• Progress in Superconductivity and Cryogenics
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• v.8 no.1
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• pp.23-25
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• 2006

Optimization of process variables, including oxygen and water partial pressure and also an nesting temperature, was performed in batch-type process to fabricate YBCO films on LaAlO3 single crystal. In this work, YBCO oxide powder was used as a starting precursor for metal-organic deposition(MOD)method. The precursor films were fabricated in batch furnace and they were converted to the epitaxial YBCO films at the same furnace with varying the process variables. The oxygen partial pressure was varied from 100ppm to 2000ppm and the water partial pressure from 1.2% to 12.2%. The window for optimal P(O2) was narrow about 700ppm for batch-type process. YBCO films in bathc-thype MOD process were optimized at 740-770oC and P(H2O) of 2.3%-7.3%.

• Journal of Microbiology and Biotechnology
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• v.29 no.3
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• pp.392-400
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• 2019

Chondroitin, the precursor of chondroitin sulfate, which is an important polysaccharide, has drawn significant attention due to its applications in many fields. In the present study, a heterologous biosynthesis pathway of chondroitin was designed in a GRAS (generally recognized as safe) strain C. glutamicum. CgkfoC and CgkfoA genes with host codon preference were synthesized and driven by promoter Ptac, which was confirmed as a strong promoter via GFPuv reporter assessment. In a lactate dehydrogenase (ldh) deficient host, intracellular chondroitin titer increased from 0.25 to 0.88 g/l compared with that in a wild-type host. Moreover, precursor enhancement via overexpressing precursor synthesizing gene ugdA further improved chondroitin titers to 1.09 g/l. Chondroitin production reached 1.91 g/l with the engineered strain C. glutamicum ${\Delta}L-CgCAU$ in a 5-L fed-batch fermentation with a single distribution $M_w$ of 186 kDa. This work provides an alternative, safe and novel means of producing chondroitin for industrial applications.

• The Korean Journal of Zoology
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• v.39 no.2
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• pp.215-222
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• 1996

In the previous studies, we have demonstrated that prorenin converting enzyme (PRECE) was identical to the epidermal grouch factor-binding protein (EGF-BP) type B, which was a member of the mouse glandular kallikrein family, To examine whether or not EGF-BP type A and C are involved in the processing of prorenin, we have cloned the CDNAS of the EGF-BP type h and C from a library of male ICR mouse submandibular gland (SMGI. And then CHO cells were transfected with the EGF-BP expression plasmids. and stable cell lines expressing a high level of the EGF-BPS precursor were obtained. The conditioned medium was then treated with trypsin, which has been knotvn to effectively convert the EGF-BP type A and C precursor to the active forms. 수ubsequentlv, the prorenin converting activity of the trypsin-treated or untreated medium was examined. PRECE converted exactly prorenin to renin, but the prorenin converting activities of EGF-BP type A and C were not detected. From these results, it seems that only type B of these EGF-BPs is involved in processing Ren 2 prorenin in mouse SMG.

• Journal of the Korean Ceramic Society
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• v.38 no.8
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• pp.761-764
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• 2001

새로운 AlN 박막 제조용 단일 전구체로 AlCl$_3$: $^{t}$ BuNH$_2$을 합성하였다. c축으로 배향된 AlN 박막을 80$0^{\circ}C$에서 사파이어(0006) 단결정 위에 MOCVD 공정으로 증착시켰다. 본 전구체를 사용함으로 박막내의 잔류탄소 및 산소의 오염을 크게 낮출수 있었으며 Al:N의 비율이 1:1인 화학량론비의 AlN 박막을 제조할 수 있었다. 단일 전구체의 결정 구조는 단결정 X선 구조분석과 원소분석을 통하여 규명하였으며 박막분석은 SEM, XRD, SEM, AFM과 RBS 등으로 행하였다.

