• Fisheries and Aquatic Sciences
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• 제14권2호
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• pp.73-78
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• 2011

Vibrio parahaemolyticus possesses two flagella systems: polar and lateral flagella for swimming in liquid and swarming on solid surfaces or in viscous environments. To elucidate the pathogenic role of these dual flagella systems, we constructed single- and double-deletion mutants of the lafA and flhAB flagellum genes and investigated their biofilm formation, cell adhesion, and colonization of the small intestine of suckling mice. The double-mutant strain was more impaired in biofilm formation than either of the single-mutant strains. In addition, the lafA, flhAB, and double-mutant strains showed 40%, 45%, and 60%, respectively, lower adherence to HeLa cells than the wild-type strain. Moreover, the lafA, flhAB, and double-mutant strains exhibited 49%, 5.6 and 6.7 times, respectively, lower colonization in a competition assay than the wild-type strain. These findings indicated that polar flagella were more important than lateral flagella for the pathogenesis of V. parahaemolyticus.

• 한국작물학회지
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• 제41권6호
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• pp.718-724
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• 1996

본 실험에서는 콩 재배품종과는 친화성이 없다고 알려진 R. fredii (fast-grower)와 기존의 근류균계인 B. japonicum 간의 상호작용 및 숙주친화성 등을 효율적으로 확인하기 위하여 뿌리분할방법(split-root system)을 사용하였으며, 근류균 이용을 위한 기초 자료를 얻을 목적으로 실험이 수행되었다. Lee와 Peking 품종 및 R. fredii인 PRC205(P205) 균계와 B. japonicum인 USDA110(U110) 균계를 이용하였다. 뿌리분할장치의 양분된 뿌리에 독립적으로 접종하였으며 처리당 4반복씩 완전임의로 배치하였다. 균계간 경합을 보기 위하여 4조합의 근류균계들을 분할장치 양측에 동시 접종하였으며, 또한 균계간 상호작용을 보기 위하여 6조합의 균계를 반분된 뿌리의 양측에 1주일 간격으로 접종하였다. 접종후 3주만에 근류착생 정도와 생육을 조사하였으며 그 결과를 요약하면 다음과 같다. 1. Lee품종에서는 분할된 뿌리 양쪽에 P205만 접종되었을 때 근류중이 가장 작았던 반면 Pe-king 품종에서는 P205만 접종되었을 때 근류중이 가장 컸다. 2. 두 균계를 동시에 접종했을 때 Lee 품종에서는 UlIO에 대해 P205의 경합력이 거의 없었으나 Peking 품종에서는 오히려 P205의 경합력이 더 높은 것으로 나타났다. 3. 양 품종 모두 처리에 따른 뿌리의 생육은 차이가 없었으나 지상부 생육량에서는 Lee 품종의 경우 P205만 처리되었을 때 현저히 적었으며 Peking 품종은 P205 단독처리에 비해 U110 단독처리시 적었다. 4. P205를 1차 접종했을 때 Lee품종의 경우 2차 접종된 side의 근류수와 근류중을 현저히 감소시켰는데 다만 U110의 근류수에는 영향을 주지 않았으며, Peking품종에서는 근류수에 미치는 영향은 적었으나 근류중은 상당히 억제하였다. 5. U110을 1차 접종했을 경우에는 두 품종 공히 반대편 side의 근류착생을 심하게 저해하였다. 6. Lee 품종의 경우 1차 접종된 균계가 2차 접종된 side의 뿌리생육을 다소 억제하였으나 처리간 차이가 있었으며 근류착생이 불량했던 P205 처리구에서도 뿌리의 생육은 양호하였다. 반면에 Poking 품종에서는 거의 차이를 나타내지 않았다. 7. 지상부 생육은 Lee품종의 경우 U110 1차 접종구가, Peking 품종에서는 P205 1차 접종구에서 양호하였다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1155-1156
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• 2006

Hopkinson bar dynamic test under strain rates ranging from 2000 $s^{-1}$ to 8000 $s^{-1}$ at room temperature revealed that the flow stress of tungsten heavy alloys depended strongly on the strain, strain rate, and the content of molybdenum. The variation of flow stress was caused by the competition between work hardening and heat softening in the materials at different strain rates. The high temperature strength of the matrix phase was increased by the addition of molybdenum, which enhanced the strength of the tungsten heavy alloys in high strain rate test.

• Applied Biological Chemistry
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• 제48권3호
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• pp.296-300
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• 2005

Among the root colonizing and plant growth promoting bacteria isolated from the bacterial wilt suppressive soil, five strains were detected to produce siderophores by CAS agar assay. The most effective isolate, TS3-7 strain induced significant suppression of bacterial wilt disease in tomato and pepper plants. Seed treatment followed by soil drench application with this strain resulted in over 80% reduction of bacterial wilt disease compared with the control. Significant disease suppression by TS3-7 strain was related to the production of siderophore. Besides iron competition, induction of resistance of the host plant with siderophore was suggested to be another mode of action that suppress bacterial wilt, based on the lack of direct antibiosis against pathogen in vitro. According to Bergey's Manual of Systemic Bacteriology and 16S rDNA sequence data, TS3-7 stain was identified as Pseudomonas sp. TS3-7.

