Browsing by Author "Su, Ing-Jiunn"

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A Framework of Mining Semantic Regions from Trajectories
(2011)
Lu, Chun-Ta
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Lei, Po-Ruey
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Peng, Wen-Chih
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Su, Ing-Jiunn
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交大名義發表
With the pervasive use of mobile devices with location sensing and positioning functions, such as Wi-Fi and GPS, people now are able to acquire present locations and collect their movement. As the availability of trajectory data prospers, mining activities hidden in raw trajectories becomes a hot research problem. Given a set of trajectories, prior works either explore density-based approaches to extract regions with high density of GPS data points or utilize time thresholds to identify users' stay points. However, users may have different activities along with trajectories. Prior works only can extract one kind of activity by specifying thresholds, such as spatial density or temporal time threshold. In this paper, we explore both spatial and temporal relationships among data points of trajectories to extract semantic regions that refer to regions in where users are likely to have some kinds of activities. In order to extract semantic regions, we propose a sequential clustering approach to discover clusters as the semantic regions from individual trajectory according to the spatial-temporal density. Based on semantic region discovery, we develop a shared nearest neighbor (SNN) based clustering algorithm to discover the frequent semantic region where the moving object often stay, which consists of a group of similar semantic regions from multiple trajectories. Experimental results demonstrate that our techniques are more accurate than existing clustering schemes.
AN X-BAND EIGHT-SUBARRAY SMART ANTENNA SYSTEM FOR DIRECTION OF ARRIVAL ESTIMATION
(2014-11-01)
Tseng, Yau-Hwa
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Su, Ing-Jiunn
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Hwang, Ruey-Bing
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交大名義發表
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電機資訊學士班
An X-Band eight-subarray smart antenna system has been developed in this article to demonstrate its capability of direction of arrival estimation for correlated arriving signals. The antenna array is composed of an eight-subarray antenna and eight-track of transceiver for quadrature baseband to RF up/down conversion. Multiple classification of signal (MUSIC) and modified MUSIC algorithm with spatial smoothing are used for high resolution angle of arrival (AoA) estimation. Measured results showed that the modified MUSIC algorithm with spatial smoothing is capable of estimating target AoA with average angle error of 1.14 degrees when target arriving angles are varying from -30 degrees to 30 degrees. Accurate results of AoA estimation by simulation and measurement for stationary or dynamic targets has also been demonstrated to validate the feasibility of the proposed X-Band smart antenna system. (C) 2014 Wiley Periodicals, Inc.
Dummy-Based Schemes for Protecting Movement Trajectories
(2012-03-01)
Lei, Po-Ruey
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Peng, Wen-Chih
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Su, Ing-Jiunn
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Chang, Chien-Ping
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資訊工程學系
Dummy-based anonymization techniques for protecting the location privacy of mobile users have appeared in the literature. By generating dummies that move in human-like trajectories, this approach shows that the location privacy of mobile users can be preserved. However, the trajectories of mobile users can still be exposed by monitoring the long-term movement patterns of users. We argue that, once the trajectory of a user is identified, the locations of the user are exposed. Thus, it is critical to protect the movement trajectories of mobile users in order to preserve user location privacy. We propose two schemes that generate consistent movement patterns in the long run. Guided by three parameters in a user specified privacy profile, namely, short-term disclosure, long-term disclosure and distance deviation, the proposed schemes derive movement trajectories for dummies. The experimental results show that our proposed schemes are more effective than existing works in protecting movement trajectories.