• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5B
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• pp.481-488
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• 2006

This paper suggests a novel approach of integrating the quasi-distributed watershed model SWAT with the fully-distributed groundwater model MODFLOW. Since the SWAT model has semi distributed features, its groundwater components hardly considers distributed parameters such as hydraulic conductivity and storage coefficient. Generating a detailed representation of groundwater recharge, head distribution and pumping rate is equally difficult. To solve these problems, the method of exchanging the characteristics of the hydrologic response units (HRUs) in SWAT with cells in MODFLOW by fully combined manner is proposed. The linkage is completed by considering the interaction between the stream network and the aquifer to reflect boundary flow. This approach is provisionally applied to Gyungancheon basin in Korea. The application demonstrates a combined model which enables an interaction between saturated zones and channel reaches. This interaction plays an essential role in the runoff generation in the Gyungancheon basin. The comprehensive results show a wide applicability of the model which represents the temporal-spatial groundwater head distribution and recharge.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.3
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• pp.263-274
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• 2020

In the Southeast Sea of Korea, a cold water mass is formed intensively in summer every year, causing frequent abnormal sea conditions. In order to analyze the spatial changes of sea surface temperature distribution in this area, ocean fields buoy data observed at Gori and Jeongja and reanalyzed sea surface temperature(SST) data from GHRSST Level 4 were used from June to September 2018. The buoy data were used to analyze the time-series water temperature changes at two stations, and the GHRSST data were used to calculate the daily SST variance and weighted mean center(WMC) across the study area. When the buoy's water temperature was lowered, the variance of SST in the study area trend to increase, but it did not appear consistently for the entire period. This is because GHRSST is a reanalysis data that does not reflect sensitive changes in water temperature along the coast. As such, there is a limit to grasping the local small-scale water temperature change in the coast or detecting the location and extent of the cold water zone only by the statistical variance representing the SST change in the entire sea area. Therefore, as a result of using WMC to quantitatively determine the spatial location of the cold water mass, when the cold water zone occurred, WMC was located in the northwest sea area from the mean center(MC) of the study area. This means that it is possible to quantitatively identify where and to what extent the distribution of cold surface water temperature appears through SST's WMC location information, and we could see the possibility of WMC's use in detecting the scale of cold water zones and the extent of regional spread in the future.

• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.3
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• pp.93-101
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• 2017

The distribution of inter-annual variation in temperature would help evaluate the likelihood of a climatic risk and assess suitable zones of crops under climate change. In this study, we evaluated two methods to estimate the standard deviation of temperature in the areas where weather information is limited. We calculated the monthly standard deviation of temperature by collecting temperature at 0600 and 1500 local standard time from 10 automated weather stations (AWS). These weather stations were installed in the range of 8 to 1,073m above sea level within a mountainous catchment for 2011-2015. The observed values were compared with estimates, which were calculated using a geospatial correction scheme to derive the site-specific temperature. Those estimates explained 88 and 86% of the temperature variations at 0600 and 1500 LST, respectively. However, it often underestimated the temperatures. In the spring and fall, it tended to had different variance (e.g., increasing or decreasing pattern) from lower to higher elevation with the observed values. A regression analysis was also conducted to quantify the relationship between the standard deviation in temperature and the topography. The regression equation explained a relatively large variation of the monthly standard deviation when lapse-rate corrected temperature, basic topographical variables (e.g., slope, and aspect) and topographical variables related to temperature (e.g., thermal belt, cold air drainage, and brightness index) were used. The coefficient of determination for the regression analysis ranged between 0.46 and 0.98. It was expected that the regression model could account for 70% of the spatial variation of the standard deviation when the monthly standard deviation was predicted by using the minimum-maximum effective range of topographical variables for the area.

