• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.40 no.3
• /
• pp.308-315
• /
• 1991

This paper deals with the global dynamic behavior of multiple autonomous mobile robots with suggested navigation strategies within unbounded and bounded spatial domain. We derive some navigation strategies of robots wirh complete detectability with finite range to reach their goal states without collision which is motivated by Coulomb's law regarding repulsive and attractive forces between electrical charges. An analysis of the dynamic behavior of the interacting robots with the suggested navigation strategies under the assumption that communication is not permissible between robots is made and some examples are illustrated by computer simulation. The convergence of robot motions to their goal states under certain conditions is established by considering their global dynamic behavior even when some objects are close to their goal points.

• Journal of Fisheries and Marine Sciences Education
• /
• v.6 no.2
• /
• pp.198-216
• /
• 1994

The problem of promoting instructional effect using reorganizing the content of textbook is one of the major concerns of many education theorists and teachers. The results of many researches about above problem reveal that reorganizing the content of textbook promotes the ability of recall and problem solving of learners. The content structure of current navigation textbook revealed a categorical structure as its basic framework, though it seems to be a poor one. A categorical structure is known as providing an inferior information processing mechanism for learners than a learning hierarchy content structure is. Furthermore current content structure hasn't given any considerations to navigation in practice, spatial contexts and sequential events of ships from a harbor to another harbor. The learning hierarchy content structure has an advantage of giving learners more systematic and stronger knowledge networks than a categorical structure.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.6 no.4
• /
• pp.314-320
• /
• 2006

Navigation in environments that are densely cluttered with obstacles is still a challenge for Autonomous Ground Vehicles (AGVs), especially when the configuration of obstacles is not known a priori. Reactive local navigation schemes that tightly couple the robot actions to the sensor information have proved to be effective in these environments, and because of the environmental uncertainties, STSF(Space and Time Sensor Fusion)-based fuzzy behavior systems have been proposed. Realization of autonomous behavior in mobile robots, using STSF control based on spatial data fusion, requires formulation of rules which are collectively responsible for necessary levels of intelligence. This collection of rules can be conveniently decomposed and efficiently implemented as a hierarchy of fuzzy-behaviors. This paper describes how this can be done using a behavior-based architecture. The approach is motivated by ethological models which suggest hierarchical organizations of behavior. Experimental results show that the proposed method can smoothly and effectively guide a robot through cluttered environments such as dense forests.

• Journal of Positioning, Navigation, and Timing
• /
• v.9 no.4
• /
• pp.367-378
• /
• 2020

This paper introduces the development of the iterative multiple signal classification (MUSIC)-based direction-of-arrival (DOA) estimation system using a rotator that can control the direction of antenna for the global navigation satellite system (GNSS) interference. The system calculates the spatial spectrum according to the noise eigenvector of all dimensions to measure the number of signals (NOS). Also, to detect the false peak, the system adjusts the array antenna's direction and checks the change's peak angles. The phase delay and gain correction values for system calibration are calculated in consideration of the chamber's structure and the characteristics of radio waves. The developed system estimated DOAs of interferences located about 1km away. The field test results show that the developed system can estimate the DOA without NOS information and detect the false peak even though the inter-element spacing is longer than the half-wavelength of the interference.

• Journal of Korean Society for Geospatial Information Science
• /
• v.2 no.2 s.4
• /
• pp.109-115
• /
• 1994

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.36 no.5
• /
• pp.319-333
• /
• 2018

As human beings spend more time indoors, and with the growing complexity of indoor spaces, more focus is given to indoor spatial applications and services. 3D topological networks are used for various spatial applications that involve navigation indoors such as emergency evacuation, indoor positioning, and visualization. Manually generating indoor network data is impractical and prone to errors, yet current methods in automation need expensive sensors or datasets that are difficult and expensive to obtain and process. In this research, a methodology for semi-automatically generating a 3D indoor topological model based on IndoorGML (Indoor Geographic Markup Language) is proposed. The concept of Shooting Point is defined to accommodate the usage of omnidirectional images in generating IndoorGML data. Omnidirectional images were captured at selected Shooting Points in the building using a fisheye camera lens and rotator and indoor spaces are then identified using image processing implemented in Python. Relative positions of spaces obtained from CAD (Computer-Assisted Drawing) were used to generate 3D node-relation graphs representing adjacency, connectivity, and accessibility in the study area. Subspacing is performed to more accurately depict large indoor spaces and actual pedestrian movement. Since the images provide very realistic visualization, the topological relationships were used to link them to produce an indoor virtual tour.

