• Asian Journal of Atmospheric Environment
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• v.7 no.3
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• pp.129-138
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• 2013

The water uptake by fine aerosol in the atmosphere has been investigated at Gosan, Korea during ABC-EAREX 2005. The concentration of inorganic ion and carbon components, size distribution, and light scattering coefficients in normal and dry conditions were simultaneously measured for $PM_{2.5}$ by using a parallel integrated monitoring system. The result of this study shows that ambient fine particles collected at Gosan were dominated by water-soluble ionic species (35%) and carbonaceous materials (18%). In addition, it shows the large growth of aerosol in the droplet mode when RH is higher than 70%. Size distribution of the particulate surface area in a wider size range ($0.07-17{\mu}m$) shows that the elevation of RH make ambient aerosol grow to be the droplet mode one around $0.6{\mu}m$ or the coarse mode one, larger than $2.5{\mu}m$. Hygroscopic factor data calculated from the ratio of aerosol scattering coefficients at a given ambient RH and a reference RH (25%) show that water uptake began at the intermediate RH range, from 40% to 60%, with the average hygroscopic factor of 1.10 for 40% RH, 1.11 for 50% RH, and 1.17 for 60% RH, respectively. Finally, average chemical composition and the corresponding growth curves were analyzed in order to investigate the relationship between carbonaceous material fraction and hygroscopicity. As a result, the aerosol growth curve shows that inorganic salts such as sulphate and nitrate as well as carbonaceous materials including OC largely contribute to the aerosol water uptake.

• The Journal of the Korea Contents Association
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• v.16 no.5
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• pp.660-667
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• 2016

Conventional decontamination methods utilize water-based systems, which generate high amounts of secondary wastes. Herein, we describe an environmentally benign decontamination method using liquid and supercritical $CO_2$. The use of $CO_2$ as a solvent affords effective waste reduction by its ability to be recycled, thereby leaving be hind only the contaminants upon its evaporation. In this study, a $CO_2$ solution process was assessed using t-salen(t-butylsalen), DC18C6 (dicyclohexano-18Crown6), 8-HQN(8-hydroxyquinoline), NEt4PFOSA(perfluoro-1-octanesulfonic acid tetra-ethyl ammonium salt), and NEt4PFOA(pentadecafluorooctanoic acid ammonium salt) to extract spiked radioactive contaminants(Nb,Zr,Co,Sr) from an inert sample matrix, namely filter paper. With the static extraction method, Sr was extracted with a maximum extraction rate of 97%, and Nb was extracted with a maximum extraction rate of 75%. Additionally, we were also able to extract Co and Zr with maximum extract ion ratesof 73% and 64%, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.5
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• pp.378-381
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• 2009

The purpose of this research is the evaluation of removal efficiency of THMFP in BAC. The changes of four types of THMFP and total THMFP were examined in the influent and effluent of BAC filter from March to December in 2008. It turned out that the amounts of brominated THMFP were obviously higher in winter and autumn compared to the spring and summer, which also resulted in an increase of the total-THMFP levels during winter and autumn. In addition, long-term running of BAC filter shows the good removal function of chloroform formation potential, but not brominated THMFP; with further bromination, this function was declined, as it shows the formation of bromoform in BAC filter during October and December. These results were caused by changing of the proportion of $Br^-$/DOC.

• Journal of the Korean Chemical Society
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• v.30 no.3
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• pp.265-272
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• 1986

Kinetic studies for the methanolysis of tert-butyl halides (t-BuCl, t-BuBr, t-BuI) were carried out in MeOH-1,1,2,2-tetrachloroethane mixtures. The solvatochromic comparison method was used with six indicators to analyze solvent effects on the ionizations of tert-butyl halides. It was shown that the cooperative effect of solvent polarity-polarizability was the most important factor influenced on the methanolysis rates of tert-butyl halides, but the electrophilic assistance for halide leaving group and the nucleophilic assistance for tert-butylium ion were considerably influential, too. And it was found that the electrophilic assistance caused by hydrogen bonding and the nucleophilic assistance for carbon center were stronger for more basic leaving group ($I^-) and more polarizable leaving group(t-BuCl

