• Journal of Korean Society for Geospatial Information Science
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• v.22 no.4
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• pp.39-46
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• 2014

Network RTK GNSS positioning technique which has been developed to overcome the limitation of Single reference station RTK is used widely in the field of general surveying, cadastre surveying and engineering surveying due to the high accuracy and efficiency. It is specified Network RTK, Single reference station RTK and Static of GNSS as a surveying method in the regulation of Cadastre Re-survey Surveying. In this study, Network RTK and Static GNSS surveying were accomplished at cadastral re-survey field in Hadong, Gyeongnam and the surveying results were compared. Also, to analyze the performance of site calibration in Network RTK surveying, two types of Network RTK surveying with and without site calibration were accomplished and the results was compared. The research result shows that average positioning error between Network RTK(VRS) without site calibration and Static surveying result is 2.44cm and 1.53cm respectively and average positioning error between Network RTK(VRS) with site calibration and Static surveying result is 0.19cm and 0.82cm respectively at two zone. So, it was proved the effect of calibration in network RTK(VRS) surveying.

• Journal of Korean Society for Geospatial Information Science
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• v.22 no.4
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• pp.127-133
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• 2014

The purpose of this study is to evaluate the accuracy of Network-RTK(VRS) survey for applying to Ground Control Points(GCPs) survey required for mapping aerial photographs. Network-RTK has been serviced by National Geographic Information Institute since 2007. On the basis of the global coordinates system(ITRF2000), the coordinates of GCPs determined by Static GNSS survey with relative positioning techniques were regarded as accurate values. The coordinates of GCPs were also determined by Network-RTK survey using two kinds of receivers, and then they were converted into the global coordinates system(ITRF2000) by applying suitable geoid model and coordinate transformation. These coordinates of GCPs were compared with those from Static GNSS survey. The root mean squares error (RMSE) of coordinate differences between Network-RTK and Static GNSS was ${\pm}2.0cm$ in plane and ${\pm}7.0cm$ in height. Therefore, Network-RTK survey that enables single GNSS receiver to measure positions in short time is a practical alternative in positioning GCPs to either RTK survey that uses more than two sets of GNSS receivers or Static GNSS survey that requires longer observation time.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.4
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• pp.87-92
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• 2010

With recent localized heavy rain, the collapsing accident of the cut slopes occur repeatedly every year. The maintenance of the cut slopes is very crucial as the collapsing of cut slopes causes various calamities such as human causalities and sweeping away of the roads. By looking at the study of current situation of the cut slopes, designed for maintenance of cut slopes, the locations of the damaged districts are hard to figure out as they are represented through distance mark and longitude and latitude. In this paper has used NDGPS methods and VRS service through GPS signal corrections that are received by DGPS standard department to correctly analyze the exact location and the shape of the slope. The result of this analysis shows that both methods produce similar shape of the slope. Therefore, these two methods, NDGPS methods and VRS service, can be applied to other analysis of cut slopes in different areas.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.5
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• pp.469-479
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• 2014

N-RTK(Network based RTK) methods are able to improve the accuracy of GNSS positioning results through modelling of the distance-dependent error sources(i.e. primarily the ionospheric and tropospheric delays and orbit errors). In this study, the comparison of the TTFF(Time-To-Fix-First ambiguity), accuracy and discrepancies in horizontal/vertical components of N-RTK methods(VRS and FKP) with the static GNSS at 20 Unified Control Stations covering Incheon metropolitan city area during solar storms(Solar cycle 24 period) were performed. The results showed that the best method, compared with the statics GNSS survey, is the VRS, followed by the FKP, but vertical components of both VRS and FKP were approximately two times bigger than horizontal components. The reason for this is considered as the ionospheric scintillation because of irregularities in electron density, and the tropospheric scintillation because of fluctuations on the refractive index take the place. When the TTFF at each station for each technique used, VRS gave shorter initialization time than FKP. The possible reasons for this result might be the inherent differences in principles, errors in characteristics of different correction networks, interpolating errors of FKP parameters according to the non-linear variation of the dispersive and non-dispersive errors at rover when considering both domestic mobile communication infra and the standardized high-compact data format for N-RTK. Also, those test results revealed degradation of positing accuracy, long initialization time, and sudden re-initialization, but more failures to resolve ambiguity during space weather events caused by Sunspot activity and solar flares.

• Journal of Advanced Navigation Technology
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• v.18 no.6
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• pp.546-554
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• 2014

For improvement of network RTK performance in survey field, Spatial Information Research Institute (SIRI), LX Korea Cadastral Survey Corporation installed 30 GNSS permanent stations in Korea Peninsula, and has been running the MAC-based network RTK service as a test version. In this paper, we introduce the LX GNSS network and analyze the positioning accuracy of the LX MAC RTK service. For field test of the LX MAC RTK service, we installed temporally fixed anchor points and observed simultaneously with VRS of National Geographic Information Institute. As a result, the horizontal position differences and initial times of LX MAC with respect to NGII VRS are $1{\sim}2{\pm}1cm$ and <10 seconds, respectively.

