• Journal of Korea Water Resources Association
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• v.38 no.11
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• pp.927-935
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• 2005

Soil erosion by rainfall is important factor for basin management because it reduces reservoir capacity and breaks out the contamination of water caused by turbid water. Recently, soil erosion study with GIS is in progress but does not consider soil erosion source area. This study calculated soil erosion amount using GIS-based soil erosion model in Imha basin and examined soil erosion source area using SPOT 5 High-resolution satellite image and land cover map. As a result of analysis, dry field showed high-density soil erosion area and we could easily investigate source area using satellite image. Also we could examine the suitability of soil erosion area by applying field survey method in common areas such as dry field and orchard area those are difficult to confirm soil erosion source area using satellite image.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.1
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• pp.111-122
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• 2014

The provided habitat of many services from natural capital is important. But because most ecosystem services tools qualitatively evaluated biodiversity or habitat quality, this study quantitatively analyzed those aspects using the species distribution model (MaxEnt). This study used location point data of the goat(Naemorhedus caudatus), marten(Martes flavigula), leopard cat(Prionailurus bengalensis), flying squirrel(Pteromys volans aluco) and otter(Lutra lutra) from the 3rd National Ecosystem Survey. Input data utilized DEM, landcover classification maps, Forest-types map and digital topographic maps. This study generated the MaxEnt model, randomly setting 70% of the presences as training data, with the remaining 30% used as test data, and ran five cross-validated replicates for each model. The threshold indicating maximum training sensitivity plus specificity was considered as a more robust approach, so this study used it to conduct the distribution into presence(1)-absence(0) predictions and totalled up a value of 5 times for uncertainty reduction. The test data's ROC curve of endangered mammals was as follows: growing down goat(0.896), otter(0.857), flying squirrel(0.738), marten(0.725), and leopard cat(0.629). This study was divided into two groups based on habitat: the first group consisted of the goat, marten, leopard cat and flying squirrel in the forest; and the second group consisted of the otter in the river. More than 60 percent of endangered mammals' distribution probability were 56.9% in the forest and 12.7% in the river. A future study is needed to conduct other species' distribution modeling exclusive of mammals and to develop a collection method of field survey data.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.152-152
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• 2021

The importance of groundwater has long been recognized, but the ground water potential to become contaminated as a result of human activities has only been recognized in recently. Before 1980 it was thought that soils served as filters, preventing harmful substances deposited at the surface from migrating into groundwater. Today it is known that soils have a finite capacity to protect groundwater. It can be contaminated from divers sources. Therefore, Assessment of aquifer vulnerability to pollution is essential for the protection and management of groundwater and land use planning. In this study, we used DRASTIC and AVI for groundwater vulnerability to contamination assessment. the different methods were applied to the southern coastal sedimentary basin of Benin and DRASTIC method was modified in two different steps. First, we modified DRASTIC by adding land use parameter to include the actual pollution sources (DRASTIC_LcLu) and second, classic DRASTIC weights was modified using Shannon's entropy (Entropy weight DRASTIC). The reliability of the applied approaches was verified using nitrate (NO3^-) concentration and by comparing the overall vulnerability maps to the previous researches in the study area and in the world. The results from validation showed that the addition of landcover/land use parameter to the classic DRASTIC helps to improve the method for better definition of the vulnerable areas in the basin and also, the weight modification using entropy improved better the method because Entropy weight DRASTIC_LcLu showed the highest correlation with nitrate concentration in the study basin. In summary the weight modification using entropy approach reduced the uncertainty of the human subjectivity in assigning weights and ratings in the standard DRASTIC.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.391-391
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• 2020

