• Polymer(Korea)
• /
• v.27 no.5
• /
• pp.470-476
• /
• 2003

In order to obtain high refractive plastic materials, 1,2 -ethylenedisulfanylbis(2-mercaptomethyl-1-ethanthiol) (ESTT) was newly prepared in good yield by the reaction of 1,2-ethylenedisulfanylbis(2-bromomethyl-1-ethanthiol) (ESTB) with thiourea followed by hydrolysis using an aqueous ammonia solution and characterized by $^1$H-NMR (-SH at 1.7 ppm), $\^$13/C-NMR(-CH$_2$SH at 28.4 ppm) and FT-IR (-SH at 2540 cm$\^$-1/) spectroscopy, etc. Polythiourethanes (PTU) were obtained from the combinations of ESTT with each of 4,4＇-methylenebis(phenylisocyanate) (MDI), tolyene 2,4-diisocyanate (TDI), isophorone diisocyanate (IPDI), mxylene diisocyanate (XDI), and 1,6-diisocyanatohexane (HMDI) in the presence of dibutyltin dilaurylate as a catalyst, in a casting mold, and characterized by FT-IR (existence of N=C=O) spectroscopy and elemental analyzer (sulfur content). Accordingly, their thermal, mechanical and optical properties were investigated by using DSC, TGA, hardness tester and refractometer: both the melting point on DSC and crystallinity on X -ray diffraction (XRD) for specimens of PTUs were not observed. PTUs with T$\_$g/s above 110 $^{\circ}C$ showed good hardness (Shore D) in the range of 86 to 89. Thermal stabilities of PTUs obtained by using ESTT and each of diisocyanates containing aromatic rings were especially good. Also, the optical transmittances of amorphous PTUs through UV-visible source in the range of 400 to 600 nm were good. PTUs showed refractive indexes above 1.60, and their refractive indexes gradually increased with increase of sulfur contents.

• Polymer(Korea)
• /
• v.38 no.3
• /
• pp.351-357
• /
• 2014

In membrane covered stent, occlusion and fracture from membrane degradation by gastric acid sometimes occurred. Therefore, we investigated the physical properties of membrane covered stent according to its ingredient and concentration in gastric acid environment. Membrane covered stents consisted of silicone and polyurethane with 15%, 18%, 20% concentrations were used. After incubating stents in a condition of pH 1.2, we checked any changes at every 3 weeks for 18 weeks. The changes of membrane surface, radial expansion and recovery force of stent were investigated. Coating thickness increased proportionally to an increase in ingredient concentration. Surface was evenly coated with silicone compared to the case with polyurethane and its homogeneity was excellent in a high concentration. Degradation was much severe in the case of polyurethane. The radial force of silicone was higher than polyurethane, and the decrease of radial and recovery force was higher in the case of polyurethane. In conclusion, high concentration of silicone membrane was more stable than polyurethane in acid environment of in vitro study.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.38 no.3
• /
• pp.372-376
• /
• 2009

Physicochemical changes in persimmon were examined during natural organic acid fermentation. Major organic acids in raw persimmon juices were lactic acid (980 mg%) and acetic acid (245 mg%). The content of acetic acid was continuously increased during the whole period of fermentation up to 3 years. Glucose was the dominant free sugar, but the content was decreased after 20 days of fermentation. Most of the glucose was converted to ethanol until 40 days after initiation of acid fermentation. L- and a values of Hunter's color in fermented persimmon juice, which was naturally exuded from persimmon fruit as fermentation continued, increased gradually, while b value decreased. Acetic acid (1584 mg%) was the most abundant organic acid followed by lactic acid (712 mg%) and citric acid (48 mg%) in a persimmon fruit juice after completion of 3 year fermentation. A minute amount of residual free sugars, mainly glucose, even after 3 years of fermentation may cause changes in quality characteristics while storage for edible use.

• Clean Technology
• /
• v.14 no.3
• /
• pp.204-210
• /
• 2008

A series of $V_{2}O_{5}-TiO_2$ xerogel catalysts were prepared by nonhydrolytic sol-gel method and analysed by various characterization techniques. These catalysts showed much higher surface areas and total pore volumes than conventional V$V_{2}O_{5}-TiO_2$ xerogel and impregnated $V_{2}O_{5}/TiO_2$ catalysts. It was found that the textural property of $V_{2}O_{5}-TiO_2$ material varies with the method and conditions of synthesis. Surface vanadates and $TiO_2$ anatase phase are the crucial factors to obtain high catalytic activities. The selective oxidation of hydrogen sulfide in the presence of excess water and ammonia was studied over these catalysts. Xerogel catalysts prepared by non-hydrolytic sol-gel method showed very high conversion of $H_{2}S$ without harmful emission of $SO_2$. The highest catalytic activity shown by these $V_{2}O_{5}-TiO_2$ catalysts may be due to their high surface area and good dispersion of vanadia species in the titania matrix.

• Membrane Journal
• /
• v.28 no.2
• /
• pp.121-128
• /
• 2018

Terpolymers, which are chemical compounds composed of three different chemical compounds, have rarely been utilized for gas separation membranes. In this study, we demonstrate a simple process to fabricate a composite membrane for $CO_2/N_2$ separation based on a terpolymer synthesized from poly(2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl] ethylmethacrylate)(PBEM), poly(oxyethylene methacrylate)(POEM), and methyl methacrylate (MMA) via free radical polymerization. A solution of the as-synthesized PBEM-PMMA-POEM was coated onto a microporous polysulfone (PSf) support to form a composite membrane. The successful polymerization and the characteristics and morphology of the membrane were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FE-SEM). The gas permeance and $CO_2/N_2$ selectivity of the PBEM-PMMA-POEM terpolymer membrane were measured at $25^{\circ}C$. A maximum $CO_2/N_2$ selectivity of 30.2 was obtained at a $CO_2$ permeance of 57.4 GPU ($1GPU=10^{-6}cm^3$(STP)/($s\;cm^2\;cmHg$)).

