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排序方式: 共有653条查询结果,搜索用时 46 毫秒
31.
Byung-Hak Choe Soo-Keun Shin Sung-Joon Kim Yong-Tai Lee S. B. Kang Masuo Hagiwara 《Metals and Materials International》2005,11(6):429-433
The effects of aging treatment on the microstructures and mechanical properties of a metastable beta titanium alloy Ti-15-3
(Ti−15V−3Al−3Sn-3Cr) have been investigated with hardness measurements, tensile test, and optical and electron microscopy.
Precipitate-free beta structure with average grain size of about 56 μm was obtained after solution treatment at 800°C for
15 min followed by air cooling. Solution treated specimens were aged up to 800 h in the temperature range between 350 and
600°C. The morphology of the precipitates was varied significantly, depending on the aging temperature. The fine aggregates
of α precipitates were dominant above 450°C. Peak hardness values were maintained up to 800 h at 500°C, which showed the superior
thermal stability of α precipitates. Tensile strength increased up to 1600 MPa along with the decrease of elongation after
aging at 350 and 400°C. 相似文献
32.
Jeongah Song Kyung-Jin Jung Mi-Jin Yang Woojin Kim Byoung-Seok Lee Seong-Kyu Choe Seong-Jin Kim Jeong-Ho Hwang 《International journal of molecular sciences》2022,23(6)
Polyhexamethylene guanidine phosphate (PHMG-P), a cationic biocide, is widely used in household products due to its strong bactericidal activity and low toxicity. However, it causes fatal lung damage when inhaled. In this study, we investigated why PHMG-P causes fatal lung injury when inhaled, and demonstrated that the disruption of membrane integrity through ionic interaction—a molecular initiating event of PHMG-P—determines toxicity. Mice were injected intravenously with 0.9 or 7.2 mg/kg PHMG-P (IV group), or instilled intratracheally with 0.9 mg/kg PHMG-P (ITI group); they were euthanatized at 4 h and on days 1 and 7 after treatment. Increased total BAL cell count and proinflammatory cytokine production, along with fibrotic changes in the lungs, were detected in the ITI group only. Levels of hepatic enzymes and hepatic serum amyloid A mRNA expression were markedly upregulated in the 7.2 mg/kg IV and ITI groups at 4 h or day 1 after treatment, but returned to baseline. No pathological findings were detected in the heart, liver, or kidneys. To simulate the IV injection, A549, THP-1, and HepG2 cells were treated with PHMG-P in cell culture media supplemented with different serum concentrations. Increased serum concentration was associated with an increase in cell viability. These results support the idea that direct contact between PHMG-P and cell membranes is necessary for PHMG-induced toxicity. 相似文献
33.
Development of a microbial time-temperature integrator system using lactic acid bacteria 总被引:1,自引:0,他引:1
Seong Hwan Lim Woo Yeong Choe Byung Hyun Son KwangWon Hong 《Food science and biotechnology》2014,23(2):483-487
A microbial time-temperature integrator (TTI) system was developed using lactic acid bacteria (Weissella koreensis) obtained from baechukimchi. Activation energy (Ea), which represents the temperature dependence of the TTI response, was calculated using the Arrhenius equation. Ea values for the color change (ΔE value), maximum specific growth rate (μmax), and pH change of the TTI measured under different isothermal conditions (5, 10, 15 and 20°C) were 99.88, 95.91, and 93.38 kJ/mol, respectively. According to the time taken to reach the TTI endpoint by the initial inoculum level of W. koreensis (6.2, 5.5, 4.5, and 3.4 log CFU/mL), a negative correlation was observed in 63.5, 101.8, 115.1 and 166.6 h. In addition, initial bacterial counts decreased significantly up to almost 4% at 20°C in 3 months when W. koreensis viability was measured at the freezing point of the microbial TTI system (20 and ?80°C) for 1 week, 1 month, 2 months, and 3 months. However, viability was about 95% at 80°C. This microbial TTI system would be useful to monitor the quality of food with similar Ea values during storage or distribution. 相似文献
34.
