• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.6
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• pp.131-142
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• 2020

The objective of this study was to evaluate future inundation risk of farmland according to the application of coupled model intercomparison project phase 5 (CMIP5) and coupled model intercomparison project phase 6 (CMIP6). In this study, future weather data based on CMIP5 and CMIP6 general circulation model (GCM) were collected, and inundation was simulated using the river modeling system for small agricultural watershed (RMS) and GATE2018 in the Tanjung district of the Moohan stream watershed. Although the average probable rainfall of CMIP5 and CMIP6 did not show significant differences as a result of calculating the probability rainfall, the difference between the minimum and maximum values was significantly larger in CMIP6. The results of the flood discharge calculation and the inundation risk assessment showed similar to trends to those of probability rainfall calculations. The risk of inundation in the future period was found to increase in all sub-watersheds, and the risk of inundation has been analyzed to increase significantly, especially if CMIP6 data are used. Therefore, it is necessary to consider climate change effects by utilizing CMIP6-based future weather data when designing and reinforcing water structures in agricultural areas in the future. The results of this study are expected to be used as basic data for utilizing CMIP6-based future weather data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.349-356
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• 2021

Since the 1960s, traffic infrastructure, such as bridges, has increased rapidly in Korea as urbanization and industrialization progressed due to economic growth. As the scale of the bridge becomes larger, stability analysis of the superstructure of the bridge is being conducted actively, but scour stability analysis for the substructure of the bridge has not been conducted sufficiently. This study is a basic investigation to prevent large-scale disasters caused by scouring in bridge piers. A simple linear regression model was used to analyze the scour depth calculated through seventeen scour depth calculation formulae, and the scour depth measured through hydraulic model experiments. As a result, the Coleman (1971) formula was the best method among the scour depth calculation formulae, and the Froehlich (1987) formula was the most effective method for calculating the scour depth. In addition, a review using a simple regression model confirmed that the scour depth calculation formulae of CSU (1993), Coleman (1971), and Froehlich (1987) can predict a similar scour depth by reflecting domestic stream characteristics. This study can calculate the scour depth reflecting the environmental conditions of Korea in future stream design.

• Journal of the Korean Association of Geographic Information Studies
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• v.4 no.3
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• pp.21-30
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• 2001

This research was carried out for analyzing watershed and river topography. The method based on experience and map was mainly used, but derived data are too much to effectively analyze. Therefore some researchers have introduced computer system using GIS technique and remote sensing data. This research used GIS and remote sensing technique for classifying and analyzing watershed and river topography. Also dendrochronology method was introduced for guessing the creation times of deposits. Stream order map, sub-basin delineation map, river-bed microtopograpy were produced through this research. These results may be used in planning for Donggang conservation.

• Korean Journal of Ecology and Environment
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• v.40 no.1
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• pp.40-49
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• 2007

For effective watershed management, we must understand the complex and dynamic relationships of land uses and water quality. Despite numerous studies investigated the relationships between water quality and land use, there are increasing concerns on the geographical variation and lack of spatial integrations in previous studies. We investigated the relationships between land use and water quality characteristics in the Hwa-Sung estuarine reservoir watershed in Korea, which has spatially integrated land uses. The spatial variations of these relationships were also examined using zonal analysis. Water quality parameter were correlated positively with residential and forest and negatively with paddy and upland especially during base flow in the near buffer zone. During storm flow, correlation between land use and water quality was less apparent. Population and livestock density was correlated well to water quality parameter than just number of population and livestock. Relationships across zones, distinguished by distances from streams, were inconsistent and erratic, suggesting that the relationships between remote land uses and water quality may be affected more significantly by sub-basin characteristics than by the land use itself. The watersheds studied are mainly non-urban and their land uses are similar to typical watershed of other estuarine reservoirs, therefore, the correlation developed in this study might be helpful to manage other watersheds of estuarine reservoir. This methodology could be applied to other areas where the watershed characteristics are not significantly different from the study area.

• Journal of Broadcast Engineering
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• v.21 no.3
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• pp.357-368
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• 2016

In DAB+, HE-AAC v2 codec is applied for the fixed rate transmission of audio stream. In case that xHE-AAC codec including USAC, a more efficiency is expected when the variable frame is used in a given same bandwidth compared to the fixed frame transmission. For this to be realized, audio streams need to be multiplexed in a sub-channel before transmission, then a method is required to identify the border of each audio frames. In this paper, the toggled sync byte and additional identification field being sequentially placed between AU borders are proposed in order to deal with the AU border identification. In addition, the Reed-Solomon based error correction code which is compliant to DAB+ is proposed.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.3
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• pp.221-233
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• 2018

