• Journal of the Korean GEO-environmental Society
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• v.15 no.9
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• pp.5-12
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• 2014

Anaerobic digestion was investigated for the stabilization of sludge, decrease of volatile solids, production of biogas for wastewater sludge. In this study, total solids and volatile solids, elemental analysis were conducted to determine characteristics of various types of sludges and investigate the feasibility of biogas production of Municipal Wastewater Sludge (MWS), Industrial Wastewater Sludge (IWS), mixed sludge (Mix), and Municipal Wastewater Sludg Cake (MWSC). Total solids, volatile solids, and C/N ratio were determined in the range of 11.2~20.6 %, 62.1~83.1 % of TS and 4.96~8.33 %. Using the biochemical methane potential (BMP test), mixed sludge and wastewater sludge finished the methane production within approximately 20 day and 16~17 day. Sludge cake finished within 10 day. Mixed sludge produced 395.5 mL $CH_4$ per g of Volatile Solid (VS) and resulted in the highest methane production. For carbon dioxide production, five sludges had similar value of accumulated carbon dioxide production except for sludge cake.

• Atmosphere
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• v.27 no.1
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• pp.41-54
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• 2017

Organic carbon (OC) and elemental carbon (EC) in $PM_{2.5}$ were measured using Sunset OC/EC Field Analyzer at Seoul Hwangsa Monitoring Center from March to April, 2016. The mean concentrations of OC and EC during the entire period were $4.4{\pm}2.0{\mu}gC\;m^{-3}$ and $1.4{\pm}0.6{\mu}gC\;m^{-3}$, respectively. OC/EC ratio was $3.4{\pm}1.0$. The average concentrations of $PM_{10}$ and $PM_{2.5}$ were $57.4{\pm}25.9$ and $39.7{\pm}19.8{\mu}g\;m^{-3}$, respectively, which were detected by an optical particle counter. The OC and EC peaks were observed in the morning, which were impacted by vehicle emission, however, their diurnal variations were not noticeable. This is determined to be contributed by the long-range transported OC or secondary formation via photochemical reaction by volatile organic compounds at afternoon. A conditional probability function (CPF) model was used to identify the local source of pollution. High concentrations of $PM_{10}$ and $PM_{2.5}$ were observed from the westerly wind, regardless of wind speed. When wind velocity was high, a mixing plume of dust and pollution during long-range transport from China in spring was observed. In contrast, pollution in low wind velocity was from local source, regardless of direction. To know the effect of long-range transport on pollution, a concentration weighted trajectory (CWT) model was analyzed based on a potential source contribution function (PSCF) model in which 75 percentiles high concentration was picked out for CWT analysis. $PM_{10}$, $PM_{2.5}$, OC, and EC were dominantly contributed from China in spring, and EC results were similar in both PSCF and CWT. In conclusion, Seoul air quality in spring was mainly affected by a mixture of local pollution and anthropogenic pollutants originated in China than the Asian dust.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.3
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• pp.55-61
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• 2018

This study evaluated if the selected samples meets the Solid Refuse Fuel quality criteria in Korea. Biomass and plastic wastes generated in D City were mixed in diverse ratio. When the biomass content was about 40%, the moisture content was close to the SRF criteria and was measured to be 9.8%. The ash contents were analyzed up to 4.19%, and the lower calorific values based on Steuer, Dulong Equation and Bomb Calorimeter were at least 4,851, 4,181 and 3,847 kcal/kg, respectively. As a result of the elemental analysis, sulfur and chloride content were measured up to 0.05%. Those values satisfied the SRF criteria. Also, heavy metals(Hg, Cd, Pb, As) were analyzed to be below the SRF criteria. This makes it possible to use efficiently the wood byproducts abandoned in the woods, and the physical properties of wood being weak to moisture can be supplemented with plastics. Consequently, if plastic and biomass were well mixed and made into SRF, it would overcome the problem of shortening the life span of incineration facilities due to the high temperature of plastic wastes in the incinerator.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.1
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• pp.67-81
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• 2016

In order to examine the variation characteristics of chemical compositions in accordance with the different meteorological conditions, $PM_{10}$ and $PM_{2.5}$ were collected at Gosan site of Jeju Island in 2014, and then their ionic and elemental species were analyzed. The concentrations of nss-$SO{_4}^{2-}$ and $NH_4{^+}$ were respectively 4.3 and 3.3 times higher in fine particle mode ($PM_{2.5}$) compared to coarse particle mode ($PM_{10-2.5}$), however $NO_3{^-}$ concentration was 1.6 times higher in coarse mode compared to fine particle mode. During Asian dust days, the concentrations of nss-$Ca^{2+}$ and $NO_3{^-}$ increased highly as 7.7 and 4.5 times in coarse particle mode, and 3.0 and 4.9 times higher in fine particles, respectively. Especially, the concentrations of the crustal species (Al, Fe, Ca, K, Mn, Ba, Sr, etc.) indicated a noticeable increase during the Asian dust days. For the haze days, the concentrations of secondary pollutants increased 2.2~2.7 and 2.9~6.0 times in coarse and fine particles, respectively, and they were 0.8~1.1 and 1.8~2.4 times, respectively, during the mist days. The aerosols were acidified largely by sulfuric and nitric acids, and neutralized mainly by ammonia in fine particle mode during the haze days, but neutralized by calcium carbonate in coarse particle mode during the Asian dust days. The clustered back trajectory analysis showed that the concentrations of nss-$SO{_4}^{2-}$, $NO_3{^-}$, and $NH_4{^+}$ were relatively high when the inflow pathway of air mass was from the southern part of China.

