• Journal of Positioning, Navigation, and Timing
• /
• v.10 no.4
• /
• pp.271-278
• /
• 2021

In this paper, a tropospheric delay error was calculated by using meteorological data collect from weather station and Saastamoinen model, and an empirical variogram of the tropospheric delay in the Korean peninsula was estimated. In order to estimate the empirical variogram of the tropospheric delay according to weather condition, sunny day, rainy day, and typhoon day were selected as analysis days. Analysis results show that a maximum correlation range of the empirical variogram on sunny day was about 560 km because there is overall trend of the tropospheric delay. On the other hand, the maximum correlation range of the empirical variogram on rainy was about 150 km because the regional variation was large. Although there is regional variation when the typhoon exists, there is a trend of the tropospheric delay due to a movement of the typhoon. Therefore, the maximum correlation range of the empirical variogram on typhoon day was about 280 km which is between sunny and rainy day.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2013.10a
• /
• pp.427-428
• /
• 2013

The Lighthouses and light beacons are representative structures of Aids to Navigation(AtoN) facilities. Incheon had been the region where they were constructed actively in early moden era. This study is targeting the lighthouse and light beacon which are managed by Regional Maritime Affairs. They will be organized by the research from field investigation. And conservation and management method for long-term preservation on the objects that has cultural and historical values will be suggested through this study.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• v.1
• /
• pp.417-421
• /
• 2006

ICAO defines performance requirements of navigation system such as accuracy, integrity, continuity and availability. The integrity is most significant performance requirement in aviation where safety of life is crucial. Many researches on this topic anticipate that GPS with SBAS or Galileo can meet APV requirements and GPS with GBAS or Galileo with GBAS will meet CAT II and III requirements. These performance expectations are based on global analysis. In this paper regional integrity analysis in Korea using various combinations of modernized GPS, Galileo and SBAS is given. The simulation results show that CAT I requirement can be met using modernized GPS and Galileo alone, however, CAT II and III are not met even augmenting SBAS because of VPL. A more efficient augmentation such as GBAS which can reduce VPL dramatically is required to meet CAT II and III in Korean region.

• Journal of Positioning, Navigation, and Timing
• /
• v.13 no.2
• /
• pp.159-165
• /
• 2024

The Global Navigation Satellite System (GNSS) has been used as a tool to accurately extract the Total Electron Content (TEC) in the ionosphere. The multi-GNSS (GPS, GLONASS, BeiDou, Galileo, and QZSS) constellations bring new opportunities for ionospheric research. In this study, we develop a regional ionospheric TEC model using GPS, Galileo, and QZSS measurements. To develop an ionospheric model covering the Asia-Oceania region, we select 13 International GNSS Service (IGS) stations. The ionospheric model applies the spherical harmonic expansion method and has a spatial resolution of 2.5°×2.5° and a temporal resolution of one hour. GPS TEC, Galileo TEC, and QZSS TEC are investigated from January 1 to January 31, 2024. Different TEC values are in good agreement with each other. In addition, we compare the QZSS(J07) TEC and the Center for Orbit Determination in Europe (CODE) Global Ionosphere Map (GIM) TEC. The results show that the QZSS TEC estimated in the study coincides closely with the CODE GIM TEC.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2013.10a
• /
• pp.204-205
• /
• 2013

VTS service results from VTS watchman's mind as all other human conducts. Psychological motivations are divided into 4 factors ; collective unconscious, fear, responsibility, humanity. These motivations are beginning of VTS. Motivations awaken watchman and effect all other steps of service. Out of these motivations, higher factors ; responsibility and humanity act very positively and can be best solution for safety of vessel traffic ; the purpose of coastal VTS. Therefore, VTS officers should be educated to build up these virtues in their mind.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2000.08a
• /
• pp.173-181
• /
• 2000

Lockheed Martin has integrated and installed numerous AIS systems around the world as part of several VTS installation contracts and technology demonstrations for customers. Each of these systems incorporates specific customer requirements addressing differing objectives. This paper describes the capabilities and features of Lockheed Martin's current implementation of the Universal AIS system, and the experiences Lockheed Martin has had with earlier AIS and ADS (automated dependent surveillance) system installations. Specific examples are provided for an amphibious landing exercise with the US Army; installations at a Middle-East Oil port; technology demonstrations in New York Harbor, USA; river systems in New Orleans, Louisiana, USA; and coastal applications in the Gulf of Suez. The paper closes a brief overview of the most recent activity, the Turkish Straits VTMIS project that requires Universal AIS installations. The evolution of the technology and lessons learned will be discussed in the context of these examples. The perspective will be on Lockheed Martin's experience working with different customers to integrate AIS technology into a larger VTS or Port Information System. It will also discuss, from the practical side, how AIS information is used by a variety of maritime organizations with differing needs and information objectives.

