• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.1
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• pp.110-120
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• 2008

Gridded bathymetric data of 30 seconds apart in Korea marginal seas $(30^{\circ}N{\sim}44^{\circ}N,\;117^{\circ}E{\sim}143^{\circ}E)$ are produced. In order to make the data, both updated gridded data of 1 minute apart on internet sites and all the digital nautical charts issued by National Oceanographic Research Institute (NORI) in Oct. 2007 are used. The reference level of the gridded data is approximate level of lowest low water and the horizontal coordinates are based on the WGS84 ellipsoid. Especially a developed computer program can collect all the sounding data including depth contour directly from the digital charts and UTM coordinates of the data are converted to the WGS84 coordinates from which accuracy of data is significantly improved. An interpolation method is adopted to produce the gridded data which are compared and analyzed against the existing gridded data. In this gridded data we can see significantly detailed topographic features which could not be found in the previous data.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.3
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• pp.277-290
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• 2008

In order to apply UTM coordinates conversion in zones larger than $14^{\circ}$ wide, a new conversion formula, based on the 12th expansion of Taylor series, is derived which is shown to be an extension of Thomas' formula(1952). Some examples of coordinate conversion between WGS84 and UTM are presented and convergences of computational results are also tested according to the order of formula. The present conversion formula can be used to make rectangular coordinate grid systems for numerical models to compute long wave propagation such as tide or tsunami around Korea.