• Journal of Institute of Control, Robotics and Systems
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• v.16 no.5
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• pp.433-439
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• 2010

This paper proposes a beacon color code scheduling algorithm for the localization of multiple robots in a multi-block workspace. With the developments of intelligent robotics and ubiquitous technology, service robots are applicable for the wide area such as airports and train stations where multiple indoor GPS systems are required for the localization of the mobile robots. Indoor localization schemes using ultrasonic sensors have been widely studied due to its cheap price and high accuracy. However, ultrasonic sensors have some shortages of short transmission range and interferences with other ultrasonic signals. In order to use multiple robots in wide workspace concurrently, it is necessary to resolve the interference problem among the multiple robots in the localization process. This paper proposes an indoor localization system for concurrent multiple robots localization in a wide service area which is divided into multi-block for the reliable sensor operation. The beacon color code scheduling algorithm is developed to avoid the signal interferences and to achieve efficient localization with high accuracy and short sampling time. The performance of the proposed localization system is verified through the simulations and the real experiments.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.12
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• pp.44-53
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• 2007

In this paper, we focus on the developments of complex location awareness algorithms for real-time location based service and precise/stable localization in the outdoor. In the case of using galileo satellite system along with GPS, several error factor such as the ionosphere can be reduced for an increment of used frequency and visible satellites. Therefore, localization estimation error is no longer having problems with location awareness. But, chips synchronization error induces the error of acquisition and tracking, and the performance of receiver can be decreased. In order to solve this problem, this paper proposes a correlator for performance improvement of receiver in the precise localization.

• International Journal of Internet, Broadcasting and Communication
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• v.10 no.3
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• pp.42-50
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• 2018

The majority of existing falling recognition techniques provide service by recognizing only that the falling occurred. However, it is important to recognize not only the occurrence of falling but also the situation before and after the falling, as well as the location of the falling. In this paper, we design and propose the falling notification service system to recognize and provide service. This system uses the acceleration sensor of the smartphone to recognize the occurrence of a falling and the situation before and after the falling. In order to check the location of falling, GPS sensor data is used in the Google Map API to map to the map. Also, a crosswalk map converted into grid-based coordinates based on the longitude and latitude of the crosswalk is stored, and the locations before and after falling are mapped. In order to reduce the connection speed and server overload for real-time data processing, fog computing and cloud computing are designed to be distributed processing.

• Korean Journal of Geomatics
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• v.4 no.2
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• pp.59-65
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• 2004

Recently, a lot of interest focuses on DGPS with which it is possible to obtain 3D geographic information in real time. There are some methods to transmit corrected signals which use ground based systems as beacon, as well as wireless and TV broadcasting media. However, these methods require a large number of stations. Therefore, when the distance from station to user is increased, there is a range limit to the transmission of corrected signals. In order to solve these problems, WADGPS method using Geo-satellite is being investigated. In this study, static and kinematic tests were performed by using Satloc SLX WADGPS and Ashtech receivers. The results showed that SA was affected most among corrected signals of WADGPS; it was followed by ionospheric delay, tropospheric delay and satellite orbit errors. The accuracy of static observation was approx. $\pm$1m on SA-on. This was ten times as accurate as that of absolute observation by common receiver on SA-off. In the SA-off, the accuracy of WADGPS can be improved further. The result of kinematic tests by WADGPS acted in concert with that of standard DGPS by C/A code. It was concluded that the application of W ADGPS could improve considerably navigation and the construction of geographic information.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.598-601
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• 2006

