• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.5
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• pp.486-494
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• 2003

Distribution of ichthyoplanktons and its relation to environmental factors (temperature, salinity, $chlorophyll\;\alpha$) around the Youngsan River Estuary of Mokpo, southwest coast of Korea were investigated based on the samples collected bimonthly from February to December, 2001. Unidentified fish eggs were most abundant $1,345\;eggs/100m^3$ in August, while eggs of Engraulis japonicus were most abundant $63\;eggs/100m^3$ in June. A total of forty species of fish larvae and juveniles belonging to the twenty families under six orders were caught, with six gobiids, four icefishes, four croakers and three herrings being represented. Fish larvae and juveniles peaked $17,757\;inds./100m^3$ in August, which consisted of $91.02\%$ of gobiids, $3.69\%$ of gunnels and $3.67\%$ of icefishes, and they were most abundant $7,467\;Inds./100m^3$ at St. 7. Cluster analysis based on the individuals of fish larvae and juveniles showed that six months were classified into two groups at the dissimilarity 70, the first was composed of June and August and the second was February and December and April and October were not clustered with any other months. In August when species diversity index was the highest, eight stations were classified into two groups at the dissimilarity 70, the first was composed of St. 1, 3, 4, 5 and 8 and the second was St. 6, 7 and 2. As a result from correspondence analysis, there is no effect of the environmental factors with a density of fish eggs and larvae, but correlation could be found between a density of fish eggs and $chlorophyll\;\alpha.$

• The Plant Pathology Journal
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• v.16 no.3
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• pp.130-136
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• 2000

Differences in physiological and biochemical responses between sensitive and tolerant rice cultivars to ozone were investigated to develop reliable indications of early ozone damage. Three Korean local rice cultivars -sen-sitive cultivar Dongjin (DJ), moderately tolerant cultivar Hwayeong (HY) and tolerant cultivar Ilmee (IM) were exposed to ozone at the concentrations of 100 nl $\textrm{l}^{-1}$ or 200 nl $\textrm{l}^{-1}$ , 8 h per day for 10 days in a controlled-environment fumigation chamber. The rice cultivars seemed to be endurable to ozone stress at the concentration of 100 nl $\textrm{l}^{-1}$ which is frequently monitored during the growing season in summer. However, severe damage was induced and differential sensitivity was clearly noted among the rice cultivars at the higher ozone concentration. Activation of the glutathion (GR) -ascorbate peroxidase (APX) cycle was likely to be responsible for protection of rice plants against ozone exposure, relating difference in sensitivity of rice cultivars to ozone. Photosynthetic activity appeared to be one of sensitive responses, for which chlorophyll fluorescence and leaf greenness can together provide a very reliable index, a degree of photosynthetic damages by ozone. Formation of malondialdehyde (MDA) was also considered as an indication that can differentiate cultivars sensitivity to ozone. However, the changes in polyamines and total phenolics were not consistent with exposed ozone concentrations and/or ozone sensitivity of the cultivars. The behavior of polyamines and phenolics in the damaged plants at high ozone levels could be interpreted as an indication of ozone injury rather than activation of additional protection mechanisms scavenging active oxygen species formed by ozone. Several responses triggered by ozone could explain the differential sensitivity of the rice cultivars and be used as reliable indications of relative ozone damage to rice plant.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.654-655
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• 2003

Korea has experienced 10 a Cochlodinium polykrikoides red tide outbreaks during the last 10 years (1993-2002). The monitoring activities at National Fisheries Research and Development Institute (NFRDI) in Korea have been extended to all the coastal waters after the worst of fish killing by C. polykrikoides blooms in 1995. NFRDI is looking forward to finding out the feasibility of red tide detection around Korean waters using satellite remote sensing of NOAA/AVHRR, Orbview-2/SeaWiFS, IRS-P4/OCM and Terra/MODIS on real time base. In this study, we used several alternative methods including climatological analysis, spectral and optical methods which may offer a potential detection of the major species of red tide in Korean waters. The relationship between the distribution of SST and C. polykrikoides bloom areas was studied. In climatological analysis, NOAA, SeaWiFS, OCM satellite data in 20th and 26th August 2001 were chosen using the known C. polykrikoides red tide bloom area mapped by helicopter reconnaissance and ground observation. The 26th August, 2001 SeaWiFS chlorophyll a anomaly imageries against the imageries of non-occurring red tide for August 20, 2001 showed the areas C. polykrikoides occurred. The anomalies of chlorophyll a concentration from satellite data between before and after red tide outbreaks showed the similar distribution of C. polykrikoides red tide in 26th August, 2001. The distribution of the difference in SST between daytime and nighttime also showed the possibility of red tide detection. We used corrected vegetation index (CVI) to detect floating vegetation and submerged vegetation containing algal blooms. The simple result of optical absorption from C. polykrikoides showed that if we use the optical characteristics of each red tide we will be able to get the feasibility of the red tide detection.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.340-347
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• 2001

