• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.6 no.2
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• pp.120-128
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• 2003

Purpose: Recently, while the authors were experiencing that the epidemic period of rotaviral infection happened more in the early spring, we tried to find out how the outbreaks of rotaviral infection are changing in detail depending on the weather condition since it has something to do with the climate factors and PM10. Methods: Fourteen hundreds seventy nine patients who were proved to be positive to rotavirus were chosen among children less than 5 years old from January 1995 to June 2003. Among various climate factors, monthly average temperature, humidity, rainfall and PM10 were selected. Results: Rotaviral infection was most active in 2002 as 309 (20.9%) patients. It has been the spring that is the most active period of rotaviral infection since 2000. The temperature (RR=0.9423, CI=0.933424~0.951163), rainfall (RR=1.0024, CI=1.001523~1.003228) and PM10 (RR=1.0123, CI=1.009385~1.015248) were significantly associated with the monthly distribution of rotaviral infection. Conclusion: Through this study we determined that the epidemic period of rotaviral infection is changed to spring, which is different from the usual seasonal periods such as late fall or winter as reported in previous articles. As increased PM10 which could give serious influence to the human body, and changing pattern of climate factors such as monthly average temperature and rainfall have something to do with the rotaviral infection, we suppose that further study concerning this result is required in the aspects of epidemiology, biology and atmospheric science.

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.29-45
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• 2017

This study explored spatiotemporal variability of water quality in correspondence with hydro-meteorological factors in the four stations of Euiam Reservoir located in the upstream region of the North-Han River from May 2012 to December 2015. Seasonal effect was apparent in the variation of water temperature, DO, electric conductivity and TSS during the study period. Stratification in the water column was observed in the near dam site every year and vanished between August and October. Increase of nitrogen nutrients was observed when inflowing discharge was low, while phosphorus increase was distinct both during the early season with increase of inflowing discharge and the period of severe draught persistent. Duration persisting high concentration of Chl-a (>$25mg\;m^{-3}$: the eutrophic status criterion, OECD, 1982) was 1~2 months of the whole year in 2014~2015, while it was almost 4 months in 2013. Water quality of Euiam Reservoir appeared to be affected basically by geomorphology and source of pollutants, such as longitudinally linked instream islands and Aggregate Island, inflowing urban stream, and wastewater treatment plant discharge. While inflowing discharge from the dams upstream and outflow pattern causing water level change seem to largely govern the variability of water quality in this particular system. In the process of spatiotemporal water quality change, factors related to climate (e.g. flood, typhoon, abruptly high rainfall, scorching heat of summer), hydrology (amount of flow and water level) might be attributed to water pulse, dilution, backflow, uptake, and sedimentation. This study showed that change of water quality in Euiam Reservoir was very dynamic and suggested that its effect could be delivered to downstream (Cheongpyeong and Paldang Reservoirs) through year-round discharge for hydropower generation.

• Korean Journal of Ecology and Environment
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• v.36 no.2 s.103
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• pp.124-138
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• 2003

This paper aimed to analyze the relationship between alga3 bloom patterns and hydrological, limnological data which were collected from major reservoirs in Korea for 8 years (1990${\sim}$1997). Water temperature of river-type reservoirs showed wider seasonal fluctuations than that of lake-type. pH of lake-type reservoirs was low in winter season but high in summer season. In contrast, river-type reservoirs showed high pH in spring and autumn seasons as well, and very low in summer season. COD of lake-type reservoirs and Paldang reservoir was lower (2${\sim}$3 mg/L) than that of Geumgang and Nagdonggang reservoirs (6${\sim}$9 mg/L). Dissolved oxygen (DO) of river-type reservoirs was higher than that of lake-type reservoirs. Seasonal fluctuation pattern of DO saturation in river-type reservoirs was high (80 ${\sim}$100%) and remained relatively constant whereas lake-type reservoirs showed the highest level (93%) in late spring or early summer, which gradually decreased entering winter season(46${\sim}$06%). And monthly variation of DO saturation showed inverse proportion to water volume in lake-type reservoirs. Nutrients concentration in river-type lake is higher than lake-type. Seasonal fluctuation of nutrients (T-N, T-P) in lake-type reservoirs was relatively small than that of river-type reservoirs. Annual mean N/P mass ratio of lake-type reservoirs was higher than that of river-type. Transparency tended to related with the suspended solid concentration in river-type reservoirs. Algal bloom of lake-type and river-type reservoirs occurred at any time except rainfall and winter periods. And it dominated in summer and early autumn, respectively. Algal bloom of river-type reservoirs was higher than that of lake-type. Relationship between rainfall and chlorophyll- a in lake-type reservoirs was relatively high, however river-type reservoirs showed insignificant.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.3
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• pp.188-202
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• 2011

