• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.13 no.2
• /
• pp.125-133
• /
• 1995

The geoidal heights of a country may be computed from astrogedetic, gravimetric or satellite data. In this paper, the geoid models to the Bessel ellipsoid(KGM95-A) have been determined by the astrogedetic method, which is surface fitting techniques using deflections of the vertical and geoid height constraints. Transformation equations and the gravimetric geocentric geoid(KGM93-C) were applied to obtain the geoid height referred to the Tokyo Datum of the Korean geodetic network, the comparison of the astrogedetic results and discussions of the geoid information were added.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2004.11a
• /
• pp.3-7
• /
• 2004

Many countries have changed her geodetic reference system from local system to global system because of the global network's necessity. And, also Korean geodetic reference system changed from Tokyo datum to Global geodetic reference system since 2003 as the revision of Survey Law and Korean reference ellipsoid changed from Bessel 1841 ellipsoid to GRS80. The purpose of this paper is evaluation of ellipsoid agreement before and after change due to the introduction of global geodetic reference system in Korea. For the evaluation ellipsoid agreement was analyzed using two Korean geoid model -KOGD2003 and KOBGDM33- on both ellipsoid and area variation caused by change of reference ellipsoid was calculated.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.17 no.3
• /
• pp.265-272
• /
• 1999

The map coordinate systems of Korea, based on the Bessel 1841 ellipsoid with Tokyo Datum, applied in digital mapping. So, the new geocentric system have some coordinate differences compared to GRS80 ellipsoid with the International Terrestrial Reference Frame(ITRF). Therefore, map transition procedures are needed to establish for the new coordinate system. In this paper, characteristics and tendencies about coordinate differences and map tiles systems are investigated and modules for the map coordinate transformations between two systems are developed and simulated.

• Economic and Environmental Geology
• /
• v.48 no.6
• /
• pp.537-543
• /
• 2015

In Korea, the use of world geodetic system(WGS) has been mandated in year 2010. Accordingly, the national geographic information institute(NGIS) provides the digital maps according to the WGS. Nevertheless, most of the digital geological maps are still based on the Tokyo Datum(TD). Therefore, users should conduct 2D/3D geological spatial analysis after converting the coordinates of digital geological maps to WGS. The conversion process is often tedious and troublesome for certain users. Therefore, in this study, the method to transform coordinate from TD to WGS using ArcToolbox is introduced for users not familiar with the process. For a better appreciation, the Chungju and Hwanggang-ri digital sheets of 1:50,000 scale was chosen as an example. Here, Chungju and Hwanggang-ri sheets were defined based on the TD-central origin and TD-east origin, respectively. The two sheets were merged after the transformation of TD-east origin of Hwanggang-ri to the TD-central origin, and eventually transformed to WGS-central origin. The merged map was found to match exactly with the digital map(Daeso 367041). The problem of coordinate determination in previous digital geological maps was solved effectively. The proposed method is believed to be helpful to 2D/3D geological spatial analysis of various geological thematic maps.

• Geophysics and Geophysical Exploration
• /
• v.13 no.1
• /
• pp.88-95
• /
• 2010

An airborne gravity survey using a helicopter was carried out in October 2008, offshore along the northern Noto Peninsula, to understand the shallow and regional underground structure. Eleven flight lines, including three tie lines, were arranged at 2 km spacing within 20 km of the coast. The total length of the flight lines was ~700 km. The Bouguer anomalies computed from the airborne gravimetry are consistent with those computed from land and shipborne gravimetry, which gradually decrease in the offshore direction. So, the accuracy of the airborne system is considered to be adequate. A local gravity low in Wajima Bay, which was already known from seafloor gravimetry, was also observed. This suggests that the airborne system has a structural resolution of ~2 km. Reduction of gravity data to a common datum was conducted by compiling the three kinds of gravity data, from airborne, shipborne, and land surveys. In the present study, we have used a solid angle numerical integration method and an iteration method. We finally calculated the gravity anomalies at 300 m above sea level. We needed to add corrections of 2.5 mGals in order to compile the airborne and shipborne gravity data smoothly, so the accuracy of the Bouguer anomaly map is considered to be nearly 2 mGal on the whole, and 5 mGals at worst in limited or local areas.