The radio signal in GNSS was intentionally designed with two frequencies in order to combat the dispersion error caused by trans-ionospheric propagation. By measuring the path delay independently at the two, widely spaced GPS frequencies, L1 & L2, the TEC along the path from satellite to receiver can be measured directly. The issue with dual frequency measurement of the ionosphere is the calibration of L1/L2 interfrequency biases. L1/L2 interfrequency biases are generated because physical electric signal paths of L1 and L2 circuits are different from each other for both satellites and receiver. Conventionally L1/L2 interfrequency bias is estimated and broadcasted by 2D ionospheric model. In this paper, we estimated IFB (interfrequency bias) by 2D & 3D ionospheric models including real time filter methods and compared the result of those and concluded the merit of 3D tomography model to recover the problem of 2D thin shell model. We confirmed our conclusion by experimental data.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.1
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• pp.10-17
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• 1996

A real time simple DGPS (SDGPS) for coastal survey is developed and in situ tested. While the accuracy of the system is almost the same as that of existing commercially available DGPS, it is very economical compared to the commercial ones. The RMS error of the positions fired by the system is estimated to be less than 2 m within the range of 30 km from the reference station. Even if the coordinates of the reference station are uncertain, they can be fixed, from the continuous GPS observation of one day, with the maximum error less than 1 m. The system is believed to be helpfully utilized to most of coastal surveys despite of some minor defects.

• Journal of the Korean Institute of Gas
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• v.6 no.1 s.17
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• pp.52-58
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• 2002

The PIG(Pipeline Inspection Gauge) is inserted in the pipeline and stores data of pipeline. In order to investigate the status of pipeline, a lot of sensors such as caliper, pressure, IMU and odometer are used. In this paper, the navigation storage data system for PIG is developed. It has master/slave structure for a real time operation. The master system stores data, while the slave system acquire the data from sensors. The performance of the developed system is verified by pull rig test.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.331-336
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• 2002

Satellite positioning technology has been widely used in all kinds of military and civil land, marine, space and aeronautical target positioning tasks, navigation activities and accurate surveying measurements since 90s in the last century due to it advantage in providing all-weather, real-time, three dimensional and high precision positioning information, as well as speed and accurate timing information. By now, it has already formed a new hi-tech industry basically. This paper briefly reviews the development of the global satellite positioning and navigation technologies including the basic information of China′s "Plough navigation system", introduces the history of satellite positioning technology and its major application fields as well as the status quo of this being industrialized trade in China, gives an account of the writers′ vision for the application and prospect of the satellite positioning technologies in China, and approaches the tactics and stresses of the satellite positioning technology′s application and its industrialization future in China.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.423-427
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• 2002

Contrary to the traditional text-based information, 4S(GIS,GNSS,SIIS,ITS) information can contribute to the citizen's welfare in upcoming era. Recently, GSIS(Geo-Spatial Information System) has been applied and stressed out in various fields. As analyzed the data from GSIS arena, the position information of objects and targets is crucial and critical. Therefore, several methods of getting and knowing position are proposed and developed. From this perspective, Position collection and processing are the heart of 4S technology. We develop 4S-Van that enables real-time acquisition of position and attribute information and accurate image data in remote site. In this study, the configuration of 4S-Van equipped with GPS, INS, CCD and eye-safe laser scanner is shown and the merits of DGPS/INS integration approach for geo-referencing is briefly discussed. The algorithm of DGPS/INS integration fur determination of six parameters of motion is eccential in the 4S-Van to avoid or simplify the complicated computation such as photogrammetric triangulation. 4S-Van has the application of Laser-Mobile Mapping System for three-dimensional data acquisition that merges the texture information from CCD camera. The technique is also applied in the fields of virtual reality, car navigation, computer games, planning and management, city transportation, mobile communication, etc.

• Journal of Radiation Industry
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• v.6 no.1
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• pp.41-47
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• 2012

A field tracer experiment using a radioisotope was conducted to analyze the transport and dispersion characteristics of pollutants in the coastal area near a Wolsung. A rod float including GPS was released to track the paths of radioisotope. NaI detector was installed to measure the released radioisotope from the boat, and measurements were performed with the real time. The measured tracer data by a field experiment can be used as the basic data for understanding the transport characteristics of pollutants and verifying numerical models near the offshore.