• Journal of the Korean Society of Visualization
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• v.3 no.1
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• pp.63-70
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• 2005

Optical Line Patternator(OLP) has been applied to get a distribution of the spray at high ambient pressure. OLP is a combined technique of extinction measurement and image processing. The attenuated intensity of laser beam after traversing spray region was measured by using a photo-detector, and the line image of Mie-scattering was captured simultaneously in the path of each laser beam by using a CCD camera. The distribution of extinction coefficient in the spray is obtained by processing these data with the algebraic reconstruction technique. From the distribution of extinction coefficient, the surface distribution of spray can be reconstructed. OLP does not use laser sheet but use laser beam so that the noise effect of multiple scattering, caused by increasing number density of droplet in high pressure environment, is reduced drastically. OLP is expected as a suitable method which can investigate the characteristics of relatively large spray under the high pressure environment such as liquid rocket engine.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.396-402
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• 2006

An efficient spline boundary element scheme is newly developed for water wave scattering of an incident wave train on a submerged breakwater. Validation of the present scheme is accomplished through the numerical experiments for various cases, by comparing the numerical results with theories vailable in the literature. Very accurate reflection and transmission coefficients for thin horizontal breakwater are obtained. It is observed that the reflection coefficient for the rectangular breakwater is significantly affected by the thickness. Horizontal and vertical forces on the breakwater for various thicknesses were also investigated.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.12
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• pp.65-73
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• 1995

In this paper, new algorithm which calculates transmission coefficient of electromagnetic wave by numerical analysis of scattered field by conductors with arbitrary cross-sections in parallel-plate waveguide is proposed. Proposed algorithm assumes magnetic current distribution on the boundary of scattering conductors, and applies Image theorem to perfect conductor surfaces of parallel-plate waveguide. Integral equations for fictitious magnetic currents on conducting boundary are set up. Magnetic current distributions on conducting boundary are expanded as exponential basis function, and using Galerkin method matrix equations are set wp. To compute matrix elements this method utilizes Fourier transform which is faster than numerical integration. Finally, frequency and incidence-angle characteristic of transmission coefficient are calculated and compared with experimental results.

• Journal of Information Display
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• v.10 no.2
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• pp.72-75
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• 2009

The Brillouin spectrum of 4'-n-pentyl-4-cyano-biphenyl (5CB) liquid crystals homogeneously confined in a planar liquid crystal (LC) cell was measured using a 6-pass tandem Fabry-Perot interferometer. By adopting a special right-angle scattering geometry, the sound velocity of 5CB was estimated from the Brillouin shift without knowing the refractive index. The sound velocity of the longitudinal wave propagating along the direction of the directors aligned parallel to the glass plates of the LC cell was 1784${\pm}$7 m/s at 300 K. The attenuation coefficient $\alpha$ was estimated to be approximately $1.9{\times}10^6m^{-1}$, which is about twice as large as that of the longitudinal sound wave propagating along the direction perpendicular to the directors. The present method may be very useful in the evaluation of the elastic properties of the materials used in display devices, whose refractive indices are not known.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.243.2-243.2
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• 2016

Tungsten (W) is recently gaining attention as a potential candidate to replace Cu in semiconductor metallization due to its expected improvement in material reliability and reduced resistivity size effect. In this study, the impact of electron scattering at grain boundaries in a polycrystalline W thin film was investigated. Two nominally 300 nm-thick films, a (110)-oriented single crystal film and a (110)-textured polycrystalline W film, were prepared onto (11-20) Al2O3 substrate and thermally oxidized Si substrate, respectively in identical fabrication conditions. The lateral grain size for the polycrystalline film was determined to be $119{\pm}7nm$ by TEM-based orientation mapping technique. The film thickness was chosen to significantly exceed the electron mean free path in W (16.1 and 77.7 nm at 293 and 4.2 K, respectively), which allows the impact of surface scattering on film resistivity to be negligible. Then, the difference in the resistivity of the two films can be attributed to grain boundary scattering. quantitative analyses were performed by employing the Mayadas-Shatzkes (MS) model, where the grain boundary reflection coefficient was determined to be $0.42{\pm}0.02$ and $0.40{\pm}0.02$ at 293 K and 4.2 K, respectively.

• Journal of the Korean Applied Science and Technology
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• v.23 no.4
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• pp.340-346
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• 2006

The influences of fluorescence, scattering, and flocculation in turbid material by light scattering were interpreted for the scattered fluorescence intensity and wavelength, it has been studied the molecular properties by the spectroscopy of laser induced fluorescence (LIF). The effects of optical properties in scattering media have been found by the optical $parameters({\mu}_s,\;{\mu}_a,\;{\mu}_t)$. Flocculation is an important step in many solid-liquid separation processes and is widely used. When two particles approach each other, interactions of several colloid particles can come into play which may have major effect on the flocculation and LIF process, The value of scattering coefficient ${\mu}_s$ is large by means of the increasing particles of scatterer it has been found that the slope decays exponentially as a function of distance from laser source to detector. It may also aid in designing the best model for oil chemistry, biopharmaceutical products, laser medicine and application of medical engineering on LIF and coagulation in particle transport mode.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2004.11a
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• pp.178-179
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• 2004

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2004.11a
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• pp.419-420
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• 2004

• Proceedings of the Optical Society of Korea Conference
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• 2005.02a
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• pp.334-335
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• 2005

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.304.2-304.2
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• 2014

Chalcogenides (Te,Se) and pnictogens(Bi,Sb) materials have been widely investigated as thermoelectric materials. Especially, Bi2Te3 (Bismuth telluride) compound thermoelectric materials in thin film and nanowires are known to have the highest thermoelectric figure of merit ZT at room temperature. Currently, the thermoelectric material research is mostly driven in two directions: (1) enhancing the Seebeck coefficient, electrical conductivity using quantum confinement effects and (2) decreasing thermal conductivity using phonon scattering effect. Herein we demonstrated influence of annealing temperature on structural and thermoelectrical properties of Bismuth-telluride-selenide ternary compound thin film. Te-rich Bismuth-telluride-selenide ternary compound thin film prepared co-deposited by thermal evaporation techniques. After annealing treatment, co-deposited thin film was transformed amorphous phase to Bi2Te3-Bi2Te2Se1 polycrystalline thin film. In the experiment, to investigate the structural and thermoelectric characteristics of Bi2Te3-i2Te2Se1 films, we measured Rutherford Backscattering spectrometry (RBS), X-ray diffraction (XRD), Raman spectroscopy, Scanning eletron microscopy (SEM), Transmission electron microscopy (TEM), Seebeck coefficient measurement and Hall measurement. After annealing treatment, electrical conductivity and Seebeck coefficient was increased by defect states dominated by selenium vacant sites. These charged selenium vacancies behave as electron donors, resulting in carrier concentration was increased. Moreover, Thermal conductivity was significantly decreased because phonon scattering was enhanced through the grain boundary in Bi2Te3-Bi2Te2Se1 polycrystalline compound. As a result, The enhancement of thermoelectric figure-of-merit could be obtained by optimal annealing treatment.