• Membrane Journal
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• v.22 no.3
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• pp.171-177
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• 2012

Effect of humic acid (HA), photo-oxidation and adsorption with periodic $N_2$ back-flushing was investigated in hybrid process of ceramic ultrafiltration and photocatalyst for drinking water treatment. It was compared and investigated with the previous result at water back-flushing in viewpoints of membrane fouling resistance ($R_f$), permeate flux (J), and total permeate volume ($V_T$). As decreasing HA, $R_f$ decreased dramatically and J increased, and finally $V_T$ was the highest at HA 2 mg/L. As HA concentration increased from 2 to 10 mg/L, the membrane fouling resistance after 180 mins' operation ($R_{f,180}$) improved 0.8 times more than that of water back-flushing. Therefore, HA concentration should affect on the membrane fouling at $N_2$ back-flushing than water back-flushing. Turbidity treatment efficiencies were almost constant independent of HA concentration, but HA treatment efficiency was the maximum at HA 2 mg/L. This means that adsorption and photo-oxidation of photocatalyst beads could removed HA at HA 2 mg/L, but it was not enough at 4 mg/L. Beyond HA 6 mg/L, UF could effectively treat HA by thick cake layer on membrane surface and severe inner membrane fouling.

• Journal of the Korea Organic Resources Recycling Association
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• v.22 no.3
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• pp.23-32
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• 2014

Recently, it is increase in the processing of organic waste using anaerobic digestion. Therefore, the studies on the processing method for increasing the anaerobic digestion waste water. But it is very difficult to solid-liquid separation, because the characteristics of anaerobic digestion waste water. So this study evaluate solid-liquid separation efficiency of anaerobic digestion sludge using CST(Capillary Suction Time), TTF(Time to Filter). To address this problem, a membrane filter press of the lab scale was produced and the anaerobic digestion wastewater was applied to it. Polymer coagulants were found to be most suitable 7192PLUS and 1T60, It is necessary to minimum injection concentration is 7192PLUS (200 mg/L), 1T60 (100 mg/L). To evaluate dehydration efficiency, it was measured the moisture content of the dehydrated cake and suspended solids of decanted water. As a result, showed that a high removal efficiency of 97.4% when the solid-liquid separation using the membrane filter press. And the moisture content of the dehydrated cake was less than 65%.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.7
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• pp.752-756
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• 2006

The independent anoxic reactor was introduced in biological aerated filters as the regulation of water quality requirement, especially total nitrogen, had been strengthened. The process studied in this work was upflow $Biobead^{(R)}$ process which was used commercial invented for removal of organic materials and nitrification. For the purpose of evaluating the independent anoxic reactor, PCR-DGGE, of the molecular biological methods, was performed. Two types of nitrite reductase genes were selected. One is nirS represented cytocrome $cd_1$ nitrite reductase gene and the other is nirK represented Cu-containing nitrite reductase gene. Denitrifier community in the independent anoxic reactor was analyzed with PCR-DGGE using these two denitrifying functional genes. As the result of the PCR, only nirS gene was detected between nirS and nirK. With the result of the DGGE, specific bands became strong, as the operating days were longer, nitrate loading rate was increased. otherwise those of the initial activated sludge showed various bands. In the consequence of the sequence of DGGE bands, various denitrifiers were sequenced in the initial activated sludge, while specific denitrifiers like alcaligenes faecalis were predominant in the anoxic reactor. Consequently, introduction of the independent anoxic reactor made it possible to achieve 96% denitrification efficiency, and was proper for the modification of BAF process.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.2
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• pp.158-162
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• 2005

The objective of this study was to assess the assimilable organic carbon (AOC) in processing water, a measurement of biostability, at several stages of a full-scale nanofiltration (NF) water treatment plant. The NF membrane plant investigated was a $45,400\;m^3$/day (12 mgd) water softening facility at Plantation City in southern Florida, which utilized an organic rich groundwater (dissolved organic carbon (DOC) = 17.6 mg/L) originated from a surficial aquifer. The average AOC concentration of raw feed water was estimated at 158 g/L acetate-C. After pretreatment(acid and antiscalant addition), AOC levels increased by 12.7%, suggesting that pretreatment chemicals used to control scaling may deteriorate feed water biostability. The results also demonstrated that nanofiltration was capable of effectively removing 63.4% of AOC and 94.8% of DOC from the raw water. AOC rejection in stage 1 (${\approx}\;68%$) was slightly higher than that of stage 2 (${\approx}\;58%$) indicating that AOC was removed less at the solution environment (i.e. low pH, high ionic strength and high hardness), which was often created in the $2^{nd}$ stage of full-scale membrane plants due to pretreatment (acid addition) and high recovery operation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.2
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• pp.180-185
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• 1999

Rotating Biological Contactor (RBC) was tested for the treatment of artificial rearing water in n simulated aquaculture system. Performance of RBC on the removal of TAN and COD was evaluated by controlling hydraulic residence time (HRT). As HRT of RBC was increased, TAN removal rate ana removal efficiency of RBC and TAN concentration of rearing water were increased, but COD removal rate was decreased. Total alkalinity consumption rate was increased by increasing HRT of RBC. Ratio between total alkalinity consumption rate and TAN removal rate was 7.73. HRT for maintaining lowest TAN and COD concentration of artificial rearing water was 14,6 minutes and at that condition TAN and COD concentration of the water was 1.28 and $5.59 g/m^3$, respectively.

