• Applied Chemistry for Engineering
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• v.24 no.4
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• pp.382-390
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• 2013

Foaming process of waste soda lime glasses by just chemical composition control of vitreous feed materials was investigated to find a novel and efficient recycling process. For the chemical composition control of feed materials, 10 wt. parts of $SiO_2$, 0.5 wt. parts of $Na_2SO_4$, 3.0 wt. parts of $B_2O_3$, and 0.3 wt. parts of carbon black as the foaming agent were mixed with 100 wt. parts of soda-lime vitreous feed powder. Proper conditions for foaming process in tunnel kiln are the foaming temperature of $830{\sim}850^{\circ}C$, the foaming time of 30~35 min, and the vitreous feed powder particle size of -325 mesh. Properties of foamed glass blocks obtained under these foaming conditions showed the density of $0.17{\sim}0.21g/cm^3$, thermal conductivity of $0.06{\pm}0.005kcal/h{\cdot}m{\cdot}^{\circ}C$, moisture absorption of 1.1~1.5%, and compressive strength of $20{\sim}30kgf/mm^2$.

• Composites Research
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• v.18 no.4
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• pp.27-34
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• 2005

Salt water spray and immersion tests were experimentally conducted for over 6 months to investigate the durability of glass fabric/phenolic composites under salt water environment. Mechanical properties such as tensile properties, flexural properties, and shear properties were evaluated and thermal analysis properties such as storage shear modulus, loss shear moduls, and tan 6 were obtained through a DMA. A change in chemical structures was analyzed through a FTIR. According to the results, mechanical properties and thermal analysis properties were sensitive to salt water environment and these properties began to degrade in increasing in exposure times. However, tensile and flexural moduli started to decrease and then slightly increase as increasing in exposure times due to plasticization and crosslinking in matrix as well as physical swelling in composites. Beyond a certain exposure times, these properties began to decrease as further increasing in exposure times. Also the shape and location of peaks in FTIR curves were insensitive to exposure times, but the intensity of peaks would be. finally we found that the durability of glass fabric/phenolic composites were affected on salt water immersion environment rather than salt water spray environment.

• Applied Biological Chemistry
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• v.32 no.4
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• pp.374-377
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• 1989

To optimize the enzymatic saccharification of raw-starch, reaction conditions by shaking with glass beads were adapted together with ${\alpha}-amylase$ from Streptomyces sp. 4M-2 and amyloglucosidase from commercial source. When raw-starch was degraded by the ${\alpha}-amylase$ in shaking flask with beads (raw-starch : bead in diam. of 3mm=1 : 5 by weight) at the shaker speed of 300rpm, the saccharification rate of corn and potato starch were increased up to 88% and 69% after 30 hrs of reaction, respectively. Application of the amyloglucosidase in combination with the ${\alpha}-amylase$ enhanced the rate of saccharifcation: 88% of saccharification was obtained in 6 hrs for raw-corn starch under the same reaction conditions as above.

• Journal of the Korean Society of Food Culture
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• v.21 no.2
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• pp.161-165
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• 2006

This study was examined the contents of solid, calcium, phosphorous, magnesium, protein, amino acid and collagen in beef leg and rib bone soup by various boiling time(1, 2, 4, 8, 12 hours). The results were as follows; as the boiling time increased, contents of solid, calcium, phosphorous, magnesium, protein, amino acid and collagen were increased. However, the boiling time increased, cloudiness (T%) was decreased. When we compared beef bone leg with the rib bone soup, rib bone soup was much nutritional contents than leg bone soup. In sensory evaluation of the soup boiled for 12 hours, added with 0.8% salt, rib bone stew was highly evaluated than leg bone soup.

• Korean Journal of Materials Research
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• v.9 no.7
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• pp.663-669
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• 1999

Ag thick film conductors were fabricated with Ag powders having different degree of dispersion and glasses having different viscosity, and then the relationship between microstructure and electrical properties of the Ag films was investigated. Under the same processing condition. the Ag thick film that was prepared with the well-dispersed Ag powder and glass having low viscosity had denser microstructure and lower resistance than those of the film which was fabricated with the agglomerated Ag powder and glass having high viscosity It is believed to be due to the fast micro rearrangement kinetics when the well dispersed Ag powder was used, and all the microstructure development kinetics were impeded when low viscosity glass used. It was found that theme fast microstructure development kinetics resulted in the dense microstructure and the lower sheet resistance of the films. Also, the saturation time, at which at a given temperature no further decrease in the sheet resistance was obtained, was found to be shortened when well-dispersed Ag powder and low viscosity glass were used.

• KSBB Journal
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• v.13 no.1
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• pp.114-118
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• 1998

The effects of fibron solubilization conditions on molecular weight distribution of enzymatically-hydrolyzed silk peptides were investigated. The weight-averaged molecular weights of silk proteins prepared by solubilization with calcium chloride, ethylenediamine and sulfuric acid were 41600, 3308, and 1268 dalton, respectively. Silk peptides in the average molecular weight range of 600-1200 dalton were obtained by protease treatment from solubilized silk fibroin. After the acid hydrolysis of silk protein using hydrochloric acid for 24 hr, silk protein was hydrolyzed to peptides whose average molecular weight and free amino acid content were 145 dalton and 80%, respectively. It was possible to control molecular weight distribution of silk peptides by the combination of solubilization and hydrolysis methods. Among the various treatment methods, acid solubilization followed by protease treatment had an advantage of molecular weight control for the peptide production.