Two climate change scenarios, the RCP (Representative Concentration Pathways) 4.5 and the RCP 8.5 in the fifth Assessment Report (AR5) by Intergovernmental Panel on Climate Change (IPCC), were applied in the Yocheon basin area using the SWAT (Soil and Water Assessment Tool) model to estimate changes in flow rates and pollutant loadings in the future. Field stream flow rate data in Songdong station and water quality data in Yocheon-1 station between 2013~2015 were used for model calibration. While $R^2$ value of flow rate calibration was 0.85 and $R^2$ value of water qualities were in the 0.12~0.43 range. The total study period was divided into 4 sub periods as 2030s (2016~2040), 2050s (2041~2070) and 2080s (2071~2100). The predicted results of flow rates and water quality concentrations were compared with results in calibrated periods, 2015s (2013~2015). In both RCP scenarios, flow rate and TSS (Total Suspended Solid) loadings were estimated to be in increasing trend while TN (Total Nitrogen) and TP (Total Phosphorus) loadings showed decreasing patterns. Also, flow rates and pollutant loadings showed larger differences between the maximum and the minimum values in RCP 4.5 than RCP 8.5 scenarios indicating more severe effect of drought and flood, respectively. Dependent on simulation period and rainfall periods in a year, flow rate, TSS, TN and TP showed different trends in each scenario. This emphasizes importance of considerations on time and space when analyzing climate change impacts of each variable under various scenarios.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.6
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• pp.428-433
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• 2009

Dissolved oxygen is considered as one of the important water-quality constituents in streams from one century ago and fishes perish in low dissolved oxygen concentration. Environmental scientists and engineers have introduced the deterministic model to estimate dissolved oxygen concentration of streams and recommended the use of the Delta Method (DM), Approximate Delta Method (ADM), Extreme Value Method (EVM) and Optimization Method (OPT) which can be applied in no spatial variation of dissolved oxygen. The diurnal or annual variation of dissolved oxygen is mainly determined from the parameters such as reaeration rate, 1st production rate and respiration rate which are related to dissolved oxygen. Each method was briefly introduced and applied to two sampling sites of Anseong Stream watershed in this paper. The limitation, advantages and disadvantages of each method were reviewed and analyzed after running the each method. From these analyses, the benefit-cost approach to estimate dissolved oxygen effectively in streams was recommended.

• The Journal of the Korea Contents Association
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• v.14 no.3
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• pp.125-139
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• 2014

In this study, we're going to look at the formation process of Youth film Festival and factors affecting that process. The Youth film Festival didn't appear suddenly in a day. There have been various trial regarding media education by civil society organizations (NGO) until the mid 1990s, principal Youth film Festival has been held from 1997s to 2001s and established a framework for Youth film Festival. There were some progress after those times and then in 2008 Youth film Festival faced some changes such as screening online, and responded rapidly to the current image industry and the cultural stream like the appearance of HD camcoder and smart phone till now. We can divide two areas regarding factors that affecting those formation process of Youth film Festival. First, they are explained as economic and social factors that the situation of South Korea extremely such as the efforts of civil society organizations (NGO), image technology and development of the industry, IMF bailout era and so on, second cultural and educational factors that the rise of virtual culture, the University entrance and results of awards. Thus Youth film Festival has been evolved in various affects, so we can look into the various sections of korea society through these formation process of Youth film Festival.

• Journal of Ecology and Environment
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• v.38 no.2
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• pp.145-156
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• 2015

This study was based on water quality data of the Lake Doam watershed, monitored from 2010 to 2013 at eight different sites with multiple physiochemical parameters. The dataset was divided into two sub-datasets, namely, non-rainy and rainy. Principal component analysis (PCA) and factor analysis (FA) techniques were applied to evaluate seasonal correlations of water quality parameters and extract the most significant parameters influencing stream water quality. The first five principal components identified by PCA techniques explained greater than 80% of the total variance for both datasets. PCA and FA results indicated that total nitrogen, nitrate nitrogen, total phosphorus, and dissolved inorganic phosphorus were the most significant parameters under the non-rainy condition. This indicates that organic and inorganic pollutants loads in the streams can be related to discharges from point sources (domestic discharges) and non-point sources (agriculture, forest) of pollution. During the rainy period, turbidity, suspended solids, nitrate nitrogen, and dissolved inorganic phosphorus were identified as the most significant parameters. Physical parameters, suspended solids, and turbidity, are related to soil erosion and runoff from the basin. Organic and inorganic pollutants during the rainy period can be linked to decayed matters, manure, and inorganic fertilizers used in farming. Thus, the results of this study suggest that principal component analysis techniques are useful for analysis and interpretation of data and identification of pollution factors, which are valuable for understanding seasonal variations in water quality for effective management.

• Journal of the Korean Association of Geographic Information Studies
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• v.10 no.4
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• pp.22-34
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• 2007

The purpose of this study is to evaluate landscape characteristics of watersheds in the Nakdong River Basin for identifying the groups of watershed with similar landcover patterns by using Geographic Information System and statistical technique. According to the results based on the cluster analysis using cluster analysis tool in the ArcGIS 8.3 program, 22 sub-watersheds were classified into three types; "Forest watershed", "Agriculture watershed", and "Urban watershed". In the forest watershed that has the least potential of ecological disturbances by human, a forest management approach based on geographic conditions and coverage types, etc., should be developed to sustain the ecological and environmental functions of forest. For the agriculture watershed, environmental-friendly agricultural techniques should be performed in the particular enhancement of riparian buffer zone to the prevent direct inflow of soils, fertilizers, and other chemicals into the stream network. Finally, in the urban watershed, an environmental-friendly plan that may increase the ratio of pervious surface and amount of green-space to should be reserved.