• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.348-353
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• 2008

Despite the increasing popularity of wireless sensor network, indoor positioning using low power IEEE 802.15.4 compliant radio had attracted an interest of many researchers in the last decade. Old fashionable indoor location sensing information has been presented in dull and unpleasant 2D image standard. This paper focused on visualizing high precision 3 dimensional RSSI-based (received signal strength indication) spatial sensing information in an interactive virtual reality on PDA. The developed system operates by capturing and extracting signal strength information at multiple pre-defined reference nodes to provide information in the area of interest, thus updating user's location in 3D indoor virtual map. VRML (Virtual Reality Modeling Language) which specifically developed for 3D objects modeling is utilized to design 3D indoor environment.

• Journal of Information Technology Services
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• v.9 no.3
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• pp.145-161
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• 2010

Recently, identifying user locations is becoming important as the society evolves into an ubiquitous society with the innovation of information technology. Particularly, many researches on identifying user locations are headed in direction to identify locations of users in the indoors, because a GPS that is widely used to identify the locations of users in the outdoors is inapplicable in the indoors. However, those researches are mostly not useful to general indoor environment because they are performed in a specific environment with specialized or customized devices such as UWB, RFID. Therefore, in this paper we propose a effective method to identify user locations in general indoor environments with wireless local network access points. Our approach enables to identify user location efficiently by measuring signal power of access points around the user and using the FRIIS formula which is used to calculate the distance among the things.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.7
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• pp.852-860
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• 2019

In this paper, we proposed a new trilateration technique based on exponential moving average (EMA) filter with adaptive signal model which enhances accuracy of positioning system even if the RSSI changes randomly due to movement of obstacles or blind node in indoor environment. In the proposed scheme, three fixed transmitters sent out the signal to blind node. The transmitter decides the location of the blind node based on RSSI and it estimates the cause of RSSI fluctuation which is interference of obstacle or movement of blind node. When the path between blind node and transmitter has become NLOS path because of obstacles, the transmitter ignores the measured RSSI in NLOS path and replace estimated RSSI in LOS environment. In the other case, the transmitter updated the new RSSI to represent of movement of blind node. The proposed scheme has been verified on a ZigBee testbed and we proved the improved positioning accuracy compared to the existing indoor position system.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.67-70
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• 2006

For a long time the GSM and GPS world has been living side by side. There have been some half hearted attempts to invoke the GPS unit into GSM units but performance and usability has suffered. The A-GPS approach is interesting and we wanted to verify general performance for fleet application and alarm/emergency situations. The result is now promising but still more to enhancements are anticipated. We achieved near acceptable availability (${\sim}70%$) under indoor conditions. Accuracy was as anticipated (50-100 meter) as we are using reflected signals. Time to first fix is in general good in outdoor conditions but too long for indoor conditions (45-60 seconds). We would like manufactures to put some more effort to get better performance in the future as test with Nordnav high sensitivity measurement system proves that conditions indoor are at a level where better performance should be possible.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.5
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• pp.38-47
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• 2008

The most commonly used location recognition system is the GPS-based approach. However, the GPS is inefficient for an indoor or urban area where high buildings shield the satellite signals. To overcome this problem, this paper propose the indoor positioning method using wavelet and neural network. The basic idea of proposed method is estimated the location using the received signal strength from wireless APs installed in the indoor environment. Because of the received signal strength of wireless radio signal is fluctuated by the environment factors, a feature that is strength of signal noise and error and express the time and frequency domain is need. Therefore, this paper is used the wavelet coefficient as the feature. And the neural network is used for estimate the location. The experiment results indicate 94.6% an location recognition rate.

