• Journal of Environmental Science International
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• v.10 no.4
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• pp.287-292
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• 2001

A packed bed of volcanic rock was used as deodorizing material to remove hydrogen sulfide($H_2$S) from air in a laboratory-scale column, and was inoculated with Thiobacillus sp. as $H_2S$ oxidizer. The effects of volcanic rock particle size distribution on system pressure drop were examined. Various tests have been conducted to evaluate the effect of $H_2S$ inlet concentration and CBCT(Empty Bed Contact Time) on $H_2S$ elimination. The pressure drop for particles of size range from 5.6 to 10 mm was 14 mm$H_2S$/m at a representative gas velocity of 0.25m/s. Biofilter using scoria and Thiobacillus sp. could get the stable removal efficiencies more than 99.9% under $H_2S$ inlet concentrations in the range from 30 to 1,100ppm at a constant gas flow rate of $15.2{\ell}$/min. $H_2S$ removal efficiencies greater than 99% were observed as long as EBCT was longer than 8sec at the 250ppm of $H_2S$ inlet concentration. When EBCT was reduced to 5.5 sec, $H_2S$ removal efficiency decreased by about 12 percent. The maximum $H_2S$ elimination capacity was determined to be 269g-$H_2S/m^3{\cdot}hr$.

• Toxicological Research
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• v.16 no.2
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• pp.125-131
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• 2000

The ethanol extract of Rhus verniciflua Stokes (RVS), the Korean Lacquer tree, was subsequentely isolated and fractioned into two portions using distilled water (SED) and 99% ethanol (SEE) as elution buffers through silica gel column (4x28 em, 22 $\AA$. 28~200 mesh). To know the antioxidative effect of the RVS extracts, primary hepatocytes were exposed to hydroxyl radical generated by 20 mU/$m\ell$ glucose oxidase with SED or SEE for 4 hr. The addition of 100$\mu\textrm{g}$/$m\ell$ SED in culture medium showed good protection from glucose oxidase (GO)-mediated cytotoxicity of hepatocytes, showing approximately equivalent to control. When the hepatocytes were incubated with 100 $\mu\textrm{g}$/$m\ell$ SED or SEE only for 4 hr. the activities of cell-associated superoxide dismutase (SOD) and catalase were elevated up to 1.22 fold and 1.4 fold, respectively, compared to control. Further increase, 1.88fold in SOD activity or 1.64fold in catalase activity, was also observed when the hepatocytes were incubated with 100 units/$m\ell$ of commercial SOD or catalase for 4 hr. Moreover. the glucose oxidase-mediated cytotoxicity in cultured hepatocytes was generally reduced upon addition of lysate obtained from SED or SEE-stimulated hepatocytes in a dose-dependent manner. From these results, we suggest that, in cultured hepatocytes, RVS ethanol extract can efficiently reduce cytotoxicity induced by glucose oxidase and may increase the activity of cell-associated SOD and/or catalase, thereby preventing and/or scavenging superoxides and hydroxyl radicals in this experiment.

• Structural Engineering and Mechanics
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• v.32 no.3
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• pp.383-398
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• 2009

Applying nonlinear statistical analysis methods in estimating the performance of structures in earthquakes is strongly considered these days. This is due to the methods' simplicity, timely lower cost and reliable estimation in seismic responses in comparison with time-history nonlinear dynamic analysis. Among nonlinear methods, simplified to be incorporated in the future guidelines, Modal Pushover Analysis, known by the abbreviated name of MPA, simply models nonlinear behavior of structures; and presents a very proper estimation of nonlinear dynamic analysis using lateral load pattern appropriate to the mass. Mostly, two kinds of connecting joints, 'hinge' and 'rigid', are carried out in different type of steel structures. However, it should be highly considered that nominal hinge joints usually experience some percentages of fixity and nominal rigid connections do not employ totally rigid. Therefore, concerning the importance of these structures and the significant flexibility effect of connections on force distribution and elements deformation, these connections can be considered as semi-rigid with various percentages of fixity. Since it seems, the application and implementation of MPA method has not been studied on moment-resistant steel frames with semi rigid connections, this research focuses on this topic and issue. In this regard several rigid and semi-rigid steel bending frames with different percentages of fixity are selected. The structural design is performed based on weak beam and strong column. Followed by that, the MPA method is used as an approximated method and Nonlinear Response History Analysis (NL-RHA) as the exact one. Studying the performance of semi-rigid frames in height shows that MPA technique offers reasonably reliable results in these frames. The methods accuracy seems to decrease, when the number of stories increases and does decrease in correlation with the semi-rigidity percentages. This generally implies that the method can be used as a proper device in seismic estimation of different types of low and mid-rise buildings with semi-rigid connections.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.3
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• pp.29-38
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• 2016

