12,748 research outputs found
고용체의 열역학적 성질 및 결함구조에 관한 연구
No full text학위논문(박사) - 한국과학기술원 : 원자력공학과, 1995.2, [ vii, 109 p. ]The oxygen potentials have been measured by means of a thermogravimetric method in the range of and atmosphere for pure , and U_{1-y}Er_yO_{2\pmx} solid solutions with y=0.02, y=0.06 and y=0.20, respectively. Their oxygen partial pressures were maintained by controlling /CO mixture atmosphere, and the values corresponding to x of solid solutions were measured with an electrolyte oxygen sensor. The lattice parameter of the stoichiometric was also determined with use of X-ray diffraction data in the range of y=0.01 to y=0.33. The lattice parameter decreases linearly with an increase in the erbium content. The change of the lattice parameter can be expressed in a linear equation of y as a(\mbox{\AA})=5.4695-0.220y for . The has been found to undergo abrupt increase in the range of -270 to -360 kJ/mole for y=0.06 and -220 to -320 kJ/mole for y=0.20, respectively, in the temperature range of . The differences in between the values at O/(U+Er)=1.999 and 2.001 decrease with increasing temperature. The values as a function of temperature for the stoichiometric composition are expressed by (kJ/mole) = -423.43 + 0.089T for and (kJ/mole) = -422.00 + 0.125T for . increases with erbium content, but the effect of the dopant for x=0.01 is less significant than that for stoichiometry. Both and for showed higher values as increasing y, and sharp maxima at the O/M ratio of approximately 2.005, irrespective of erbium content. The oxygen potentials for and can be approximately r...한국과학기술원 : 원자력공학과
Liquid‐to‐Solid Phase Transitions of Imidazolium‐Based Zwitterionic Polymers Induced by Hofmeister Anions
No full textIn this study, we compared the responses of two different types of zwitterionic polymers (ZPs), polyvinylimidzole sulfobetaine (poly(SBVI)) and polymethacrylate sulfobetaine (poly(SBMA)) to Hofmeister anions. Although the anions of the two ZPs were the same as the sulfonate anions and only the types of their cations were different from each other, the aggregation behavior of each in the salt aqueous solution was remarkably different. Consequently, poly(SBVI) exhibited both salting-in and salting-out effects depending on the type and concentration of salt, while poly(SBMA) only exhibited the anti-polyelectrolyte effect. The results of this study provide a deeper understanding of the behavior of zwitterionic polymers in salt solutions and will greatly expand their applications.11Nsciescopu
A study on the posture stabilization of single leg robot
No full text학위논문(석사) - 한국과학기술원 : 기계공학전공, 2003.2, [ v, 60 p. ]한국과학기술원 : 기계공학전공
FlexGNN: A High-Performance, Large-Scale Full-Graph GNN System with Best-Effort Training Plan Optimization
No full textRecently, full-graph Graph Neural Networks (GNNs) have gained prominence by addressing complex problems such as weather forecasting and material discovery. Existing full-graph training methods do not fully manage intermediate data generated during training and rely on rigid inter-GPU communication, limiting both training speed and scale. We propose FlexGNN, which fully manages intermediate data and adaptively performs inter-GPU communication by generating and optimizing best-effort training execution plans. Extensive experiments demonstrate that FlexGNN significantly outperforms existing full-graph GNN methods in both training speed and scale. Specifically, it is up to 5.4X faster than HongTu and up to 95.5X faster than NeutronStar
Non-linear dynamical analysis of the EEG in Alzheimers disease with optimal embedding dimension
No full textWe used non-linear analysis to investigate the dynamical properties underlying the EEG in patients with Alzheimer's disease. We calculated the correlation dimension D2 and the first positive Lyapunov exponent L1. We employed a new method, which was proposed by Kennel et al., to calculate the non-linear invariant measures. That method determined the proper minimum embedding dimension by looking at the behavior of nearest neighbors under a change in the embedding dimension d from d to d + 1. We demonstrated that for limited noisy data, our algorithm was strikingly faster and more accurate than previous ones. Also, we found that, in almost all channels, patients with Alzheimer's disease had significantly lower D2 and L1 values than those for age-approximated healthy controls. These results suggest that brains afflicted by Alzheimer's disease show behaviors which are less chaotic than those of normal healthy brains. In this paper, we show that non-linear analysis can provide a fruitful tool for detecting relative changes, which cannot be detected by conventional linear analysis, in the complexity of brain dynamics. We propose that non-linear dynamical analyses of the EEGs from patients with Alzheimer's disease will be a diagnostic modality in the appropriate clinical setting. (C) 1998 Elsevier Science Ireland Ltd.This research was supported by the G7-project from the
Ministry of Science and Technology, the Biotech 2000 project,
