• Journal of the Korean Society of Environmental Restoration Technology
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• v.20 no.6
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• pp.107-115
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• 2017

This study illustrated the process of bar structure and vegetation coverage to understand historical changes of riverbed and suppose adaptive management in Tan-chun ecological landscape reserve. The study site that lower reach of the Tan-chun are known as habitats of migratory bird and aquatic species with dynamic riverbed. Aerial photos from 2006 to 2016 and surveyed vegetation data in 2006 and 2016 were used by analysis of landscape changes and comparison of vegetation coverage. Study area is classified into 3 sites (A: straight site, B: meandering site, C: meandering and junction with Yangjae-cheon). The result showed that bar area of A and C sites gradually increased, B site decreased during 10 years. Also, ratio of bar area to vegetation coverage and level of vegetation coverage increased in all sites during 10 years. All sites seem to have experienced the terrestrialization with time. On the other hand, ratio of annual vegetation increased and ratio of perennial vegetation decreased in C site in 2016 compare to 2006. Because area of Japanese Hops (Humulus japonicas) as one type of annual vegetation increased, other vegetation could not grow up by its powerful expandability. It is time to make active adaptive management based on not only continuos monitoring but also revaluation of river conditions in order to enhance habitat quality and quantity in Tan-chun ecological landscape reserve.

• Journal of the Korean association of regional geographers
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• v.10 no.2
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• pp.341-355
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• 2004

This thesis is to analyze characteristic of sustainable development in the Nak-dong River. The results are summarized in the followings. 1) The principles which did not consider the equilibrium between development and environment, ecosystem, security. precautionary measure, equity could devise a plan, changes of economic land area, sand & gravel extractions from the riverbed, the river contamination cleanup, dam build 2) The rules which disregard polluter pay and opening participation in public affairs could input of too much province budget and manpower, project team. The measures to solve these problems could be proposed expansion of environmental infrastructure, sustainable sand & gravel extractions from the riverbed, fortifying the assistance of the residents who live in Dam construction site and the peripheral area of Dam, lower local fund rates in national projects, and the creation of management organization.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.437-441
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• 2009

The modern times is as special as from the river, the river is very important of our life. The importance to preserve the river environment has been issued and the river developing method is being changed to use potential function of nature as well as flood control. Essential element of the river restoration is a vegetation. The flow resistance by vegetation along the river banks is greatly increase the flood stage. Therefore, the flow resistance due to vegetation in the river and roughness coefficient changes to understand the hydraulic characteristics is an important elements in the river restoration. The purpose of this study is to analyze the flood stage and the aspects of riverbed changes due to the corridor restoration with river vegetation. In order to simulate the flood stage and riverbed changes, HEC-RAS, RMA-2, and SED-2D model were applied for the upstream and downstream in study reaches, respectively.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.1
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• pp.65-74
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• 1985

This study is an experimental analysis for local scour of the riverbed at pier. The basic equation with dimensionless elements(Pier Reynolds Number, Dimensionless Turbulence Intensity) is derived through dimensional analysis. After testing the goodness of fit of data, the coefficients are determined by multiple regression analysis. In the region where the value of the attack angle is near 20 degrees, there exists a transition region where the slope of equation with Pier Reynolds Number changes from positive to negative and that of equation with Dimensionless Turbulence Intensity changes from negative to positive adversely. As a result of testing the equation suggested on this study by using the data of the Institute of National Construction, it is found that the scour depth and width at pier can be predicted approximately.

• The Journal of Engineering Geology
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• v.22 no.3
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• pp.263-274
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• 2012

We performed numerical modeling to estimate the groundwater level around a riverside area following the construction of an artificial structure. The groundwater level of the alluvial deposit responded more rapidly to the river water level than to the rainfall event itself, indicating that the groundwater and river water are directly interrelated through the riverbed. Furthermore, transient modeling showed raised groundwater levels at the southern part of Mt. Dok and the eastern part of Mt. Dummit in an area of low plains. The artificial structure caused a rise in groundwater level of up to approximately 6 m.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2006.11a
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• pp.33-45
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• 2006

The interest of sediment has been increased daily because most of domestic dam reservoir's operation time have been extended and wide basin area is the main characteristics for artificial reservoir which the speed of water flow in artificial reservoir is slower than that of natural reservoir. Therefore a lot of sediment has been significantly accumulated. In this study, the accurate topographic data were obtained using echo-sounding system. GPS survey, low-frequency sub-bottom profiler, and high-frequency echo-sounding system were used to compute the exact amount of sediment. Based on the results, DEM(Digital Elevation Model) and DSM(Digital Surface Model) were generated. The GIS system for the management of sediment was created based on topographic data on the riverbed and this system can be efficiently used for the management of sediment which caused the problems of reservoir capacity and water quality.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.34 no.2
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• pp.153-159
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• 2016

