• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.2
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• pp.83-90
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• 2006

The NaCl contents of food waste composts made by various techniques known up to now were under the level of 1% by fresh weight basis. But these techniques has some problem that is environment pollution from treated water and high equipment cost. The application to agricultural land of food waste compost that is not sufficiently removed NaCl was considered to be improper due to salt accumulation in soils and plant growth inhibition by salt stress. The purpose of this study is to decompose NaCl in food waste compost using triple salt and this method is differ from existing chemical method. Also, reaction of NaCl with triple salt produced KCl that is basic material of potassium fertilizer. Moreover Also, there was temperature rise of average $5^{\circ}C$ as result that apply triple salt in food waste 600 ton in food wast composting productive capacity. Obvious odious smell reduction effect appeared pretreatment process and fermentation process with temperature rise and this is because triple salt activation of aerobe and removes odious smell cause material by salt content decrease effectively.

• Journal of the Korea Organic Resources Recycling Association
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• v.3 no.2
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• pp.59-68
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• 1995

Composting facilities are operated with air and moisture control. Composting effects on two operating factors was analysed changing aeration rate with and without water addition to maintain the optimun moisture level. Though the composting facilties are provided with appropriate surroundings for compositing, operating temperature is set for decomposition rate. Accordingly control of decomposition phases was analysed by modeling the process of high and low decomposition phases with various operating temperature. A composting model of "The Library of Compost Engineering Software" developed by Roger T. Haug Inc. in U.S.A. was applied in modeling. As result of this study, operation with optimum moisture has more sensitive temperature to aeration fluctuation and lead to higher reaction rate with lower aeration than operation with poor moisture. Decomposition rate in composting facilities depend on slow decomposition phase because high rate decomposing substances already have been decomposed before entire process is not completed. In order to enhance decomposition rate of organics, effective decomposition in slow decomposition phase needs to be focused.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.11
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• pp.1054-1062
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• 2010

Oxidative coupling reactions of humic substances (HS) can be catalyzed by a variety of natural extracellular enzymes and metal oxides. In this study, property changes of HS induced by a natural enzyme, horseradish peroxidase (HRP), and the effect of it to microfiltration (MF) were investigated. PAHA was transformed by oxidative coupling reaction with HRP and hydrogen peroxide ($H_2O_2$), verifying the catalytic effects of the HRP. Size exclusion chromatography (SEC) revealed that weight-average molecular weight (MWw) of PAHA was proportionally increased with the dosages of HRP and $H_2O_2$, indicating the transform action of HS into larger and complex molecules. An increase in the conformational stability of HS was achieved through the promotion of intermolecular covalent bondings between heterogeneous humic molecules. Spectroscopic analysis (fluorescence and infrared spectroscopy) proved that functional groups were transformed by the reaction. Additionally, HS and transformed products were undergone microfiltration (MF) to examine the treatment potential of them in a water treatment facility. Original HS could not be removed by MF but larger molecules of transformed products could be removed. Meanwhile, transformed products caused more fouling on the filtration than original HS. This results proved that natural organic matter (NOM) can be removed by MF after its increase in molecular size by oxidative coupling reaction.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.2
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• pp.95-103
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• 2009

In order to improve the electrochemical, mechanical and electrocatalytic characteristics, engineering plastic of polyether ether ketone (PEEK) as polymer matrix was sulfonated (SPEEK) and the organic-inorganic blend composite membranes has been prepared by loading heteropoly acids (HPAs), including tungstophosphoric acid (TPA), molybdophosphoric acid (MoPA), and tungstosilicic acid (TSiA). And then these were covalently cross-linked (CL-SPEEK/HPA) as the electrolyte and MEA of polymer electrolyte membrane electrolysis (PEME). As a result, the optimum reaction conditions of CL-SPEEK/HPA was established and the electrochemical characteristics such as ion conductivity ($\sigma$) were in the order of magnitude: CL-SPEEK /TPA30 (${\sigma}=0.128\;S/cm^{-1}$) < /MoPA40 (${\sigma}=0.14\;S/cm^{-1})$ < /TSiA30 (${\sigma}=0.22\;S/cm^{-1}$) at $80^{\circ}C$, and mechanical characteristics such as tensile strength: CL-SPEEK /TSiA30 $\fallingdotseq$ /MoPA40 < /TPA30. Consequently, in regards of above characterisitics and oxidation durability, the CL-SPEEK/TPA30 exhibited a better performance in PEME than the others, but CL-SPEEK/MoPA40 showed the best electrocatalytic activity of cell voltage 1.71 V among the composite membranes. The dual effect of higher proton conductivity and electrocatalytic activity with the addition of HPAs, causes a synergy effect.

