• Geomechanics and Engineering
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• 제1권4호
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• pp.291-306
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• 2009

One-dimensional soil-column studies were carried out to understand the interaction of three industrial effluents namely amino acid ('highly acidic'), surfactant ('highly organic') and pharmaceutical ('organic and toxic') on the physicochemical behavior, index properties and shear strength of bentonite due to artificial contamination extending to nearly 300 days. Changes in inorganic and organic pollutants present in the effluents due to the interaction of the above effluents and soil were assessed to understand the physico-chemical behaviour. Batch and continuous modes of operation, 8 hrs and 16 hrs Hydraulic Retention Time [HRT] and 25%, 50% concentrations of effluents, were the parameters considered. Amino acid, surfactant and pharmaceutical effluents have shown a high variation in pH (7 to 8) after artificial contamination on bentonite that is their original characteristics of the above effluents have been completely reversed. Further, it is found that the shear strength of bentonite has reduced by about 20%, and with respect to liquid limit and plastic limit shows an increasing trend with time within the period of contamination.

• Bulletin of the Korean Chemical Society
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• 제34권7호
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• pp.2086-2092
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• 2013

Two new high-nitrogen energetic compounds $ZTO{\cdot}2H_2O$ and $ZTO(phen){\cdot}H_2O$ have been synthesized (where ZTO = 4,4-azo-1,2,4-triazol-5-one and phen = 1,10-phenanthroline). The crystal structure, elemental analysis and IR spectroscopy are presented. Compound 1 $ZTO{\cdot}2H_2O$ crystallizes in the orthorhombic crystal system with space group Pnna and compound 2 $ZTO(phen){\cdot}H_2O$ in the triclinic crystal system with space group P-1. In $ZTO(phen){\cdot}H_2O$, there is intermolecular hydrogen bonds between the -NH group of ZTO molecule (as donor) and N atom of phen molecule (as acceptor). Thermal decomposition process is studied by applying the differential scanning calorimetry (DSC) and thermo thermogravimetric differential analysis (TG-DTG). The DSC curve shows that there is one exothermic peak in $ZTO{\cdot}2H_2O$ and $ZTO(phen){\cdot}H_2O$, respectively. The critical temperature of thermal explosion ($T_b$) for $ZTO{\cdot}2H_2O$ and $ZTO(phen){\cdot}H_2O$ is $282.21^{\circ}C$ and $195.94^{\circ}C$, respectively.

• 대한금속재료학회지
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• 제49권8호
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• pp.596-600
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• 2011

Thermal degradation behavior of a $WO_3-TiO_2$ monolithic catalyst was investigated in terms of structural, morphological, and physico-chemical analyses. The catalyst with 4 wt.% $WO_3$ contents were prepared by a wet-impregnation method, and a durability test of the catalysts were performed in a temperature range between $400^{\circ}C$ and $800^{\circ}C$ for 3 h. An increase of thermal stress decreased the specific surface area, which was caused by grain growth and agglomeration of the catalyst particles. The phase transition from anatase to rutile occurred at around $800^{\circ}C$ and a decrease in the Brønsted acid sites was confirmed by structural analysis and physico-chemical analysis. A change in Brønsted acidity can affect to the catalytic efficiency; therefore, the thermal degradation behavior of the $WO_3-TiO_2$ catalyst could be explained by the transition to a stable rutile phase of $TiO_2$ and the decrease of specific surface area in the SCR catalyst.

• 한국환경농학회지
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• 제31권1호
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• pp.75-95
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• 2012

BACKGROUND: Increase of heavy metals in agricultural ecosystem has become a social issue nationwide as it is related to public health. This review was performed to find out more systematic and integrated future researches on heavy metals using up to date articles published in the Korean journals related to agricultural environment. METHODS AND RESULTS: Researches on heavy metals in agricultural soils and plant uptake were categorized by the establishment of criteria, analytical methods, monitoring, management of source, characteristics and behavior in soil, plant uptake, bioavailability affecting physico -chemical properties in soil, risk assessment and soil remediation. In the early 1990s, the monitoring for heavy metals in soil has been widely performed. Accumulation of heavy metals in contaminated soil and availability to plants has also attracted interests to study the soil remediation using various physico-chemical methods. The phytoavailability and phytotoxicity of heavy metals have been mainly studied to assess the safety of agro-products using risk assessment techniques in the 2000s. CONCLUSION: Future direction of research on heavy metal in agricultural environment must be carried out by ensuring food safety and sustainability. A steady survey and proper management for polluted regions should be continued. Law and regulation must be modified systematically. Furthermore, studies should expand on mitigation of heavy metal uptake by crops and remediation of polluted fields.

