• Research in Plant Disease
• /
• v.12 no.3
• /
• pp.168-177
• /
• 2006

Thirty-nine strains of Colletotrichum gloeosporioides and 5 strains of C. acutatum stored in Korean Agricultural Culture Collection(KACC) were re-identified based on molecular characteristics of ribosomal internal transcribed spacer(ITS) and partial $\beta$-tubulin gene and cultural characteristics on potato dextrose agar(PDA) and Benomyl-added PDA. As the results, 19 strains were identified as C. acutatum with 13 strains of group A2, 5 strains of group A3, and 1 strain of group A4. In addition, 20 strains were identified as C. gloeosporioides with 18 strains of ribosomal DNA group(RG) 4 and 2 strains of RG6. The rest were identified as C. boninense RG5(2 strains), C. coccodes RG2(2 strains), and C. dematium RG12(1 strain). Out of domestic 31 strains, 12 strains were identified as C. acutatum A2, one strain as C. acutatum A3, 14 strains as C. gloeosporioides RG4, 2 strains as C. gloeosporioides RG6, one strains as C. boninense RG5 and one strain as C. dematium RG12. We also discussed taxonomy of C. gloeosporioides and C. acutatum and composition of C. gloeosporioides/C. acutatum isolates from major crops in Korea.

• Journal of the Chungcheong Mathematical Society
• /
• v.23 no.2
• /
• pp.231-236
• /
• 2010

Using the properties of the concave function, we show that the Hausdorff dimension of the product $C_{\frac{a+b}{2},\frac{a+b}{2}}{\times}C_{\frac{a+b}{2},\frac{a+b}{2}}$ of the same symmetric Cantor sets is greater than that of the product $C_{a,b}{\times}C_{a,b}$ of the same anti-symmetric Cantor sets. Further, for $1/e^2$ < a, b < 1/2, we also show that the dimension of the product $C_{a,a}{\times}C_{b,b}$ of the different symmetric Cantor sets is greater than that of the product $C_{\frac{a+b}{2},\frac{a+b}{2}}{\times}C_{\frac{a+b}{2},\frac{a+b}{2}}$ of the same symmetric Cantor sets using the concavity. Finally we give a concrete example showing that the latter argument does not hold for all 0 < a, b < 1/2.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.859-860
• /
• 2006

TiC-$TiB_2$-SiC system was a ternary eutectic, whose eutectic composition was 34TiC-$22TiB_2$-44SiC (mol%). TiC-$TiB_2$-SiC ternary eutectic composite were synthesized by a floating zone method using TiC, $TiB_2$ and SiC powders as starting materials. The TiC-$TiB_2$-SiC eutectic composite showed a lamellar texture. TiC(022), $TiB_2(010)$ and SiC(111) of the eutectic composite were perpendicular to the growth direction. TiC-$TiB_2$-SiC ternary eutectic composite had specific relationship among the crystal planes: TiC[011]//$TiB_2[010]$//SiC[112], TiC(200)//$TiB_2$(001)//SiC(402) and $TiC(1\bar{1}1)$//$TiB_2(101)$//SiC(220).

• Korean Journal of Materials Research
• /
• v.5 no.7
• /
• pp.880-887
• /
• 1995

Melt spun YB $a_2$C $u_3$A $g_{15}$ and YbB $a_2$C $u_3$A $g_{x}$(x=5, 16 and 53) precursor alloy ribbons were oxidized at 263~322$^{\circ}C$, and heat-treated at 872~89$0^{\circ}C$ under 1.0atm oxygen pressure. In addition, about ten ribbons were stacked and coupled by pressing, and then followed the same heat treatment. YB $a_2$C $u_3$ $O_{7-{\delta}}$(1-2-3) or YbB $a_2$C $u_3$ $O_{7-{\delta}}$(1-2-3) phase was formed in both the ribbons and the multilayered specimens. The formed 1-2-3 phases were not texturized in all the ribbons, but slightly texturized in the multilayered specimens. $J_{c}$ was not achieved in all the ribbons at 77K and zero magnetic field. Among the multilayered specimens, YB $a_2$C $u_3$A $g_{15}$ and YbB $a_2$C $u_3$A $g_{16}$ showed $J_{c}$ of 260 and 180A/$\textrm{cm}^2$, respectively. YB $a_2$C $u_3$A $g_{15}$ and YbB $a_2$C $u_3$A $g_{16}$ are considered to be the appropriate compositions in producing textured superconducting oxides with improved $J_{c}$ by pressing. Onset critical temperature ( $T_{on}$ ) of the multilayered YB $a_2$C $u_3$A $g_{15}$ was 92K while those of YbB $a_2$C $u_3$A $g_{x}$(x=5 , 16 and 53) were 88~90K. , 16 and 53) were 88~90K.

