• Elastomers and Composites
• /
• v.21 no.4
• /
• pp.323-346
• /
• 1986

• Korean Journal of Food Science and Technology
• /
• v.15 no.2
• /
• pp.189-194
• /
• 1983

Raw and extruded barleys prepared by three different conditions were powdered and stored for four months at ambient $(25^{\circ}C)$ and accelerated temperatures $(40^{\circ}C)$ with $A_w$ of 0.31 and 0.71, respectively. The stability of the these samples with respect to lipid oxidation was studied. The lipid oxidation of all samples, as measured by the lipid diene conjugation of the extracted oil, increased with increased $A_w$ and temperature and with the storage time elapsed. The ratio of unsaturated to saturated fatty acids (U/S ratio) tended to decreased as the $A_w$ and temperature were increased. The raw sample had a greater increase in lipid conjugation diene but a decrease in U/S ratio than the extruded samples. The extruded sample containing the added sucrose had greater lipid stability than the other extruded samples. Lipid free-amino group content in all samples decreased with increased $A_w$ and temperature.

• Journal for History of Mathematics
• /
• v.22 no.3
• /
• pp.153-170
• /
• 2009

Zoltan, P. Dienes is a famous researcher and practitioner who has tried to teach mathematical structures to children for about 50 years. Even though his ideas of teaching mathematics and materials including MAB have been well known in Korea, they are only a part of his achievement he has developed for his whole life. So this article is designed for taking an overview of his whole life and achievement and getting some implications for today's mathematics education. In this article, his life story could be divided by five periods in terms of a scholastic career and his research achievement could be reorganized with respect to five theses: psychology of learning mathematics, mathematical curriculum, teacher education, games and material for mathematical learning. As a result, it is found that there is a deep connection between his personal life and his scholastic career.

• Applied Biological Chemistry
• /
• v.32 no.1
• /
• pp.1-7
• /
• 1989

The autoxidation products derived from methyl linolenate are isolated and characterized by using thin-layer chromatography, infrared, ultraviolet and nuclear magnetic resonance spectrometries. In addition, the propriety of the application of NMR spectrometry to the analysis of the autoxidation products is examined. Spectroscopic data indicate that the autoxidation of methyl linolenate produces hydroperoxides and trans, cis-substituted diene. The autoxidation products have a predominant cis, trans-conjugated diene system with some trans, trans-configuration. The spectroscopic data of ir, uv, and nmr are very consistent with each other, and further investigation of the multiplet region at $5.83{\sim}6.60ppm$ would be very helpful for the structural elucidation of the autoxidation products.

• Journal of Microbiology and Biotechnology
• /
• v.30 no.11
• /
• pp.1769-1776
• /
• 2020

As part of our current work to discover structurally and/or biologically novel compounds from Korean wild mushrooms, we isolated five ergostane-type steroids (1-5) from the fruiting bodies of Xerula furfuracea via repeated column chromatographic separations and HPLC purification. The chemical structures of the isolated steroids were shown to be (22E,24R)-24-methylcholesta-4,22-diene-3,6-dione (1), ergosta-7,22-diene-3β,5α,6β-triol (2), ergosta-7,22-diene-3β,5α,6β,9α-tetraol (3), (22E,24R)-5α,8α-epidioxyergosta-6,22-diene-3β-ol-3-O-β-D-glucopyranoside (4), and (22E,24R)-5α,8α-epidioxyergosta-6,9,22-triene-3β-ol-3-O-β-D-glucopyranoside (5)based on comparison of the data regarding their spectroscopic and physical properties with those of previous studies. Notably, this is the first report on the presence of the identified steroids (1-5) in this mushroom. We tested compounds 1-5 to determine their effects on adipogenesis and osteogenesis in the mouse mesenchymal stem cell line C3H10T1/2 and found that compounds 4 and 5 suppressed the differentiation of stem cells into adipocytes. Notably, in addition to its suppressive effect on adipogenesis, compound 5 was also shown to promote the osteogenic differentiation of stem cells. These findings demonstrate that the bioactive compounds isolated might be effective for the treatment of menopause-associated syndromes, such as osteoporosis and obesity, as the isolated compounds were shown to suppress adipogenesis and/or promote osteogenesis of stem cells.