Autonomous agents traversing a natural space need to be knowledgeable of its space configuration. The existing space models in geographic information systems and robotics, however, deal with only the topological relations among numerous types of spatial relations. We aim to develop an enhanced space model that elaborates the spatial relations with respect to their relevant physical relations. Specifically, the spatial relations in a space configuration are further characterized with the gravitation as a potential factor to affect the space configuration. The resulting space model is capable of capturing an extended set of spatial relations over existing models such as a four‐intersection model. © 2005 Wiley Periodicals, Inc. Int J Int Syst 20: 867–892, 2005. 相似文献
35.
Md. Dulal Hossain Junghoon Moon Hyoung Goo Kang Sung Chul Lee Young Chan Choe 《Scientometrics》2012,90(1):57-83
Triple helix (TH) collaborations involving university, industry and government provide a networked infrastructure for shaping
the dynamic fluxes of knowledge base of innovations locally and these fluxes remain emergent within the domains. This study
maps these emergence dynamics of the knowledge base of innovations of Research & Development (R&D) by exploring the longitudinal
trend of systemness within the networked research relations in Bangladesh on the TH model. The bibliometric data of publications
collected from the Science Citation Index (SCI), the social sciences and the arts and humanities for analysis of science indicators
and the patent data collected from the US Patent Office to analyze the patent success ratio as a measure of innovation within
TH domains. The findings show that the network dynamics have varied considerably according to the R&D policies of the government.
The collaboration patterns of co-authorship relations in the SCI publications prominently increased, with some variation,
from 1996 to 2006. Nevertheless, inter-institutional collaboration negatively influenced by the national science and technology
(S&T) research policies in the last 5 years due to their evaluation criteria. Finally, the findings reveal that the R&D system
of Bangladesh is still undergoing a process of institutionalizing S&T and has failed to boost its research capacity for building
the knowledge base of innovations by neglecting the network effects of TH dynamics. 相似文献
36.
Ri Choe Hyojin Cho Taejin Park Kwang Ryel Ryu 《Journal of Intelligent Manufacturing》2012,23(6):2179-2192
To maximize the productivity of a container terminal, the operations of various types of equipments should be optimized and synchronized in real time. However, use of optimization techniques such as mathematical programming or search-based meta-heuristics becomes difficult when given a large-scaled problem due to their high computational cost. Addressing this problem, the queue-based local scheduling and global coordination method proposed in this paper stands as a viable alternative. The method consists of the following steps. First, separate schedules are locally generated for each equipment type using a queue-based dispatching heuristic which pays attention to the queue lengths of the quay cranes (QCs) under service. Next, the schedules are executed via a simulation and a notable QC delay is identified. Based on the analysis on the causes of this delay, some compromising adjustments are made to the priorities of relevant jobs. Then, the localized scheduling followed by the adjustment is repeated until the termination condition is met. Adopting simple heuristics in the local scheduling phase, the overall process easily meets the real-time constraint, yet producing an integrated schedule with a better global perspective than the myopic heuristic-only approach. 相似文献
37.
Lee JI Kim JL Chang SY Nam YM Chung KS Choe HS 《Radiation protection dosimetry》2002,100(1-4):341-344
Three-dimensional thermoluminescence (TL) spectra based on temperature, wavelength and intensity for newly developed LiF:Mg,Cu,Na,Si TL material at the Korea Atomic Energy Research Institute (KAERI) were measured and analysed. The glow curves were obtained by integration of luminescence intensity over all wavelengths at each temperature, and various trapping parameters related to the traps were determined by analysing these curves. A computerised glow curve deconvolution (CGCD) method which was based on the general order kinetics (GOK) model was used for the glow curve analysis. The glow curves of LiF:Mg,Cu,Na,Si TL material were deconvoluted to six isolated glow curves which have peak temperatures at 333, 374, 426, 466, 483 and 516 K. The main glow peak of peak temperature at 466 K had activation energy of 2.06 eV and a kinetic order of 1.05. This TL material was also found to have three recombination centres, 1.80 eV, 2.88 eV and 3.27 eV by analysis of the TL spectra. 相似文献
38.
