• 한국가시화정보학회지
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• 제3권2호
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• pp.3-13
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• 2005

The optical patterantor provides the high resolution and quantitative information of the spray. Fuel distribution and Sauter Mean Diameter (SMD) can be measured from fluorescence and Mie-scat-tering images. To correct the attenuation of the laser beam and signal in dense spray region, the method to find the geometric mean of the signal intensities obtained from two cameras was evaluated and verified in a solid-cone spray. In high pressure environment, the increased number density of the droplets cause multiple scattering. The optical patternation technique using a laser beam instead of a laser sheet was applied to minimize the multiple scattering problem. The pattern of a coaxial spray was changed from hollow-cone to solid-cone shape, and the spray angle was reduced as the ambient pressure increased from 0.1 to 4.0 MPa.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 춘계학술대회
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• pp.235-239
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• 1996

In recent years, the optical properties of multiple-scattering media like tissue have been studied for their potential applications in medicine. In this work the optical properties of multiple scattering media were investigated using the time-resolved reflectance measurement. The reflected light was measured by time-correlated single photon counting system. The transport scattering and absorption coefficient are related to the initial rapid decay and the subsequent decay in reflected light, respectively. Also the optical properties of the samples were measured by conventional method, ie., using continuous wave light. When the distance between the light source and the detector is over 8mm, the optical coefficient can be measured accurately using the suggested method.

• Bulletin of the Korean Chemical Society
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• 제17권7호
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• pp.648-653
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• 1996

We have shown several examples of characterization of multicomponent polymer systems by size exclusion chromatography coupled with a light scattering detector. Although SEC cannot provide a complete information for such systems due to its intrinsic limitation, one can extend its capability by combining multiple detection in order to get relevant information to some extent.

• 천문학회지
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• 제53권6호
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• pp.169-179
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• 2020

Emission features formed through Raman scattering with atomic hydrogen provide unique and crucial information to probe the distribution and kinematics of a thick neutral region illuminated by a strong far-ultraviolet radiation source. We introduce a new 3-dimensional Monte-Carlo code in order to describe the radiative transfer of line photons that are subject to Raman and Rayleigh scattering with atomic hydrogen. In our Sejong Radiative Transfer through Raman and Rayleigh Scattering (STaRS) code, the position, direction, wavelength, and polarization of each photon is traced until escape. The thick neutral scattering region is divided into multiple cells with each cell being characterized by its velocity and density, which ensures flexibility of the code in analyzing Raman-scattered features formed in a neutral region with complicated kinematics and density distribution. To test the code, we revisit the formation of Balmer wings through Raman scattering of the far-UV continuum near Lyβ and Lyγ in a static neutral region. An additional check is made to investigate Raman scattering of O vi in an expanding neutral medium. We find a good agreement of our results with previous works, demonstrating the capability of dealing with radiative transfer modeling that can be applied to spectropolarimetric imaging observations of various objects including symbiotic stars, young planetary nebulae, and active galactic nuclei.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권6호
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• pp.2838-2858
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• 2019

Traditional channel models for vehicle-to-vehicle (V2V) communication usually assume fixed velocity in static scattering environment. In the realistic scenarios, however, time-variant velocity for V2V results in non-stationary statistical properties of wireless channels. Dynamic scatterers with random velocities and directions have been always utilized to depict the non-stationary statistical properties of the channel. In this paper, a non-stationary geometry-based cooperative scattering channel model is proposed for multiple-input multiple-output (MIMO) V2V communication systems, where a birth-death process is used to capture the appearance and disappearance dynamic properties of moving scatterers that reflect the time-variant time correlation and Doppler spectrum characteristics. Moreover, our model has more straight and concise to study the impact of the vehicular traffic density on channel characteristics and thus avoid complicated procedure in deriving the analytical expressions of the channel parameters and functions. The numerical results validate our analysis and demonstrate that setting important parameters of our model can appropriately build up more purposeful measurement campaigns in the future.

• 전산구조공학
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• 제10권2호
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• pp.213-223
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• 1997

탄성파의 변형 및 응력계산에 관한 연구는 비파괴검사를 비롯하여 광범위한 공학분야에서 중요한 역할을 하고 있다. 특히 파형의 산란문제가 많은 연구자들에 의해 다양한 방법으로 연구되고 있다. 실린더 또는 구와 같은 간단한 형상을 지닌 산란체에 대하여, 정상상태 탄성파의 산란문제의 해석은 해석적 기법을 이용한 연구가 가능하다. 하지만 임의의 형상을 갖는 산란체 또는 다수의 함유체에 대한 해석에는 수치해석방법이 요구된다. 예를 들면, 무한요소법 또는 Global-Local 유한요소법이라고 하는 혼성 유한요소법과 같은 특수한 유한요소법등이 개발되고 있다. 최근에는 경계요소법을 사용한 산란문제의 해석에 대한 연구가 진행되고 있다. 본 논문에서는 다수의 임의의 형상을 갖는 함유체, 공동 또는 크랙을 포함하고있는 무한고체에서의 일반적인 탄성동력학 문제를 해석하기 위해 새롭게 개발된 체적적분 방정식법을 소개한다. 또한 경계요소법을 사용하여 탄성파의 산란문제에 대한 수치해석을 수행하였으며, 이의 결과를 체적적분 방정식법의 결과와 비교 검토 하였다.