Rivers refer to either natural or artificial structures whose primary functions are flood control and water conservation. Due to recent localized torrential downpours led by climate change, large amounts of eroded soil have been carried away, forming deposits downstream, which in turn degrades the capacity to fulfill these functions. To manage rivers more effectively, we need data on riverbed erosion and deposition. However, environmental factors make it challenging to take measurements in rivers, and data errors tend to prevent researchers from grasping the current state of erosions and deposits. In this context, the aim of the present study is to provide basic data required for river management. To this end, the author made annual measurements with a Real-time Kinematic-Global Positioning System (RTK-GPS) and a total station in Pats Cabin Canyon, Oregon, United States, and also prepared thematic maps of erosion and deposition thickness as well as water depth profiles based on a GIS spatial analysis. Furthermore, the author statistically analyzed the accuracy of three dimensional (3D) measurement points and only used the data that falls within two standard deviations (i.e. ±2σ). In addition, the author determined a threshold for a DEM of Difference (DoD) by installing measurement points in the rivers and taking measurements, and then estimated erosion and deposition thickness within a confidence interval of ±0.1m. Based on the results, the author established reliable data on river depth profiles and thematic maps of erosion and deposition thickness using pre-determined work flows. It is anticipated that the riverbed data can be utilized for effective river management.

• Journal of The Geomorphological Association of Korea
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• v.24 no.2
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• pp.27-40
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• 2017

This study tries to analyze topographic distribution and characteristics of as well as formative age and incision rate of fluvial terraces in Danyang River on western side and Geum River on eastern side of the northern Sobaek Mountains and to estimate geomorphic development during the late Quaternary in the mountains regarded as one of the uplift axes in the Korean Peninsula. OSL age dating shows that the fluvial terrace I with an altitude above riverbed of approximately 7~13 m in Danyang River has a formative age of approximately 18 ka (MIS 2) and incision rate in the river is approximately 0.156~0.194 m/ka based on the age. Altitudes above riverbed of the fluvial terrace I in Geum River range from approximately 7 to 14 m and the terrace is thought to be older than 70 ka based on age result from aeolian sediments above the terrace deposits, suggestive of an incision rate less than approximately 0.10 m/ka. These results indicate lower uplift rate in the northern Sobaek Mountains than in the Taebaek Mountains. Moreover, it can be suggested that the northern Sobaek Mountains has experienced asymmetric uplift during the late Quaternary, because the river on western side of the northern Sobaek Mountains shows greater uplift rate than the eastern side river does. Low incision rate in Geum River can be attributed to low altitude of the river basin with little difference in altitude from the base level as well as to gentle river slope due to influence of Nakdong River.

• Journal of The Geomorphological Association of Korea
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• v.19 no.1
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• pp.29-40
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• 2012

The sand dunes at the lower reach of the Duman river indicate that their distribution patterns and directions conform to the dominant northwestern winter wind. On the riverbed of the Duman river at the surroundings of sand dunes form sandy point bars and mid-stream islands. The geomorphic processes of sand dunes can be classified into two types according to the depositional environments via analyses of the sand grain size and stratigraphic profiles. First, the sand dunes of Hoelyongbong, Kyeongshin-Wonjeong, and the riverside areas of the Duman river, have formed by alluvium of the Duman river which deposits and accumulates on the riverbed, then being wind blown to the nearby sand bars, terraces and higher eroded hills. The second type is the active sand dune of the Bangcheon-Nodongja District which develops similarly as to the formation of the first type, but the fixed sand dunes of the district seem to have formed in the underwater condition.

• Journal of the Korea Society for Simulation
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• v.28 no.2
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• pp.97-105
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• 2019

The tactical mobile ad-hoc network(MANET) consists of distributed autonomous networks between individual ground nodes, which is effective in terms of network survivability and flexibility. However, due to constraints such as limited power, terrain, and mobility, frequent link disconnection and shadow area may occur in communication. On the other hand, the satellite network has the advantage of providing a wide-area wireless link overcoming terrain and mobility, but has limited bandwidth and high-latency characteristic. In the future battlefield, an integrated network architecture for interworking multi-layer networks through a heterogeneous network gateway (HNG) is required to overcome the limitations of the existing individual networks and increase reliability and efficiency of communication. In this paper, we propose a new HNG architecture and detailed algorithm that integrates satellite network and the tactical MANET and enables reliable data transfer based on flow characteristics of traffic. The simulations validated the proposed architecture using Riverbed Modeler, a network-level simulator.