• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.141-144
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• 2001

An accurate cross sections set are necessary for the quantitatively understanding and modeling of plasma phenomena. By using the electron swarm method. we determine an accurate electron cross sections set for objective atoms or molecule at low electron energy range. In previous paper, we calculated the electron transport coefficients in pure $CF_4$ molecular gas by using two-term approximation of the Boltzmann equation. And by using this simulation method. we confirmed erroneous calculated results of transport coefficients for $CF_{4}$ molecule treated in this paper having 'C2v symmetry' as $C_{3}H_{8}$ and $C_{3}F_{8}$ which have large vibrational excitation cross sections which may exceed elastic momentum transfer cross section. Therefore, in this paper, we calculated the electron transport coefficients(W and $ND_L$) in pure $CF_4$ gas by using multi-term approximation of the Boltzmann equation by Robson and Ness which was developed at lames-Cook university, and discussed an application and/or validity of the calculation method by comparing the calculated results by two-term and multi-term approximation code.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 추계학술대회 논문집
• /
• pp.141-144
• /
• 2001

An accurate cross sections set are necessary for the quantitatively understanding and modeling of plasma phenomena. By using the electron swarm method, we determine an accurate electron cross sections set for objective atoms or molecule at low electron energy range. In previous paper, we calculated the electron transport coefficients in pure CF$_4$ molecular gas by using two-term approximation of the Boltzmann equation. And by using this simulation method, we confirmed erroneous calculated results of transport coefficients for CF$_4$ molecule treated in this paper having 'C2v symmetry'as C$_3$H$_{8}$ and C$_3$F$_{8}$ which have large vibrational excitation cross sections which may exceed elastic momentum transfer cross section. Therefore, in this paper, we calculated the electron transport coefficients(W and ND$_{L}$) in pure CF$_4$ gas by using multi-term approximation of the Boltzmann equation by Robson and Ness which was developed at James-Cook university, and discussed an application and/or validity of the calculation method by comparing the calculated results by two-term and multi-term approximation code.e.

• Current Optics and Photonics
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• 제6권1호
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• pp.79-85
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• 2022

Tracers are one of the critical factors for improving the performance of velocimetry. Silver and gold nanoparticles as tracers with localized surface-plasmon resonance are analyzed for their scattering properties. The scattering cross sections, angular distribution of the scattering, and equivalent scattering cross sections from 53° and 1.5° half-angle cones at 532 nm are calculated, with particle sizes in the nanoscale range. The 53° and 1.5° half-angle cones used as examples correspond respectively to the collection cones for microscope objectives in microscopic measurements and camera lenses in macroscopic measurements. We find that there is a transitional size near 35 nm when comparing the equivalent scattering cross sections between silver and gold nanoparticles in water at 532 nm. The equivalent scattering cross section of silver nanoparticles is greater or smaller than that of gold nanoparticles when the particle radius is greater or smaller than 35 nm respectively. When the radius of the plasmonic nanoparticles is smaller than about 44 nm, their equivalent scattering cross sections are at least ten times that of TiO₂ nanoparticles. Plasmonic nanoparticles are promising for velocimetry applications.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
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• pp.1165-1168
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• 2005

We review discharge characteristics of fluorescent lamps having noncircular cross sections. The developmental and theoretical history of noncircular cross-section lamps is summarized chronologically. In particular, discharge characteristics of noncircular cross-section lamps will be summarized and analyzed including plasma contraction, electron temperature, and ambipolar diffusion loss, which might give us some insights into the way to develop more efficient and uniform flat fluorescent lamps, which have recently arisen as a new light source of large-size backlight units for LCD TV applications.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
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• pp.175-182
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• 2001

Effective length factor approach for framed column design has long played an important design-aid role. This approach, however, is effective only when the columns are in the form of prismatic or uniform cross sections. Structural engineers who have to design or analyse framed columns with variable cross sections need some means to do their job. By using the finite element method, the stability analysis of the isolated compression members with variable cross sections and that of the framed columns are performed. The parameters considered in the stability analysis are taper and sectional property parameters of the columns, the second moment of inertia ratio of beam to column, and beam span to column height ratio. On the basis of the stability analysis results, effective length factor formulas for the columns with variable sections are derived.