Seasonal variation of the elemental and biochemical composition of the suspended particulate matter (SPM) was investigated in terms of quantity and quality of diets for suspension feeders from July 1999 to August 2000 in two coastal bay systems of Gosung and Kangjin Bays in Korea. No clear patterns in the seasonal variations of SPM concentration were found in these two bay systems. The results indicated that the seasonal variation of SPM could not be considered the variation of food available to suspension-feeders. The simultaneous peaks in chlorophyll a and biochemical components in summer indicated that the quantity of the particulate organic matter primarily depended on phytoplankton productivity. However, no correlation between chlorophyll a and biochemical components [particulate protein (PPr), carbohydrate (PCHO) and lipid] were found, indicating that other processes might also contribute to the particulate organic matter in the period when the phytoplankton biomass was low. High C: Chl a and C:N, and carbohydrate peaks during the autumn to spring period suggested that resuspension of surface sediments was a probable process to supply the particulate organic matter. The food material, represented by summing up the total quantity of three biochemical components, was highest in spring with minor peaks during the period from autumn to the next spring, The food index, calculated as the ratio of food material to total SPM, did not generally exceed $6\%$ with short peaks during the year. Therefore, nutritional quality of SPM in the bays are relatively poor than in other more productive coastal waters in the world. Our results confirm that the measurement of a single chemical variable cannot describe fully the nutritive value of the seston available to suspension-feeders as previously proposed, and the biochemical composition of SPM can provide effective information on its origin and nutritive Quality.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.2
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• pp.92-103
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• 2003

Research and technological advances in the field of remote sensing have greatly enhanced the ability to detect and quantify physical and biological stresses that affect the productivity of agricultural crops. Reflectance in specific visible and near-infrared regions of the electromagnetic spectrum have proved useful in detection of nutrient deficiencies. Especially crop canopy sensors as a ground remote sensing measure the amount of light reflected from nearby surfaces such as leaf tissue or soil and is in contrast to aircraft or satellite platforms that generate photographs or various types of digital images. Multi-spectral vegetation indices derived from crop canopy reflectance in relatively wide wave band can be used to monitor the growth response of plants in relation to environmental factors. The normalized difference vegetation index (NDVI), where NDVI = (NIR-Red)/(NIR+Red), was originally proposed as a means of estimating green biomass. The basis of this relationship is the strong absorption (low reflectance) of red light by chlorophyll and low absorption (high reflectance and transmittance) in the near infrared (NIR) by green leaves. Thereafter many researchers have proposed the other indices for assessing crop vegetation due to confounding soil background effects in the measurement. The green normalized difference vegetation index (GNDVI), where the green band is substituted for the red band in the NDVI equation, was proved to be more useful for assessing canopy variation in green crop biomass related to nitrogen fertility in soils. Consequently ground remote sensing as a non destructive real-time assessment of nitrogen status in plant was thought to be useful tool for site specific crop nitrogen management providing both spatial and temporal information.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.4
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• pp.263-267
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• 2013

Long-term (from 1995 to 2012) data of phytoplankton biomass (chlorophyll-a, Chl-a) and water quality were analyzed to investigate trends of eutrophication in downstream of Nakdong River (Mulgum). Long-term annual average concentration of water quality parameters and phytoplankton biomass at Mulgum showed an decreasing trends for 18 years. Phytoplankton biomass was high from annually December to March. Trophic state was evaluated as the eutrophic state annually from 1995 to 2012 by TSI (trophic state index) by Aizaki. From the results of simple regression analysis, correlation coefficient between Chl-a concentration and BOD concentration was high ($r^2$ = 0.82).

• Korean Journal of Environmental Biology
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• v.28 no.3
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• pp.125-132
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• 2010

In order to assess the effect of pollution on marine ecosystem, we examined the plankton health assessment at 16 stations during summer season in Jinhae Bay. The organic and inorganic pollutant sources (dissolved organic carbon; DOC, chemical oxygen demand; COD and Chlorophyll a; Chl.a), including planktonic orangism such as enterobacteria Escherichia coli, heterotrophic bacteria (HB), autotrophic nano-flagellates (ANF), heterotrophic nano flagellates (HNF), ciliate and harmful algal bloom species (HABs) were used to characterize marine ecosystem health assessment. Of these, we tentatively selected those items Chl.a, HABs, HB and E. coli for plankton health index (PHI). Also, the scoring criteria for each metric were based on a statistical analysis and then, the grades are rated on four levels. As a result, the ecological assessment of these data reveals that PHI in Jinhae Bay is rated as "Good or fair" for overall conditions. The present study suggests that the PHI might be considered as one of important management tool to assess marine ecosystem health of Jinhae Bay.