• Journal of Navigation and Port Research
• /
• v.34 no.7
• /
• pp.567-575
• /
• 2010

Ningbo Port develops quickly in recent years and with the combination of Ningbo Port and Zhoushan Port, it becomes another important port in the Shanghai International Shipping center. Competition between the two biggest ports in this area can't be avoided. The goal of this paper is investigating the competence of port from two angles, which are spatial structure of the ports cluster and neighboring ports' attraction to cargoes at conjunct hinterlands. The paper firstly uses the HHI index model and shift-share method to qualitatively and quantitatively analyze the data of container throughputs of ports in the shipping center, in order that investigates the spatial structure of ports cluster. Basing on above researches, the paper employs the location quotient to study Shanghai port and Ningbo port's hinterland distributions at Zhejiang province. The conclusion of this study:(I)the ports cluster of the Shanghai International Shipping Center is highly centralized, and undergoes a porcess of first centralization then decentralization since the mid of 90s, last century. (2)Hinterlands of Shanghai port includes: Hangzhou, Jiaxing, Huzhou and Quzhou districts; Hinterlands of Ningbo port includes: Ningbo, Taizhou and Zhoushan districts.

• Journal of Advanced Navigation Technology
• /
• v.2 no.2
• /
• pp.126-131
• /
• 1998

In optical scanning holography, 3-D holographic information of an object is generated by 2-D active optical scanning. The optical scanning beam can be a time-dependent Gaussian apodized Fresnel zone plate. In this technique, the holographic information manifests itself as an electrical signal which can be sent to an electron-beam-addressed spatial light modulator for coherent image reconstruction. This technique can be applied to 3-D optical remote sensing especially for identifying flying objects. In this paper, we first briefly review optical scanning holography and analyze the resolution achievable with the system. We then present mathematical expression of real and virtual image which are responsible for holographic image reconstruction by using Gaussian beam profile.

• Journal of Korea Spatial Information System Society
• /
• v.10 no.2
• /
• pp.35-48
• /
• 2008

In this paper, we propose a Dynamic Heuristic to reduce the number of node accesses and improve quality of path in the client-based navigation service. The Dynamic Heuristic is to use heuristic data from server that is calculated with traffic data. The server-based navigation service provides a path searched on server and transmits it to client, but we propose that server only provide heuristic data to client. The proposed client searches a path with heuristic transmitted data from server. We present a new algorithm for using Dynamic Heuristic in the path-finding. The algorithm bases Grid Based Path-Finding, and has minimum speed data of edges in grid. It removes several grids whose minimum speed is less than limited speed.

• Journal of Navigation and Port Research
• /
• v.36 no.7
• /
• pp.545-552
• /
• 2012

Domestic marina facilities today consist mostly of composite-type marinas with particular spatial composition characteristics, due to the regulatory restrictions that keep their development in the public sector and the tepid growth of marine leisure-sports. To develop a marina club design appropriate for domestic conditions, this study establishes space program standards for designing Korean marinas based on a case analysis of existing marina clubs and a survey of floating marina clubs. It is possible for a current composite-type Korean marina club to have a spatial composition of 16~18% for marina-exclusive facility (mFA), 47~49% for commercial facility (cFA), 27~30% for public space (pFA) and 5~8% for management space (emFA). With this composition as a basis, space program estimation of a Korean marina club can be done through the process of estimating in order the marina-exclusive facility area, the floor area by each space and the total floor area, the first floor area, the deck area and the pontoon area. Since the space program established in this study can be utilized as a tool for designing a Korean marina club, it is expected to be helpful in designing marina clubs in the future.