• Journal of Positioning, Navigation, and Timing
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• v.10 no.4
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• pp.371-377
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• 2021

This research proposes the best combination of tropospheric delay models for Korean Positioning System (KPS). The overall results are based on real observation data of Japanese Quasi-Zenith satellite system (QZSS), whose constellation is similar to the proposed constellation of KPS. The tropospheric delay models are constructed as the combinations of three types of zenith path delay (ZPD) models and four types of mapping functions (MFs). Two sets of International GNSS Service (IGS) stations with the same receiver are considered. Comparison of observation residuals reveals that the ZPD models are more influential to the measurement model rather than MFs, and that the best tropospheric delay model is the combination of GPT3 with 5 degrees grid and Vienna Mapping Function 1 (VMF1). While the bias of observation residual depends on the receivers, it still remains to be further analyzed.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.3
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• pp.171-180
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• 2016

Earthquake event keeps increasing every year, and the recent cases of earthquake hazards invoke the necessity of seismic study in Korea, as geotechnical earthquake hazards, such as strong ground motion, liquefaction and landslides, are a significant threat to structures in industrial hub areas including coastal facilities. In this study, systemized framework of integrated assessment of earthquake-induced geotechnical hazard was established using advanced geospatial database. And a visible simulation of the framework was specifically conducted at two coastal facility areas in Incheon. First, the geospatial-grid information in the 3D domain were constructed with geostatistical interpolation method composed of multiple geospatial coverage mapping and 3D integration of geo-layer construction considering spatial outliers and geotechnical uncertainty. Second, the behavior of site-specific seismic responses were assessed by incorporating the depth to bedrock, mean shear wave velocity of the upper 30 m, and characteristic site period based on the geospatial-grid. Third, the normalized correlations between rock-outcrop accelerations and the maximum accelerations of each grid were determined considering the site-specific seismic response characteristics. Fourth, the potential damage due to liquefaction was estimated by combining the geospatial-grid and accelerations correlation grid based on the simplified liquefaction potential index evaluation method.

• The Journal of Korea Robotics Society
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• v.18 no.4
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• pp.487-495
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• 2023

This paper presents a method for autonomous exploration of indoor environments using a 2-dimensional Light Detection And Ranging (LiDAR) scanner. The proposed frontier-based exploration method considers navigability from the current robot position to extracted frontier targets. An approach to constructing the point cloud grid map that accurately reflects the occupancy probability of glass obstacles is proposed, enabling identification of safe frontier grids on the safety grid map calculated from the point cloud grid map. Navigability, indicating whether the robot can successfully navigate to each frontier target, is calculated by applying the skeletonization-informed rapidly exploring random tree algorithm to the safety grid map. While conventional exploration approaches have focused on frontier detection and target position/direction decision, the proposed method discusses a safe navigation approach for the overall exploration process until the completion of mapping. Real-world experiments have been conducted to verify that the proposed method leads the robot to avoid glass obstacles and safely navigate the entire environment, constructing the point cloud map and calculating the navigability with low computing time deviation.

• Journal of Mechanical Science and Technology
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• v.16 no.3
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• pp.302-309
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• 2002

This paper presents a technique for localization of a mobile robot using sonar sensors. Localization is the continual provision of knowledges of position that are deduced from its a priori position estimation. The environment of a robot is modeled by a two-dimensional grid map. We define a physically based sonar sensor model and employ an extended Kalman filter to estimate positions of the robot. Since the approach does not rely on an exact geometric model of an object, it is very simple and offers sufficient generality such that integration with concurrent mapping and localizing can be achieved without major modifications. The performance and simplicity of the approach are demonstrated with the results produced by sets of experiments using a mobile robot equipped with sonar sensors.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.2 no.5
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• pp.239-252
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• 2008

To facilitate the processes of e-learning resource description, discovery and reuse, e-learning objects should be appropriately described and classified using standard metadata that need to be published in a registry to reduce duplication of effort and enhance semantic interoperability. This paper describes how standard ebXML registries can be used for semantic grid computing for annotating, storing, discovering and retrieving e-learning object metadata. For semantic annotation of e-learning objects, IEEE Learning Object Metadata (LOM) is adopted as the metadata ontology. In order to support the e-learning metadata ontology in interoperable ebXML registries, a mapping scheme between LOM and ebXML Registry Information Model (RIM) is proposed. The usefulness of sharing e-learning object metadata is demonstrated by prototyping a semantic registry based on the scheme.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.06a
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• pp.171-182
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• 1998

An automated surface-strain measuring system using the image processing technique is developed in the present study, which consists of the hardware to capture and to display digital images, and the software to calculate the 3D informations of grid points from two views. New or improved algorithms the mapping and establishing correspondence of grid points and elements, the camera calibration, and the subpixel measurement of grid points, are implemented. As an application of the present system the surface-strains of deformed blanks in the limitting dome height test, the square cup deep-drawing and punch stretching to obtain the forming limit diagram are measured. The results are compared with those obtained by conventional manual methods.