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

• Journal of Adhesion and Interface
• /
• v.11 no.2
• /
• pp.41-49
• /
• 2010

Furan-containing epoxide monomers (8, 9) were designed and synthesized as carbon-neutral, environment-friendly adhesion material. Bicyclic skeleton were constructed using the Diels-Alder reaction of furan and methyl acrylate, both readily accessible starting material from a biomass via bio-refinery process. After reduction of ester functionality, resulting hydroxyl moieties were coupled to epichlorohydrin to provide the epoxy-functionalized furanic monomers (8, 9). The structure of new furanic monomers was confirmed by $^1H$ and $^{13}C$ NMR spectroscopy. As UV-curable monomers, basic properties such as UV curing time and the extent of UV curing were evaluated by photo DSC. Photo-curing shrinkages were measured by linear variable differential transformer transducer (LVDT) and the effect of molecular structure on shrinkage was considered. In addition, new synthetic compounds showed the shear strength over 3 MPa when they were photo-cured between polycarbonate plates, which indicates these compounds are feasible to use as photo-curable adhesive materials.

• Journal of Life Science
• /
• v.28 no.11
• /
• pp.1369-1378
• /
• 2018

Prunus mume Siebold & Zucc., a member of the Rosaceae family (called Maesil in Korea), has been widely distributed in East Asia, e.g. Korea, Japan and China, and its fruit has been used as a traditional drug and health food. In this study, we evaluated physicochemical properties and physiological activities of condensed Prunus mume juice treated with pectinase (PJ). The values of total acidity, pH, sugar contents, turbidity moisture content of the PJ were 35.81%, 2.73, $54.36^{\circ}Brix$, 2.75 and 51.32%, respectively. The PJ had effective DPPH radical scavenging activity, reducing power effect, $H_2O_2$ scavenging activity and ${\beta}$-carotene bleaching effect. DPPH radical scavenging activities of PJ was 46.31%; their reducing power ($OD_{700}$) was 1.80; $H_2O_2$ scavenging activity of PJ was 91.62%; and ${\beta}$-carotene bleaching effect of PJ was 73.02%. Also, PJ showed effective levels of ${\alpha}$-glucosidase inhibition activity. The cell viability was measured by SRB assay. The PJ significantly decreased the cell viability of mouse melanoma cells (B16) and human melanoma cells (SK-MEL-2 and SK-MEL-28) in a dose-dependent manner, however, there was no effect on human keratinocyte HaCaT. In morphological study, PJ-treated SK-MEL-2 cells showed distorted and shrunken cell masses. Total polyphenol contents and total flavonoid contents of PJ were 588.31 mg% (gallic acid equivalent) and 860.45 mg% (rutin equivalent). The antiproliferative effect of PJ seems to be associated with the antioxidant activity of its flavonoid and polyphenol contents. In conclusion, PJ may be beneficial in development of a functional food material.

• Journal of Korean Society of Environmental Engineers
• /
• v.38 no.9
• /
• pp.504-512
• /
• 2016

In this study, we investigated the environmental impact of organic and conventional paddy by monitoring soil properties and water quality. We sampled and analyzed topsoil (0~15 cm), subsoil (15~30 cm), and water of organic and conventional paddy fields in Yongin and Anseong, South Korea. The statistical significance between groups was determined by Duncan's multiple range test. The results show that T-P concentrations in both topsoil and subsoil of Anseong paddy were higher than those of Yongin paddy. The significant difference of T-P between organic and conventional paddy was observed in Anseong but not in Yongin. T-N of organic paddy soil was lower than that of conventional paddy in both Anseong and Yongin region. Water content for subsoil of organic paddy in Anseong was significantly different from others, which is consistent with the results of silt-clay content. pH and EC of water in conventional paddy were higher than those in organic paddy. In Anseong, COD, T-P, and $PO_4-P$ concentration of conventional paddy were higher than those of organic paddy. The regression analysis presented that there were no significant relationship between soil properties and water quality data except T-N.

• Journal of the Korea Concrete Institute
• /
• v.27 no.3
• /
• pp.245-252
• /
• 2015

As people have more interest in environment-friendly structures recently, many researchers are actively researching non-sintered cement in Korea and other countries. Non-sintered cement shows various characteristics of its reaction products and hardeners, depending on the kind of alkali activators. Thus, this study manufactures ground granulated blast furnace slag based non-sintered cement binder by using circulating fluidized bed combustion ash, which is a kind of industrial byproduct, as a stimulant, and investigated its hardening characteristics and hydration, depending on the rate of circulating fluidized bed combustion ash. Besides, this study investigated its insulation property according to the weight lightening of non-sintered cement. As a result, ettringite and C-S-H were mainly formed in the hydration, and it was possible to manufacture a non-sintered cement hardener over 50 MPa. Lastly, it was possible to manufacture a non-sintered cement hardener in a thermal conductivity level of $0.127W/m{\cdot}K$ when the compressive strength was 10 MPa for weight lightening.