• Economic and Environmental Geology
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• v.51 no.2
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• pp.113-120
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• 2018

Radioactive cesium($^{137}Cs$) can be released into the environment through severe nuclear accidents such as the Chernobyl and Fukushima, The $^{137}Cs$ is one of major monitoring radionuclides due to its chemical toxicity, ${\gamma}$ radiation and long half-life($t_{1/2}=30.2yrs$). It has been known well that illite adsorb selectively and strongly the cesium due to frayed edge sites. The quantity of the FES in the illite could be controlled by weathering processes. Therefore, this study was modified illite samples through artificial weathering in the laboratory to increase sorption efficiency for cesium. Abundant interlayer cations(i.e., K, Ca) were eluted within 1 day, while Si and Al were gradually released from the crystal structure. In addition, broad peaks of XRD indicated the occurrence of chemical weathering. The cesium sorption distribution coefficients increased up to approximately 2 times after the weathering. These results suggested that sorption capacity of illite could be enhanced for cesium through artificial weathering under low temperature.

• Applied Biological Chemistry
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• v.36 no.6
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• pp.440-448
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• 1993

To utilize effectively fish skin wasted from fish processing, a dover sole skin gelatin was prepared by alkaline extraction method and the physico-chemical properties were examined. Conditions for the suitable pretreatment, extraction and decolorization for gelatin preparation from dover sole skin are as follows: the skin is limed with 1.0% calcium hydroxide solution at $5^{\circ}C$ for 4 days, washed thoroughly for 2 days with tap water, extracted with 5 volumes of water $(pH\;5.0{\sim}7.0)$ to dehydrated skin for 3 hours at $50^{\circ}C$, and then bleached with 3% activated carbon. Though dover sole skin gelatin was prepared under above conditions, physico-chemical property values such the melting point and gelling point of that were lower than those of yellowfin sole skin gelatin as well as the commercial pork skin gelatin. Therefore, the purified dover sole skin gelatin requires a suitable modification operation for better quality gelatin manufacture.

• Korean Journal of Environmental Agriculture
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• v.17 no.3
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• pp.246-253
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• 1998

Heavy metal-tolerant microorganisms, such as Pseudomonas putida, P. aeruginosa, P. chlororaphis and P. stutzeri which possessed the ability to accumulate cadmium, lead, zinc and copper, respectively, were isolated from industrial wastewaters and mine wastewaters polluted with various heavy metals. The binding sites of heavy metal in the cells were investigated by chemical modification of functional groups the cell walls. To determine the binding sites of heavy metal in the cells, electrochemical charge of amine and carboxyl groups in the cell walls of heavy metal-tolerant microorganisms were chemically modified. Chemical modifications of amine groups did not affect the heavy metal uptake as compared to native cell walls. In contrast, modifications of carboxyl groups drastically decreased heavy metal uptake as compared to native cell walls, and electron microscopy confirmed that the form and structure of the heavy metal uptake were different from those of native cell walls. The results suggested that the carboxyl groups were the major sites of heavy metal uptake in the heavy metal-tolerant microorganism cell.

• The Korean Journal of Pesticide Science
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• v.10 no.2
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• pp.149-152
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• 2006

Construction of focused library of 2-benzylimino-1,3-thiazolines 7 through molecular modification of 3-alkyl-2-phenylimino-1,3-thiazolines 1 which showed selective fungicidal activity against rice blast and their fungitoxic activity against 6 kinds of typical plant diseases was described. Fifty four compounds of focused library of 2-benzylimino-1,3-thiazolines 7 were synthesized from the reaction of the corresponding $\gamma$-chloroacetoacetanilides 6 with N-benzyl thioureas 5 by parallel synthetic methodology. As results of fungicidal screening against the typical plant diseases, twenty eight kinds of 7 at 100 ${\mu}g$ $mL^{-1}$ showed the control value over 50% against tomato late blight.

• The Korean Journal of Pesticide Science
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• v.7 no.1
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• pp.51-57
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• 2003

For the purpose of a development of new agrochemical fungicides, new compound 4 in which 1,3-thiazoline scaffold as well as urea moiety in the structure was designed through molecular modification of lead compound, 2-imino-1,3-thiazone based on isosterism. The reaction of N-alkylthiourea 5 and bromoacetonitrile in ethanol gave 2,4-diimino-1,3-thiazolidine hydrobromide 6 regioselectively, which was treated with isocyanates gave the corresponding 8 which is tautomer of 4. Antifungal screening (in vivo) of the synthesized compound 8 against typical plant diseases, which include rice blast, rice sheath blight, cucumber gray mold, tomato late blight, wheat leaf rust, and barley powdery mildew, was carried out. Antifungal activities against rice blast of the compound 8 were weaker than those of 2-phenylimino-1,3-thiazoline 1. Some compounds showed weak antifungal activities against wheat leaf rust.

