• Applied Biological Chemistry
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• v.49 no.3
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• pp.170-174
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• 2006

For the purpose of developing a high quality agricultural microbial inoculant, methods and materials for improving encapsulation were investigated. Preparation of capsule was conducted by improving extrusion system with micro-nozzle and peristaltic pump. The sodium alginate was selected because of its cheapness, stability of cells, and gel formation ability. The yields, physical properties and gel formation abilities of extractable alginate from sea tangle were investigated by hot water extractable and alkali soluble methods. The extraction yields of hot water extractable alginate (HWEA) and alkali soluble alginate (ASA) from sea tangle were 8 and 20%, respectively. The HWEA was almost not viscous even in 1.5% of the sample solution, whereas the ASA was very highly viscous in above 3% sample solution. The gel formation ability of each samples varied from 1.5% to 5% and the ASA showed a good gel formation ability at 3% solution as commercial alginate (CA). The soil microbial inoculant, Bacillus thuringiensis, Bacillus subtilis, Lactobacillus plantarum and Geotrichum candidum encapsulated sodium alginate with starch and zeolite for stabilizer. The survivability of encapsulated soil microbial inoculant using alginate without stabilizer appeared to be 66, 52, 70 and 50%, respectively. Inclusion of starch and zeolite with alginate bead increased viabilities in Bacillus sp. and Geotrichum candidum by 81-83% and 89%, respectively.

• Clean Technology
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• v.16 no.1
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• pp.39-45
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• 2010

In this paper, 4 bundle modules of PVDF hollow fiber membrane from Woori Tech company (Korea) were manufactured in a treatment capacity of 10 ton/day. A membrane bioreactor (MBR) pilot plant was installed at Sooyoung Wastewater Treatment Plant in Busan. An alternating aeration process was selected to avoid the concentration profile of suspended solid (SS) in the MBR. For stable operation, raw wastewater with mixed liquor suspended solid (MLSS) of about 1,000 ppm, which was in-flowed from the aeration tank of the wastewater treatment plant, was fed and filtered through the pilot plant. Subsequently the pilot plant were washed three times with washing water: once with ethanol solution, once with a solution of 5% NaOCl, and finally with washing water. After the chemical washing, the remaining water in the MBR was fed into the pilot plant. As a result, the SS removal efficiency was found to be more than 99.9%. The amount of filtrate with the aeration tank influent decreased by 16%, compared with that from the initial conditions, giving rise to 30% increase in the suction pressure. These results were used to set up continuous operation conditions. The results from the continuous operation with influent MLSS of 1,900 mg/L showed that the SS removal efficiency was about 99.99% and that the amount of filtrate and the suction pressure were $42{\sim}52L/m^2$ and 16~20 cmHg, respectively, indicating stable operation of the pilot plant. However, for the reuse of wastewater, methods need to be sought to avoid growth of algae which affects the SS removal efficiency at inlet and outlet of the permeate tank.

• Journal of agriculture & life science
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• v.46 no.6
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• pp.51-57
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• 2012

This study was carried out to analyze chemical compositions of the fog water of a forest area, Jinju and to provide basic information for establishing measures on the acid fog water of forest area. The results are as follows: The pH of fog water was 4.3 in 2010, whereas the pH in 2011 was 4.0. The electrical conductivity of the fog water was $477.2{\mu}s$ in 2010, and $562.7{\mu}s$ in 2011. Among the anions, the concentration of $NO^{3-}$ was the highest, which recorded 267.1 mg/L in spring season and 279.1 mg/L in summer season, followed by $SO{_4}^{2-}$ at the concentration of 177.2 mg/L in spring season and 198.6mg/L in summer season. In autumn and winter, the concentration of $NO^{3-}$ was highest as 217.7 mg/L and 237.9 mg/L, respectively and followed by $SO{_4}^{2-}$, which concentration was 164.2 mg/L in autumn season and 190.1 mg/L in winter season (p<0.05). Among the cations, the concentration of $Ca^{2+}$ was 221.3 mg/L in spring and 233.7mg/L in summer, followed by $Na^+$ at 125.1 mg/L in spring season and 131.7 mg/L in summer In autumn and winter, the concentration of $Ca^{2+}$ was highest at 196.8 mg/L and 198.8 mg/L, followed by $Na^+$ at the concentration of 97.1 mg/L in autumn and 117.2 mg/L in winter (p<0.05). The pH of the fog rain that causes acid mist showed the correlation with $Ca^{++}$ (1% of level), $EC(r=-0.9861^{**})$, $NO^{3-}$ ($r=-0.9677^{**}$), and $SO{_4}^{2-}$ ($r=-0.9510^{**}$). The regression equation on the factors affecting the generation of acidic fog rain was estimated to be a $Y(pH)=6.4627+0.9723X_2(EC)+0.9364X_4(NO_3{^-})+0.9044X_5(SO{_4}^{2-})+0.8049X_{10}(Ca^{2+})+0.6709X_8(K^+)\;(r^2=0.8787)$.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.5 no.1
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• pp.47-55
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• 1999