• Applied Chemistry for Engineering
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• v.34 no.1
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• pp.51-56
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• 2023

Composite membranes consisting of TiO₂ nanoparticles (NPs) and porous polymers have been widely utilized in photocatalytic water treatment because the composite membranes can allow an easy recovery of NPs after the photocatalytic reaction as well as the reduction of fouling in the membrane. However, the photocatalytic efficiency of the immobilized TiO₂ NPs in the composite membranes has been discussed to a limited degree. In this study, we prepared polyethersulfone (PES)/TiO₂ composite membranes to study the photocatalytic decomposition of organic dyes under light illumination. The decomposition kinetics of dye molecules by the PES/TiO₂ composite membranes and colloidal TiO₂ NPs have been compared to discuss the photocatalytic efficiency of NPs before and after their immobilization on the polymer membrane.

• Journal of Environmental Science International
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• v.18 no.3
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• pp.299-308
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• 2009

We manufactured PVA-derived hydrogels using a foam generation technique that has been widely used to prepare colloidal gas aphrons(CGA). These gels were differentiated to the conventional gels such as for medical or pharmaceutical applications, which have tiny pores and some crystalline structure. Rather these should be used in de-pollution devices or adhesion of cells or biomolecules. The crosslinkers used in this work were amino acid, organic acid, sugars and lipids(vitamins). The structures of the gels were observed in a scanned electron microscope. Amino acids gels showed remarkably higher swelling ratios probably because their typical functional groups help constructing a highly crosslinked network along with hydrogen bonds. Boric acid and starch would catalyze dehydration while structuring to result in much lower water content and accordingly high gel content, leading to less elastic, hard gels. Bulky materials such as ascorbic acid or starch produced, in general, large pores in the matrices and also nicotinamide, having large hydrophobic patches was likely to enlarge pore size of its gels as well since the hydrophobicity would expel water molecules, thus leading to reduced swelling. Hydrophilicity(or hydrophobicity), functional groups which are involved in the reaction or physical linkage, and bulkiness of crosslinkers were found to be more critical to gel's cross linking structure and its density than molecular weights that seemed to be closely related to pore sizes. Microscopic observation revealed that pores were more or less homogeneous and their average sizes were $20{\mu}m$ for methionine, $10-15{\mu}m$ for citric acid, $50-70{\mu}m$ for L-ascorbic acid, $30-40{\mu}m$ for nicotinamide, and $70-80{\mu}m$ for starch. Also a sensory test showed that amino acid and glucose gels were more elastic meanwhile acid and nicotinamide gels turned out to be brittle or non-elastic at their high concentrations. The elasticity of a gel was reasonably correlated with its water content or swelling ratio. In addition, the PVA gel including 20% ascorbic acid showed fair ability of cell adherence as 0.257mg/g-hydrogel and completely degraded phenanthrene(10 mM) in 240 h.

• Journal of the Korean Chemical Society
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• v.27 no.3
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• pp.213-217
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• 1983

Devices that mimic the natural photosynthetic pathway are of considerable interest as fuel sources. Quantum yield of viologen radical formation in several water-in-oil microemulsion system were measured. The yield of hexadecylviologen radical formation in microemulsion system using EDTA as an electron donor, ruthenium bipyridinium complex as photosensitizer, and hexadecylviologen as an electron acceptor was 12%. When benzylnicotinamide was inserted in the interface of the microemulsion and azo compound was dissolved in oil face, the quantum yield of hydroazo compound was 0.16. Organic dye (Rose bengal) was used as photosensitizer for the photoinduced electron transfer reaction. In anionic microemulsion no electrontransfer was observed.

