• Korean Journal of Optics and Photonics
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• v.20 no.2
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• pp.134-140
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• 2009

In this study, the influence of surface roughness on light scattering from Au pads on a PCB surface was investigated. Angular distributions of light scattered from Au pads with different surface roughness were measured for several incident angles. Diffusely-scattered light could be separated by using the fact that the amount of specularly-scattered light was directly related to surface roughness. The separated diffuse term was curve-fitted with a physics-based model, and then the related scattering parameters were extracted and compared with measured parameters.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.211.1-211.1
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• 2012

The on-orbit test simulation for predicting the instrument directional responsivity was conducted by the Monte Carlo based integrated ray tracing (IRT) computation technique and analytic flux-to-signal conversion algorithms. For the on-orbit test simulation, the Sun model consists of the Lambertian scattering sphere and emitting spheroid rays, the Amon-Ra instrument is a two-channel including a broadband scanning radiometer (energy channel) and an imager with ${\pm}2^{\circ}$ FOV (visible channel). The solar radiation produced by the Sun model is directed to the instrument viewing port and traced through the dual channel optical train. The instrument model is rotated on its rotation axis and this gives a slow scan of the Sun model over the full field of view. The direction of the incident lights are fed with scanned images obtained from the visible channel instrument. The instrument responsivity was computed by the ratio of the incident radiation input to the instrument output. In the radiometric simulation, especially, measured BRDF of the 3D CPC was used for scattering effects on radiometry. With diamond turned 3D CPC inner surface, the anisotropic surface scattering model from the measured data was applied to ray tracing computation. The technical details of the on-orbit test simulation are presented together with field-of-view calibration plan.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.6 s.312
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• pp.46-56
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• 2006

In this paper, we propose an improved reproduction algorithm for a realistic image of the real scene based on the optical characteristics of the light sources and the materials at the lighting environment. This paper is continuation of the previous study to improve the modeling method of the light sources and the materials and apply this to the real rear lamp of automobile. The backward ray tracing method is first used to trace the light ray from a light source, and also considers the physical characteristics of object surfaces and geometric properties of light radiation to estimate accurately the light energy incoming toward to human eyes. For experiments and verification of the proposed method, the simulation results are compared with the measured light stimuli. Accordingly, the simulation results show that the proposed algorithm can estimate light energy well and reproduce the visually similar image with a scene incident on a sight of viewer.

• Korean Journal of Remote Sensing
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• v.38 no.1
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• pp.83-101
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• 2022

Accurate atmospheric correction is essential for the analysis of land surface and environmental monitoring. Aerosol optical depth (AOD) information is particularly important in atmospheric correction because the radiation attenuation by Mie scattering makes the differences between the radiation calculated at the satellite sensor and the radiation measured at the land surface. Thus, it is necessary to use high-quality AOD data for an appropriate atmospheric correction of high-resolution satellite images. In this study, we examined the Second Simulation of a Satellite Signal in the Solar Spectrum (6S)-based atmospheric correction results for the Sentinel-2 images in South Korea using raster AOD (MODIS) and single-point AOD (AERONET). The 6S result was overall agreed with the Sentinel-2 level 2 data. Moreover, using raster AOD showed better performance than using single-point AOD. The atmospheric correction using the single-point AOD yielded some inappropriate values for forest and water pixels, where as the atmospheric correction using raster AOD produced stable and natural patterns in accordance with the land cover map. Also, the Sentinel-2 normalized difference vegetation index (NDVI) after the 6S correction had similar patterns to the up scaled drone NDVI, although Sentinel-2 NDVI had relatively low values. Also, the spatial distribution of both images seemed very similar for growing and harvest seasons. Future work will be necessary to make efforts for the gap-filling of AOD data and an accurate bi-directional reflectance distribution function (BRDF) model for high-resolution atmospheric correction. These methods can help improve the land surface monitoring using the future Compact Advanced Satellite 500 in South Korea.