• Journal of Korean Society of Water and Wastewater
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• v.32 no.6
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• pp.573-581
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• 2018

The purpose of this study is to evaluate the fixed wing type domestic UAV for monitoring of algae bloom in aquatic environment. The UAV used in this study is operated automatically in-flight using an automatic navigation device, and flies along a path targeting preconfigured GPS coordinates of desired measurement sites input by a flight path controller. The sensors used in this study were Sequoia multi-spectral cameras. The photographed images were processed using orthomosaics, georeferenced digital surface models, and 3D mapping software such as Pix4D. In this study, NDVI(Normalized distribution vegetation index) was used for estimating the concentration of chlorophyll-a in river. Based on the NDVI analysis, the distribution areas of chlorophyll-a could be analyzed. The UAV image was compared with a airborne image at a similar time and place. UAV images were found to be effective for monitoring of chlorophyll-a in river.

• Journal of Practical Agriculture & Fisheries Research
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• v.24 no.2
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• pp.5-11
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• 2022

Prunus × yedoensis is a representative tree species in residential areas often used as a street tree or park tree, with its popularity due to splendid flowers in the spring. We investigated plant growth, photosynthesis, chlorophyll, and carotenoid concentrations of Prunus yedoensis at 400ml/pot, 1,000ml/pot, and 2,000ml/pot Irrigation treatments. Overall growth indices such as tree height, diameter at root collar (DRC), and total dry weight could be ranked in the decreasing order "2,000ml/pot > 1,000ml/pot > 400ml/pot.". However, 2,000ml/pot featured decreased photosynthesis and total chlorophyll carotenoid contents than 1,000ml/pot treatment after July. And also, The 1,000ml/pot treatment showed relatively high photosynthetic activity and chlorophyll contents. These results suggested that the cultivation of Prunus yedoensis under 1,000ml/pot Irrigation treatment(soil water contents 25~35%) showed the best condition in growth.

• Ocean and Polar Research
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• v.45 no.3
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• pp.113-123
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• 2023

Humic substances are refractory organic compounds that are relatively low in biological activity but known to stimulate phytoplankton growth in estuarine and marine environments. The effect of humic substances on phytoplankton growth was investigated in the seawater zone of the Yeongsan River estuary where an episodic anthropogenic freshwater is discharged, affecting its water properties directly. Water samples and data of water properties were collected at three stations (Sts. A-C) along the channel of the seawater zone in February, May, August and November, 2009. The collected water samples were incubated after humic acids (HA) were added in mesocosm experiments. Phytoplankton (chlorophyll-a) were fractionated into net- (> 20 ㎛) and nano-size (< 20 ㎛) to examine the response of phytoplankton according to size. Their response to HA treatment was assessed by repeated measures analysis of variance (RM-ANOVA). The experiments showed that phytoplankton biomass (chlorophyll-a) significantly increased after HA were added at the stations near the sea dike. Especially, nano-sized chlorophyll-a concentrations increased significantly throughout the seasons. This indicates that understanding the behavior of refractory organic matters such as humic substances is required to better manage altered estuarine ecosystems including the Yeongsan River estuary which are affected by episodic discharge of freshwater from sea dikes.

• Korean Journal of Ecology and Environment
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• v.41 no.4
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• pp.472-484
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• 2008

The calibrated Andong Reservoir hydro-dynamic module (PART I) of the 2-dimensional hydrodynamic and water quality model, CE-QUAL-W2 [v3.2], was applied to examine the dynamics of total phosphorus, and chlorophyll $\alpha$ concentration within Andong Reservoir. The modeling effort was supported with the data collected in the field for a five year period. In general, the model achieved a good accuracy throughout the calibration period for both chlorophyll ${\alpha}$ and total phosphorus concentration. The greatest deviation in algal concentration occurred on $10^{th}$ October, starting at the layer just beneath the surface layer and extending up to the depth of 35 m. This deviation is principally attributed to the effect of temperature on the algal growth rate. Also, on the same date, the model over-predicts hypolimnion and epilimnion total phosphorus concentration but under-predicts the high concentrated plume in the metalimnion. The large amount of upwelling of finer suspended solid particles, and re-suspension of the sediments laden with phosphorus, are thought to have caused high concentration in the epilimnion and hypolimnion, respectively. Nevertheless, the model well reproduced the seasonal dynamics of both chlorophyll a and total phosphorus concentration. Also, the model tracked the interflow of high phosphorus concentration plume brought by the turbid discharge during the Asian summer monsoon season. Two different hypothetical discharge scenarios (discharge from epilimnetic, and hypolimnetic layers) were analyzed to understand the response of total phosphorus interflow plume on the basis of differential discharge gate location. The simulated results showed that the hypolimnetic discharge gate operation ($103{\sim}113\;m$) was the most effective reservoir structural control method in quickly discharging the total phosphorus plume (decrease of in-reservoir concentration by 219% than present level).

• Journal of Ginseng Research
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• v.13 no.2
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• pp.165-168
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• 1989

Ginseng plants in the 2nd year were grown under the shade (90-95%) of colored cellophane films at $15^{\circ}C$ in a natural light phytotron. Relative root grown (final/initial) was in decreasing order of blue, green, white, yellow and red. The growth of aerial part, especially stem length was poorest in blue light with relative root growth negatively correlated with stem length. In this relation each color showed specific domain. Stem length showed positive linear correlation with leaf area per plant in each and among light though it was not significant in red light. The content and ratio of chlorophyll a and b in leaf were in the decreasing order of White, Blue, Green, Red and Yellow. There is positive correlation between chlorophyll a and chlorophyll b, and between total chlorophyll and chl:a/b ratio. Blue color shade is expected to be beneficial for ginseng production.