• Journal of the Korean Geographical Society
• /
• v.40 no.2 s.107
• /
• pp.153-171
• /
• 2005

The newly adopted Korea Geodetic Datum (a.k.a. KGD2002) calls for massive reengineering work on geospatial dataset. The main focus of our study is placed on the strategy and system implementations of the required data reengineering with a keen attention to integrated approaches to interoperability, standardization, and database utilization. Our reengineering strategy includes file-to-file, file-to-DB, DB-to-file, and DB-to-DB conversion for the coordinate transformation of KGD2002. In addition to the map formats of existing standards such as DXF and Shapefile, the newly recommended standards such as GML and SVG are also accommodated in our reengineering environment. These four types of standard format may be imported into and exported from spatial database via KGD2002 transformation component. The DB-to-DB conversion, in particular, includes not only intra-database conversion but also inter-database conversion between SDE/Oracle and Oracle Spatial. All these implementations were carried out in multiple computing environments: desktop and the Web. The feasibility test of our system shows that the coordinate differences between Bessel and GRS80 ellipsoid agree with the criteria presented in the existing researches.

• Journal of the Korean Institute of Navigation
• /
• v.24 no.1
• /
• pp.1-12
• /
• 2000

The ships over the certain navigation area or her length are required to carry charts under the relevant laws. Charts are indispensible to the ships and fishing vessel, because their crew should know the water depth and location of obstacle in order to avoid danger in the navigation and fishing area. But it was found that many ships do not carry proper charts onboard according to the research marine accidents files of marine accident inquiry agency, and questionnaire survey. Consequently, many ships run aground on the coast and port. This study examined the present status of the coastal ship and the fishing vessels, and explained some problems in the aspect of the covering area, the place, the number of the selling agent and adjoining chart, as well as the geographical and traffic density, the crew on board the ship's characteristics, and so on. In this study we propose the way to solve the problem. firstly, the category of the fishing vessel which should carry the chart on bard under the related laws are required to be lowered to 10 gross tons. Besides a ship inspector should examine if the charts covering the area where to navigate even when the temporary inspection is done are carried on board property. Secondly, the inspection body or the controlling office of ship's entry and departure should check throughly whether the ships concerned carry the chart on board. Thirdly the fishing vessels should used the fishing charts, and the body concerned should train the offices about how to use chart, especiany the difference between Tokyo datum and WGS-84 datum. Fourthly the customized chart such as an atlas like a map, a calenda-type chart, a small chart, as a coated chart needs to be publish for the safety of small ship and fishing vessel. Fifthly, it is advisable to draw a recommended course in the route where the coastal navigate mainly and in the narrow channel, The adjoining area should be improved, as well as the qualify of the chart paper. Sixthly, publication of additional new chart in the southern part of East Sea, the eastern part of South Sea, the western part of South Sea and middle part of Yellow Sea near Incheon port should be thought over. Seventhly, the number of chart selling agent should be increased for the sake of purchaser in proportion to the number of port, and small correction of charts in selling agent must be carried out completely.

• Spatial Information Research
• /
• v.9 no.2
• /
• pp.309-324
• /
• 2001

To apply the real-time kinematic GPS surveying technique, this research has tried to obtain the TOKYO datum first from the continuous reference stations distributed all over the country. Then, analysis of the geography of a coastal area including both of land and sea has been carried out by the post-processed continuous kinematic GPS technique and the real-time kinematic GPS surveying technique. After considering the initial conditions and measuring time zone for real-time kinematic GPS, post-processed and the real-time kinematic GPS measurements have been carried out. A new system has been proposed to store measured data by using a program developed to store GPS data in real time and to monitor the satellite condition through controller simultaneously. The accuracy of GPS data acquired in real time was as good as that acquired by post processing. It is expected that it will be useful for the analysis of coastal geographic characteristics because DTM can be also constructed for the harbor reclamation, the dredging and the variation of soil movement in a river.