• Journal of Soil and Groundwater Environment
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• v.15 no.3
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• pp.34-43
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• 2010

The fate of hydrophobic organic contaminants (HOCs) in ground water is highly affected by the distribution and property of the carbonaceous materials (CMs) in subsurface sediments. CMs in soils consist of organic matters (e.g., cellulose, fulvic acid, humic acid, humin, etc.) and black carbon such as char, soot, etc. The distribution and property of CMs are governed by source materials and geological evolution (e.g., diagenesis, catagenesis, etc.) of them. In this study, the distribution and property of CMs in subsurface sediments near the Imjin river in the Republic of Korea and HOC sorption property to the subsurface sediments were investigated. The organic carbon contents of sand and clay/silt layers were about 0.35% and 1.37%, respectively. The carbon contents of condensed form of CMs were about 0.13% and 0.45%, respectively. The existence of black carbon was observed using scanning electron microscopes with energy dispersive spectroscopy. The specific surface areas (SSA) of CMs in heavy fraction(HFrCM) measured with N2 were $35-46m^2/g$. However, SSAs of those HFrCM mineral fraction was only $1.6-4.3m^2/g$. The results of thermogravimetric analysis show that the mass loss of HFrCM was significant at $50-200^{\circ}C$ and $350-600^{\circ}C$ due to the degradation of soft form and condensed form of CMs, respectively. The trichloroethylene (TCE) sorption capacities of sand and clay/silt layers were similar to each other, and these values were also similar to oxidzed layer of glacially deposited subsurface sediments of the Chanute Air Force Base (AFB) in Rantoul, Illinois. However, these were 7-8 times lower than TCE sorption capacity of reduced layer of the Chanute AFB sediments. For accurate prediction of the fate of hydrophobic organic contaminants in subsurface sediments, continuous studies on the development of characterization methods for CMs are required.

• Restorative Dentistry and Endodontics
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• v.42 no.1
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• pp.9-18
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• 2017

Objectives: This study evaluated color differences (${\Delta}Es$) and translucency parameter changes (${\Delta}TPs$) of various computer-aided design/computer-aided manufacturing (CAD/CAM) blocks after immersion in coffee. Materials and Methods: Eight CAD/CAM blocks and four restorative composite resins were evaluated. The CIE $L^{\ast}a^{\ast}b^{\ast}$ values of 2.0 mm thick disk-shaped specimens were measured using the spectrophotometer on white and black backgrounds (n = 6). The ${\Delta}Es$ and ${\Delta}TPs$ of one day, one week, and one month immersion in coffee or water were calculated. The values of each material were analyzed by two-way ANOVA and Tukey's multiple comparisons (${\alpha}=0.05$). The ${\Delta}Es$ after prophylaxis paste polishing of 1 month coffee immersion specimens, water sorption and solubility were also evaluated. Results: After one month in coffee, ${\Delta}Es$ of CAD/CAM composite resin blocks and restorative composites ranged from 1.6 to 3.7 and from 2.1 to 7.9, respectively, and ${\Delta}TPs$ decreased. The ANOVA of ${\Delta}Es$ and ${\Delta}TPs$ revealed significant differences in two main factors, immersion periods and media, and their interaction except for ${\Delta}Es$ of TEL (Telio CAD, Ivoclar Vivadent). The ${\Delta}Es$ significantly decreased after prophylaxis polishing except GRA (Gradia Block, GC). There was no significant correlation between ${\Delta}Es$ and water sorption or solubility in water. Conclusions: The ${\Delta}Es$ of CAD/CAM blocks after immersion in coffee varied among products and were comparable to those of restorative composite resins. The discoloration of CAD/CAM composite resin blocks could be effectively removed with prophylaxis paste polishing, while that of some restorative composites could not be removed.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2003.06a
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• pp.185-185
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• 2003

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2003.06a
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• pp.184-184
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• 2003

• Economic and Environmental Geology
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• v.40 no.4
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• pp.361-374
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• 2007

Rare earth elements(REEs) have been used as an useful tool in understanding the various geological processes such as evolution and differentiation in the crust. The REEs also have been used as an analog of actinides for radioactive wastes at the water-rock interactions. Using physicochemical properties of the REEs and actinides, we have shown that Eu is an optimum analogue for understanding the behavior of Am in subsurface environments. Factors affecting sorption behavior of radioactive nuclides in groundwater were investigated by batch experiments. Four nuclides such as $^{241}Am,\;^{152}Eu,\;^{160}Tb\;and\;^{60}Co$ were selected to test our hypothesis, and $^{160}Tb$ and $^{60}Co$ were specifically used to compare to the sorption behavior between $^{241}Am-^{152}Eu$ and other radioactive nuclides. Four different rock samples and one groundwater were used in the batch experiments where solution pH for all experiments was fixed at 5.5. Our results demonstrate that $^{241}Am,\;^{152}Eu,\;and\;^{160}Tb$ show similar sorption behavior whereas $^{60}Co$ is different in sorption behavior at the mineral-water interface, suggesting that the sorption behavior of $^{60}Co$ is affected by different rock types. Our results also show that 1) Eu in REEs is optimum analogue of fate and transport of Am in subsurface environments, and 2) mineral compositions such as $SiO_2,\;TiO_2,\;P_2O_5$ and distribution of REEs such as Eu anomaly play key roles in affecting sorption behavior of radioactive nuclides even though physicochemical properties of geological materials such as specific surface area and cation exchange capacity can not be ruled out.

