• Journal of Wetlands Research
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• v.16 no.3
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• pp.327-336
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• 2014

Submerged thin walls are extreme case of submerged rectangular blocks, and could be used for many purposes in rivers or coastal zones, e.g. to tsunami. To understand flow characteristics including flow and pressure fields around a specific submerged thin wall a numerical model was applied which includes computation of hydrodynamic pressure on ${\sigma}$-coordinate. ${\sigma}$-coordinate has strong merits for simulation of subcritical flow over mild-sloped beds. On the other hand ${\sigma}$-coordinate is quite poor to treat sharp structures on the bed. There have been a few trials to incorporate dynamic pressure in ${\sigma}$-coordinate by some researchers. One of the previous approaches includes process of sloving the Poisson equation. However, the above method includes many high-order terms, and requires long cpu for simulation. Another method SOLA was developed by Hirt et al. for computation of dynamic pressure, but it was valid for straight grid system only. Previous SOLA was modified for ${\sigma}$-coordinate for the present purpose and was adopted in a model system, CST3D. Computed flow field shows reasonable behaviour including vorticity is much stronger than the upstream and downstream of the structure. The model was verified to laboratory experiments at a 2DV flume. Time-average flow vectors were measured by using one-dimensional electro-magnetic velocimeter. Computed flow field agrees well with the measured flow field within 10 % error from the speed point of view at 5 profiles. It is thought that the modified SOLA scheme is useful for ${\sigma}$-coordinate system.

• Journal of Advanced Navigation Technology
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• v.18 no.6
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• pp.555-561
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• 2014

Data processing service via internet help user to get the GNSS data processing result more precise and easily. Thus, online data process system is operated and developed by various research groups and national. But this service is difficult to use in domestic cadastral survey. In this study, we developed the online data processing system for a domestic cadastral survey. This is calculated coordinate using NGII CORS(SUWN) fiducially. And use PPP technique by GIPSY-OASIS. If user choose the observation data which want to calculate the coordinate, then is uploaded to GIPSY-OASIS server through FTP. After upload is complete, server automatically calculate coordinate, and send the report about result using e-mail. And it takes 2 minutes runtime on the basis of the 3 sessions. To verify the result, we used the data on SOUL, JUNJ as compared with notified-coordinate from NGII. As a result, got the difference for east-west 1.4 cm, north-south -1.0 cm, vertical 0.5 cm.

• Journal of Korean Society for Geospatial Information Science
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• v.8 no.1 s.15
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• pp.111-120
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• 2000

A cadastral map that is base map on Land Information System is divided by two categories, graphical and digital cadastre. And digital cadastre can be displayed with location coordinates of nodes that depict parcel boundary on digital cadastral records. The transformation of digital cadastral records means that imported text data of node coordinate would be transformed into system data. This study was implemented to search reasons of errors resulted from transformation of graphic data and then to analyze the accuracy in terms of Position and area. For this, checking of software used in Geo-Spatial Information System was implemented at first and it was found that the accuracy is up by using double precision in coordinate transformation. On the position accuracy the errors at nodes was erased during making topology and the errors did not effect other nodes. On the area may the area errors because of being in error limit of allowable area had no problems in using of system.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.7
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• pp.718-723
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• 2014

In this paper, we developed the inspection system of electric vehicle battery plate using image processing. Four cameras are used for acquiring the principal parts of the plate, and several steps of image processing for extracting significant dimensions of the plate such as widths and lengths. As a preceding step, calibration of four cameras is carried for compensating distorted images using dot-arrayed sheet. Coordinate systems for four cameras are defined where one coordinate system is assigned to the reference coordinate system to which the others are relatively described. Line information of the edge in the windowed image is extracted using elaborate edge-detection algorithm, and finally the intersection points between lines are extracted to calculate widths and lengths of the plate from which the error status of the battery plate is decided.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.2
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• pp.281-286
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• 2017

SNS is a platformwhere users build a social relationship and share opinions and informations. To do these, it supports a text, an image and a video data. As it is possible to exploit the location data of a smart device, SNS tries to use the location data. However,since SNS does not support the coordinate data, it provides the restricted function sharing the image map instead of the vector map. In this paper, we propose a chatting systemsharing pathsto support the coordinate data on a classical SNS. On the proposed system, it is possible for usersjoined in a roomto watch a vector map of same area and exchange texts. If a user builds a path on the map, the system propagates the coordinate data of the generated path and the other users joined in the room watch the path immediately. The implemented chatting systemhasthe benefit to share the information related a map between users using coordinate data.

