• Journal of Korea Water Resources Association
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• v.55 no.4
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• pp.301-308
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• 2022

Algae is an indispensable primary producer in the ecosystem by supplying energy to consumers in the aquatic ecosystem, and is largely divided into green algae, blue-green algae, and diatoms. In the case of blue-green algae, the water temperature rises, which occurs in the summer and overgrows, which is the main cause of the algae bloom. Recently, the change in the occurrence time and frequency of the algae bloom is increasing due to climate change. Existing algae survey methods are performed by collecting water and measuring through sensors, and time, cost and manpower are limited. In order to overcome the limitations of these existing monitoring methods, research has been conducted to perform remote monitoring using spectroscopic devices such as multispectral and hyperspectral using satellite image, UAV, etc. In this study, we tried to confirm the possibility of species classification of remote monitoring through laboratory-scale experiments through algal culture and river water collection. In order to acquire hyperspectral images, a hyperspectral sensor capable of analyzing at 400-1000 nm was used. In order to extract the spectral characteristics of the collected river water for classification of algae species, filtration was performed using a GF/C filter to prepare a sample and images were collected. Radiation correction and base removal of the collected images were performed, and spectral information for each sample was extracted and analyzed through the process of extracting spectral information of algae to identify and compare and analyze the spectral characteristics of algae, and remote sensing based on hyperspectral images in rivers and lakes. We tried to review the applicability of monitoring.

• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.185-186
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• 2009

• Proceedings of the Optical Society of Korea Conference
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• 2006.02a
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• pp.285-286
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• 2006

• Journal of Korean Society of Environmental Engineers
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• v.35 no.6
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• pp.442-448
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• 2013

There are two approaches in measuring colors (or chromaticity) in water, i.e., visual comparison method and spectrophotometric method. The color of sample was determined by comparing with that of platinum-cobalt standard solution in the visual comparison method. Single or multiple wavelengths are used for the spectrophotometric method. As the accuracy and precision of visual comparison method depend on the eye sight of the analyzer, the results are not so reliable and representative. In addition, it is hard to measure chromaticity less than 5 TCU. Single wavelength approach in spectrophotometric method, can be applied for groundwater or surface water with natural organic matter (i.e., humic substances) while it's hard to measure the color of wastewater which includes anthropogenic chemical compounds. The measurements with multiple wavelengths approach resulted in reliable data regardless of the source of sample water, i.e., surface water and wastewater. As dozens of measurements and complicated calculations for one sample were required for the multiple wavelengths approach, the approach could not be applied for field measurement. In the present study, the authors tested efficient method which could measure the color of water sample accurately and precisely regardless of the source of water. With the colorimeter with multiple wavelengths and calculation program, the colors of water samples could be measured within 3~4 seconds with accuracy and precision.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.6
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• pp.1009-1017
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• 2001

The acousto-optical spectrometer is designed by using 1 GHz bandwidth acousto-optic deflector for radio signal analysis. This system is a high resolution wide band spectrometer which uses I GHz bandwidth and a total of 2,048 channel charge coupled device. When we measured the spectrums of signals deflected by acousto-optical spectrometer, we confirmed the stability of the total system by repetitive observations of the same frequency, and each part of the system worked well. We installed this system onto 60 cm radio telescope, and observed 12CO(J= 1 ∼0) emission lines around CRL 2688, IRC 10216 and NGC 5005 Galaxy center. We could observe effectively very narrow band width radio spectrum as well as wide band radio spectrum. We also confirmed high sensitivity and resolution in observation of 12CO(J-10) omission line of NGC 5005 Galaxy center which is a weak signal.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2713-2718
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• 2010

To improve the CNT's dispersion, we tried to chemically modify the surface of MWNT with the butyllithium and the hexyllithium solution in sonicated reactor. The functionalized-MWNTs were characterized by Fourier transform infrared spectrometer(FT-IR) and Raman spectrophotometer. Also, we investigated the amount of alkyl moiety incorporated into MWNT's surface with Thermal gravimetric analyzer(TGA) and dispersibility in various organic solvents. Finally, we could find organic content was about 5% of the functionalized MWNT and dispersibility was enhanced in some solvents having intermediate solubility parameter.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.110-110
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• 2021

