• Journal of Korea Water Resources Association
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• v.42 no.1
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• pp.21-31
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• 2009

The characteristics, intensity and direction of groundwater.surface water interactions are controlled by groundwater head gradients, hydraulic conductivity and by the riverbed geometry. As a result of the spatial heterogeneity of these factors and the subsequent variability of the impact of these interaction processes, the water balance is also characterized by highly variable spatial patterns and temporal dynamics. However, spatially detailed studies concerning the spatio-temporal variability of the extent and intensity of surface-groundwater interactions have been limited to the investigation of cross-sections or small stream reaches. Thus, the extensive study on the watershed based interaction between surface water and groundwater is to be analyzed. In this study, the intensity and the spatial extent of interactions along the stream were found by using integrated SWAT-MODFLOW model. This integrated modeling approach was applied to Anyangcheon watershed in Korea. The effluent stream characteristics were found in the watershed, namely, baseflow was annually discharged except heavy rainy periods. The intensity and the spatial extent of surface-groundwater interactions in different sub-watersheds were found on a daily basis. The influential extent of surface-groundwater interaction become larger as the watershed elevations are lower.

• Journal of the Korean association of regional geographers
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• v.16 no.6
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• pp.706-723
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• 2010

The impervious surface was frequently employed as a proxy of the total environmental burden in the urban area. The impervious surface was extracted from a satellite image and the GIS (Geographical Information System) database for childhood asthma hospitalizations was generated for a total of 62,136 children using the National Health Insurance database of South Korea. Children living in an impervious environment do result in almost twice as many hospitalizations (26.58%) for asthma, as compared to the sub-urban pervious living (15.82%). Furthermore, the risk zones with persistently high hospitalizations for three years were specifically identified over the impervious sub-district alone. The impervious zone showed a small inter-year variation of hospitalizations (r: 0.937) while the sub-urban pervious fringe was found to display a yearly variation(r: 0.371). The strong temporal autocorrelation means that the impervious areas have frequent long-lived hospitalizations for asthma, thus children living in impervious areas were likely to have had more chronic asthma attacks than those living in pervious areas. These experimental results indicate that an impervious surface as thematic parameter of analysis is a crucial explanatory variable for asthma hospitalizations and its longer persistence among children.

• Journal of Korea Water Resources Association
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• v.43 no.7
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• pp.667-679
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• 2010

The distributed hydrologic model has been considerably improved due to rapid development of computer hardware technology as well as the increased accessibility and the applicability of hydro-geologic information using GIS. It has been acknowledged that physically-based distributed hydrologic model require significant amounts of data for their calibration, so its application at ungauged catchments is very limited. In this regard, this study was intended to develop a distributed hydrologic model (S-RAT) that is mainly based on conceptually grid-based water balance model. The proposed model shows advantages as a new distributed rainfall-runoff model in terms of their simplicity and model performance. Another advantage of the proposed model is to effectively assess spatio-temporal variation for the entire runoff process. In addition, S-RAT does not rely on any commercial GIS pre-processing tools because a built-in GIS pre-processing module was developed and included in the model. Through the application to the two pilot basins, it was found that S-RAT model has temporal and spatial transferability of parameters and also S-RAT model can be effectively used as a radar data-driven rainfall-runoff model.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.4
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• pp.221-230
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• 2017

Demographic change was considered to be the most major driver of land use change although there were several interacting factors involved, especially in the developing countries. This paper presents an approach to predict the future land use change using a hybrid model. A hybrid model consisting of logistic regression model, Markov chain (MC), and cellular automata (CA) was designed to improve the performance of the standard logistic regression model. Experiment was conducted in Giao Thuy district, Nam Dinh Province, Vietnam. Demography and socio-economic variables dealing with urban sprawl were used to create a probability surface of spatio-temporal states of built-up land use for the years 2009, 2019, and 2029. The predicted land use maps for the years 2019 and 2029 show substantial urban development in the area, much of which are located in areas sensitive to source protections. It also showed that aquacultural land changes substantially in areas where are in the vicinity of estuary or near the sea dike. There was considerable variation between the communes; notably, communes with higher household density and higher proportion of people in working age have larger increases in aquacultural areas. The results of the analysis can provide valuable information for local planners and policy makers, assisting their efforts in constructing alternative sustainable urban development schemes and environmental management strategies.

• The Journal of Engineering Geology
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• v.28 no.1
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• pp.35-45
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• 2018

Imaging technologies are applied at various geological scales including pore scale, core scale and intermediate scale in order to characterize pore space of rocks as well as to map the fluid distribution in porous media. This technical report presents experimental results using core-flooding apparatus suited with imaging technology. Three different core samples, that are homogeneous, fractured and heterogeneous cores, were used to assess the two-phase fluid migration behavior as $CO_2$ displaces resident brine. We show that imaging technology can be effective in characterizing salt-precipitation, capillary pressure and spatio-temporal variation of trapping mechanisms.

