• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.2
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• pp.149-157
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• 2009

The orbit ephemeris of Global Positioning System(GPS) is one element to determine the surveying accuracy and there are broadcasting ephemeris and precise ephemeris, IGS rapid orbit and IGS ultra rapid orbit in the orbit ephemeris of GPS. In this study, test area was selected in Uljin, Kyungsanbukdo and GPS surveying was accomplished at 37 points in the test area. Then baseline solution was done on 74 baseline using broadcasting ephemeris and precise ephemeris and analysis by TGO and the results were compared. Comparison results were showed that there were nearly no difference between the two results but in case of relative precision of the baseline, it was slightly better the baseline results of precise ephemeris which showed 0.706ppm than the baseline results of broadcasting ephemeris which showed 0.708ppm.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2002.10a
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• pp.63-66
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• 2002

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.20 no.4
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• pp.359-366
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• 2002

To survey satellites using only GPS can sometimes cause an impossible situation due to the many different geographical conditions as city cannon and obstacles. Although the GLONASS satellite system does not have the ability to survey itself accurately since it currently lacks of the number of usable satellites, it is able to bridge the gap when combined with GPS. This research used the GPS receiver to perform four analyzing methods to bring out the independent surveying method of GPS and combined surveying method of GPS and GLONASS(4 methods - number of satellites able to receive, precision of raw data, standard deviation from known point and RTK surveying). The result of test surveying satellites showed that 11 hours were possible to measure a minimum of 4 satellites when using an independent surveying method and 4 hours in unified surveying method in a month. Also, the precision of raw data using GPS and GLONASS surveying is 0.08~l.8m better than the GPS surveying in standard deviation. The deviation of known points by GPS and GLONASS also showed better accuracy by 3~l1mm. The RTK showed the range of differences in deviation of survey by leaning towards the GPS independent survey in Northing coordinate and leaned towards the Easting coordinate when GPS and GLONASS were combined. Nonetheless, it can't be said that the unified method is better, because it has limits to its capability.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.57-57
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• 2004

This study analyzed and compared the results of baseline processing using Epoch-By-Epoch algorithm which is not required initialization compared to conventional kinematic surveying which is required initialization There are rarely differences between 24 hours data of 30 seconds interval and 90 seconds of 30 seconds when it is processed with 26km baseline. This helps with economic surveying using data of GPS CORS

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.13 no.2
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• pp.245-275
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• 1995

Surveying related papers and books presented and published since 1957 in Korea are investigated and gathered, and the list by the topics of the papers is prepared. And changes in the topics of surveying related researches are studied through the changes in the titles of the presented papers. The fields of general surveying and photogrammetry have been doing their role to lead surveying researches since 1957, and those of Geodesy, Remote Sensing, GIS and GPS are rapidly growing as advanced fields. Especially GIS is a widespreading field as being used in many socio-environment parts, recently gets a big attentions by the National GIS Project. GPS and Remote Sensing have contributed to make the surveying area an advanced technology by employing newly developed technigues to GPS receivers and satellite imagery.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.2
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• pp.213-223
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• 2009

In geoid modelling field, it is very important the GPS/leveling data because it could be check-out the accuracy of gravimetric geoid and computed the hybrid geoid. In this study, GPS surveying was accomplished in the test area including mountainous area to improve the GPS/leveling data density in Korea. And the geometric geoidal heights was calculated using the GPS/leveling data in the test area and the accuracy of the geoidal heights was analyzed. For this study, GPS surveying was accomplished on the 211 1st and 2nd order benchmarks in Gyeongbuk province and 198 GPS/leveling data were achieved after both baseline analysis and network adjustment. Geometric geoidal heights were calculated using these 198 GPS/leveling data and the accuracy analysis was done by comparison with the geoidal heights from EGM2008 geopotential model. The results showed that the bias and standard deviation computed from 190 GPS/leveling data after gross removal was -0.185$\pm$0.079m. And also, the accuracy analyses according to the benchmark order, baseline length, and altitude were accomplished.