• Journal of the Korean Society of Clothing and Textiles
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• v.18 no.1
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• pp.113-120
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• 1994

The Purpose of this study was to improve the moisture related properties of viscose rayon fibers. Viscose rayon filament yarns were partially etherified to make CMC fibers. CMC fibers were converted to the sodium, calcium, and ferric salt forms by an ion exchange method. The property changes of ion exchanged CMC fibers were examined. Cation contents of fibers were varied depending on the degree of substitution of CMC fibers. The strength of Na, Ca, Fe-CMC was higher than H-CMC owing to the plasticization by moisture sorption and the crosslinking by cations. The moisture regain was increased by carboxymethylation and that of Fe-CMC showed the highest value. The degree of swelling determined by the water retention value was observed to be Na-CMC > Ca-CMC > H-CMC > Fe-CMC. The solution retention value was decreased in the order . Ca-CMC > Na-CMC > H-CMC > Fe-CMC.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.543-550
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• 1999

Hazardous substances produced from industrial sectors have caused serious contamination of soils and groundwater. The hydrophobic organic compounds in the subsurface are hard to be decomposed, and as they soil on the soil or last as a NAPL they might contaminate the groundwater for a long time. Although we recognize the danger of contaminated subsurface, very little was known about the effective remediation technique. This paper focuses on the remediation of the p-Cresol which contaminated subsurface by applying the surfactant-enhanced description technique. Sorption characteristics of soils and organic compounds are studied, and the applications of surfactant solution are studied for effective rededication. The results from this study could be used as some data for surfactant-enhanced rededication. The flexible-wall permeameter tests are performed in which in-situ remediation is simulated. Results show that triton X-100 at 2% solution disrobes p-Cresol 1.7 times as much as water description in the flexible-wall permeameter tests.

• Journal of the Korean Wood Science and Technology
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• v.19 no.4
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• pp.27-33
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• 1991

Three kinds of specimens(radiata pine sapwood, radiata pine heartwood and whemlock heartwood) were dried at four temperature levels (30, 40, 50 and $60^{\circ}C$) in an emvironmental chamber. Unsteady-state diffusion coefficients were calculated from obtained drying fates by using infinite slab equation for first half of sorption and interval diffusion equation for second half of sorption. Activation energies for moisture diffusion in wood were calculated from the diffusion coefficients obtained at four temperatures. In most cases diffusion coefficients for radial movement were higher than those for tangential movement. Activation energy differences between sapwood and heartwood weren't significant for radial movement, but were significant for tangential movement. Most activation energies calculated from drying rates were lower than heat of water condensation(about 11,000cal/mole). Specially the avenge activation energy for sapwood tangential movement was only 5,000cal/mole.

• Journal of the East Asian Society of Dietary Life
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• v.14 no.5
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• pp.457-462
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• 2004

Physical properties of soybean curd powder prepared with hot air, vacuum and freeze drying methods were investigated. Adsorption characteristics were studied under various water activities (such as 0.11, 0.33, 0.44, 0.55, 0.66, 0.75, 0.85, and 0.93) at 5℃, and prediction models were developed. Equilibrium moisture and monolayer moisture contents were the highest when freeze dried. due to the porous structure. In this result, Oswin model was the best fit for the isotherm of soybean curd. Sorption enthalpy indicated that high moisture content of powder showed lower sorption than that of low moisture content.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.1
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• pp.53-60
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• 2005

Ferrous cement hydrates made from hydrating Portland cement doped with Fe (II) were reported to reductively dechlorinate chlorinated organics and to reduce Cr (VI) to Cr (III). In this study, kinetics of nitrate removal by ferrous cement hydrates were investigated. Nitrate removal kinetics were characterized by experimental variables such as cement hydration, amount of cement addition, Fe (II) dose, pH, and byproducts. As a result, hydrated cement showed better performances than non-hydrated cement due to the formation of LDH (layered double hydroxide). Doping of Fe (II) into the cement was found to improve removal efficiency at high pHs by association with Fe (II) sorbed on cement hydrates as a reactive reductant. Reduction of nitrate produced ammonium as a major product, which accounted for 63.5% of the final products, and nitrite (0.15%) as a minor product. These results indicate that the developed media are effective as sorbent/reducing agents in the nitrate removal and the reaction mechanisms of nitrate removal are sorption and reduction.