• Steel and Composite Structures
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• 제38권3호
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• pp.257-270
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• 2021

This paper presents a displacement-based numerical methodology following the Euler-Bernoulli theory to simulate the 2 nonlinear behavior of steel structures. It is worth emphasizing the adoption of co-rotational finite element formulations considering large displacements and rotations and an inelastic material behavior. The numerical procedures proposed considers plasticity concentrated at the finite elements nodes, and the simulation of the steel nonlinear behavior is approached via the Strain Compatibility Method (SCM), where the material constitutive relation is used explicitly. The SCM is also applied in determining the sections bearing capacity. Moreover, the present numerical approach is not limited to a specific structural member cross-sectional typology, with the residual stress models introduced explicitly in subareas of steel cross-sections generated by a 2D discretization. Finally, results consistent with the literature and with low processing time are presented.

• Steel and Composite Structures
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• 제18권4호
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• pp.985-1000
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• 2015

The method of cross-section analysis for different sections in a structural frame has been widely investigated since the 1960s for determination of sectional capacities of beam-columns. Many hand-calculated equations and design graphs were proposed for the specific shape and type of sections in pre-computer age decades ago. In design of many practical sections, these equations may be uneconomical and inapplicable for sections with irregular shapes, leading to the high construction cost or inadequate safety. This paper not only proposes a versatile numerical procedure for sectional analysis of beam-columns, but also suggests a method to account for residual stress and geometric imperfections separately and the approach is applied to design of high strength steels requiring axial force-moment interaction for advanced analysis or direct analysis. A cross-section analysis technique that provides interaction curves of arbitrary welded sections with consideration of the effects of residual stress by meshing the entire section into small triangular fibers is formulated. In this study, two doubly symmetric sections (box-section and H-section) fabricated by high-strength steel is utilized to validate the accuracy and efficiency of the proposed method against a hand-calculation procedure. The effects of residual stress are mostly not considered explicitly in previous works and they are considered in an explicit manner in this paper which further discusses the basis of the yield surface theory for design of structures made of high strength steels.

• Transactions on Electrical and Electronic Materials
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• 제2권1호
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• pp.7-11
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• 2001

We measured the electron transport coefficients, the electron drift velocity, W, and the longitudinal diffusion coefficient, $D_{L}$, over the E/N range from 0.03 to 100 Td and gas pressure range from 0.133 to 122 kPa in the 0.526% and 5.05% $C_{3}F_{8}$-Ar mixtures by the double shutter drift tube with variable drift distance. And we calculated these electron transport coefficients by using multi-term approximation of Boltzmann equation analysis. We determined the electron collision cross sections set for $C_{3}F_{8}$ molecule by the comparison of measurement and calculation. Our special attention in the present study was focused upon the inelastic collision cross sections of the $C_{3}F_{8}$ molecule.

• Nuclear Engineering and Technology
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• 제31권6호
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• pp.631-637
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• 1999

The module LEAPR of NJOY data processing system has been improved to have the capability of computing the thermal elastic scattering cross sections for silicon, which has a diamond-like structure. Silicon lattice was assumed as an fcc lattice with two atoms at each lattice point. The calculation formulas for thermal neutron elastic scattering by silicon were introduced and incorporated into LEAPR, and then the scattering cross sections for silicon were computed. The results were compared with experimental data, and they were found to give a good agreement with experimental data.

• Steel and Composite Structures
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• 제7권6호
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• pp.441-456
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• 2007

In literature for thin-walled sections with L, [, +, I, and ${\Box}$- shapes the approximate torsion equations for stiffness are used which were proposed by Bach (Hsu 1984), p.30. New formulae for torsional stiffness of bars with L, [, +, I, and ${\Box}$ cross section valid not only for thin-walled sections are presented in this paper. These formulae are obtained by appropriate polynomial approximation of stiffness results obtained by means of method of fundamental solutions. On the base of obtained results the validity of Bach's formulae are verified when cross section is not thin-walled.