• Journal of Positioning, Navigation, and Timing
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• 제12권3호
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• pp.289-294
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• 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.

• 한국항해항만학회지
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• 제46권3호
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• pp.158-167
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• 2022

국제해사기구의 e-Navigation 전략은 선박에 새로운 기술을 도입하여 더욱 편리하고 안전한 항해를 지원하는 것이다. e-Navigation 전략 이행을 위해 다양한 해양 정보 서비스에서 발생 가능한 요구사항을 수용할 수 있는 공통 데이터 모델이 필요하게 되었고, 최종적으로 국제수로기구의 S-100 표준이 선정되었다. 이 중 해양기상정보를 차세대 전자해도정보시스템에서 표출하기 위한 S-41X 제품표준은 현재 개발이 미 완료된 시점이다. 본 논문은 S-41X 제품표준 중 격자 데이터 기반의 S-413 제품에 대한 데이터 모델을 설계하였다. 또한 격자 데이터 형식을 지원하는 타 S-100 데이터 제품을 참고하여 국내 원시자료인 기상청 수치예보모델 결과를 활용한 제품 인코딩 테스트 단계의 연구를 수행하였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 추계학술대회
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• pp.274-276
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• 2017

한국형 e-Navigation은 해양사고를 줄이기 위해서 도입하고 있는 체계로, 선박 운항기술에 정보통신 기술을 융합하고 있다. 해양사고를 줄이기 위해 한국형 e-Navigation은 "사고취약선박 모니터링", "사고취약선박 선내지원 모니터링", "최적안전항로 지원", "소형선박용 전자해도 스트리밍", "도선 및 예선 지원", "해양 안전정보 제공"과 같은 서비스를 제공한다. 각 서비스는 기능단위로 분리된 별도의 시스템이며, 전체가 통합되어 한국형 e-Navigation을 구성하게 된다. 각 서비스를 유기적으로 연결하고 원활한 데이터 통신이 가능토록 하기 위해 데이터 미들웨어를 도입하고 있으며, 그중 효과적이라 판단되고 있는 것은 DDS(Data Distribution Service)이다. 이에 본 논문에서는 한국형 e-Navigation에 적용하기 위해서 DDS 미들웨어가 필수적으로 제공해야 하는 기능 및 특징을 분석하였다.

• 한국정보과학회논문지:소프트웨어및응용
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• 제32권5호
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• pp.416-427
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• 2005

웹 네비게이션 마이닝은 웹 접근 로그 데이타를 분석하여 웹을 항해하는 패턴을 발견하는 기법이다. 하지만 사용자들은 웹을 항해할 때 정상적인 계층적 경로를 따르지 않는 경우가 많기 때문에 웹 접근 로그 데이타에는 웹 항해 패턴 발견에 장애가 되는 잡음 정보가 많이 포함된다. 결과적으로 웹 접근 로그 데이타만을 이용한 기존의 웹 네비게이션 마이닝은 이런 잡음을 해결하기 위한 전처리 과정의 복잡성 등으로 인하여 웹 항해 패턴을 효율적으로 발견하는 데 좋은 성능을 보여주지 못했다. 이런 문제를 해결하기 위해 본 논문에서는 웹 접근 로그 데이타 외에 웹의 하이퍼링크 구조 정보를 함께 이용하여 웹 네비게이션 패턴을 효율적으로 발견하는 기법을 제시하였다. 웹 사이트의 계층적인 하이퍼링크 구조로부터 생성된 WebTree라 불리는 구조를 이용하여 웹 접근 로그 데이타에 포함된 비정상적인 경로에 대한 잡음을 효율적으로 제거하였다. 이 기법을 이용해 구현된 SPMiner(Sequence Pattern Miner) 시스템은 로그 데이타와 하이퍼링크 계층구조를 함께 이용함으로써 전처리의 오버헤드를 현저히 감소시켰고 결과적으로 효율적으로 네비게이션 패턴을 찾아주고 이를 추천에 이용할 수 있는 기반을 제시하였다.

• Journal of Mechanical Science and Technology
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• 제19권8호
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• pp.1529-1543
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• 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
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• 제9권4호
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• pp.305-317
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• 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
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• 제12권4호
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• pp.409-421
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• 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.

• 전기학회논문지
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• 제66권9호
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• pp.1409-1415
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• 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
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• 제7권4호
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• pp.285-294
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• 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
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• 제22권3호
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• pp.243-248
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• 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.