• Korean Journal of Remote Sensing
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• v.35 no.2
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• pp.203-215
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• 2019

As hyperspectral sensors that can be mounted on drones are developed, it is possible to acquire hyperspectral imagery with high spatial and spectral resolution. Although the importance of atmospheric correction has been reduced since imagery of drones were acquired at a low altitude,studies on the conversion process from raw data to spectral reflectance should be done for studies such as estimating the concentration of surface materials using hyperspectral imagery. In this study, a vicarious radiometric calibration and an atmospheric correction algorithm based on atmospheric radiation transfer model were applied to hyperspectral data of drone and the results were compared and analyzed. The vicarious calibration method was applied to an empirical line calibration using the spectral reflectance of a tarp made of uniform material. The atmospheric correction algorithm used ATCOR-4 based Modran-5 that was widely used for the atmospheric correction of aerial hyperspectral imagery. As a result of analyzing the RMSE of the difference between the reference reflectance and the correction, the vicarious calibration using the tarp in a single period of hyperspectral image was the most accurate, but the atmospheric correction was possible according to the application purpose of using hyperspectral imagery. If the correction process of normalized spectral reflectance is carried out through the additional vicarious calibration for imagery from multiple periods in the future, accurate analysis using hyperspectral drone imagery will be possible.

• Korea Multimedia Society
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• v.7 no.2
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• pp.32-43
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• 2003

• Korean Journal of Optics and Photonics
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• v.21 no.2
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• pp.46-52
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• 2010

A theory of bidirectional reflectance-distribution function (BRDF), a newly developed BRDF measurement system, and a method for evaluating the uncertainty of BRDF measurements are presented. The BRDF measurement system which measures BRDF in a wavelength range of (380~1500) nm with an angle range of $(-75{\sim}75)^{\circ}$ was installed. The measurement uncertainties, consisting of correlated terms and uncorrelated terms, were evaluated for the BRDF measurement system, resulting in the relative expanded uncertainty less than 3% (k=2).

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2004.11a
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• pp.117-117
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• 2004

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.216-217
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• 2000

상자성을 갖는 분자에 대한 분광학 연구에서는 제만(Zeeman) 효과로 생기는 이색성을 이용한 magnetic rotation spectroscopy (MRS)가 널리 사용되고 있다.$^{(1)}$ MRS가 일반적인 흡수 분광법에 비해 더 민감한 측정을 할 수 있기는 하지만 사용하는 편광기의 extinction ratio에 의해 감도가 한정된다. MRS의 감도를 높이는 방법으로는 광경로를 길게 만드는 것을 고려할 수 있다. 일반적으로 공진기 광자감쇠 분광학(Cavity Ring-Down Spectroscopy, CRDS)은$^{(2)}$ 높은 반사율을 갖는 거울을 사용해서 수 km 이상의 광 경로를 만들기 때문에 감도가 높다. (중략)

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.262-265
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• 2021

The purpose of this development is to prevent accidents in the telephone poles caused by bird nests in advance. It is a sensor node installed on a telephone pole to recognize a bird's nest. This is to remove the bird before it builds a nest and lays eggs. It is in the system that recognizes the bird nest by the change of the distance when the sensor is first installed and the distance value measured thereafter. In this paper, we have designed and tested infrared rays with concrete, iron plate, wood, and plastic bag are targeted. This is an object that can be detected within a telephone pole was tested. The value of the spectrum detected by the spectral reflectance was obtained through a photodiode. Through the standard deviation graph of these values, it became possible to predict the target of the object and measure the distance. As a result of this experiment, target information (concrete, iron plate, wood, plastic bag) about dangerous substances in the telephone pole was acquired through the infrared sensor. Through this, it is expected that it will contribute to the establishment of a safe power grid and a coexistence environment with nature through power grid monitoring.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.317-327
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• 2013

