• Journal of Wetlands Research
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• v.18 no.4
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• pp.413-423
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• 2016

Effects of the design flood share of the Kyeongpo retarding basin, which has a function for flood control of the Kyeongpo river assigned to the Kyeongpo prickly water lily wetland, on the Kyeongpo lake and the downstream of Kyeongpo river were analyzed on the bassis of the hydraulic experiments and the numerical simulations using RMA-2 model. Reproducing a complex water flow system of the area of Kyeongpo lake, the unsteady flow simulations were performed. The data obtained in hydraulic experiments were used to determine parameters of the numerical model which simulated the flows for various flood scenarios in the downstream area of Kyeongpo river. With increasing the design flood share rates in the retarding basin, the water level was increased in the lake and is decreased in the river. The characteristics of flood flow interaction between Kyeongpo river and Kyeongpo lake were understood. These results may be used to management the Kyeongpo lake during flood season.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6877-6883
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• 2014

The continuous social development has led to increasing pollution in lakes. This study proposed the LVRI (Lake Vulnerability Resilience Indicator) based on the vulnerability assessment of climate change for an environmental risk assessment in lakes sufferign water pollution in an integrated aspect of the characteristics in lake watersheds. A total of 11 representative assessment factors were selected and constructed for 6 lake basins in the Geum River Watershed to calculate the exposure, sensitivity and adaptation indicators in a vulnerability assessment classification system. The weight coefficients for assessment factors of the LVRI were also calculated using the Entropy method. This study also compared the rank results of the lake environmental risk with/without the weight coefficients of assessment factors for the practical application of the proposed lake environmental risk assessment method. The lake environmental risk results estimated in this study can be used for long-term water quality analysis and management in lakes.

• Ocean and Polar Research
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• v.25 no.4
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• pp.459-468
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• 2003

Annual variation of water qualities in the Shihwa Lake were observed 18 times from June 1996 to October 2001. We studied at the station of the upper streams and near the water gate of lake. After the flow of the outer seawater through the water gate, the surface salinity in Shihwa Lake increased to the range of 25-30 psu in both stations after October 1998. Due to the declination of the salinity differences between the surface and the bottom water, the pycnocline in which had existed until 1997 has weakened, and made the water column mix vertically. This led to the improvement of anoxic/hypoxic environment at bottom waters after April 1998. However, despite the continuous flow of the outer seawater, the concentrations of chlorophyll-a at surface layer were varied from $2{\mu}g/l\;to\;60{\mu}g/l$, and these values indicated the eutrophication. The following organic matter load was greatly influencing the surface layer's COD concentration. During the rainy season, the salinity at the surface layer to the below 15 psu resulting in stratification between the surface and bottom layer. Organic matters that were provided from the surface layer to the bottom layer due to active primary production in the year exhausted dissolved oxygen at the bottom layer, and the bulks of organic matters at bottom gave rise to hypoxic or anoxic environment. It was observed that the enrichment of ammonia and phosphate were main factors to worsen the water quality of the Shihwa Lake. The results of examining the annual variations in Shiwha Lake through principal component analysis shown that water characteristics in the rainy season were similar with those before input of outer sea water.

• Korean Journal of Microbiology
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• v.31 no.1
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• pp.85-92
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• 1993

To investigate the eutrophication process and pollution characteristics in Paldang Lake, Korea, water and sediment samples were analysed during July 1986~June 1987. The transparency, chlorophyll-a concentration, dissolved oxygen concentration and biochemical oxygen demand in Paldang Lake ranged 0.5~3 m, 3-17 ${\mu}gI^{-1}$, 7.2~12.3 ppm and 0.5~2.3 ppm, respectively. Heterotrophic bacterial number fluctuated seasonally between $3.0{\times}10^{3}/ml and 5.0{\times}10^{5}/ml$ in the water column and between $2{\times}10^{6} and 1{\times}10^{8}$ in the I g dry sediment. Water turbulence and water quality of up-stream seem to play important roles for determining the water quality in Paldang Lake particularly where the hydraulic retention time is so short as about 5 days. The present water quality in Paldang Lake according to the criteria of lake water quality was shown to be between mesotrophic and eutrophic state by secchi depth(O.5 ~ 3 m) and chlorophyll-a concentration (3~17 ${\mu}gI^{-1}$). The distribution of coliform bacteria showed that the pollution was mainly due to the human activities in this area and it is needed to establish countmeasurements for the problems.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.53-53
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• 2015