• Journal of Information Technology Applications and Management
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• v.26 no.5
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• pp.41-56
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• 2019

Recently great loss of life and property is occurring because of fire, natural disaster, earth quake, tsunami and so on. People spend 80~90% of their time indoor environment like office, supermarket, campus. Therefore Indoor navigation and guidelines system became so essential for most of all. Incase of emergency we must be careful earlier, in such a cases 5G kind of new technology may also cannot work. So immediate action and quick routing notification for guidelines and protection is the most. Considering this issue We proposed indoor evacuating guidance system based on microcontroller Wi-Fi board for Indoor APP using mobile. Focusing various kind of technology like, ok google, voice search APP we purposed node architecture based system. When we listen fire alarm while living inside the room. Then to be safe we connect with server and start Arduino UNO+IoT ESP8266 Wi-Fi shield version1-IoT module to store data in MySQL DB server. We make application to escape out from the building up-to the three exits giving information from source point to destination. Our program can send information to the users emergency location and situations. For this when the user get sound or vibration in their mobile device it indicate fire out near by. At that time we update message from Arduino to DB server for the fixed current position inside the building which give routing signal for that fire out location by changing values from 0 to 1. We have user in point 10 where user is near by. Later we detect Wi-Fi signal form Nodemcu as room of each floor and try to connect with user. Main purpose of this paper is to save life of people in short time and find out the shortest path up to nearest exits in the time of emergencies and rescue them.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.81-84
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• 2005

Various design schemes for network using wireless sensor nodes have been widely studied on the several application areas ranging from the real world information collection to environmental monitor. Currently, the schemes are focused on the design of sensor network for low power consumption, power-aware routing protocol, micro miniature operating system and sensor network middleware. The indoor localization system that identifies the location of the distributed nodes in a wireless sensor network requires features dealing with mobility, plurality and other environmental constraints of a sensor node. In this paper, we present an efficient location system to cope with mobility of multiple mobile nodes by designing a location handler that processes location information selectively depending on the nodes' density in a specific region. In order to resolve plurality of multiple mobile nodes, a routing method for the location system is also proposed to avoid the occurrence of overlapped location data.

• Journal of Korea Multimedia Society
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• v.15 no.1
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• pp.71-80
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• 2012

LBS (Location Based Service) services are very useful to our daily life and it should be available inside a building: a huge building, a shopping mall, a large scale underground shopping center, and so on where GPS (Global Positioning System) signal is not available. An LBS which is provided inside a building is called an ILBS (Indoor Location Based Service). One of the most important techniques for ILBS development is indoor positioning. Among the indoor positioning techniques, APs (access points) of WLAN based ones are most economical because WLAN is available almost everywhere. Meanwhile, the web service has been proved to be an excellent practice of software reuse. Therefore, if indoor positioning is provided in the form of web service to programmers then development of ILBS would be greatly accelerated. This paper introduces the AP based trilateration and K-NN indoor positioning and RFID based indoor positioning web services we have developed.

• International Journal of Contents
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• v.10 no.4
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• pp.69-74
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• 2014

General location aware systems are only applied to indoor and outdoor environments using more than three transmitters to estimate a fixed object location. Those kinds of systems have environmental restrictions that require an already established infrastructure. To solve this problem, an Object Location Estimation (OLE) algorithm based on PTP (Point To Point) communication has been proposed. However, the problem with this method is that deduction of performance parameters is not enough and location estimation is very difficult because of unknown restriction conditions. From experimental tests in this research, we determined that the performance parameters for restriction conditions are a maximum transmission distance of CSS communication and an optimum moving distance interval between personal locations. In this paper, a system applied OLE algorithm based on PTP communication is implemented using a CSS (Chirp Spread Spectrum) communication module. A maximum transmission distance for CSS communication and an optimum moving distance interval between personal locations are then deducted and studied to estimate a fixed object location for generalization.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.7
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• pp.898-903
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• 2020

In this paper, we propose an indoor logistic tracking system that identifies the location and inventory of the logistics in the room based on fingerprints. Through this, we constructed the actual infrastructure of the logistics center and designed and implemented the logistics management system. The proposed system collects the signal strength through the location terminal and generates the signal map to locate the goods. The location terminal is composed of a UHF RFID reader and a wireless LAN card, reads the peripheral RFID signal and the signal of the wireless AP, and transmits it to the web server. The web server processes the signal received from the location terminal and stores it in the database, and the user uses the data to produce the signal map. The proposed system combines UHF RFID with existing fingerprinting method to improve performance in the environment of querying multiple objects.