• Journal of Positioning, Navigation, and Timing
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• v.10 no.1
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• pp.67-73
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• 2021

The need for precise location data is growing across numerous markets, and so is the number of affordable high-precision GPS receivers. In this paper, we validated the performance of RTAP2U, a low-cost high-precision RTK receiver that was recently released. Two positioning modes were tested: static and driving. The static test conducted Zero-Baseline Single-RTK and Network-RTK survey for 57 hours and 51 hours, respectively. For the driving test, Network-RTK survey was conducted using VRS services provided by NGII based on Trimble PIVOT and Geo++ GNSMART. The static test showed about 1 cm horizontal and vertical accuracies, which is very stable considering the test duration longer than 50 hours. The integer ambiguity FIX rate marked a solid 100%. The driving test result also reached a 100% FIX rate. Horizontal and vertical accuracies were better than 2 cm and 3 cm, respectively. Researchers can refer to this paper when considering affordable high-precision GPS receivers as an option.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.205-207
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• 2013

멀티 클라우드 서비스 제공자가 연동된 환경에서 각 데이터 센터에 위치하고 있는 물리 노드들의 위치에 따라서 클라우드 서비스 사용자와 연결된 네트워크 속도에 차이가 발생하고 이에 의해서 각 물리 노드에서 생성되는 가상 자원 인스턴스의 작업 처리 성능에도 영향을 미치게 된다. 특히 웹 어플리케이션과 같은 네트워크 성능에 의존도가 높은 응용의 경우 이에 대한 성능 영향의 정도가 매우 크게 증가한다. 본 논문에서는 이러한 문제를 해결하기 위하여 클라우드 서비스 사용자와 가상 자원 인스턴스간의 물리적인 거리 및 동적인 네트워크 상황을 고려한 적응적 가상 자원 할당 기법을 소개한다.

• Journal of the Korean GEO-environmental Society
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• v.16 no.2
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• pp.27-31
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• 2015

In urban area, many design projects related to geotechnical projects are controlled by serviceability rather than stability requirements. Accordingly, control of ground deformation has become more crucial and many researchers have studied soil stiffness. Recent experimental studies on the stress-strain response of Chicago glacial clays showed that the nonlinearity and anisotropy are the two key factors in evaluating the soil stiffness. In this study, experimental results are applied to analyze the deep excavation site locating in downtown Chicago. The stress paths observed from the observation points located behind and front of the supporting wall yield typical stress paths. Changes in soil stiffness nonlinearity and anisotropy were discussed by comparing experimental and computed stress paths. The stiffness anisotropy were significant even at the first few excavations. The stiffness degradation characteristics are significantly different according to relative location to the support wall even at the same elevation.

• Spatial Information Research
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• v.20 no.2
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• pp.129-136
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• 2012

Recently international organizations such as ISO/TC211, OGC, INSPIRE (Infrastructure for Spatial Information in Europe) make an effort to share geospatial data using semantic web technologies. In addition, smart phone and social networking services enable community-based opportunities for participants to share issues of a social phenomenon based on geographic area, and many researchers try to find a method of extracting issues from that. However, serviceable spatial ontologies are still insufficient at application level, and studies of spatial information extraction from SNS were focused on user's location finding or geocoding by text mining. Therefore, a study of extracting spatial phenomenon from social media information and converting it into geosemantic knowledge is very usable. In this paper, we propose a framework for extracting keywords from micro-blog, one of the social media services, finding their relationships using data mining technique, and converting it into spatiotemopral knowledge. The result of this study could be used for implementing a related system as a procedure and ontology model for constructing geoseem antic issue. And from this, it is expected to improve the effectiveness of finding, publishing and analysing spatial issues.

• Journal of Cadastre & Land InformatiX
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• v.45 no.2
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• pp.71-85
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• 2015

Recently, the South Korean government actively opens the public data to encourage people to use it in private sector. It is based on 'Government 3.0' that is the paradigm for government operation. According to this trend, a data platform is required for establishing and commercializing business models that utilizing geospatial data. However, it is currently insufficient to establish the geospatial data system using the text-based public open data. This study constructs a geospatial data supply system using the public data for the purpose of providing and using the public data of spatial reference type efficiently. It improves the accessibility of user and the usability to the public data having location information. Besides, this study suggests that the components of the appliance system that connects the public data from different public institutions for different purposes with producing the geospatial data in the type of a finished product.