• Membrane Journal
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• v.25 no.1
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• pp.15-26
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• 2015

In this study, porous metal (O.D. = 10 mm, length = 10 mm, 316 L SUS, Mott Corp.) and ${\alpha}$-alumina tube (O.D. = 10 mm, length = 50 mm, Pall, German) support was modified with suspension sols, which were consisted of $3{\sim}4{\mu}m$ and 150 nm size of ${\alpha}$-alumina particle in the water or silica-zirconia colloidal sol. The porous support was fabricated by dip coating method for 5 seconds with suspension of alumina particles. After drying at $100^{\circ}C$ for 1 h, it was calcined at $550^{\circ}C$ for 30 min. It was repeated several times in order to decrease big pore on support. The surface roughness and largest pore size on the porous support was decreased by increasing coating times with $3{\sim}4{\mu}m$ size of ${\alpha}$-alumina particle and alumina coating with 150 nm size of ${\alpha}$-alumina particle served as further smoothening the surface and decreasing the pore size of the substrate. And the silica-zirconia membranes were successfully prepared on the modified porous metal and ${\alpha}$-alumina supports, and showed hydrogen permeance in the range of $1.8-8.4{\times}10^{-4}mol{\cdot}m^{-2}{\cdot}s^{-1}{\cdot}Pa^{-1}$ and $3.3-5.0{\times}10^{-5}mol{\cdot}m^{-2}{\cdot}s^{-1}{\cdot}Pa^{-1}$, respectively.

• Journal of the Korean Chemical Society
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• v.39 no.3
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• pp.204-212
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• 1995

The graphite furnace atomic absorption spectrophotometric determination of trace lead in water samples was studied using matrix modifiers. In order to modify the sample matrix, the type and optimum amount of the modifier were investigated with a given concentration of Pb solution. In fact, if the matrix is not modified, lead has low ashing and atomization temperatures as to give a low absorbance with bad reproducibility because of its volatility. Therefore, optimum modifiers should be used to stabilize the atomization. In this work, the ashing and atomization temperatures were raised from 400 and $1800^{\circ}C$, to 1,000 and $2000^{\circ}C$, by the addition of palladium to 50 ng/mL lead solution as a modifier. The concentration of palladium was 5.0 ${\mu}g/mL$ in the modified solution. Furthermore, if 1.5 ${\mu}g/mL$ of aluminum was mixed with the palladium modifier as an auxiliary modifier, the ashing temperature could be increased $150^{\circ}C$ additionally. With such a treatment, the sensitivity was improved more than 5 times of the solution unmodified and the reproducible results of less than 5% RSD were obtained in the samples of university's waste water and pipe-washing tap water. It could be concluded that this procedure was quantitative in the determination of trace lead from the recoveries of more than 88% obtained in the samples in which a given amount of lead was spiked.

• Journal of the Korea Concrete Institute
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• v.28 no.3
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• pp.317-328
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• 2016

This research intends to understand the impact of super-absorbent polymer (SAP) as an internal curing agent in Ultra-High Performance Concrete (UHPC). Two different types of SAPs of acrylic acid (SAP_AA) and acrylic acid-co-acrylamide (SAP_AM) were examined with UHPC formulation. Isothermal calorimetry and x-ray diffraction experiments revealed the impact of polymers with the different chemical bonds on cement hydration. To test its feasibility as a shrinkage reducing admixture for UHPC, a series of experiments including flowability, compressive strength, rapid chloride permeability and autogenous shrinkage profile was performed. While both SAPs showed a reduction in autogenous shrinkage, it has been concluded that the SAP size and chemical form significantly affect the performance as an internal curing agent in UHPC by controlling cement hydration and porosity modification. Between the tested SAPs, SAP_AM which absorbs more water in UHPC than SAP_AA, shows better mechanical and durability performance.

• Applied Chemistry for Engineering
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• v.18 no.2
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• pp.99-110
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• 2007

Efficient and inexpensive hydrogen storage is an essential prerequisite for the utilization of hydrogen, one of the new and clean energy sources for $21^{st}$ century. In this review, several storage techniques are briefly reviewed and compared. Especially, adsorption/storage via physisorption at low temperature, by using nanoporous adsorbents, is reviewed and evaluated for further developments. The adsorption over a porous material at low temperature is currently investigated deeply to fulfill the storage target. In this review, several characteristics needed for the high hydrogen adsorption capacity are introduced. It may be summarized that following characteristics are necessary for high storage capacity over porous materials: i) high surface area and micropore volume, ii) narrow pore size, iii) strong electrostatic field, and iv) coordinatively unsaturated sites, etc. Moreover, typical results demonstrating high storage capacity over nanoporous materials are summarized. Storage capacity up to 7.5 wt% at liquid nitrogen temperature and 80 atm is reported. Competitive adsorbents that are suitable for hydrogen storage may be developed via intensive and continuous studies on design, synthesis, manufacturing and modification of nanoporous materials.

• Korean Journal of Food Science and Technology
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• v.25 no.6
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• pp.716-723
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• 1993

To utilize effectively fish skin wasted from fish processing, a yellowfin sole skin gelatin was prepared by alkaline extraction method and the physico-chemical properties were examined. Conditions for the suitable extraction and decolorization for gelatin preparation from yellowfin sole skin are as follows: the skin is limed with 1.5% calcium hydroxide solution at $5^{\circ}C$ for 5 days, washed throughly with tap water, extracted with 6 volumes of water ($pH5.0{\sim}7.0$) to dehydrated skin for 3 hours at $50^{\circ}C$, and then bleached with 3% activated carbon. Though yellowfin sole skin gelatin was prepared under above condition, the physico-chemical property values such the melting point and gelling point of that were lower than those of pork skin gelatin. Therefore, the purified yellowfin sole skin gelatin requires a suitable modification operation for more a good quality gelatin manufacture.