• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.299-299
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• 2010

태양전지 셀에서 표면 반사에 의한 태양광 손실을 보다 적게 하여 흡수량 증가시킬 필요가 있다. 태양전지에서 생성된 전자 정공 수집 향상을 위해 금속 재질로 이루어진 그리드 전극을 사용한다. 이때 금속 그리드에 입사되는 태양광은 대부분 반사되어 입사광의 손실로 이어진다. 본 연구에서는 결정질 실리콘 태양전지에서 표면 그리드에 의한 광학적 손실을 반사율을 통해 확인하였고 양자효율을 측정하여 보았다. 결정질 실리콘 태양전지 표면 반사율 측정은 적분구를 사용하였고, 측정에 사용된 태양전지 샘플은 일반적인 구조의 결정질 실리콘 태양전지이다. 실험은 표면 그리드 공정 전 후의 샘플로 실험을 진행하였고, 셀의 표면 균일도에 의한 확인을 위하여 동일한 면적 비율의 입사광을 조사하여 반복 실험을 하였다. 양자효율 측정은 광학 초퍼를 통한 광원과 분광기 및 검출기를 포함하는 태양전지 특성 분석 장치를 사용하였다. 그 결과 특정 파장 대역에서 그리드의 유무에 따른 반사율의 변화와 이에 따른 양자효율의 변화를 통하여 그리드에 의한 결정질 실리콘 태양전지의 특성변화에 대해 알아보았다.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.2
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• pp.151-155
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• 2000

We calculated a refractive index of the lens surface by measuring a spectral reflectance for a tinted time on manufacturing of the color lens. The longer a tinted time, the larger a reflectance and reflective index. The refractive index increased for a time up to the colorant's saturation state on the lens surface. The refractive index's change curve of blue color lens for a time depended on the Boltzmann growth curve. then we obtained the parameter's values of $n_{min}=1.482$, $n_{max}=1.497$, $t_c=11.53$ and $d_0=2.287$.

• The Journal of Engineering Geology
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• v.32 no.1
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• pp.101-111
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• 2022

This study analyzed the relationship between water turbidity and its reflectance, as measured using hyperspectral imaging. First, samples of turbid water were generated in boxes. This was followed by drone-based hyperspectral imaging and analysis of the correlation between the samples' measured turbidity and hyperspectral reflectance. The nine boxes for turbidity measurement were made of black acrylic that absorbed all light turbidity was induced using soil collected near Changhacheon, which causes turbidity in Imha Lake. The results indicate that the reflectance of wavelengths in the near-infrared region followed a pattern of increase with increasing soil content for each box. Analysis of this correlation between the turbidity and average reflectance measured in each box yielded a very high R² value of 0.8702, indicating that reflectance is a suitable proxy for turbidity.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.6
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• pp.630-639
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• 2001

This study proposes a new calculation method for generating real nighttime lamp-lit images. In order to improve the color appearance in the prediction of a nighttime lamp-lighted scene, the lamp-lit image is synthesized based on spectral distribution using the estimated local spectral distribution of the headlamps and the surface reflectance of every object. The Principal component analysis method is introduced to estimate the surface color of an object, and the local spectral distribution of the headlamps is calculated based on the illuminance data and spectral distribution of the illuminating headlamps. HID and halogen lamps are utilized to create beam patterns and captured road scenes are used as background images to simulate actual headlamp-lit images on a monitor. As a result, the reproduced images presented a color appearance that was very close to a real nighttime road image illuminated by single and multiple headlamps compared to the conventional graphic-based algorithm.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.2
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• pp.70-78
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• 2009

Remote sensing technique in agriculture can be used to identify chlorophyll content, biomass, and yield caused from N stress level. This study was conducted to evaluate biomass, N stress levels, and yield of tobacco (Nicotiana tabacum L.) under sand culture in a plastic film house using ground-based remote sensors. Nitrogen rates applied were 40, 60, 80, 100, 120, and 140 percent of N concentration in the Hoagland's nutrient solution. Sensor readings for reflectance indices were taken at 30, 35, 40, 45, 50 and 60 days after transplanting(DAT). Reflectance indices measured at 40th DAT were highly correlated with dry weight(DW) of tobacco leaves and N uptake by leaves. Especially, green normalized difference vegetation index(gNDVI) from spectroradiometer and aNDVI from Crop Circle passive sensor were able to explain 85% and 84% of DW variability and 85% and 92% of N uptake variability, respectively. All the reflectance indices measured at each sampling date during the growing season were significantly correlated with tobacco yield. Especially the gNDVI derived from spectroradiometer readings at the 40th DAT explained 72% of yield variability. N rates of tobacco were distinguished by sufficiency index calculated using the ratio of reflectance indices of stress to optimum plot of N treatment. Consequently results indicate that the reflectance indices by ground-based remote sensor can be used to predict tobacco yield and recommend the optimum application rate of N fertilizer for top dressing of tobacco.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.546-549
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• 2010

RGB 영상의 색 재현성과 조건등색 등의 한계를 개선하기 위해 다중스펙트럼 영상을 활용하는 연구가 활발히 진행되고 있다. 다중스펙트럼 영상을 측정하기 위해서 흑백카메라와 3 개 이상의 컬러 필터들을 이용한다. 본 연구에서는 LCTF 를 사용하여 400nm 에서 720nm 까지 10nm 단위로 33 개의 필터를 사용한다. 이러한 다중스펙트럼 영상 측정 시스템의 특성화를 수행하기 위해 컬러체커뿐만 아니라 광원정보까지 이용하며, 사물의 스펙트럼 반사율도 추정한다. 따라서 분광방사계 보다 빠르게 영상 기반으로 스펙트럼 반사율을 측정할 수 있다. 다양한 광원 조건에서 특성화를 수행하며, 매번 레퍼런스 차트를 측정할 필요 없이 간단히 광원만 측정해도 되는 것을 보인다. 또한 전경영상에서 원하는 영역을 광원환경이 다른 배경 영상에 합성할 때, 자연스러운 사물의 색 변환이 가능하여 보다 실제에 가까운 합성 영상을 생성한다.