• Journal of the Korean Applied Science and Technology
• /
• v.14 no.1
• /
• pp.61-76
• /
• 1997

Triacylglycerols of the seeds of Ginkgo biloba have been resolved by high-performace liquid chromatography(HPLC} in the silver-ion and reverse-phase modes. The fatty acids were identified by a combination of capillary gas chromatography and gas-chromatography /mass spectrometry as the methyl and /or picolinyl ester. The main components are $C_{18:2{\omega}6}$(39.0mol%), $C_{18:1{\omega}7}$(asclepic acid 21.5mol%), and $C_{18:1{\omega}9}$(oleic acid, 13.8mol%). Considerable amounts of unusual acid such as $C_{20:3{\Delta}^{5,11,14}$ (5.7mol%), $C_{18:2{\Delta}^{5,9}$(2.8mol%), and $C_{18:3}{\Delta}^{5,9,12}$(1.6mol%), were checked. In addition, an anteiso-branched fatty acid, 14-methylhexadecanoic acid, was also present as a minor component(0.9 mol%). The triacylglycerols were separated into 17 fractions by reverse-phase HPLC, and the fractionation was achieved according to the partition numnber(PN) in which a ${\Delta}^5$-non methylene interrupted double bond($^5$-NMDB) showed different behaviour from a methylene interrupted double bond in a molecule with a given cahinlength. Silver-ion HPLC exhibited excellent resolution in which fractions(23 fractions) were resolved on the basis of the number and configuration of double bonds. In this instance, the strength of interaction of a ${\Delta}^5$-NMDB system with silver ions seemed to be weaker than a methylene interrupted double bond system. The principal triacylglycerol species are as follows ; $(C_{18:2{\omega}6)2}/C_{18:1{\omega}7}$, $C_{18:1{\omega}9}/C_{18:1{\omega}7}/C_{18:2{\omega}6}$, $(C_{18:1{\omega}7)2}/C_{18:2{\omega}6}$, $C_{16:1{\omega}7}/C_{18:1{\omega}9}/C_{20:3}{\Delta}^{5,11,14}$, $C_{16:1{\omega}7}/C_{18:1{\omega}7}/C_{20:3}{\Delta}^{5,11,14}$, $C_{18:1{\omega}9}/C_{18:1{\omega}7}/C_{18:2{\omega}6}$, $C_{18:1{\omega}9}/C_{18:2}{\Delta}^{5,5}/C_{20:3}{\Delta}^{5,11,14}$, $(C_{18:1{\omega}7)2}/C_{18:2{\omega}6}$ and $(C_{18:1{\omega}9)2}/C_{18:2{\omega}6}$, while simple triacylglycerols without $C_{18:2{\omega}6})_3$ were not present. Stereospecific analysis showed that fatty acids with ${\Delta}^5$-NMDB system and saturated chains were predominantly located at the site of sn-3 carbon of glycerol backbones. It is evident that there is asymmetry in the distribution of fatty acids in the TG molecules of Ginkgo nut oils.

• Journal of the Korean Ceramic Society
• /
• v.40 no.1
• /
• pp.18-23
• /
• 2003

Composite powder of$B_4C-A1_2O_3$was prepared from a mixed powder of$B_2O_3/A1/C$by SHS under argon pressure instead of using a chemical furnace. A mixture of$B_2O_3,$Al and C powder (equivalent amounts to the reaction,$2B_2O_3+4A1+C=B_4C+2A1_2O_3)$was ball milled for 2 h. The mixed powder was placed in a SHS reactor and filled with 10 atm of argon gas and ignited. The inner and outer products were the same by XRD analysis. It was consisted of a composite powder of$B_4C-A1_2O_3$without $AlB_{12}/C_2$which was always produced using a chemical furnace. The composite powder was about$60~100{mu}m$size which was composed of crystalline particles of about 0.3~l${mu}m$size. But when 15 atm of argon was employed, partial sintering took place to give rise hard composite powder of$15~25{mu}m$$B_4C$with $0.1~0.2{mu}m$$A1_2O_3.$

• Journal of the Korean Chemical Society
• /
• v.34 no.6
• /
• pp.517-526
• /
• 1990

