• The KIPS Transactions:PartA
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• v.13A no.4 s.101
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• pp.335-342
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• 2006

As PRC linear interpolation algorithm is applied after analysed and verified in this paper, the unknown location of a user can be identified by using PRC information of multi-DGPS reference station. The PRC information of each GPS satellite is not varying rapidly, which makes it possible to assume that PRC information of each GPS satellite varies linearly. So, the PRC regeneration algorithm with linear interpolation can be applied to improve the accuracy of finding a user's location by using the various PRC information obtained from multi-DGPS reference station. The desirable PRC is made by the linear combination with the known position of multi-DGPS reference station and PRC values of a satellite using signals from multi-DGPS reference station. The RTK-GPS result was used as the reference. To test the performance of the linearly interpolated PRC regeneration algorithm, multi-channel DGPS beacon receiver was built to get a user's position more exactly by using PRC data of maritime DGPS reference station in RTCM format. At the end of this paper, the result of the quantitative analysis of the developed navigation algorithm performance is presented.

• 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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2073-2078
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• 2014

Based on the DGPS radio wave measurement in the coast of the yellow-sea, south-sea and east-sea, the DGPS service regions in the korean coastal ferry route are analyzed in this paper. The impact of obstacles on the propagation due to the archipelago and island regions are measured and analyzed in the point of service region. The ocean-based DGPS reference stations provide the wide DGPS ocean service regions with signal strength more than $40dB{\mu}V/m$ and signal-to-noise ratio more than 10 dB. Based on the overlapping of the service regions between the DGPS reference stations, the DGPS services with good quality are provided in the coastal ferry route segments. In case of regions where the propagation obstacles are scattered, the increasingly good service can be provided under conditions of output power reinforcement and antenna efficiency enhancement.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.206-207
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• 2005

해상에서 인터넷을 사용하는 데 많은 기술적, 경제적 제약이 따른다. 육상의 인터넷 서비스를 바다 위에서 실현하기 위해서는 기지국과 같은 중앙 통제 시스템이 없는 MANET을 기반으로 하는 해상통신망이 새롭게 구축되어야 한다. 본 논문에서는 해상환경과 선박 내 단말장치의 특성을 최대한 고려한 해상 MANET 모델을 새롭게 설계하였다. 원양에서 선박들이 주로 주어진 항로를 기준으로 항해하는 특성을 고려하여, 개별적 이동노드(선박)를 대상으로 경로를 찾는 것이 아니라 정적 정보인 항로와 동적 정보인 선박을 복합적으로 활용하여 최단경로를 찾아내는 복합적 항로기반 라우팅(HCBR) 프로토콜을 제안하였다. 지리 정보를 이용하는 LAR 프로토콜과 성능 비교에서 경로 발견 시 제어패킷을 전혀 쓰지 않으면서 최단 경로를 훨씬 더 잘 찾아내는 특성을 실험적으로 파악하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.5
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• pp.572-579
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• 2008

To predict the system coverage in the middle frequency(MF) band, it is required to know the antenna efficiency at a base station. However, calculating the accurate efficiency is difficult since the efficiency may change according to the area where the antenna is installed. Thus, this paper proposes a method to obtain the antenna efficiency of a base station in the MF band from the measurement. This method uses the measured field strengths and the attenuation model in the MF band. Therefore, an attenuation model which is used in the proposed method is presented at first. Then, the process of the proposed method is followed using detailed explanations. Finally, antenna efficiencies of base stations which are currently operating are obtained by applying the proposed method and the usefulness of the obtained results are verified by comparing with ideal efficiencies.

• Journal of Korea Port Economic Association
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• v.35 no.4
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• pp.85-106
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• 2019

Offshore wind power is a representative renewable energy source and a rapidly growing industry. In Gyeongsangnam-do, offshore wind farms of 461.9MW are being pushed for in the Yokji island and are expected to expand further to over 1GW in the future. Accordingly, ports supporting the storage, assembly, transportation, and installation of offshore wind power equipment are expected to play an important role in the smooth progress of the offshore wind farm development project. Based on previous research and cases in major countries,this study prepared criteria for assessment of ports supporting offshore wind farmsand evaluated ports in Gyeongsangnam-do, which are linked to Yokji island offshore wind farms. The assessment criteria have been subdivided into distance from the offshore wind farm, port entry and exit restrictions, navigational areas, fishery rights factors, additional costs, berth length, depth of berth, size of the port yard, port berth bearing pressure, interference with other cargo, a civil appeal, and relevant industrial aggregation. The ports of Tongyeong, Samcheonpo, Kohyun, Masan, and Jinhae in Gyeongsangnam-do were selected and evaluated. As a result, the port of Tongyoung was superior in terms of distance from the Yokji island offshore wind farm. The ports of Samcheonpo, Masan, and Jinhae were evaluated as excellent in other criteria such as berth length, depth of berth, and so on. This study is expected to be used as a source of basic data for offshore wind power companies and policymakers to select and evaluate the supporting ports of offshore wind farms.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.3
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• pp.181-189
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• 2002