Due to emissions of greenhouse gases caused by increased use of fossil fuels, the climate change has been detected and this phenomenon would affect even larger changes in temperature and precipitation of South Korea. Especially, the increase of temperature by climate change can affect the amount and pattern of snowfall. Accordingly, we tried to predict future snowfall and the snowfall pattern changes by using the downscaled GCM (general circulation model) scenarios. Causes of snow varies greatly, but the information provided by GCM are maximum / minimum temperature, rainfall, solar radiation. In this study, the possibility of snow was focused on correlation between minimum temperatures and future precipitation. First, we collected the newest fresh snow depth offered by KMA (Korea meteorological administration), then we estimate the temperature of snow falling conditions. These estimated temperature conditions were distributed spatially and regionally by IDW (Inverse Distance Weight) interpolation. Finally, the distributed temperature conditions (or boundaries) were applied to GCM, and the future snowfall was predicted. The results showed a wide range of variation for each scenario. Our models predict that snowfall will decrease in the study region. This may be caused by global warming. Temperature rise caused by global warming highlights the effectiveness of these mechanisms that concerned with the temporal and spatial changes in snow, and would affect the spring water resources.

• Journal of the Korean earth science society
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• v.36 no.4
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• pp.315-329
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• 2015

We investigated the characteristics of meteorological conditions related to the strong downslope wind over the leeward side of the Taebaek Mountains during the period 2005~2010. The days showing the strong wind exceeding $14ms^{-1}$ in Gangwon province were selected as study cases. A total of 15 days of strong wind were observed at Sokcho, Gangneung, Donghae, and Taebaek located over the Yeongdong region. Seven cases related to tropical cyclone (3 cases) and heavy snowfall (2 cases) and heavy rainfall (2 cases) over the Yeongdong region were excluded. To investigate the characteristics of the remaining 8 cases, we used synoptic weather chart, Sokcho radiosonde, Gangneung wind profiler and numerical model. The cases showed no precipitation (or ${\leq}1mm\;day^{-1}$). From the surface and upper level weather chart, we found the pressure distribution of southern high and northern low pattern over the Korean peninsula and warm ridge over the Yeongdong region. Inversion layer (or stable layer) and warm ridge with strong wind were located in about 1~3 km (925~700 hPa) over mountains. The Regional Data Assimilation and Prediction System (RDAPS) indicated that warm core and temperature ridge with horizontal temperature gradient were $0.10{\sim}0.23^{\circ}C\;km^{-1}$ which were located on 850 hPa pressure level above mountaintop. These results were summarized as a forecasting guidance of downslope windstorm in the Yeongdong region.

• Korean Journal of Ecology and Environment
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• v.45 no.3
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• pp.278-288
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• 2012

The zooplankton community of Lake Paldang, Korea, was investigated on a weekly basis from 2004 to 2006. The seasonal succession of zooplankton community structure was influenced by hydrological factors such as rainfall pattern and efflux in Lake Paldang. According to the monsoon climate, spring, fall and winter had reduced precipitation, so that zooplankton dynamics of the lake showed a typical succession pattern. In spring, small sized and faster growing rotifera rapidly increased, and copepods and cladocera noticeably increased thereafter. Rotifera dominated the zooplankton community, occupying more than 90% of total zooplankton abundance. Among rotifera, Keratella cochlearis was extremely dominant in spring. Copepoda were mainly present as Copepodid and Nauplius. Among cladoceran species, Bosmina longirostris was dominant. In summer, during the rainy season, zooplankton were flushed out by an associated dam. After the rainy season, rotifera increased rapidly when the water column of the lake was stable. During the fall, zooplankton abundance gradually reduced in accordance with decreasing water temperature. However, the occupation rate of copepod (Copepodid, Nauplius) increased relatively. Zooplankton dynamics were influenced by meteorological changes and hydraulic-hydrological factors, because Lake Paldang is a completely closed ecosystem.

