• Bulletin of the Korean Chemical Society
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• 제18권9호
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• pp.1006-1010
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• 1997

The nature and analysis methods of complicated decay profiles found in forced Rayleigh scattering (FRS) have been investigated for the probe diffusion of methyl yellow in 2-propanol. The complementary shifted and ground state grating effect, which is known to be the origin of non-single exponential decays, was analyzed by non-linear regression fitting to a double exponential model function. We confirmed that the parameters were highly correlated so that it was difficult to extract a unique set of parameters in the presence of experimental noise. Nevertheless, a reasonable range of decay time constants could be estimated from the grating spacing dependence.

• 천문학회보
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• 제37권2호
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• pp.210.2-210.2
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• 2012

Using Fresnel reflection and Hapke BRDF model with Apollo 10084 soil sample's scattering properties, we constructed a real scale optical lunar model and used it to simulate lunar apparent albedo and moonshine. For Fresnel reflection, the refractive index of $1.68{\pm}0.5$ was used. For Hapke BRDF parameters from BUGs BRDF measurement, the single scattering with w=0.33, hot spot width h=0.017, average phase angle ${\zeta}$=-0.086 and Legendre polynomial coefficients b=0.308, c=0.425 in wavelength 700nm with two types of Henyey-Greenstein phase function was applied. The computation model includes the Sun as a Lambertian scattering sphere, emitting 1.5078 W/m2 at 700nm in wavelength. The Sun and Moon models were then imported into the IRT based radiative transfer computation. The trial simulation of the irradiance levels of moonshine lights shows that they agree well with the ROLO measurement data. We then estimate the lunar apparent albedo to 0.11. The results are to be compared with the measurement data.

• Journal of Mechanical Science and Technology
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• 제15권12호
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• pp.1801-1807
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• 2001

In multiphase flne the bubble size and velocity. To achieve this, one of approaches is to utilize laser phase-Doppler anemometry. However, it was found that the second order refraction has great impact on PDA sizing method when the relative refractive index of media is less than one. In this paper, the problem of second order refraction is investigated and a model of phase-size correlation to eliminate the measurement errors is introduced for bubble sizing. As a result, the model relates the assumption of single scattering mechanism in conventional phase-Doppler anemometry. The results of simulations based on this new model by using Generalized Lorenz Mie Theory (GLMT) are compared with those based on the conventional method. An optimization method for accurately sizing air-bubble in water has been suggested.

• 한국진공학회지
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• 제2권2호
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• pp.171-180
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• 1993

X-선 광전자 분광법(XPD)을 이용하여 GaAs(110) 절개면의 결정구조를 이해하였다. 각분해 X-선 분광법으로 GaAs(110) 면의 내각준위 Ga 및 As 3d의 스펙트럼을 얻어, 이 내각 준위의 세기 비율(intensity ratio)의 방위각과 편각에 따른 변화를 SSC(Single Scattering Cluster) 모델에서 얻은 회절패턴으로 곡선분석(fitting)하여 절개면의 재구성 구조(reconstruction geometry)를 얻었다. 이 절개면의 재구성된 값은 다른 실험의 결과와 비슷하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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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.

• Nuclear Engineering and Technology
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• 제45권4호
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• pp.529-538
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• 2013

Scattered photons cause blurring and distortions in flash radiography, reducing the accuracy of image reconstruction significantly. The effect of the scattered photons is taken into account and an iterative deduction of the scattered photons is proposed to amend the scattering effect for image restoration. In order to deduct the scattering contribution, the flux of scattered photons is estimated as the sum of two components. The single scattered component is calculated accurately together with the uncollided flux along the characteristic ray, while the multiple scattered component is evaluated using correction coefficients pre-obtained from Monte Carlo simulations.The arbitrary geometry pretreatment and ray tracing are carried out based on the customization of AutoCAD. With the above model, an Iterative Procedure for image restORation code, IPOR, is developed. Numerical results demonstrate that the IPOR code is much more accurate than the direct reconstruction solution without scattering correction and it has a very high computational efficiency.

