• Korean Journal of Environment and Ecology
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• v.28 no.3
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• pp.302-313
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• 2014

This study was conducted to compare the characteristics of fish distribution according to sand type stream and cobble type stream the 4 stream selected every season. The collected Korea endemic species during the survey period were 24, including Acheilognathus gracilis. Dominant species of Hongcheon stream and Muju Namdae stream was Zacco koreanus, each accounting for 39.9% and 28.4% in order, and dominant species in Yanghwa stream was Rhodeus notatus, 13.6%, and those in Gap stream was Z. platypus, by 26.0%. As a result of community analysis, dominant index was 0.27~0.63, diversity index was 1.92~2.67, evenness index was 0.6~0.79, richness index was 3.09~3.53, and dominant index was the highest in Hongcheon stream, and the indices of diversity, evenness and richness were the highest in Yanghwa stream. As a result of tolerance guild analysis, Hongcheon stream and Muju Namdae stream with a variety of substrates accounted for relatively higher rate by 50.1% and 46.4% in sensitive species respectively, and Yanghwa stream and Gap stream with greater sand substrates had 0.5% and 5.3% scarce rate of sensitive species. As a result of similarity analysis using the species, population and substrate structures of the fisheries appeared in each stream, cobble type streams such as Hongcheon stream and Muju Namdae stream were the most similar by 50.4% in species and population, 95.2% in bed structure. As a result of IBI analysis, Hongcheon stream and Muju Namdae stream appeared as 'Class A,' Yanhwa stream and Gap stream as 'Class B' and the two groups of cobble type stream and sand type stream were divided as a result of principal components analysis.

• Applied Biological Chemistry
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• v.47 no.1
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• pp.61-66
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• 2004

70% ethanolic extracts were prepared from the three mutant rice cultivars with giant embryo termed Shinsunchal-giant embryonic rice, Whachung-giant embryonic rice and Nampung-giant embryonic rice, and its antioxidative and antimutagenic properties were evaluated and compared. For analysing antioxidativity, various antioxidative indices, such as electron donating ability to DPPH radical, scavenging capacity to hydroxyl radicals generated by Fenton reaction, scavenging capacity to superoxide radicals generated by HPX/XOD system, inhibitory effect on autoxidation of linoleic acid and inhibitory effect on membrane lipid peroxidation derived from rabbit erythrocyte ghost, were determined. For analysing antimutagenicity, suppressive effects on mutagenesis induced by the chemical mutagen, mitomycin C, were measured using E. coli PQ 37 as a indicator cell. The results showed that for both antioxidativity and antimutagenicity the giant embryonic rices were more effective compared to the general cooking rice, Among the giant embryonic rice cultivars, Nampung-giant embryonic rice tended to be most effective, showing its scavenging activity to DPPH radical, superoxide radical and hydroxyl radical, and inhibitory activity to lipid peroxidation was 2,3-, 3,3-, 1.7-, and 2.5-fold greater than those of normal rice, respectively.

• Korean Journal of Ecology and Environment
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• v.47 no.4
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• pp.328-336
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• 2014

Nakdan weir, which is located in the second weir among the 8 weirs of Nakdong River, had been constructed from Nov. 2009 to Nov. 2011. To analyze the effect of Nakdan weir construction on benthic macroinvertebrates, we studied 2 sites around Nakdan weir (upstream and downstream) from 2007 to 2014. The average numbers of species and individuals were decreased after the construction (in 2012~2014, 51 species $895inds.\;m^{-2}$) than before construction (in 2007~2009, 25 species $84inds.\;m^{-2}$), especially in upstream site of Nakdan weir. After the construction, especially in 2012, dominance indices (DI) were increased by the decline of some specific taxon population, such as Ephemeroptera and Trichoptera, etc. After construction, individual ratios of GC (Gathering Collectors) and P (Predator) of FFGs (Functional feeding groups) and BU (Burrowers) of HOGs (Habitat orientation groups) were higher than before construction. So the results of this study indicate that the changes by a weir construction, such as the decline of shallow depth area, reduced velocity of water flow and increased ratio of sand bed, etc., can affect the benthic macroinvertebrate communities variously.