and the ’96 Chungbuk National University Hospital
Research Fund. We thank Dr. Dae-jin Kim, Dr. Jung-ho
Chae, and Mr. J. Lee at St. Mary’s Hospital in Taejon
for experimental help during this study. The authors are
also thankful for the fruitful comments of the unknown
referees
Deposition of fluorinated amorphous carbon thin films as a low-dielectric-constant material
No full textFluorinated amorphous carbon thin films (a-C:F) are deposited using inductively coupled plasma chemical vapor deposition with various flow-rare ratios of CH4:CF4 gases for ultralarge-scale integrated intermetal dielectric applications. The accurate composition of the thin films are quantitatively analyzed using elastic recoil detection-time of flight. The incorporation of fluorine is saturated at about 25 atom % by increasing the CF4 flow rate. The dielectric constant decreases to 2.4 and the refractive index of the film is reduced to 1.35 as the CF4 flow rate increases. Also, it is observed that the C-F bonding configuration changes from an unsaturated C-F bond to C-F-2 and C-F-3 bonds with growing CF4 flow rate. Thus, the reduction mechanism of the dielectric constant can be obtained by variation of the C-F, bonding configuration as well as the incorporation of fluorine. (C) 1999 The Electrochemical Society. S0013-4651(98)11-028-5. All rights reserved.This work was financially supported by the Ministry of Education through the Interuniversity Semiconductor Research Center(ISRC 97-E-1060) in Seoul National University and by the International Collaborative Research Program of the Ministry of Science and Technology.
Korea Advanced Institute of Science and Technology assisted in meeting the publication costs of this article
Infrared and Raman spectra of 4-cyanobenzoic acid on powdered silver
No full textWe have attempted to record the infrared and Raman spectra of 4-cyanobenzoic acid (4CBA) adsorbed on 2-mu m-sized silver particles. The diffuse reflectance infrared Fourier transform (DRIFT) spectrum taken for the sample was little different from the reflection-absorption infrared (RAIR) spectrum taken for the same molecules on vacuum-evaporated thick silver films, suggesting that the usual surface selection rule should be applicable even to the surface of fine metal particles. The Raman spectrum of 4CBA on powdered silver was a surface-enhanced Raman (SER) spectrum, exhibiting little difference from that taken on vacuum-evaporated thin, rough silver films. Thus, the commercially available powdered silver seemed to be an efficient substrate for the infrared and Raman spectroscopic characterization of molecular adsorbates prepared in a similar way on silver surfaces. (C) 1999 Elsevier Science B.V. All rights reserved
Chopping effect on the crystallinity of ZnO films prepared by a rf planar magnetron sputtering method
No full textWe have investigated the chopping effect on the crystallinity of the ZnO films prepared by using a modified rf planar magnetron sputtering method, where the sputtering process is periodically chopped. In the experiment we have found that if the deposition and pause time is chosen optimally for the renucleation of ZnO grains, a highly c-axis-oriented ZnO film with a large crystallite size can be grown on the SiO2/Si(100) substrate
Nanocomposite hydrogel actuators hybridized with various dimensional nanomaterials for stimuli responsiveness enhancement
Get PDFHydrogel actuators, that convert external energy, such as pH, light, heat, magnetic field, and ion strength, into mechanical motion, have been utilized in sensors, artificial muscles, and soft robotics. For a practicality of the hydrogel actuators in a wide range of fields, an establishment of robust mechanical properties and rapid response are required. Several solutions have been proposed, for example, setting porous and anisotropy structures to hydrogels with nanocomposite materials to improve the response speed and deformation efficiency. In this review paper, we focused on hydrogel actuators including various nanocomposite by categorizing the dimensional aspects of additive materials. Moreover, we described the role of diverse additive materials in terms of the improvement of mechanical property and deformation efficiency of the hydrogel actuators. We assumed that this review will provide a beneficial guidance for strategies of developing nanocomposite hydrogel actuators and outlooks for the future research directions.11Ysciescopu
Generation of a Nrf2 homozygous knockout human embryonic stem cell line using CRISPR/Cas9
Get PDFNuclear factor erythroid 2-related factor 2 (NFE2L2 or Nrf2) is a well-known transcription factor that regulates the expression of a large number of anti-oxidant genes in mammalian cells (J.H. Kim et al., 2014). Here, we generated a homozygous Nrf2 knockout human embryonic stem cell (hESC) line, H9Nrf2KO-A13, using the CRISPR/Cas9 genome editing method. The Nrf2 homozygous knockout H9 cell line maintains pluripotency, differentiation potential into three germ layers, and a normal karyotype
- …
