• Progress in Superconductivity
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• 제13권2호
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• pp.127-132
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• 2011

Many research groups have been manufacturing coated conductor by various processes such as PLD, MOD, and MOCVD, but the methods with production cost suitable for wide and massive application of coated conductor did not develop yet. Spray pyrolysis method adopting ultrasonic atomization was tried as one of the possible option. GdBCO precursor films have been deposited on IBAD substrate by spray pyrolysis method at low temperature and converted to GdBCO by post heat treatment. Ultrasonic atomization was used to generate fine droplets from precursor solution of Gd, Ba, and Cu nitrate dissolved in water. Primary GdBCO films were deposited at $500^{\circ}C$ and oxygen partial pressure of 1 torr. After that, the films were converted at various temperatures and low oxygen partial pressures. C-Axis oriented films were obtained IBAD substrates at conversion temperature of around $870^{\circ}C$ and oxygen partial pressures of 500 mtorr ~ 1 torr in a vacuum. Thick c-axis epitaxial film with the thickness of 0.4 ~ 0.5 ${\mu}m$ was obtained on IBAD substrate. C-axis epitaxial GdBCO films were successfully prepared by ex-situ methods using nitrate precursors on IBAD metal substrate. Converted GdBCO films have very dense microstructures with good grain connectivity. EDS composition analysis of the film showed a number of Cu-rich phase in surface. The precursor solution having high copper concent with the composition of Gd : Ba : Cu = 1 : 2 : 4 showed the better grain connectivity and electrical conductivity.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• 제16권1호
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• pp.74-83
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• 2020

A number of so-called 'Type IV' cracking was reported to occur at the welded joints of the P91 steel or P92 steel reheat steam piping systems in Korean supercritical thermal power plants. The reheat steam piping systems are subjected to severe thermal and pressure loading conditions of coolant higher than 570℃ and 4MPa, respectively. In this study, piping analyses and design evaluations were conducted for the piping system of a specific thermal plant in Korea and suggestions were made how structural integrity could be improved so that type IV cracks at the welded joints could be prevented. Integrity evaluations were conducted as per ASME B31.1 code with implicit consideration of creep effects which was used in original design of the piping system and as per nuclear-grade RCC-MRx code with explicit consideration of creep effects. Comparisons were made between the evaluation results from the two design rules. Another approach with modification or reduction of the redundant supports in the piping systems was investigated as a tool to mitigate thermal stresses which should essentially contribute to prevention of Type IV cracking without major modification of the existing piping systems. In addition, a post weld heat treatment method and repair weld method which could improve integrity of the welded joint of P91 steel were investigated.

• Journal of Life Science
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• 제8권5호
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• pp.604-613
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• 1998

The last enzyme of the sesquiterpen phytoalexin capsidiol synthesis in tobacco cell, 5-epi-aristolochene hydro-xylase which convert 5-epi-aristolochene (EAS) to capsidiol, was cloned by a reverse transcription polymerase chain reaction strategy and cDNA library screening. Cloned CYP-B3 contained high probability amino acid matches to known plant cytochrome P450 sequences and open reading frame with the conserved FxxGxRxCxG heme-binding region. Transcripts of CYP-B3 were not detected in control cells, but induced in elicitor-treated cells. Furthermore, CYP-B3 transcripts were induced by fungal extracts and cellulase but not by other stimuli(chilling, heat shock and 2,4-D). Induction of CYP-B3 transcripts by elicitor treatment was not affected by ancymidol and ketoconazole treat-ments suggesting that an inhibition of hydroxylase activity by Cyt P450 inhibitors resulting from post translational processing event.

