• Journal of Positioning, Navigation, and Timing
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• v.3 no.3
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• pp.117-122
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• 2014

In CDGPS, ambiguity resolution is determined by the performance of a floating solution, and thus, the performance needs to be improved. In the case of precise positioning at a stationary position, the batch method using multiple measurements is used for the accuracy improvement of a position. The position accuracy performance of a floating solution is outstanding, but it has a problem of high computation cost because all measurements are used. In this study, to improve the floating solution performance of the initial static user in CDGPS, a floating solution method using a recursive filter was implemented. A recursive filter estimates the position solution of the current epoch using the position solution of up to the previous epoch and the pseudorange measurement of the current epoch. The computation cost of the floating solution method using a recursive filter was found to be similar to that of the epoch-by-epoch method. Also, based on actual GPS signals, the floating solution performance was found to be similar to that of the batch method. The floating solution using a recursive filter could significantly improve the performance of the prompt initial position and ambiguity resolution of the initial static user.

• Journal of Ocean Engineering and Technology
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• v.23 no.3
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• pp.6-13
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• 2009

Based on the boundary element method, the motion responses and transmission coefficients of a moored floating breakwater were investigated in oblique waves. To satisfy the outgoing radiation condition in the far field, the fluid domain was divided into inner and outer regions. The complete solution could be obtained by applying the matching conditions between the eigenfunction-based outer solution and BEM-based inner solution. Using the developed predictive tools, the wave exciting forces, added mass, damping coefficients, motion responses, and transmission coefficients were assessed for various combinations of breakwater configuration, wave heading, mooring cables properties, and wave characteristics. It was found that the transmission coefficient for a moored floating breakwater was closely dependent on the motion responses, which were greatly amplified at the resonant frequencies.

• Journal of The Korean Digital Architecture Interior Association
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• v.11 no.3
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• pp.43-51
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• 2011

Currently the locations of Unpleasant Facilities, especially surrounding the site selections, have been causing conflicts among the national government, many local governments and local residents. These Unpleasant Facilities must be necessary facilities for people's modern cultural lives, but there is no obvious solution that will make us all pleasant for the locations of them until now. In this study, we'll focused on applying the Floating architecture, one of the variety of marine structures, as an alternative location of Public service facilities accommodating Unpleasant Facilities which are classified as public service facilities. Of course, there should be beforehand studies in which we can define Unpleasant Facilities and analyse the conflicts surrounding the locations of them, and we can suggest that applying the Floating architecture should be the very solution to solve all these problems together. And as our main study, we should research and develop the structure and construction, maintenance and management of the Floating architecture which will be applied to the Unpleasant Facilities, together with the environmental considerations of their emergence on the waters. In future, to secure Unpleasant Facilities sites will become more and more difficult, and so Various kinds of public service facilities will have to be the subject to the floating construction.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.6
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• pp.563-570
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• 2014

This paper purposes on stimulating the dynamic behavior of a floating structure model with the image processing and the close-range photogrammetry, instead of the contact sensors. Previously, the movement of structures was presented by the exterior orientation estimation from a single camera following the space resection. The inverse resection yields to 6 orientation parameters of the floating structure, with respect to the camera coordinates system. The single camera solution of interest in applications is characterized by the restriction in terms of costs, unfavorable observation conditions, or synchronization demands when using multiple cameras. This paper discusses the theoretical determinations of camera exterior orientation by using the least squares adjustment, applied of the values from the DLT (Direct Linear Transformation) and the photogrammetric resection. This proposed method is applied to monitor motions of a floating model. The results of 6DOF (Six Degrees of Freedom) from the inverse resection were signified that applying appropriate initial values from DLT in the least square adjustment is effective in obtaining precise exterior orientation parameters. Therefore, the proposed method can be concluded as an efficient solution to simulate movements of the floating structure.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.10a
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• pp.219-221
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• 2014

