• Journal of the Korean Society of Marine Environment & Safety
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• v.10 no.1 s.20
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• pp.1-7
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• 2004

RADARSAT is one of many possible data sources that can play an important role in marine surveillance including ship detection because radar sensors have the two primary advantages: all-weather and day or night imaging. However, atmospheric effects on SAR imaging can not be bypassed and any remote sensing image has various geometric distortions, In this study, radiometric and geometric calibrations for RADARSAT/SAT data are tried using SGX products georeferenced as level 1. Even comparison of the near vs. far range sections of the same images requires such calibration Radiometric calibration is performed by compensating for effects of local illuminated area and incidence angle on the local backscatter, Conversion method of the pixel DNs to beta nought and sigma nought is also investigated. Finally, automatic geometric calibration based on the 4 pixels from the header file is compared to a marine chart. The errors for latitude and longitude directions are 300m and 260m, respectively. It can be concluded that the error extent is acceptable for an application to open sea and can be calibrated using a ground control point.

• Journal of Korean Society for Geospatial Information Science
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• v.8 no.1 s.15
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• pp.85-95
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• 2000

There is a recent emphasis on the need for updating and revision of existing digital maps as more digital maps are used and produced. Various type of data sources, such as photographs, ground surveyed data and satellite images, are used in the revision and the updating process. The process is very time consuming and costly, especially for small regional areas. This study, attempts to present an effective update/revision method using the as-built surveying drawings and the accuracy of the digital map which has been updated and revised using this method was also investigated. This study showed that by using as-built surveying drawings of scale 1/1,200 to update a digital map of scale 1/1,000, the resulting accuracy satisfied the requirements of the national digital map accuracy specification for the corresponding scale. The necessity of the existence of the necessary drawings and maps is a requirement of this process and it is also suggested that densification of local control points especially in the urban areas is necessary for producing accurate as-built surveying drawings. This would require the establishment of rules and regulations which would require constructions to perform as-built surveying, immediately after the construction has been completed.

• Journal of Korean Society for Geospatial Information Science
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• v.11 no.1 s.24
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• pp.61-69
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• 2003

The study is the open area keeping a few visible satellites and the urban area covered with the high building, an electric pole were chosen for evaluation of accuracy of satellite positioning. First, suggest the validity of RTK-GPS, RTK-GPS/GLONASS and compared the accuracy with that of the classical surveying method. As a result. In urban area, in case of real time kinematic positioning when compare between the method combined by GPS/GLONASS and by GPS alone the result of GPS/GLONASS - combination more excellent. And in open ana positioning combined GPS/GLONASS was more excellent than GPS alone in both real time differential and real time kinematic. So, RTK-GPS, RTK-GPS/GLONASS contribute to the digital mapping of Basic map and the existed map necessary for the building of PBLIS to the computerization of cadastral map in the effectiveness in time and in cost and hereafter the combined GPS/TS is expected to contribute to the development of NGIS, Re-investigation of a land register, the execution drawing on site.

• The Journal of Korea Robotics Society
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• v.7 no.3
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• pp.205-215
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• 2012

A GPS sensor is widely used in many areas such as navigation, or air traffic control. Particularly, the car navigation system is equipped with GPS sensor for locational information. However, when a car goes through a tunnel, forest, or built-up area, GPS receiver cannot get the enough number of satellite signals. In these situations, a GPS receiver does not reliably work. A GPS error can be formulated by sum of bias error and sensor noise. The bias error is generated by the geometric arrangement of satellites and sensor noise error is generated by the corrupted signal noise of receiver. To enhance GPS sensor accuracy, these two kinds of errors have to be removed. In this research, we make the road database which includes Road Database File (RDF). RDF includes road information such as road connection, road condition, coordinates of roads, lanes, and stop lines. Among the information, we use the stop line coordinates as a feature point to correct the GPS bias error. If the relative distance and angle of a stop line from a car are detected and the detected stop line can be associated with one of the stop lines in the database, we can measure the bias error and correct the car's location. To remove the other GPS error, sensor noise, the Kalman filter algorithm is used. Additionally, using the RDF, we can get the information of the road where the car belongs. It can be used to help the GPS correction algorithm or to give useful information to users.

• The Journal of Information Systems
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• v.8 no.1
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• pp.149-176
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• 1999

Regional information infrastructure(RII) plays an increasingly important role in determining the competitiveness of companies operating within the region. The purposes of this research are (1) to identify the types of RII demanded by the companies operating within Pusan and KyungNam areas in Republic of Korea, (2) to explain the levels of RII demand using variables including organizational environment, organizational strategy, and the importance of information systems for the organization, and (3) to examine whether the types of RII demand are different depending on the competition strategies that companies are pursuing. The most important type of RII that region companies demand is information systems personnel having knowledge in systems control, systems planning, communication network, database administration, and system construction. In addition, demanded are TSDN, satellite communication network, and shareable software and hardware. The levels of RII demand are different depending on the importance of information systems(IS) roles for the businesses. The more important IS role is for a company, the more sharable computing equipments and facilities are demanded. The importance of IS role is affected by the organizational environment and organizational strategy. The levels of RII demand are different also depending on the competitive advantages that companies are pursuing. Companies focusing on achieving short-term and direct benefits using information technology tend to have higher demands on sharable computing equipments and facilities as well as on information communication services. This research is explorative in nature One major limitation of this research, therefore, is that the plausibility of the postulated hypotheses was not examined simultaneously. This research is meaningful in that it first attempted to measure the demands of regional companies for RII.

