• Journal of the Korean Geotechnical Society
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• v.30 no.7
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• pp.5-15
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• 2014

Abandoned mine deposits are exposed to various physico-chemical geo-environmental hazards and disasters, such as acid mine drainage, water contamination, erosion, and landslides. This paper presents the ring shear characteristics of waste materials. The ring shear box with a rotatable O-ring was used in this study. Three tests were performed: (i) Shear stress-time relationship for given normal stress and shear speed, (ii) shear stress as a function of shear speed, and (iii) shear stress as a function of normal stress. For a given normal stress (50 kPa) and speed (0.1 mm/sec), the materials tested exhibit a strain softening behavior, regardless of drainage condition. The peak and residual shear stresses were determined for each normal stress and shear speed. The shear stress was measured when shear speed is equal to 0.01, 0.1, 1, 10, 50, 100 mm/sec or when normal stress is equal to 20, 40, 60, 80, 100, 150 kPa. From the test results, we found that the shear stress increases with increasing shear speed. The shear stress also increases with increasing normal stress. However, different types of shearing mode were observed in drained and undrained conditions. Under drained condition, particle crushing was observed from the shearing zone to the bottom of lower ring. Under undrained condition, particle crushing was observed only at the shearing zone, which has approximately 1 cm thick. It means that a significant high shear speed under undrained condition can result in increased landslide hazard.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.1
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• pp.1-9
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• 2020

ABL (Airborne Bathymetric LiDAR) is an advanced survey technology that uses green lasers to simultaneously measure the water depths and oceanic topography in coastal and river areas. Seabed point cloud extraction is an essential prerequisite to further utilizing the ABL data for various geographic data processing and applications. Conventional seabed detection approaches often use return waveforms. However, their limited accessibility often limits the broad use of the bathymetric LiDAR (Light Detection And Ranging) data. Further, it is often questioned if the waveform-based seabed extraction is reliable enough to extract seabed. Therefore, there is a high demand to extract seabed from the point cloud using other sources of information, such as geometric information. This study aimed to assess the feasibility of a ground filtering method to seabed extraction from geo-referenced point cloud data by using CSF (Cloth Simulation Filtering) method. We conducted a preliminary experiment with the RIGEL VQ 880 bathymetric data, and the results show that the CSF algorithm can be effectively applied to the seabed point segmentation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.2D
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• pp.267-274
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• 2011

In this study, around Jeju area where climatic change is most considerably appearing in Han Peninsula, we prepared sea level rise height caused by sea level rise (Seogwipo 5.6 mm/yr, Jeju 5.3 mm/yr) and a sea level rise scenario for the case when an enlarged typhoon attacks during high water ordinary spring tide, and evaluated flooding area and effect on road and facility using Digital Elevation Model(DEM) and GIS Spatial Analysis Technique. As a result, the flooding areas were shown to be 2.9 $km^2$ in 2040, 5.4 $km^2$ in 2070, and maximum 5.4 $km^2$ in 2100. Analyzing the effect of flooding on each type of road, the local roads(Gun-do) were shown to be mostly affected. The most flood effected facilities were individual houses. Especially, as there is a possibility for casualties to occur due to disaster in Hwabuk-dong because the effect of flooding on individual houses in this area was shown to be high. In addition, flood on port facilities will considerably affect logistic and marine activities. This study is thought to be a basic data which can be utilized for establishment of strategic coping measures and policies of government affiliated organizations through analysis of effect of sea level rise on construction field.

• Journal of Environmental Policy
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• v.13 no.2
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• pp.3-20
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• 2014

Due to habitat damage associated with climate change and human activities, biodiversity has decreased all over the world. In order to prevent further reduction in biodiversity, the international community has endeavored to establish a cooperative system, such as the Convention on Biological Diversity (CBD). Until now, most biodiversity strategic planning has been led by the national government. However, the National Biodiversity Strategy and Action Plan is conservative and its strategic plan is vague. Therefore, we propose a method for managing local biological resources called the Local Biodiversity Strategy and Action Plan. In order to provide the strategic plans and detailed plans for the Local Biodiversity Strategy and Action Plan, the report has examined several cases including Convention on Biological Diversity, Strategic Plan for Biodiversity 2011-2020, and the biodiversity strategies and action plans of the Republic of Korea and several other countries. As a result, the report demonstrates the survey and protection of bio-species, the designation and monitoring of conservation region, the management of the integrated eco-network, the establishment of biodiversity organizations and capacity building, the methods to promote networking and traditional knowledge, and the strategy for development in bioindustry. Consequently, the implementation of biodiversity management strategies by local governments will play a significant role in preserving and increasing biodiversity by realizing the goals of Strategic Plan for Biodiversity 2011-2020.

• Journal of the Korean association of regional geographers
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• v.12 no.4
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• pp.475-495
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• 2006

This paper is to analyse a changing space of energy flows in Northeast Asia from geopolitical and geoeconomic perspectives that have been recently promoted for energy security of countries in this region. The research is based on an analytical framework in an integration of political ecology and political economy. Because of an ever-increasing input of energy resources for economic growth and of dramatically increasing price of crude oil and recent instability of oil market, South Korea, China and Japan have been deeply concerned with energy security and conducted very actively geopolitical strategies. And hence the space of energy flows in the region is now in a process of dynamic reconfiguration, in which the project for development of oil and natural gas fields in East Siberia and construction of pipelines to transport them can be seen as one of competitive issues among these countries. In spite of worrying about stagflation due to rapid increase of oil price, such geo-strategies for energy security and reconfiguration of space of energy flows seem to keep the accumulation of capital in this region continue with generation of huge privatized oil companies.