We employ a static analysis to examine the extensivity (∀x:x≤f(x)) of functions defined over lattices in a λ-calculus augmented with lattice operations. The need for such a verification procedure
has arisen in our work on a generator system (called Zoo) of static program-analyzers. The input to Zoo is a static analysis
specification that consists of lattice definitions and function definitions over the lattices. Once the extensivity of the
functions is ascertained, the generated analyzer is guaranteed to terminate when the lattices have finite-heights. The extensivity
analysis consists of a sound syntax-driven deductive rules whose satisfiability check is done by a constraint solving procedure.
Hyunjun Eo: He is a Ph.D. candidate of Computer Science Dept. at KAIST (Korea Advanced Institute of Science and Technology). He received
his B.S. and M.S. in Computer Science from KAIST in 1996 and 1998, respectively. For 1998–2003, he was a research assistant
of the National Creative Research Initiative Center for Research On Program Analysis System. His research interest has been
on static program analysis, program logics, and higher-order and typed languages. He is currently working on developing a
tool for automatic generation of program analyzers.
Kwangkeun Yi, Ph.D.: His research interest has been on semantic-based program analysis and systems application of language technologies. After
his Ph.D. from University of Illinois at Urbana-Champaign he joined the Software Principles Research Department at Bell Laboratories,
where he worked on various static analysis approaches for higher-order and typed programming languages. For 1995–2003, he
was a faculty member in the Department of Computer Science, Korea Advanced Institute of Science and Technology. Since Fall
2003, he has been a faculty member in the School of Computer Science and Engineering, Seoul National University.
Kwang-Moo Choe, Ph.D.: He is a professor of Computer Science at Korea Advanced Institute of Science and Technology. He received his B.S. from Seoul
National University in 1976, and his M.S. and Ph.D. from Korea Advanced Institute of Science and Technology in 1978 and 1984,
respectively. For 1985–1986, he was a technical staff of AT&T Bell Labs at Murray Hill. His research interest is formal language
theory, parallel evaluation of logic programs, and optimizing compilers. 相似文献
39.
OBJECTIVE: To determine if either dopamine or dobutamine would counteract the deleterious effect that positive end-expiratory pressure (PEEP) has on cardiac output and mesenteric blood flow in a rat model of acute lung injury. DESIGN: Prospective, randomized, controlled trial in a clinically relevant model of acute lung injury. SETTING: Microcirculation research laboratory. SUBJECTS: Male Sprague-Dawley rats. INTERVENTIONS: The animals were anesthetized with pentobarbital (30 mg/kg) by intraperitoneal injection. They underwent tracheostomy, jugular and femoral vein cannulation, femoral artery cannulation, carotid artery thermistor placement, and bowel preparation for in vivo video microscopy. Acute lung injury was created by administering 0.1 N hydrochloric acid (1 mL/kg) via the tracheostomy. Dopamine or dobutamine (2.5 or 12.5 microg/kg/min), followed by two intravenous fluid boluses, was administered to rats ventilated with 5, 10, 15, and 20 cm H2O of PEEP. MEASUREMENTS AND MAIN RESULTS: Mean arterial pressure, thermodilution cardiac output, mesenteric arteriolar diameter, and red blood cell velocity were measured and mesenteric blood flow was calculated. Cardiac output was depressed in rats exposed to 20 cm H2O of PEEP by 32+/-2%. The corresponding values for cardiac output depression at 20 cm H2O of PEEP in rats receiving 2.5 and 12.5 microg/kg/min of dopamine and 2.5 and 12.5 microg/kg/min of dobutamine were 31+/-1%, 21+/-1%, 29+/-0%, and 24+/-2%, respectively. Mesenteric blood flow was depressed in rats ventilated with 20 cm H2O of PEEP by 74+/-3%, while the corresponding values in rats exposed to 20 cm H2O of PEEP and receiving 2.5 or 12.5 microg/kg/min of dopamine or 2.5 or 12.5 microg/kg/min of dobutamine were 86+/-3%, 77+/-3%, 73+/-3%, and 66+/-3%, respectively. Fluid boluses did not correct the deficits in cardiac output or mesenteric blood flow caused by the combination of acute lung injury and PEEP. CONCLUSIONS: The higher doses of dopamine and dobutamine partially, but insignificantly, corrected the cardiac output depression caused by PEEP in a model of acute lung injury. Neither dose of dopamine nor dobutamine was able to improve PEEP-induced mesenteric blood flow depression. 相似文献
40.