• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.135-136
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• 2007

• The Journal of the Korea Contents Association
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• v.5 no.4
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• pp.103-110
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• 2005

In this paper, we present a shadow detection algorithm using the shadow features which appear in color images. Shadow regions have lower luminance and saturation than those of nearby regions, and is generally shown as dark colors. The regions are detected by means of analysing and applying their properties to images represented as the HSI color model. The proposed algorithm is consisted of two steps: at the first step, the candidate regions of shadow are found with using shadow features, and then, real shadow regions are detected only in candidate regions by using their information to reduce real objects and dark marks. The experimental results show that the algorithm is effective.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.773-776
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• 2000

Traffic monitoring plays an important role in intelligent transportation systems. It can be used to collect real-time traffic data concerning traffic flow. Passive shadows resulted from roadside buildings or trees and active shadows caused by moving vehicles, are one of the factors that arise errors in vision based vehicle detection. In this paper, a land mark based method is proposed for vehicle detection and shadow rejection, and finally vehicle count are achieved based on the land mark detection method.

• Journal of Astronomy and Space Sciences
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• v.40 no.4
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• pp.149-171
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• 2023

ShadowCam is a National Aeronautics and Space Administration Advanced Exploration Systems funded instrument hosted onboard the Korea Aerospace Research Institute (KARI) Korea Pathfinder Lunar Orbiter (KPLO) satellite. By collecting high-resolution images of permanently shadowed regions (PSRs), ShadowCam will provide critical information about the distribution and accessibility of water ice and other volatiles at spatial scales (1.7 m/pixel) required to mitigate risks and maximize the results of future exploration activities. The PSRs never see direct sunlight and are illuminated only by light reflected from nearby topographic highs. Since secondary illumination is very dim, ShadowCam was designed to be over 200 times more sensitive than previous imagers like the Lunar Reconnaissance Orbiter Camera Narrow Angle Camera (LROC NAC). ShadowCam images thus allow for unprecedented views into the shadows, but saturate while imaging sunlit terrain.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.403-411
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• 1999

The steel plate for shadow mask is used in a Cathode-ray tube of TV monitor and is the strictest product in surface quality because hundreds thousand of holes are perforated in a plane of 25 ${\times}$25 inches. To mass-produce this product, a reversible cold rolling mill for silicon steel was used and the rolling technology and the activity for quality improvement are described in this work. Because the steel plate is a mild steel, which is very sensitive to strip-breakage even in a low tension, we reset the minimum tension values matching to the operating conditions. The roll mark due to the multi-segmented araangement of shape controlling roll was prevented by hardening the intermediate shape controlling roll and by changing the existing working-roll into a HSS (Hig Speed Steel) roll. The scratch caused by the speed difference between a idle roll and a strip was prevented by increasing the roll roughness. With these activities, the steel plate for shadow mask can be stable. The continuous improvement of quality is, however, required for the customer satisfaction both of domestic and overseas market.

• Journal of Astronomy and Space Sciences
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• v.40 no.4
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• pp.131-148
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• 2023

Lunar permanently shadowed regions (PSRs) never see direct sunlight and are illuminated only by secondary illumination - light reflected from nearby topography. The ShadowCam imaging experiment onboard the Korea Pathfinder Lunar Orbiter is acquiring images of these PSRs. We characterize and discuss the nature of secondary illumination for the Shackleton PSR from ShadowCam radiance-calibrated images. We also use modeling to understand the magnitude and direction of the secondary illumination. Results from our analysis highlight the non-homogeneous, dynamic, and complex nature of PSR secondary lighting. Knowledge of the direction of the secondary illumination is crucial for reli-able interpretation of contrasts observed in ShadowCam images. This preliminary analysis of the floor of Shackleton crater from images acquired over multiple secondary illumination conditions does not reveal indications of exposed surface ice, even though temperatures are constantly below 110K.

• Journal of Astronomy and Space Sciences
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• v.40 no.4
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• pp.173-197
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• 2023

ShadowCam is a high-sensitivity, high-resolution imager provided by NASA for the Danuri (KPLO) lunar mission. ShadowCam calibration shows that it is well suited for its purpose, to image permanently shadowed regions (PSRs) that occur near the lunar poles. It is 205 times as sensitive as the Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC). The signal to noise ratio (SNR) is greater than 100 over a large part of the dynamic range, and the top of the dynamic range is high enough to accommodate most brighter PSR pixels. The optical performance is good enough to take full advantage of the 1.7 meter/pixel image scale, and calibrated images have uniform response. We describe some instrument artifacts that are amenable to future corrections, making it possible to improve performance further. Stray light control is very challenging for this mission. In many cases, ShadowCam can image shadowed areas with directly illuminated terrain in or near the field of view (FOV). We include thorough qualitative descriptions of circumstances under which lunar brightness levels far higher than the top of the dynamic range cause detector or stray light artifacts and the size and extent of the artifact signal under those circumstances.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.11
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• pp.610-620
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• 2003

Various shadows are one of main factors that cause errors in vision based vehicle detection. In this paper, two simple methods, land mark based method and BS & Edge method, are proposed for vehicle detection and shadow rejection. In the experiments, the accuracy of vehicle detection is higher than 96%, during which the shadows arisen from roadside buildings grew considerably. Based on these two methods, vehicle counting, tracking, classification, and speed estimation are achieved so that real-time traffic parameters concerning traffic flow can be extracted to describe the load of each lane.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.4 s.304
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• pp.21-30
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• 2005

In this paper, we propose lane detection and trackinB algerian using B-Snake as robust algorithm. One of chief virtues of Lane detection algorithm using B-Snake is that it is possible to specify a wider range of lane structure because B-Spline conform an arbitrary shape by control point set and that it doesn't use any camera parameter. Using a robust algorithm called CHVEP, we find the vanishing point, width of lane and mid-line of lane because of the perspective parallel line and then we can detect the both side of lane mark using B-snake. To demonstrate that this algorithm is robust against noise, shadow and illumination variations in road image, we tested this algorithm about various image divided by weather-fine, rainy and cloudy day. The percentage of correct lane detection is over 95$\%$.