• Transactions of Materials Processing
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• v.7 no.6
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• pp.575-585
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• 1998

An automated surface-strain measuring system using the image processing technique is developed in the present study which consists of the hardware to capture and to display digital images. and the software to calculate the 3-D informations of grid points from two views. New or improved algorithms for the mapping and establishing correspondence of grid points and elements the camera calibration and the subpixel measurement of grid points are implemented. As an application of the present system the surface-strains of deformed blanks in the limitting dome height test the square cup deep-drawing and punch stretching to obtain the forming limit diagram are measured. The results are com-pared with those obtained by conventional manual methods.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.16 no.1
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• pp.67-74
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• 1998

This paper performed terrain analysis using DTM(digital terrain model) with TIN/ GRID structure on PC environment. Contour layer from 1:5,000 scale map was used to produce DTM. DTHs were produced with and without considering breakline for each data structure. Processing time, file size, mean elevation and standard variation were analyzed for each DTM. slope map, aspect map were analyzed for grid structure with consideration of TEX>$5\times{5m},\;l0\times{10m},\;15\times{15m},\;l0\times{30m},\;45\times{45m},\;60\times{60m}$ cell size respectively. The results suggest following; The incorporation of breakline does improve mapping accuracy for highly disturbed landscape, Mean elevation doesn't increase as the grid size increases, while processing time, storage room is significantly lessened. Thus, the optimal grid size must be determined in advance for efficient application. slope decreases, while aspect increases as grid size is increasing.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.4
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• pp.88-94
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• 2004

Recently, vehicle simulators are widely used to evaluate driver's responses and driver assistance systems. It needs much effort to construct the virtual driving environment for a vehicle simulator. In this study, it is described how to make effectively the roads and the driving environment for a vehicle simulator. The GIS (Geographic Information System) is used to construct the roads and the environment effectively. Because the GIS is the integrated system of geographical data, it contains useful data to make virtual driving environment. First, the outline and centerline of roads is abstracted from the GIS. From the road outline, the road width is calculated. Using the centerline, the grid model of roads is constructed. The final graphic model of roads is constructed by mapping road image to the grid model according to the number of lanes and the kind of surface. Data of buildings from the GIS are abstracted. Each shape and height of buildings is determined according to kind of buildings, the final graphic model of buildings is constructed. Then, the graphic model of roadside tree is also constructed. Finally, the driving environment for driving simulator is constructed by converting the three graphic models with the graphic format of Direct-X and by joining the three graphic models.

• Journal of English Language & Literature
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• v.57 no.4
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• pp.553-580
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• 2011

This article addresses how the British Empire administered the discipline of space in nineteenth century Ireland. Space control is a part of modern disciplinary practices. I approach this issue in light of the two modern mapping of space: the geometric mapping of space and the Romantic mapping of space. The former, as seen in map-making, is characterized by imposing a standardized, stratified grid on space by eliminating local characteristics of nature. On the other hand, the latter, as shown in picturesque landscaping, aims to balance a close-up observation of nature and a far-sighted view of it, with the result of creating an ironic tension of local diversity and perspectival totality. These modern disciplinary projects of space repeat themselves in the British management of the colonized Irish territory. As the British conquer other lands, they put to good use both geometric and Romantic disciplinary methods of space. Supervising the Ordnance Survey of Ireland from 1824 to 1846, Thomas Frederick Colby, British Director of Ordnance Survey, made a mathematically strict and scientific mapping of Ireland as a scale of six inches to one mile. Parallelled to this geometric colonization of space, the Romantic colonization of space is efficiently used for the Empire's management of Ireland as well. British tourists and pro-unionist Anglo-Irish landed gentries transform it into the nature of picturesque beauty; Ireland's wild boglands turn aesthetically into desolate but beautiful scenery. Picturesque landscape in England is reborn as an aesthetics of desolation in Ireland.