• 한국자동차공학회논문집
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• 제6권4호
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• pp.166-177
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• 1998

Combustion characteristics of natural gas premixed flames is studied experimently and numerically by adopting a counterflow as a flamelet model in turbulent flames. Flame speeds are measured by employing LDV, and the results show that flame speed increases linearly with strain rate, which agrees well with numerical results. Parametric dependences of extinction strain rates are studied numerically with detailed kinetic mechanism to show that the addition of ethand to a methane premixed flame makes the flame more resistant to strain rate. The effect of pressure on the extinction strain rate is that the extinction strain rate increases up to 10 atm and them decreases, which is explained by competition of chain branching H+O2=OH+O and recombination reaction H+O2+M=HO2+M. Detailed mechanism having seventy-four step is systematically reduced to a nine-step and a five-step thermal NOx chemistry is reduced to two-step. Comparison between the results of the detailed and the reduced mechanisms demonstrates that the reduced mechanism successfully describes the essential features of natural gas premixed flames including extinction strain rate and NOx production.

• 한국초전도ㆍ저온공학회논문지
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• 제24권2호
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• pp.19-22
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• 2022

We studied the effect of substrate-induced strain state on the superconducting transition in GdBa₂Cu₃O_7-x(GdBCO)/La_0.7Sr_0.3MnO₃ (LSMO) bilayers deposited on a LaAlO₃ (LAO) substrate. The stain state of LSMO is controlled by increasing the thickness from 20 nm to 80 nm. Analyses on the extended X-ray absorption fine structure (EXAFS) measurements reveal difference in the direction of MnO₆ octahedral distortion depending on the LSMO thickness, which leads to a difference in anisotropy of magnetization of LSMO layer. The superconducting transitions of our system are strongly correlated with the magnetic anisotropy accompanied by the MnO₆ octahedron distortion in a specific direction. This result suggests the possibility of improving the superconducting transition in the GdBCO/LSMO bilayer system by controlling the degree of competition between superconductivity and ferromagnetism via adjusting strain state in the LSMO layer.

• 대한금속재료학회지
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• 제48권4호
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• pp.305-314
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• 2010

The development of textures and microstructures during plastic deformation in a hot-extruded AZ 31 Mg alloy was investigated using a compression test with such parameters as deformation temperature, strain rate. It was observed from true stress-strain curves that twinning involves changes of the flow stresses. In the early stages of deformation at temperatures lower than $200^{\circ}C$, the occurrence of twins resulted in a decrease of the work-hardening rate, which increased drastically at a true strain of -0.05. The evolution of the deformation textures were assessed with the aid of EBSD analyses in terms of the competition between twinning and slip activity.

• 환경생물
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• 제31권2호
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• pp.61-68
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• 2013

Microalgae can grow autotrophically with the supply of light, carbon dioxide and inorganic nutrients in water through photosynthesis. Generally, microalgal growth is limited by the concentrations and relative ratio of nitrogen (N) and phosphorus (P) among the nutrients in the aquatic environment. Each microalga has its specific optimum N : P ratio resulting in dominance in a particular water having similar nutrient composition. Algal bloom is an immense growth of certain microalga commonly cyanobacterium and can be sequestrated by reducing the limiting nutrient, generally P in the freshwater. Moreover, dominance of a less toxic blooming strain can be established by manipulating N : P ratio in the water. On the other hand, microalgal biomass of a certain species can be enhanced by increasing limiting nutrient and adjusting the N : P ratio to the target species. The above-mentioned eco-physiological features of microalgae can be more completely interpreted in connection with their genomic informations. Consequently, microalgal growth regulation which can be achieved on the basis of its eco-physiological and further genomic insights would be helpful not only in the control of algal bloom, but also for an increased yield of algal biomass.

• 한국진공학회지
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• 제7권3호
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• pp.237-241
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• 1998

In-situ X-선 산란 방법을 이용하여 R.F. 스퍼터링 방법에 의하여 성장시킨 AIN/Si(111)박막의 우선성장과 표면 거칠기의 성장 시간에 따른 변화를 연구하였다. 대부분 의 성장 조건하에서 초기의 AIN박막은 <001> 우선 성장 방위를 가지고 성장하였다. 하지 만 박막의 두께가 증가함에 따라 우선 성장 방위가 많이 바뀌었는데 이 현상은 높은 기판 온도와 높은 R.F. power에서 더욱 뚜렷이 나타났다. 이러한 현상은 <001> 성장 방위를 선 호하는 표면 에너지와 우선 성장 방위의 무질서도를 증가하게 하는 응력(strain)에너지에 관 련된 것으로 해석된다. 이 실험에서는 X-선 반사율을 측정하여 성장 도중의 표면 현상 또 는 연구하였다.

• 소성∙가공
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• 제15권2호
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• pp.118-125
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• 2006

API steel is used for line-pipe to transport the oil and natural gas. As the recent trends in the development of API steel are towards the use of larger diameter and thicker plate, many researches have been studied to achieve higher strength, higher toughness and lower yield ratio in API steel. However, the strength of API steel after pipe forming is changed depending on the competition of the Bauschinger effect and work hardening which are affected by the strain history during pipe forming process. So, the purpose of this study is to investigate the influence of microstructure on the Bauschinger effect for API steel. To change the microstructure of API steel we have changed the hot rolling condition and the amounts of V and Cu addition. The compression-tensile test and the microstructure observation by OM and TEM were conducted to investigate the yield strength drop and the correlation between the Bauschinger effect and microstructure of API steel. The experimental results show that the increase of polygonal ferrites volume fraction increases the Baushcinger effect due to the back stress which comes from the increase of mobile dislocation density at polygonal ferrite interior during the compressive deformation. The hot rolling condition was more effective on the Bauschinger effect in API steel than the small amount of V and Cu addition.