There have been only a few studies focused on the stabilization of metal (loid)s in anaerobic soils such as paddy soils. In this study, laboratory-scale column tests were conducted to artificially manipulate anoxic conditions in submerged paddy fields and we observed the release behavior of As, Cd, Pb, and Zn, as well as to examine the stabilization effect of steel refining slag (SRS) on the metal(loid)s. The leachate samples were collected and chemical parameters were monitored during the test period. Results suggest that anoxic conditions were developed during submersion, and that As or heavy metals (particularly Cd) fractions bound to ferrous (Fe) /manganese (Mn) oxides were easily dissociated. Moreover, As is also reduced by itself to a trivalent form with higher mobility in the reducing environment of rice paddy soil. However, it was also shown that SRS significantly decreased the dissolution of Zn, Pb, Cd, and As in the the leachates; their removal rates in the SRS-treated soil were 66 %, 45 %, 24 %, and 84 %, respectively, of those in the control soil.

• Journal of Ginseng Research
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• v.38 no.2
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• pp.116-122
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• 2014

Ginseng roots were extracted with aqueous methanol, and extracts were suspended in water and extracted successively with ethyl acetate and n-butanol. Column chromatography using the n-butanol fraction yielded four purified triol ginseng saponins: the ginsenosides Re, Rf, Rg2, and 20-gluco-Rf. The physicochemical, spectroscopic, and chromatographic characteristics of the ginsenosides were measured and compared with reports from the literature. For spectroscopic analysis, two-dimensional nuclear magnetic resonance (NMR) methods such as $^1H$-$^1H$ correlation spectroscopy, nuclear Overhauser effect spectroscopy, heteronuclear single quantum correlation, and heteronuclear multiple bond connectivity were employed to identify exact peak assignments. Some peak assignments for previously published $^1H$-and $^{13}C$-NMR spectra were found to be inaccurate. This study reports the complete NMR assignment of 20-gluco-Rf for the first time.

• Journal of the Korean Chemical Society
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• v.39 no.2
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• pp.94-102
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• 1995

S-Hydroxypropyl(PH) ${\beta}$-cyclodextrin(hydrophilic), dialkyl(DA)-cyclodextrin(hydrophobic), trifluoroacetyl(TA) ${\gamma}$-cyclodextrin(intermediate) stationary phases were used for gas chromatographic separation of racemic alcohols and their derivatives. All the alcohols used for this experiment were derivatived by using trifluoro acetic anhydride, acetic anhydride, or trichloro acetic anhydride. It is apparent that the enantioselectivity of the enantiomeric pairs was very dependent on the type of acylation reagent. The best experimental condition of optical resolution of the alcohols and their derivatives was different on the polarity of the solute molecules. The chiral separation was also studied depending on temperature, polarity of the column, and hydrogen bonding ability and steric effect between the alchols and CD stationary phase. The chiral recognition mechanism is dependent not upon the kinds of the chiral stationay phases but upon the derivatization of the racemic alchols.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1745-1750
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• 2013