The objective of this paper is to simulate the dynamic behavior of a floating structure model, using image processing and close-range photogrammetry, instead of the contact sensors. Previously, the movement of structure was presented through the exterior orientation estimation of a single camera by space resection. The inverse resection yields the 6 orientation parameters of the floating structure, with respect to the camera coordinate system. The single camera solution is of interest in applications characterized by restriction in term of costs, unfavorable observation conditions, or synchronization demands when using multiple cameras. This article discusses the theoretical determinations of camera exterior orientation based on Direct Linear Transformation and photogrammetric resection using least squares adjustment. The proposed method was used to monitor the motion of a floating model. The results of six degrees of freedom (6-DOF) by inverse resection show that the appropriate initial values by DLT can be effectually applied in least squares adjustment, to obtain the precision of exterior orientation parameters. Additionally, a comparison between the close-range photogrammetry and total station results was feasibly verified. Therefore, the proposed method can be considered as an efficient solution to simulating the movement of floating structure.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.3 no.1
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• pp.85-92
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• 1993

Large single crystals of olivine were grown by using image furnace(floating zone furnace)under controlled partial pressure of oxygen. The transparent crystals have maximum sizes 65mm in length by 7mm in diameter. When partial pressure of oxygen was decreased, the portion of secondary phases in crystals were increased so that it made crystals dark brown. The secondary phases were proved to be solid solution of Mg, Si, and Fe by electron microprobe analysis. Mg was major portion and the rest was minor.

• Journal of the Korean Institute of Navigation
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• v.10 no.1
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• pp.129-138
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• 1986

A matrix partitioning method is proposed for the 2-D motion analysis of floating bodies. For the numerical solution, the boundary of a floating body is approximated with a series of line segments and the governing integral equation is transformed into a system of linear equations. A new solution procedure of resulting linear equation with complex coefficients is formulated and programmed using a matrix partitioning scheme and the Choleski decomposition. From the case study, it is found that the proposed method is efficient in the motion analysis of floating bodies, especially in the calculation of hydrodynamic coefficients. Also, it requires smaller memory size and less computing time compared with conventional methods.

• Journal of Ocean Engineering and Technology
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• v.23 no.4
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• pp.32-37
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• 2009

An analytic similarity shape solution was studied for a two-dimensional floating and fluid-filled membrane structure. The static shape of a membrane structure can be expressed as a set of nonlinear ordinary differential equations. The integration of curvature leads to an analytic solution for the shape, which contains unknown boundary values. Matching the upper and lower shapes at the free surface incorporated with their buoyancy allowed the unknowns to be determined. Some characteristic values of similarity shapes were evaluated and shapes are illustrated for various density ratios and volume efficiency ratios.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.184.1-184.1
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• 2010

Floating wind turbines have been suggested as a feasible solution for going further offshore into deeper waters. However, floating platforms cause additional unsteady motions induced by wind and wave conditions, so that it is difficult to predict annual energy output of wind turbines by using conventional power prediction method. That is because sectional inflow condition on a rotor plane is varied by unsteady motion of floating platforms. Therefore, aerodynamic simulation using Vortex Lattice Method(VLM) were used to investigate the influence of motion on the aerodynamic performance of a floating offshore wind turbine. Simulation with individual motion of offshore platform were compared to the case of onshore platform and carried out according to the wave height and the wave angular frequency.

• Structural Engineering and Mechanics
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• v.74 no.4
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• pp.521-532
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• 2020

A floating dry dock is an advanced structure that can provide a solution for dry dock space shortages. The critical point in floating dock operation is compensating the deflection caused by a heavy payload by adjusting the water level in the ballast system. An appropriate ballasting plan warrants safe and precise construction on a floating dock. Particularly, in the case of a 2D floating dock, ballasting plan evaluation is crucial due to complex deformation modes. In this paper, we developed a method to calculate the optimal ballasting plan for accurate and precise construction on a 2D floating dock. The finite element method was used for considering the flexibility of the floating dock as well as the construction blocks. Through a gradient-based optimization algorithm, the optimal ballasting plan for the given load condition was calculated in semi-real time (5 min). The present method was successfully used for the actual construction of an offshore structure on the 2D floating dock.