• Journal of the Korea Society for Simulation
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• v.25 no.2
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• pp.21-29
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• 2016

Indoor location system has been used Wi-Fi to get a location. After the development of BLE(Bluetooth Low Energy), the interest in the method of a indoor positioning had been move on. It has more advantages than using Wi-Fi. Easy installation, low power consumption, low signal interference and changeable setting(Advertising interval, tx power, etc.). These things can improve efficiency or accuracy in a indoor positioning system. For this reason, recent indoor positioning system uses BLE rather than Wi-Fi. Accordingly, error factors of BLE beacon based indoor positioning should be studying for high accuracy of indoor positioning. In this research, set up few experiment scenarios and keep a close watch on how technological, environmental factor is affecting positioning accuracy. When a application uses largest signal strength to get the indoor location, the mean error of experimental results was decreased compare to using received signal strength in real-time. The result was same when the application applied average and standard deviation to get the indoor location. Changing advertising interval had an effect on the mean error of indoor positioning. Short advertising interval makes the lower mean error than large advertising interval.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.9 no.3
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• pp.92-101
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• 2010

Energy efficiency and safe mobility are the two key constituents of the future automobile. The technologies that enable these features are now heavily dependent upon information and communication technology rather than traditional auto-mechanical technology. This paper presents an exploratory project 'Smart&Green Vehicle Project' at Western Michigan University which is to improve the geographical location accuracy of vehicles and to study various applications of making such location data available. Global Positioning System (GPS), Inertial Navigation System (INS), Vehicular Ad-hoc Network (VANET) technology, and data fusion among these technologies are investigated. Testing and evaluation is done on systems which will gather vehicular positioning data during GPS signal loss. Vehicles in urban settings do not acquire accurate positioning data from GPS alone; therefore there is a need for exploration into technology that can assist GPS in urban settings. The goal of this project is to improve the accuracy of positioning data during a loss of GPS signal. Controlled experiments are performed to gather data which aided in assessing the feasibility of these technologies for use in vehicular platforms.

• Environmental Analysis Health and Toxicology
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• v.28
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• pp.5.1-5.7
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• 2013

Objectives Despite increasing availability of global positioning system (GPS), no research has been conducted to analyze GPS data for exposure opportunities associated with time at indoor and outdoor microenvironments. We developed location-based and time-weighted spatial measures that incorporate indoor and outdoor time-location data collected by GPS. Methods Time-location data were drawn from 38 female subjects in California who wore a GPS device for seven days. Ambient standard deviational ellipse was determined based on outdoor locations and time duration, while indoor time weighted standard deviational ellipse (SDE) was developed to incorporate indoor and outdoor times and locations data into the ellipse measure. Results Our findings indicated that there was considerable difference in the sizes of exposure potential measures when indoor time was taken into consideration, and that they were associated with day type (weekday/weekend) and employment status. Conclusions This study provides evidence that time-location weighted measure may provide better accuracy in assessing exposure opportunities at different microenvironments. The use of GPS likely improves the geographical details and accuracy of time-location data, and further development of such location-time weighted spatial measure is encouraged.

• Journal of Positioning, Navigation, and Timing
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• v.12 no.2
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• pp.211-211
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• 2023

• Journal of Positioning, Navigation, and Timing
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• v.9 no.4
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• pp.379-385
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• 2020

The satellite employs an adaptive beamformer to efficiently detect various signals and to suppress multiple interference signals, simultaneously. Although the adaptive beamforming satellite system needs Angle-of-Arrival (AOA) information of the desired signal, it is difficult to estimate the signal AOAs on the satellite environment. However, the AOA estimation on the ground control tower is more efficient and accurate comparing to the satellite environment. In this paper, we propose an adaptive beamforming satellite system based on the signal location information on the ground, consisting on an angle estimator, an adaptive beamformer, and signal processing & D/B unit. The ground control tower estimates the accurate location of the signal source, and it sends the estimated coordinates of the desired signal to the satellite. The angle estimator mounted on the satellite calculates the desired signal AOA, based on the signal location information transmitted from the ground control center. The satellite beamformer detects the desired signal and suppresses unwanted signals based on the signal AOA calculated by the angle estimator. We provide computer simulation results to present the performance of the proposed satellite adaptive beamforming system based on the signal location information.

