• Journal of Information Display
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• v.9 no.2
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• pp.5-8
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• 2008

Bottom gate thin film transistors (TFTs) with microcrystalline and amorphous Si (a-Si) double active layers (DAL) were fabricated. Since the process of DAL TFTs can use that of conventional a-Si TFTs, these DAL TFT process has advantages, such as low cost, large substrate, and mass production capacity. In order to analyze the degradation characteristics in saturation region for driving TFTs of active matrix organic light emitting diode, three different dynamic stresses were applied to DAL TFTs and a-Si TFTs. The threshold voltage shift of DAL TFTs and a-Si TFTs during 10,000 second stress is 0.3V and 2V, respectively. DAL TFTs were more reliable than a-Si TFTs.

• Journal of Industrial Technology
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• v.30 no.B
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• pp.69-74
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• 2010

Chitinolytic activity was enhanced by coexpression of endo-chitinase gene (chiA) and chitobiosidase gene (chiB) from Serratia marcescens KFRI314 using constitutive expression vector, pHCEIA, in E. coli. Coexpression vector was constructed by inserting ribosome binding site (RBS) into junction between two chitinase genes. SDS-PAGE analyses showed that two chitinase were constitutively expressed while E. coli clones expressing two chitinases simultaneously increased halo size on colloidal chitin plate. Furthermore, the chitinolytic activities were much enhanced in coexpressed clones when degradation patterns of substrate analogues such as 4-MU-(NAG), $4-MU-(NAG)_2$,$4-MU-(NAG)_3$ were used. Consequently, the combined use of endochitinase and chitobiosidase greatly increased overall chitinolytic activities on recombinant E. coli clones.

• Journal of Industrial Technology
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• v.30 no.B
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• pp.61-68
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• 2010

Three chitinase genes (chiA, chiB, and chiC) were cloned into E. coli by PCR amplification from Serratia marcescens KFRI314. The sizes of cloned chitinase genes were 1692 bp, 1500 bp, and 1443 bp which correspond to 563, 499, and 480 amino acids, respectively. Recombinant chitinases were overexpressed using pHCEIA expression vector and purified to homogenity. The molecular weights of chitinases were about 60kDa, 50 kDa, 52 kDa, respectively. Optimum pHs were around pH 5~6 and optimum temperatures were $45{\sim}50^{\circ}C$ while 90% of enzyme activities were stable up to $50^{\circ}C$. The specific activities of ChiA, ChiB, and ChiC were 233.1, 278.8, $111.3{\mu}mol\;(min)^{-1}\;mg^{-1}$ against colloidal chitin. From experiments using TLC and fluorescent substrate analogues, it was demonstrated that ChiA was endo-chitinase while ChiB and ChiC were chitobiosidase.

• Korean Journal of Microbiology
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• v.38 no.4
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• pp.245-245
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• 2002

Catabolic pathways for the degradation of various aromatics by Sphingomonas yanoikuyae Bl are intertwined, joining at the level of substituted benzoates, which are further degraded vita ring cleavage reactions. The mutant strain EK497, which was constructed by deleting a large DNA region containing most of the genes for biphenyl, naphthalene, m-xylene, and m-toluate degradation, was unable to grow on all of the aromatics tested except for benzoate as the sole source of carbon and energy.S. yanoikuyae EK497 was found to possess only catechol ortho-ring cleavage activity due to deletion of the genes for the meta-cleavage pathway. Wild-type S. yanoikuyae Bl grown on benzoate has both catechol orthoand meta-cleavage activity. However, m-xylene and m-toluate, which are metabolized through methylbenzoate, and biphenyl, which is metabolized through benzoate, induce only the meta-cleavage pathway, suggesting the presence of a substrate-dependent induction mechanism.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.9
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• pp.736-742
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• 1991

N$^{+}$poly gate NMOSFETs and p$^{+}$ poly gate (surface type) PMOSFETs with three different gate oxides(SiO2, NO, and ONO) were fabricated. The rapid thermal nitridation and reoxidation techniques have been applied to gate oxide formation. The current drivability of the ONO NMOSFET shows larger values than that of the SiO2 NMOSFET. The snap-back occurs at a lower drain voltage for SiO$_2$ cases for ONO NMOSFET. Under the maximum substrate current bias conditions, hot-carrier effects inducting threshold voltage shift and transconductance degradation were investigated. The results indicate that ONO films exhibit less degradation in terms of threshold voltage shift. It was confirmed that the ONO samples achieve good improvement of hot-carrier immunity. In a SiO$_2$ SC-PMOSFET, with significant boron penetration, it becomes a depletion type (normally-on). But ONO films show excellent impurity barrier properties to boron penetration from the gate.

