• Bulletin of the Korean Mathematical Society
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• v.47 no.1
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• pp.73-79
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• 2010

A pair of point vortices of the same strength but opposite sign is called a vortex dipole. We consider the limiting case where two vortices approach infinitely close while the ratio of the strength to the distance kept constant. The motion of such point vortex dipole on the ellipsoid of revolution is investigated geometrically to conclude that the trajectory draws a geodesic up to the leading order of perturbation, whose direction is determined by the initial orientation of the dipole. Related issues are also remarked.

• Bulletin of the Society of Naval Architects of Korea
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• v.9 no.1
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• pp.1-6
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• 1972

To contribute towards more accurate estimation of the virtual coefficient for the vertical vibration of the chine-type ship, experimentally obtained three-dimensional correction factors, J, of added mass of prismatic beams having cross section shape of hypotrocoid characters, slightly concaved Lewis form and elliptic form are investigated in connection with the applicability of an approximate analytical calculation method compared to that proposed by T. Kumai[6] for the Lewis form cylinders, and synthetically in compared with the experimental works on various cross section shapes of the other type by L.C. Burril et al[8] and the analytical works on the ellipsoid of revolution by F.M. Lewis[1] and J.L. Taylor[2]. The experimental results show that the aforementioned analytical method gives, unlike that for the Lewis form cylinders, considerably larger J-values for the chine-type cylinders, and that the influence of the character of the cross section shape on J-values is not remarkable in practical sense. Finally, considering in synthesis the experimental results on prismatic beams, the Burril's works on palabolic plan form and elliptic plan form, and that the chine-type ship usually has a hull form of transom stern, it is fairly safe to say, at the present stage, that adoptation of the Taylor's J-values will not results in any large error in estimation of the virtual inertia coefficients of the chine-type ships.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.15 no.2
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• pp.269-275
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• 1997

Car Navigation System with Global Positioning System (GPS) can display position direction and the shortest cut of one's destination. The position datum for GPS in World Geodetic System 1984 (WGS-84) coordinates system need to transform Bessel coordinates system and process Map projection. Since 1987, GPS has used the WGS-84. WGS-84 is a geocentric equipotential ellipsoid of revolution which is defined four parameters. In this study, by comparing the digitized topographical map with the digital map of GPS datum we can consider the technique of WGS84 digital map.