• 한국측량학회:학술대회논문집
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• 한국측량학회 2010년 춘계학술발표회 논문집
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• pp.177-180
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• 2010

In cadastral field GPS mainly applies to fundamental survey, while there are numerous research about cadastral detail survey using GPS application in order to increase surveying efficiency as survey technology improve. The purpose of this experiment is to analyze the accuracy of position and estimate the efficiency of GPS/GLONASS combination surveying with control points. As the result of this experiment, Network RTK-GPS/GLONASS combination survey is superior to Newtork RTK-GPS with respect to position accuracy and work efficiency.

• 한국측량학회지
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• 제29권4호
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• pp.367-380
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• 2011

본 논문에서는 지각판 운동 지진과 같은 급격한 지각변동을 고려한 국가기준점의 상시적 성과 산정 체계 수립에 관한 연구를 수행하였다. 이를 위하여 GPS 기준점의 국내 현황 및 최근 국가기준점의 재정비가 이루어진 국외 사례 조사로부터 시사점을 도출하고 GPS 상시관측점으로 이루어진 위성기준점망과 6,900 여점으로 이루어진 단일 GPS 망으로 단순화된 국가기준점의 계층 구조를 제안하였다. 또한, 초고정밀 다중기선해석과 정규방정식의 누적에 의한 연속조정을 통한 단계별 위성기준점의 성과 산정 절차 및 다중 세션 조정에 의한 단일 GPS 기준망의 성과 산정 방안을 제시하였다. 또한, 시험 조정망을 구성하여 조정계산을 실시하고 결과 분석을 통해 상시적 성과산정의 필요성과 제안한 성과산정 방법 및 절차의 타당성 등을 평가하였다.

• 한국지리정보학회지
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• 제16권4호
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• pp.54-63
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• 2013

Network RTK-GPS 방식을 이용하여 거리별 수직위치결정 한 결과, 종래의 수준측량방법보다 신속 정확하게 취득할 수 있었으며, 비교적 효율적이고, 경제적인 방법으로 판단된다. 본 연구에서 상시관측소를 검증한 결과 가시 위성수 및 PDOP(위치정밀도 저하율), 수직위치결정에 영향을 많이 미치는 VDOP(수직정밀도저하율)은 수직위치 결정에 매우 양호한 것으로 나타났다. 통합기준점 U0997과 U0921은 공공수준측량규정 3등급에 만족하였고, 나머지는 모두 부적합한 결과로 분석되었다. Network RTK-GPS를 이용하여 수직위치결정을 측량을 할 때에는 반드시 EGM2008의 지오이드 고를 적용하는 것이 바람직하다. 향후 측지위성의 수가 증가한다면, Network RTK-GPS를 이용한 수직위치결정은 전 범위에서 가능하다고 판단된다.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2008년도 정보통신설비 학술대회
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• pp.237-241
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• 2008

Femtocells are cellular access points that connect to a mobile operator's network using residential DSL or cable broadband connections. They have been developed to work with a range of different cellular standards including CDMA, GSM and UMTS. Like legacy base station, the frequency accuracy and phase alignment is necessary for ensuring the quality of service (QoS) for applications such as voice, real-time video, wireless hand-off, and data over a converged access medium at the femtocell. But, the GPS has some problem to be used at the femtocell, because it is difficult to set-up, depends on the satellite condition, and very expensive. So, some techniques are discussed to alternate with the legacy GPS system. NTP, PTP, Synchronous Ethernet use the ethernet to synchronize distributed clocks in packet networks. AGPS support reliable position information than the legacy GPS in poor signal conditions. But, These method also have some problems. So, hybrid timing method like A-GPS+PTP and TV+GPS was developed to make up the weak point of GPS. This paper introduces the each method and compare each other and y propose much better solution for timing synchronization at the Femtocell

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1024-1026
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• 2003