Air pollution and artificial heat of urban areas have caused the urban heat island in which asphalt pavements absorb solar heat during the daytime and release the heat at night. Hence, in order to improve the environment of urban areas, it is necessary to examine cooling pavements that can reduce heat on road pavements in urban areas. The application of temperature insulation paints on road pavements require to reduce black brightness for visibility, to increase the reflection rate of infrared light and minimize the reflection rate of visible light. In the study, one part of Acrylic-emulsion was used as a main binder, and the changes in black brightness and the changes of addition ratio (0%, 15%, 30%) of hollow ceramics, as well as kinds of paints (carbon black pigment, mixed mineral pigment) were selected as the main experimental factors. The performance of temperature reduction of cooling pavements was analyzed through the reflection rate of spectrum, the reflection rate of solar heat, and the lamp test. Abrasion resistance, UV accelerated weather resistance, and sliding resistance were tested in real situations. In addition, the performance of heat reduction of testing pavements covered with high-reflection paints was analyzed by using an infrared camera. As the test results, when using mixed mineral paints and hollow ceramic of 30%, the reflection rate of spectrum was 43% in the area of near-infrared ray and 17% in the area of visible light at black brightness of $L^*$=42.89 and the reflection rate of solar heat was 27.5%. Total color difference was ${\Delta}E$=0.27 in the test of UV Accelerated Weather Resistance, indicating almost no changes in color. BPN was more than 53 when scattering #2 and #4 silica sand of more than $0.12kg/m^2$. In Taber's abrasion resistance test, abrasion loss was up to 86.4mg at 500 rotations. The performance of heat reduction was evaluated using an infrared camera at the test section applying high-reflection paints to asphalt pavements, in which the results showed that the temperature was reduced by $12.7^{\circ}C$ on CI-30-40 cooling pavements ($L^*$=38.76) and by $14.2^{\circ}C$ on CI-30-60 cooling pavements ($L^*$=57.12).

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.204-205
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• 2003

미량기체의 흡수스펙트럼을 높은 감도로 측정하는 공동 광자감쇠 분광법(cavity ringdown spectroscopy； CRDS)을 나노초 레이저 펄스의 차주파수 생성(difference-frequency generation； DFG)을 광원으로 이용하여 파장 3 ~ 4 $\mu\textrm{m}$ 영역에서 구현하였다. CRDS는 고반사율 거울로 이루어진 광학적 공동에 단일 파장의 빛을 가두었다가 그 에너지의 시간적 감소율을 측정하여 공동 속 기체의 흡수율을 알아내는 방법이다. (중략)

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.325-330
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• 2004

We fabricated a vacuum ultraviolet spectre-reflectometer which consists of a deuterium light source, a vacuum monochromator, and a sample chamber and detector module. The operation was performed in the ultraviolet spectral ranges between 115 nm and 330 nm at the vacuum pressure of 3.0 ${\times}$ 10$^{-4}$ Pa. The wavelength of the vacuum monochromator was calibrated with the line spectrum of a low pressure Mercury lamp of 253.652 nm and 184.95 nm wavelengths, and its resolution was 0.012 nm, and the precision of wavelength was $\pm$ 0.03 nm. With this reflectometer and a deuterium lamp, we measured the spectral regular transmittance and reflectance of materials(MgF$_2$, CaF$_2$, BaF$_2$, SiO$_2$, Sapphire) used as optical components over the spectral range between 115 nm and 230 nm.

• Journal of the Korean Vacuum Society
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• v.17 no.2
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• pp.138-147
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• 2008

$SiO_2/TiO_2/ZrO_2$ broadband anti-reflective multi-layer thin films were prepared at room temperature by RF sputtering system. Optical constants and structural properties on each layer of films were analyzed by spectroscopic ellipsometer and transmittance spectra of the films were measured by $UV-V_{is}$ spectrophotometer in the range of 300$\sim$900 nm. To evaluate the films, we compared the measured and analyzed spectra with designed spectra. We investigated influence of discrepancy of thickness and refractive indices of each layer on changes of the transmittance spectra. It was found that refractive indices and shape of dispersion of deposition materials are more contributed to changes of the transmittance spectra than thickness of layer.