• Journal of the Korea Society of Computer and Information
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• v.10 no.2 s.34
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• pp.179-186
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• 2005

This study is to develop PDA_based surveying mapping system. This object is achieved by developing wireless communication module of PDA which is adaptable to Total Station and GPS. and contents for its usage. This system will be efficiently used to surveying parts of spatial location information for real time mapping and improving the modification of survey data.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.6
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• pp.610-618
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• 2011

For improved localization around the indoor/outdoor transit area of buildings, this paper proposes an efficient algorithm combining the measurements from the WLAN (Wireless Local Area Network) and the GPS (Global Positioning System) for. The proposed hybrid localization algorithm considers both multipath errors and NLOS (Non-Line-of-Sight) errors, which occur in most wireless localization systems. To detect and isolate multipath errors occurring in GPS measurements, the propose algorithm utilizes conventional multipath test statistics. To convert WLAN signal strength measurements to range estimates in the presence of NLOS errors, a simple and effective calibration algorithm is designed to compute conversion parameters. By selecting and combining the reliable GPS and WLAN measurements, the proposed hybrid localization algorithm provides more accurate location estimates. An experiment result demonstrates the performance of the proposed algorithm.

• Journal of electromagnetic engineering and science
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• v.17 no.4
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• pp.181-185
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• 2017

In this paper, we propose an angle-of-arrival (AoA)-based local positioning system using a time-modulated array (TMA). The proposed system can determine a two-dimensional position using only two TMAs without any synchronization between the two receivers. The hardware for the proposed system consists of two commercial monopole antennas, a self-designed switch, and a well-known software-defined radio receiver. Furthermore, the location can be simply estimated in real time without the need for complicated positioning algorithms such as the MUSIC and ESPRIT algorithms. In order to evaluate the performance of our system, we estimated the position of the wireless node in an office environment. The position was estimated with a mean error of less than 0.1 m. We therefore believe that our system is appropriate for various wireless local positioning applications.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.3
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• pp.510-515
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• 2005

Doppler spread can occur due to the relative movement of transmitter and receiver. The Doppler frequency shift varies as the relative location and the velocity of transceivers change. This Doppler spread may seriously degrade the performance of OFDM system which is considered to be very efficient for multimedia wireless communication. Therefore, applying the method of receiver diversity, we analyze the degree of BER improvement in Doppler spread environments to investigate the effectiveness of the chosen methods according to various wireless channels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1B
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• pp.39-45
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• 2006

In this paper, existing technology that uses broadcasting and multicasting IP addrsses at the wireless access network, based on Internet as a core network, is upgraded. By employing broadcasting service request by receivers, convergence of multicasting and broadcasting, and lower level filtering of broadcast data, the load and traffic of network, server, base station, and receiver is substantially reduced. The technology proposed in this paper could be useful for general broadcasting services, and especially optimum for LBS and Telematics services.

• Journal of Engineering Education Research
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• v.13 no.2
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• pp.7-11
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• 2010

As the development of the computer and communication technologies, the ubiquitous society can be realized to the world early in the future. Thus, the localization system in Wireless Personal Area Network (WPAN) is required for many users of ubiquitous society to provide the ubiquitous computing based applications in respective of anytime and anywhere. In this paper, we propose the distance measurement scheme that is based on the distance measurement using RSSI (Received Signal Strength Indicator) of sensor module considering of two distance conditions for the localization system using Zigbee in WPAN. Also, the localization errors of the proposed scheme are analyzed in the three scenarios that the mobile module tracks in the in $6m{\times}6m$ scaled experimentation area. In addition to this, the monitoring subsystem is developed using GUI (Graphical User Interface) in order to monitor the location of the moving objects accurately and user-friendly.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2004.11a
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• pp.299-304
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• 2004

With the development of mobile and wireless environments, the Ubiquitous era has com on the base of technologies of Semantic Web and Web Services. To accelerate proliferation of the E-Commerce in the Ubiquitous era, the importance of information search is emphasized more and more and its time to need more intelligent search for product and service which can consider location and other context-aware related information. As a starting point to meet these requirements, we proposed more effective product information search service framework through web services under semantic web environment. Over the wireless internet and we also examined its technical validity with the prototype system, implemented prototype and investigated the technological possibility.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.2A
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• pp.124-129
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• 2002

We propose a wireless positioning system using IC-IPDL method that exploits the modified-IPDL method and the interference cancellation techniques to improve hearability. In the proposed system, IPDL method is modified to maintain the transmission of CPICH for stability of CDMA network Simultaneously in mobile CPICH is cancelled out using the interference cancellation techniques for improving hearability. The simulation results showed that the proposed location system has a compatible performance to the standard IPDL method though CPICH exists during idle period.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.8
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• pp.742-747
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• 2004

Outdoors we can easily acquire our accurate location by GPS. However, the GPS signal can't be acquired indoors because of its weak signal power level. Adequate positioning method is demanded for many indoor positioning applications. At present, wireless local area network (WLAN) is widely installed in various areas such as airport, campus, and park. This paper proposes a positioning algorithm using WLAN signal strength to provide the position of the WLAN user indoors. There are two methods for WLAN based positioning, the signal propagation method uses signal strength model over space and the empirical method uses RF power propagation database. The proposed method uses the probability distribution of the power propagation and the maximum likelihood estimation (MLE) algorithm based on power strength DB. Test results show that the proposed method can provide reasonably accurate position information.

• Journal of Industrial Technology
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• v.27 no.B
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• pp.37-42
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• 2007

A mobile ad hoc network (MANET) is a kind of wireless ad hoc network. It is a self-configuring network of mobile nodes connected by wireless links. Infostation is a lower cost and low power system that provides very high bit rate with limited coverage. In this study, we propose search and rescue system that combines MANET of climbers with Infostations. A climber shares location information of climbers with other climbers while climbing, and delivers the information to Infostations. This system is an intermittent network due to the mobility of nodes. From the system, we can track the locations of missing climbers. Ultimately, proposed system achieves low cost and reduces memory requirement using Infestations. We also analyze the performance of the proposed system by simulation. From the performance analysis results, we expect that the proposed system will be very useful to early detect climbers' locations in emergency situations in Korea mountain areas.