본 연구의 목적은 2006년 6월 ~ 10월에 발생한 메콩강 하류 지역의 홍수를 모의하는 것이다. 강우자료는 위성강우 자료인 미국 NOAA의 CMORPH를 적용하였으며, 홍수유출 해석은 GRM 모델을 적용하였다. Tonlesap 호수를 포함하는 메콩강 하류 지역의 침수분석은 G2D 모델을 적용하였다. 위성강우 자료는 NOAA의 3시간 간격의 CMORPH 위성강우자료를 일일강우량 자료로 변환하고, 일본의 Research Institute for Humanity and Nature (RIHN)과 Meteorological Research Institute of the Japan Meteorological Agency (MRI/JMA)의 APHRODITE 프로젝트에 의해 구축된 APHRODITE 강우량 자료를 이용하여 보정한 후 홍수모의에 적용하였다. DEM 자료는 HydroSHED 15s자료를 이용하였고, 토양도는 UN FAO의 HWSD, 그리고 토양도는 Global map landcover ver3.0을 이용하였다. GRM 모델과 G2D 모델은 Github(https://github.com/floodmodel)에 공개되어 있으며, 이를 이용하였다. 유출 모델은 메콩강 전체 유역을 대상으로 2682.815m의 공간해상도로 구축하였다. 보정한 강우를 이용하여 유출모의 한 결과 첨두유량은 23,796.8 ㎥/sec로 계산되었다. Kratie 지점의 유출량과 Tonlesap 호수로 집수되는 유량을 상류단 경계조건으로 이용하여 약 150일 동안의 침수모의를 하였다. 450 m 공간해상도로 침수모의 도매인을 구축하였으며, 조도계수는 0.045를 사용하였고, 하류단은 자유수면 유출조건을 적용하였다. 침수분석 결과 메콩강 본류를 흐르는 유량이 Tonlesap 호수로 유입되어 호수의 수위가 상승하였다. Tonlesap 호수의 최대침수심은 약 11 m를 나타내었으며, 호수로 유입된 유량은 모의기간 중에 호수에 저류되어 있었다. 메콩강 본류의 Kratie 지점으로 유입되는 유량이 첨두값을 지난 후에도 모의 기간이 길어질수록 메콩강 하류 델타지역과 그 주변의 평지로 침수범위가 확대 되었다. 모의 종료시에는 메콩강 하류가 광범위하게 침수되면서 최대 침수면적을 나타내었다. 본 연구에서 메콩강을 범람한 홍수는 메콩강 하류의 서쪽 해안으로 먼저 유출이 되었다. 이는 침수모의에 적용된 DEM 자료가 북동쪽에서 서남쪽 방향으로 빗살무늬 형태의 고도분포를 가지기 때문인 것으로 판단되며, 대상 지역의 DEM 정확성 평가와 함께 추가적인 연구가 필요하다.

• Journal of Environmental Science International
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• v.32 no.6
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• pp.429-440
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• 2023

Quantitative habitat model is established with species occurrence and spatial abundance data, which were usually acquired by professional field ecologists and citizen scientists. The importance of citizen science data is increasing, but the quality of these data needs to be evaluated. This study aims to identify and compare both expert-based data and citizen science data based on the performance power of quantitative models derived from both data sets. A Maximum Entropy (MaxENT) model was developed using eight environmental variables, including climate, topography, landcover and distance to forest edge. The AUC values derived from the MaxENT model were 0.842 and 0.809, respectively, indicating a high level of explanatory power. All environmental variables has similar values for both data sets, except for the distance to forest edge and rice paddy, which was relatively higher for expert-based survey data than that of the citizen science data as the distances increased. This result suggests that habitat model derived from expert-based survey data shows more ecological niche including wider ranges from forest edges and isolated habitat patches of rice paddy. This is presumably because citizen scientists focuses on direct observation methods, whereas professional field surveys investigate a wider variety of methods.

• Journal of The Geomorphological Association of Korea
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• v.27 no.4
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• pp.71-88
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• 2020

This study modified the properties and boundaries of the inland wetland types through the structural edit of the National Wetland DB, and analyzed the characteristics of the different land cover by area and the entire inland wetlands of South Korea. The inland wetlands of the Gangwon Basin had a small area of waters. In addition, the ratio of natural barren was high, reflecting the characteristics of the upper reaches of the large river in the east and west part of Gangwon Province. The Geum River Basin had a high percentage of aggregate land due to the development of large alluvial land, and the ratio of artistic barren was low, so various ecosystem service of wetland elements were distributed evenly. The Nakdong River Basin had a high proportion of waters as water level in the channel rose due to the installation of 4 Major Rivers Beam, and the ratio of Natural barren was low. Moreover, the water level of the main attributes flowing into the Nakdong River drainage system was not high, so the ratio of vegetation concentration was high. The Yeongsan River Basin showed that Waters had the high proportion. And the distribution of Natural barrens represented differently according to the Yeongsan River Basin and the Seomjin River Basin. Finally, Sand and Gravels supplied to rivers during precipitation were deposited in the main stream of the Han River Basin, and the differences between the side and high side was large in the area, reflecting the characteristics of the mouth of a river, so the Natural barren of Clay was distributed.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.1
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• pp.89-100
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• 2010