• Journal of Korean Society for Geospatial Information Science
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• v.8 no.2 s.16
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• pp.101-108
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• 2000

Kinematic GPS surveying which can be obtained many three-dimensional topographical informations through a short-time measurement is being utilized mainly in the short base line of a few km and below The coordinate for the long base line depends on Static GPS surveying But it needs long time measurement. Therefore, the method which can decide a position of the long base line for a short time is being needed. To examine a possibility of an efficient use of kinematic GPS surveying of the long base line, this research has analysed an accuracy of the base line by static GPS surveying according to baseline distance, ephmeris, and observation time. As the results of research, I could see that accuracy was very low in case of the occurrence of cycle slip. When we use of precise ephmeris, we obtained 1ppm and less of accuracy with one-minute kinematic GPS surveying within 70km. If a lot of studies about the long baseline kinematic GPS surveying are processed, a topographical information necessary for each kind of construction field including land development could be utilized more efficiently.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.17 no.3
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• pp.301-309
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• 1999

Real-time kinematic (RTK) GPS surveying which allows centimeter level accuracy of three-dimensional coordinates without post-processing has become recognized as a major advance in GPS technology. Employing On-The-Fly initialization technique, the RTK system can escape from cycle slip problems that have affected as a main obstacle factor in traditional kinematic and static approaches. The objective of this research was to evaluate accuracy and effectiveness of the RTK-GPS surveying. First, the continuous RTK observation of a base line was conducted for the purpose of finding out the repeatability of the RTK surveying and the results which were then compared against results from static surveying showed RMS errors of $\pm{3mm}\;and\;\pm{13mm}$ for their respective horizontal and vertical components. On a test network of 30 stations covering the small area, the results of RTK testing were compared against those from not only post-processing kinematic and rapid-static surveyings but conventional surveyings and also the efficiency of RTK were analyzed. In addition, geoid heights which were derived by combination of GPS and spirit leveling about all of the points within the network were compared against those derived by the PNU95 and EGM96 models respectively.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.21 no.4
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• pp.373-381
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• 2003

This study presents the detailed methods for facilities mapping using GPS and Totalstation. From the control survey by GPS network adjustment, the level of significance fur the height value of fourth order triangulation stations used in this study was estimated about 10cm. According to the result of verification for the transformation coefficients of national coordinate, which were announced by the National Geographic Information Institute, RMSE f coordinate transformation was found out as $\pm$0.546m that can be applied to a map scale less than 1/10,000. The accuracy analysis of height determination by Totalstation for the traverse points spaced average 90m showed that RMSE came out $\pm$9mm on the basis of direct leveling, so it indicated that trigonometric leveling by Totalstation was correct comparatively. The result of accuracy analysis of GPS/RTK surveying on traverse points showed that RMSE came out $\pm$33mm in horizontal location on the basis of Totalstation's outcome and $\pm$15mm in height value on the basis of direct leveling. In the construction survey, GPS/RTK surveying is quicker and more economical than Totalstation surveying in the feasible areas of GPS surveying. but there were many impossible areas for GPS/RTK surveying by the obstacles like a building.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.10a
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• pp.27-31
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• 2003

It can be classified in various methods to get the geoidal heights. It can be achieved geometric geoidal heights if we do GPS surveying in leveling point. The aims of this paper are calculation of geometric geoidal heights using GPS/leveling data in study area and evaluation of the global and local geoid models in and around Korean peninsula. For this study, study area was selected in the leveling line from Kunsan to Chonju city and GPS surveying was accomplished in the leveling line. And, also spherical harmonic analysis was made on the three global geopotential models, OSU91A, EGM96, EGM96m under same condition and KOGD2002, Korean gravimetric geoid model was made in this study The results shows that EGM96m is the best model because the differences between geoidal heights of EGM96m and geometric geoidal heights of GPS/Leveling data appear the smallest value among them.