• Journal of Biosystems Engineering
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• v.38 no.3
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• pp.199-207
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• 2013

Purpose: Tomatoes, an important agricultural product in fresh-cut markets, are sometimes a source of foodborne illness, mainly Salmonella spp. Growth cracks on tomatoes can be a pathway for bacteria, so its detection prior to consumption is important for public health. In this study, multispectral Visible/Near-Infrared (NIR) reflectance imaging techniques were used to determine optimal wavebands for the classification of defect tomatoes. Methods: Hyperspectral reflectance images were collected from samples of naturally cracked tomatoes. To classify the resulting images, the selected wavelength bands were subjected to two-band permutations, and a supervised classification method was used. Results: The results showed that two optimal wavelengths, 713.8 nm and 718.6 nm, could be used to identify cracked spots on tomato surfaces with a correct classification rate of 91.1%. The result indicates that multispectral reflectance imaging with optimized wavebands from hyperspectral images is an effective technique for the classification of defective tomatoes. Conclusions: Although it can be susceptible to specular interference, the multispectral reflectance imaging is an appropriate method for commercial applications because it is faster and much less expensive than Near-Infrared or fluorescence imaging techniques.

• Journal of Surface Science and Engineering
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• v.40 no.3
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• pp.138-143
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• 2007

The effects of texturing and anti-reflection coating on the reflection properties of multi-crystalline silicon solar cell have been investigated. The chemical solutions of alkaline and acidic etching solutions were used for texturing at the surface of multi-crystalline Si wafer. Experiments were performed with various temperature and time conditions in order to determine the optimized etching condition. Alkaline etching solution was found inadequate to the texturing of multi-crystalline Si due to its high reflectance of about 25%. The reflectance of Si wafer texturing with acidic etching solution showed a very low reflectance about 10%, which was attributed to the formation of homogeneous. Also, deposition of ITO anti-reflection coating reduced the reflectance of multi-crystalline si etched with acidic solution($HF+HNO_3$) to 2.6%.

• Proceedings of the KSRS Conference
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• 2009.03a
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• pp.254-259
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• 2009

In this study, Simplified Method for the Atmospheric Correction (SMAC) radiative transfer model (RTM) used to retrieve surface reflectance from MODIS Top Of Atmosphere (TOA) reflectance (MOD02). SMAC code provides coefficients which were previously yielded by Second Simulation of the Satellite Signal in the Solar Spectrum (6S) for each satellite sensor. We conducted error analysis of SMAC RTM using MOD02 over comparison with MODIS surface reflectance (MOD09) which was provided from 6S. It showed that low accuracy values such as, $R^2$ : 0.6196, Root Means Square Error (RMSE) : 0.00031, bias : - 0.0859. Thus sensitivity analysis of input parameters and coefficients was conducted to searching error sources. Coefficients about $\tau_p$ (average AOD) are more influence than any other coefficients of $\tau_{a550}$ (Aerosol Optical Depth at 550nm) from sensitivity test. Calibrated coefficients of $\tau_p$ from regression analysis were used to surface reflectance which showed that improve accuracy of surface reflectance ($R^2$ : 0.827, RMSE : 0.00672, bias : - 0.000762).

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.8
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• pp.2749-2763
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• 2021

The desirable result of infrared (IR) and visible (VIS) image fusion should have textural details from VIS images and salient targets from IR images. However, detail information in the dark regions of VIS image has low contrast and blurry edges, resulting in performance degradation in image fusion. To resolve the troubles of fuzzy details in dark regions of VIS image fusion, we have proposed a method of reflectance estimation for IR and VIS image fusion. In order to maintain and enhance details in these dark regions, dark region approximation (DRA) is proposed to optimize the Retinex model. With the improved Retinex model based on DRA, quasi-Newton method is adopted to estimate the reflectance of a VIS image. The final fusion outcome is obtained by fusing the DRA-based reflectance of VIS image with IR image. Our method could simultaneously retain the low visibility details in VIS images and the high contrast targets in IR images. Experiment statistic shows that compared to some advanced approaches, the proposed method has superiority on detail preservation and visual quality.

• Korean Journal of Optics and Photonics
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• v.32 no.3
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• pp.114-119
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• 2021

A large-area graphene sheet has been successfully grown on a copper-foil substrate by chemical vapor deposition (CVD) for industrial use. To screen out unsatisfactory graphene films as quickly as possible, noninvasive optical characterization in reflection geometry is necessary. Based on the optical conductivity of graphene, developed by the single-electron tight-binding method, we have investigated the optical-reflectance contrast. Depending on the four independent control parameters of layer number, chemical potential, hopping energy, and temperature, the optical-reflectance contrast can change dramatically enough to reveal the quality of the grown graphene sheet.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.95-99
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• 1999

We proposed a new retrieval method for aerosol's real part of refractive index, optical thickness, and Angstrom exponent using POLDER's directional reflectance and polarization data. We showed that aerosol's real part of refractive index can be retrieved systematically using multi-directional PR(polarization and reflectance) diagrams in a single infrared band by our algorithm for the first time. We examined the retrieved results, by comparing with the simultaneously measured sky observation data at the study site and we obtained a reasonable agreement between them.

• Journal of Biosystems Engineering
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• v.19 no.1
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• pp.33-41
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• 1994

In order to evaluate the quality of peaches non-destructively, the surface color and spectral reflectances of KURAKATAWASE, MIBAEKTO, and OKUBO cultivar were measured. Also an attempt was made to correlate reflectance characteristics and tristimulus values with quality evaluation parameters such as chlorophyll content, soluble solids, anthocyanin content, and firmness. Further analysis of the correlation coefficients showed that spectral reflectance would be effective for the quality evaluation of peaches.

• KCID journal
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• v.10 no.2
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• pp.43-54
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• 2003

This study investigated the spectral reflectance and leaf area index (LAI) of field crops and determined vegetation indices when intermixed with field crops and soil. Ground-level spectral reflectance and leaf area index (LAJ) were collected for eight cro

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1580-1582
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• 2007

The composites were fabricated with titania used commercially and calcite as a filler in BZB glass matrix and their thermal, optical and electrical properties were investigated. From our results, calcite may be the profitable and highly efficient reflectance material as a filler for flat panel display devices.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.292-294
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• 2008

We have developed new reflective LCD for Mixed twist nematic LC mode with high quality image. We have found out an optimal twist angle of LC and optical film's axis by simulation. Also we measured electro-optic characteristics for new design panel. As a result, high reflectance and wide viewing angle characteristics were achieved.