• Journal of the Korean association of regional geographers
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• v.22 no.3
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• pp.628-642
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• 2016

In small countries such as Korea, rapid expansion of cities has been pointed out as the main cause of urban and environmental issues. In order to understand the urban problems caused by urban sprawl and prepare countermeasures for it, urban sprawl must be accurately measured first of all. The purpose of this study is to analyze the spatio-temporal changes of urban sprawl process in Seoul Metropolitan Area using landscape indices which measure the degree of urban sprawl in terms of urban structure such as area, distribution, and shape of urbanized area. FRAGSTATS, which is a tool for landscape analysis, is utilized to calculate landscape indices. Major findings are as follows. First, the urban sprawl in Seoul Metropolitan Area has been continually intensified since the late 1980s and this tendency was more clearer in the 1990s than the 2000s. While leapfrog development is relatively prominent in the 1990s, infilling development is remarkable in the 2000s. Second, the progress and development types of sprawl progress were different according to the zones which are defined based on Seoul Metropolitan Area Readjustment Planning Act. Congestion Restrain Zone shows the highest level of urban sprawl in terms of the evaluated landscape indices, but infilling development was predominant. In Growth Management Zone1, leapfrog development was dominant in the 1990s and infilling development in the 2000s. In Growth Management Zone1, leapfrog development has been continually remarkable since the late 1980s. Nature Conservation Zone shows the lowest level of sprawl, but its sprawl tendency is gradually being intensified. Third, the sprawl tendency in Seoul Metropolitan Area was different according to the distance and direction from Seoul. Urban sprawl was remarkable at Si-Guns close to Seoul in the late 1980s, Si-Guns close to Seoul and the southern part of Seoul in the late 1990s, and the southern and northern parts of Seoul in the late 2000s.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.3
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• pp.211-224
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• 2006

It was analysed that spatial and temporal change patterns of COD, TN and TP were measured monthly from 2002 to 2005 in Jumunjin Harbour. Cenerally, concentration of upper layer higher than lower layer, concentration difference of COD, TN and TP on upper lower layer at inner zone in Jumunjin Harbour higher than sea area front of breakwater. Seasonal change width of COD concentration different, but seasonal change pattern of COD, $NH_{4}-N$ and TN clearly showed. Water quality improvement effect of seawater exchange facilities and sewage treatment plants is analysed quantitatively using averaged spatial and temporal data set. Change of COD small at 2003, concentration reduced about $34{\sim}47%$ at all zones on 2004 and 2005. TN was influenced largely effect of seawater exchange facilities. Concentration reduction at zone 1, 2, 3 estimated about $60{\sim}70%,\;40{\sim}60%,\;40%$, respectively. As a consequence, concentration reduction of COD and TN that is, effect of water quality improvement influenced seawater exchange facilities appeared not only at inner zone, also sea area front of breakwater and entrance of Jumunjin Harbour.

• Journal of the Korean Regional Science Association
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• v.35 no.3
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• pp.7-23
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• 2019

Smart cities are expanding their spatial scope to urban areas and regions. Linking regional economic development strategies beyond the borders with smart city planning can lead to cooperation and economic development between regions and countries as well. The purpose of this study is to suggest cooperation and regional development of the three nations - Korea, North Korea and China - through the Yellow Sea Rim Smart Region. To this end, smart city strategies and economic development plan with implementation status in the three countries including special economic zones have analyzed that could be the spatial basis of the smart region. On the west coast of Korea facing the Yellow Sea, lots of projects related to smart cities are actively underway in Saemangeum, Yellow Sea Free Economic Zone(YESFEZ), and Incheon Free Economic Zone(IFEZ). Although the political situation is still uncertain, North Korea is analyzed to have economic and technical potential in the west coast connecting Haeju, Nampo, and Sinuiju. In Liaoning and Shandong provinces of China, smart city projects have been actively promoted in recent years especially in the state-supporting industrial cities. Restoration of economic cooperation between South Korea and China, linkage of transportation networks, vitalization of cross-border cooperation projects between China and North Korea centered on Dandong and Sinuiju, and the connecting of smart city infrastructure and services for China and South Korea's economic cooperation process will make the Yellow Sea Rim as a world prosperous economic region. However, it is necessary to establish and operate a governance system through long-term planning for transnational consultation and establishment of a promotion organization.