The aim of this study is to produce land cover maps using satellite imagery with various degrees of high resolution and then compare the accuracy of the image types and categories. For the land cover map produced on a small-scale classification the estuary area around the Nakdong river, including an urban area, farming land and waters, was selected. The images were classified by analyzing the aerial photos taken from KOMPSAT2, Quickbird and IKONOS satellites, which all have a resolution of over 1m to the naked eye. Once all of the land cover maps with different images and land cover categories had been produced they were compared to each other. Results show that image accuracy from the aerial photos and Quickbird was relatively higher than with KOMPSAT2 and IKONOS. The agreement ratio for the large-scale classification across the classification methods ranged between 0.934 and 0.956 for most cases. The Kappa value ranged between 0.905 and 0.937; the agreement ratio for the middle-scale classification was 0.888~0.913 and the Kappa value was 0.872~0.901. The agreement ratio for the small-scale classification was 0.833~0.901 and the Kappa value was 0.813~0.888. In addition, in terms of the degree of confusion occurrence across the images, there was confusion on the urbanized arid areas and empty land in the large-scale classification. For the middle-scale classification, the confusion mainly occurred on the rice paddies, fields, house cultivating area and artificial grassland. For the small-scale classification, confusion mainly occurred on natural green fields, cultivating land with facilities, tideland and the surface of the sea. The findings of this study indicate that the classification of the high resolution images with the naked eye showed an agreement ratio of over 80%, which means that it can be used in practice. The findings also suggest that the use of higher resolution images can lead to increased accuracy in classification, indicating that the time when the images are taken is important in producing land cover maps.

• Journal of the Korean Association of Geographic Information Studies
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• v.15 no.2
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• pp.86-102
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• 2012

For predictive flooded area susceptibility mapping, this study applied and verified probability model and the frequency ratio using a geographic information system (GIS) and frequency raio. Flooded areas were identified in the study area of field surveys, For predictive flooded area susceptibility mapping, this study applied and verified probability model and the frequency ratio using a geographic information system (GIS) and frequency raio. Flooded areas were identified in the study area of field surveys, and maps of the topography, geology, landcover and green infrastructure were constructed for a spatial database. The factors that influence flooded areas occurrence, such as slope gradient, slope, aspect and curvature of topography and distance from darinage, were calculated from the topographic database. Lithology and distance from fault were extracted and calculated from the geology database. The frequency ratio coefficient is overlaid for flooded areas susceptibility mapping as each factor's ratings. Then the flooded areas susceptibility map was verified and compared using the existing flooded areas. As the verification results, the frequency ratio model showed 82% in prediction accuracy. The method can be used to reduce hazards associated with flooded areas and to plan land use.

• Journal of the Korean Association of Geographic Information Studies
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• v.8 no.2
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• pp.175-185
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• 2005

Governmental authorities have been trying to develop our city in respect to the growth of economy and it is true that their developmental policies have negative effects on ecosystem without doubt. To estimate these negative effects, this study is mainly focused on analysing the usage of the land according to the urban growth, and the temporal and spatial patterns between the elements which consist of the landscape of Daegu Metropolitan Sphere, by using the GIS method and the landscape indices. The results of the this study are as follow; the urban areas widened for $193.4km^2$ due to the shift of the urban function, and the forest areas were encroached for $455.6km^2$ into other landcover patterns. It was the shift of the agriculture areas that are given the most influence in those procedures since those developmental conditions are relatively satisfactory. Moreover the forest areas are structurally fragmented into the complicated form, and also the patterns of adjacent patches are become complex. These transitions are regarded as causes of increased external interventions to the forest areas, and these could possibly deteriorate the soundness of forest areas by reducing the core areas which are habitats of species. In conclusion, the results of this study evaluate the influence of much broader urban development on environment structure around urban and mutual relationship between them. In addition, it can provide methods and basic informations for the establishment of metropolitan urban plan after due considerations of the landscape ecological principle.

• Journal of Wetlands Research
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• v.13 no.3
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• pp.443-453
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• 2011

This research aims at suggesting the mitigation measures of decreasing pollution by analyzing land cover characteristics according to subwatershed, and non-pollutant load characteristics occurring in each subwatershed. Mushim-cheon is selected as a research area, and HyGIS-SWAT is used as a water quality model. This research analyzed outflow load characteristics by classifying land cover, which has over 50% classified items, into a city area, a farmland area and a forest area. The result shows that the yearly occurrence load quantity represents a farmland area, a forest area and a city area in order. In subwatershed-2, occurrence load quantity is analyzed by setting up a buffer zone in the center of stream, and by changing a farmland area into a natural grass land. Therefore, a farmland area in a subwatershed changes 36.6% into 27.9% and 15.3% comparing to previous land cover change. In the analysis of sediment loads occurrence quantity and nutritive salt load occurrence quantity in subwatershed-2, sediment loads occurrence quantity decreases 52% to about 47%, and nutritive salt load decreases 49% and 34% in compare with previous change. Hereafter, this research will set up the mitigation measures scenario, and find out which is more effective for the mitigation measures.