• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.8
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• pp.104-108
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• 2008

Accurate sets of electron collision cross sections and the electron transport coefficients for atoms and molecules are necessary for quantitative understanding of plasma phenomena Kr and Xe atom are used in many industrial applications, such as in PDP and fluorescent induction lamps(FILs). Therefore, we analysed and calculated the electron transport coefficients, the electron drift velocity W, the longitudinal and transverse diffusion coefficient $ND_L$ and $ND_T$, and the ionization coefficient $\alpha$/N in pure Kr and Xe gases over the wide E/N range from 0.001 to 500[Td] at 1[Torr] by two-tenn approximation of the Boltzmann equation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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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 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.1
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• pp.67-73
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• 1998

In this paper, the electron swarm parameters in the 0.5% and 0.2% SF\ulcorner+Ar mixtures are measured by time of flight method over the E/N(Td) range from 30 to 300(Td). The measurements have been carried out by the double shutter drift tube with variable drift distance from the cathod. A two-term approximation of the boltzmann equation analysis and Monte Carlo simulation have been also used to study electron transport coefficients. We have calculated W, $ND_L,\;ND_T,\;\alpha,\;\eta,\;\alpha-\eta$, and the limiting breakdown electric field to gas mixtures ratio in pure $SF_6$+Ar mixtures. The electron energy distribution function has been analysed in $SF_6$+Ar mixtures at E/N : 200(Td) for a case of the equilibrium region in the mean electron energy. The measured results and the calculated results have been compared each other.

• The Journal of Korean Society for Radiation Therapy
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• v.8 no.1
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• pp.29-35
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• 1996

We are often faced with the clinical situations that is inevitably extended SSD for electron beam therapy due to anatomical restriction or applicator structure. But there are some difficulties in accurately predicting output and properties. In electron beam treatment , unlike photon beam the decrease in output for extended SSD does not follow inverse-square law accurately because of a loss of side scatter equilibrium, which is particularly significant for small cone size and low energies. The purpose of our study is to analyze the output in changing with the energy, cone size, air gap beyond the standard SSD and to compare inverse-square law factor derived from calculated effective SSD, mominal SSD with measured output factor. In addition, we have analyzed the change of PDD for several cones with different SSDs which range from 100cm to 120cm with 5cm step and with different energies(6MeV, 9MeV, 12MeV, 16MeV, 20MeV). In accordance with our study, an extended SSD produces a significant change in beam output, negligible change in depth dose which range from 100cm to 120cm SSDs. In order to deliver the more accurate dose to the neoplastic tissue, first of all we recommend inverse-square law using the table of effective SSDs with cone sizes and energies respectively or simply to create a table of extended SSD air gap correction factor. The second we need to have an insight into some change of dose distribution including PPD, penumbra caused by extended SSD for electron beam therapy.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.823-826
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• 2001

In the initial process of photosynthesis, a biological electron transfer system, photoelectric conversion occurs and then long-range electron transfer takes place very efficiently in one direction through the biomolecules. The metal/insulator/metal structured device consisting of GFP, viologen, cytochrome c hetero-thin film was presented based on the biomimesis. GFP, viologen, and cytochrome c was used as an electron sensitizer, a mediator, and an electron acceptor. Cytochrome c molecules and viologen molecules were deposited by Langmuir-Blodgett (LB) technique, and GFP molecules were adsorbed by self-assembly method (SAM). Surface morphology of hetero-thin film was analyzed by scanning tunneling microscopy (STM). Local photoswitching effects of a proposed photodiode were verified by current-voltage measurements using hybrid STM/I-V measurement system.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.236-238
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• 2003

The electron transport coefficients, the electron drift velocity W, the longitudinal diffusion coefficient $ND_L$ and $D_L/\mu$, in pure Ne were calculated over the wide E/N range from 0.01 to 800 Td at 1 Torr by two-term approximation of the Boltzmann equation for determination of electron collision cross sections set and for quantitative characteristic analysis of Ne molecular gas.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.2
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• pp.146-150
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• 2010

Distribution Function and Drift velocities for electrons in $SF_6$-Ar mixtures gases used by MCS-BEq algorithm has been analysed over the E/N range 30~300[Td] by a two term Boltzmann equation and by a Monte Carlo simulation using a set of electron cross sections determined by other authors, experimentally the electron swarm parameters for 0.2[%] and 0.5[%] $SF_6$-Ar mixtures were measured by time-of-flight method. The results obtained in this work will provide valuable information on the fundamental behaviors of electrons in weakly ionized gases and the role of electron attachment in the choice of better gases and unitary gas dielectrics or electro negative components in dielectric gas mixtures. The results show that the deduced electron drift velocities agree reasonably well with theoretical for a rang of E/N values.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1734-1737
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• 2015

Insulating characteristics of Cl₂-He mixture gases in gas discharges were analysed to evaluate ability of these gases for using in medium voltage and many industries. These are electron transport coefficients, which are the electron drift velocity, density-normalized longitudinal diffusion coefficient, and density-normalized effective ionization coefficient, in Cl₂-He mixtures. A two-term approximation of the Boltzmann equation was used to calculate the electron transport coefficients for the first time over a wide range of E/N (ratio of the electric field E to the neutral number density N). The limiting field strength values of E/N, (E/N)_lim, for these binary gas mixtures were also derived and compared with those of the pure SF₆ gas.

• Journal of radiological science and technology
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• v.22 no.2
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• pp.53-56
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• 1999

A Gaussian distribution was parametrized for the initial distribution of the electron beam emitted from a 6MeV medical linear accelerator. A percent depth dose was measured in a water phantom and the corresponding Monte Carlo calculations were performed starting from a Gaussian distribution for a range of standard deviations, ${\sigma}=0.1$, 0.15, 0.2, 0.25, and 0.3 with being the mean value for the Incident beam energy. When measurement and calculation were compared, the calculation with the Gaussian distribution for ${\sigma}=0.25$ turned out to agree best with the measurement. The results from the present work can be utilized as input energy data in planning an electron beam therapy with a Monte Carlo calculation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.5
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• pp.1087-1091
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• 1999

Microwave extraction system equipped with closed vessels, which is known to rapidly extract target compounds from natural products, was applied to monitor the changes in phenolic compounds, browning color intensity and electron donating ability by using response surface methodology(RSM). Maximum content of phenolic compound was 21.65mg/100ml in 67.88% of ethanol concentration, 145oC of extraction temperature, and 6.24min of extraction time. The phenolic compounds in extracts are dependent on the increase of the extraction temperature and the ethanol concentration. Browning color intensity, which was maximized in 67.21%, 147oC, and 6.02min, was proportional to the increase of the extraction temperature. Maximum value of electron donating ability was 24.50units in 54.33%, 147oC, and 6.11 min. The electron donating ability of extracts was dependent on the increase of extraction temperature and maximized in the range from 50 to 65% of ethanol concentration.