Basin-scale motions in a stratified lake rely on interactions of spatially and temporally varying wind force, bathymetry, density variation, and earth's rotation. These motions provide a major driving force for vertical and horizontal mixing of inorganic and organic materials, dissolved oxygen, storm water and floating debris in stratified lakes. In Lake Tahoe, located between California and Nevada, USA, basin-scale circulations are obviously important because they are directly associated with the fate of the suspended particulate materials that degrade the clarity of the lake. A three-dimensional hydrodynamic model, ELCOM, was applied to Lake Tahoe to investigate the underlying mechanisms that determine the characteristics of basin-scale circulations. Numerical experiments were designed to examine the relative effects of various mechanisms responsible for the horizontal circulations for two different seasons, summer and winter. The unique double gyre, a cyclonic northern gyre and an anti-cyclonic southern gyre, occurred during the winter cooling season when wind stress curl, stratification, and Coriolis effect were all incorporated. The horizontal structure of the upwelling and downwelling formed due to basin-scale internal waves found to be closely related to the rotating direction of each gyre. In the summer, the spatially varying wind field and the Coriolis effect caused a dominant anti-cyclonic gyre to develop in the center of the lake. In the winter, a significant wind event excited internal waves, and a persistent (2 week long) cyclonic gyre formed near the upwelling zone. Mechanism of the persistent cyclonic gyre is explained as a geostrophic circulation ensued by balancing of the baroclinc pressure gradient (or baroclinic instability) and Coriolis effect. Topographic effect, examined by simulating a flat bathymetry with constant depth of 300m, was found to be significant during the winter cooling season but not as significant as the wind curl and baroclinic effects.

• Journal of Ginseng Research
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• v.46 no.1
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• pp.23-32
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• 2022

Panax polysaccharides are biopolymers that are isolated and purified from the roots, stems, leaves, flowers, and fruits of Panax L. plants, which have attracted considerable attention because of their immunomodulatory activities. In this paper, the composition and structural characteristics of purified polysaccharides are reviewed. Moreover, the immunomodulatory activities of polysaccharides are described both in vivo and in vitro. In vitro, Panax polysaccharides exert immunomodulatory functions mainly by activating macrophages, dendritic cells, and the complement system. In vivo, Panax polysaccharides can increase the immune organ indices and stimulate lymphocytes. In addition, this paper also discusses the membrane receptors and various signalling pathways of immune cells. Panax polysaccharides have many beneficial therapeutic effects, including enhancing or activating the immune response, and may be helpful in treating cancer, sepsis, osteoporosis, and other conditions. Panax polysaccharides have the potential for use in the development of novel therapeutic agents or adjuvants with beneficial immunomodulatory properties.

• Journal of Environmental Science International
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• v.8 no.3
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• pp.337-347
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• 1999

This study was carried out to evaluate the characteristics of dissolved organics based on their origins, which were divided into two categories. The first group consisted of river, lake and secondary sewage treatment effluent, which were chosen as representative of their origins. The second group were artificial samples which were made of AHA(Aldrich humic acids) and WHA(Wako humic acids). Physicochemical characteristics, biological degradability and THMEP(trihalomethane formation potential) of the samples were analysed based on the AMWD(apparent molecular weight distribution). Large portion of dissolved organic carbon(DOC) in the river and lake samples was comprised of LMW(low molecular weight), which that of AHA and WHA was HMW(high molecular weight). The DOC of the lake was evenly distributed in the all range of molecular weight. The river, lake and secondary treated effluent have lower ultraviolet(UV) absorbance at 254nm, and have a higher amount of humic acids. Higher absorbance of humic acids means that aliphatic bond and benzenoid type components that absorb UV light were contained in these kind of humic acids. It was expected that lake sample was the most biodegradable in the different samples investigated, and in order of secondary sewage treatment effluent, river, WHA and AHA based on the result of determination of specific ultraviolet absorbance(SUVA). Biodegradability showed similar result except for AHA, while dissolved organics in the range of LMW decreased during the biodegradability test, and on the contrary those of HMW increased. Production of the SMPs(soluble micobial products) was observed during humicfication of dissolved organics and the SMPs were higher production of the SMPs. THM formation was high in the samples containing HMW and similar tendency was shown in the THMEP(trihalomethane formation potential), except for WHA.

