• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.302-304
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• 2002

In linac-based stereotactic radiosurgery, assuring the quality of the planning and delivery of external photon beam requires accurate evaluation of beam parameters, usually including output factors, tissue-phantom ratio and off-axis ratios, and measurement of actual dose distributions from simulated treatment. We're going to test the use of calibrated radio chromic film (Gafchromic film; type MD-55, Nuclear associate) using a Lumiscan 75 digitizer to measure absolute dose and relative dose distributions for linac-based radiosurgery unit Relative dose distribution of a human-style spherical acryl phantom were measured using radiochromic film and calculated by treatment planning system. The absolute dose at the sphere center was measured by radiochromic film and micro chamber (Exradin A-14, 0.009cc). What we want to demonstrate in this work, the 'well selected' radiochromic films when external photon beam are used in linac-based stereotactic radiosurgery are very accurate detector for dosimetry.

• Food Science and Biotechnology
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• v.15 no.6
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• pp.925-930
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• 2006

Chitosan-based nanocomposite films were prepared using a solution intercalation method incorporating varying amounts of organically modified montmorillonite (Cloisite 30B) from 0 to 30 wt%. The nanocomposite films prepared were optically clear despite a slight decrease in the transmittance due to the spatial distribution of nanoclay. X-ray diffraction patterns indicated that a certain degree of intercalation or exfoliation formed when the amount of clay in the film was low and that microscale tactoids formed when the clay content in the sample was high (more than 10 wt%). The tensile strength (TS) of the chitosan film increased when the clay was incorporated up to 10 wt% and then decreased with further increases in the clay content of the film. The elongation at break (E) increased slightly upon the addition of low levels of clay up to 5 wt% and then decreased with further increases in the amount of the clay in the film. The water vapor permeability (WVP) decreased exponentially with increasing clay content. The water solubility (WS) and swelling ratio (SR) of the nanocomposite films decreased slightly, indicating that the water resistance of the chitosan film increased due to the incorporation of the nanoclay.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.10
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• pp.74-80
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• 2009

This paper presents a study on fluid flow analysis of organic semiconductor thin film deposition process using the computational numerical method. In the production process, the thickness of deposited organic thin film depends on distribution of nozzle size in the linear cell system, so we analyze to decide the optimal nozzle system for uniform thickness of organic thin film. The results of deposited thickness of thin film by numerical analysis are in good agreement with those of the experimental measurements.

• Mass Spectrometry Letters
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• v.12 no.1
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• pp.26-30
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• 2021

The impurity concentration is a crucial parameter for semiconductor thin films. Evaluating the impurity distribution in silicon thin film is another challenge. In this study, we have investigated the doping concentration of boron in silicon thin film using time of flight secondary ion mass spectrometry in dynamic mode of operation. Boron doped silicon film was grown on i) p-type silicon wafer and ii) borosilicate glass using hot wire chemical vapor deposition technique for possible applications in optoelectronic devices. Using well-tuned SIMS measurement recipe, we have detected the boron counts 101~104 along with the silicon matrix element. The secondary ion beam sputtering area, sputtering duration and mass analyser analysing duration were used as key variables for the tuning of the recipe. The quantitative analysis of counts to concentration conversion was done following standard relative sensitivity factor. The concentration of boron in silicon was determined 1017~1021 atoms/㎤. The technique will be useful for evaluating distributions of various dopants (arsenic, phosphorous, bismuth etc.) in silicon thin film efficiently.

• Journal of the Korea Convergence Society
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• v.10 no.9
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• pp.133-140
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• 2019

The Korean Film Council which manages the Film Development Fund carried out a number of projects to support film production, distribution, and film policies. Also, this organization participated in promoting advanced film technology and foreign film location by constituting an incentive support. The projects consist of support for the operation of Namyangju filming studio and the film information system as well. It is necessary to scrutinize the projects regarding support for film production, which is the largest and most important among the whole projects, for continuous development of the Korean film industry. this study reviwed the fundraising status, budget, and support projects of the Center for National Film/Video Center CNC which operates the film fund in France analyzed film production support policy of the CNC. Through this, we verified necessity of stable financing and funding of the Korean Film Development Fund, support for creation of film music and support for overseas filming, and prepared activation plans for film co-production.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.12
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• pp.996-1003
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• 2002