• Journal of the Korean Chemical Society
• /
• v.34 no.5
• /
• pp.430-437
• /
• 1990

Various tris (${\eta}^4$-diene) molybdenums were easily synthesized by the reaction of various 1,3-dienes and molybdenum metal vapors by using metal atom reactor. The methyl substituent effect of the tris (${\eta}^4$-diene) molybdenum produced were discussed. And some alkadiene-molybdenum complexes which were easily decomposed in the air at room temperature were also formed.(C$_6$H$_{10}$)$_2$(CO)$_3$Mo were synthesized and its molybdenum-diene bond type were discussed.

• Analytical Science and Technology
• /
• v.7 no.3
• /
• pp.321-327
• /
• 1994

The mild thermal decomposition of 7, 7-dimethyl-1, 2, 3, 4, 5-pentaphenyl-7-silanorbornadiene with excess methyl alcohol proceeds to give 1-methoxydimethylsilyl-1, 2, 3, 4, 6-pentaphenylcyclohexa-2, 5-diene which is colorless needle crystal. The cophotolysis of the solution of 7-silanorbornadiene in the excess ethyl alcohol proceeds with loss of silylenes to give ethoxydimethylsilane which is insertion reaction product of silylene with O-H bond of ethyl alcohol. According to above results, it is presumed that the mechanism of photochemical decomposition and that of mild thermochemical decomposition of 7-silanorbornadiene are different.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2009.11a
• /
• pp.449-452
• /
• 2009

In order to improve incombustibility of EPDM(Ethylene propylene diene monomer)-based rubber, inorganic materials as $Al(OH)_3$ and $Sb_2O_3$ were added. The mechanical and thermal properties have been measured for vulcanized rubber loaded with different concentrations of $Al(OH)_3$ and $Sb_2O_3$. As inorganic material contents increases from 5phr to 30phr, the specific gravity and hardness increase while elongation at break decreases. This study performed incombustibility test and thermal analysis through TGA(Thermogravimetric Analyzer). As a results, incombustible and thermal properties of EPDM-based rubber were improved as $Al(OH)_3$ and $Sb_2O_3$ contents increase.

• Natural Product Sciences
• /
• v.17 no.2
• /
• pp.85-89
• /
• 2011

Bioassay-guided fractionation of the $CHCl_3$-soluble fraction of a MeOH extract of the fruiting bodies of Hygrophorus russula led to the isolation of five ergosterol derivatives (1 - 5). The structures of these compounds were identified as ergosterol peroxide (1), ergosta-4,6,8(14),22-tetraen-3-one (2), ergosta-7,22-diene-3${\beta}$,5${\alpha}$,6${\alpha}$-triol (3), ergosta-7,22-diene-3${\beta}$,5${\alpha}$,6${\beta}$,9${\alpha}$-tetraol (4), and 5${\alpha}$,6${\alpha}$-epoxy-ergosta-8(14),22-diene-3${\beta}$,7${\alpha}$-diol (5) by comparing their physicochemical and spectral data with those in the literature. These compounds were evaluated for in vitro cytotoxicity against A549 and XF498 cancer cell lines. Most of the tested compounds, except for compound 3, exhibited moderate cytotoxicity against both A549 and XF498 cell lines with $IC_{50}$ values ranging from 10.2 to 18.3 ${\mu}g/ml$ and from 11.4 to 24.6 ${\mu}g/ml$, respectively.

• Polymer(Korea)
• /
• v.25 no.2
• /
• pp.233-239
• /
• 2001

The ethylene propylene diene terpolymer (EPDM) blends with acrylonitrile butadiene rubber (NBR) were prepared by mechanical mixing method. Mooney viscosity, cure behaviors, compression set and dynamic mechanical properties were subsequently examined. Dynamic characteristics of the entire blends determined from a Rheovibron generally showed two glass transitions (T'$_{g}$s), -43$^{\circ}C$ and -4$^{\circ}C$ for NBR and EPDM, respectively. The tan $\delta$ peak monotonically shifted toward the higher temperature with increasing NBR content. It was also found that the optimum cure time was significantly decreased with loading of NBR.