• Journal of the Korean Chemical Society
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• v.63 no.5
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• pp.335-341
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• 2019

Spirulina was cultured in Selenium solution and the total concentration was determined with isotope dilution technique. Low-molecular-weight-Selenium species for the water extract of Spirulina were separated and quantified with HPLC ICP/MS. Water extraction was used first and then protein enzyme (protease XIV) was used to digest and extract for the Se species in both water extract and residue. The total Se was $414.9{\pm}4.0{\mu}g\;g^{-1}$ and 77% existed in water extract while 22% remained in residue. Se species in supernatant was mostly inorganic selenate ($222.7{\mu}g\;g^{-1}$). After hydrolysis of protein, SeCys ($15.20{\mu}g\;g^{-1}$) and SeMet ($12.13{\mu}g\;g^{-1}$) were found. In residue, SeCys and SeMet were found with little inorganic Se. After protein hydrolysis of residue, more of Selenoamino acids SeCys ($9.35{\mu}g\;g^{-1}$) and SeMet ($18.23{\mu}g\;g^{-1}$) in addition to MeSeCys ($1.5{\mu}g\;g^{-1}$) were found. It is thought that inorganic selenium is mostly adsorbed on the surface of spirulina and can be easily removed by a simple distilled water extraction while most of organo-seleniums are remained in residue.

• 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 Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.545-551
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• 2020

Cause analysis of surface pitting crack on a waterjet impeller was conducted. The waterjet impeller was made from stainless steel duplex 2205, which is more resistant to corrosion and local corrosion than typical stainless steel 316L and 317L, and has high mechanical strength, making it a useful material in various marine structures and seawater desalination facilities. The measurements were taken by scanning electron microscopy (SEM) and molecular ecological detection. The chemical composition of S was examined by SEM in the area of pitting corrosion. The dsrAB gene was detected on the sample of the pitting corrosion of the impeller through molecular ecological detection. Therefore, pitting corrosion on the surface of a waterjet impeller was caused by sulphite-reducing bacteria (SRB). To prevent the spread of SRB, management is required through high temperature treatments (over 65℃), pH management, or the insulation of a hull and waterjet.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4
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• pp.49-57
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• 1992

This study was conducted to evaluate physical property change of asphalt cement chromatograms (by HP-GPC) were experimentally obtained from 3 types of AC-20 virgin ACs, 5 and 24-hour artificially aged ACs, and naturally aged 4 ACs that were recovered from 4 different roads. Absolute viscosity, kinematic visoosity and penetration were the physical properties tested. THF was used for mobil phase and RI detector was used as a detector for Hp-GPC testing. Correlation between each physical property change and the chromatogram variation was evaluated. Each chromatogram was divided into ten-equal-time slices. The percentage areas of 10 slices and each physical property were used for statistical correlation evaluation. Statistical analysis results showed that eaoh physical property had a strong correlation with the chromatogram characteristics. Aging was identified as a mechanism of change of molecular size distribution - increasing large size molecules and reducing coresponding samll size molecules.

• Journal of Conservation Science
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• v.36 no.2
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• pp.103-111
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• 2020

To compare the cleaning effect of solvents such as water and ethanol used to clean lacquer relics, the components extracted with various solvents were analyzed. A freshly dried lacquer sample and a lacquer sample exposed to ultraviolet radiation for 24 days were treated with water, ethanol, acetone, and hexane, and the dissolved material was detected by pyrolysis-gas chromatography-mass spectrometry. The amount extracted was significantly higher in acetone and ethanol than in hexane, a nonpolar solvent. Water, a highly polar solvent, was relatively efficient for extracting low-molecular-weight materials. After experiencing 24 days of ultraviolet radiation, the lacquer exhibited a significant increase of extracted materials compared with the nonexposed one. This may be due to the degradation of the urushiol chain in the form of polymers, resulting in the formation of low-molecular-weight polar substances, including dicarboxylic acids. In addition to the deterioration status of lacquer relics, such solvent extraction properties will be a crucial consideration in selecting the appropriate cleaning solvent.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.4
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• pp.27-32
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• 2011