• Bulletin of the Korean Chemical Society
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• 제12권4호
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• pp.387-392
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• 1991

We present a theoretical investigation of the inelastic atom-surface phonon scattering for a model He-Si(100) system by the classical trajectory-quantum forced oscillator(DECENT) method. Single and multi-phonon transition probabilities of normal modes are calculated for several initial beam orientations and several initial kinetic energies. In order to understand surface structure effects, the calculation has been done on both reconstructed and unreconstructed surfaces of the He/Si(100) system. The origin of mode specificity for energy transfer is discussed. The contribution of one, two, and multi-phonon events to the total energy transfer between 0 and 600 K is also given.

• 지구물리와물리탐사
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• 제14권3호
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• pp.249-253
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• 2011

한반도 남동부지역 지진자료의 고유감쇠($Q_i^{-1}$)와 산란감쇠($Q_s^{-1}$)값을 바탕으로 다중산란모델에 의한 이론코다감쇠 값(${Q_{Cexp}}^{-1}$)을 구하고 단일산란 모델의 관측 코다감쇠값($Q_C^{-1}$) 및 고유 및 산란 감쇠상수 값($Q_i^{-1}$, $Q_s^{-1}$)과 비교하였다. 그 결과, ${Q_{Cexp}}^{-1}$ 값은 $Q_i^{-1}$값에 근접한 전형적인 모습이나, $Q_C^{-1}$값이 고주파수 대역을 제외한 대부분의 구간에서 ${Q_{Cexp}}^{-1}$ 값과 상이한 것으로 나타났다. 향후 이러한 연구는 깊이에 따라 변화하는 감쇠값을 고려하여 진행되어야 할 것이다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권3호
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• pp.1182-1194
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• 2016

The single image dehazing algorithm in existence can satisfy the demand only for improving either the effectiveness or efficiency. In order to solve the problem, a novel variational framework for single image dehazing based on restoration is proposed. Firstly, the initial atmospheric scattering model is transformed to meet the kimmel's Retinex variational model. Then, the green light component of image is considered as an input of the variational framework, which is generated by the sensitivity of green wavelength. Finally, the atmospheric transmission map is achieved by multi-resolution pyramid reduction to improve the visual effect of the results. Experimental results demonstrate that the proposed method can remove haze effectively with less memory consumption.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.538-541
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• 2005

Tidal flats develop along the south coast ofthe Korean peninsula. These areas are famous for sea farming. Specially, strong and coherent radar backscattering signals are observed over oyster sea farms that consist of artificial structures. Tide height in oyster farm is possible to measure by using interferometric phase and intensity of SAR data. It is assumed that the radar signals from oyster farm could be considered as double-bouncing returns by vertical and horizontal bars. But, detailed backscattering mechanism and polarimetric characteristics in oyster farm had not been well studied. We could not demonstrate whether the assumption is correct or not and exactly understand what the properties of back scattering were in oyster farm without full polarimetric data. The results of AIRSAR L-band POLSAR data, experiments in laboratory and JERS-l images are discussed. We carried out an experiment simulating a target structure using vector network analyser (Y.N.A.) in an anechoic chamber at Niigata University. Radar returns from vertical poles are stronger than those from horizontal poles by 10.5 dB. Single bounce components were as strong as double bounce components and more sensitive to antenna look direction. Double bounce components show quasi-linear relation with height of vertical poles. As black absorber replaced AI-plate in bottom surface, double bounce in vertical pole decreased. It is observed that not all oyster farms are characterized by double bounced scattering in AIRSAR data. The image intensity of the double bounce dominant oyster farm was investigated with respect to that of oyster farm dominated by single bounce in JERS-l SAR data. The image intensity model results in a correlation coefficient (R2 ) of 0.78 in double bounce dominant area while that of 0.54 in single bouncing dominant area. This shows that double bounce dominant area should be selected for water height measurement using In8AR technique.