• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.7
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• pp.1350-1357
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• 2012

Korean NDGPS, which consists of the ocean-based reference station of 11 site and the land-based reference station of 6 sites, are operating. The land-based reference stations provide the output power of 500W, the service shadow regions are occurred due to mountains and nation topography. In this paper, the service coverages of land-based reference stations are analyzed in the viewpoint of output power enhancements of land-based reference stations within 1KW. Also, we suggest virtual land DGPS reference stations 2 sites to resolve the service shadow regions.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.7
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• pp.1344-1349
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• 2012

The Korean DGPS station transmits the 200 bps GPS enhancement signal using the MSK modulation in frequency range of 283.5 kHz to 325 kHz. The land-based stations of 6 sites provide the service area of 80 km with the output power of 500 W. The ocean-based stations of 11 sites provide the output power of 300 W, which provide the DGPS service to 185 kM. Some places are serviced from two or three DGPS stations. The interferences among the DGPS stations using the high power can be occurred. Also, the performances of the user terminasl in dual service area can be degraded. In this paper, the protection ratios for the DGPS service are defined. Using the MF wave propagation model, the interferences among the DGPS stations and the adjacent wireless ground stations are analyzed. Also, the performances of DGPS user terminals are analyzed in the viewpoint of interference.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.6
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• pp.1255-1261
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• 2014

Based on the radio wave measurement of korean ocean-based DGPS by season, in this paper, the service coverages of ocean-based DGPS reference stations were analyzed according to the climate and season. The signal strengths and signal-to-noise ratios in the land service areas that are provided by ocean-based DGPS reference stations were measured. The ocean-based DGPS reference station except reference stations on the mountainous terrain and the low ground conductivity provide more than 68% service area in comparison with the designed land service coverage providing by the ocean-based DGPS reference stations. To provide the designed service area that is unrelated to a season, it is necessary to install and operate the DGPS reference station with good ground conductivity and high efficiency antenna. Also, the poor service regions which is generated by obstacles of electric wave on pathway can be resolved by the double service area providing by land-based DGPS reference stations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.2
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• pp.231-236
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• 2016

The stability of DGPS signal in the DGPS service area was measured and the service availability according to the receiving signal strength was analyzed in this paper. Based on the effects of radio wave propagation in the seasons of winter and summer, daytime and night, the method to provide the DGPS service coverage was presented in this paper. The signal's strength of DGPS radio wave were measured at a constant distance from the DGPS reference station during a constant period. The propagation of DGPS radio wave is affected by status of ground conductivity, so the DGPS service area is dependant on the ground conductivity. To provide the stable service coverage, it is necessary to apply the adaptive power control for receiving signal's variations and the antenna design for alleviation of high elevation's radiation.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.3
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• pp.328-333
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• 2012

Current differential GPS (DGPS) system consists of reference station (RS), integrity monitor (IM), and control station (CS). The RS computes the pseudorange corrections (PRC) and generates the RTCM messages for broadcasting. The IM receives the corrections from the RS broadcasting and verifies that the information is within tolerance. The CS performs realtime system status monitoring and control of the functional and performance parameters. The primary function of a DGPS integrity monitor is to verify the correction information and transmit feedback messages to the reference station. However, the current algorithms for integrity monitoring have the limitations of integrity monitor functions for satellite outage or anomalies. Therefore, this paper focuses on the detection and identification methods of satellite anomalies for maritime DGPS RSIM. Based on the function analysis of current DGPS RSIM, it first addresses the limitation of integrity monitoring functions for DGPS RSIM, and then proposes the detection and identification method of satellite anomalies. In addition, it simulates an actual GPS clock anomaly case using a GPS simulator to analyze the limitations of the integrity monitoring function. It presents the brief test results using the proposed methods for detection and identification of satellite anomalies.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.153-156
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• 2006

국제해사기구(IMO) 권고에 따라 도입된 우리나라의 해양용 DGPS 기준국 구축과 국무총리 훈령에 의거 추진 중인 내륙용 DGPS 기준국의 운영현황 등을 기술하고 DGPS 기준국과 GPS 상시관측소간의 서로 다른 제원에 따른 후처리데이터의 신뢰도 품질체크를 TEQC 프로그램을 통해 비교 ${\cdot}$ 분석했다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.11a
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• pp.248-251
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• 1998

본 연구에서는, GPS 기준점(Optimal reference point)을 기준으로 한 DGPS(Differential Global Positioning System)와, 준 기준점(Sut-optimal reference point)을 기준으로 한 DGPS 시스템을 구현하였다. 이러한 2가지 DGPS 시스템으로부터 얻은 위치를 분석 평가하고, 그 결과를 나타냈다. 실험 결과, 준기준점을 기준으로 하는 DGPS 시스템은, 기존의 DGPS 기준국을 사용하지 않더라도 정밀 위치 측정이 가능함을 나타내었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.303-305
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• 2014

현재 한국에서 설치, 운영되고 있는 DGPS 기준국은 RTCM의 DGPS 기준국 관련 표준인 RSIM 버전 1.2를 기반으로 제작되어져 있다. RSIM 버전 1.2는 GPS의 보정정보를 생성하는 기준국을 위해 제정된 표준으로 현재의 다양한 GNSS들에 대한 보정정보를 서비스하는 것은 불가능하다. 이에 RTCM에서는 GPS외에 다양한 GNSS들을 지원할 수 있도록 새로운 기준국 표준 버전인 RSIM 버전 1.3을 제정하고 있다. 이러한 시점에서, 한국의 DGPS 기준국이 DGNSS 기준국으로 발전하여 각 GNSS의 보정정보를 서비스하기 위해 필수적인 신규 버전 기반 소프트웨어 RSIM 시스템을 개발하기 위해 본 논문에서는 RSIM 버전 1.3의 특징을 분석하고 소프트웨어 RSIM에서 구현되어야 하는 필수 기능들을 도출하였다.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.4
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• pp.491-499
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• 2011

Starting with maritime DGPS base stations of Palmido, Ochongdo which have been operated since 1999, truly our nation has become the most powerful country possessed with total of 17 DGNSS base stations in the field of DGNSS operation infrastructure. This paper examines into the country's DGNSS services as measuring the service range of the maritime DGPS base stations in the domestic ferry lines which sections are from Jeju to Incheon, from Busan to Jeju, from Jeju to Nokdong, the propagation characteristics of the radio waves of 300 kHz bands on sea and land path. As a result of identifying the service range of the DGPS in the sea routes of the southern sea and the western sea, the measured results of the DGPS signals are confirmed more than 100 NM(recommended service range). It can be possible to practical use the position information, which is safe navigation and various marine traffic management systems. It will be useful an expansion of maritime DGPS reference station in the near future.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.5
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• pp.921-927
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• 2006

The current DGPS technique is many problems that is permission of radio station using RF Wireless Modem, that is influence of geographic obstacle using radio wave, that is frequency interference, that is finiteness of frequency resources. In this paper, we are solved many elements, IM(Interface Module) replaces RF Wireless Modem, we suggest transmission technique of correction message using mobile phone, we researched Interface Module development which is linkage of DGPS receiver and mobile phone. IM can transmit correction message passing RS-232 port and modem communication control. IM of base station is initialized RS-232 port and modem to move station for correction message transmission, IM waited response mode. IM of move station is initialized RS-232 port and modem, IM requests hand shaking to base station, completed connection establishment. Users are worked Differential surveying using receiving correction message between mobile phones.