• Aerospace Engineering and Technology
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• v.1 no.2
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• pp.132-140
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• 2002

By utilizing OSMI (Ocean Scanning Multi-spectral Imager) onboard KOMPSAT-1, the moon can be imaged. Because the moon has no atmosphere and reflects sun lights at a constant rate, it can be the radiance source for calibration of OSMI. But there are a lot of risks which made KOMPSAT-1 enter into safe-hold mode. So planning the imaging of the moon with OSMI should be determined seriously with consideration to information on KOMPSAT-1 operation, the moon, the sun, etc. But it takes a long time for determining the imaging time of the moon using MCE(Mission Control Element) simulator and there are operational problems to be solved. In this paper, fast simulator for determining imaging time for the moon with OSMI has been developed. The proper timeline for imaging the moon and the position of the moon image in OSMI image coordinates and the phase of the moon are determined. STK was used for acquiring information on KOMPSAT-1, the moon, the sun and the characteristitcs of OSMI are considered. As a result, we can determine imaging time of the moon with OSMI much faster and efficiently.

• The Korean Journal of Air & Space Law and Policy
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• v.3
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• pp.233-258
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• 1991

This paper examines current developing status of space law as defined in terms of its unique principle that "the utilization of outer space for all mankind's interest". As commercialization of space activities has brought about heated debate on its legitimacy with respect to that principle, space law has come to witness a dual situation. One is the realization of that principle in establishing commercial space activities system where all mankind's interest is respected through the non-discriminatory distribution mode of space benefit. In satellite telecommunication system, the INTELSAT Organization assures its public service policy while protecting itself against a competition from separate systems. For remote sensing, commercialization of LANDSAT Systems promoted since 1984 seems not to affect present non-discriminatory distribution of data and information obtained. On the other hand, active participation of private entity aiming at commercial profit enables national government to manage more effective control and supervision of those activities with a view to promoting national interests. Also, newly developed private rules and regulations are emerging in business relations about commercial space activities. Extended capacity of national government assuring its national interest in production and distribution of international resources that is outer space, and regulation of space activities by newly developed rules and customs provoke a concern about a identity problem of space law. The best way to summarize this perspective might consist in saying that non space law regulations, which are not assumed as aiming at the promotion of all mankind's interest, are confirming their role about space related activities. For those reasous, we are now facing a developing status of space law as developments of commercial space activities continues.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.5
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• pp.906-912
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• 2012

A ship ad-hoc network (SANET) can provide ships with diverse multimedia services by replacing expensive satellite communications. While ITU-R M. 1842-1, standards for maritime VHF band digital communications, can be used as the specifications of physical layer for SANETs, no standards are specified for higher layers of SANETs. In this paper, we propose a ship ad-hoc communication (SAC) protocol for SANETs, based on medium access control (MAC) and routing protocols for terrestrial ad-hoc networks. SAC protocol is a cross-layer protocol which combines MAC and routing into one algorithm and considers maritime environments, including the existence of neighboring ships, the possibility of routing to a destination, and changing the communication mode in case of VHF channel failure.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.1
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• pp.113-119
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• 2003

During the mission operation time, it is very important to estimate the spacecraft propellant remaining as accurately as possible. This is because the quantity of propellant is related directly to how long the satellite can be operated ín orbit. There are two different methods for spacecraft propellant gauging; the PVT method and the book-keeping method. This paper describes the characteristics and applications of these methods using the flight operation data of KOMPSAT-1. Additionally, propellant consumption rates in delta-V maneuvering and each attitude control submode are analyzed according to spacecraft operation modes. The earth search submode shows the highest propellant consumption rate.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.06a
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• pp.19-20
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• 2009

International Maritime Organization(IMO) recommends the installation of an Automatic Identification System(AIS) according to requirements by SOLAS Chapter 5 to avoid maritime collision. AIS provides traffic information of other ships that may be used for maritime traffic control, SAR(Search and Rescue) and collision avoidance to apply safety management. In this paper, preliminary results to implement an aeronautical surveillance transceiver using AIS transceiver based on ADS-B concepts are described. Although altitude information is not required for AIS since the AIS is operated at MSL(Mean Sea Level), altitude information can be extracted by a GPS chip-set in the ALS transceiver. ADS-B transceiver is implemented by defining a surveillance message format including the altitude information and modifying SOTDMA protocol. Ground tests and flight tests are performed to validate the implementation results.