• Journal of Korean Society on Water Environment
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• v.23 no.6
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• pp.889-896
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• 2007

From the direct outflow of Chungju Dam to the junction of water body and watershed in Paldang lake is the scope of this research. This study performed to investigate the main cause of water quality deterioration and the influenced region in the middle field range of the Namhan river Basin with the onsite measurement of water quality and flow rate simultaneously during spring dry season. The purpose of this study is to find out the time-spatial variation characteristics of water quality and flow rate. Following the flow direction $BOD_5$ and $COD_{Mn}$ concentration increased to the highest value of 3.7 mg/L, 5.9 mg/L at Wolgesa respectively. Chl.a concentration increased to $50mg/m^3$ or so at Kangsang, after that it decreased to $37mg/m^3$ at the junction of Paldang lake. Organic matter concentration variation trend showed similar than that of Chl.a. Also $BOD_5$ concentration tendency was similar to Chl.a in every measuring sites except Paldang lake mixing zone. The major factors of water quality deterioration in Namhan river and Paldang lake during dry season were algal bloom and followed internal production. High phosphorus load from Dalcheon and Seom river caused dry season algal bloom and internal production in transitional zone which was stagnant area in downstream of Namhan river.

• Journal of Korean Society on Water Environment
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• v.31 no.3
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• pp.286-294
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• 2015

Temporal and spatial characteristics of cyanobacterial communities at the monitoring stations for Harmful Algal Bloom Alert System (HABAS) in Nakdong River and Lake Dukdong were investigated for two years (2013 to 2014). A total of 30 cyanobacterial species from 14 genera were found at the survey stations. Microcystis sp. showed maximum cell density in the total cyanobacterial community in August, 2014 at ND-2 and in September, 2013 at ND-3 station. Lynbya limnetica and Geitlerinema sp., non-target species for alert criteria showed maximum cell density at ND-1 (August, 2013) and Dam station of Lake Dukdong (September, 2014), respectively. Total cyanobacterial cell density and the relative abundance of four target genera (Microcystis, Anabaena, Aphanizomenon and Oscillatoria spp.) for alert criteria was relatively lower in the mesotrophic Lake Dukdong than at the eutrophic riverine stations of Nakdong River, indicating cyanobacterial density and the RA of target genera is affected by the trophic state of the monitoring stations. Simulating the alert system using phycocyanin concentration as an alert criterion resulted in the longer period of alert issued compared to the period of alert issued using the current criterion of harmful cyanobacterial cell density due to the influence of phycocyanin concentration from non-target cyanobacterial species.

• Journal of the Korean association of regional geographers
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• v.22 no.1
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• pp.211-224
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• 2016

Natural lakes are estimated in variety with that's function or value depending on age environment or geographical characteristics. There are many kind of natural lakes, but the kind of natural lake is limited in rivers in korea flowing into East Sea. However, Yeonho lake in Uljin has different geographical characteristics with oxbow lake or lagoon which is common in korea's river flowing into East Sea. Therefore the purpose of this study is to analyze geographical characteristics due to the process of Yeonho's formation. Further more research for protecting wetland is needed to adequately preserve, depending on the geomorpologic process. To analyze geographical characteristics, it was essential to compare and analyze topographical map of 1918 1956 2012 and I pictured estinated line of bedrock and longitudinal section of Nam-dae cheon(Riv) Yeonho cheon(Riv). In addition, I denoted flooded areas through design flood level of Nam-dae cheon(Riv) Yeonho cheon(Riv) and analyzed particle size distribution of deposited sediment due to consider deposit environment. The results of study are as follows. In conclusion, Yeonho lake is floodbasin which was not researched at river flowing into East Sea. Through this study, my opinion is that floodbasin can be formed in the river that is steep and short. I argue that preservation methods will be seeked by geomorphologic process of floodbasin and development of downtown.