this result will require further investigation.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.1120-1125
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• 2012

To assess fertilizer value of an quasi-aerobically fermented liquid clipped-grass fertilizer, aerobic incubation experiment using two texturally contrasting loam (L) and sandy loam (SL) soils was conducted for 60 days to investigate temporal variations in N mineralization pattern of the liquid fertilizer applied. To do so, the quasi-aerobically fermented liquid clipped-grass fertilizer was prepared, applied to each soil at a rate of 200 kg-N $ha^{-1}$ and aerobically $25^{\circ}C$ in the dark. During incubation, soil water content was adjusted to field moisture capacity (-33 kPa of soil matric potential) by adding distilled water as necessary to maintain their initial weights. At desired time of incubation (0, 1, 5, 10, 20, 40, and 60 days after incubation), soil was sampled and analyzed for inorganic nitrogen ($NH_4{^+}$-N and $NO_3{^-}$-N) concentrations, pH, EC, total carbon contents and total nitrogen contents. Concentrations of $NH_4{^+}$-N began to decrease right after incubation for L soils, and 10 days after incubation for SL soils, while those of $NO_3{^-}$-N began to increase onset of $NH_4{^+}$-N disappearance. The results of this study showed that quasi-aerobically fermented liquid clipped-grass fertilizer could serve as an alternative to chemical N fertilizer.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.8
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• pp.872-878
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• 2014

This paper proposes a measurement method of the complex relative permittivity of semi-solid materials using a new cavity structure. Semi-solid materials are positioned in the proposed cavity where an aperture exists on each corner of the upper part and a ground plane is separated. In order to show the validation of the proposed method, we measured the complex relative permittivity of distilled water and 0.9 % saline by sensing a shift of resonant frequency and using Critical-Points Method, and compared the results with those derived from the Cole-Cole equation.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1783-1790
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• 2013

A simultaneous analytical method has been developed for the fluorimetric determination of haloacetonitriles (HANs) [dichloroacetonitrile (DCAN), trichloroacetonitrile (TCAN), dibromoacetonitrile (DBAN), haloacetamides [dichloroacetamide (DCAD), and trichloroacetamde (TCAD)] in drinking water by using the combined on-line perconcentration/reversed phase liquid chromatography (RPLC)-postcolumn detection system. This on-line perconcentration system was achieved by employing a precolumn packed with a commercial solid phase extraction (SPE) sorbent for the enrichment and purification of the target analytes. The haloacetonitriles and haloacetamides were separated on CN analytical column in a 7.5% methanol-0.02 M phosphate buffered mobile phase at pH 3. The column effluents were reacted with postcolumn reagents of ophthaldialdehyde (OPA) and sulfite ion at pH 11.5, to produce a highly fluorescent isoindole fluorophore, which were measured with a fluorescence detector. Under the optimized conditions for RPLC and the postcolumn derivatization system all of the coefficient of determination of the standard calibration curves for the target analytes were over 0.99 and had a linear range from 5 to 100 ${\mu}g/L$. The detection limits showed 1.6 ${\mu}g/L$ for DCAD, 0.1 ${\mu}g/L$ for TCAD, 0.6 ${\mu}g/L$ for DCAN, 1.6 ${\mu}g/L$ for TCAN and 1 ${\mu}g/L$ for DBAN, and the recoveries were ranged from 64 to 99% except for DCAD with precisions less than 4.9% in distilled water, and from 72(${\pm}4%$) to 116%(${\pm}2%$) in tap water.

• Geomechanics and Engineering
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• v.15 no.5
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• pp.1091-1100
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• 2018

In this study, the relationships between hydraulic conductivity of GCLs and physico-chemical properties of bentonites were assessed. In addition to four factory manufactured GCLs, six artificially prepared GCLs (AP-GCLs) were tested. AP-GCLs were prepared in the laboratory without bonding or stitching. A total of 20 hydraulic conductivity tests were conducted using flexible wall permeameters ten of which were permeated with distilled deionized water (DIW) and the rest were permeated with tap water (TW). The hydraulic conductivity of GCLs and AP-GCLs were between $5.2{\times}10^{-10}cm/s$ and $3.0{\times}10^{-9}cm/s$. The hydraulic conductivities of all GCLs to DIW were very similar to that of GCLs to TW. Then, simple regression analyses were conducted between hydraulic conductivity and physicochemical properties of bentonite. The best correlation coefficient was achieved when hydraulic conductivity was related with clay content (R=0.85). Liquid limit and plasticity index were other independent variables that have good correlation coefficients with hydraulic conductivity (R~0.80). The correlation coefficient with swell index is less than other parameters, but still fairly good (R~0.70). In contrast, hydraulic conductivity had poor correlation coefficients with specific surface area (SSA), smectite content and cation exchange capacity (CEC) (i.e., R < 0.5). Furthermore, some post-test properties of bentonite such as final height and final water content were correlated with the hydraulic conductivity as well. The hydraulic conductivity of GCLs had fairly good correlation coefficients with either final height or final water content. However, those of AP-GCLs had poor correlations with these variables on account of fiber free characteristics.

