• 한국세라믹학회지
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• 제29권9호
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• pp.739-749
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• 1992

The sols prepared by dialyzing solutions, in which the hydrolyzed precipitates of TEOT or directly Ti(OC3H7)4 were resolved, were the nanoparticulate sol with the average particle size less than 7 nm and the anatase crystal phase. In the pH range of 1.5 to 2.9, the particle size of the nanoparticulate TiO2 sols (0.09 mol/ι) increased gradually upto 15 nm~26nm with the increase of pH in the initial aging state but the sols were transparent all the time, and stable without growin any more after 30 days. When the slipcasted porous alumina tubes were coated by the sol-gel dipping method, the minimum particle size and the aging time for forming the coated gel layer at the given pH were optimized. For obtaining the very thin crack-free and reproducible membrane coating, the use of a nanoparticulate TiO2 sol (0.09 mol/ι) aged for about 30 dyas at pH=2.0 was found to be the best.

• 한국디지털건축인테리어학회논문집
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• 제11권2호
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• pp.31-39
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• 2011

Concrete-filled steel tube(CFT) columns have become popular for building construction due to not only composite effect of steel tube and infilled concrete, but also more economical. The purpose of this paper is to propose the applicable boundary formula of width-to-thickness ratio for rectangular steel tube as using CFT column. A parametric study was performed taking width-to-thickness ratio of rectangular steel tube and compressive strength of concrete as the main parameter. The strength of concrete are selected to 30, 60, 90MPa. The non-linear analysis was adopted in order to take into account the effect of concrete strength. Finally, from the test and analysis results, the effect of increasing strength according to concrete strength and width-to-thickness of steel tube and plastic behavior of specimens were verified distinctly.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.7-7
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• 2010

Indium tin oxide (ITO) - SWNT nano crystalline composites was synthesized at low temperature(${\sim}250^{\circ}C$)using Nano Cluster Deposition technique by Metal Orhoganic Chemical Vapor Deposition method. XRD patterns of ITO- SWNT composite shows pure cubic phases without any secondary phase. I-V measurement gives resistance of 12 ohms for Sn doped (3 wt %) indium oxide-SWNT composites. The electrical conductivity of the nano composites is significantly enhanced compared to the SWNT.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.69-69
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• 2010

Carbon nano tubes (CNTs) have been attractive candidates for fundamental research studies due to their outstanding physical and chemical properties. High thermal and chemical stability and large surface area make CNTs an ideal platform for many nano materials systems. Several applications such as Several applications were proposed for CNTs many of which are concerned with conductive or high strength composites make them excellent candidates for a variety of energy conversion and storage technologies.

• Carbon letters
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• 제13권4호
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• pp.248-253
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• 2012

Dielectrophoretic filtering and alignment of single-walled carbon nanotubes (SWCNTs) were tested using deuterium oxide as a solvent. A solution of deuterium oxide-SWCNTs was dropped on top of a silicon chip and an ac electric field was applied between pre-defined electrodes. Deuterium oxide was found to be a better solvent than hydrogen oxide for the dielectrophoresis process with higher efficiency of filtering. This was demonstrated by comparing Raman spectra measured on the initial solution with those measured on the filtered solution. We found that the aligned nanotubes along the electric field were not deposited on the substrate but suspended in solution, forming chain-like structures along the field lines. This so-called pearl chain formation of CNTs was verified by electrical measurements through the aligned tubes. The solution was frozen in liquid nitrogen prior to the electrical measurements to maintain the chain formation. The current-voltage characteristics for the sample demonstrate the existence of conduction channels in the solution, which are associated with the SWCNT chain structures.

• Steel and Composite Structures
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• 제22권5호
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• pp.1073-1084
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• 2016

Rectangular concrete-filled steel tubular columns with unequal wall thickness were investigated in the paper. The physical centroid, the centroidal principal axes of inertia, and the section core were given. The generalized bending formula and the generalized eccentric compression formula were deduced, and the equation of the neutral axis was also provided. The two rectangular concrete-filled steel tubular stub specimens subjected to the compression load on the physical centroid and the geometric centroid respectively were tested to verify the theoretical formulas.

• Steel and Composite Structures
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• 제34권4호
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• pp.599-613
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• 2020

In this article, free vibration attributes of double-walled carbon nanotubes based on nonlocal elastic shell model have been investigated. For this purpose, a nonlocal Flügge shell model is established to observe the small scale effect. The wave propagation is employed to frame the governing equations as eigenvalue system. The influence of nonlocal parameter subjected to different end supports has been overtly examined. A suitable choice of material properties and nonlocal parameter been focused to analyze the vibration characteristics. The new set of inner and outer tubes radii investigated in detail against aspect ratio and length. The dominance of boundary conditions via nonlocal parameter is shown graphically. The results generated furnish the evidence regarding applicability of nonlocal shell model and also verified by earlier published literature.

• Steel and Composite Structures
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• 제37권5호
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• pp.621-632
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• 2020

This research deals with the study of vibrational behavior of armchair and zigzag single-walled carbon nanotubes invoking extended Love shell theory. The effects of different physical and material parameters on the fundamental frequencies are investigated. By using volume fraction for power law index, the fundamental natural frequency spectra for two forms of single-walled carbon nanotubes are calculated. The influence of frequencies against length-to-diameter ratios with varying power law index are investigated in detail for these tubes. To discretize the governing equation in eigen-value form, wave propagation approach is developed. Complex exponential functions have been used and the axial model depends on boundary condition that has been described at the edges of carbon nanotubes to calculate the axial modal dependence. Computer software MATLAB is utilized for the frequencies of single-walled carbon nanotubes and current results shows a good stability with comparison of other studies.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.317-320
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• 2006

In order to determine a minimum thickness of the pultruded GFRP panel as a structural member, some experimental studies were performed. GFRP tubes with 2mm, 4mm, 6mm thickness were manufactured by pultrusion process. First, coupon tests for finding mechanical properties were carried out. Comparisons between test results and analysis results based on classical laminate theory showed large differences in case of 2mm, 4mm specimens. The reason is that it is difficult to apply appropriate pultruding force and keep layered stitched fabric flat for the pultrusion process of complex shaped FRP member with small thickness. On the consequence, we decide 6mm as a minimum thickness of FRP member. Second, 4-point bending tests were performed and the results with compared with numerical analysis. The behavior of FRP tube can be exactly predicted by numerical analysis if buckling analysis is included.

• Steel and Composite Structures
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• 제38권3호
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• pp.305-317
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• 2021

The mechanical behavior of the outer square inner circular concrete-filled dual steel tubular (SCCFT) stub columns under axial compression is investigated by means of experimental research, numerical analysis and theoretical investigation. Parameters such as diameter ratio, concrete strength and steel ratio were discussed to identify their influence on the mechanical properties of SCCFT short columns on the basis of the experimental investigation of seven SCCFT short columns. By establishing a finite element model, nonlinear analysis was performed to discuss the longitudinal and transverse stress of the dual steel tubes. The longitudinal stress characteristics of the core and sandwich concrete were also analyzed. Furthermore, the failure sequence was illustrated and the reasonable cross-section composition of SCCFT stub column was proposed. A formula to predict the axial load capacity of SCCFT stub column was advanced and verified by the results from experiment and the finite element.