Applications of chitosan are related to molecular weight and degree of deacetylation(DOD) of chitosan completely. The molecular weight and DOD were greatly affected by the concentration of solution time and temperature. The degree of demineralization was not significantly different at $50^{\circ}C\;and\;70^{\circ}C$ after 30 minutes. Deproteinization decreased as process time increased. The nitrogen content was reached to 6.92% after 90 minute at $80^{\circ}C$, which is similar to theoretical nitrogen content of chitin. The DOD was 82.84% after 2 hours reaction and increased as the reaction time increased in the process. Viscosity and molecular weight are increased as recycling number of concentrated NaOH solution increased. Chemical, biological and physical properties of chitosan depend on the DOD and molecular size of the molecule. Tensile strength of the films from acetic acid solutions was between $28.9{\sim}33.6$ MPa and was generally higher than that of the films from lactic acid. Elongation of the films from lactic acid was between $97.0{\sim}109.7%$ and was generally higher than that of the films from the acetic acid. Water vapor permeability of the films prepared from lcetic acid solutions was between $1.9{\sim}2.3ng{\cdot}m/m^2{\cdot}s{\cdot}Pa$ and was generally higher than that of the films from the acetic acid.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.1
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• pp.8-15
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• 2021

TiO2 has been used in various fields such as solar cells, dental implants, and photocatalysis, because it has high physical and chemical stability and is harmless to the body. TiO2 nanofibers which have a large specific surface area also show a good reactivity in bio-friendly products and excellent photocatalysis in air and water purification. To fabricate TiO2 nanofibers, an electrospinning method was used. To observe the diameter of TiO2 nanofibers with fabrication variables, the fabrication variables was divided into precursor composition variables and process variables and microstructure was analyzed. The concentrations of PVP (Polyvinylpyrrolidone) and TTIP (Titanium(IV) isopropoxide) were selected as precursor composition variables, and inflow velocity and voltage were also selected as process variables. Microstructure and crystal structure of TiO2 nanofibers were analyzed using FE-SEM (Field emission scanning electron microscope) and XRD (X-ray diffraction), respectively. As-spun TiO2 nanofibers with an average diameter of about 0.27 ㎛ to 1.31 ㎛ were transformed to anatase TiO2 nanofibers with an average diameter of about 0.22 ㎛ to 0.78 ㎛ after heat treatment of 3 hours at 450℃. Anatase TiO2 nanofibers with an average diameter of 0.22 ㎛ can be expected to improve the photocatalytic properties by increasing the specific surface area. To change the average diameter of TiO2 nanofibers, the control of precursor composition variables such as concentrations of PVP and TTIP is more efficient than the control of electrospinning process variables such as inflow velocity and voltage.

• Horticultural Science & Technology
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• v.30 no.1
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• pp.42-49
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• 2012

This experiment was conducted to find out the effects of nitrous oxide ($N_2O$) on the postharvest quality of 'Janghowon hwangdo' peach fruits. Fruits were harvested at commercial maturity for marketing in late September, and treated with 70% $N_2O$ + 20% $O_2$ + 10% air, 80% $N_2O$ + 20% $O_2$, and 90% $N_2O$ + 10% $O_2$ for 48 h, and then stored at $15^{\circ}C$. No significant treatments for soluble sugar and titratable acidity contents were detected. However, good appearance and taste in peach fruit were maintained better in 80% $N_2O$ treatment than in air treatment. The treatment with 90% $N_2O$ had negative effects on weight loss and taste because of rotting by anaerobic fermentation. 80% $N_2O$ treated fruit had significantly higher fungus (Botrytis cinerea) growth inhibition of saprogenic approximately than air treatment until 12 days of storage. The browning and rotting at surface of peach were also retarded when peaches were treated with 80% $N_2O$ before they were artificially wounded. The activity of polyphenol oxidase (PPO) was inhibited about 80% in peach of 80% $N_2O$ treatment compared with in air treatment. The result showed that 80% $N_2O$ treatment was able to extend the shelf life of peach fruits through maintaining taste and inhibition of softening and browning by rotting and wounding during storage.

• Journal of Animal Science and Technology
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• v.54 no.2
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• pp.133-139
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• 2012

A bacterium, identified as $Bacillus$ $amyloliquefacies$, CNL-90 using 16S rDNA analysis, was isolated from malt grain. The optimal activities of its ${\alpha}$-amylase and protease were observed at pH 6 and $60^{\circ}C$, and at pH 6 and $50^{\circ}C$, respectively although their activities remained stable at pH 7 and $40^{\circ}C$for ${\alpha}$-amylase and at pH 7 and $50^{\circ}C$ for protease. After solid-state fermentation of $B.$ $amyloliquefacies$, CNL-90 on wheat bran for 72hr or 144hr, the ${\alpha}$-amylase and protease activities were 170,000 and 290,000 units/kg, and 290,000 and 310,000 units/kg, respectively. The viable bacterial cell counts were $1.5{\times}10^9$ CFU/g and $2.2{\times}10^9$ CFU/g at 72hr and 144hr of the solid-state fermentation, respectively. A feeding trial with a total of 127 piglets was also conducted. The animals were divided into two groups: an experimental group fed with the fermented product (63 piglets) and a control group (64 piglets). The growth rate of the experimental group was 6.66% higher than that of the control group (P<0.05). The results of this study indicate that the ${\alpha}$-amylase and protease from $B.$ $amyloliquefacies$, CNL-90 can be used for industrial applications due to their activity in production of carbohydrate hydrolysates.

