• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.1
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• pp.151-159
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• 2006

In these days, the importance of sludge treatment is emerging due to the London Convention, so this study was conducted to propose the alternatives for the improved sludge treatment on the organic wastewater and sewage sludge with JAR test and settling column equipped with stirrer. The minimum coagulant dosage to earn the optimum sludge settling efficiency resulted from 200mg/l and each critical sludge settling interface showed no distinct difference when PAC was dosed over 200mg/l. Accordingly, Clarification Rate(CR) with 200mg/l dosage was calculated to CR=(Ho-Ht) / Ho=1-0.4=0.6 because the critical sludge settling height stopped at 0.4. The settling velocity of sludge interface was decreased with the increase of MLSS concentration but rather increased with MLSS concentration over 1,000mg/l. This resulted from positive effect of interacted coagulation for floc formation by transfer to the zone of compressed settling when MLSS concentration increased over 1,000mg/l. The settling velocity of sludge interface showed $28.66{\times}10^{-3}/min$ for average settling velocity of sewage sludge which is 6.7 times higher than $4.25{\times}10^{-3}/min$ for average settling velocity of organic wastewater sludge. The increasing rate of CR for organic wastewater activated sludge was higher than that of settling velocity under 200mg/l of PAC dosage but settling velocity was higher than CR over 200mg/l of PAC dosage. However, in case of sewage sludge, the differential rate of CR was low when PAC dosage was increased but the settling velocity was suddenly increased with over 200mg/l dosage. Therefore coagulation effect was more efficient to MLSS settling velocity rather than SS removal effect in the supernatant.

• Biomedical Science Letters
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• v.3 no.2
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• pp.83-88
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• 1997

In septic patients, disseminated intravascula. coagulation (DIC) occurs frequently and is a pathologic condition associated with a variety of critical illness. DIC may complicate the already complex clinical situations and contribute to the high mortality. Nevertheless, its pathogenic mechanisms are not completely elucidated. Present study was prospectively designed to understand the pathogenetic mechanisms involved in the development of DIC. 15 rats were subjected to study and according to the aim, they were divided into three groups： group I, control (not treated-endotoxin, n=5)； group II (12 hours after endotoxin injection, n=5)； group III (24 hours after endotoxin injection, n=5). Experimental DIC was induced in rats by a bolus injection of endotoxin (1mg/kg, E. coli serotype 055:B5). Blood was collected by direct puncture of the heart. Platelet count, fibrinogen and plasminogen concentration, antithrombin III, D-dimer and complement components (C3 and C4) were measured in all subjects. In group II and III, there were apparent signs of DIC, including thrombocytopenia, decreased fibrinogen (but increase in group III), reduced C3 and antithrombin III, and elevated D-dimer. These data indicated that endotoxin might induce the activation of several pathways such as coagulation, fibrinolytic and complement cascade, causing DIC and subsequent multiple organ failures. Ultimately, the increased knowledge of the various pathogenetic mechanisms of coagulation activation and fibrinolysis in endotoxin-induced DIC may have prophylactic or therapeutic implications.

• Journal of the Korean Ceramic Society
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• v.39 no.1
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• pp.38-44
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• 2002

Dispersion stability of nano-sized rutile TiO$_2$powder with acicular typed primary particle produced by homogeneous precipitation process at low temperatures was studied in aqueous and non-aqueous media in the presence of various electrolytes. The zeta potential measurements have shown that the addition of electrolytes to aqueous and non-aqueous dispersion media leads to charge reversal on TiO$_2$particle surface. The electrostatic repulsive forces acting on between TiO$_2$particles dispersed in non-aqueous media were found to be significantly greater than that in aqueous media, which relate closely to the physical properties of the organic solvents, such as viscosities and dielectric constants. The pH values, the concentration of electrolytes and the valence of the ions have changed greatly the surface potential of TiO$_2$ particles and have governed the dispersion behavior of TiO$_2$particles virtually.