• Journal of the Korean Ceramic Society
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• v.34 no.12
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• pp.1247-1253
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• 1997

Sinter-active yttria powders were prepared by a solution precipitation with using a self-decomposing precipitation agent NH2CONH2(urea). The cold-pressed powders can be sintered to full density and the microstructure of grains less than 200 nm at a temperature as low as 120$0^{\circ}C$. The activity of the yttria powder has been controlled by varying nucleation conditions during precipitation and by minimizing formation of aggregates. The type of precursor is decisive in preparation of a sinter-active oxide powder, and urea is desirable as a precipitation agent for an active yttrium oxide powder.

• Korean Journal of Materials Research
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• v.17 no.1
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• pp.1-5
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• 2007

GaN thin fan were grown by spin coated colloidal GaOOH precursor. Polycrystalline GaNs with crystalline size of $10{\sim}100nm$ were grown on $SiO_2$ substrate. The shape of crystallite above $900^{\circ}C$ had the hexagonal plate and column type. X-ray diffraction patterns for them correspond to those of the hexagonal wurtzite GaN. With increasing droplets. i.e, thickness of deposited layers, XRD intensity increased. PL (photoluminescence) spectrum consisted with an weak near band-edge emission at 3.45 eV and a broad donor-acceptor emission band at 3.32 eV. From the low temperature PL measurement on GaN grown at $800^{\circ}C$ that the shallow donor-acceptor recombination induced emission was more intense than the near band-edge excitonic emission.

• 한국초전도학회:학술대회논문집
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• v.15
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• pp.65-65
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• 2005

• Korean Journal of Materials Research
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• v.13 no.3
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• pp.180-184
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• 2003

Ce-doped $Y_2$SiO$_{5}$ phosphor particles of spherical morphology, fine size, high crystallinity and high photoluminescence (PL) intensity were prepared by spray pyrolysis. When nitrate precursor solution is adopted, hollow particles were formed by uneven drying rate between surface and inside of droplet. Citric acid and ethylene glycol were introduced as polymeric precursor to control the morphology of particles. When polymeric solution is adopted, polymeric chain is formed by the esterification reaction between carboxyl and hydroxy groups of citric acid and ethylene glycol, and considered as controlling the drying characteristics of droplet. $Y_2$$SiO_{5}$ :Ce phosphor particles prepared from polymeric precursor solution were spherical, filled, fine size and not agglomerate before and after post heat treatment. The optimum doping concentration of cerium was 0.5 mol% of overall solution concentration. The optimum amount of TBOS of high PL intensity and pure crystallinity of X2-type $Y_2$$SiO _{5}$ was 105% of stoichiometric amount. The PL intensity of $Y_2$X$/_{5}$ :Ce phosphor particles prepared using the polymeric precursor solution was 164% of that of the nitrate precursor solution due to homogeneous composition and good morphology.y.

• Journal of the Korean Ceramic Society
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• v.52 no.4
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• pp.243-247
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• 2015

Si(Al)ON precursor was synthesized by formation of new Si-N bond using organoaluminum imine and liquid type poly(phenyl carbosilane). It was decomposed between $200-600^{\circ}C$, and the ceramic yield was 51% after pyrolysis. 150 - 200 nm in thickness of coating film was obtained by spin coating method. The precursor was easily oxidized during process because it was unstable in air. However the oxygen content was limited to 0.5 - 0.7 to silicon in heat treatment step. Even though the content of nitrogen was decreased by pyrolysis, Al-N and Si-N bonds were formed in ammonia atmosphere, and Si(Al)ON film was formed with 0.2 in content to silicon.

• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2751-2755
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• 2011

The visible vibronic emission spectrum was recorded from the corona discharge of precursor 1,2,3,4-tetramethylbenzene with a large amount of inert carrier gas helium using a pinhole-type glass nozzle coupled with corona excited supersonic expansion. The spectrum showed a series of vibronic bands in the $D_1{\rightarrow}D_0$ electronic transition of jet-cooled benzyl-type radicals formed from the precursor in a corona excitation. The analysis confirmed that two isomeric radicals, 2,3,4- and 2,3,6-trimethylbenzyl radicals, were produced as a result of removal of a hydrogen atom from the methyl group at different substitution positions. For each isomeric product, the electronic transition and a few vibrational mode frequencies were determined in the ground electronic state.