• Journal of Positioning, Navigation, and Timing
• /
• v.12 no.3
• /
• pp.289-294
• /
• 2023

As technologies such as cameras, Laser Imaging, Detection, and Ranging (LiDAR), and Global Navigation Satellite Systems (GNSS) become more sophisticated and common, their use in autonomous driving technologies is being explored in various fields. In the maritime area, technologies related to collision avoidance between ships are being developed to evaluate and avoid the risk of collision between ships by setting various scenarios. However, the position of each vessel used in the process of developing collision avoidance technology between vessels uses data obtained through GNSS, and may include a position error of 10 m or more depending on the situation. In this paper, a study on the dynamic safety navigation range including the positional inaccuracy of the ship is conducted. By combining the concept of the protection level obtained using GNSS raw data with a conventional safe navigation range, a safer navigation range can be calculated for dynamic navigation. The calculated range is verified using data obtained while sailing in an actual sea environment.

• Journal of Navigation and Port Research
• /
• v.46 no.3
• /
• pp.158-167
• /
• 2022

The International Maritime Organization's e-Navigation strategy introduces new technologies to ships to support easier and safer navigation. To implement the e-Navigation strategy, it was necessary to develop a common data model, that could meet various requirements across all aspects of the maritime information service. The International Hydrographic Organization's S-100 Universal Hydrographic Data Model was selected, as the basis for the standardization of maritime data products. Three S-100 based product specifications for weather information, collectively called "S-41X", are currently under development by the NOAA's Ocean Prediction Center, for use in the Electronic Chart Display and Information System (ECDIS). This paper describes a design of a grid based S-413 data model out of three S-41X product specifications. Other S-100 data products, which support the gridded data format, were considered. To verify the data model, an encoding test was conducted, using the Korean Meteorological Adminstration's numerical prediction model results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2017.10a
• /
• pp.274-276
• /
• 2017

Korean e-Navigation is a system that introduced to reduce maritime accidents. In order to reduce marine accidents, Korean e-Navigation provides the following services-"Vulnerable Vessel Monitoring", "Vulnerable Vessel support & monitoring", "Optimal safety route", "ENC Streaming for Small Vessel", "Tug & Barge Support", "Maritime Safety Information Providing". Each Service is a system separated into finctional units and integrated into Korean e-Navigation. Korean e-Navigation is introducing data middleware to integrate each service and the DDS(Data Distribution Service) is judged to be effective. Thus, this paper analyzed the characteristics of DDS middleware types suitable for each service of e-Navigation.

• Journal of KIISE:Software and Applications
• /
• v.32 no.5
• /
• pp.416-427
• /
• 2005

Web navigation mining is a method of discovering Web navigation patterns by analyzing the Web access log data. However, it is admitted that the log data contains noisy information that leads to the incorrect recognition of user navigation path on the Web's hyperlink structure. As a result, previous Web navigation mining systems that exploited solely the log data have not shown good performance in discovering correct Web navigation patterns efficiently, mainly due to the complex pre-processing procedure. To resolve this problem, this paper proposes a technique of amalgamating the Web's hyperlink structure information with the Web access log data to discover navigation patterns correctly and efficiently. Our implemented Web navigation mining system called SPMiner produces a WebTree from the hyperlink structure of a Web site that is used trl eliminate the possible noises in the Web log data caused by the user's abnormal navigational activities. SPMiner remarkably reduces the pre-processing overhead by using the structure of the Web, and as a result, it could analyze the user's search patterns efficiently.

• Journal of Mechanical Science and Technology
• /
• v.19 no.8
• /
• pp.1529-1543
• /
• 2005

Recently an unmanned aerial vehicle (UAV) has been widely used for military and civil applications. The role of a navigation system in the UAV is to provide navigation data to the flight control computer (FCC) for guidance and control. Since performance of the FCC is highly reliant on the navigation data, a fault in the navigation system may lead to a disastrous failure of the whole UAV. Therefore, the navigation system should possess a fault detection and isolation (FDI) algorithm. This paper proposes an attitude determination GPS/INS integrated navigation system with an FDI algorithm for a UAV. Hardware for the proposed navigation system has been developed. The developed hardware comprises a commercial inertial measurement unit (IMU) and the integrated navigation package (INP) which includes an attitude determination GPS (ADGPS) receiver and a navigation computer unit (NCU). The navigation algorithm was implemented in a real-time operating system with a multi-tasking structure. To evaluate performance of the proposed navigation system, a flight test has been performed using a small aircraft. The test results show that the proposed navigation system can give accurate navigation results even in a high dynamic environment.

