• Journal of the Korean Ceramic Society
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• v.29 no.10
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• pp.779-784
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• 1992

In producing cordierite glass-ceramics by sintering, following experiments were conducted in order to determine the optimum heat-treatment schedule for high-crystallinity and dense sintered body. The glass composition of 11.67MgO-29.46Al2O3-52.88SiO2-5P2O5-1B2O3 (wt%) was selected on the basis of the early experiment. The 3-step heat treatment schedule was determined by the results of DTA, Dilatometric measurement and high-temperature XRD, where the particle-size-controlled glass powder was used. The degree of densification and the crystallinity were evaluated by the measurement of the bulk density and X-ray scattering intensity. The specimen fired with the optimum conditions showed ${\alpha}$-cordierite phase, relative density ∼98%, crystallinity ∼92%, thermal expansion coefficient ∼30${\times}$10-7/$^{\circ}C$, dielectric constant ∼5.5 and resistivity ∼1.0${\times}$1012 {{{{ OMEGA }}cm, respectively.

• Journal of the Korean Chemical Society
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• v.38 no.10
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• pp.769-773
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• 1994

Higher order structure of 5S rRNA isolated from Xanthomonas celebensis was examined using angiogenic extracted from milk. Angiogenin cleaved exclusively 3' P-O bonds on the far sides of pyrimidines in the single-stranded sequences of 5S rRNA. Whereas angiogenin acted only on the loop d of 5S rRNA at pH 7.0 in the presence of 10 mM $Mg^{2+}$, it acted on all the loops (a, b, c and d) except loop e in the absence of $Mg^{2+}$. In the absence of $Mg^{2+}$, bonds $U_{74}$-$G_{75}$, $U_{77}$-$A_{78}$ and $U_{103}$-$A_{104}$ were highly susceptible to the action of angiogenin both at pH 7.0 and at pH 3.5. On the other hand, at pH 3.5 in the absence of $Mg^{2+}$ angiogenin strongly cleaved the bond $C_{17}$-$G_{18}$ of loop a and the bond $U_{55}$-$G_{56}$ of loop b. The results lead us to the following conclusion. First, angiogenin can be used as one of the probes for the tertiary structure analysis of 5S rRNA. Second, the structure of loop d of 5S rRNA is variable depending on the concentrations of $Mg^{2+}$ and $H^{1+}$.

• Journal of Mushroom
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• v.10 no.3
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• pp.129-135
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• 2012

This study was carried out to investigated optimum mixing ratio of Korean natural Cudrania tricuspidata for production of functional oyster mushroom. Total nitrogen and carbon source of Cudrania tricuspidata was 0.27% and 40.9%, respectively and C/N ratio was 152. Total nitrogen source and pH of substrates mixed with Cudrania tricuspidata were 2.7~2.8 and 4.9~5.1, respectively. The contents of $P_2O_5$, CaO, MgO and $Na_2O$ were no significant difference. Mycerial growth was faster at Cudrania tricuspidata 10% than that of control, but the other treatment was slower. Yields of fruiting body was the highest at Cudrania tricuspidata 20%, and diameter and thick of pileus were no significant difference to increase of Cudrania tricuspidata addition ratio. The L value of pileus was the highest at the Cudrania tricuspidata 20% during mushroom harvest, but there was no significant difference in the a-value and the b-value. Chemical contents of fruiting body were the highest at the Cudrania tricuspidata 30%.

• Journal of the Korean Ceramic Society
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• v.27 no.8
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• pp.991-1003
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• 1990

A precipitation method, one of the most effective liquid phase reaction methods, was adopted in order to prepare high-tech Al2O3/ZrO2 composite ceramics. Al2(SO4)3.18H2O, ZrOCl2.8H2O and YCl3.6H2O were used as starting materials and NH4OH as a precipitation agent, various types of metal hydroxides were obtained by single precipitation(series A) and co-precipitation(series B) method at the pH condition between 7 and 11. Fine Al2O3-ZrO2 powders were prepared at optimum calcination condition and the effects of ZrO2 on microstructures and mechanical properties of Al2O3 were investigated. The composition of Al2O3/ZrO2 composites wax fixed as Al2O3-15 v/o ZrO2(＋3m/o Y2O3). ZrO2 limited the grain growth of Al2O3 and increased grain size homogeneity of Al2O3 more effectively than MgO.Flexural strength values in Al2O3 and Al2O3/ZrO2 composites were 340-430 MPa and 540-820 MPa, respectively, and the effect of strength improvement showed 20-50% by adding ZrO2 to Al2O3. Fracture toughness of Al2O3/ZrO2 composites was improved by stress-induced phase transformation of tetragonal ZrO2 and toughening effect by microcrack was not observed. Also, ZrO2 particles located at Al2O3 grain junction contributed to toughening, while spherical ZrO2 particles located within Al2O3 grain did not contribute to toughening. Weibull moduli of Al2O3 ceramics and Al2O3/ZrO2 composites of series A and series B were 4.34, 5.17 and 9.06, respectively. Above 0.5 of failure probability, strength values in Al2O3 ceramics and Al2O3/ZrO3 composites of series A and series B were above 400 MPa, 700 MPa and 650 MPa, respectively.

