• Journal of the Korean Chemical Society
• /
• v.36 no.6
• /
• pp.818-823
• /
• 1992

2-Ethylhexanoate compounds which contained Y, Er, Yb, Ba, and Cu were prepared separately. These metallo-organic compounds were dissolved together in the common solvent and the solution was homogeneous. From these solution, high $T_c$ superconductors $YBa_2Cu_3O_{7-\delta}(Y_{123})$, $ErBa_2Cu_3O_{7-\delta}(Er_{123})$, and $YbBa_2Cu_3O_{7-\delta}(Yb_{123})$ were prepared. XRD analysis showed that these superconductors were not single phase and contained some impurity phases including $YBa_2Cu_4O_8(Y_{124})$. This was also confirmed from the magnetic susceptibility measurement. Generally, critical temperatures were higher than that of the superconductors prepared by ceramic method. Volume diamagnetic susceptibility showed little variation compared to the specimen made by ceramic method.

• Korean Journal of Optics and Photonics
• /
• v.27 no.3
• /
• pp.95-100
• /
• 2016

High-power quasi-continuous-wave (qcw) operation in Yb-doped double-clad fiber lasers with near-diffraction-limited quality of the output beam is reported. Based on numerical simulation, we built a simple, all-fiberized Yb fiber laser, and a fiber-based master-oscillator power amplifier (MOPA). Both laser systems have successfully produced qcw output with average power greater than 150 W at 1080 nm and 10 ms pulse duration at 10 Hz repetition rate, corresponding to a peak power greater than 1.5 kW for 205 W of pump power at 976 nm. Laser performance, including beam quality and slope efficiency, was characterized in both configurations. Prospects for power scaling and applications are discussed.

• Microbiology and Biotechnology Letters
• /
• v.42 no.2
• /
• pp.99-105
• /
• 2014

A Bacillus strain capable of hydrolyzing locust bean gum was isolated as a producer of extracellular mannanase by way of an enrichment culture in an acidic medium from homemade soybean pastes. The isolate YB-1401 showed a biochemical identity of 61.1% with Brevibacillus laterosporus, while the nucleotide sequence of its 16S rDNA had the highest similarity with that of Bacillus amyloliquefaciens. The mannanase productivity of the Bacillus sp. YB-1401 was drastically increased by mannans. Particularly, maximum mannanase productivity was reached at approximately 265 U/ml in LB medium supplemented with konjac glucomannan (4.0%). The mannanase was the most active at $55^{\circ}C$ and pH 5.5. Mannanase activity was completely maintained after pre-incubation at pH 3.5 to 11.0 for 1 h. The predominant products resulting from the mannanase hydrolysis were mannobiose and mannotriose for LBG, guar gum or mannooligosaccharides. A small amount of mannose was also detected in the hydrolyzates.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.20 no.7
• /
• pp.581-586
• /
• 2007

[ $(Ba_{0.57}Sr_{0.33}Ca_{0.10})TiO_3$ ] (BSCT) powders, prepared by sol-gel method, were mixed with organic vehicle and the BSCT thick films were fabricated by the screen printing method. The structural and dielectric properties were investigated as a function of the $Yb_2O_3$ doping contents. As a result of the TG-DTA, exothermic peak was observed at around $670^{\circ}C$ due to the formation of the polycrystalline perovskite phase. All BSCT thick films showed the typical XRD patterns of a cubic polycrystalline structure. The average thickness of all BSCT thick films was about $70{\mu}m$. The grain size of the BSCT thick film doped with 0.7 mol% $Yb_2O_3$ was approximately $6.2{\mu}m$. The Curie temperature and relative dielectric constant at room temperature decreased with increasing $Yb_2O_3$ amount. Relative dielectric constant and dielectric loss of the specimen doped with 0.1 mol% $Yb_2O_3$ were 4637 and 19 % at Curie temperature, respectively.

• Microbiology and Biotechnology Letters
• /
• v.44 no.3
• /
• pp.370-375
• /
• 2016

Two xylanase genes were cloned into Escherichia coli from Bacillus sp. YB-1401 and B. amyloliquefaciens YB-1402, which had been isolated as mannanase producer from home-made doenjang, respectively, and their nucleotide sequences were determined. Both xylanase genes consisted of 642 nucleotides, encoding polypeptides of 213 amino acid residues. The deduced amino acid sequences of the YB-1401 and YB-1402 xylanase, designated Xyn1401 and Xyn1402, differed from each other by single amino acid residue, Asn for Xyn1401 and Lys for Xyn1402, corresponding to amino acid position of 127. Their amino acid sequences were highly homologous to those of xylanases belonging to the glycosyl hydrolase family 11. The 28 amino acid stretch in the N-terminus of both enzymes was predicted as signal peptide by SignalP4.1 server. Both xylanases were localized at the level of 91−94% in culture filtrate of the recombinant E. coli cells, suggesting they were secreted efficiently in E. coli cells. The optimal reaction conditions were 50℃ and pH 6.0 for Xyn1401, and 55℃ and pH 6.5 for Xyn1402, respectively, indicating one amino acid difference from each other affected pH and temperature profiles of their activities. In addition, their thermostabilities were somewhat different from each other.

• Journal of the Korean Ceramic Society
• /
• v.41 no.2
• /
• pp.170-175
• /
• 2004

The ferroelectric (Y $b_{x}$ $Y_{1-x}$)Mn $O_3$ thin films were fabricated by sol-gel method using Y-acetate, Yb-acetate, and Mn-acetate as raw materials. The stable (Y $b_{x}$ $Y_{1-x}$)Mn $O_3$ precursor solution (sol) was prepared through the reflux process with acetylaceton as a catalyst and coated on Si(100) substrate by spin coating. The heat treatment temperature and, Rw ($H_2O$/alkoxide moi ratio) dependence on crystallinity of thin films were studied. The lowest temperature for obtaining YbMn $O_3$phase and the optimum heat-treatment conditions were proved as at 7$50^{\circ}C$ and 80$0^{\circ}C$, respectively. The hexagonal YbMn $O_3$with c-axis preferred orientation could be obtained at Rw=1 condition. The remanent polarization for the thin films of x=0 or 1 was about 200 nC/㎤ while, for the specimens ot 0< x< 1, were 50∼100 nC/$\textrm{cm}^2$.

• 한국초전도학회:학술대회논문집
• /
• v.16
• /
• pp.71-71
• /
• 2006

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2001.05a
• /
• pp.28-28
• /
• 2001

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2001.05a
• /
• pp.104-104
• /
• 2001

• Proceedings of the Korean Ceranic Society Conference
• /
• 2003.04a
• /
• pp.143.2-143
• /
• 2003