• Ecology and Resilient Infrastructure
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• v.2 no.1
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• pp.54-63
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• 2015

This study was conducted to investigate the flora and vegetation structure at a 15-year-old artificial wetland for the water purification in Jincheon, Korea. The percentage of species number of obligate wetland plants and facultative wetland plants totaled 40%, whereas that of obligate upland plants and facultative upland plants was 57%. This result showed that the artificial wetland in the study experienced terrestrialization. The number of annual and biennial plants that are pioneer vegetation in a successional stage was lower than that of perennial herbs as a result of the long-term stabilization of vegetation. From the results of DCA (detrended correspondence analysis), water depth played an important role on the classification of vegetation structure in an old artificial wetland. Species diversity was higher in the terrestrialized plant communities such as Iris pseudacorus and Aster koraiensis than in any other wetland communities. Plant communities could be classified according to the wetland indices; obligate upland for A. koraiensis community, facultative wetlands for Carex dispalata var. dispalata and I. pseudacorus community, and obligate wetlands for Nymphoides peltata, Nymphaea tetragona, Phragmites communis, Potamogeton maackianus, and Typha angustifolia community. In conclusion, this result suggests that wetland vegetation should be maintained against terrestrialization through the proper management of sedimentation and hydrological regime in an artificial wetland.

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.148-156
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• 2017

In this study, we analyzed the relationship between phytoplankton community and physicochemical factors in 12 lakes located in Jeollanam-do based on the data surveyed from March to November 2014. Totally, 297 species of phytoplankton were identified including 98 Bacillariophyceae, 148 Chlorophyceae, 23 Cyanophyceae and 28 other phytoplankton taxa. The standing crops ranged from 124 to $59,148cells\;mL^{-1}$ and showed the highest in August with the increase of Cyanophycean cells. The self-organizing map (SOM) was optimized into $9{\times}6$ grid and was classified into 5 clusters based on the similarity of environmental factors and phytoplankton indices. The SOM results showed that phytoplankton communities had positive relationship with water temperature, SS, DO, BOD, TP and Chl-a, whereas low relationship with pH, TN, $NH_3-N$, $NO_3-N$, $PO_4-P$ and Conductivity. In Pearson's correlation coefficient, relationship between environmental factors and phytoplankton communities showed similar results with SOM.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.5
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• pp.598-607
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• 2016

This study was conducted to evaluate the amount of nitrogen (N) top dressing based on the normalized difference vegetation indices (NDVI) by ground based sensors for leaf perilla under the polyethylene house. Experimental design was the randomized complete block design for five N fertilization levels and conventional fertilization with 3 and 4 replications in Gumsan-gun and Milyang-si field, respectively. Dry weight (DW), concentration of N, and amount of N uptake by leaf perilla as well as NDVIs from sensors were measured monthly. Difference of growth characteristics among treatments in Gumsan field was wider than Milyang. SPAD-502 chlorophyll meter reading explained 43.4% of the variability in N content of leaves in Gumsan field at $150^{th}$ day after seedling (DAS) and 45.9% in Milyang at $239^{th}$ DAS. Indexes of red sensor (RNDVI) and amber sensor (ANDVI) at $172^{th}$ day after seedling (DAS) in Gumsan explained 50% and 57% of the variability in N content of leaves. RNDVI and ANDVI at $31^{th}$ DAS in Milyang explained 60% and 65% of the variability in DW of leaves. Based on the relationship between ANDVI and N application rate, ANDVI at $172^{th}$ DAS in Gumsan explained 57% of the variability in N application rate but non significant relationship in Milyang field. Average sufficiency index (SI) calculated from ratio of each measurement index per maximum index of ANDVI at $172^{th}$ DAS in Gumsan explained 73% of the variability in N application rate. Although the relationship between NDVIs and growth characteristics was various upon growing season, SI by NDVIs of ground based remote sensors at top dressing season was thought to be useful index for recommendation of N top dressing rate of leaf perilla.

• Journal of Biomedical Engineering Research
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• v.25 no.6
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• pp.439-445
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• 2004

Diffusion tensor image(DTI) exploits the random diffusional motion of water molecules. This method is useful for the characterization of the architecture of tissues. In some tissues, such as muscle or cerebral white matter, cellular arrangement shows a strongly preferred direction of water diffusion, i.e., the diffusion is anisotropic. The degree of anisotropy is often represented using diffusion anisotropy indices (relative anisotropy(RA), fractional anisotropy(FA), volume ratio(VR)). In this study, FA images were obtained using different gradient schemes(N=6, 11, 23, 35. 47). Mean values and the standard deviations of FA were then measured at several anatomic locations for each scheme. The results showed that both mean values and the standard deviations of FA were decreased as the number of gradient directions were increased. Also, the standard error of ADC measurement decreased as the number of diffusion gradient directions increased. In conclusion, different gradient schemes showed a significantly different noise performance and the schem with more gradient directions clearly improved the quality of the FA images. But considering acquisition time of image and standard deviation of FA, 23 gradient directions is clinically optimal.

• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.76-83
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• 2022

We attempted to estimate potential habitats of Clithon retropictus and to determine the community structure of benthic macroinvertebrates by presence of C. retropictus. 2016 to 2018 database of "Survey and Assessment of Estuary Ecosystem Health" by the Ministry of Environment were used to identify the distribution site of C. retropictus. The occupancy model was applied to estimate the potential habitat of C. retropictus. Four diversity indices were used to confirm the community structure of benthic macroinvertebrates. C. retropictus was found in the southern coast area and part of the east coast, and this pattern was consistent with previous studies. Additionally, the occupancy model predicted that a potential habitat of C. retropictus could appear in the west coast area. The community structure of benthic macroinvertebrates was relatively high at the site with C. retropictus than the site without C. retropictus. Therefore, the occupancy model can be considered when conserving C. retropictus inhabiting a limited area. Additionally, C. retropictus can be used to the indicator species that can represent the brackish water environment.

• Journal of Korean Society on Water Environment
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• v.34 no.2
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• pp.183-201
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• 2018

The tolerance of Korean benthic macroinvertebrates to organic pollution has been analyzed since the early 1990s. However, considering the fact that there have been related studies carried out in some European countries since the early 20th century, the history of the research in Korea is very short and there is still much knowledge to supplement. We revised the saprobic valency, the saprobic value and the indicator weight value of 190 benthic macroinvertebrates taxa through the data of water quality and individual abundance collected from 7,086 sampling units in Korea from 2008 to 2014. The individual abundance of Uracanthella (Ephemeroptera) as a representative, one of the most common and abundant taxa in Korea, showed a typical lognormal distribution to 5-day biochemical oxygen demand (BOD5) concentration, and a normal distribution to the class interval of BOD5 concentration according to saprobic series. The value combining the mean individual abundance and the relative frequency of occurrence was a more efficient indicator value than that of each property alone. Benthic Macroinertebrates Index (BMI) was newly proposed as a modification of the saprobic index of Zelinka and Marvan (1961). BMI showed extremely significant correlation (determination coefficient $r^2$ > 0.6, n = 569 sites) with the concentration of BOD5, and the coefficient was a little higher than those of the previous indices. Until now, there has been very little research on the assessment of biological integrity of benthic macroinvertebrates community in Korea. While continuing researches into improve the reliability of BMI, it is necessary to develop multimetric indices for evaluating the integrity, including the composition of species and functional guilds, and the richness and diversity of the community.

• Journal of Biosystems Engineering
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• v.41 no.2
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• pp.126-137
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• 2016

Purpose: The overall objective of this study was to evaluate the vegetation fraction of soybeans, grown under different cropping conditions using an unmanned aerial vehicle (UAV) equipped with a red, green, and blue (RGB) camera. Methods: Test plots were prepared based on different cropping treatments, i.e., soybean single-cropping, with and without herbicide application and soybean and barley-cover cropping, with and without herbicide application. The UAV flights were manually controlled using a remote flight controller on the ground, with 2.4 GHz radio frequency communication. For image pre-processing, the acquired images were pre-treated and georeferenced using a fisheye distortion removal function, and ground control points were collected using Google Maps. Tarpaulin panels of different colors were used to calibrate the multi-temporal images by converting the RGB digital number values into the RGB reflectance spectrum, utilizing a linear regression method. Excess Green (ExG) vegetation indices for each of the test plots were compared with the M-statistic method in order to quantitatively evaluate the greenness of soybean fields under different cropping systems. Results: The reflectance calibration methods used in the study showed high coefficients of determination, ranging from 0.8 to 0.9, indicating the feasibility of a linear regression fitting method for monitoring multi-temporal RGB images of soybean fields. As expected, the ExG vegetation indices changed according to different soybean growth stages, showing clear differences among the test plots with different cropping treatments in the early season of < 60 days after sowing (DAS). With the M-statistic method, the test plots under different treatments could be discriminated in the early seasons of <41 DAS, showing a value of M > 1. Conclusion: Therefore, multi-temporal images obtained with an UAV and a RGB camera could be applied for quantifying overall vegetation fractions and crop growth status, and this information could contribute to determine proper treatments for the vegetation fraction.