• Journal of Engineering Education Research
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• v.15 no.5
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• pp.93-97
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• 2012

Most of ubiquitous computing devices such as stereo camera, ultrasonic sensor based MIT cricket system and other wireless sensor network devices are widely applied to the 2 Dimensional(2D) localization system in today. Because stereo camera cannot estimate the optimal location between moving node and beacon node in Wireless Personal Area Network(WPAN) under Non Line Of Sight(NLOS) environment, it is a great weakness point to the design of the 2D localization system in indoor environment. But the conventional 2D triangulation scheme that is adapted to the MIT cricket system cannot estimate the 3 Dimensional(3D) coordinate values for estimation of the optimal location of the moving node generally. Therefore, the 3D triangulation scheme based on the space segmentation in WPAN is suggested in this paper. The measuring data in the suggested scheme by computer simulation is compared with that of the geographic measuring data in the AutoCAD software system. The average error of coordinates values(x,y,z) of the moving node is calculated to 0.008m by the suggested scheme. From the results, it can be seen that the location correctness of the suggested scheme is very excellent for using the localization system in WPAN.

• Journal of the Institute of Convergence Signal Processing
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• v.12 no.3
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• pp.157-162
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• 2011

This study is about implementing wireless transferring system in pre-hospital cardiopulmonary resuscitation(CPR). Also, this study includes monitoring based feedback between patient and hospital to increase the survival rate of emergency patient by developing the performance of cardiopulmonary resuscitation in pre-hospital. It minimizes the loss of flow rate or gastric inflation through the space between the airway and the esophagus, which enables the inspiration-expiration rate to be measured more precisely. Due to these reasons this study applied ET insertion based respiratory sensor to measure flow rate. The main indices of artificial ventilation are justified from minute respiration(V), end-tidal $CO_2(E_TCO_2)$, and tracheal pressure($P_{tr}$). The simulation is performed to verify the bandwidth and delay time of transport network for in-hospital monitoring even as transporting images and voice information simultaneously. The total bandwidth is 815 kbps, and WLAN (IEEE 802.11x) is used as communication protocol. The network load is under 1.5% and the transmit delay time is measured under 0.3 seconds.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.107-112
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• 2015

A smart phone and the number of wireless terminals are mobile-to the nature of the AP mobility are many call transfer between wireless terminals and AP (Access Point). Each wireless terminal that is the call processing process for each is relatively large to cause the wireless traffic, and a factor that inhibits the efficient use of the radio band on the AP. In this paper, we use the power intensity threshold and threshold timer of the AP received by the mobile station to reduce the amount of switching traffic between the AP's cause and traffic generation factors between the wireless device and the AP that can effectively utilize the radio traffic from the AP the measures proposed. The proposed method and the conventional method is improved by simulation to handle the amount of radio traffic from the AP it was confirmed that it is possible to effectively utilize the whole of the radio band.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.2
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• pp.165-171
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• 2013

WAVE(Wireless Access in Vehicular Environments) is a representative V2V communication protocol and its standards of MAC and PHY parts except for security were published. In order to control traffic flow and ensure driver's safety using V2V communication, various projects are conducting. In particular, safety application has been researched. Therefore, in this paper, we designed the safety application algorithm, which informs a driver of the dangerous status when driver tries to turn left in an intersection and we also implemented the algorithm. Proposed algorithm configures a model for a host vehicle and a vehicle coming in opposite lane and in case that there is collision hazard it provides warning message to driver by using HMI. In order to evaluate the proposed algorithm's performance, we configured the test bed using test vehicles and we tested the algorithm on proving ground with the composed test scenarios. As test results, our system showed excellent performance. If the infrastructures for V2I communications are constructed, we will optimize our system more precisely and stably.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.83-88
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• 2006

Many applications in the area of location-based services and personal navigation require nowadays the location determination of a user not only in outdoor environment but also indoor. To locate a person or object in a building, systems that use either infrared, ultrasonic or radio signals, and visible light for optical tracking have been developed. The use of WiFi for location determination has the advantage that no transmitters or receivers have to be installed in the building like in the case of infrared and ultrasonic based location systems. WiFi positioning technology adopts IEEE802.11x standard, by observing the radio signals from access points installed inside a building. These access points can be found nowadays in our daily environment, e.g. in many office buildings, public spaces and in urban areas. The principle of operation of location determination using WiFi signals is based on the measurement of the signal strengths to the surrounding available access points at a mobile terminal (e.g. PDA, notebook PC). An estimate of the location of the terminal is then obtained on the basis of these measurements and a signal propagation model inside the building. The signal propagation model can be obtained using simulations or with prior calibration measurements at known locations in an offline phase. The most common location determination approach is based on signal propagation patterns, namely WiFi fingerprinting. In this paper the underlying technology is briefly reviewed followed by an investigation of two WiFi positioning systems. Testing of the system is performed in two localization test beds, one at the Vienna University of Technology and the second at the Hong Kong Polytechnic University. First test showed that the trajectory of a moving user could be obtained with a standard deviation of about ${\pm}$ 3 m.