• The Plant Pathology Journal
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• 제21권3호
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• pp.262-269
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• 2005

An antiviral producing bacterial strain was isolated from a ginseng rhizosphere in Kangwon province of Republic of Korea. In order to identify the bacterial strain, microbiological, physiological and biochemical tests were performed, along with RAPD, 16S rRNA, 16S-23S rRNA ITS (intergenic spacer region) and DNA-DNA hybridization analyses. The bacterium was found to be a strain of Pseudomonas fluorescens, which was designated as Gpf01. The strain was grown in Muller-Hinton (MH) broth, and the culture supernatant obtained was filtered through a $0.45{\mu}l$ filter. It was further boiled at $100^{\circ}C$ and tested in two experiments for its ability to control a yellow strain of Cucumber mosaic virus (CMV-Y). In the first experiment, boiled culture filtrate (RCF) was treated on one half of the leaves of Chenopodium amaranticolor followed by CMV- Y inoculation on both halves. In the second experiment, BCF was treated on the lower leaves of Nicotiana tobacum var. Xanthi-nc, with the CMV-Y mechanically inoculated onto the upper untreated leaves. In the first experiment, BCF treatment was able to considerably reduce the number of viral lesion, and in the second experiment, plants treated with BCF showed no visible viral symptoms compared to the Muller-Hinton (MH) media treated controls 15 days post inoculation (dpi), and remained symptomless throughout the study period. Thus, Gpf01, identified as P. fluorescence, was able to produce an antiviral component in the culture filtrate, which was found to be heat stable, non-phytotoxic and effective in local as well as systemic hosts of CMV.

• Applied Chemistry for Engineering
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• 제10권6호
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• pp.814-821
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• 1999

The specific capacitance characteristics of the electric double layer capacitors(ELDC) which were made of phenol based activated carbon fiber(ACF) electrodes. Also the effect of aqueous electrolytes on the cell performance has been investigated with respect to different specific surface areas of electrodes and different kinds of aqueous electrolytes. It has been shown that larger surface area and pore size, higher conductivity of electrodes, and higher ion mobility of electrolytes have better specific capacitances. It has been found that heat treatment at $1200^{\circ}C$ and $CO_2$ post-activation at $900^{\circ}C$ of the electrode are effective to improve the specific capacitance over 145F/g and 165F/g, respectively. The EDLC showed high efficiency and long cycle life over 30000 cycles.

• Korean Journal of Materials Research
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• 제1권1호
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• pp.54-61
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• 1991

YBCO films deposited on MgO(100) and Si(100) by rf-magnetron sputtering using stoichiometric single target were annealed under oxygen atmosphere at $880^{\circ}C$ for 1 hr. The microstructure and superconducting properties of YBCO thin films depended on the composition of pre-annealed thin films. Basal planesuperconducting particles grown on MgO(100) substrate had small and rod-like shade due to preferred orientation, while superconducting film grown on the basal plane-superconducting particles showed round-shape particles. If pre-annealed thin film had nonstoichiometric composition, liquid phase was formed during the heat treatment, which made it easy for particles to grow in the preferred orientation and thus to form textured structure. But the thin films with the textured structure did not show good superconducting properties, especially $T_c$, since the liquid phase transformed into second phase in the grain boundary during the cooling. The effect of the second phase on $T_{c, \;zero}$ was greater than that on $T_{c, \;on}$.

• Analytical Science and Technology
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• 제6권2호
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• pp.217-223
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• 1993

Thin films of the Au/Cr, Au/Ni/Cr and Au/Pd/Cr systems were deposited on alumina substrates at ambient temperature and $250^{\circ}C$ in a high-vacuum resistance heating evaporator and annealed at $300^{\circ}C$, $450^{\circ}C$ and $600^{\circ}C$ for 1 hour in air, respectively. The film thicknesses of Au, Ni(or pd), and Cr were $1000{\AA}$, $300{\AA}$, and $50{\AA}$, respectively. The substrate temperature during deposition and the post-deposition annealing temperature affected the sheet resistance of thin-films due to the inter-diffusion of each layer. As a result of Auger depth profile analysis, in the Au/Cr system Cr already diffused out to Au surface during deposition at the substrate temperature of $250^{\circ}C$ and Au distribution changed after heat treatment. In the Au/Ni/Cr and Au/Pd/Cr systems, diffusion phenomena of Ni and Pd were found and especially Ni (approximately 45 at.%) diffused out to Au surface and oxidized.