• Asian Journal of Atmospheric Environment
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• v.6 no.4
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• pp.288-303
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• 2012

In this study, real time measurements of particle number size distribution in urban Gwangju, coastal Taean, and industrial Yeosu in Korea were conducted in 2008 to understand the occurrence of ultrafine particle (UFP) (<100 nm) events, the variation of its concentration among different sampling sites, and UFP formation pathways. Also, to investigate seasonal and long-term variation of the UFP number concentration, data were collected for the period of 5 years (2007, 2008, 2010, 2011, and 2012) in urban Gwangju. Photochemical and combustion events were found to be responsible for the formation of UFP in the urban Gwangju site, whereas only photochemical event led to the formation of UFP in the coastal Taean site. The highest UFP concentration was found in industrial Yeosu (the average UFP number fractions were 79, 59 and 58% in Yeosu, Gwangju, and Taean, respectively), suggesting that high amount of gas pollutants (e.g., $NO_2$, $SO_2$, and volatile organic carbon (VOC)) emitted from industries and their photochemical reaction contributed for the elevated UFP concentration in the industrial Yeosu site. The UFP fraction also showed a seasonal variation with the peak value in spring (61.5, 54.5, 50.5, and 40.7% in spring, fall, summer, and winter, respectively) at urban Gwangju. Annual average UFP number concentrations in urban Gwangju were $5.53{\times}10^3\;cm^{-3}$, $4.68{\times}10^3\;cm^{-3}$, $5.32{\times}10^3\;cm^{-3}$, $3.99{\times}10^3\;cm^{-3}$, and $2.16{\times}10^3\;cm^{-3}$ in the year 2007, 2008, 2010, 2011, and 2012, respectively. Comparison of the annual average UFP number concentration with urban sites in other countries showed that the UFP concentrations of the Korean sites were lower than those in other urban cities, probably due to lower source strength in the current site. TEM/EDS analysis for the size-selected UFPs showed that the UFPs were classified into various types having different chemical species. Carbonaceous particles were observed in both combustion (soot and organics) and photochemical events (sulfate and organics). In the photochemical event, an internal mixture of organic species and ammonium sulfate/bisulfate was identified. Also, internal mixtures of aged Na-rich and organic species, aged Ca-rich particles, and doughnut shaped K-containing particles with elemental composition of a strong C with minor O, S, and K-likely to be originated from biomass burning nearby agricultural area, were observed. In addition, fly ash particles were also observed in the combustion event, not in the photochemical event.

• Polymer(Korea)
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• v.30 no.1
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• pp.64-69
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• 2006

A series of dinuclear half-sandwich titanium complexes with aryloxy substituent at titanium$[(\eta^5-cyclopentadienyl)(aryloxy)TiCl_2]_2[(CH_2)_n]$ (n=3, n=6, n=9) have been successfully synthesized and their styrene polymerization properties have been investigated. All complexes are characterized by $^1H\;NMR,\;^{13}C\;NMR$, elemental analysis, and mass spectrometry. In order to examine the catalytic properties of the dinuclear complexes styrene polymerization has beer conducted in the presence of MMAO. It was found that (i) all the prepared complexes were very effective catalyst for the production of SPS (syndiotactic polystyrene), (ii) the complex with the longest bridge between the two active sites exhibited greatest catalytic activity among the three catalysts, but produced SPS with the smallest molecular weight, (iii) the activities of dinuclear half-titanocens with aryloxy substitution at titanium metal were greater than those of the chloride substituted compounds. These results indicate that not only the nature of the bridge between the two active sites but also the property of substituents at the metal exert a significant influence on the polymerization behaviors of the dinuclear half-titanocene.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.10
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• pp.1525-1530
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• 2005