• Journal of Environmental Science International
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• v.2 no.4
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• pp.255-270
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• 1993

Effects of polyamines on chlorophyll and protein content, and $\delta$-aminolevulinate dehydratase(ALAD) activity were investigated during the greening of mung bean cotyledons. Polyamines stimulated chlorophyll formation in greening cotyledons, and this effect was enhanced by KCl. The changes in protein content were similar to the changes for chlorophyll content. The excision entailed an increase in ALAD activity. Then a decrease appeared after 48 h incubation on water in the dark. It was more precocious in the light, but was accelerated when the cotyledons were illuminated after a dark preincubation. Putrescine had little effect on ALAD activity in the dark. In the light, putrescine prevented the decrease in ALAD activity and enhanced this activity when a dark preincubation preceded illumination. KCl had a slight stimulating effect in the dark, but was uneffective in the light. The combination putrescine＋KCl was devoid of stimulating effect. The results obtained suggest that plastid development of mung bean cotyledons during greening was affected by polyamines and light and that polyamines may play a role in the regulation of plastid development.

• Journal of Ecology and Environment
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• v.36 no.4
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• pp.255-265
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• 2013

This study was conducted to determine the extent of drought resistance based on physiological responses of Calystegia soldanella under water deficit. In order to investigate the changes of plant growth, stomatal density, photosynthesis, chlorophyll fluorescence, the contents of chlorophyll and carotenoid, osmolality, total ion contents, the contents of carbohydrate and proline, C. soldanella was grown under well watered and drought stressed conditions for 12 days. In this study, water-deficit resulted in remarkable growth inhibition of C. soldanella. The effect of water-deficit on plant growth was associated with low osmotic potential of soil. On day 12 after drought treatment, dry weight, relative water contents, number and area of leaves and stem length were lower than those of control. The stomatal conductance and net photosynthetic rate were significantly reduced in water stressed plant to regulate inner water contents and $CO_2$ exchange through the stomatal pore. Chlorophyll fluorescence and chlorophyll contents were not different in comparison with the control, indicating that the efficiency of photosystem II was not affected by drought stress. This results could be explained that water-deficit in C. soldanella limits the photosynthetic rate and reduces the plant's ability to convert energy to biomass. A significant increase in total ion contents and osmolality was observed on day 7 and day 12. Accumulation of proline in leaves is associated with the osmotic adjustment in C. soldanella to soil water-deficit. Consequently, this increase in osmolality in water stressed plant can be a result in the increase of ion contents and proline.

• Journal of the Korean Society of Food Science and Nutrition
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• v.16 no.4
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• pp.300-305
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• 1987

Changes in pigments of freeze dried grasshopper in refrigerator were determined to asses the storage stability. In storage at $5^{\circ}C$, chlorophyll contents were drastically decreased but pheopytins were increased. The degradation of chlorophylls get under controlled with vacuum package. The pigments extracted from 98 days stored samples were fractionated by silicic acid column and obtained 3 portions (3a, 3b and 3d). These portions were compared Rf values (0.75, 0.56, 0.50, respectively) and absorption spectra (408, 666nm; 419, 651nm; 433, 655nm, respectively) with that of standard and were identifed pheophytin a and b and 'changed' chlorophyll a. Especially, pheophytins a and b were great strength accelerated to lipid oxidation.

• Korean Journal of Environmental Biology
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• v.20 no.2
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• pp.146-151
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• 2002

The primary productivity and physicochemical factors were surveyed seasonally in Gangjin bay from February to October in 1998. The determination of the Primary Productivity Was performed in Situ by isotope-method using NaH/sup 14/CO/sub 3/. The range of primary productivity was 2.78 mgC m/sup -3/ hr/sup -1/-4.92 mgC m/sup -3/ hr/sup -1/ according to seasons. The primary productivity showed the highest value in summer, followed by those of winter, autumn and spring. The primary productivities of station 1, 2 which are located the upper area, were lower than those of station 3, 4, 5 and 6. The correlations showed that the primary productivity correlated with chlorophyll a, underwater light intensity but reversely correlated with suspended solids. These results suggested that the primary productivity in Gangjin Bay was mainly influenced by the inflow of freshwater from Tamjin River.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.2
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• pp.173-181
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• 1993

Seasonal distributions of nutrients and particulate organic matter were investigated in Asan Bay, Korea. Most of nutrients were high in August and low in February. The atomic ratios of inorganic nitrogen to phosphorous were close to Redfield ratio except in May when the ratio was 24.8. In May, nutrient concentrations except phosphorous decreased with salinity until $31.5{\sim}32.0%0$, but the concentrations increased again with salinity, impling that there were nutrient input sources within the estuary. Howerer, significant inverse relationships between nutrients and salinity in August suggest that nutrient sources were river discharge. Maximum chlorophyll a concentrations occurred in May. Relatively low ratios of $R_b$ to $R_a$($R_b$: fluorescence before acidification; $R_a$: fluorescence after acidification) during the study periods indicate that phytoplankton were not in good physiological condition. Relatively low ratio of particulate biogenic silica(PBSi) to particulate organic carbon(POC) and high ratios of PBSi and POC to chlorophyll a during the study periods suggest input of non-living detrital PBSi and POC from bottom in Asan Bay, where strong tidal mixing occurs.