• Journal of the Korean GEO-environmental Society
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• v.11 no.1
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• pp.27-34
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• 2010

A finite element analysis has been conducted to clarify the behaviour of a single pile in heaving ground related to ground excavation. The numerical analysis has included soil slip at the pile-soil interface, analysing the interaction between the pile and the clay has been studied. The study includes the upward movement of the pile, the relative shear displacement between the pile and the soil and the shear stresses at the interface and the axial force on the pile. In particular, the shear stress transfer mechanism at the pile-soil interface related to a decrease in the vertical soil stress has been rigorously analysed. Due to the reductions in the vertical soil stress after excavation, the relative shear displacement and the shear stress along the pile have been changed. Upward shear stress developed at most part of the pile (Z/L=0.0-0.8), while downward shear stress is mobilized near the pile tip (Z/L=0.8-1.0) resulting in tensile force on the pile, where Z is the pile location and L is the pile length. Some insights into the pile behaviour in heaving ground analysed from the numerical analyses has been reported.

• Journal of the Korean GEO-environmental Society
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• v.8 no.3
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• pp.51-57
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• 2007

In the design of slopes during rainfall, the groundwater level is assumed to be located at the ground surface, based on the change in characteristics of rainfall. In addition, stability investigations are performed for large cut slopes in the design of slopes while standard inclinations specified in the design criteria are applied for the slopes that stability investigations are not performed. In spite of the strengthened criteria of groundwater location, slope failures continuously occur during heavy rainfall, regardless of magnitude of slopes. In order to investigate the cause of the failures, stability investigations have been performed on standard inclination of slopes suggested in the design criteria for both dry and rainfall cases by ground condition in this research. Despite that standard inclination of slopes specified in the design criteria should be stable for both dry and rainfall cases, the results show that standard factor of safety has not been obtained in many cases; more than 50% of total cases for dry cases and more than 65% of total cases for rainfall case. Based on the results, this paper indicates the problems in the current design criteria and proposes the plans for establishment of countermeasure.

• Journal of the Korean GEO-environmental Society
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• v.14 no.12
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• pp.61-69
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• 2013

As construction for road and train tunnel is increasing, various geotechnical conditions can be faced during the construction stage. Especially, if the tunnel is located in limestone area, the cavity is mostly to locate in tunnel planning location. One or some cavities which can be harmful for tunnel safety are predicted. Hence, this study was fulfilled to confirm the influence between tunnel and cavity using laboratory scale down model test and numerical analysis. The scale down model test was carried out to confirm the failure load of the model ground about the interval length of cavity and tunnel and to analyze behaviour characteristics of the model ground on the cavity shape. From the model test result, the failure load decrease in accordance with decreasing of interval length between cavity and tunnel within 0.5D. The numerical analyses were carried out for verification about scale down model test. From the numerical analysis result, tunnel safety decreases in the case of the interval between cavity and tunnel within 0.5D.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.8
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• pp.3374-3383
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• 2011

In this study, numerical analyses for slamming impact phenomena have been carried out using a 2-dimensional wedge shaped structure having finite deadrise angles. Fluid is assumed incompressible and entry speed of the structure is kept constant. Geo-reconstruct(or PLIC-VOF) scheme is used for the tracking of the deforming free surface. Numerical analyses are carried out for the deadrise angles of $10^{\circ}$, $20^{\circ}$ and $30^{\circ}$. For each deadrise angle, variations are made for the grid size on the wedge bottom and for the entry speed. The magnitude and the location of impact pressure and the total drag force, which is the summation of pressure distributed at the bottom of the structure, are analyzed. Results of the analyses are compared with the results of the Dobrovol'skaya similarity solutions, the asymptotic solution based on the Wagner method and the solution of Boundary Element Method(BEM).

• Journal of the Korean GEO-environmental Society
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• v.15 no.11
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• pp.5-12
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• 2014

A slope may fail after construction owing to external factors such as localized rainfall, earthquake, and weathering. Therefore, the grasp of failure probability for slope failures is necessary to maintain their stability. In particular, it is very difficult to detect the symptoms of rock slope failure in advance by using traditional methods, such as displacement due to the brittleness of rocks. However, Acoustic Emission (AE) techniques can predict slope failures earlier than the traditional methods. This study grasped failure probability of slope by applying AE techniques to a rock slope with a history of collapse. When applying AE techniques to a slope that has a high probability of failure, the grasp of failure probability of the specific location became possible.