• Proceedings of the Korean Vacuum Society Conference
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• 1993.02a
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• pp.3-3
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• 1993

• Proceedings of the Korean Vacuum Society Conference
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• 1996.02a
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• pp.181-181
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• 1996

• Journal of Ecology and Environment
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• v.36 no.1
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• pp.73-83
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• 2013

The object of this study was to evaluate lotic ecosystem health using multiple eco-metric approaches such as water chemistry diagnosis, physical habitat health evaluations, and biological integrity modeling at 100 streams of four major watersheds. For the study, eight chemical water quality parameters such as nutrients (N, P) and organic material were measured and 11-metric models of Qualitative Habitat Evaluation Index (QHEI) and multiple eco-metric health assessment model (MEHA) were applied to the four major watershed. Nutrient analysis of nitrogen (N) and phosphorus (P) in all watersheds indicated a eutrophic state depending on the locations of sampling streams. Physical habitat health, based on the QHEI model, averaged 114 (range: 56 - 194), judging as a "good condition" by the criteria of Plafkin et al. (1989). In addition, primary (H1 - H4), secondary (H5 - H7), and tertiary habitat metric variables (H8 - H11) were analyzed in relation to the physical habitat degradations. The plots of tolerant species ($P_{TS}$) and sensitive species ($P_{SS}$) to water quality showed that the proportions of $P_{TS}$ had positive linear functions with nutrients, and that the $P_{SS}$ had inverse linear relations with the chemical variables. The model of eco-metric health assessment showed that mean MEHA was 20.4, indicating a fair condition. Overall, our data suggest that water chemistry, based on nutrients and organic matter, directly modified the trophic structures in relation to food chain in the aquatic ecosystems, and then these directly influenced the compositions of tolerance/sensitive species, resulting in degradations of overall ecological health.

• Journal of the Korean Chemical Society
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• v.47 no.2
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• pp.155-164
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• 2003

This study examined the types of explanations related to physical change and chemical change in the science textbooks of middle and high school based on the prior study of science teachers' understanding. For this research, the researchers analyzed 44 textbooks of middle school science and high school chemistry. As a result, there were no explanation or property type explanation represented in most of the textbooks related to physical and chemical change concepts. Also, there are few relationship represented between physical change and chemical change, and the examples related to physical change and chemical change were confused. These representations of textbooks can give rise to confusion of understanding of teachers and learners. So, it needs to re-design the explanation types correctly and constantly in science textbooks related to physical change and chemical change.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.5
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• pp.503-509
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• 2016

To identify causes for drastic decrease in yield of tomato with repeated culturing number of the bag culture substrate of greenhouse tomatoes we investigated the physical and chemical properties of a coir used as the bag culture substrate to grow tomato at the Booyeo tomato experimental institute located in Booyeo, Chungnam Province for three years from 2012 to 2014. The results showed that total porosity ranged from 65.4 to 73.1% for the bulk densities of coir ranging from 0.12 to $0.14g\;cm^{-3}$. The volumetric water contents measured at 0.01 bar as air entry point were 25% (before), 33% ($1^{st}yr$), 45% ($2^{nd}yr$), and 37% ($3^{rd}yr$). Organic matter contents ranged from 82.0 to 96.2% (highest in $1^{st}yr$). pH and EC ranged from 4.47 to 6.47 (highest in $2^{nd}yr$), and from 22.2 to $53.5dS\;m^{-1}$ (highest in $1^{st}yr$) and cation exchange capacity ranged from 71.0 to $191.7cmol\;kg^{-1}$ (highest in $3^{rd}yr$). The surface structure observed with electrical microscope showed that the number of large pores decreased with increasing cultivating time while the proportion of smaller pores increased, indicating that the coir was consistently decomposed. Therefore, we could conclude that these changes of all physical and chemical properties of the coir may influence the holding capacities of water and nutrients, resulting in deterioration of quality of culture substrate of greenhouse tomatoes.

• Bulletin of the Korean Chemical Society
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• v.24 no.6
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• pp.843-852
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• 2003

We present a brief account of the theory of diffusion-influenced kinetics of reactions involving polymers. The review will be based on the recent contributions from the authors. Both intrapolymer and interpolymer reactions are considered, and the effects of various physical factors, such as the chain length, chain stiffness, and hydrodynamic interactions, are described within a unified theoretical framework.

• Macromolecular Research
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• v.15 no.1
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• pp.17-21
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• 2007

A series of new, vinyl sulfone-containing monomers was prepared by p-aminophenyl vinyl sulfone (1) with various acid chlorides such as adipoly chloride, terephthaloyl chloride and isophthaloyl chloride. Finally, tertiary amine-containing poly(amide-sulfone)s were prepared by the Michael-type addition polymerization using N,N-dimethylethylenediamine (DMEDA), p-phenylenediamine and piperazin. To evaluate the relevant properties for permselective membranes and enzyme substrate, various physical properties such as molecular weight, solubility, quaternization behavior and thermal properties were examined.

• Applied Chemistry for Engineering
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• v.16 no.3
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• pp.342-347
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• 2005

Photocurable hyperbranched acrylates were prepared from acrylic acid and hyperbranched polyol (HBP-16, 32, 64). Physical properties of three kinds of photocurable hyperbranched acrylated were investigated. Thermal stability of UV cured film measured by TGA shifted to higher temperature with increasing of functionality. Hardness, abrasion resistance, and tensile strength of UV cured film also increased with increasing functionality of acrylate. Weathering test for UV cured film showed the value of yellow index increased with increasing functionality of acrylate.

• Journal of Integrative Natural Science
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• v.4 no.3
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• pp.182-186
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• 2011

Chemical modification of porous silicon surface has been investigated to have different physical surface properties. Porous silicon modified with dodecyl functionality exhibits hydrophobic feature, however the oxidation of porous silicon to modify with hydroxyl group displays hydrophilic properties. Surface characterization for both dodecyl and hydroxyl derivatized porous silicon was investigated by FT-IR spectroscopy. To determine the surface coverage, the amine functionalized surface was reduced by dithiothreitol (DTT) and the released 2-thiopyridone was quantified by UV/vis spectroscopy.

• Journal of Integrative Natural Science
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• v.4 no.3
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• pp.187-191
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• 2011

The differences of properties for both single-layered and multi-layered porous silicon were investigated. Multistructured porous silicons such as DBR or rugate porous silicon exhibit strong reflection resonances providing the reflection of a specific wavelength in the optical reflectivity spectrum. DBR PSi displays a square varying porosity gradient in the direction perpendicular to the plane of the filter but a sinusoidally varying porosity gradient was obtained for rugate PSi.