• 한국광학회지
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• 제3권3호
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• pp.161-166
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• 1992

회전하는 거친금속표면에 s-편극된 레이저광을 $-30^{\circ}$로 입시시켜 생긴 후방산란파중 입사광과 동일한 편극을 가지는 후방산란파에 대하여 세기의 시간상관함수 $g_{s}^{(2)}(\tau)$를 측정하였다. 이 과정에서 광전신호로부터 $g_{s}^{(2)}(0)$의 측정을 할 때 수반되는 shot noise의 영향을 제하여 줌으로써 정확한 $g_{s}^{(2)}(0)$ 값을 얻었다. 각 산란각$\theta_{s}$에서$g_{s}^{(2)}(\tau)$는 {1+exp($-\tau^2/\tau_0^2$)}함수와 거의 일치하였는데, 이는 등속으로 회전하는 간유리를 투과하여 형성된 레이저 스펙클의 경우와 같은 결과이다. 또한, 산란각에 따른 $\tau_0$의 분포에서는 $\theta_s=34^{\circ}$에서 예리하게 최대값을 가지는 것이 관찰되었다. 이 연구에서, 다중산란이 10%를 넘는 금속판산란과 다중산란이 무시될 수 있는 간유리판산란이 같은 함수꼴의 세기의 시간상관함수를 갖는다는 사실이 확인되었다.

• 한국환경과학회지
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• 제9권5호
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• pp.385-388
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• 2000

Visibility reduction is a barometer of air pollution which people can notice easily. First of all we need to measure quantified visibility continuously in order to examine visibility reduction. Prevailing visibility is not practical to measure visibility depending on observer's expertness. Scattering visibility using Forward Scattering Meter(Belfort Visibility Sensor 6230) has been measured at Kwangan-Dong in Pusan and analysed since July 1998. According to the analysis the correlation coefficient(R) between prevailing visibility and scattering visibility was 0.7235. The visibility appeared that each frequency of poor visibility(under 6km) and good visibility(over 25km) was 10.6%, 9.7% on summertime in Pusan and the visibility range from 10km to 20km ranked high frequency as a half of whole ranges. The order of correlation coefficients between visibility an air pollutants are ranking CO. PM10 and NO2 that values are 0.5878, 0.5369,l 0.5284 respectively. In meteorolgical factor the case of poor visibility presented more weakly wind speed and higher relative humidity than the case of good visibility. The correlation coefficient between calculated visibility of multiple linear regression model and observed visibility was 0.7215. But the trend of calculated and observed visibility variation was similar with the exception of several good visibility cases.

• 자원리싸이클링
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• 제26권1호
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• pp.43-50
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• 2017

본 연구에서는 무기질 첨가재를 혼합한 천연수경성석회의 초기경화 거동분석을 위해 multiple light scattering 분석법을 이용하였다. 자체 제조한 천연수경성석회의 물성향상을 위해 고로수쇄슬래그 및 3종류의 석고를 혼합비에 따라 혼합하였으며 물-고체비 0.6으로 페이스트를 제조하였다. 제조한 페이스트를 이용하여 원통형의 용기에 일정량을 담아 장비(Turbiscan LAB, Formulaction)에 장입하여 분석을 실시하였다. 페이스트로부터의 backscattering flux(BS, %)는 $23^{\circ}C$의 온도에서 분석용기 전체높이(55 mm)에 대해 24시간 동안 10분 간격으로 측정되었다. 모든 시료에서 전체적으로 BS는 시간경과에 따라서 증가하는 경향성을 보였다. 고로수쇄슬래그와 석고를 첨가함에 따라서 시간에 따른 BS의 증가 속도는 0.02에서 0.38 BS %/hour 까지 증가하였다. 반수석고를 혼합하였을 경우 가장 높은 backscattering flux와 BS의 증가속도를 보였다.

• 천문학회보
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• 제41권1호
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• pp.49.3-50
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• 2016

Two major radiative transfer (RT) techniques have been developted to model late-type galaxies: approximate RT and Monte Carlo (MC) RT. In the approximate RT, first proposed by Kylafis & Bahcall, only two terms of unscattered (direct) and single-scattered intensities are computed and higher-order multiple scattering components are approximated, saving computing time and cost compared to MC RT. However, the approximate RT can yield errors in regions where multiple scattering effect is significant. In order to examine how significant the errors of the approximate RT are, we compare results of the approximate RT with those of SKIRT, a state-of-the-art MC RT code, which is basically free from the approximation errors by fully incorporating all the multiple scattered intensities. In this study, we present quantitative errors in the approximate RT for late type galaxy models with various optical depths and inclination angles. We report that the approximate RT is not reliable if the central face-on optical depth is intermediate or high (${\tau}_V$ > 3).