• Journal of Food Hygiene and Safety
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• v.8 no.1
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• pp.55-61
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• 1993

Soil samples and the intestinal contents of arthropods, mollusca, pisces, aves, and mammals were examined for the presence of Clostridium botulinum. Demonstration of Clostridium botulimun was accomplished by identifying its toxin in liquid cultures inoculated with soil or material from the alimentary tract of tested animals with toxin neutralization tests in addition to morphological, cultural and biochemical tests. Incidences of Clostridium botulinum in tested samples were 5.0% in soil, 6.7% in mammal and 8.7% in fish, respectively. All of the positive cultures were identified as Clostridium botulinum type E and any other type was not demonstrated throughout the survey. Canned foods and solid ham/sausage mixture formulated as can with distilled water were inoculated with Clostridium botulinum type E and checked for toxin production by using the mouse bioassay. Clostridium botulinum type E toxin was produced as a large quantity in canned foods of fish, shell, meat and ham and, however, no significant toxin was detected in sausages and fruit samples.

• Korean Journal of Food Science and Technology
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• v.33 no.4
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• pp.416-422
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• 2001

The migration of alkylphenols from PVC packaging materials (wrap, sheet and gasket) into food simulants and foods were analyzed by reversed-phase high-performance liquid chromatography with fluorescence detection and gas chromatography with mass selective detection. Only seven nonyl phenol isomers were detected in three types of PVC food packaging materials and the content of nonyl phenol of wrap was higher than those of sheet and gasket. The contents of nonyl phenol migrated from fatty food simulants (n-heptane) were higher than those from aqeous food simulants (distilled water, 4% acetic acid and 20% ethanol) and increased with increase in temperature. Nonyl phenol in fruit juice, infant formula, and beverage was migrated from PVC gasket, olefin gasket, and olefin bottle cap, respectively. Nonyl phenol was also detected from foods even before contacting with the packaging materals.

• The Korean Journal of Pharmacology
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• v.18 no.1
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• pp.17-22
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• 1982

Zizyphus seed(Zizyphus vulgaris Lamark var. Spinosus Bunge) has long been used as hypnotics and sedatives in oriental medicine, and it is reported that the Zizyphus seed elicited a variety of pharmacologic actions besides CNS depression. Present study was undertaken to investigate the effects of Zizyphus seed on the central nervous system and on the blood pressure. The effect of Zizyphus seed on the central nervous system was measured by the influence of thiopental sleeping time and by inhibition of chemical convulsion (strychnine and pentylenetetrazol induced). Blood pressure changes by Zizyphus extract and its mode of action were investigated. The ground Zizyphus seed was extracted with hexane and methanol, consecutively and the supernatants were discarded. The precipitate was re-extracted with distilled water and the supernatant was evaporated to a dark-brownish sticky liquid, which was used as Zizyphus seed extract in this study after dissolving in saline prior to experiment. The results are as follows. 1) Zizyphus seed extract caused marked prolongation of the thiopental sleeping time in mice. 2) The chemical convulsion by strychnine and pentylenetetrazol, and the mortality by them in chicks were not affected by pretreatment of Zizyphus seed extract. 3) Zizyphus seed extract produced transient fall of blood pressure in the cat, and this hypotentive effect was blocked partially by atropine but not affected by bilateral vagotomy and/or hexamethonium, nor propranolol and, chlorpheniramine and/or cimetidine. With the above results, it may be suggested that the water extract of Zizyphus seeds contains components producing CNS depression and hypotension. Furthermore it is felt that the cholinergic effect, but not the adrenergic or histaminergic, is partly responsible for the hypotensive effect of Zizyphus seed extract.