The crystal structures of two alditol acetates, D-glucitol hexaacetate and xylitol pentaacetate, have been determined by diffraction methods with Mo-K$\alpha$radiation, using direct methods for phase determinations. The crystal data are: for D-glucitol hexaacetate, P2$_1$, with a = 10.275 (2), b = 8.363 (1), c = 12.560 (5) $\AA;\beta$ = 95.97 $(2)^{\circ}$, Z = 2; for xylitol pentaacetate, P2$_1$/C with a = 18.126 (1), b = 11.422 (2), c = 8.649 (1) $\AA$, $\beta = 95.03 (1)^{\circ}$, Z = 4. Both molecules have extended zigzag carbon chain conformations which differ from previous studies of the structures of D-glucitol and xylitol and also differ from NMR studies on alditol acetates. The bond lengths and angles are normal, with mean values over both structures of C($sp^3)-C(sp^3): 1.514 (10),\; C(sp^3)-O: 1.444 (6),\; C(sp^2)-O: 1.347 (9),\; C(sp^2)=O: 1.197 (6),\; C(sp^2)-C(sp^3): 1.479(9){\AA},\; C(sp^3)-C(sp^3)-C(sp^3): 114.6 (17),\; O-C(sp^3)-C(sp^3): 109.4 (23),\; C(sp^2)-O-C(sp^3): 117.4 (6),\; O=C(sp^2)-O: 122.6 (6),\; C(sp^3)-C(sp^2)-O: 111.8 (7),\; C(sp^3)-C(sp^2)=O: 125.5 (4)^{\circ}$. The atoms of acetate groups are in coplanar. There are no particularly short intermolecular contacts and the molecules are held together by van der Waals force only.

• Publications of The Korean Astronomical Society
• /
• v.14 no.1
• /
• pp.33-37
• /
• 1999

We have constructed a synthetic spectrum of the 2.5 micron $C_2H$ bands and compared them with diminutive structures in the near-infrared spectra of Comets P/Halley and West (1976 VI). We found that the Q branches of the $C_2H$ bands coincide with two small emission peaks in the spectra of the comets. We undertook Monte Carlo simulations using observed emission intensities of $C_2$ and possibly $C_2H$ in Comet P/Halley in order to derive a lifetime range of $C_2H$ and a production rate at the time of observations of P/Halley. We obtained a $C_2H$ production rate of $1\times10^{27}\;sec^{-1}$ for P/Halley on December 20, 1985, assuming the 2.5 micron features are due to $C_2H$. We derived a very short lifetime (<100 seconds) of $C_2H$ at 1AU heliocentric distance, assuming that the only parent molecule for $C_2H$ and $C_2$ is $C_2H$. Using this short lifetime we were unable to fit our $C_2$ distribution model to $C_2$ distribution curves observed by O'Dell et al.(1988), because our curve shows a steep slope compared with the observed one. We conclude that there must be significant additional source(s) for $C_2H$ and $C_2$ other than $C_2H_2$.

• The Korean Journal of Zoology
• /
• v.34 no.2
• /
• pp.228-231
• /
• 1991

The phenotyping of the sixth complement component (C6) was performed on plasma or serum samples from 383 unrelated Korean, by IEF and immunoblotting using anti-human C6 serum. Three common allotypes, C6 A, C6 B and C6 B2 and two rare allotypes, C6 Ml and C6 Mu were observed. The allele frequencies of C6*A, C6*B and C6*B2 were estimated to be 0.4399, 0.5144, 0.0392, respectively. These frequencies are similar to those of the Eastasian populations.

• YAKHAK HOEJI
• /
• v.48 no.2
• /
• pp.135-140
• /
• 2004

For the development of new COX-2 inhibitors, 1,5-diarylhydantoins 5a∼5c and 1,5-diaryl-2-thiohydantoin 6a∼6c were synthesized from commercially available phenylacetic acids through esterification, bromination, C-N bond formation and cyclization. Esters 2a∼c were efficiently synthesized from the starting materials 1a∼c by refluxing in absolute methanol for 3 hours with catalytic concentrated sulfuric acid. Bromination of 2a∼c was carried out with use of N-bomosuccinimide at rt in dichloromethane. The bromine of 3a∼c was substituted with aniline in ethanol or N,N-dimethylformamide to provide 4a∼c. Hydantoins and 2-thiohydantoins were synthesized from 4a∼c by treatment of potassium isocyanate or potassium thiocyanate in dil-ethanol with triethylamine.