• 생명과학회지
• /
• 제8권5호
• /
• pp.604-613
• /
• 1998

담배의 phytoalexin으로 알려진 capsidiol 생합성의 마지막 단계에 관여하는 5-epi-aristolochene hydroxy-lase 유전자의 일부를 RT-PCR 방법으로 클로닝하였다. 클로닝한 CYP-B3는 콩, 완두 등의 cytochrome P450계의 유전자와 높은 동일성을 보였으며 heme 결합부위로 알려진 FxxGxRxCxG을 포함하고 있는 것으로 나타났다. 또한 CYP-B3는 저온, 고온 또는 제초제 등에 의해서는 유도되지 않고 Elicitor에 의해서만 특이하게 유도되는 것으로 나타나 Phytoalexin 생합성에 관여하는 유전자임을 확인하였다. Cyt P450 억제제인 ancy-midol과 ketoconazol에 의해 CYP-B3의 전사는 억제되지 않는 반면 5-epi-aristolochene hydroxylase의 효소활성은 현저히 억제되는 것으로 나타나 이들 억제제는 전사후의 효소의 합성 또는 활성을 억제하는 것으로 나타났다.

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

• 공업화학
• /
• 제10권6호
• /
• pp.814-821
• /
• 1999

고비표면적의 활성탄소섬유(ACF: activated carbon fiber)를 분극성 전극으로 이용한 전기이중층 캐패시터(electric double layer capacitor)의 단위 cell test를 통하여, ACF의 비표면적, 세공의 크기 및 전기전도도가 캐패시터의 비축전용량에 커다란 영향을 미치고 있음을 확인할 수 있었고, 전해질은 $H^+$ 이온을 함유한 $H_2SO_4$이 가장 좋은 축전용량을 나타내었으나, 집전체 부식 등의 문제로 인하여, 실용화에 있어서는 우수한 충방전 거동을 나타낸 KOH계 전해질이 적당한 것으로 확인되었다. 분극성 전극으로 사용되는 ACF를 탄화 또는 후활성화 등이 후처리를 통하여 비축전용량을 급격히 증가시킬수 있었고, 3만회까지의 연속 충방전 실험에서 전기이중층 캐패시터는 2차전지에서는 찾아 볼 수 없는 매우 높은 충방전 효율과 긴 사용수명을 가지는 것을 확인할 수 있었다.

• 한국재료학회지
• /
• 제1권1호
• /
• pp.54-61
• /
• 1991

$YBa_2Cu_3O_{7-\delta}$ 단일 타게트를 사용하여 R. F. 마그네트론 스퍼터링법으로 MgO(100), Si(100)기판 위에 박막을 증착한 후, $880^{\circ}C$의 산소 분위기에서 1시간 동안 열처리를 하였다. 열처리 전 박막의 미세한 조성변화에 의해서도 열처리 후 박막의 미세구조 및 전기적 특성은 크게 변화했다. MgO(100)기판의 표면에 성장되는 입자들은 선택 배향적으로 성장하려는 경향을 가지므로 가늘고 길쭉한 입자 형상을 띠는 반면에 이들 입자위에 성장되는 다른 입자들은 결정 성장 방향의 선호도가 없으므로 둥근 모양의 입자형상을 가진다. 열처리 전 박학의 조성이 1-2-3을 벗어나면 증착 후 열처리할 때 액상이 형성되며, 액상의 양이 많을수록 선택 배향적 성장이 용이해져 texture를 쉽게 이룬다. 그러나 이러한 액상은 냉각 시에 초전도입자의 입계에 이차상으로 형성되기 때문에 초전도 박막의 전기적 특성, 특히 임계온도를 저하시킨다. 또한 $T_{c,\;zero}$는 $T_{c,\;on}$에 비해서 입계에 형성되는 이차상의 영향을 더 크게 받는다.

• 분석과학
• /
• 제6권2호
• /
• pp.217-223
• /
• 1993

저항가열식 진공중착기를 이용하여 실온(ambient temp.)과 $250^{\circ}C$에서 알루미나 기판 위에 Au/Cr, Au/Ni/Cr 및 Au/Pd/Cr 박막을 제조하였으며, 공기 중에서 $300^{\circ}C$, $450^{\circ}C$, $600^{\circ}C$의 온도로 각각 1시간 동안 열처리하였다. Au, Ni(또는 Pd) 및 Cr 박막의 두께는 각각 $1000{\AA}$, $300{\AA}$, 및 $50{\AA}$이었다. 박막 제조시 기판의 온도와 박막 제조 후 열처리 온도는 각 층의 상호확산으로 인하여 박막의 면저항값에 영향을 주었다. Auger depth profile 분석결과, Au/Cr 시스템에서는 기판의 온도는 $250^{\circ}C$로 하여 박막을 제조할 때 이미 Cr은 Au 표면으로 확산되었으며, 열처리 후에는 Au의 분포도만 변화하였다. Au/Ni/Cr과 Au/Pd/Cr 시스템의 경우 Ni와 Pd 모두 확산현상이 발견되었으며, 특히 Ni(약 45 at.%)는 Au 박막 표면으로 확산되어 산화되었다.

• 한국동물위생학회지
• /
• 제13권2호
• /
• pp.162-183
• /
• 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
• /
• 제34권6호
• /
• pp.1-10
• /
• 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
• /
• 제19권4호
• /
• pp.203-210
• /
• 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.

• 한국전기전자재료학회논문지
• /
• 제20권7호
• /
• pp.575-580
• /
• 2007

A 16 Mb 1T1C FeRAM device was integrated with BLT capacitors. But a lot of cells were failed randomly during the measuring the bit-line signal distribution of each cell. The reason was revealed that the grain size and orientation of the BLT thin film were severely non-uniform. And the grain size and orientation were severely affected by the process conditions of post heat treatment, especially nucleation step. The optimized annealing temperature at the nucleation step was $560^{\circ}C$. The microstructure of the BLT thin film was also varied by the annealing time at the step. The longer process time showed the finer grain size. Therefore, the uniformity of the grain size and orientation could be improved by changing the process conditions of the nucleation step. The FeRAM device without random bit-fail cell was successfully fabricated with the optimized BLT capacitor and the sensing margin in bit-line signal distribution of it was about 340 mV.

• Journal of Welding and Joining
• /
• 제31권6호
• /
• pp.50-57
• /
• 2013

Characterization of microstructures and cryogenic mechanical properties of electro beam (EB) welds between cast and forged Inconel 718 superalloys has been investigated. Optimal EBW condition was found in the beam current range of 36~39 mA with the constant travel speed of 12 mm/s and arc voltage of 120 kV for 10 mm-thick specimens. Electron beam current lower than 25 mA caused to occur the liquation microfissuring in cast-side heat affected zone (HAZ) of EB welds. The HAZ liquation microfissure was found on the liquated grain boundaries with resolidified ${\gamma}/Laves$ and ${\gamma}/NbC$ eutectic constituents. EBW produced welds showing a fine dendritic structure with relatively discrete Laves phase due to fast cooling rate. After post weld aging treatment, blocky Laves phase and formation of ${\gamma}^{\prime}+{\gamma}^{{\prime}{\prime}}$ strengtheners were observed. Presence of primary strengthener and coarse Laves particles in PWHT weld may cause to reduce micro-plastic zone ahead of a crack, leading to a significant decrease in Charpy impact toughness at $-196^{\circ}C$. Fracture initiation and propagation induced by Charpy impact testing were discussed in terms of the dislocation structures ahead of crack arisen from the fractured Laves phase.