• Korean Journal of Materials Research
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• v.22 no.1
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• pp.54-60
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• 2012

The particle size of MgO was examined as a function of the Na content in $Mg(OH)_2$ powders and the calcination temperature. $Mg(OH)_2$ suspension was obtained by dropwise precipitation of $Mg(NO_3)_2{\cdot}6H_2O$ and NaOH solutions. The suspension was diluted by varying the dilution volume ratio of distilled water to $Mg(OH)_2$ suspension to change the Na salt concentration in the suspension. $Mg(OH)_2$ slurry was filtered and dried at $60^{\circ}C$ under vacuum, and then its $Mg(OH)_2$ powder was calcined to produce MgO with different amount of Na content at $500\sim900^{\circ}C$ under air. Investigation of the physical and chemical properties of the various MgO powders with dilution ratio and calcination temperature variation was done by X-ray diffraction, transmission electron microscopy, BET specific surface area and thermal gravimetric analysis. It was observed that MgO particle size could depend on the condition of calcination temperature and dilution ratio of the $Mg(OH)_2$ suspension. The particle size of the MgO depends on the Na content remaining in the $Mg(OH)_2$ powder, which powder was prepared by changing the dilution ratio of the $Mg(OH)_2$ suspension. This change increased as the calcination temperature increased and decreased as the dilution ratio increased. The growth of MgO particle size according to the increase of temperature was more effective when there was a relatively high content of Na. The increase of Na content lowered the temperature at which decomposition of $Mg(OH)_2$ to MgO took place, thereby promoting the crystal growth of MgO.

• Journal of Animal Environmental Science
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• v.15 no.3
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• pp.281-288
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• 2009

The objective of this study is to predict the expansion possibility of treatment capacity in public livestock manure treatment plant (PLMTP) integrated individual farmhouses. According to the treatment efficiency and cost reducing effect, expansion possibility was examined using three cases; (i) decrease of influent concentration from 20,000 mg/L BOD to 1,000 mg/L BOD, (ii) maintenance of low concentration influent with minimum revising existing facilities (BIOSUF) and (iii) maintenance of low concentration influent without revising existing facilities (liquid corrosion method, LCM). In BIOSUF, the treatment capacity increased from 130 ton/day to 300 ton/day. Also, LCM resulted in expansion of treatment capacity from 210 ton/day to 250 ton/day while that of designed concentration influent decreased from 210 ton/day to 190 ton/day. The treatment costs were 14,674 won/ton and 9,929 won/ton for BIOSUF and LCM, respectively. After some revisions, it will be changed to 7,221 won/ton and 8,277 won/ton. Therefore, it must be considered that the livestock manure treats to low concentration and flows into PLMTP for the efficient operation and reducing treatment cost.

• The Korean Journal of Food And Nutrition
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• v.14 no.2
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• pp.161-166
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• 2001

The optimum condition for production of yeast extract by autolysis and enzymatic method were studied with waste brewers\` yeast. The major components of brewer\`s yeast in proximate compositions were carbohydrate(46.0%) and protein(41.7%). There was a little appreciable difference in the promaximate composition of waste brewers\` and bakery yeast. The major minerals were identified as K, P, Mg and Ca, and their contents were about 1,659.7%, 1,197.4mg%, 210.4mg% and 105.6mg%, respectively. The major vitamins were identified as vitamin C and vitamin B group, and their contents were about 7.9IU/100g and 4.2IU/100g, respectively. The optimum yeast concentration in the reaction suspension was 10% (w/v) waste brewer\`s yeast slurry. The protein content in brewer\`s yeast extract was increased with addition of NaCl as plasmolyzers. However, the plasmolyzer effect of ethanol a little showed as the concentration increasd from 3% ∼7%. The 5\`-nucleotides(5\`-GMP and 5\`-IMP) content in brewer\`s yeast extract was increased with addition of glucanase. The total content of 5\`-nucleotides (5\`-GMP and 5\`-IMP) increased by 160% than those by the autolysis of waste brewer\`s and bakery yeast.

• Applied Biological Chemistry
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• v.34 no.2
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• pp.125-129
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• 1991

This experiment was carried out to examine the MBC adsorption on clay minerals by the slurry method. The adsorption of MBC on Kaolinite nearly reached equilibrium after shaking lot 2hrs. but on Bentonite and Zeolite, 10hrs., respectively. The adsorption amount was in the order of Zeolite>Bentonite>Kaolinite, and Na-saturated clay mineral adsorbed more MBC than Mg-saturated clay mineral did. The more the amount of clay minerals, the more MBC was adsorbed by clay minerals, whereas the amount of MBC adsorbed per unit gram of clay minerals reduced and Kd value cf MBC was greatest on the Na-Zeolite. The lower the pH of the water-clay system at each concentration, the more MBC was adsorbed by clay minerals. The pH dependence of the adsorption of MBC may be due to protonation of MBC in acid solution.

• Journal of the Mineralogical Society of Korea
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• v.20 no.1 s.51
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• pp.1-6
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• 2007

Hectorite was synthesized by a two-step hydrothermal process from $Mg(OH)_{2}$, water glass (${\sim}30\;wt%\;SiO_{2}$) and Li-compound at $90{\pm}5^{\circ}C$. The product shows excellent dispersion and swelling properties. The mixture of the starting materials was heated in a glass vessel for the first reaction with continuous stirring and the pH of the solution was adjusted to $6{\sim}8$, resulting in the formation of a precursor of hectorite. The excess salt components were washed out from the resulting slurry and then was matured in the glass vessel for the 2nd reaction. Li compound was added during the reaction. After a 10 h retention, the gel of hectorite was formed. The XRD pattern of the synthesized one was coincided with that of natural hectorite and SEM study revealed uniform grains 50 m in diameter. The d001 basal spacing of the product moved from 12 to $17.4\;{\AA}$ after glycolation treatment. The measured value of CEC and the swelling capacity was 90 cmol/kg and $60{\sim}70\;mL/2\;g$, respectively.

• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.252-258
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• 1999

Tetramethyl orthosilicate (TMOS) was obtained by the direct synthesis of methanol with metallic silicon including copper compound as a catalyst and zinc compound as a promoter. The effects of the preheating temperature and the preparation method of the contact mass on TMOS synthesis were investigated. The composition effects of the contact mass which was composed of metallic silicon with copper catalyst and various metallic halide promoters including Zn, Sn or Cd compound were studied also. The best performance on TMOS synthesis was observed on a mixed bed reactor containing metallic silicon preheated with CuCl as a catalyst and $ZnCl_2$ as a promoter. When Cu/Si = 7 wt %, Zn/Cu = 7 wt % was mixed in a slurry phase and activated into contact mass at $380^{\circ}C$, the average selectivity was 87.2% in the silicon consumption of 69.2% at $220^{\circ}C$.

• Applied Chemistry for Engineering
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• v.19 no.2
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• pp.185-190
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• 2008

In order to increase the surface area of electrodes for electrosorption, porous carbon electrodes were fabricated by a wet phase inversion method. A carbon slurry consisting of a mixture of activated carbon powder (ACP), polyvinylidene fluoride (PVdF), and N-methyl-2-pyrrolidone (NMP) as a solvent was cast directly on a graphite sheet. The cast film was then immersed in pure water for phase inversion. The physical and electrochemical properties of the electrodes were investigated using scanning electron microscopy (SEM), porosimetry, and cyclic voltammetry. The SEM images verified that the pores of various sizes were formed uniformly on the electrode surface. The average pore sizes determined for the electrodes fabricated with various NMP contents ranged from 64.2 to 82.4 nm and the size increased as the NMP content increased. All of the voltammograms showed a typical behavior of charging and discharging characteristic at the electric double layer. The electrical capacitance ranged from 3.88 to $5.87F/cm^2$ depending on the NMP contents, and the electrical capacitance increased as the solvent content decreased. The experimental results showed that the solvent content is an important variable controlling pore size and ultimately the capacitance of the electrode.

• Journal of Animal Environmental Science
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• v.15 no.1
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• pp.69-74
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• 2009

A survey questionnaire that addressed the issues to manure compost producers and users was prepared. The questionnaire addressed three main topics as follows: 1) types of manure treatment and composting facilities are being operated, 2) quantity of manure compost produced and used, 3) problems experienced in producing and using manure compost. A total of 30 manure compost producers and 10 manure compost users were interviewed. Solid manure are applied to composting. Slurry and wastewater are simplified aeration method to produce liquid fertilizer. The open elongated type manure composting are generally used on manure compost centers jointly used by several farms. The amount of annually manure compost production was most common in the range of $5{\sim}10$ thousand tons per manure compost center. The manure compost utilization and cucumber yield were mostly $6{\sim}15$ tons and $20{\sim}27$ tons per 10a of cucumber farmland, respectively. Environmentally friendly use both of manure compost and chemical fertilizer are recommended for natural recycling agriculture.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.475-481
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• 1999

Yeast extracts were prepared using either autolysis or enzymatic digestion methods for industrial application of the Saccharomyces cerevisiae B24 strain developed previously to have high RNA content. Extraction ratio of yeast extract from yeast cell reached 65% when autolysis of yeast slurry having 10% solid content was induced at $50^{\circ}C$ and pH 5.0 by agitating with 100 rpm. However, neither 5'-IMP nor 5'-GMP was detected from the autolyzate. In another attempt to prepare a yeast extract S. cerevisiae B24 culture was treated at $90^{\circ}C$ and then treated by various enzymes including ${\beta}-1,3-glucanase$, phosphodiesterase (nuclease P1), adenylic deaminase, and a protease. The yeast extract prepared by the enzymatic digestion method contained 3.2g of 5'-IMP and 5'-GMP/100g dry yeast extract.

• Journal of the Korean GEO-environmental Society
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• v.7 no.6
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• pp.13-22
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• 2006

The geotextile have been used in filtration and drainage for over 30 years in many applications of civil and environmental projects. Geotextile tube is compound technology of filtration and drainage property of geotextile. Geotextile have been used for various types of containers, such as small hand-filled sandbags, 3-dimensional fabric forms for concrete paste, large soil and aggregate filled geotextile gabion, prefabricated hydraulically filled containers, and other innovative systems involving containment of soils using geotextile. They are hydraulically filled with dredged materials. It have been applied in coastal protection and scour protection, dewatering method of slurry, and isolation of contaminated material. Recently, geotextile tube technology is no longer alternative construction technique but suitable desired solution. This paper presents the behavior of geotextile tube composite structure by 2-D limit equilibrium and plane strain analysis. 2-D limit equilibrium analysis was performed to evaluate the stability of geotextile tube composite structure for the lateral load and also the plane strain analysis was conducted to determine the design and construction factors. Based on the results of this paper, the three types of geotextile tube composite structure is stable. And the optimum tensile strength of geotextile is 151kN/m and maximum pumping pressure is 22.7kN/m.