• Korean Journal of Veterinary Service
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• 제13권2호
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• pp.162-183
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• 1990

From 1988 to 1989, 8 strains of canine parvovirus-2 (CPV-2) were isolated from the fecal specimens from the dogs that were clinically diagnosed as canine parvoviral enteritis in the veterinary hospitals located in the regions of Taejon and Chungbuk province. Studios on biological and physicochemical properties for the isolates were carried out. The results obtained by experiments are summarized as follows. 1. Among 62 fecal samples collected from the dogs with enteric diseases, 24 (38.7%) showed the haemagglutinating activity against porcine erythrocyte, ranging from 16 to 16, 384 of HA titers. 2. When 8 fecal specimens with high HA titer over 1, 000 were inocultated into CRFX cells, intranuclear inclusion bodies were obseverd in all of eight specimens, of w)lick three specimens showed cytoplasmic inclusions concurrently with the intranuclear inclusion bodies. 3. In study on species-specificity of haemagglutinating activity of the isolates, TJ-89-1 and TJ-89-2, it was found that the isolates revealed the highest haemagglutinating activity with porcine erythrocytes, showing the relatively lower haemagglutination titers with the erythrocytes from cat and rabbit. None of erythrocytes from other animals reacted with the isolates. 4. By the cross-haemagglutination inhibition test of the Isolates with reference viruses and sera, the Isolates were evidently identified as the strains of canine parvovirus-2. 5. In Physicochemical property test, it was evident that the isolates were stable in, lipid solvent, pH and heat treatment at $56^{\circ}C$ for 30 min. and contain DNA genome. 6. When seven puppies were inoculated intraorally with the isolate at HA titer of 8, 192, all of the puppies showed the symptoms of anorexia, vomiting, diarrhea and died at the 5th to 10th days post inoculation(pi). The fecal samples from all of the puppies revealed significantly high HA titers afterward the 5th days pi. Body temperature and the number of total leucocytes were slightly increased at the early stage of infection. but extremely decreased at the stage of collapse. HI titers of the sera started to increase at the 2nd to 3rd days pi reaching 512 to 1, 024 at the 4th to 5th day pi.

• Journal of Welding and Joining
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• 제34권6호
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• pp.1-10
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• 2016

Flux Cored Wire is the most widely used welding material for Flux Cored Arc Welding these days. This paper introduces the technical aspects of manufacturing FCW and the development trend of FCW for each type of steel and metal. The studies are ongoing to lower the production cost of seamless-type FCW since it has not been generally used in welding shops so far because of it high cost even though the seamless-type FCW has various advantages than folded-type FCW in terms of manufacturing technology. Meanwhile, a technical research has been carried out to develop a rutile type of FCW products which satisfies high toughness after post heat treatment. In addition, for high-speed fillet welding, there has been a development of welding materials which can be welded in Single Auto-Carriage 100 cpm or more and up to Twin Tandem 200 cpm without occurring any welding defect in order to improve the welding productivity. As Zn coated steel is being used recently to improve the corrosion resistance of the automotive parts, a research and development for Metal Cored Wire has been conducted to reduce the Si island produced in welding operation than those produced when using the former solid wires. A development of welding material that guarantees CTOD performance beyond $-40^{\circ}C$ CTOD to $-60^{\circ}C$ is underway by different steel grades, and FCW for super austenitic stainless steel is being developed as the corrosion resistant steel has been upgraded.

• Corrosion Science and Technology
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• 제19권4호
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• pp.203-210
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• 2020

The corrosion behavior of super austenitic stainless steel was studied by examining the characteristics of the sigma phase formed in the steel. A range of experimental and analytical methods was employed, including potentiodynamic polarization tests, critical pitting temperature tests, transmission electron microscopy, and energy-dispersive spectroscopy. Three steel samples with different sigma phase levels were obtained by intentionally adjusting the manufacturing process. The results showed that the corrosion resistance of the samples was strongly dependent upon the size and distribution of the sigma phase precipitated in the samples. The larger the size of the sigma phase, the higher the Mo content in the sigma phase and the higher the depletion level of Mo at the interface between the matrix/sigma phase, the more samples with a coarse-sized sigma phase were susceptible to localized pitting corrosion at the interface. These results suggest that various manufacturing processes, such as welding and the post-heat treatment of the steel, should be optimized so that both the size and fraction of the sigma phase precipitated in the steel are small to improve the resistance to localized corrosion.