• The Journal of Engineering Geology
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• v.16 no.2 s.48
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• pp.125-134
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• 2006

In order to establish the in-situ application of the artificial storage and recovery (ASR) technology which is used the property of the aquifer storage of groundwater. We carried out to the in-situ experiments such as borehole TV logging, pumping test and artificial hydraulic fracturing in volcanic island, Ulleungdo. In-situ experiments were conducted to divide the before- and after-hydraulic fracturing. Pumping test was achieved to confirm the two fracture zones, GL-13m and GL-21m, which are determined by the borehole TV logging. From the results of the before- and after-pumping tests, the hydraulic connectivity was confirmed to locate at GL-13m in the residual deposit zone of pumice media as alluvium. However, in the bedrock tone at GL-21m the hydraulic connectivity could be considered to faulty. Consequently, in this study area the artificial recharge has a little unsatisfied to geo-structural condition and desired to more detail investigation works.

• The Journal of Engineering Geology
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• v.29 no.3
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• pp.251-264
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• 2019

The displacement monitoring of unstable block at the rock slope located in the Cheonbuldong valley of Seoraksan National Park was carried out using Terrestrial LiDAR. The rock slopes around Guimyeonam and Oryeon waterfall where rockfall has occurred or is expected to occur are selected as the monitoring section. The displacement monitoring of unstable block at the rock slope in the selected area was performed 5 times for about 7 months using Terrestrial LiDAR. As a result of analyzing the displacement based on the Terrestrial LiDAR scanning, the error of displacement was highly influenced by the interpolation of the obstruction section and the difference of plants growth. To minimize the external influences causing the error, the displacement of unstable block should be detected at the real scanning point. As the result of analyzing the displacement of unstable rock at the rock slope using the Terrestrial LiDAR data, the amount of displacement was very small. Because the amount of displacement was less than the range of error, it was difficult to judge the actual displacement occurred. Meanwhile, it is important to select a section without vegetation to monitor the precise displacement of unstable rock at the rock slope using Terrestrial LiDAR. Also, the PointCloud removal and the mesh model analysis in a vegetation section were the most important work to secure reliability of data.

• The Journal of Engineering Geology
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• v.29 no.1
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• pp.23-35
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• 2019

Landslides occur due to heavy rainfall in the summer season. Some of water may infiltrate into the ground; it causes a high saturation condition capable of causing a landslide. Soil properties are crucial in estimating slope stability and debris flow occurrence. The main study areas are Gwanaksan, Suraksan and Bukhansan (Mountain) in Seoul. A total of 44 soil samples were taken from the study area; and a series of geotechnical tests were performed. Physical and mechanical properties were obtained and compared based on region. As a result, among well-graded soils, they are classified as a clayey sand. Coarse-grained and fine-grained contents are approximately 95% and 5%, respectively, with very low amount of clay content. Density, liquid limit and dry unit weight are ranged in $2.62{\sim}2.67g/cm^3$, 27.93~38.15% and $1.092{\sim}1.814g/cm^3$. Cohesion and internal friction angle are 4 kPa and $35^{\circ}$ regardless of mountain area. Coefficient of permeability is varied between $3.07{\times}10^{-3}{\sim}4.61{\times}10^{-2}cm/sec$; it means that it results in great seepage. Permeability is inversely proportional to the uniformity coefficient and is proportional to the effective particle size. In the formal case, there was a difference by mountain area, while in the latter, the tendency was almost similar.

• The Journal of Engineering Geology
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• v.29 no.1
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• pp.13-21
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• 2019

The rainfall intensity-duration curve (I-D curve) was used for selecting the dredging time of sediments behind a debris barrier which is located at the study area in Inje-gun, Kangwon Province. The I-D curve was newly suggested by using the data of rainfall-induced landslides for about 30 years from June to September in Kangwon Province. According to the monitoring results, the landslides have been not occurred during the monitoring period of the dredged sediments management system at the study area, and also all of the rainfall events were located below the I-D curve. The weight of the dredged sediments measured at the management system in the field was increased but the weight increment was small. It means that the increase of the dredged sediments was not the effect of landslide but the effect of soil erosion at the ground surface due to heavy rainfall. The weight of the dredged sediments behind a debris barrier could be known in real time using the rainfall data measured at the management system. Also, when the I-D curve is used with the management system, it is possible to select the optimum dredging time for sediments behind debris barrier.

• Journal of The Geomorphological Association of Korea
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• v.19 no.3
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• pp.143-151
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• 2012

The tsunami disasters and tectonic movements derived from mega-earthquake(M 9.0) which occured in the sea floor of the Pacific side of northeast Japan in March, 2011 were investigated. Landward invasion limit of the tsunami was 4.0km from the present coastline in Sendai coastal plain. It was observed that sandy deposit was dristributed largely in coastward part and muddy deposit was distributed largely in landward part. The ratios of distribution distances of the above two deposits were, respectively, 60~75% and 25~40% of the whole invasion distance of the 2011 tsunami. The ratios of the above distribution distances of tsunami deposits could be used to estimate landward invasion distances of the past maga-tsunamies(e.g. '2,000year B.P. Mega-Tsunami' and 'Jogan Tsunami' etc.) in Sendai coastal plain. The mega-scale tsunami disasters were caused by the low and flat geomorphic condition in the Sendai coastal plain and the increasing effect of tsunami height affected by narrow inlet condition of the so-called Ria's coast in the Sanriku coastal area respectively. Tectonic subsidences caused by the mega-earthquake in march, 2011 were observed in many areas of Ishinomaki, Ogawa, Ogachi and Onagawa coasts in northeast Japan. The displacements of tectonic subsidence were between 0.5 meters and 1.0 meters.