Hae-Young Bae

Efficient spatial data transmission in Web-based GIS

This paper has proposed a new method of efficient spatial data transmission in the client-side Web-Based GIS (Geographic Information System) which handles large-size spatial geographic information on the Internet. The basic idea is that, firstly, a largesize map is divided into several parts, where each part is called a “Tile”, according to appropriate division granularity. Secondly, when an user requires a certain region in the map at client side, the GIS server only transmits spatial data in the tiles which overlap with the requested region. And the received data are stored in client local machine for reuse. Here a method of tile-division and tile-query processing has been provided. Comparing with traditional client-side Web-Based GIS, the performance improvement is achieved by the usage of the proposed method.

FDSI-Tree: a fully distributed spatial index tree for efficient & power-aware range queries in sensor networks

In this paper, a fully distributed spatial index tree (FDSI-tree) is proposed for efficient & power-aware range queries in sensor networks. The proposed technique is a new approach for range queries that uses spatial indexing. Range queries are most often encountered under sensor networks for computing aggregation values. However, previous works just addressed the importance but didn’t provide any efficient technique for processing range queries. A FDSI-tree is thus designed for efficiently processing them. Each node in the sensor network has the MBR of the region where its children nodes and the node itself are located. The range query is evaluated over the region which intersects the geographic location of sensors. It ensures the maximum power savings by avoiding the communication of nodes not participating over the evaluation of the query.

A Full-Reference Image Quality Assessment Algorithm Based on Haar Wavelet Transform

This paper proposes a new objective full-reference (FR) image quality assessment method with discrete Haar wavelet transform (HWSSIM). Here, both reference and test images are decomposed into four bands by 2-D Haar wavelet transform: LL, HL, LH and HH. The luminance and contrast information are extracted in the LL band, and the edge structure information is obtained with edge information map based on other three bands and the whole image quality is defined as MHWSSIM. We also develop our algorithm on the multi-resolutions case (MRHWSSIM). which is defined as the human visual system (HVS) contrast sensitivity based weighted mean of four MHWSSIM values evaluated at four Haar wavelet decomposition levels. Experiment results indicate that the proposed methods are better correlated with HVS when compared to PSNR, MSSIM and MGSSIM.

Hybrid index for spatio-temporal OLAP operations

According to increase of spatial data, many decision support systems require the fast spatio-temporal analysis. This paper proposes the improved index for efficient OLAP in a spatial data warehouse. The main idea is to use the hybrid index of the extended aggregation R-tree and the sorted hash table. The extended R-tree supports the spatial hierarchy with the level of R-tree. Also, it provides pre-aggregation for fast retrieval of the aggregated value. The sorted hash table is the transformed hash table for supporting the temporal hierarchy. So, it provides pre-aggregation of each temporal unit, year, month and etc. By the proposed hybrid index, an efficient spatio-temporal analysis can be sup-ported since it provides the spatio-temporal hierarchy and the pre-aggregated value.

Extension of Geography Markup Language (GML) for Mobile and Location-Based Applications

Geography Markup Language (GML) has been extended for mobile and location-based applications. Three schemas are included in the extension, i.e., voice schema, tracking schema, and POI (Point Of Interest) schema. In order to handle effectively the extension, we also have designed a Spatial XQuery language and its processing modules. Because our work is based on a spatial database system, the Spatial XQuery statements are first translated into SQL statements. By working on an existing spatial database system, we can use of the existing amenities of database systems such as query optimization, spatial indexes, concurrency control, and crash recovery. Translation of the Spatial XQuery into SQL has been explained using examples. Because the results from the spatial database system are in the form of tables, we need to translate again the results into XML statements. A working example of the proposed system as an Emergency Support System is also presented. Prospected application areas of the proposed system are almost all mobile and location-based systems such as LBS (Location-based System), POI systems, tracking systems, ubiquitous systems, and distributed control and management systems.

Spatio-temporal Similarity Measure for Network Constrained Trajectory Data

Trajectory similarity measure is an important issue for analyzing the behavior of moving objects. In this paper, a similarity measure method for network constrained trajectories is proposed. It considers spatial and temporal features simultaneously in calculating spatio-temporal distance. The crossing points of network and semantic information of trajectory are used to extract the characteristic points for trajectory partition. Experiment results show that the storage space is decreased after trajectory partition and the similarity measure method is valid and efficient for trajectory clustering.

Adaptive Cell-Based Index For Moving Objects In Indoor

Existing R-tree that is based on a variety of outdoor-based techniques to manage moving objects have been investigated. Due to the different characteristics of the indoor and outdoor, it is difficult to management of moving object using existed methods in indoor setting. We propose a new index structure called ACII(adaptive Cell-based index for Indoor moving objects) for Indoor moving objects. ACII is Cell-based access structure adopting an overlapping technique. The ACII refines cells adaptively to handle indoor regional data, which may change its locations over time. The ACII consumed at most 30% of the space required by R-tree based methods, and achieved higher query performance compared with r-tree based methods.

A Specification of a Moving Objects Query Language over GML for Location-Based Services

We propose a specification of moving objects query language over GML for LBS extended by XQuery. Conventional query languages over GML have been focused on the development of interoperable Web GIS, the enrichment of existing XML language with spatial operators, and etc. However, these studies are not suitable for direct query of GML repositories by the lack of alignment with XQuery. Also, there is no consideration on the query language over GML to support moving objects query for LBS. Therefore, we show the data model, the algebra, the set of operators and representative query examples underlying the proposed moving objects query language to specify moving objects features. Finally, we apply the proposed query language to tornado monitoring system to show that this language comes into use in various LBS applications effectively.

An in-network data cleaning approach for wireless sensor networks

AbstractWireless Sensor Networks (WSNs) are widely used for monitoring physical happenings of the environment. However, the data gathered by the WSNs may be inaccurate and unreliable due to power exhaustion, noise and other reasons. Unnecessary data such as erroneous data and redundant data transmission causes a lot of extra energy consumption. To improve the data reliability and reduce the energy consumption, we proposed an in-network processing architecture for data cleaning, which divides the task into four stages implemented in different nodes respectively. This strategy guaranteed the cleaning algorithms were computationally lightweight in local nodes and energy-efficient due to almost no communication overhead. In addition, we presented the detection algorithms for data faults and event outliers, which were conducted by utilizing the related attributes from the local sensor node and the cooperation with its relaying neighbor. Experiment results show that our proposed approach is accurate and energy-...

Design and implementation of zero-copy data path for efficient file transmission

Huge requests for file transmission by concurrent users cause excessive memory copy operations and system calls between kernel and user space, which are very expensive and require many CPU cycles for processing. And it has been a bottleneck that limits the number of serviceable requests and prevents CPU resources from being allocated to other processes. In this paper, we suppose the zero-copy data path for efficient file transmission to solve the upper described problems. To do that, we used existing system call interface, sendfile, for file transmission from one device to another and used the same buffer page to transmit a file. The supposed zero-copy data path reduces CPU cost per transaction by eliminating CPU copies between kernel and user space and by avoiding unnecessary system calls in user space. The improved CPU efficiency means that a larger number of requests can be serviced with the same CPU configuration.