• 전자공학회논문지 IE
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• v.46 no.1
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• pp.37-43
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• 2009

In this paper, we propose a new algorithm for 3D model retrieval based on spherical coordinate system. We obtains sample points in a polygons on 3D model. We convert a point in cartesian coordinates(x, y, z) to it in spherical coordinate. 3D shape features are achieved by adopting distribution of zenith of sample point in spherical coordinate. We used Osada's method for obtaining sample points on 3D model and the PCA method for the pose standardization 3D model. Princeton university's benchmark data was used for this research. Experimental results numerically show the precision improvement of proposed algorithm 12.6% in comparison with Vranic's depth buffer-based feature vector algorithm.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1263-1267
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• 2007

A more complete two-dimensional vertical numerical model has been developed to describe the saltwater intrusion in an estuary. The model is based on the previous studies in order to obtain a better accuracy. The non-linear terms of the governing equations are analyzed and the $\sigma$-coordinate system is employed in the vertical direction with full transformation which is recently issued in several studies because numerical errors can be generated during the coordinate transformation of the diffusion term. The advection terms of the governing equations are discretized by an upwind scheme in second-order of accuracy. By employing an explicit scheme for the longitudinal direction and an implicit scheme for the vertical direction, the numerical model is free from the restriction of temporal step size caused by a relatively small grid ratio. In previous researches, some terms induced from the transformation have been intentionally excluded since they are asked the complicate discretization of the numerical model. However, the lack of these terms introduces significant errors during the numerical simulation of scalar transport problems, such as saltwater intrusion and sediment transport in an estuary. The numerical accuracy attributable to the full transformation is verified by comparing results with a previous model in a simply sloped topography. The numerical model is applied to the Han River estuary. Very reasonable agreements for salinity intrusion are observed.

• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.4
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• pp.446-456
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• 2024

This paper addresses a novel approach to performance enhancement of the naval gun fire control system(FCS) by using the projectile tracking filter without any distortion of radar measurements. Under the assumption that the maneuvering between the projectile and the ship equipped with the radar is not quite large, this method is based on the concept of polar-coordinate target tracking, which separates the range estimation filter and the direction cosine estimation filter. Note that using polar-coordinates allows tracking to be performed in the same coordinate system from which the radar line-of-sight(LOS) measurements are obtained, unlike the conventional tracking process in Cartesian. Also, it is easy to implement in real-time and guarantees consistent estimates due to its linear filter structure. With the help of the above method, therefore, the proposed filter is able to improve the overall performance of FCS which requires stability of projectile estimates within a short engagement time. The effectiveness of the presented scheme is validated through computer simulations.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.411-413
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• 1992

This paper proposes a simple and high performance hybrid position/force control of robots based on disturbance compensation by using the disturbance observer in task coordinate space. The disturbance observer linealizes system of robot manipulators in task coordinate space and realizes acceleration control. To realize the strict acceleration control, the disturbance observer whose input is a position signal by simple computation, works as if it were a disturbance detector. The inverse kinematics can be simplified, because the disturbance observer in task coordinate space compensates not only the disturbance but also the error due to the simplification of the inverse kinematics. The new strategy is applied to a three-degrees-of freedom direct drive robot. The robust and simple hybrid position/force control is realized experimentally.

• Geomechanics and Engineering
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• v.20 no.3
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• pp.267-273
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• 2020

Solutions of the water pressure and groundwater inflow distribution along the tunnel perimeter in a half-infinite aquifer were investigated considering the conditions of the constant head and constant water pressure. It is assumed that the circular tunnel is buried in a fully saturated, homogeneous, isotropic and half-infinite space. Coordinate transformation technique was adopted, the problem of solving the control equations of water pressure in the Cartesian coordinate was transformed to that in the bipolar coordinate system, which can significantly simplify the derivation procedure of the water pressure and inflow distribution. The validation results show the accuracy and advantage of the proposed approach.