• IEMEK Journal of Embedded Systems and Applications
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• v.8 no.2
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• pp.111-119
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• 2013

This paper proposes one method on photometric stereo calibration using the constraint on light source directions in which the light sources have the unknown tilt and slant angles but the slant angles are the same. First, the constraint is analyzed based on the equation of linear ambiguity which leads to the conclusion that another constraint should be added to solve the calibration completely. Later, the combination of constraint on light source directions and the constraint that there exists at least six surface patches having known albedos is exploited to resolve the linear ambiguity up to an accurate and close-form solution. The effective performance of the proposed method is demonstrated through experiment results.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.243-247
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• 2009

A Radioactive constraint of the nuclear fuel assembly irradiated by neutron during normal operation cycle of the nuclear power plant is typically on the order of about 3 kGy/h. In order to inspect nuclear fuel assembly using a VT (vision technology) system, the light such as halogen lamp is used. As the halogen lamp has lower color temperature than the sun light, the objects under halogen lamp illumination are seemed to be tinted with red. In this paper, high brightness LED is considered to be used as the light source of VT system. The high brightness LED, which is a key light source of the VT system, have been gamma irradiated at the dose rate of 4 kGy/h during two hours up to a total dose of 8 kGy. The radiation induced color-center in the LED housing cap made of plastics materials is observed.

• Analytical Science and Technology
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• v.31 no.5
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• pp.195-200
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• 2018

Researchers have used the visual criteria to compare the effectiveness of fingerprint enhancement techniques. However, since the visual criteria is subjective, bias can occur. Therefore, many researchers have tried to make the criteria objective using the contrast index (CI). However, there is a constraint that the CI was only validated on inked fingerprints or color-change fingerprints. In this study, we compared enhancement of fluorescence fingerprints on colored papers using the CI. The CI values differ according to the color of the background, reagent, and light source, even though the same standard fingerprints were used. Through the comparison of values, we could compare the enhancement of fluorescence fingerprints according to these factors. When visual evaluation criteria were used, the same peak score was obtained regardless of the reagent and light source. However, we could get a more detailed score comparison in this study using the CI. Therefore, it is confirmed that for comparison of enhancement of fluorescence fingerprints, the CI can be used as a basis for determining which light source and reagent are appropriate according to the background.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.6
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• pp.710-717
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• 2015

Projection stereolithography is an additive manufacturing method that uses beam projection to cure the photo-reactive resin used. The light source of a cross-section layer-form illuminates photo-curable resin for building a three-dimensional (3D) model. This method has high accuracy and a fast molding speed because the processing unit is a face instead of a dot. This study describes a Scalable Projection Stereolithography 3D Printing System for improving the accuracy of the stereolithography. In a conventional projection 3D printer, when printing a small sized model, many pixels are not used in the projection or curing. The proposed system solves this problem through an optical adjustment, and keeps using the original image as possible as filling the whole projection area. The experimental verification shows that the proposed system can maintain the highest level of precision regardless of the output size.