• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.10
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• pp.93-97
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• 2005

We have developed the FDSS (Fine Digital Sun Sensor) for the space technology of the STSAT-2 (Seience & Technology Satellite 2). The FDSS is firstly developed by using CMOS image sensor(CIS) in South Korea. The FDSS consists of the optics part, FPGA(Field Programable Gate Array) part, and MCU(Micro controller unit)part. This paper will focus on the optical characteristics of the optics part and describe the configuration of FDSS with the design of aperture. We also analyze the characteristic of optics about the pixel of the CMOS image sensor.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.5
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• pp.460-465
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• 2007

This paper deals with the Fine Digital Sun Sensor (FDSS) for Science & Technology Satellite 2(STSAT-2). The FDSS was firstly developed by using CMOS-Image sensor(CIS) in South Korea. This paper will describe the configuration of the FDSS, the design of the optical part, the analysis result of the optical characteristics of the sunlight, and the calibration result measured by solar simulator.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.11
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• pp.1043-1051
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• 2007

The digital sun sensor calculates the incident sunlight angle using the sunlight image registered on a CMOS image sensor. In order to accomplish this, an exact center of the sunlight image has to be determined. Therefore, an accurate estimate of the centroid is the most important factor in digital sun sensor development. The most general method for determining the centroid is the thresholding method, and this method is also the simplest and easy to implement. Another centering algorithm often used is the image filtering method that utilizes image processing. The sun sensor accuracy using these methods, however, is quite susceptible to noise in the detected sunlight intensity. This is especially true in the thresholding method where the accuracy changes according to the threshold level. In this paper, a template method that uses the sunlight image model to determine the centroid of the sunlight image is suggested, and the performance has been compared and analyzed. The template method suggested, unlike the thresholding and image filtering method, has comparatively higher accuracy. In addition, it has the advantage of having consistent level of accuracy regardless of the noise level, which results in a higher reliability.

• Applied Chemistry for Engineering
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• v.34 no.3
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• pp.207-212
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• 2023

Near-infrared (NIR) absorbing dyes have been applied to various applications such as optical filters, biotechnology, energy storage and conversion, coating additive, and traditionally information-storage materials. Because image sensors used in cellphones and digital cameras have sensitivity in the NIR region, the NIR cut-off filter is essential to achieving more clear images. As energy storage and conversion have been important, diverse NIR absorbing materials have been developed to extend the absorption region to the NIR region, and NIR absorbing materials-based research has proceeded to improve device performances. Adding NIR-absorbing dye with a photo-thermal effect to a self-healable coating system has been attractive for future mobility technology, and more effective self-healing properties have been reported. In this report, the chemical structures of representative NIR-absorbing dyes and state of the art research based on NIR-absorbing dyes are introduced.

• Korean Journal of Remote Sensing
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• v.29 no.5
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• pp.555-568
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• 2013

Atmospheric optical thickness during nighttime was estimated in this study using analysis on the images of the moon taken from commercial digital camera. Basically the Langely Regression method was applied to the observations of the moon for the cloudless and optically stable sky conditions. The spectral response functions for the red(R), green(G), and blue(B) channels were employed to derive effective wavelength centers of each channel for the observations of the moon, and the correspondent Rayleigh optical thickness were also calculated. Aerosol optical thickness (AOT) was calculated by subtracting Rayleigh optical thickness from the atmospheric optical thickness derived from the Langley regression method. As there are only handful of nighttime AOT observations, the AOT from the moon observations was compared with the AOT from sun-photometers and the MODIS satellite sensor, which was taken several hours before the moon observations of this study. As a result, the values of AOT from moon observations agree with those from sun-photometers and MODIS within 0.1 for the R, G, B channels of the digital camera. On the other hand, ${\AA}$ngstr$\ddot{o}$m Exponent seems to be subject to larger errors due to its sensitiveness to the spectral errors of AOT. Nevertheless, the results of this study indicate that the method reported in this study is promising as it can provide nighttime AOT relatively easily with a low cost instrument like digital camera. More observations and analyses are warranted to attain improved nighttime AOT observations in the future.