• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.977-980
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• 2008

유비쿼터스 컴퓨팅 환경에서는 사용자의 의도를 정확히 파악하고 그에 따른 정확한 정보 또는 서비스를 제공하는 것이 중요하다. 현재 보편적으로 사용 중인 키보드와 마우스는 직관성이 결여되었거나 휴대성이 부족하므로 유비쿼터스 환경에 적합한 새로운 입력 시스템이 필요하다. 본 논문에서는 2축 가속도 센서와 2개의 압력센서를 사용하여 무선 센서네트워크 환경에서 사용자의 손동작을 감지하여 컴퓨터를 직관적으로 사용할 수 있는 유비쿼터스 환경에 적합한 입력 시스템(u-Glove)을 설계 및 구현한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.05a
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• pp.1128-1131
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• 2008

현제의 서비스들은 점점 온라인화 되어 가고 있으며 특히 무선 통신의 발전에 따라 현대 사회인들은 다양한 모바일 기기들을 사용하여 여러 서비스를 제공 받고 있다. 하지만 서비스들을 제공하기 위한 기존 패스워드 기반의 사용자 인증은 스니핑과 피싱 및 악성코드에 의한 개인정보 유출 등으로 인하여 안전성을 보장받지 못하고 있다. 특히 모바일 단말기의 분실 및 불법적인 복제와 점차 증가하고 있는 모바일 악성코드로 인한 모바일 환경의 보안 위협은 기존의 소프트웨어 보안으로는 감당할 수 없게 되었다. 따라서 본 논문에서는 신뢰컴퓨팅을 위한 TCG의 보안기술로써 플랫폼 인증을 제공하는 MTM을 사용자 인증 모듈인 USIM과 연동하여 다양한 모바일 환경의 보안 위협에 대응할 수 있는 사용자 인증 방안을 제안한다.

• Information Systems Review
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• v.14 no.1
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• pp.37-65
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• 2012

This research aims to design and analyze a ubiquitous customer relationship management system based on near field communication which can be applied to stores in off-line environment. The existing customer relationship management system has been used mainly for stores in off-line environment to issue a royalty card, to stamp a seal on the purchase goods, and to manage the history of customers' visits and purchases. But, the existing system has two weaknesses; it makes difficult for a store manger not only to acquire a wealth of customer data but also to systematically manage the acquired data. In particular, the effectiveness and efficiency of the royalty card are questioned when a customer makes purchases in the store in that the customer frequently does not carry it or loses it. So, this research suggests a ubiquitous customer relationship management system where a tag for near field communications is attached to a store in off-line environment; a store manager can collect and manage easily customer's dada and customers can seamlessly acquire store's information. To do this, this research conducts the followings. First, we review the previous researches of customer relationship management to examine the concept of ubiquitous customer relationship management. Second, from the examination, we draw the factors to be considered in ubiquitous customer relationship management system based on near field communication. Third, we propose a scenario where the suggested system is used. Fourth, we analyze the participants' values and the process that will be used for the suggested system. Finally, we discuss the possibility of the application of this system to real business environment from various viewpoints.

• The KIPS Transactions:PartC
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• v.15C no.4
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• pp.297-302
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• 2008

In case of display a lot of information from mobile devices, those systems are being developed that display the information from mobile devices on remote devices such as TV using the mobile devices as remote controllers because it is difficult to display a lot of information on mobile devices due to their limited bandwidth and small screen sizes. A lot of cost is required to design and develop interfaces for these systems corresponding to each of remote display devices. In this paper, a mobile environment based remote display system for displays at real times is proposed for continuous monitoring of status data for unique 'Mote IDs'. Also, remote data are collected and monitored through sensor network devices such as ZigbeX by applying status perception based remote displays at real times through processing ubiquitous computing environment data, and remote display applications at real times are implemented through PDA wireless mobiles. The system proposed in this paper consists of a PDA for remote display and control, mote embedded applications programming for data collections and radio frequency, server modules to analyze and process collected data and virtual prototyping for monitoring and controls by virtual machines. The result of the implementations indicates that this system not only provides a good mobility from a human oriented viewpoint and a good usability of accesses to information but also transmits data efficiently.

• Journal of KIISE:Databases
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• v.33 no.1
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• pp.69-85
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• 2006

Broadcast has been often used to disseminate the frequently requested data efficiently to a large volume of mobile clients over a single or multiple channels. Conventional concurrency control protocols for mobile transactions are not suitable for the wireless broadcast environments due to the limited bandwidth of the up-link communication channel. In wireless broadcast environments, the server often broadcast different data items with different frequency to incorporate the data access patterns of mobile transactions. The previously proposed concurrency control protocols for mobile transactions in wireless broadcast environments are focused on the mobile transactions with uniform data access patterns. However, these protocols perform poorly when the data access pattern of update mobile transaction are not uniform but skewed. The update mobile transactions with skewed data access patterns will be frequently aborted and restarted due 4o the update conflict of the same data items with a high access frequency. In this paper, we propose an energy-efficient concurrence control protocol for mobile transactions with skewed data access as well as uniform data access patterns. Our protocol use a random back-off technique to avoid the frequent abort and restart of update mobile transactions. We present in-depth experimental analysis of our method by comparing it with existing concurrency control protocols. Our performance analysis show that it significantly decrease the average response time, the amount of upstream and downstream bandwidth usage over existing protocols.