• Journal of Ocean Engineering and Technology
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• v.18 no.1
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• pp.75-79
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• 2004

Organic coatings are widely used to control of the corrosion of a steel structure. The water in coatings may cause the coatings to swell, leading to the degradation of the coatings. In addition, water affects the permeation of oxygen and other corrosive agents, and consequently, the presence of such substances at coating-metal interface promotes corrosion of the metal substrate. In this study, the anticorrosive properties of 4 types of coating, such as epoxy-epoxy, epoxy-urethane, urethane-epoxy, urethane-urethane, were evaluated. The evaluation tests were conducted under cyclic water-absorption/desorption conditions, consisting of alternative exposure to diluted 0.001M-LiCl(a$H_2O$≒1) and concentrated 10M-LiCl(a$H_2O$≒0.15). The anticorrosive performance of coatings was found to decrease in the order of urethane-urethane > urethane-epoxy > epoxy-epoxy coating.

• Journal of the Korean Ceramic Society
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• v.37 no.3
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• pp.288-293
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• 2000

Effects of contact damage and residual stress for two kinds of dental restorative layered ceramics, porcelain/alumina and porcelain/zirconia bilayers, were observed with Hertzian and Vickers indentation methods. Indentation stress-strain behavior of each material, strength degradation of the coating material, and crack propagation behavior in the coating layer after Vickers indentation were examined by an optical microscope. As a result, porcelain as coating materials showed the classical brittleness. It was inferred that damage and strength in two bilayer system were dependent on thermal expansion mismatch between the coating material and the substrate, which affected the strength degradation. Residual stress resulting from thermal expansion mismtch was formed in the coating layer, and specially in the case of porcelain/zirconia, residual stress was eliminated as coating thickness decreased.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.262-268
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• 2003

Organic coatings are widely used to control the corrosion of steel structure. The water in coatings may cause swelling or solvation of coatings, leading to the degradation of coatings. In addition, water affects the permeation of oxygen and other corrosive agents, and consequently the presence of such substances at coating-metal interface promotes corrosion of metal substrate. In this study, the anticorrosive properties of 4 types of coating, such as epoxy-epoxy, epoxy-urethane, urethane-epoxy, urethane-urethane, were evaluated. The evaluation tests were carried out under cyclic water-absorption/desorption conditions, consisting of alternative exposure to diluted 0.001M-LiCl($a_{1120}{\fallingdotseq}1$) and concentrated l0M-LiCl($a_{1120}{\fallingdotseq}0.05$). The anticorrosive performances of coatings were found to decrease in the order of urethane-urethane> urethane-epoxy> epoxy-epoxy coating.

• Journal of the Korean institute of surface engineering
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• v.39 no.4
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• pp.147-152
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• 2006

Failure mechanisms of electron beam physical vapor deposited thermal barrier coatings(EB-PVD TBCs) that occur during thermal cyclic oxidation were investigated. The investigations include microstructural degradation of NiCrAIY bond coat, thermally grown oxides(TGOs) along the ceramic top coat-substrate interface and fracture path within TBCs. The microstructural degradation of the bond coat during cyclic oxidation created Al depleted zones, resulting in reduction of NiAl and ${\gamma}$-Ni solid solution phase. It was observed that the fracture took placed primarily within the TGOs or at the interfaces between TGOs and bond coat.

• Korean Journal of Materials Research
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• v.7 no.3
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• pp.203-212
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• 1997

This paper evaluated the feasibility of laser consolidation for improving the properties of the plasma coated layer, Further, the mechanim of the degradation sequence of the chrome carbide layer applied on the turbine blades was postualted. The laser consolidation could be successfully applied for improcing the surface properties of the plasma coated blade, if a proper condition was carefully chosen. The consolidated layer had erosion & corrosion resistance and vond strength superiro to those of the as-plasma coated layer. The properties of the consolidated layer were strongly dependent upon the degree of dilution, especially on the Fe pickup from the substrate. The degradation of the plasma coating layer was thought to be a reault of the repeating action of the solid particle erosion, corrosion penetration through the pores and oxide films formed along the interlayer surface and impact spalling.