A novel green aqueous mobile phase modified with room temperature ionic liquids (RTILs) was employed in the absence of volatile organic solvents or ion-pairing reagents to analyze thiamine, a very polar compound, by reverse phase high performance liquid chromatography (RP-HPLC). Due to its strongly hydrophilic nature, thiamine was eluted near the column dead time ($t_0$) using a mobile phase without adding RTILs or ion-pairing reagents, even if a 100% aqueous mobile phase, which has weak elution power under reverse phase conditions, was used. Thus, 1-ethyl-3-methyl-imidazolium hexafluorophosphate ([EMIM][$PF_6$]), which has the strongest chaotropic effect, was selected as a mobile phase additive to improve retention and avoid baseline disturbances at $t_0$. Various mobile phase parameters such as cation moiety, chaotropic anion moiety, pH and concentration of RTILs were optimized to determine thiamine at the proper retention time. Method validation was performed to assess linearity, intra- and inter-day accuracy and precision, recovery and repeatability; all results were found to be satisfactory. The developed method was also compared to the current official United States Pharmacopoeia (USP) and Korean Pharmacopoeia (KP) methods using an organic mobile phase containing an ionpairing reagent by means of evaluating various chromatographic parameters such as the capacity factor, theoretical plate number, peak asymmetry and tailing factor. The results indicated that the proposed method exhibited better efficiency of thiamine analysis than the official methods, and it was successfully applied to quantify thiamine in pharmaceutical preparations.

• Korean Journal of Medicinal Crop Science
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• v.27 no.6
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• pp.419-426
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• 2019

Background: This study aimed to identify antioxidant compounds from the seeds of Dolichos lablab L. by bioassay-guided isolation and recrystallization. Methods and Results: The water layer of D. lablab L. seed extract inhibits intracellular reactive oxygen species (ROS) expressing the 2',7'-dichlorofluorescein diacetate (DCF-DA), Cu/Zn superoxide dismutase (SOD) and catalase genes, as determined by quantitative real-time PCR (qRT-PCR). Two compounds were purified from the water layer of the seeds of D. lablab L. using column chromatography and prep-high performance liquid chromatography (HPLC). Using nuclear magnetic resonance (NMR) and electrospray Ionization mass spectrometry (ESI-MS), their chemical structures were identified as 5-[(2-acetyl-2,3-dihydro-1H-indazol-1-yl)carbonyl]-4,5-dihydro-3H-furan-2-one (C₁₄H₁₄N₂O₄) and stachyose. Conclusions: Two active antioxidant compounds were purified from the seed extract of D. lablab L. seed extract and the structures of these compounds were identified as C₁₄H₁₄O₄N₂ and stachyose.

• Journal of Korean Society on Water Environment
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• v.35 no.6
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• pp.459-469
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• 2019

The ozonation of sulfamethoxazole (SMX) was performed at 20℃ using a pilot scale countercurrent bubble column reactor. Ozonation systems were combined with UV irradiation and TiO₂ addition. As the oxidation reaction proceeded in each treatment system, the pH of the sample decreased and in the O₃/UV/TiO₂ system, the pH change was the largest from 4.54 to 2.02. Under these experimental conditions, the scavenger impact of carbonate is negligible. The highest COD and TOC removal rate was observed in the O₃/UV/TiO₂ system due to the UV irradiation and the photocatalytic effect of TiO₂. Also, the highest mineralization ratio(ε) value is 0.2 in the O₃/UV/TiO₂ system, which means theoxidation capacity of the systems. The highest SMX degradation rate constants calculated by COD and TOC values (COD and TOC) were 2.15 × 10^-4 sec^-1 and 1.00 × 10^-4 sec^-1 in the O₃/UV/TiO₂ system, respectively. The activation energy (E_a) of ozone treatment follows the Arrhenius law. It was calculated based on _COD and _TOC. Each activation energy decreased in order of single O₃> O₃/TiO₂> O₃/UV > O₃/UV/TiO₂ system. The result showed that ΔH^≠ is more effective than ΔS^≠ in each SMX ozontaionsystem, that is characteristic of the common oxidation reaction.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.108-116
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• 2017

In this study, the prototype structure of seismically designed steel moment frame was analyzed statically and dynamically in order to demonstrate the applicability of energy-based approximate analysis with the dynamic effect of sudden column loss in the evaluation of the collapse resistance and a method for assessing the sensitivity to progressive collapse was proposed. For the purpose of comparing the structural behavior of buildings with different structural systems, the sensitivity of the structure to the sudden removal of vertical members can be used as a significant measure. The energy-based approximate analysis prediction for the prototype structure considered in the study showed good agreement with the dynamic analysis result. In the sensitivity evaluation, the structural robustness index that indicates the ability of a structure to resist collapse induced by abnormal loads was used. It was confirmed that the proposed methods can be used conveniently and rationally in progressive collapse analysis and design.