• Journal of Environmental Science International
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• v.22 no.9
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• pp.1153-1160
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• 2013

While a range of natural organic matter (NOM) types can generate high levels of disinfection by-products (DBPs) after chlorination, there is little understanding of which specific compounds act as precursors. Use of eight model compounds allows linking of explicit properties to treatability and DBP formation potential (DBPFP). The removal of model compounds by various treatment processes and their haloacetic acid formation potential (HAAFP) before and after treatment were recorded. The model compounds comprised a range of hydrophobic (HPO) and hydrophilic (HPI) neutral and anionic compounds. On the treatment processes, an ozone oxidation process was moderate for control of model compounds, while the HPO-neutral compound was most treatable with activated carbon process. Biodegradation was successful in removing amino acids, while coagulation and ion exchange process had little effect on neutral molecules. Although compared with the HPO compounds the HPI compounds had low HAAFP the ozone oxidation and biodegradation were capable of increasing their HAAFP. In situations where neutral or HPI molecules have high DBPFP additional treatments may be required to remove recalcitrant NOM and control DBPs.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.1
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• pp.143-151
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• 2001

A marine bacterium producing carotenoid was isolated from the Yosu coastal area of South Korea, which was recorded as MCK-1. It was identified as Erythrobacter sp. Optimium conditions of marine carotenoid fermentation from Erythrobacter sp. were pH 6.0, a temperature of $25^{\circ}C$, 16 mM mannitol as a carbon source, 0.5% tryptone as a nitrogen source, 0.1 mM $Fe^{+2}$ ion as a mineral source and 1$\mu$M of cyanocobalamine as a growth factor in a jar-fermentor. Erythrobacter sp. was produced 351.27 mg/100mL of the marine carotenoid in these optimum conditions. This marine carotenoid was composed of 4 different conpounds, like as notoxanthin (61.4%), can thaxanthin (24.6%), fucoxanthin (8.2%), and zeaxanthin (5.8%). Physiological properties including antibacterial activity, cytotoxic effect, antioxidative effect and free radical scavenging activity were characterized with crude carotenoid. Carotenoid exhibited no antibacterial activity against E. coli and lactobacillus bulgaricus, but showed cytotoxic effect against cancer cells such as HepG2 (Hepatocellular carcinoma, human, ATCC HB-8065) and HeLa (Cervical carcinoma, human, ATCC CCL-2) cells. The impediment ratios for HepG2 and HeLa cell were 37.14% and 33.78%, respectively. This carotenoid expressed a strong antioxidative effect (77%) against CCL-13 5 $\mu\textrm{g}$/mL and 50 $\mu\textrm{g}$/mL crude carotenoid, respectively.

• Journal of Environmental Science International
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• v.25 no.11
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• pp.1467-1474
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• 2016

In response to the water shortage problem, continued attempts are being made to secure consistent and reliable water sources. Among various solutions to this problem, wastewater effluent is an easy way to secure the necessary supply, since its annual output is consistent. Furthermore, wastewater effluent has the advantage of being able to serve various purposes, such as cleaning, sprinkling, landscaping, river management, irrigation, and industrial applications. Therefore, this study presents the possible use of reclaimed industrial wastewater treated with Birm filters and a UF membrane, along with an analysis on membrane fouling. The preprocessing stage, part of the reclamation process, used Birm filters to minimize membrane fouling. Since this study did not consider heavy metal levels in the treated water, the analyses did not include the criterion for irrigation water quality. However, the wastewater reclaimed by using Birm filters and a UF membrane met every other requirement for reclaimed water quality standards. This indicated that the treated water could be used for cleaning, channel flow for maintenance, recreational purposes, and industrial applications. The analysis on the fouling of the Birm filter and UF membrane required the study of the composition and recovery rate of the membrane. According to SEM and EDX analyses of the UF membrane, carbon and oxygen ion composition amounted to approximately 57%, whereas inorganic matter was not detected. Furthermore, the difference in the recovery rates of the distressed membrane between acidic and alkaline cleaning was more than ~78%, which indicated that organic rather than inorganic matter contributed to membrane fouling.