• Journal of Positioning, Navigation, and Timing
• /
• v.9 no.4
• /
• pp.305-317
• /
• 2020

The navigation message is composed of the information contained in the message and the structure for transmitting this information. In order to design a navigation message, considerations in terms of message content and message structure must be elicited. For designing a Korea Positioning System (KPS) navigation message, this paper explains performance indicators in terms of message structure and message content. Most of the performance analysis of GNSS navigation messages already in operation was performed only for Time-to-first-fix-Data (TTFFD). However, in the navigation message, the message content is composed of Clock-Ephemeris Data (CED) and additional information. So, this paper proposes a new performance indicator R_(Non-CED) that can be analyzed from the viewpoint of receiving additional information along with an explanation of TTFFD focusing on the CED reception time. This paper analyze the performance in terms of message structure using these two performance indicators. The message structures used for analysis are the packetized message protocol like GPS CNAV and the packetized and fixed pattern message protocol like GPS CNAV-2. From the results, it is possible to proffer how KPS navigation messages can have better performance than GPS navigation messages. And, these two performance indicators, TTFFD and R_Non-CED, can help to design the minimum TTFF required performance of KPS navigation messages.

• Journal of Positioning, Navigation, and Timing
• /
• v.12 no.4
• /
• pp.409-421
• /
• 2023

In order to develop navigation systems, simulators that provide navigation sensors data are required. A trajectory generator that simulates vehicle motion is needed to generate navigation sensors data in the simulator. In this paper, a trajectory generator for evaluating navigation system performance is proposed. The proposed trajectory generator consists of two parts. The first part obtains parameters from the motion scenario file whereas the second part generates position, velocity, and attitude from the parameters. In the proposed trajectory generator six degrees of freedom, halt, climb, turn, accel turn, spiral, combined, and waypoint motions are given as basic motions with parameters. These motions can be combined to generate complex trajectories of the vehicle. Maximum acceleration and jerk for linear motion and maximum angular acceleration and velocity for rotational motion are considered to generate trajectories. In order to show the usefulness of the proposed trajectory generator, trajectories were generated from motion scenario files and the results were observed. The results show that the proposed trajectory generator can accurately simulate complex vehicle motions that can be used to evaluate navigation system performance.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.9
• /
• pp.1409-1415
• /
• 2017

The navigation and EDR(Event Data Recorder) have a different roles but also a lot of similar or common functions and elements. A representative element is a GPS. The GPS of navigation is a more higher than the that of EDR in performance. The high performance GPS has a very short initialization time and more accurate than the GPS of EDR. And the informations of OBD(On Board Diagnostics) is able to be shared in navigation and EDR. But these inter-working product between the navigation and EDR has been not yet shown. So, this paper is aimed to show how to interwork in two devices. We utilize USB bulk communication in two devices for inter-working. It is very simple ways and it could interwork in GPS, event video and ODB II data. It could be effective in cost competence and convenience. These was implemented by hardware and software and proved by the standard test.

• Journal of Positioning, Navigation, and Timing
• /
• v.7 no.4
• /
• pp.285-294
• /
• 2018

In this study, we implemented the data quality monitoring algorithm which is the previous step for real-time Global Navigation Satellite System (GNSS) correction generation and compared Global Positioning System (GPS) and BeiDou System (BDS). Signal Quality Monitoring (SQM), Data QM, and Measurement QM (MQM) that are well known in Ground Based Augmentation System (GBAS) were used for quality monitoring. SQM and Carrier Acceleration Ramp Step Test (CARST) of MQM result were divided by satellite elevation angle and analyzed. The data which are judged as abnormal are removed and presented as Root Mean Square (RMS), standard deviation, average, maximum, and minimum value.

• Journal of Astronomy and Space Sciences
• /
• v.22 no.3
• /
• pp.243-248
• /
• 2005

NORAD Two Line Element (TLE) is very useful to simplify the ground station antenna pointing and mission operations. When a satellite operations facility has the capability to determine NORAD type TLE which is independent of NORAD, it is important to analyze the applicable tracking data arcs for obtaining the best possible orbit. The applicable tracking data arcs for NORAD independent TLE orbit determination of the KOMPSAT-1 using GPS navigation solutions was analyzed for the best possible orbit determination and propagation results. Data spans of the GPS navigation solutions from 1 day to 5 days were used for TLE orbit determination and the results were used as Initial orbit for SGP4 orbit propagation. The operational orbit determination results using KOMPSAT-1 Mission Analysis and Planning System(MAPS) were used as references for the comparisons. The best-matched orbit determination was obtained when 3 days of GPS navigation solutions were used. The resulting 4 days of orbit propagation results were within 2 km of the KOMPSAI-1 MAPS results.