• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1771-1774
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• 2005

Recently, RFID has become popular in the field of remote sensing applications. Location awareness is one of the most important keys to deploying RFID for advanced object tracking. Generally, multiple reference RF stations or additional sensors are used for the location sensing with RFID, but, particularly in indoor environments, spatial layout and cost problems limit the applicability of those approaches. In this paper, we propose a novel method for location sensing with active RFID systems not requiring the need for reference stations or additional sensors. The system triangulates the position of RF signal source using the signal pattern of the loop antenna connected to the power detector. The power detector consists of a signal strength detector and a signal analysis unit. The signal analysis unit indicates the signal strength and serial number using the signal from the strength detector, and provides the direction of the signal to the application target. We designed three different signal analysis units depending on the threshold type. The developed system can sense the direction to the transponder located over 10 m away within the maximum error of $5^{\circ}$. It falls within a reasonable range in our normal office environment.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.10
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• pp.13-19
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• 2007

Location awareness is one of the key functions to build U-city. Recently, many of works for location-aware systems are emerging to commercially apply to on-going large-scale apartment complex. As dwellers or cars being attached with active tags are moving in the U-city complex, the active tags periodically broadcast their own identifiers mu routers fixed along the street or in a building use those information to calculate location of thorn. There are several issues to be considered for such an environment. In this paper we propose i) a new architecture for location-aware system considering such issues ii) technical issues to implement it using active tags, and iii) a mathematical analytic model to investigate overall performance and verify it by comparing with actual experimental results. Through mathematical analysis, we can show that it is more efficient for the routers to send location signals than the tags do. We also show that there are several additional services available in the apartment complex. We conduscted several experiments hi a real ease parking lot to show that our system can locate the location of dwellers or cars.

• Journal of Digital Convergence
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• v.17 no.9
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• pp.375-381
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• 2019

Recently, the recommendation system has attracted the attention of users as customized recommendation services have been provided focusing on fashion, video and music. But these services are difficult to provide users with proper service according to many different contexts because they do not use contextual information emerging in real time. When applied contextual information expands dimensions, it also increases data sparsity and makes it impossible to recommend proper music for users. Trying to solve these problems, our study proposed a music recommendation system to recommend proper music in real time by applying association rules and using relationships and rules about the current location and time information of users. The accuracy of the recommendation system was measured according to location and time information through 5-fold cross validation. As a result, it was found that the accuracy of the recommendation system was improved as contextual information accumulated.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.270-271
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• 2015

Recently, There is Increasing interest in the intelligent services using the Internet of Things indoor positioning technologies that enable the communication of information between the objects. In particular Applications and demand for the indoor location based services using smart devices has made active. An indoor location positioning technology for this purpose BLE (Bluetooth Low Energy) has been a lot of interest in technology increases. If iBeacon of BLE(Bluetooth Low Energy) is made available to provide a signal for the indoor location information measurement then reliability of Indoor location information is lowered by signal interference. In this paper, Proposes a technique for data acquisition method for obtaining reliable position information and reliable position information calculation method from signal information data of iBeacon.

• Journal of Korea Multimedia Society
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• v.12 no.1
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• pp.156-167
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• 2009

Computing environment is evolving rapidly to ubiquitous environment. It thus makes people access and utilize any resource on the move and makes location of objects rise to the rank of the most important information. However provision of location information is too restrictive in small environments such as a home or building. In this paper we propose a home entertainment system which supports user mobility based on sensor networks and distributed devices. The proposed system estimates a user location by using signal strength received from Bluetooth ad-hoc networks. This estimated location information can tell which device a user can take advantage of while moving. In order to prove possibility of user mobility support, the system is implemented on our UPnP A/V framework home entertainment system to provide content streaming and the result shows that a provision of service for mobile users could be possible in small ubiquitous computing environments.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.4
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• pp.111-120
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• 2009

In this paper, we propose ubiWarehouse system which can efficiently manages mass and many kinds of parts such as automotive parts. First, user's work situation is defined systematically as context type of 5W1H, context-aware system is separated on function, and each module operates independently. An efficient route is selected and relevant parts frequently treated at the same time are gathered by calculating the suitability of parts and racks. If other users currently are on a visit or are supposed to visit soon, the hun of visit is changed making a concession for preventing collision. As a result, the proposed system with avoiding competition can provide users with routes for inbound or outbound parts, and can effectively use spaces of a warehouse by arranging racks to gather relevant parts to near location. Also, individual service can be offered by evaluating user propensity using history of the warehouse job, and the accuracy of stock information can be improved by processing of unexpected context and real-time renewing of warehousing and delivering.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.10 s.89
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• pp.1011-1017
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• 2004

Ultra Wideband(UWB) technologies have been developed to exploit a new spectrum resource in substances and to realize ultra-high-speed communication, high precision geolocation, and other applications. The energy of UWB signal is extremely spread from near DC to a few GHz. This means that the interference between conventional narrowband systems and UWB systems is inevitable. However, the interference effects had not previously been studied from UWB wireless systems to conventional mobile wireless systems sharing the frequency bands such as Korean Cellular CDMA and WCDMA. This paper experimentally evaluates the interference from two kinds of UWB sources, namely a direct-sequence spread-spectrum CDMA(DS-CDMA) UWB source and an impulse radio UWB source, to a Cellular CDMA and WCDMA digital transmission system. The average frame error rate degradation of each system are presented. From these experimental results, the interference effects of DS-CDMA UWB source is not severe compared to the Impulse UWB.

• Journal of Korea Multimedia Society
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• v.15 no.5
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• pp.677-691
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• 2012

Location Based Services using GPS receiver with network enabled smart phone provides various services and many business models. Currently, many context awareness models on smart phone applications are under developing. But most of the services are based on current user position and Point of Interest(POI)s, which are very static. In this paper, we proposed and implemented multimedia tourist guide system using smart phone, which are very dynamic and provides tour guide's voice and audio service on the spot. Also we provides tour experience sharing method which can easily share the videos and pictures for each users.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.278-279
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• 2015

Recently, With the development of smart devices of interest in the intelligent indoor positioning service with a smart terminal it is increasing. The BLE(Bluetooth Low Energy) is an indoor location positioning technology has attracted the attention. However, there is no way to check the reliability of the position information collected by the smart terminal receiving a big location data. This is because the reliability of an indoor position information because of a signal interference to drop. In this paper, we propose a method of managing big data collected in order to obtain reliable position information from the position information of iBeacon.

• Journal of Information Processing Systems
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• v.8 no.3
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• pp.437-444
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• 2012

In this paper, we propose a method for predicting a user's location based on their past movement patterns. There is no restriction on the length of past movement patterns when using this method to predict the current location. For this purpose, a modified search tree has been devised. The search tree is constructed in an effective manner while it additionally learns the movement patterns of a user one by one. In fact, the time complexity of the learning process for a movement pattern is linear. In this process, the search tree expands to take into consideration more details about the movement patterns when a pattern that conflicts with an existing trained pattern is found. In this manner, the search tree is trained to make an exact matching, as needed, for location prediction. In the experiments, the results showed that this method is highly accurate in comparison with more complex and sophisticated methods. Also, the accuracy deviation of users of this method is significantly lower than for any other methods. This means that this method is highly stable for the variations of behavioral patterns as compared to any other method. Finally, 1.47 locations were considered on average for making a prediction with this method. This shows that the prediction process is very efficient.