• Journal of agriculture & life science
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• v.46 no.1
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• pp.163-176
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• 2012

TTo increase productivity of a strong extracellular alkaline protease (BCAP), stable strains of Bacillus clausii I-52 carrying another copy of BCAP gene in the chromosome were developed. Integrative vector, pHPS9-fuBCAP carrying BCAP promoter, ribosome binding site, signal sequence and active protease gene was constructed and transferred into B. clausii I-52, and integration of the constructed plasmid into chromosome was identified by PCR. An investigation was carried out on BCAP production by B. clausii I-52 and transformant C5 showing the highest relative activity of alkaline protease using submerged fermentation. Maximum enzyme activity was produced when cells were grown under the submerged fermentation conditions at $37^{\circ}C$ for 48 h with an aeration rate of 1 vvm and agitation rate of 650 rpm in a optimized medium (soybean meal 2%, wheat flour 1%, sodium citrate 0.5%, $K_2HPO_4$ 0.4%, $Na_2HPO_4$ 0.1%, NaCl 0.4%, $MgSO_47H_2O$ 0.01%, $FeSO_47H_2O$ 0.05%, liquid maltose 2.5%, $Na_2CO_3$ 0.6%). A protease yield of approximately 134,670U/ml was achieved using an optimized media, which show an increase of approximately 1.6-fold compared to that of non-transformant (83,960 U/ml). When the stability of transformant C5 was examined, the integrated plasmid pHPS9-fuBCAP was detected in the transformant after cultivation for 8 days, suggesting that it maintained stably in the chromosomal DNA of transformant C5.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.1
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• pp.97-102
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• 2000

This study was carried out to investigate the effects of operating temperatures on decomposition and physicho-chemical properties of household food wastes in a fermentation dryer, which was manufactured by Samwoo Co. Ltd. The household food wastes of 100 kg can be put and dried in this dryer at once. The experiments were performed at each temperature of $35^{\circ}C$, $45^{\circ}C$, $55^{\circ}C$ and $70^{\circ}C$ for two days respectively. The samples taken at the fixed time were dried at $105^{\circ}C$ and analyzed to find the decomposition rate and the concentration of each substance. The results obtained were as follows: The decomposition rate at 35 and $70^{\circ}C$ was the highest and showed the similar tendency during the experimental period. The higher the operating temperature was, the faster the water content of the composting material reduced. pH value increased at the operating temperature of 55 and $70^{\circ}C$ and was higher than at the other operating temperatures. Nitrogen content did not show any tendency during the experimental period. $P_2O_5$ and CaO content increased during the experimental period but MgO, $K_2O$ and NaCl were not accumulated. Cu content based on dry matter was in the range of ND~100.4 mg/kg and Cd, Pb and Cr were not detected.

• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.419-424
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• 2005

Effect of temperature($22-32^{\circ}C$), pH(5-7) and medium composition on the mycelial growth for the submerged culture of Inonotus obliquus. The concentrations of glucose, starch, peptone, yeast extract, $K_2HPO_4$, $MgSO_4{\cdot}7H_2O$ and $CaCl_2$ were examined in the ranges of 30-120 g/L, 0-10 g/L, 0-20 g/L, 0-15 g/L, 0-2 g/L, 0-1.5 g/L and 0-0.5g/L, respectively. The maximum mycelial growth of Inonotus obliquus was obtained for $26-27^{\circ}C$ and pH 6. The concentrations of glucose, yeast extract and $CaCl_2$, which gave the maximum mycelial growth of Inonotus obliquus, were 70 g/L, 5 g/L and 0.1 g/L, respectively. In the cases of starch, peptone and $K_2HPO_4$, the mycelial growth of Inonotus obliquus increased with increasing the concentrations. However, as the concentration of $MgSO_4{\cdot}7H_2O$ increased, the mycelial growth of Inonotus obliquus decreased. The medium for maximum mycelial growth of Inonotus obliquus consisted of (per 1 L): glucose, 70 g; peptone, 5-20 g; starch, 10 g; yeast extract, 5 g; $K_2HPO_4$, 2 g and $CaCl_2$, 0.1 g.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.6
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• pp.945-949
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• 1994

