• Korean Journal of Remote Sensing
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• v.18 no.6
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• pp.345-358
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• 2002

DGPS(Differential Global Positioning System) and RTK(Real time Kinematic) are in one of today's most widely used surveying techniques. However surveying with these techniques is restricted by the distance between reference and rover station, and it is difficult to process data in realtime by their own organizational limitation in precise measurement of positioning. To meet these new demands, in this paper, new DGPS and RTK correction data services through the Internet and PSTN(Public Switched Telephony Network) have been proposed. For this purpose, a DGPS and RTK error correction data transmission system is implemented for long-distance using the Internet and PSTN which allows a mobile user at which the rover receiver is located to receive the correction data from the reference in realtime, and analyzed and compared with DGPS and RTK performances by experiments through the Internet and PSTN for the distance and the time.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.4
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• pp.158-168
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• 2019

Korea Hydrographic and Oceanographic Agency(KHOA) carried out a research project named 'Marine Fisheries Infrastructure Construction and Technology Training for the Philippines' as part of the 1st Official Development Assistance(ODA) from 2015 to 2018. It is preparing for the 2nd ODA project which will begin in 2020. Besides, recently, the Philippines is paying attention to marine territory management and response capability due to problems such as the sea-level rise and coastal erosion caused by climate change. Therefore, before 2nd ODA to the Philippines, this study analyzed the vertical ocean model on the vertical datum in Korea and suggests the direction of development of the vertical ocean modeling system for the vertical datum in the Philippines using the observed data from the permanent tide station which was built by the Philippines ODA research project over the last four years. Moreover, as a pilot study, the Sulu Sea in the Philippines was selected and analyzed by harmonic analysis method. At each tide station, constants for correction had been computed. And the grid-based tidal model was constructed based on this study. As a result of the study, similar tidal characteristic were observed when the prediction and the measured tide were compared by applying the constants for correction between two station in the sea area with similar tidal level. These results could be used as basic data for the 2nd ODA to the Philippines, and contributed to construct and maintain a close cooperation and friendship between Korea and the Philippines.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.395-399
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• 2001

In this paper, various reduced parts converter topologies and control strategies for power factor correction and motor control are reviewed and systematic design methodology is developed. From this investigation, the converter topologies could be mainly categorized into cascade type and unified type. The detailed operational principles are examined and the performance comparison is derived to illustrate merits and limitations of the converters. Simulation results are provided to help the better understanding of the theoretical description and several experimental results are presented on prototype induction motor better brush less dc (BLDC) motor drives, along with cascade and unified type converters.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2017.11a
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• pp.199-200
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• 2017

In order to meet the international performance requirements for eLoran testbed operation, it is necessary to measure ASF (Additional Secondary Factor) of vessel's route as well as differential correction and the provision using differential Loran (dLoran) station operation. According to HEA (Harbor Entrance and Approach) performance of the IMO, the position accuracy should be within 10meters. Therefore this paper presents the possibility to meet the position accuracy of the IMO HEA through simulation results.

• Journal of Advanced Navigation Technology
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• v.12 no.6
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• pp.634-639
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• 2008

In mobile communication networks, the main power consumption is due to the actual transmissions power. Therefore, power efficiency network structures have gained considerable importance in mobile multi-hop systems and networks in recent years. In this paper, the performance of mobile multi-hop wireless system with M-QAM signal and forward error control (FEC) technique are analyzed The FEC technique uses extra processing power related to encoding and decoding, it is need complex functions to be built into the communication node. The probability of receiving a correct bit and codeword for relaying a data frame over h hop relay station to the final station is evaluated as a function of channel parameter and number of hops, and the distance between the different station.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.4
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• pp.299-307
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• 2007

This study is about the calculation of practical orthometric height for permanent GPS station. We presented the method to determine the orthometric height precisely by combining leveling data, GPS data and gravimetry data, and determined the orthometric heights of thirty GPS stations. To test the result we developed the expected error model fur the determined orthometric heights regarding the accuracy of Korean national benchmarks and the precision of surveying methods used at this project. The reliability of the results was presented by comparing it with expected error model statistically.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.53-53
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• 2000

In this paper, we introduce the real-time skier-training software using DGPS. We used a PCS to receive the pseudorange correction messages from the reference station. We tested the performance of this system and could get a skier's position in real-time with high accuracy. It can help skier-trainers to monitor a skier's trajectory and teach him mote effectively This paper will show you how the system works and prove it has good performance.

• Geophysics and Geophysical Exploration
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• v.12 no.3
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• pp.225-232
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• 2009

As part of seismic experiments investigating crustal velocity structures of the Korean peninsula, permanent (fixed) seismographs of the Korea Meteorological Administration (KMA) network recorded seismic signals from four and eight large explosions in Korean Crustal Research Team (KCRT) profiles shot in 2004 and 2008, respectively. Among the seismograms recorded by 43 velocity sensors and 103 accelerometers at KMA stations distributed throughout the southern Korean Peninsula, 156 records with epicentral distances less than 120 km and high signal-to-noise ratios were analyzed to determine velocity anisotropy of the Pg phase. Relative elevation corrections of -101.6 to 105.3 ms were made using velocity information derived from the 2004 KCRT profile data and differences in elevation between the permanent KMA stations and the temporary stations in the KCRT profiles at the same source-receiver offsets. To remove site effects, receiver-station corrections of -89.6 to 192.2 ms were additionally made to the KMA station data by subtracting the average differences in traveltimes between KMA stations and portable stations at the same offsets for all available shots with different azimuths. With the exception of anomalously fast velocities along trends of the Chugaryeong fault zone and the Okchon fold belt and anomalously slow velocities in the regions of high terrestrial heat near Yeongduk and Ulsan, the analysis of crustal velocity anisotropy using the Pg phase indicates overall isotropy in the southern half of the Korean peninsula.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.22 no.3
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• pp.57-68
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• 2017

Continuous monitoring of spatial and temporal changes in key marine environmental parameters such as SST (sea surface temperature) near IORS (Ieodo Ocean Research Station) is demanded to investigate the ocean ecosystem, climate change, and sea-air interaction processes. In this study, we aimed to develop the system for continuously measuring SST using a TIR (thermal infrared) sensor mounted at the IORS. New SST algorithm is developed to provide SST of better quality that includes automatic atmospheric correction and emissivity calculation for different oceanic conditions. Then, the TIR-based SST products were validated against in-situ water temperature measurements during May 17-26, 2015 and July 15-18, 2015 at the IORS, yielding the accuracy of 0.72-0.85 R-square, and $0.37-0.90^{\circ}C$ RMSE. This TIR-based SST observing system can be installed easily at similar Ocean Research Stations such as Sinan Gageocho and Ongjin Socheongcho, which provide a vision to be utilized as calibration site for SST remotely sensed from satellites to be launched in future.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.78-79
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• 2012

To improve moving vehicles' accuracy, one-way Network RTK which guarantees high accuracy and integrity regardless the distance from rovers to Reference Station(RS) is being considered. Correction of one-way Network RTK can be generated only after constructing RS network surrounding the rover, therefore a correction discontinuity is inevitably occurred when the RS set has been changed. The discontinuity is not eliminated by the DD(Double Difference) method, and our simulation shows that it causes 13cm(horizontal) and 48cm(vertical) position error. We suggest three solutions to reduce this discontinuity, which are identification of master RS with neighbor networks, duplication of communication module to receive corrections from other network, and ambiguity levelling between neighbor networks.