• Journal of Korea Water Resources Association
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• v.39 no.7 s.168
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• pp.605-615
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• 2006

In order to analyze movement of soil moisture, Time Domain Reflectometry(TDR) with multiplex system has been installed at the Bumreunsa hillslope of Sulmachun Watershed to configure spatial-temporal variation pattern considering seasonal characteristic. An intensive surveying was performed to build a refined digital elevation model(DEM) and flow determination algorithms with inverse surveying have been applied to establish an efficient soil moisture monitoring system. Soil moisture data were collected through an intensive and long term monitoring 380 hrs in November of 2003 and 1037 hrs in May and June of 2004. Soil moisture data shows corresponding variation characteristics of soil moisture on the up slope, buffer, main channel zones of the hillslope which were classified from terrain analysis. Measured soil moisture data were discussed in conjunction with flow characteristic through terrain analysis. Regardless season, immediate responses of soil moisture about rainfall looks similar but recession and recharge are primary characteristics of intermediate soil moisture variation for spring to summer and fall to winter season, respectively.

• Journal of Cadastre & Land InformatiX
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• v.48 no.1
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• pp.201-213
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• 2018

In recent years, the number of traffic accidents caused by car accidents has been decreasing steadily due to traffic accident prevention activities in Korea. However, the number of accidents in Seoul is higher than that of other regions. Various studies have been conducted to prevent traffic accidents, which are human disasters. In particular, previous studies have performed the spatial analysis of traffic accidents by counting the number of traffic accidents by administrative districts or by estimating the density through kernel density method in order to identify the traffic accident cluster areas. However, since traffic accidents take place along the road, it would be more meaningful to investigate them concentrated on the road network. In this study, traffic accidents were assigned to the nearest road network in two ways and analyzed by hotspot analysis using Getis-Ord Gi* statistics. One of them was investigated with a fixed road link of 10m unit, and the other by computing the average traffic accidents per unit length per road section. As a result by the first method, it was possible to identify the specific road sections where traffic accidents are concentrated. On the other hand, the results by the second method showed that the traffic accident concentrated areas are extensible depending on the characteristic of the road links. The methods proposed here provide different approaches for visualizing the traffic accidents and thus, make it possible to identify those sections clearly that need improvement as for the traffic environment.

• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.3
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• pp.82-92
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• 2006

As beaches throughout Korea have suffered great losses of sand due to artificial developments and meteorological phenomena, particularly typhoons, it is necessary to monitor beaches that are prone to erosion continuously, establish and enforce a comprehensive plan to attack coastal erosion with the object of the long-term management. However, debates and temporary measures, not based on accurate coastal zone surveys and analyses, have been established up to now. Therefore, with Haeundae sand beach as a case study, we proposed methods to collect accurate spatial data of the coastline and the sand beach through GPS survey. And we detected and analyzed topographic changes resulting from Typhoon Nabi quantitatively and qualitatively, by using GIS technique. Results showed a mean elevation of 1.95 m, a total area of 53,441 $m^2$, and a total volume of 104,639 $m^3$ after Typhoon Nabi. Mean elevation rose 0.06 m between the pre- and the post-typhoon surveys by a protective shore wall. However, strong winds and north-northeast surges brought by the typhoon caused erosion of the area and the volume, by 3,096 $m^2$ and 2,320 $m^3$. Accurate spatial databases of coastal zones based on integrated GPS GIS techniques and quantitative and qualitative analyses of topographical changes will help Korea develop systematic and effective countermeasures against coastal erosion.

• Journal of Korea Spatial Information System Society
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• v.9 no.3
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• pp.35-50
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• 2007

In a data centric sensor network, a sensor node to store data is determined by the measured data value of each sensor node. Therefore, if the same data occur frequently, the energy of the sensor node to store the data is exhausted quickly due to the concentration of loads. And if the sensor network is extended, the communication cost for storing data and processing queries is increased, since the length of the routing path for them is usually in the distance. However, the existing researches that generally focus on the efficient management of data storing can not solve these problems efficiently. In this paper, we propose a NUNS(Non-Uniform Network Split) method that can distribute loads of sensor nodes and decrease the communication cost caused by the sensor network extension. By dividing the sensor network into non-uniform partitions that have the minimum difference in the number of sensor nodes and the splitted area size and storing the data which is occurred in a partition at the sensor nodes within the partition, the NUNS can distribute loads of sensor nodes and decrease the communication cost efficiently. In addition, by dividing each partition into non-uniform zones that have the minimum difference in the splitted area size as many as the number of the sensor nodes in the partition and allocating each of them as the processing area of each sensor node, the NUNS can protect a specific sensor node from the load concentration and decrease the unnecessary routing cost.