• Journal of Microbiology and Biotechnology
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• v.29 no.7
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• pp.1071-1077
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• 2019

Natural gamma-decalactone (GDL) produced by biotransformation is an essential food additive with a peach-like aroma. However, the difficulty of effectively controlling the concentration of the substrate ricinoleic acid (RA) in water limits the biotransformation productivity, which is a bottleneck for industrialization. In this study, expanded vermiculite (E-V) was utilized as a carrier of RA to increase its distribution in the medium. E-V and three commonly used organic compounds were compared with respect to their effects on the biotransformation process, and the mechanism was revealed. Scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis indicated that RA was physically adsorbed onto the surface of and inside E-V instead of undergoing a chemical reaction, which increased the opportunity for interactions between microorganisms and the substrate. The highest concentration of GDL obtained in the medium with E-V was 6.2 g/l, which was 50% higher than that in the reference sample. In addition, the presence of E-V had no negative effect on the viability of the microorganisms. This study provides a new method for producing natural GDL through biotransformation on an industrial scale.

• Journal of Environmental Science International
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• v.10 no.2
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• pp.119-127
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• 2001

The Keum river is one of the important river in Korea and has a drainage area of 9,873$\textrm{km}^2$. The Keum river is deepening pollution state due to development of the lower city and construction of a industrial complex. The water quality of the Keum river come to eutrophication state and belong to III grade of water quality standard. The concentration BOD in river is affected by the organic loading from a tributary and the algae biomass that largely happen to under eutrophication state. In the eutrophic water mass such as the Keum river, the autochthonous BOD was very important part for making a decision of water quality management, because it was accounted for majority of the total BOD. The purpose of this study was to survey the chatacteristics of water quality in summer and to estimate reaction coefficient. Also, we studied to correlationship between chlorophyll a and BOD(COD) for estimation of the autochthonous BOD. The correlationship between chlorophyll a and BOD(COD) were obtained through the culture experiment of phytoplankton in the laboratory. The results of this study may be summarized as follows ; The characteristics of water quality in summer were belong to III~IV grade of water quality standard as BOD and nutritive condition is very high. The BOD, ammonia nitrogen and phosphate loadings in Miho stream which inflowing untreated sewage from Chungju city was occupied with 64.07%, 26.36%, 46.08%, respectively. Maximum nutrient uptake (Vmax) was 0.4400$\mu$M/hr as substrate of ammonia nitrogen, 0.1652$\mu$M/hr as substrate of phosphate. Maximum specific growth rate ($\mu$max) was 1.2525$hr^{-1}$ as substrate of ammonia nitrogen, 1.5177$hr^{-1}$ as substrate of phosphate. The correlation coefficient between chlorophyll a and BOD by the culture experiment were found to be 0.911~0.935 and 0.942~0.947 in the case adding nutrient and no adding nutrient, respectively. The correlation coefficient between chlorophyll a and COD through the culture experiment were found to be 0.918~0.977 and 0.880~0.931 in the case adding nutrient and no adding nutrient, respectively. The autochthonous BOD(COD) was estimated to the relationship between BOD(COD) and chlorophyll a. The regression equation were found to be autochthonous BOD=(0.045~0.073)${\times}chlorophyll$ a and autochthonous $COD=(0.137~0.182){\times}chlorophyll$ a.

• Journal of the Korean Ceramic Society
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• v.56 no.6
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• pp.534-540
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• 2019

Carbon dioxide emissions involved in global warming are one of the most important issues in the world, and carbon dioxide emissions from the cement industry are about 7% of total carbon dioxide emissions. Thus, reduction in the amount of utilized cement can contribute to a reduction of carbon dioxide emissions. The average life of concrete is 20 ~ 30 years, and if concrete life can be improved by ten years, cement use will be much lower. In this study, we examined the use and effect of fructan from microbes as a method for the densification of the pore structure of cement. The effect of fructan on the hydration reaction and pore distribution, as well as the water absorption of hardened cement mortar were studied. Pores distribution increased in mesopore OPC, and absorption rate was found to decrease with the use of fructan, which has a glue-like and swelling character.