Chondroitin sulfate (Chs) contents in edible snail , Achatina fulica Bowdich , andits processed meat extracts were determined by high-performance liquid chormatogrpahy(HPLC) and spectrophotometric method. Spectrophotometric method was based on the precipitation of acriflavine by ChS, and HPLC method was based on the detection of two unsaturated disaccharides, 2-acetamido-2-deoxy-3-O-($\beta$ -D-gluco-4-enepyranosyluronic acid)-4-O-sulfo-D-galactose($\Delta$Di-4S) and 2-acetamido-2deoxy-3-O-($\beta$-D-gluco-4-eepyranosyluronic acid)-6-O-sulfo-D-galactose ($\Delta$야-6S) librated from ChS byenzymeatic digestion with chondroitinase ABc. the ratio of 125$\mu$mol of sodium hydroxide to mg of ChS and 8$0^{\circ}C$ of reaction temperature were proper for alkaline hydrolysis to remove protein residue form ChS. In assay preparation for HPLC ethod, the iptimum concentration of the enzyme chondroitinase ABc was 0.15 unit per 50 $\mu\textrm{g}$ of ChS at a fixed reaction time (30 min) and pH 8.0 using Tris buffer. ChS content in edible snail was 177.6mg% by spectrophotometric method and 153.5mg% by HPLC method and those in the processed meat extract was 71.3mg% by spectrometric method ad 62.8mg% by HPLC method, respectively.

• Journal of The Korean Society of Grassland and Forage Science
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• v.13 no.1
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• pp.49-57
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• 1993

The main experiment related to this report was undertaken to assess the effects of two rates of $Ca(OH)_2$ (0, 250 kg/10a only at establishment) and five rates of N-$P_{2}O_{5}$-$K_2O$ (0-0-0, 0-10-10, 6-15-15, 12-20-20, 24-25-20 kg/10a/year) on the pasture establishment, on forage yield and quality, vegetation etc. After this 10-year main experiment, this pasture had been used to assess the effects of the above treatments on the soil characteristics in oversown hilly pasture of a grass-clover sward. This 1st part is concerned with the soil properties of pH-value. OM, T-N, avail. $P_{2}O_{5}$ and $P_{2}O_{5}$ absorption coefficient, and lime requirement by the soil depth. 1. The pH of the topsoil(0~l5 cm) was lowered from pH 5.12 of before the experiment to 4.90 of when $Ca(OH)_2$ was applied and to 4.68 of when $Ca(OH)_2$ was not applied. The pH decrease was more evident with the increase of NPK application rate and in the upper part of the top soil(0.0~7.5 cm). The additional application of lime was necessary in all the experiment blocks due to the strong acidity of the soil, and the amounts of lime requirement were increased with increased application rates of NPK and soil depth. 2. The contents of organic matter and T-N were increased in all the blocks by the establishment of the hilly pasture, and were higher in $Ca(OH)_2$ applied blocks than non-applied blocks. The contents were inversely correlated with the soil depth. No correlation was observed between the contents and the application rates of NPK. 3. The content of available $P_{2}O_{5}$-$K_2O$, was increased with the increased application of P, especially in the upper part of top soil. The content in the upper part(0.0~7.5 cm) was about twice of that in the lower part(7.5~15.0 cm). Since the contents of available $P_{2}O_{5}$$P_{2}O_{5}$/10a/year were applied, respectively), it is necessary to decrease the application rate of $P_{2}O_{5}$, gradually. The $P_{2}O_{5}$ absorption coefficient in topsoil (0.0~15.0 cm) was more or less higher when no lime and less $P_{2}O_{5}$, was applied. No correlation was observed in subsoil. 4. Further studies on the methods, rates, time of additional application of lime, and on the methods of decreased apllication of $P_{2}O_{5}$ should be performed for better management of oversown hilly pasture.

• Biomolecules & Therapeutics
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• v.8 no.1
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• pp.32-37
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• 2000

Recently new soybean saponins with D DMP (2,5-dihydroxy-6-methyl-2,3,- dihydro-4H-pyran-4-one) moiety have been isolated from legumes. The purpose of this study is to characterize ROS scavenging activities of DDMP saponins ($\alpha$g, $\beta$g saponin) isolated from Glycine max (L.) Merrill. The scavenging activity on OH was examined in terms of lipid peroxidation in the rat liver homogenates and the same activity on $O_2$ was also determined in the xanthine-xanthine oxidase system, respectively. Up to 0.25 mg DDMP saponins ($\alpha$g and $\beta$g saponins) did not cause any significant effects on the prevention of lipid peroxidation as compared with the control group. In terms of superoxide scavenging activities, 0.25 and 0.5 mg $\alpha$g saponin inhibits only 2.6% and 5.5% (p<0.05) of the control group, respectively. However, $\alpha$g saponin dose-dependently (p<0.01, r=0.955) inhibits the formation of superoxide radical unto 21.3% of the control group with a maximal dose of 0.5 mg (p<0.01), equivalent to 0.17 units of superoxide dismutase activity.