• Journal of environmental and Sanitary engineering
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• v.10 no.2
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• pp.36-45
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• 1995

Physicochemical environments and phytoplankton community in the nakdong river middle basin were investigated during a period of 1 year from Nov. 1993 to Oct. 1994. The ranges of Physicochemical environment factors in the nakdong river middle basin were $3.6~27.4{\circ}C$ for temperature, 7.1~9.3 for pH, $7.1~12.7mg/{\ell}$for DO, $0.7~2.1mg/{\ell}$ for BOD, $31~52mg/{\ell}$ for alkalinity, $2.101~3.3mg/{\ell}$ for T-N, $0.052~0.099mg/{\ell}$ for T-p, $5.4~92.3mg/m^{3}$ for chlorophyll-a. The number of Phytoplankton was lowest in Jan. that is, 244ce11s/ml and that was highest in Sep. 1201 cells/ml. The increase of dominant genera were correlated with the total nomber of phytoplanktons. Bacillariaceae, chlorophyceae, cyanophyceae, and euglenophlrceae were to 74.5%, 20%, 3.5%, and 2.2% respectively. Bacillariaceae were abundant during all the year round except for Jun, Jul, Aug. Chlorophyceae were plentiful in Jun, Jul, Aug. Tase-and odor-causing algae and filter clogging algae were 72% in Nov. and 93.5% in Jun. They were abundant all the year round except for winter, so they influenced on the treatment of tap water system. They belong to the general asterionella, cyclotella, melosira, nitzschia of bacillariaceae and actinastrum, pediastrum of chlorophyceae. Dominace index was low in winter and high in umber. Diversity index and equitability index were low in summer and high in winter. Therefore, the structure of phytoplankton community of the nakdong river middle basin was different form season to season.

• Journal of Korean Society on Water Environment
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• v.35 no.3
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• pp.271-277
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• 2019

Korean Trophic State Index ($TSI_{KO}$) was developed in 2006, and was composed of COD ($COD_{Mn}$ based on permanganate method), Chlorophyll a (Chl.a) and total phosphorus (TP). However, $COD_{Mn}$ usually represents only 50-60% of total organic matter in stream or lake water due to low oxidizing power of permanganate. This study investigated the relationship between TOC and $COD_{Mn}$ based on the average data for the whole layer in 81 lakes in Korea, during the period 2013-2017. As a result, $COD_{Mn}$ was found to be 1.54 times more than TOC in 66 of the freshwater lakes and 3 brackish lakes (TOC measured using thermo-oxidation method). TOC was about a quarter of $COD_{Mn}$ in 8 coastal lakes (TOC measured using UV-persulfate oxidation method), and it appeared to be underestimated due to chloride interference. Using the data of 69 lakes with exception of 12 brackish lakes, $TSI_{KO}$(TOC) was developed based on the correlation between TOC and $COD_{Mn}$, while $TSI_{KO}$(COD) was replaced with $TSI_{KO}$(TOC). However, for trophic state assessment of brackish lakes, the $TSI_{KO}$(TOC) can only be utilized in case that TOC is measured through thermo-oxidation method. The determination coefficient of $TSI_{KO}$(Chl) to $TSI_{KO}$(COD) in 66 freshwater lakes and 3 brackish lakes was 0.83, while that to $TSI_{KO}$(TOC) was 0.68. This difference could be attributed to the recalcitrant organic part of TOC.

• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.4
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• pp.340-348
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• 2021

Continuous monitoring of RGB (Red, Green, Blue) vegetation indices is important to apply remote sensing technology for the estimation of crop growth. In this study, we evaluated the performance of eight vegetation indices derived from soybean RGB images with various agronomic parameters under drought stress condition. Drought stress influenced the behavior of various RGB vegetation indices related soybean canopy architecture and leaf color. In particular, reported vegetation indices such as ExGR (Excessive green index minus excess red index), Ipca (Principal Component Analysis Index), NGRDI (Normalized Green Red Difference Index), VARI (Visible Atmospherically Resistance Index), SAVI (Soil Adjusted Vegetation Index) were effective tools in obtaining canopy coverage and leaf chlorophyll content in soybean field. In addition, the RGB vegetation indices related to leaf color responded more sensitively to drought stress than those related to canopy coverage. The PLS-DA (Partial Squares-Discriminant Analysis) results showed that the separation of RGB vegetation indices was distinct by drought stress. The results, yet preliminary, display the potential of applying vegetation indices based on RGB images as a tool for monitoring crop environmental stress.