사회적, 환경적으로 크고 작은 문제를 일으키는 녹조현상은 수생태계에서 1차 생산자로 없어서는 안 될 조류의 과대 성장으로 인해 주로 나타난다. 담수조류는 크게 녹조류, 남조류, 규조류 3종으로 나누어지며, 특히 남조류는 계절별 천이에 따른 발생 시 과대 성장하는 특성으로 인해 녹조현상에 가장 큰 원인이 된다. 이러한 녹조현상의 원인에 따라 환경부에서는 발령기준 항목을 chl-a와 남조류 세포수에서 2016년 이후 남조류 세포수 만으로 발령기준 항목을 개정하였다. 따라서, 녹조현상에 대한 신속한 대처를 위해서는 남조류에 대한 분포에 대해 파악하는 것이 가장 우선시 되며 이를 위해 신속한 모니터링을 필요로 한다. 하지만 현재 조류 모니터링을 위해서는 직접 채수를 통한 검경 또는 Lisst, YSI와 같은 직접 계측 센서를 활용하여 모니터링을 진행을 하고 있으며 이러한 점, 선 단위의 측정은 전반적인 조류 분포 및 현황에 대하여 파악과 신속한 모니터링에 한계가 있다. 이러한 한계에 대안으로 위성영상, 다중분광 및 초분광 영상을 활용한 면단 위의 원격 모니터링을 통해 신속하고 하천 내 전반적인 조류 농도 분석을 위한 연구가 다양하게 진행되고 있다. 본 연구에서는 UAV를 활용한 초분광센서를 이용하여 하천과 일정한 반사율을 가지는 반사천을 촬영하고 취득한 초분광영상 보정 및 분석을 진행하였다. 최적 밴드 비를 산정하고 YSI를 통한 Chl-a 결과를 이용하여 분광 특성별 맵핑을 통한 공간적 분포의 조류 농도를 산정하고자 한다.

• Applied Biological Chemistry
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• v.48 no.2
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• pp.183-188
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• 2005

This study was conducted to develop a method for the quantitative determination of soil clay content by spectophotometry. The optimum wavelength obtained with reference clay minerals for spectrophotometry was 500 nm. For the proposed spectrophotometry, 0.5 g of soil sample was put in the 250 ml Erlenmeyer flask and 100 ml dispersing agent was added. After shaking the flask at 130 rpm with a mechanical shaker overnight, the flask was removed from the shaker and was shaken up-and-down for 30 seconds. With a micro-pipet, 4 ml of the suspension was transferred into the previously-inserted cell and the absorbance was measured instantly. Results by the spectrophotometry for clay content analysis were compared with those by the conventional sedimentation technique (the pipet method). The proposed equation was $y\;=\;38.03x_1-0.17x_2-1.17$, where y, $x_1$, and $x_2$ were clay content (%) by the pipet method, water content corrected clay content (%) by spectrophotometry, and organic matter content ($g{\cdot}kg^{-1}$), respectively. The regression coefficient for the equation was $r\;=\;0.984^{**}$, indicating highly significant correlation between the results of the two methods.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.4
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• pp.421-430
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• 2010

Image segmentation technique is becoming increasingly important in the field of remote sensing image analysis in areas such as object oriented image classification to extract object regions of interest within images. This paper presents a new method for image segmentation in High Resolution Remote Sensing Image based on Improved Seeded Region Growing (ISRG) and Region merging. Firstly, multi-spectral edge detection was done using an entropy operator in pan-sharpened QuickBird imagery. Then, the initial seeds were automatically selected from the obtained multi-spectral edge map. After automatic selection of significant seeds, an initial segmentation was achieved by applying ISRG to consider spectral and edge information. Finally the region merging process, integrating region texture and spectral information, was carried out to get the final segmentation result. The accuracy assesment was done using the unsupervised objective evaluation method for evaluating the effectiveness of the proposed method. Experimental results demonstrated that the proposed method has good potential for application in the segmentation of high resolution satellite images.

• Journal of The Korean Society of Grassland and Forage Science
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• v.40 no.4
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• pp.196-202
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• 2020

Rye, whole-crop barley and Italian Ryegrass are major winter forage species in Korea, and yield monitoring of winter forage species is important to improve forage productivity by precision management of forage. Forage monitoring using Unmanned Aerial Vehicle (UAV) has offered cost effective and real-time applications for site-specific data collection. To monitor forage crop by multispectral camera with UAV, we tested four types of vegetation index (Normalized Difference Vegetation Index; NDVI, Green Normalized Difference Vegetation Index; GNDVI, Normalized Green Red Difference Index; NGRDI and Normalized Difference Red Edge Index; NDREI). Field measurements were conducted on paddy field at Naju City, Jeollanam-do, Korea between February to April 2019. Aerial photos were obtained by an UAV system and NDVI, GNDVI, NGRDI and NDREI were calculated from aerial photos. About rye, whole-crop barley and Italian Ryegrass, regression analysis showed that the correlation coefficients between dry matter and NDVI were 0.91~0.92, GNDVI were 0.92~0.94, NGRDI were 0.71~0.85 and NDREI were 0.84~0.91. Therefore, GNDVI were the best effective vegetation index to predict dry matter of rye, wholecrop barley and Italian Ryegrass by UAV system.