• Journal of the Korean Geosynthetics Society
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• v.21 no.4
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• pp.93-100
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• 2022

This study describes the evaluation results on the effect of soil particle surfaces coated with various hydrophobic conditions on spectral information according to water content. Wettability test and spectral information evaluation test were performed on the hydrophobic coated standard sand. When the standard sand was coated with 1%, 3%, and 5% hydrophobic, the contact angles of sand-water interface were 130°~143°, 129°~144°, and 131°~144°, respectively. This means that the contact angle increased as the degree of hydrophobic coating increased at the same drying time, but the range of the contact angle had the same wettability. This means that the contact angle increases as the hydrophobic coating degree increases at the same drying time, whereas the contact angle range has the same wettability. As a result of spectral information evaluation, the maximum spectral reflectance of the dried sand with hydrophobic condition decreased compared to that of the hydrophilic sand, as the degree of hydrophobic increased. However, the maximum spectral reflectance was increased by increasing the degree of hydrophobic under the same water content conditions.

• Journal of the Institute of Convergence Signal Processing
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• v.2 no.2
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• pp.39-46
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• 2001

In this paper we propose a new method that can be estimation the spectral power distribution of the light source from three-band images. the light source is estimated by dividing the reflected spectral power distribution of the maximum achromatic region(L(λ)) by the corresponding surface reflectance(Ο(λ)). In order to obtain reflected spectral power distribution of the maximum achromatic region from three-bend images, a modified gray world assumption algorithm is adapted. And the maximum surface reflectance is estimated using the principal component analysis method along with achromatic population. The achromatic population is created from a set of given Munsell color chips whose chroma vector is less than threshold. Cumulative contribution ratio of principal components from the first to the third for classified achromatic population was about 99.75%. The reconstruction of illumination spectral power distribution by using achromatic population and three-band digital images captured under various light source was examined, and evaluated by RMSE between the original and reconstructed illumination spectral power distribution. This work was supported by grant No (2000-1-30200-005-3) from the Basic Research Program of the Korea Science & Engineering Foundation.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.4
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• pp.393-399
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• 2005

Since vegetations are near the wavelength range in 700nm and have absorbent as well as reflective wavelength ranges, there is a much difference in terms of its reflection rate. There are currently many researches on vegetation index being conducted in order to apply the remote-sensing technology to vegetations rising their characteristics of absorbent and reflective wavelength ranges. Normalized Difference Vegetation Index (NDVI) and Perpendicular Vegetation Index (PVI) have been most commonly used. It is usually the evaporation, carbon-dioxide consumption, and chlorophyll density that represent the activity of vegetation, but chlorophyll density is the most commonly used among them. Since the red wavelength range used to obtain the NDVI and PVI has a strong extinction of chlorophyll, it is also useful to test chlorophyll density. The NDVI, in particular, is used to identify the vegetation conditions summarily, and thus, is suitable for initiative researches. Nevertheless, since these vegetation index produce mixed information of the Vegetation vigor and vegetation cover, it is essential to monitor a wavelength range that is independent from redundancy of the Vegetation vigor and vegetation cover. Although many vegetation indices have evaluated both the vegetation vigor and Vegetation cover simultaneously, this research intends to emphasize the utility of separable evaluations of the Vegetation vigor and Vegetation Cover rate through an experiment with grasses. As a result of evaluating vegetation index using spectral reflectance, a separable evaluation of the vegetation vigor and cover has been found more useful.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.48-48
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• 2020

최근 이상기후변화로 인해 수환경 변화가 일어나고 있다. 그로 인해 국내에서 조류의 과대성장이 빈번히 발생되고 있으다. 이로 인해 유해남조류 등 조류가 생산하는 독성물질, 이취미 물질은 수질을 악화시키고 있으며, 생태계에 큰영향을 미친다. 조류는 하천에서 넓은 분포로 발생하게 되는데 이러한 조류 모니터링에는 많은 인력과 시간이 소요된다. 국내에선 인력과 시간을 줄이기 위해 최근 원격탐사 기법을 이용한 조류 모니터링에 대한 연구가 많이 진행되고 있다. 본 연구에서는 녹조류, 남조류 5종을 이용해 실험을 진행하였다. 사용된 초분광 센서는 CORNING사의 microHSI^TM 410 SHARK를 이용하였으며 파장 400-1000 nm에서 NIR(visNIR)파장을 분석할 수 있으며, 초분광 센서를 정사로 영상을 촬영하기 위해 짐벌을 이용하여 영상을 수집하였다. 영상을 촬영 전 방사보정을 하기 위해 시료와 동일 선상에 99% 반사율을 갖는 백색반사판을 같이 촬영하여 방사보정을 진행하였다. 본 연구에서는 시기와 상관없이 조류에 대한 연구를 하기위해 조류배양액을 이용하였으며, 남조의 경우 470 nm에서 분광 특성을 나타내었으며, 녹조의 경우 477-510 nm에서 분광 특성을 나타났다. 초분광영상을 통해 기초라이브러리를 구축하고 구축된 라이브러리를 통해 조류의 분광특성을 분석하고 제시하여 하천에 적용하고자 한다.