• Journal of The Korean Society of Integrative Medicine
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• v.4 no.1
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• pp.1-11
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• 2016

Purpose : The purpose of this study was to exam effects of aroma therapy on the woman with headache in range of motion, results based on Pain and the tiredness index. we applied this study in female patients with headache. tiredness, stress, pain to examine effects of easing off headache, Tiredness. Methods : The study has been conducted with three different groups of "H" University in Gwangyang, the forty-five 20's female university student with headache were randomly assigned to groups each groups did a survey to evaluate their tiredness, VAS, VRS before this study and after there are three groups: 15 people gets a swedish massage by using almond oil(I Group, n= 15), 15 people got a swedish massage by using lavender oil(II Group, n=15) and 15 people got a swedish massage by using lavender oil, smalled at the scent of lavender candle(III Group, n=15). I, II, III Group common characteristics(gender, age, height, weight) were measured by using goniometer to measured flexion extension, left right flexion, left right rotation of cervical range of motion. the measured data were analyzed by using repeated ANOVA. Especially in order to investigate the effect of Aroma therapy by using lavender candle this study is progressed 20 minutes, 3 times per week for a term of 3weeks(total 9). Results : The results of this study were as follows : 1) the VAS and VRS showed significant different result. 2) in the range of motion, cervical extension between Group I and II and left right flexion between Group I and III showed quite motional difference. 3) in the tiredness, there were no significant factors after examination. Conclusion : Therefore, the results of this study demonstration that the effect of Aroma therapy by using lavender candle didn't show prominent effects.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.3
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• pp.175-186
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• 2017

In this study was to survey method of national/public land actual condition survey to utilization of UAV, in order to evaluate the economic and accuracy. we carried out the comparative evaluation of the cadastral status surveying in terms of accuracy of parcel checkpoint, economical costs. The results are summarized as follows. First, average position error of the orthoimage was 0.033m in X error, 0.023m in Y error when the RMSE average calculated 0.046m from the intersection of plane distance connections. Secondly, it was appeared the accuracy of the orthophotograph is 0.076m at the maximum RMSE of the UAV orthoimage check point and 0.042m at the minimum RMSE compared with the VRS-GNSS survey results. Thirdly, when the allowable error specified in the implementing regulation of the current cadastral survey is applied, all of the checkpoint of 0.360m tolerance corresponding to the scale of 1/1,200 is satisfied. Finally, UAV utilization method in national/public land actual condition survey is 26,497,436(KRW) cheaper than cadastral survey method for In the economic evaluation of national/public land actual condition survey. Therefore, as a result of this study shows that the method of utilizing UAV in the national/public land actual condition survey satisfies legal standards in terms of accuracy and economical aspect is a way to further reduce the local government budget.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2010.04a
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• pp.191-193
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• 2010

In this study, compared with national control point offering in NGII executing Network-Based RTK measurement. As a result, can utilize in various field such as Geodetic Survey/GIS, ITS, Car Navigation, Mobile because error of actuality coordinate and about 0.5m publishes.

• Journal of Korea Water Resources Association
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• v.53 no.12
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• pp.1049-1057
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• 2020

This study aimed to develop a flow measurement method using drone in flood season. Measuring flow in all branches is difficult to conduct annually due to budget and labor limitation, safety and river works. Especially when heavy rain like storm comes, changes in stage-discharge relationship should be reviewed; however, it is usually impeded by the aforementioned issues. To solve the problem, it developed a simple measuring method with a minimum of labor and time. A numeric map and numeric orthophoto coordinate of South Korea are mostly based on Transverse Mercator Projection (TM) in accordance with rectangular coordinate system and use World Geodetic Reference System 1980 (GRS80) oval figure for conversion. Applying a concept of aerial photogrammetry, it located four visible Ground Control Points (GCP) near the river at Uijeongbu-si (Singok Bridge) and Yeongdong-gun (Youngdong 2nd Bridge) station and measured the coordinates using VRS DGPS. Hovering at a same level, drones took orthophoto of water surface at an interval of 3 seconds. It defined the pictures with GRS80 TM coordinate system, a rectangular coordinate system and then conducted an orthometric correction using GCP coordinates. According to X and Y coordinate analysis, it estimated the distance between the floating positions at 3 seconds-intervals and calculated the flow through the flow area according to the flow path. This study attested applicability of the flow measurement method using drone in flood season by applying the rectangular coordinate system based on the concept of aerial photogrammetry.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.1
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• pp.67-73
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• 2021

The need for precise location data is growing across numerous markets, and so is the number of affordable high-precision GPS receivers. In this paper, we validated the performance of RTAP2U, a low-cost high-precision RTK receiver that was recently released. Two positioning modes were tested: static and driving. The static test conducted Zero-Baseline Single-RTK and Network-RTK survey for 57 hours and 51 hours, respectively. For the driving test, Network-RTK survey was conducted using VRS services provided by NGII based on Trimble PIVOT and Geo++ GNSMART. The static test showed about 1 cm horizontal and vertical accuracies, which is very stable considering the test duration longer than 50 hours. The integer ambiguity FIX rate marked a solid 100%. The driving test result also reached a 100% FIX rate. Horizontal and vertical accuracies were better than 2 cm and 3 cm, respectively. Researchers can refer to this paper when considering affordable high-precision GPS receivers as an option.