• Journal of the Korea Society of Computer and Information
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• v.17 no.6
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• pp.173-182
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• 2012

A recent advance in smart phones is increasing utilization of location information. Existing positioning system was using GPS location for positioning. However, the GPS cannot be used indoors, if GPS location has an incorrectly problem. In order to solve indoor positioning problems of indoor location-based positioning techniques have been investigated. There are a variety of techniques based on indoor positioning techniques like as RFID, UWB, WLAN, etc. But WLAN location positioning techniques take advantage the bond in real life. WLAN indoor positioning techniques have a two kind of method that is centroid and fingerprint method. Among them, the fingerprint technique is commonly used because of the high accuracy. In order to use fingerprinting techniques make a WLAN signal map building that is need to lot of resource. In this paper, we try to solve this problem in an Indoor environment for WLAN-based fingerprint of a virtual building technique, which is proposed. Proposed technique is classified Cell environment in existed Indoor environment, all of fingerprint points are shown virtual grid map in each Cell. Its method can make fingerprint grid map very quickly using estimate virtual signal value. Also built signal value can take different value depending of the real estimate value. To solve this problem using a calibration technique for the Splite-tree is proposed. Through calibration technique that improves the accuracy for short period of time. It also is improved overall accuracy using predicted value of around position in cell.

• Journal of Advanced Navigation Technology
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• v.12 no.1
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• pp.15-21
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• 2008

In this paper, person monitoring and personal identification information management by using the location positioning device and the location management system based on GPS is analysed and developed. Mobile HTE(Mobile HTE : Mobile Home Terminal Equipment) of the developed system uses the module for transmitting PID(Personal Identification Device) information and the module based on GPS's location information. HTE transmits the received information from Mobile HTE to the Location Management System through the internet system. The Location Management System is developed for person location management and information management.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.1003-1006
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• 2009

Recently, Ubiquitous computing technology is increasing necessity for object recognition and a location tracking technology to meet various applications. The location tracking technology is the fundamental to the Context-Aware of users in Ubiquitous environment and its efficiency has to be improved using IEEE 802.15.4 ZigBee used in current infra such as ubiquitous sensor network. But because the IEEE 802.15.4 ZigBee protocol has limitation to apply location tracking technology such as ToA and TDoA, Zone-based Location Tracking technology using RSSI is needed. In this paper suggests RSSI-based 802.15.4 ZigBee local positioning protocol to support a positioning tracking service in Ubiqutous environment. And Zone-based location tracking system is designed for actual the indoor location tracking service.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.9
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• pp.876-882
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• 2006

This study presents an ultrasonic location awareness system for the ubiquitous computing with absolute position. The flight time of ultrasonic waves is determined by a period detecting technique which is able to extend the sensing range compared with traditional methods. For location awareness, ultrasonic waves are sent successively from each ultrasonic transmitter and synchronized by radio frequency (RF) signal, where the transmitting part is fixed and the receiving part is movable. To expand the recognizing range, cell matching technique and coded ultrasonic technique are introduced. The experimentation for various distances is accomplished to verify the used period detecting technique of U-SAT system. The positioning accuracy by using cell matching is also verified by finding the locations of settled points and the usability of coded ultrasonic technique is verified. As a result, the possibility of ultrasonic location awareness system for the ubiquitous computing can be discussed as a pseudo-satellite system with low cost, a high update rate, and relatively high precision, in the places where CPS is not available.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.311-315
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• 2006

Precision location and positioning of Asset within a network is an attractive feature with various applications, especially in indoor environments. Such a demand is met by the standard task group, IEEE 802.15.4a. Several methods, that is, pulse, chirp and chaotic communications have been proposed so far to satisfy the requirements of the standard. Among them, ultra wideband direct chaotic communications has advantageous features such as low hardware complexity, low cost, lower power consumption and flexible frequency band plan. In this paper, the feasibility of the ranging system using non-coherent chaotic transceiver is investigated by designing and implementing the system and the performance is proved by conducting location experiments in real indoor environments.