The purpose of this study is to investigate anti-tumor activities, general composition, elemental composition and mineral contents of fermented liquid stem, root and fruit of Opuntia humifusa. In the general composition, the energy, crude protein, crude lipid and crude carbohydrate contents of fermented liquid stem were 86.21 Kcal, 0.92$\%$, 0.12$\%$, and 20.34$\%$, respectively. Fermented liquid fruit showed 65.32 Kcal, 1.04$\%$, 0.08$\%$, and 15.15$\%$. In mineral analysis, fermented liquid stem and fruit showed 1,800 and 388 mg of calcium per 100g. The ferrous concentrations of fermented liquid stem and fruit were 21 and 10 mg per 100 g, respectively. Methanol, ethanol and water extracts of nonfermented liquid stem and fruit did not inhibit the proliferation in human cervical cancer cells (Caski, SiHa and HaCaT), but the fermented liquid fruit showed the inhibition of Proliferation with dose-response manner in Caski and SiHa cells, but not HaCaT. Therefore, it suggests that fermented cactus may be used as one of potential adjuvant for the treatment of cervical carcinomas.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.6
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• pp.415-421
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• 2013

To increase specific surface property of activated carbon fiber(ACF), chemical activation(CA) using alkali metals and surface treatment(ST) using oxidant was widely used. The CA and ST process developed micro-pore on the surface of ACF by chemical reaction of the alkali metals and oxidative of oxidant, respectively. To improve the efficiency of CA process for developing micro-pores on the surface of ACF, the ST process was adopted as an pre-treatment method. After treatment of ST process, ACF properties was investigated depending on the ST pre-treatment process. FT-IR, TG and elemental analysis of the ACF are carried out, and an adsorption property of ACF was also evaluated using toluene(which in typical volatile organic matter). Once the single CA process is used, the surface area and adsorption capacity of ACF were increased from 1,483 to 1,988 $m^2/g$ and from 0.22 to 0.27 $g_{-Tol.}/g_{-ACF}$, respectively. On the other hands, once the ST and CA processes are used successively, the surface area and adsorption capacity of ACF are greatly increase(where the surface area is 2,743 $m^2/g$ and the adsorption capacity is 0.37 $g_{-Tol.}/g_{-ACF}$). It indicates that the combined process of ST and CA can improve the surface process properties of ACF.

• Analytical Science and Technology
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• v.13 no.2
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• pp.173-178
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• 2000

A new open-chain ligand containing two phenol groups, 1, 14-Bis (2-hydroxybenzyl)-2, 6, 9, 12-tetraazatetradecane(bsated) was synthesized as its tetrahydrochloride salt and characterized by elemental analysis, mass, infrared and NMR. Its proton dissociation constants ($logK^n{_H}$) and stability constants ($logK_{ML}$) toward $Co^{2+}$, $Ni^{2+}$, $Cu^{2+}$ and $Zn^{2+}$ were determined at $25^{\circ}C$ and 0.10M($KNO_3$) ionic strength in aqueous solution by potentiometry. The X-ray structure of its copper (II) complex [Cu(bsated)]$(ClO_4)_2$ was reported: Monoclinic space group $P2_1/n$, $a=17.856(4){\AA}$, $b=17.709(1){\AA}$, $c=8.539(2){\AA}$, $V=2700(2){\AA}$ with Z=4. Electrochemical studies of [Cu(bsated)]$(ClO_4)_2$ complex in dimethyl sulfoxide (DMSO) solution containing tetrabutylammonium perchlorate (supporting electrolyte) were carried out by cyclic voltammograms (CV) and normal pulse voltammetry (NPV).

• Analytical Science and Technology
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• v.8 no.1
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• pp.55-62
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• 1995

Tetradentate Schiff base cobalt(II) complexes such as $Co(II)_2-N$, N-bis(salicylidene)-m-phenylendiimine; [$Co(II)_2(SMPD)_2(H_2O)_4$] and $Co(II)_2-N$, N-bis(salicylidene)-p-phenylendiimine: [$Co(II)_2(SPPD)_2(H_2O)_4$], and oxygen adducted cobalt (III) complexes such as [$Co(III)_2O_2(SMPD)_2(Py)_2$] and [$Co(III)_2O_2(SPPD)_2(Py)_2$] in pyridine solutions were synthesized. It was identified that the oxygen adducted cobalt(III) complexes have hexacoordinated octahedral configuration with pyridine and oxygen from the measurement of elemental analysis, AA, IR spectra, and TGA. The redox processes were investigated for the oxygen adducted complexes in 0.1M TEAP-pyridine solution, using cyclic voltammetry on the glassy carbon electrode. The redox processes of oxygen adducted Co(III) complexes result in $$[Co(III)_2-O_2-CO(III)]\rightarrow^{e^-}[Co(III)-O_2-Co(II)]\rightarrow^{e^-}[Co(II)-O_2-Co(II)]\rightleftarrows^{e^-}[Co(II)+Co(II)+O_2{\cdot}^-]\rightleftarrows^{e^-}[Co(II)+Co(I)+O_2{\cdot}^-]\rightleftarrows^{e^-}[Co(I)+Co(I)+O_2{\cdot}^-]$$.