• Journal of Korea Water Resources Association
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• v.44 no.8
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• pp.683-694
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• 2011

To analyze the regional impact of air temperature increase and precipitation variation on water resources, the variability of precipitation-effectiveness (P-E) ratio which is estimated using precipitation and air temperature data of 59 weather stations operated by the Korean Meteorological Administration (KMA) during 1973~2009 was analyzed. Also runoff data resulting from the Precipitation-Runoff Modelling System (PRMS) modelling were analyzed during 1966~2007. The overall spatio-temporal variability of P-E ratio and runoff data in South Korea is corresponding to the variability of precipitation amount. However some region shows that the P-E ratio decreases even though the trend of precipitation amount increases which may be caused by the air temperature increase. Runoff trend is similar to that of P-E ratio. Precipitation and P-E ratio have decreased all seasons except summer season and it means the reduction of available water resources during those seasons. These variability should be reflected in the spring, fall, and winter water supply strategy.

• Atmosphere
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• v.27 no.3
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• pp.301-316
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• 2017

This study analyzes the spatio-temporal variability of terrestrial carbon flux and the response of land carbon sink with climate factors to improve of understanding of the variability of land-atmosphere carbon exchanges accurately. The coupled carbon-climate models of CMIP5 (the fifth phase of the Coupled Model Intercomparison Project) and CT (CarbonTracker) are used. The CMIP5 multi-model ensemble mean overestimated the NEP (Net Ecosystem Production) compares to CT and GCP (Global Carbon Project) estimates over the period 2001~2012. Variation of NEP in the CMIP5 ensemble mean is similar to CT, but a couple of models which have fire module without nitrogen cycle module strongly simulate carbon sink in the Africa, Southeast Asia, South America, and some areas of the United States. Result in comparison with climate factor, the NEP is highly affected by temperature and solar radiation in both of CT and CMIP5. Partial correlation between temperature and NEP indicates that the temperature is affecting NEP positively at higher than mid-latitudes in the Northern Hemisphere, but opposite correlation represents at other latitudes in CT and most CMIP5 models. The CMIP5 models except for few models show positive correlation with precipitation at $30^{\circ}N{\sim}90^{\circ}N$, but higher percentage of negative correlation represented at $60^{\circ}S{\sim}30^{\circ}N$ compare to CT. For each season, the correlation between temperature (solar radiation) and NEP in the CMIP5 ensemble mean is similar to that of CT, but overestimated.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.spc1
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• pp.180-188
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• 2006

We examined the effect of salt marsh vegetation on the benthic environment in macro-tidal flats at Donggeomdo, Ganghwa, on the west coast of Korea. Nine stations were established along a transect across the tidal flats, including salt marsh, and field sampling was conducted monthly from July 1997 to June 1998. During the study period, environmental parameters fluctuated as follows: salinity, 15.0 to 28.2 psu, exposure time, 613 to 702 hr/m, inundation time, 28 to 117 hr/m, sediment organic carbon, 0.71 to 1.34%, nitrogen, 0.07 to 0.16%, sulfur from 0.07 to 0.22%, mean grain size from 6.3 to $6.9{\phi}$, water content from 19.4 to 44.4%, water temperature from 4.4 to $20.4^{\circ}C$ and temperature of the surface sediments, 2.7 to $31.1^{\circ}C$, in total, seven halophyte species were sampled and found to be vertically distributed across the tidal levels. Carer scabrifolia, Suaeda maritima, Limonium tetragonum and Phragmites communis dominated the upper zone of the salt marsh, Juncus haenkei, Triglochin maritimum and P. communis dominated the middle zone, and Suaeda japonica predominated in the lower area. Principal component analysis (PCA) and non-metric multi-dimensional scaling revealed that the zonation of halophytes was related to environmental variables such as salinity and exposure time. The halophyte communities were likely related to the organic content of the surface sediment.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.3
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• pp.164-179
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• 2001

Spatio-temporal variation in species composition, abundance and distribution of fisheries resources caught by large purse seine off Korea from 1991 to 1994 was analysed. Out of 19 species, Scomber japonicus (54.7%), Sardinops melanostictus (20.4%), Trachurus japonicus (9.1%), and Scomberomorus niphonius (6.2%) were predominated in catch. These 4 pelagic fishes occupied 90% of total catch. Major pelagic fishes caught by large purse seine were dispersed to northward from spring to summer, and migrated to the southern wintering ground during winter. Fishing effort (number of haul) was high in summer, but catch per unit effort showed a peak in winter. The high CPUE in winter seemed to be related to aggregation of the pelagic fish to the wintering ground in the southern sea. After spawning, they were widely dispersed for feeding in warm months.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.188-195
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• 2018

Time series analysis was conducted to identify the factors affecting short-term variation of water temperature in Wando. Spectrum analysis showed that air temperature peaks at diurnal period, while water temperature and tide level peak at both semi-diurnal and diurnal periods. Coherence between water temperature and the tide level presented 0.92 at semi-diurnal period. Numerical experiment were carried out to understand the spatio-temporal distribution of water temperature in the study area. Average water temperature difference between maximum ebb and flood was $0.3^{\circ}C$ in spring tide, but $0.13^{\circ}C$ in neap tide. The reason for the large difference in spring tide is that relatively cold water entered with strong tidal currents at flood tide and flowed out at ebb tide. Water temperature on coasts was higher than out at sea. This is because the depth in the coast is shallower than at sea, and water temperature increases rapidly due to solar radiation.