• Tuberculosis and Respiratory Diseases
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• v.39 no.4
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• pp.304-309
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• 1992

Background: The alveolar macrophage may metabolize arachidonic acid through cyclooxygenase- and lipoxygenase- catalyzed pathways to produce a variety of metabolites of arachidonic acid. The production of these metabolites of arachidonic acid may enhance the defensive ability of the challenged lung. However, continued stimulation with the consequent production of proinflammtory metabolites of arachidonic acid, may ultimately enhance the disease process by contributing to chronic bronchoconstriction, fibrosis, and the persistent release of toxic oxygen species. Silicosis is an example of a disease process resulting from chronic exposure of the lung to foreign particles. This study was carried out to evaluate the changes of arachidonic acid metabolites from macrophages in experimental silicosis. Methods: We measured $PGE_2$, and $LTB_4$ in cultured macrophages taken from rats by radioimmunoassay at 24 and 48 hours after stimulation by silica dust, natural carbon dust, lipopolysaccharide, calcium ionophore (A23187) and medium (RPMI) as a control. For the experimental silicosis, 50 mg silica in 0.5 ml saline was administered intratracheally into the rat and grown to 20 weeks and measured $PGE_2$, and $LTB_4$ in the cultured macrophages lavaged from that rat. The used stimulants were the same as above. Results: 1) The amount of $PGE_2$ in the cultred macrophages from normal rat was significantly decreased in the group which was stimulated with silica dust for 48 hours compare with control non-stimulated group. 2) In the experimental silicosis group, $PGE_2$, release in cultured macrophages after 48 hours incubation with silica and natural carbon dust tended to be lower than those of non-stimulated group. 3) There were marked changes of $LTB_4$ in the groups of normal rats which were incubated with silica for 24, 48 hours and natural carbon for 48 hours compared with non-stimulated group. 4) In the experimental silicosis group, the release of $LTB_4$ was significantly increased macrophages cultured with silica and natural carbon dust after 24 and 48 hours incubation compared with non-stimulated group. Conclusion: The results of these studies suggest that the in vitro exposure of rat alveolar macrophge to silica and coal dust results in an alteration in alveolar macrophage metabolism of arachidonic acid that may promote an inflammatory reaction in lung tissue.

• Journal of the Korean Ceramic Society
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• v.35 no.6
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• pp.640-646
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• 1998

Nucleation and crystallzation of a quaternary glass system for lead titanate glass-ceramics were in-vestigated using DTA(differential thermal analysis ) with variation of nucleation temperature and crystal growth time. Glass samples containing 60mol% of PbO-{{{{ { TiO}_{2 } }} were prepared from melts by the conventional normal cooling method in a cylindrical brass mould. The glass sample was nucleated between 40$0^{\circ}C$ and 50$0^{\circ}C$ for a given time and showed the maximum nucleation rate at 46$0^{\circ}C$ The DTA crystallization peak temperature decreased with increasing nucleating time and decreasing heating rate during DTA runs which indicated an increase of the number of nuclei produced in the system.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2002.05b
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• pp.163-167
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• 2002

$TiO_2$ 고정화 지지체를 이용한 유기인계농약의 광분해에 대한 연구 결과 다음과 같은 결론을 얻을 수 있었다. Chlorpyrifos의 광분해 제거효율을 초기 pH 9에서는 반응시간 200분만에 완전 분해되었으며, 초기 pH 7, 5에서는 각각 반응시간 240분, 260분만에 완전히 분해되었다. 또한 Diazinon인 경우 초기 pH 9에서는 반응시간 200분만에 완전 분해되었으며, 초기 pH 7, 5에서는 각각 반응시간 220분, 240분만에 완전히 분해되었다. Chlorphyrifos와 Diazinon은 pH가 증가할수록 즉 산성에서 염기성쪽로 갈수록 반응속도가 증가하는 것을 볼 수 있었다.

• Microbiology and Biotechnology Letters
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• v.20 no.4
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• pp.459-469
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• 1992

The immobilization characteristics of Zymomonas mobilis for ethanol production were examined. Four different strains of Zymomonas mobilis have been used for ethanol production. Among those, Zymomonas mobilis KCTC 1534 has been selected as the best strain for the highest ethanol productivity from glucose and sucrose. The optimum temperature and pH of the selected strain for ethanol production were $37^{\circ}C$ and 5.0 respectively for both free and immobilized cells. When the cells were immobilized by the gel entrapment method, the immobilized cells could produce ethanol at a little higher temperature than free cells. Calcium alginate was selected as the best gel for immobilizing cells. The immobilized cells could maintain the viability of 80% in 10 weeks storage at $4^{\circ}C$ in the medium with 2% calcium chloride. 20-25 hours of preincubation in 10% glucose solution was required for the activation of immobilized cells entrapped within calcium alginate gel.