• Proceedings of the Korean Environmental Health Society Conference
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• 2002.04a
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• pp.23-25
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• 2002

This study was conducted to understand characteristics of wastewater which is discharged from small-scale dyehouse located in Seoul downtown area and to Find the appliable treatment method on the spot. The results of this study were summarized as followings. 1. The method which is used at present is mostly flocculation by coagulant or fenton oxidation. But the treatment efficiency of them are not good. 2. The results of fenton oxidation experiment demonstrated that treatment efficiency of COD was limited, which showed the need of the additional process or the improvement of existing treatment method, while the color was reduced considerably in optimal condition. 3. The optimal condition of fenton oxidation are as followings. -Feasible pH was in the 3∼4 regardless of the kinds of iron ions, But the fluctuation of treatment efficiency with the change of pH was small - The mass ratio of H$_2$O/CODcr was used to evaluate the parameter of H$_2$O$_2$ The optimal range of this was in 0.7∼1,3 and it was observed that the ratio got higher as the quality got worse. -For iron ion, FeCl$_2$4H$_2$O turned out to be more effective for removal of color compared with was compared FeSO$_4$7H$_2$Oin. the mass ratio of Fe/H$_2$O$_2$ of 2.3∼2.8 for of FeSO$_4$7H$_2$O and 1.6∼1.8 for FeCl$_2$4H$_2$O resulted in good treatment efficiencies. 4. With adsorption process applied before fenton oxidation in order to treat the high concentration wastewater, the treatment efficiency increased by 61％ in CODcr, 55％ in color. and if the power activated carbon is injected in more than 2500mg/$\ell$, the wastewater can be treated within the effluent quality criteria.

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.489-496
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• 2018

Fuel cells are seen as eco-friendly energy resources that convert chemical energy into electrical energy. However, proton exchange membrane fuel cells (PEMFCs) have problems such as the use of expensive platinum catalysts for the reduction of conductivity under high temperature humidification conditions. Thus, an anion exchange membrane fuel cell (AEMFC) is attracting a great attention. Anion exchange fuel cells use non - Pt catalysts and have the advantage of better efficiency because of the lower activation energy of the oxygen reduction reaction. However, there are various problems to be solved including problems such as the electrode damage and reduction of ion conductivity by being exposed to the carbon dioxide. Therefore, this mini review proposes various solutions for different problems of anion exchange fuel cells through a wide range of research papers.

• KSBB Journal
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• v.8 no.2
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• pp.164-171
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• 1993

The production of extracellular polysaccharide by Methylomonas mucosa (NRRL B-5696) was investigated. The microorganism uses methanol as the carbon source for their growth and produces exopolysaccharides. The productivity of exopolysaccharides was investigated under various culture modes: batch, fed-batch and continuous culture. In flask culture the growth of cell mass and the production of polysaccharide were inhibited at above 1% (v/v) methanol. At 1%(v/v) methanol maximum specific growth rate was obtained. As C/N ratio (g methanol/g ammonium sulfate) increased, polysaccharide production increased and cells mass decreased. Magnesium ion was also found to be essential for the polysaccharide production. In batch culture the production of polysaccharides was more affected by the specific growth rate than the cell concentration. In fed-batch culture the concentration of polysaccharide was 4 times higher than that of batch culture, but the yield was lower. The productivity of fed-batch with continuous feeding was higher than that of batch or fed-batch with intermittent feeding. This is due to no methanol limitation or inhibition that used to occur in fed-batch culture with intermittent feeding. In continuous culture pure oxygen was supplied to avoid the oxygen limitation. As the dilution rate in- creased up to 0.21 h-1, the yield and productivity increased. The solution viscosity of the produced polysaccharide obtained from above increased exponentially with the concentration of polysaccharide.