• Journal of Korea Spatial Information System Society
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• v.11 no.2
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• pp.151-161
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• 2009

In Location-Based Services (LBSs), users requesting a location-based query send their exact location to a database server and thus the location information of the users can be misused by adversaries. Therefore, a privacy protection method is required for using LBS in a safe way. In this paper, we propose a new cloaking region generation algorithm using grids for privacy protection in LBSs. The proposed algorithm creates a m inimum cloaking region by finding L buildings and then performs K-anonymity to search K users. For this, we make use of not only a grid-based index structure, but also an efficient pruning techniques. Finally, we show from a performance analysis that our cloaking region generation algorithm outperforms the existing algorithm in term of the size of cloaking region.

• Journal of KIISE:Databases
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• v.29 no.4
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• pp.321-333
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• 2002

As web-based services are becoming more and more popular, concurrent updates of spatial data should be possible in the web-based environments in order to use the various services. Web-based GIS applications are characterized by large quantity of data providing and these data should be continuously updated according to various user's requirements. Faced with such an enormous data providing system, it is inefficient for a server to do all of the works of updating spatial data requested by clients. Besides, the HTTP protocol used in the web environment is established under the assumption of 'Connectionless'and 'Stateless'. Lots of problems may occur if the scheme of transaction processing based on the LAN environment is directly applied to the web environment. Especially for long transactions of updating spatial data, it is very difficult to control the concurrency among clients and to keep the consistency of the server data. This paper proposes a solution of keeping consistency during updating directly spatial data in the client-side by resolving the Dormancy Region Lock problem caused by the 'Connectionless'and 'Stateless'feature of the HTTP protocol. The RX(Region-eXclusive) lock and the periodically sending of ALIVE_CLIENTi messages can solve this problem. The protocol designed here is verified as effective enough through implementing in the main memory spatial database system, called CyberMap.

• The Journal of the Korea Contents Association
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• v.7 no.11
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• pp.69-75
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• 2007

In this paper, we propose a new distributed processing scheme to support MMORPG (Massively Multiplayer Online Role-Playing Games). But existing distributed game servers have some problems such as hotspot, congestion, server failure problems, and so on. To solve such problems, our proposed scheme begins by splitting the large virtual world into smaller regions, each region handled by a different server. We present a scheme that reduces the bandwidth requirements for both game servers and clients. Also our scheme allows seamless interaction among players residing on areas handled by different servers. We show an excellence of the proposed solution through various experiments.

• Fire Science and Engineering
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• v.27 no.6
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• pp.83-88
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• 2013

Catastrophic disasters are sprouting out recently, i.e., the radiation leaks and the hydrofluoric acid gas leaks, etc. The restoration work for these kinds of disasters is very harmful and dangerous for human beings to handle themselves, thus allowing manless robots to fly the reconnaissance planes over to the disaster stricken areas and do the necessary work instead. For this endeavor and purpose, we created and tested an intelligent robot that can inspect those areas, using Mbed (ARM processor) technology temperature sensors and gas sensors aided by CAM (Computer-Aided Manufacturing) cameras. Also, HTTP Server, PC, androids and their combined efforts allow their remote controlled operation from far away with timing control. These intelligent robots can be on duty for 24 hours, minimizing the accidents and crimes and what not, and can respond more quickly when these misfortunes actually happen. We can anticipate the economic effects as well, derived from the reduced needs for hiring human resources.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.659-662
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• 2012

In this paper, the service system the urgent of the danger area or the managed object region is proposed whether the system is autonomously the police or situation where it informs through the police car and it can convey the contextual information or not. In case the nodes location is continuously confirmed from the gateway and it queues and the event is generated in the server of system whether it is the situation, or not the system to be proposed transmits the event triggered message and system transmitting the video message to the nearby which the event is generated node. As a result of the test, in case the event was generated in the server whether it was the situation, or not it confirmed to transmit the video message as the route where it is stored in the server.