Heat transfer characteristics were investigated for the falling film flowing down the outside of an electrically heated vertical tube. Water was used for the falling film, and its Reynolds number was varied in the range of 70～500. Because water is heated and evaporated as it flows down, both sensible and latent heat transfer should be considered. The effect of the surrounding air movement was investigated by changing the direction of the air injection; without air injection, parallel-flow, and counter-flow. For all cases, sensible teat transfer rate was almost linearly increased with the increasing film flow rate. It was found that the film heat transfer coefficient was hardly influenced by the parallel air flow. However, the counter-flow of air reduced the heat transfer coefficient, which might be caused by the uneven distribution or flooding of the film. At high heat flux, a sudden change of the film heat transfer coefficient was detected as the film flow rate reached the transition value. It is supposed that this phenomenon was caused by the change in the film flow pattern.

• Tribology and Lubricants
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• v.24 no.1
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• pp.21-26
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• 2008

A pin bush bearing is one of the most important element in the piston engine which is joined a piston to a connecting rod. A pin bush is suffered by heat and changeable repeat loads, which are come from the explosive gas heat and pressures during a reciprocating stroke. Therefore, a tribological behavior of pin bush bearings is very severe compared to other parts of a piston assembly. To keep a stable operation of pin bush bearings effectively, it would be satisfied with proper oil film strength for severe operating conditions and durability, which are strongly related to the oil film thickness, oil film pressure, and a friction loss power. The computed results show that the viscosity of engine oils slightly affects to the minimum oil film thickness and oil film pressure distribution, but is an influential parameter on a total friction loss power. Thus the low viscosity engine oils for an increased operation condition should select a high level of base oil and add a viscosity index improver as an oil film additive.

• Transactions of the Korean hydrogen and new energy society
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• v.1 no.1
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• pp.48-54
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• 1989

Semiconductive property of the passivating $TiO_2$ film was investigated by measuring the impedance of passivated titanium electrode in a 0.1 N NaOH solution. The passive film was prepared galvanostatically with $10mA/cm^2$ at formation potential of 50 V in a 1 N $H_2SO_4$ solution. The impedance measurement was conducted by superimposing an ac voltage of 5 m V amplitude with the frequency ranging from 5 to 10000 Hz on a dc bias (applied potential). The donor distribution in the film was depicted from the analysis of the non-linear slope of Mott-Schottky plot. The region with nearly constant concentration of donors near the electrolyte/film interface amounts at about 60 percent of the total film thickness and donor concentration increases largely with distance from the surface in an inner region near the film/metal interface. In a region of the film/metal interface the donor concentration showed a frequency dependence greater than in a region of the electrolyte/film interface. The result of donor concentration against frequency suggests a transition from crystalline to amorphous state with distance from the electrolyte/film interface in the passivating $TiO_2$ films. This is also confirmed by the ac conductivity measurement.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.8
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• pp.753-758
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• 2005

A flux-lock type superconducting fault current limiter(SFCL) consists of two coils, which are wound in parallel each other through an iron core, and a high-$T_c$ Superconducting(HTSC) thin film connected in series with coil 2. If the current of the HTSC thin film exceeds its critical current by the fault accident, the resistance of the HTSC thin film generated, and thereby the fault current can be limited by the impedance of the fluk-lock type SFCL. In this paper, we investigated the dependence of both the fault current limiting characteristics and the current distribution between two coils on the operational current of the flux-lock type SFCL through the equivalent circuit analyses and short circuit tests. From the comparison of both the results, the experimental results well agreed with the analyses for equivalent circuit.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.1975-1981
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• 1991

A new numerical solution of the elastohydrodynamic lubrication(EHL) problem of an axially profiled cylindrical roller is presented. A finite difference method and the Newton-Raphson method are used to solve the nonlinear system equations. A non-uniform grid system is adopted to reduce the number of grid points and to obtain accurate solution. For two different types of profiles which have similar elastostatic pressure distribution, the EHL results show large differences. Especially the difference in film shape is larger than in pressure distribution. Therefore, the magnitude of the minimum film thickness should be a major criteria to design the axial profile of the roller. Variations of the minimum film thickness with dimensionless parameters show considerably different behavior from those of infinite solution and show a good agreement with the experimental data in literatures. Present numerical scheme can be used generally in the analysis of three-dimensional EHL problem.