• 한국축산시설환경학회지
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• 제1권2호
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• pp.155-164
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• 1995

Despite considerable progresses made in our understanding of environmental fate of pollutants stemming from animal production systems, relatively little is known about the processes and mechanisms regulating their dispersement (via emission) into and deposition from the earth's atmospheric system. Here we present and summarize up-to-date knowledge on this topic with a main emphasis on their origin, physico-chemical characteristics, and geochemical distribution behavior.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.592-595
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• 2002

New polymeric hydrogels based on vinyl ethers have been synthesized by the ${\gamma}$-initiated polymerization method. Their physical chemistry and physical mechanical properities have been studied. It has been shown that structure and swelling behavior of the hydrogels can be regulated by the changing of synthesis conditions nature of monomers. Novel stimuli-sensitive polymers have been synthesized by the varying of macrochains hydrophilic-hydrophobic balance. The some biomedical aspects of application of hydrogels in capacity of drain aging polymeric materials in ophthalmology surgery, implants in plastic surgery as well as drug delivery systems have been investigated.

• Computers and Concrete
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• 제4권4호
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• pp.273-284
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• 2007

The paper considers a theoretical model for the study of the process of transfer of sulfate ions in saturated porous media - mineral composites. In its turn, the model treats diffusion of sulfate ions into cement based composites, accounting for simultaneous effects such as filling of micro-capillaries with ions and chemical products and liquid push out of them. The proposed numerical algorithm enables one to account for those simultaneous effects, as well as to model the diffusive behavior of separate sections of the considered volume, such as inert fillers. The cases studied illustrate the capabilities of the proposed model and those of the algorithm developed to study diffusion, considering the specimen complex configuration. Computations show that the theoretical assumptions enable one to qualitatively estimate the experimental evidence and the capabilities of the studied composite. The results found can be used to both assess the sulfate corrosion in saturated systems and predict and estimate damage of structures built of cement-based mineral composites.

• Macromolecular Research
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• 제14권5호
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• pp.530-538
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• 2006

There are three important components in tissue engineering: the cells, signaling factors (cytokines and growth factors), and scaffolds. To obtain finely engineered tissue, all three components should perform their individual functions and be fully integrated with each other. For the past few years, we have studied the characteristics of photodimerizable HA (CHA)/alginate (CA) composite materials. CHA/CA complex hydrogels, which were irradiated under UV light and, then treated with calcium ions, were found to have good biocompatibility, mechanical properties and water resistance for implantable tissue scaffolds. In this study, we introduced a cell growth factor (basic fibroblast growth factor; bFGF) into the CHA/CA scaffolds and studied its release behavior. We also introduced tetracycline hydrochloride and flurbiprofen into the same scaffolds as model activation factors and evaluated their release behaviors from the scaffolds. The drug release rate from the materials was influenced by various parameters, such as the degree of crosslinking, the cross linker type, the physico-chemical properties of the drug, and the amount of the drug in the polymer. The results indicated that the negatively charged CHA/CA composite materials showed sustained release behavior and that HA has a particularly strong negative charge, making it attractive toward tetracycline hydrochloride and bFGF, but repulsive toward flurbiprofen.

• Archives of Pharmacal Research
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• 제10권2호
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• pp.94-99
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• 1987

By using the former equation (8), we modified the equation which can show the dissimilar osmotic behavior of liposome with composition change. The slope of the new equation was presented as the ratio of osmotically active volume (V$_{act}$= ) to the total volume (V$_{totel}$= $_{acl}$+ V$_{dead}$ ; V$_{dead}$ is osmotically inactive volume) of loposomes, we defined is as a Z-value, which can elucidate the dissimilarity of the osmotic activity of multilamellar liposomes with the change of phospholipid composition and the differences of physicochemical properties of liposomes. Z-value was applied for studying the physico-chemical properties of liposomal membrane. The factor that affects on the Z-value was not the lipid concentration of liposome stock dispersion but the lipid composition of liposomal membrane. As the content of dicetylphosphate, the negative charged phospholipid, was increased, the osmotic activity, represented by Z-value, of multilamellar liposome was decreased. Using the hypertonic conditions (shrinking region), Z-value steadily increased and reached a maximum at 10 mole percent cholesterol with increasing the cholesterol content.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.129.2-129.2
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• 2010

AEM which were used for solid alkaline fuel cell(SAFC) were prepared by photo polymerization in method pore-filling with various quaternary ammonium cationic monomers and crosslinkers without an amination process. Their specific thermal and chemical properties were characterized through various analyses and the physico-chemical properties of the prepared electrolyte membranes such as swelling behavior, ion exchange capacity and ionic conductivity were also investigated in correlation with the electrolyte composition. The polymer electrolyte membranes prepared in this study have a very wide hydroxyl ion conductivity range of 0.01 - 0.45S/cm depending on the composition ratio of the electrolyte monomer and crosslinking agent used for polymerization. However, the hydroxyl ion conductivity of the membranes was relatively higher at the whole cases than those of commercial products such as A201 membrane of Tokuyama. These pore-filling membranes have also excellent properties such as smaller dimensional affects when swollen in solvents, higher mechanical strength, lowest electrolyte crossover through the membranes, and easier preparation process compared of traditional cast membranes. The prepared membranes were then applied to solid alkaline fuel cell and it was found comparable fuel cell performance to A201 membrane of Tokuyama.