This paper describes the positioning accuracies for single and multiple reference stations at fixed stations in Yosu harbor and Pukyong National University in the south coast of Korea from Jan. to Oct. 2001. Also we observed the change of positioning accuracy during a day and the available range of the DGPS reference station. he results obtained are main summarized as follows; 1. With single DGPS reference station, 2drms and the average positioning .error were 5.6m, 7.3m respectively. Measurement positions indicated an incline toward one way away from the actual position. 2. With multiple DGPS reference stations, 2drms and the average position error were 5.5m, 3.2m for the arithmetic mean, respectively. They were 5.3m, 3.8m for the weighted average, respectively. As far as the separation between the user and the reference station, using multiple reference stations improved position accuracy more than using single reference station. 3. The average positioning error increased between 16: 00 and 22 : 00. The average number of observed satellite and HDOP were 7.1m, 0.49 respectively. 4. Coverage of DGPS reference stations in the south coast of Korea was estimated to be 110nm. Signal strength and signal to noise ratio was not available the DGPS signal below 19㏈, 8㏈ respectively.

• Journal of Navigation and Port Research
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• v.43 no.6
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• pp.429-436
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• 2019

The eLoran system is considered the best alternative because the vulnerability of satellite navigation systems cannot be resolved as perfect. Thus, South Korea is in the process of establishing a testbed of the eLoran system in the West Sea. To provide resilient navigation services to all waters, additional eLoran transmitters are required. However, it is difficult to establish eLoran transmitters because of various practical reasons. Instead, the positioning with NDGNSS/AIS source can expand the coverage and its algorithm with applying continuous waves is under development. Using the already operating NDGNSS reference station and the AIS base station, it is possible to operate the navigation system with higher accuracy than before. Thus, it is crucial to predict the performance when each system is integrated. In this paper, we have developed a simulation tool that can predict the performance of terrestrial integrated navigation system using the eLoran system, maritime NDGNSS station and the AIS station. The esitmated phase error of the received signal is calculated with the Cramer-Rao Lower Bound factoring the transmission power and the atmospheric noise according to the transmission frequency distributed by the ITU. Additionally, the simulation results are more accurate by estimating the annual mean atmospheric noise of the 300 kHz signal through the DGPS signal information collected from the maritime NDGNSS station. This approach can further increase the reliability of simulation results.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.2
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• pp.402-408
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• 2021

GNSS-Reflectometry (GNSS-R) is a technique for measuring and analyzing signals transmitted from satellites, reflecting on the surface of land or sea. GNSS-R is mainly used for measuring the water level variation, typhoon and meteorological anomaly, soil moisture, and snow depth. This paper describes the concept and measurement principle of GNSS-R technology, especially focusing on the field of marine utilization and its feasibility. In particular, it presents the applications of this technique for monitoring the safety of marine environment as well as the marine vessel and their utilization areas based on currently available infrastructure on the ground and maritime reference stations, such as the existing differential GNSS reference stations and integrity monitors (DGNSS RSIM), and GNSS reference station infrastructure, using the ground-based and the satellite-based GNSS-R approaches.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2010.10a
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• pp.4-6
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• 2010

지상파 항법인 로란은 전송된 신호는 장파특성에 따라 지표파에 의한 정보를 전달하게 되는데 지표면과 해수면의 특성 즉, 전도도에 따라 전파의 지연시간이 달라진다. 이것은 정확도를 저하시키는 원인이 된다. 그러므로 보다 정확도가 요구되는 지역에서는 전파지연에 의해 발생하는 시간적 공간전 변화(ASF)를 보상하게 되면 정확도를 향상시킬 수 있다. 로란시스템의 현대화와 eLoran 시스템에서는 ASF를 보상함으로써 선박이 항만으로 진입 및 접안할 때 활용할 수 있는 정확도 기준을 마련하고 있다. 이 조건을 충족시키기 위해서는 ASF의 정밀측정 필수이며, 본 논문에서는 포항송신국 근해인 영일만 해상에서 ASF를 실측한 결과와 그에 필요한 측정기술을 보고한다.