• Journal of the Korean Association of Geographic Information Studies
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• v.15 no.1
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• pp.64-75
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• 2012

To predict the future distribution of forest vegetation, the present forest stand distributions of South Korea were represented by multinomial logit model with the following environmental variables: summer average precipitation, the coldest month average temperature, elevation, degree of base saturation, and soil organic matter. The future forest community was predicted by applying the MIROC3.2 hires A1B scenario. The future climate data were downscaled by statistically method. The coldest month average temperature increased $4.4^{\circ}C$, $6.0^{\circ}C$, and $9.4^{\circ}C$, and 3 months average precipitation changed -1.2%, 5.7%, and 5.3% for 2020s, 2050s, and 2080s respectively. For the projected summer precipitation and the coldest temperature, the future deciduous and mixed forests in the study area increased 56.9% and 8.3% and the coniferous forest decreased 11.2% in 2080s based on present.

• Journal of the Korean GEO-environmental Society
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• v.9 no.3
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• pp.35-43
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• 2008

This study was carried out to estimate the performance of modified sequencing batch reactor (SBR) process by the application of SBR process for small advanced wastewater treatment plant. Organic, nitrogen and phosphorus were able to remove in the unit reactor by SBR process and it would be able to select the suitable operation method. The plant was operated to achieve high performance with influent control, optimum anoxic/oxic condition using intermediate aeration method, and solid (sludge) /liquid (effluent) separation by modified decanter. The optimum operating mode was 3Cycles a day and intermediate input and aeration. Under these conditions, the treatment efficiencies were good with 60% of designed flow rate and low influent quality. When the influent concentrations of BOD and CODMn were 120.4 mg/L and 95.7 mg/L, respectively. The effluent concentrations of BOD and CODMn were 6.8 mg/L and 11.0 mg/L, respectively. The average removal efficiencies of BOD and CODMn were 94.4% and 88.5%, respectively. The removal efficiencies of T-N and T-P were 69.6% and 73.6%, respectively when the average T-N and T-P concentrations were 32.2mg/L and 4.65mg/L, respectively. The T-N and T-P removal efficiencies were slightly decreased to 58.8% and 68.5%, respectively in the winter season but its were also stable efficiencies. BOD, T-N and T-P were removed by 90%. 67% and 46% respectively in the first anoxic/oxic condition, in addition to T-P was removed by 70% in the second anoxic/oxic condition. From the results, modified sequencing batch reactor (SBR) process is suitable for small advanced wastewater treatment.

• Journal of the Korean Chemical Society
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• v.53 no.5
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• pp.553-559
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• 2009

One of zeolitic imidazolate framework materials (ZIF), ZIF-8, has been synthesized with microwave irradiation and conventional electric heating at $140{\sim}180^{\circ}C}$. ZIFs are porous crystalline materials and are similar to metal organic framework (MOF) materials because both ZIFs and MOFs are composed of both organic and metallic components. ZIFs are very stable and similar to zeolites because ZIFs have tetrahedral networks. ZIF-8, with a decreased crystal size, can be synthesized rapidly with microwave irradiation. The microwave synthesis of ZIF-8 is completed in 4 h at $140{^{\circ}C}$ and the reaction time is decreased by about 5 times compared with the conventional electric heating. The ZIF-8 obtained by microwave heating has larger surface area and micropore volume compared with the ZIF-8 synthesized with conventional electric heating. It can be confirmed that ZIF-8s show type-I adsorption isotherms, explaining the microporosity of the ZIF-8s. Based on FTIR and TGA results, it can be understood that the ZIF-8s have similar bonding and thermal characteristics irrespective of heating methods such as microwave and conventional heating.

• Membrane Journal
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• v.21 no.4
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• pp.360-366
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• 2011

The effect of cross-flow velocity and transmembrane pressure (TMP) on membrane fouling was observed from pilot-scale operation of thermophilic anaerobic membrane bioreactor (AnMBR) treating food waste leachate. It was found that fouling rate was reduced significantly as cross-flow velocity increased at constant TMP mode of operation while this effectiveness was more pronounced at lower TMP. Higher TMP resulted in less permeable fouling layer possibly due to compressibility of foulant material on membrane surface. Particle sizes of membrane concentrate ranged from 10 to $100{\mu}m$, implying that shear-induced diffusion enhance back transport of these particle sizes away from the membrane effectively. From the continuous operation of AnMBR, it was confirmed that shear rate played an important role in the reduction of membrane fouling. Membrane autopsy works at the end of operation of AnMBR showed clearly that both organic and inorganic fouling were significant on membrane surface. Surface shear by cross-flow velocity was expected to be less effective to remove irreversible fouling which can be mainly caused by the adsorption of organic colloidal materials into membrane pores.

• Conservation Science in Museum
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• v.4
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• pp.23-32
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• 2003

As the kettle excavated from a site in Hwangnam-dong, Gyeongju was presumed to have been used as a melting crucible in a glass production workplace, we decided to prove its usage by scientific analysis. First, we performed conservation treatment to find the original status of the kettle, and then SEM-EDS and XRD analysis of the five corrosions created on the surface of the kettle. The fragment of the spout, which played a crucial role for the kettle to be considered as a melting crucible, was discovered during the conservation treatment. So the mouth rim of the kettle was restored to perfection. When we observed the microstructure of the metal sample, it was proved to be cast iron gradually cooled without heat treatment. In the corrosion products, the main components were Fe and O and other components such as P, Si, Ca, and S were found. The main compounds were quartz, vivianite, goetheite, akaganite, lepidocrocite, hematite, etc. Although these components were used as raw materials for making glass, these were found not in the melting status but mere raw materials. This can be an evidence to show these site where the kettle was excavated had been a glass production workplace. However, it is not sure that the kettle was used as a melting crucible. Moreover, if we consider the organic mold and sand clay accumulated in the well site when the kettle was excavated at first, we can see this as a formative factor of the corrosions of the kettle. Therefore, we concluded that the kettle is a typical cast iron and was not used as a melting crucible of glass.