• Journal of Korea Spatial Information System Society
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• v.7 no.1 s.13
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• pp.25-37
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• 2005

Recently, with the development of wireless communications and mobile computing, interest about mobile computing is rising. Mobile computing can be regarded as an environment where a user carries mobile devices, such as a PDA or a notebook, and shares resources with a server computer via wireless communications. A mobile database refers to a database which is used in these mobile devices. The mobile database can be used in the fields of insurance business, banking business, medical treatment, and so on. Especially, LBS(Location Based Service) which utilizes location information of users becomes an essential field of mobile computing. In order to support LBS in the mobile environment, there must be an Embedded Spatial MMDBMS(Main-Memory Database Management System) that can efficiently manage large spatial data in spatial mobile devices. Therefore, in this paper, we designed and implemented the Embedded Spatial MMDBMS, extended from the HSQLDB which is an existing MMDBMS for PC, to manage spatial data efficiently in spatial mobile devices. The Embedded Spatial MMDBMS adopted the spatial data model proposed by ISO(International Organization for Standardization), provided the arithmetic coding method that is suitable for spatial data, and supported the efficient spatial index which uses the MBR compression and hashing method suitable for spatial mobile devices. In addition, the system offered the spatial data display capability in low-performance processors of spatial mobile devices and supported the data caching and synchronization capability for performance improvement of spatial data import/export between the Embedded Spatial MMDBMS and the GIS server.

• Journal of Korea Spatial Information System Society
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• v.7 no.2 s.14
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• pp.47-56
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• 2005

Recently, with the rapid development of mobile computing, wireless positioning technologies, and the generalization of wireless internet, LBS (Location Based Service) which utilizes location information of moving objects is serving in many fields. In order to serve LBS efficiently, the location data server that periodically stores location data of moving objects is required. Formerly, GIS servers have been used to store location data of moving objects. However, GIS servers are not suitable to store location data of moving objects because it was designed to store static data. Therefore, in this paper, we designed and implemented an extended SLDS(Short-term Location Data Subsystem) for real-time Location Based Services. The extended SLDS is extended from the SLDS which is a subsystem of the GALIS(Gracefully Aging Location Information System) architecture that was proposed as a cluster-based distributed computing system architecture for managing location data of moving objects. The extended SLDS guarantees real-time service capabilities using the TMO(Time-triggered Message-triggered Object) programming scheme and efficiently manages large volume of location data through distributing moving object data over multiple nodes. The extended SLDS also has a little search and update overhead because of managing location data in main memory. In addition, we proved that the extended SLDS stores location data and performs load distribution more efficiently than the original SLDS through the performance evaluation.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.10
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• pp.1491-1497
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• 2013

Radio frequency identification (RFID) is an important and essential components of ubiquitous computing, with the development of wireless communication technologies and mobile computing environment. Recently, RFID becomes the mainstream application that helps fast handling and uniquely identifying the physical objects. It utilizes the electromagnetic energy for data transmission from a tag to a reader in the presence of arbitrary interference and noise. In order to employ the portable mobile RFID reader, a tag-collision problem between two or more adjacent tags should be considered. In this paper, we present the operation of RFID system in which numerous tags are present in the interrogation zone of a single reader at the same time. Since there may exist a number of tagged objects in the narrow area, multiple RFID tags may interfere each other, caused to degrade the data reliability and efficiency of the RFID system. In order to suppress interference signals from multiple neighboring tags, we present an application of Gold code for RFID communication system, which uses spread spectrum technique. In this RFID system, data bits are spreaded in each tags with the unique Gold code and the spreaded data bits are despreaded in the reader with the same Gold code. The performance analysis of the considered RFID anti-collision system is illustrated via computer simulation examples.

• Journal of KIISE:Databases
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• v.30 no.6
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• pp.606-628
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• 2003

Recently, there have been many research efforts reported in the literature that focus on the cache consistency problems of mobile clients resulting from their frequent disconnections with a server in mobile environments. To cope with this problem, a number of methods based on the invalidation report scheme has been proposed. However, these proposed methods are sensitive to the disconnection time of mobile clients and independent of the frequency of data updates in the server. As a result, although the number of data updated in the server is small, the traditional methods can not guarantee the cache consistency of mobile clients if their disconnection time is over the time period the invalidation report is allowed to cover. In this paper, we propose an efficient cache consistency method called CCI(Cost-based Cache Invalidation) for mobile clients that take into account not only the disconnection time but also the frequencies of data updates in the server We also present an in-depth experimental analysis by comparing CCI method with BT(Broadcasting Time stamp) method based on Invalidation Report.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.674-677
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• 2012

An operating system acts as an intermediary between your computer hardware and computer users to perform, that the user can run the program provides an environment in which. Therefore, the main purpose of the operating system having a computer available for your convenience and to effectively manage computer hardware. The popularization of the people who use computers, improve hardware performance, advent of the internet, popularity of wireless networks, Smartphone and Tablet PC appearance, advent of virtualization technologies and cloud computing, etc. began making changes to the operating system. In particular, cloud computing environments based on server virtualization and using a variety of wired and wireless devices with internet connection, a Web-based operating system was born. In this paper, the definition of a Web-based operating system, types and characteristics, an analysis of the pros and cons, and find out about the future prospects.