• 한국항행학회논문지
• /
• 제15권4호
• /
• pp.495-501
• /
• 2011

GPS 수신기의 신호 추적 루프에서 추적 오차를 추정하는 판별기(Discriminator)의 특성은 잡음 전력에 의해 영향을 받으며, 실제로 판별기 함수의 기울기는 잡음 전력이 커질수록 작아지는 특성을 보인다. 본 논문에서는 추정한 C/N0를 이용하여 작아진 기울기를 보상할 수 있는 방법을 연구하였으며, GPS 수신기의 신호 추적 루프중에서 측위 성능에 직접적인 영향을 주는 코드 추적 루프에 적용함으로써 일반적인 판별기보다 더 정확한 추적 오차를 가지는 코드 추적 루프 설계 기법을 제안한다. 또한 모의실험 결과로부터 20g/s의 기동을 갖는 항체에 대하여 제안한 코드 추적 루프의 정확도가 약 50% 개선되는 것을 확인하였다.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• 제15권1호
• /
• pp.12-19
• /
• 2015

In order to guide the robots move along a collision-free path efficiently and reach the goal position quickly in the unknown multi-obstacle environment, this paper presented the navigation problem of a wheel mobile robot based on proximity sensors by fuzzy logic controller. Then a genetic algorithm was applied to optimize the membership function of input and output variables and the rule base of the fuzzy controller. Here the environment is unknown for the robot and contains various types of obstacles. The robot should detect the surrounding information by its own sensors only. For the special condition of path deadlock problem, a wall following method named angle compensation method was also developed here. The simulation results showed a good performance for navigation problem of mobile robots.

• 한국정밀공학회지
• /
• 제20권11호
• /
• pp.79-90
• /
• 2003

In this paper, we propose a multisensor-based navigation algorithm for a mobile robot, which is intelligently searching the goal location in unknown dynamic environments using multi-ultrasonic sensor. Instead of using “sensor fusion” method which generates the trajectory of a robot based upon the environment model and sensory data, “command fusion” method by fuzzy inference is used to govern the robot motions. The major factors for robot navigation are represented as a cost function. Using the data of the robot states and the environment, the weight value of each factor using fuzzy inference is determined for an optimal trajectory in dynamic environments. For the evaluation of the proposed algorithm, we performed simulations in PC as well as experiments with IRL-2002. The results show that the proposed algorithm is apt to identify obstacles in unknown environments to guide the robot to the goal location safely.

• Journal of Positioning, Navigation, and Timing
• /
• 제8권4호
• /
• pp.225-232
• /
• 2019

The satellite-based ionospheric model consists of local first-order plane function parameters for individual satellites and provides excellent accuracy in the flat ionospheric environment of the Korean Peninsula. This paper analyzes the performance of such model under the rapid changes in the ionosphere. Rapid changes in the ionosphere were observed in Korea from September to October 2014, and a satellite-based ionosphere model was applied to Wide Area Differential GPS (WADGPS) to analyze the navigation performance and the performance of estimating ionospheric delay errors. After processing the test data, it was confirmed that there was a deterioration in navigation performance and extrapolation performance in low-latitude areas and analyzed the cause.

• 제어로봇시스템학회논문지
• /
• 제15권4호
• /
• pp.385-389
• /
• 2009

This paper deals with the enhancement of the complex potential navigation for wheeled mobile robots. The circle theorem from complex function theory is used to avoid an obstacle, and the enhancement to avoid multiple obstacles is proposed. The limit cycle navigation can be combined for robot to kick the ball to the intentioned direction. Avoiding step and superposing twin vortices can be applied to adjust the direction of robot's trajectory. The proposed method is verified through a set of simulation works, and the feasibilities for the enhancement of complex potential theory are successful.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2004년도 Asia Navigation Conference
• /
• pp.163-166
• /
• 2004

Integrated Ship-Shore Information System makes use of advanced technology of marine mobile communication and extends the computer network of shipping company to ship. This system conveniently accomplishes the information exchange between company and ship, guarantees navigation safety and improves commercial performance. The framework of integrated ship-shore information system and the analysis of its function are provided in this paper. Meanwhile, the idea based on the specification of J2EE to build this system is put forward and the relevant technology is demonstrated.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2018년도 추계학술대회
• /
• pp.78-80
• /
• 2018

해상교통 환경변화에 부응하고 나아가 대형 해양사고 방지와 인명사고 예방을 위해 구축한 해양기상신호표지시스템을 기능 개선과 표준화된 설치 방법을 통해 표준화된 통합항로표지 관리운영시스템으로 운영하여 항로표지 유지관리에 있어서 효율적인 관리를 통해 해상교통 안전에 만전을 기하고자 한다.

• 지식경영연구
• /
• 제13권1호
• /
• pp.1-12
• /
• 2012

A knowledge map is a network-typed diagram visualizing all kinds of knowledge that influences each other to solve a problem. A knowledge map determines the structure of knowledge categorizing and archiving by defining the relationship of referential navigation among knowledge. Since tremendous and increasing number of knowledge needs to be included in a knowledge map, a knowledge map must be organized automatically by considering the contents and relationships of knowledge. This paper suggests the concept and prototype of a semi-automated knowledge map which automatically maps new piece of knowledge onto a manually provided draft map. The prototype knowledge map is based on the recursive programming to make a knowledge map automatically determine the location of the newly-entered knowledge by considering the referential relationship between knowledge. The proposed knowledge enables the knowledge network to expand autonomously by automatically including and storing knowledge. Also, it can improve the accuracy and applicability of knowledge for problem-solving, because the relationship of referential navigation among knowledge can be efficiently and effectively expressed.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2019년도 춘계학술대회
• /
• pp.40-41
• /
• 2019

VTS 관제에서 시스템적 환경은 선박의 트래픽 이동 및 주변 상황 인지가 매우중요하다. 즉, VTS 에서 도선예정 선박의 정보와, 스케줄의 내용을 파악하여야하며, 정박된 선박의 출항 도선을 하는 경우, 해당정보는 관제사가 파악하고 있어야 하는 정보이다. 따라서 본 논문에서는 도선 스케줄을 VTS 시스템에 적용, 관제사가 쉽게 이해 처리될 수 있도록 구조로 설계 및 구현하였다. 이러한 정보는 향후 e-Navigation 연계 등 관제시스템의 진화시에 실시간 정보교환하여 관제에 도움을 주는 부가 기능으로 제공, 예측관제에 활용될 수 있다.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제12권1호
• /
• pp.129-145
• /
• 2020

The article presents a systematic approach to design of marine navigation channels parameters resulting from manoeuvring and operational safety. Relations between the parameters of waterway system elements and the conditions of safe ship operation have been determined and the objective function of waterway parameters' optimization problems has been minimized with respect to variables of construction and operation costs. These costs have been functionally associated to variables of channel width at the bottom and fairway depth. The method of fairway's width computation at specified safe depth at the preliminary and detailed stages of waterway design has been proposed. The results of this method application have been illustrated with two examples: 1. The modernization of Szczecin-Swinoujscie fairway aimed at accepting vessels of 60,000 DWT capacity. 2. Construction of an approach channel leading to a newly built container terminal in Swinoujscie harbour (Poland), handling ocean-going container ships of 20,000 TEU capacity.