• Korean Journal of Microbiology
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• v.32 no.3
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• pp.238-244
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• 1994

To investigate the bacterial potentials for utilizing dissolved organic matter in highly eutrophic estuary, the annual fluctuations of microbiological and physicochemical environmental parameters were analyzed in Naktong River Estuary. Total bacterial number ranged from 0.33 to $2.09{\times}10^7$ cells/ml, and correlated with the heterotrophic bacterial numbers in more eutrophic sites, especially. Bacterial biovolume and biomass varied between 0.064 and 0.156 2.09${\mu}m^3$/cell, 0.163 and 1.036 ${\mu}g$-C/ml, respectively. Bacterial secondary productivity ranged from 0.24 to 60.86 ${\mu}g$-C/l/h, and showed high correlations with the environmental parameters of pollution indicator. The seasonal variation pattern of bacterial productivity in freshwater sites was high in winter and low in summer, which was interpreted as the results of pollution loads varied with the amount of rainfall. In seawater site, the pattern was different from those of freshwater sites; high in summer and low in winter. In this site, the values of bacterial productivity showed positive correaltions with chlorophyll a, heterotrophic bacterial number, and temperature (r>0.5, p<0.05). These results suggested that the main source of organic matter which influences the bacterial productivity may be allochthonous materials in the upper freshwater zone of Naktong River Barrage, and autochthonous algal excretory products in the lower seawater zone of Naktong River Barrage.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.4
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• pp.97-107
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• 2017

This study is to determine the coefficients of regression equations and to select the optimal regression equation in the LOADEST model after classifying the whole study period into 5 flow conditions for 16 watersheds located in the Nakdonggang waterbody. The optimized coefficients of regression equations were derived using the gradient descent method as a learning method in Tensorflow which is the engine of machine-learning method. In South Korea, the variability of streamflow is relatively high, and rainfall is concentrated in summer that can significantly affect the characteristic analysis of pollutant loads. Thus, unlike the previous application of the LOADEST model (adjusting whole study period), the study period was classified into 5 flow conditions to estimate the optimized coefficients and regression equations in the LOADEST model. As shown in the results, the equation #9 which has 7 coefficients related to flow and seasonal characteristics was selected for each flow condition in the study watersheds. When compared the simulated load (SS) to observed load, the simulation showed a similar pattern to the observation for the high flow condition due to the flow parameters related to precipitation directly. On the other hand, although the simulated load showed a similar pattern to observation in several watersheds, most of study watersheds showed large differences for the low flow conditions. This is because the pollutant load during low flow conditions might be significantly affected by baseflow or point-source pollutant load. Thus, based on the results of this study, it can be found that to estimate the continuous pollutant load properly the regression equations need to be determined with proper coefficients based on various flow conditions in watersheds. Furthermore, the machine-learning method can be useful to estimate the coefficients of regression equations in the LOADEST model.

• Korean Journal of Environmental Biology
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• v.32 no.4
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• pp.389-394
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• 2014

This study was conducted to find out the soil $CO_2$ emission characteristic due to rain fall pattern and intensity changes. Using Automatic Opening and Closing Chambers (AOCCs), we have measured annual soil respiration changes in Pinus koraiensis plantation at Seoul National University experimental forest in Mt. Taehwa. In addition, we have monitored heterotrophic respiration at trenching sites ($4{\times}6m$). Based on the one year data of soil respiration and heterotrophic respiration, we observed that 24% of soil respiration was derived from root respiration. During the rainy season (end of July to September), soil respiration at trenching site and trenching with rainfall interception site were measure during portable soil respiration analyzer (GMP343, Vaisala, Helsinki, Finland). Surprisingly, even after days of continuous heavy rain, soil water content did not exceed 20%. Based on this observation, we suggest that the maximum water holding capacity is about 20%, and relatively lower soil water contents during the dry season affect the vital degree of trees and soil microbe. As for soil respiration under different rain intensity, it was increased about 14.4% under 10 mm precipitation. But the high-intensity rain condition, such as more than 10 mm precipitation, caused the decrease of soil respiration up to 25.5%. Taken together, this study suggests that the pattern of soil respiration can be regulated by not only soil temperature but also due to the rain fall intensity.

• Journal of Korea Water Resources Association
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• v.48 no.6
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• pp.463-477
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• 2015

The recent unusual climate and extreme weather events have frequently given unexpected disaster and damages, facing difficulties in the management of water resources. In particular, climate change could result in intensified typhoons, and this would be the worst case scenario that can happen. The primary objective of this study is to identify the patterns of typhoon-induced precipitation and the associated synoptic pattern. This study focused on analyzing precipitation patterns over the South Korea using historic records as opposed to a specified season or duration, and further investigates the potential connection with heavy rainfall to synoptic patterns. In this study, we used the best track data provided by the Regional Specialized Meteorological Center of Japan for 40 years from 1973 to 2012. The patterns of the typhoon-induced precipitation were categorized into four groups according to a given typhoon track information, and then the associated synoptic climatology patterns were further investigated. The results demonstrate that the typhoon-induced precipitation patterns could be grouped and potentially simulated according to the identified synoptic patterns. Our future work will focus on developing a short-term forecasting model of typhoon-induced precipitation considering the identified climate patterns as inputs.