• The KIPS Transactions:PartB
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• v.12B no.4 s.100
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• pp.451-458
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• 2005

The transcoding is a solution which is able to adapt to heterogeneous clients of requesting a different playback rate of multimedia data. Thus, The transcoding needs decoding and encoding. In general, previous studies to reduce complexity have a problem, the degradation of visual quality On the contrary, previous studies to reduce the degradation of visual quality lead to heavy computation. Thus, many researchers have studied a solution between the complexity and the degradation of visual quality. But until now, most researches of this region have dealt with the transcoder itself, such researches about a server's assistance to improve the performance of transcoder is rarely studied. In case of servicing multimedia data to heterogeneous clients which have low capabilities, the assistance of server side is able to reduce frames with processing in the transcoder and improve the performance of the transcoder. Thus in this paper, we propose the frame-skipping transcoder system architecture that takes into consideration transcoder and server side to reduce the complexity of the transcoder.

• Journal of the Korea Society of Computer and Information
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• v.15 no.6
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• pp.19-27
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• 2010

An region of interest processing technique is to handle preferentially some part of an image dynamically according to region of interest of the users in JPEG2000 image. A small image is not important, but in a big image the specified region that the user indicated has to be handled preferentially because it takes long time to display the whole image. If the user indicates a region of the outline image, the browser masks the region and sends the mask information to the source that transmitted the image. The server which got the mask information preferentially sends the code blocks matching the masks. Here, quickly generating mask information is important, so, in this paper using predefined 48 mask patterns, selecting one of the patterns according to the distribution of ROI(Region-of-Interest) and background, we remarkably reduced the time computing the mask region. Blocks that the patterns are applied are the blocks mixed of ROI and background in a block. If a whole block is an ROI or a background, these patterns are not applied. As results, comparing to the method that precisely handles ROI and background, the quality is unsatisfactory but the processing time remarkably reduced.

• Journal of the HCI Society of Korea
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• v.2 no.1
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• pp.1-12
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• 2007

In this paper, we propose a video service system that reflects user interaction in the multimedia contents to increase user satisfaction in the restricted content consumption environment. The proposed system is based on the multiple ROI(Region of Interest) coding in H.264/AVC Scalable Video Coding (SVC). The proposed system provides scalable video quality by adopting SVC. And by bidirectional communication between user and video server, it enables user to select meaningful ROI among multiple ROIs by user interaction. To verify the usefulness of the proposed system, we demonstrate it with a test-bed on which user interactive ROIs are implemented.

• Journal of KIISE:Databases
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• v.33 no.3
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• pp.283-298
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• 2006

The TPR-tree is the time-parameterized indexing scheme that supports the querying of the current and projected future positions of such moving objects by representing the locations of the objects with their coordinates and velocity vectors. If this index is, however, used in environments that directions and velocities of moving objects, such as vehicles, are very often changed, it increases the communication cost between the server and moving objects because moving objects report their position to the server frequently when the direction and the velocity exceed a threshold value. To preserve the communication cost regularly, there can be used a manner that moving objects report their position to the server periodically. However, the periodical position report also has a problem that lineal time functions of the TPR-tree do not guarantee the accuracy of the object's positions if moving objects change their direction and velocity between position reports. To solve this problem, we propose the query processing scheme and the data structure using road networks for predicting uncertainty positions of moving objects, which is reported to the server periodically. To reduce an uncertainty of the query region, the proposed scheme restricts moving directions of the object to directions of road network's segments. To remove an uncertainty of changing the velocity of objects, it puts a maximum speed of road network segments. Experimental results show that the proposed scheme improves the accuracy for predicting positions of moving objects than other schemes based on the TPR-tree.

• KIPS Transactions on Computer and Communication Systems
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• v.7 no.8
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• pp.195-202
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• 2018

With the development of location-based applications such as smart phones and GPS navigation, active research is being conducted to protect location and trajectory privacy. To receive location-related services, users must disclose their exact location to the server. However, disclosure of users' location exposes not only their locations but also their trajectory to the server, which can lead to concerns of privacy violation. Furthermore, users request from the server not only location information but also multimedia information (photographs, reviews, etc. of the location), and this increases the processing cost of the server and the information to be received by the user. To solve these problems, this study proposes the EGTC (Enhanced Grid-based Trajectory Cloaking) technique. As with the existing GTC (Grid-based Trajectory Cloaking) technique, EGTC method divides the user trajectory into grids at the user privacy level (UPL) and creates a cloaking region in which a random query sequence is determined. In the next step, the necessary information is received as index by considering the sub-grid cell corresponding to the path through which the user wishes to move as c(x,y). The proposed method ensures the trajectory privacy as with the existing GTC method while reducing the amount of information the user must listen to. The excellence of the proposed method has been proven through experimental results.