• Journal of Positioning, Navigation, and Timing
• /
• v.13 no.1
• /
• pp.63-73
• /
• 2024

NeQuick G is the ionosphere model utilized by Galileo single-frequency users to estimate the ionospheric delay on each user-satellite link. The model is characterized by the effective ionization level (Az) index, determined by a modified dip latitude (MODIP) and broadcast coefficients derived from daily global space weather observations. However, globally fitted Az coefficients may not accurately represent ionosphere within local area. This study introduces a method for regional ionospheric modeling that searches for locally optimized Az coefficients. This approach involves fitting TEC output from NeQuick G to TEC data collected from GNSS stations around Korea under various ionospheric conditions including different seasons and both low and high solar activity phases. The optimized Az coefficients enable calculation of the Az index at any position within a region of interest, accounting for the spatial variability of the Az index in a polynomial function of MODIP. The results reveal reduced TEC estimation errors, particularly during high solar activity, with a maximum reduction in the RMS error by 85.95%. This indicates that the proposed method for NeQuick G can effectively model various ionospheric conditions in local areas, offering potential applications in GNSS performance analyses for local areas by generating various ionospheric scenarios.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.39 no.3
• /
• pp.1-9
• /
• 2016

NSS (Navigation satellite system) provides the information for determining the position, velocity and time of users in real time using satellite-networking, and is classified into GNSS (Global NSS) and RNSS (Regional NSS). Although GNSS services for global users, the exactitude of provided information is dissatisfied with the degree required in modern systems such as unmanned system, autonomous navigation system for aircraft, ship and others, air-traffic control system. Especially, due to concern about the monopoly status of the countries operating it, some other countries have already considered establishing RNSS. The RNSS services for users within a specific area, however, it not only gives more precise information than those from GNSS, but also can be operated independently from the NSS of other countries. Thus, for Korean RNSS, this paper suggests the methodology to design the satellite constellation considering the regional features of Korean Peninsula. It intends to determine the orbits and the arrangement of navigation satellites for minimizing PDOP (Position dilution of precision). PGA (Parallel Genetic Algorithm) geared to solve this nonlinear optimization problem is proposed and STK (System tool kit) software is used for simulating their space flight. The PGA is composed of several GAs and iterates the process that they search the solution for a problem during the pre-specified generations, and then mutually exchange the superior solutions investigated by each GA. Numerical experiments were performed with increasing from four to seven satellites for Korean RNSS. When the RNSS was established by seven satellites, the time ratio that PDOP was measured to less than 5 (i.e. better than 'Good' level on the meaning of the PDOP value) was found to 94.3% and PDOP was always kept at 10 or less (i.e. better than 'Moderate' level).

• Journal of Navigation and Port Research
• /
• v.32 no.1
• /
• pp.73-80
• /
• 2008

The purpose of this paper is to measure the productive efficiency and competitive strength of Regional Maritime Affairs and Fisheries Office using the DEA. Using EMS(Efficiency Measurement System) which is LP solver, quantifies in one way or another a "distance" to the efficient frontier of the technology. An input oriented measure quantifies the input reduction which is necessary to become efficient holding the output constant. Symmetrically, an output oriented measure quantifies the necessary to become efficient holding the inputs constant. A non-oriented measure quantifies necessary improvements when both inputs and outputs can be improved simultaneously. According to the analysis result of the DEA method, inefficient Regional Maritime Affairs and Fisheries Office should recommend benchmarking reference Regional Maritime Affairs and Fisheries Office in order to enhance the productive efficiency of port administration and a public institution. Besides data on productive efficiency serves as a tool for policy-makers at all levels of activity and is essential for improving the efficiency with which the various systems operate.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2009.06a
• /
• pp.397-401
• /
• 2009

On the crisis of international economy, the government is making an effort to seek economic growing motivation with the method of overcoming economic crisis and 'low carbon green growth'. Furthermore, to promote maritime vessel traffic service related inefficient energy wastage was revealed and eco-friendly alternative energy was accepted because of high price of oil in the beginning of 2008. In this situation, I'm going to discuss the possibility of eco-friendly energy system in maritime vessel traffic service with the way of cutting the budget and expansion of solar power generation system which was promoted to meet governmental 'energy saving plan for high price of oil'.