• Journal of the Korea Organic Resources Recycling Association
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• v.13 no.1
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• pp.61-70
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• 2005

In order to reduce salt(as NaCl) contents in food waste and to improve the quality of discharged wastewater produced during the recycling process of food waste for the purpose of compost and feed stuff, a salt reduction process by added water into food waste was developed. The pilot plant with a rotary type salt reduction equipment to manage continuously 0.5 ton food waste per hour was constructed and the efficiency was tested. The amount of added water was calculated by the water content and the efficiency of dewatering process of food waste. Approximately 0.8 liter water per a kilogram of food waste was injected into the reactor in which food waste was pouring simultaneously, then diluted/mixed in a rotary reactor. About 1.1 liter of leachate including added water was generated, but the leachate contained a very high content of organic particles, so most particles were recovered by two step solid-liquid separation process. The first step was a gravitational filtering process using screens with a pore diameter of 1mm, and the second separation process was centrifugal process. Organic quality of food waste which had been desalted was maintained by inputting the entirely recovered organic particles. The efficiency of salt reduction of food waste was estimated by measuring a chloride anion by titration and salinity by a probe. The results by the two different measuring methods were always over 50%, and the quality of final wastewater was improved up to $200mg/{\ell}$ as TS(total solid) by an additional settling process after the two step solid-liquid separation process.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.1
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• pp.26-34
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• 2010

The electrocatalystic prperties of Pt-Co and Pt-Ni with heteropolyacids (HPAs) entrapped in covalently cross-linked sulfonated poly(ether ether ketone) (CL-SPEEK)/HPA membranes were investigated for water electrolysis. The HP As, including molybdophosphoric acid (MoPA), and tungstophosphoric acid (TPA) were both used as membrane additives and electrocatalysts. The membrane electrode assembly (MEA) was prepared by a nonequilibrium impregnation-reduction (I-R) method. $Pt(NH_3)_4Cl_2$, $NiCl_2$ and $CoCl_2$ as electrocatalytic materials and $NaBH_4$ as reducing agent were used. I order to enhance electrocatalytic activity, the catalyst layer prepared above was electrodeposited (Dep) with HP A. Surface morphologies and physico-chemical properties of MEA were investigated by means of SEM, EDX and XRD. The electrocatalytic properties of composite membranes such as the cell voltage and coulombic charge in CV were in the order of magnitude: CL-SPEEK/MoPA40 (wt%) > CL-SPEEK/TPA30 > Nafion117. In the optimum cell applications for water electrolysis, the cell voltage of Pt/CL-SPEEK-MoPA40/Pt-Co (Dep-MoPA) and Pt/CL-SPEEK-TPA30/Pt-Co (Dep-TPA) was 1.75 Vat $80^{\circ}C$ and $1\;A/cm^2$ and voltage efficiency was 87.1%. Also, the observed activity of Pt-Co (84:16 atomic ratio by EDX) is a little higher than that of Pt-Ni (86: 14). The current density peak of electrodeposited electrodes were better a little than those of unactivated electrodes based on the same membranes.

• Applied Chemistry for Engineering
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• v.5 no.2
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• pp.327-336
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• 1994

The synergistic effects in mechanical mixture catalysts of Mo-V-O and metal oxide were investigated for the selective oxidation of acrolein. The metal oxides used are $SnO_2$, ${\alpha}-Sb_2O_4$, $WO_3$, ${\alpha}-Al_2O_3$, CuO, $MnO_2$, $Cu_2O$, MgO, CoO, and ZnO. Mechanical mixtures of Mo-V-O plus $SnO_2$ or ${\alpha}-Sb_2O_4$ had resulted in higher conversion of acrolein and higher yield of acrylic acid than Mo-V-O. The origin of the synergy is attributed to the cooperation of Mo-V-O and $SnO_2$ or ${\alpha}-Sb_2O_4$, in which $SnO_2$ or ${\alpha}-Sb_2O_4$ forms dissociated oxygens at their oxygen vacancies and transports them to Mo-V-O. $Cu_2O$, MgO, CuO, and $MnO_2$, increased conversion of acrolein but decreased yield of acrylic acid. CoO and ZnO inhibited the catalytic performance of Mo-V-O. The different role of these metal oxides is explained in terms of their oxidation-reduction properties.