Tin nanoparticles were synthesized at room temperature by a compulsive reduction reaction using tin(II) acetate and tin(II) chloride precursors. When an identical amount (0.015 g) of polyvinyl pyrrolidone (PVP) was added, it was concluded that the probability of abnormally big particles forming increased with an increase in PVP molecular weight, resulting in the wide distribution of Sn nanoparticles. Differential scanning calorimetry measurements were carried out using diethylene glycol solution containing synthesized tin nanoparticles. When the population of specific particles with sizes below 35 nm was adequate, the melting point depression peaks of tin nanoparticles corresponding to the specific size were observed besides an evaporation endothermic peak of DEG during the first heating. Because DEG was evaporated and tin nanoparticles in contact became molten and coarsened during the first heating, a melting peak of bulk tin was only observed at $232^{\circ}C$ during the second heating.

• Korean Journal of Food Science and Technology
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• v.28 no.5
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• pp.870-876
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• 1996

The physicochemical properties of chitin and chitosan produced from lobster shrimp (Metanephrups thomosonii) shell were investigated. Lobster shrimp chitin contained 6.84% nitrogen, 0.57% fat and 0.32% ash, while chitosan contained 7.52% nitrogen, 0.13% fat and 0.33% ash. Degree of deacetylation and molecular weight of chitosan were 67.5% and $9.1{\times}105$, respectively. Yields of chitin from the shell portion and chitosan from the chitin were 15.7% and 75%, respectively. Chitin and chitosan contained 2.64 and 1.39mg/g of residual amino acids, respectively, with both the most predominant being lysine. Chemical structures of the lobster shrimp chitin and chitosan have been investigated by the IR and solid state $^{13}C-NMR$ spectra.

• Korean journal of applied entomology
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• v.34 no.2
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• pp.140-146
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• 1995

Changes in protein content during oocyte development was measured and egg-specific protein was characterized from the eggs in Lucilia illustris. During normal development ovarian protein was rapidly increased at 72hr and reached maximum at 96hr after a protein meal, when the eggs were fully matured. Purified protein from the ovaries by gel filtration of DEAE-cellulose an Sephacryl S-200 was loaded on 7.5% native polyacrylamide gel electrophoresis and identified at ${R}_{f}$ 0.4 as egg-specific protein, which has a mol. wt of 110,000. A total of 13 amino acids in th egg-specific protein was identified and expecially asparagine, glutamic acid, and tyrosine were highly concentrated. Five fatty acids were also identified. It is suggested that there is a specific protein in the eggs of L. illustris except yolk protein synthesized and secreted by fat body.

• Korean Journal of Medicinal Crop Science
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• v.9 no.3
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• pp.192-197
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• 2001

This study was carried out to select proper SPME fiber for volatile component analysis in Zanthoxylum schinifolium and Z. piperitum. PDMS, PDMS/DVB and CAR/PDMS were better for single standard absorption analysis. PDMS and PDMS/DVB showed similar results in comparison between direct injection and the mixture of 24 single standards as well as the mixture of 10 single standards. PDMS and PDMS/DVB were not different each other in absorption patterns between direct injection and headspace SPME regardless of split ratio of GC injection port. However PDMS/DVB rather than PDMS was effective in absorbing the sesquiterpenes within 30-40 minutes as using the SDE extracts from Z. schinifolium and Z. piperitum.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.3
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• pp.353-358
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• 2006

Flavonoid and limonoid compounds were determined by HPLC on the methanol and ethanol extracts from citron seeds. The quantities of the compounds in these categories were higher in the ethanol extract than methanol extract. The types of these compounds were detected in larger numbers in the ethanol extract. The content of limonin was the largest in both methanol and ethanol extract among the detectable compounds ; 140.34 mg/100g and 170.98 mg/100g, respectively, and the contents of other compounds, caffeic acid, naringin, lutin, nomilin, were found in large amount in this order. The molecular weights of forty two compounds in ethanol extract were determined with mass spectrums and extracted ion current chromatograms by HPLC/MS.