The purpose of establishing GPS networks of continuously operating reference stations (CORS) is aimed to assist land surveying or crustal deformation in the early stage. However, with a fast evolving and improving path the GPS technique has been extended to accurately measure atmospheric precip itable water vapor as a core objective of many projects developed in many countries and regions such as the SuomiNet (U.S., UNAVCO), COST716 (European, COST), GEONET (Japan, GSI), ...etc. In this paper, we present the current progress of the being-set-up GPS network in Taiwan whose atmospheric profile observations mainly count on the traditional radiosonde soundings as typically seen in any other part of the world. The GPS data collected from the Taiwan dense GPS network primarily supported by Central Weather Bureau are processed using the Bernese software version 4.2. Precipitable water vapor is then derived with the auxiliary surface meteorological measurements. Time series of precipitable water are examined and analyzed. A focus on the extreme weather cases is shown as an example.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.411-415
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• 2006

In recent years there has been considerable interest in the network GPS RTK surveying. Single RTK has some limit in long distance and it has an accuracy problem depend on the baseline length. The significant improvement of GPS network technology, RTCM V3.0 correction format and telecommunication technology can eliminate the weakness of single GPS RTK. This paper is the practical field result of GPS network RTK.

• 대한공간정보학회지
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• 제21권4호
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• pp.55-63
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• 2013

전통적인 RTK측량기술의 제약을 극복하고자 VRS 또는 FKP와 같은 네트워크 RTK GPS측량기술이 국가상시관측소와 무선인터넷망을 기반으로 개발되었다. 우리나라의 경우 국토지리정보원이 51개의 상시관측소와 모바일 인터넷망을 기반으로 네트워크 RTK를 서비스하고 있다. 본 연구에서는 이러한 Network-RTK 기반의 GNSS VRS 측량방식에 의한 표고정확도를 확인하고자 산청~진주지역의 1등 수준노선과 거창~산청지역의 2등 수준노선에 대하여 직접 GPS VRS 측량을 실시하고 그 결과를 분석하였다. 연구결과 GPS VRS측량방식의 표고 정확도는 1등 수준노선에서 2.15cm, 2등 수준노선에서 1.80cm로 나타났으며, 이러한 결과는 3,4등급 공공수준점측량에 있어서 GPS VRS 방식이 적용가능하다는 것과 아울러 이에 대한 작업규정이 필요하다는 것을 보여주는 것이다.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2003년도 춘계학술발표회 논문집
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• pp.55-60
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• 2003

As the distance between GPS rover station and GPS base station increases, more decorrelated positioning errors limit the ability for PDGPS(Precise Differential GPS). The objective of this paper is to present the improvement of using VRS(virtual reference station) based on multiple GPS reference station network to single reference station for static positioning in post-processing mode. For this, the VRS observations from GPS observations of real reference stations are derived by using Web service in post-mode. The coordinates of check point post-processed by 27 kind of VRS observations compared with the known ones.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2007년도 춘계학술발표회 논문집
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• pp.37-42
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• 2007

A network of MAC type was constructed in the Gyeonggi-do area to analyze the usefulness and validity of the Network RTK-GPS. Six sites were selected to conduct GPS observation for 24 hours, and by determining the ITRF of each site, coordinates were determined in connection with IGS network. Then check points which were established in Gimpo area were observed at least 7 times by Network RTK at 20 secs of retrieval intervals. The result showed high accuracy in the difference between the coordinates determined immediately by the in-field network survey and the current performance was 1-2cm. Its biggest benefit is the expanded range of survey and efficiency of practice. In summary, it is proved that a network survey has the accuracy, scalability and efficiency and it is expected that the network survey will contribute to the cadastral survey.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.117-122
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• 2006

Modernized GNSS such as new GPS signals updated GLONASS and coming Galileo promises higher quality and higher reliability for users. Powerful technologies such as Internet, ubiquitous network technology and sensor network has been used to promote a safe and more secure lifestyle. This report describes experimental trials to combine these technologies namely GPS and Sensor Network into a high-performance system. GPS is used to enlarge the communication range, resolving the service area limitations, as a wider service area is required at shore areas compared to urban area. GPS position datum is also used as primary network routing information to get practical Sensor Network. Another application is the under water Sensor Network. Accurate GPS position and time are used to establish stable and high reliability underwater acoustic Sensor Network. This paper describes the background of the project 'Harbor area Marine Ubiquitous Sensor Network', preliminary consideration and testing. Radio and acoustic communication is the main focus of this preliminary experiment.