• Journal of Internet Computing and Services
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• v.7 no.4
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• pp.79-90
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• 2006

Data broadcasting is an efficient method for disseminating data, and is widely accepted in the database applications of mobile computing environments because of its asymmetric communication bandwidth between a server and mobile clients. This requires new types of concurrency control mechanism to support mobile transactions executed in the mobile clients, which have low-bandwidths toward the server. In this paper, we propose an OCC/DTA (Optimistic Concurrency Control with Dynamic Time-stamp Adjustment) protocol that can be efficiently adapted to mobile computing environments. The protocol reduces communication overhead by using client-side validation procedure and enhances transaction throughput by adjusting serialization order without violating transaction semantics. We show that the proposed protocol satisfies data consistency requirements, and simulate that this protocol can improve the performance of mobile transactions in data broadcasting environments.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.1344-1347
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• 2012

Mobile Cloud Computing services anywhere, anytime access to the Internet via a mobile terminal means to provide services, speakers are called Mobiloud. Computing processing power limitations of mobile devices, storage, due to space constraints, the tasks handled by mobile devices and data processing services to move to cloud environments. In recent years, smartphone, tablet PC and mobile device companies and individuals to spread and spread, and the content of the accelerating cloud painters, mobile cloud that can communicate with each other requires a standard service.

• Journal of KIISE:Databases
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• v.31 no.3
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• pp.287-296
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• 2004

Recently, various location-based services are becoming very popular in mobile environments. In this paper, we propose a new concept of a frequent item set, called “associative class set”, for supporting the location-based service which uses a large quantity of a spatial database in mobile computing environments, and then present a new method for efficiently generating the associative class set. The associative class set is generated with considering the temporal relation of queries, the spatial distance of required objects, and access patterns of users. The result of our research can play a fundamental role in efficiently supporting location-based services and in overcoming the limitation of mobile environments. The associative class set can be applied by a recommendation system of a geographic information system in mobile computing environments, mobile advertisement, city development planning, and client cache police of mobile users.

• Korean Institute of Interior Design Journal
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• v.21 no.2
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• pp.186-196
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• 2012

Information technology has changed the human life as well as the societal and economic paradigm. New office environments have been proposed to cope with emerging changes and to support working performances by reducing costs of office operation and business. Recently, office environments have adopted ubiquitous computing with a focus on collaboration to promote real-time enterprises. They become equipped with various mobile devices and pervasive technologies in wireless networks. This study aims to propose a direction for the adoption of mobile and pervasive computing on the new office environment. We investigate relate works and analyze new office types including mobile offices, telework centers and home offices. Using a customized questionnaire, the current conditions of the office environments and officers' demands were investigated and analyzed. In the end, we propose the direction for a ubiquitous office environment with a focus on two attributes, ubiquity and mobility. This research will be a basis for the development of ubiquitous offices that support the professionalism of works in practices.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.6
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• pp.3254-3272
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• 2017

With the development of wireless access technologies and the popularity of mobile intelligent terminals, cloud computing is expected to expand to mobile environments. Attribute-based encryption, widely applied in cloud computing, incurs massive computational cost during the encryption and decryption phases. The computational cost grows with the complexity of the access policy. This disadvantage becomes more serious for mobile devices because they have limited resources. To address this problem, we present an efficient verifiable outsourced scheme based on the bilinear group of prime order. The scheme is called the verifiable outsourced computation ciphertext-policy attribute-based encryption scheme (VOC-CP-ABE), and it provides a way to outsource intensive computing tasks during encryption and decryption phases to CSP without revealing the private information and leaves only marginal computation to the user. At the same time, the outsourced computation can be verified by two hash functions. Then, the formal security proofs of its (selective) CPA security and verifiability are provided. Finally, we discuss the performance of the proposed scheme with comparisons to several related works.

• The Journal of Bigdata
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• v.4 no.1
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• pp.129-142
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• 2019

Construction projects have experienced many failures due to incomplete production environments. Thus, the purpose of this study is to use ICT resources leased during the construction period at the construction site and to introduce the Mobile Cloud Computing Service, which utilizes Cloud Computing Service and mobile devices such as smart phones, tablet PCs, and notebooks instead of physically wired communication networks. The characteristics of Mobile Cloud, such as rapid accuracy, shared collaboration, and ubiquity, will affect the social network among various construction site participants. we conducted empirical research on the introduction of Mobile Cloud to promote information exchange and convergence among the participants and mutual trust, ultimately improving the project performance.

• IEMEK Journal of Embedded Systems and Applications
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• v.10 no.4
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• pp.241-255
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• 2015

Recent network environment has been rapidly evolved to cloud computing environment based on the development of the Internet technologies. Furthermore there is an increasing demand on mobile cloud computing due to explosive growth of smart devices and wide deployment of LTE-based cellular networks. Thus mobile Desktop-as-a-Service(DaaS) could be a pervasive service for nomadic users. In addition, video streaming traffic is currently more than two-thirds of mobile traffic and ever increasing. All such trends enable that video streaming in mobile DaaS could be an important concern for mobile cloud computing. It should be noted that the performance of the Transmission Control Protocol(TCP) on cloud host servers greatly affects Quality of Service(QoS) of video streams for mobile users. With widely deployed Linux server platforms for cloud computing, in this paper, we conduct an experimental analysis of the twelve Linux TCP variants in mobile DaaS environments. The results of our experiments show that the TCP Illinois outperforms the other TCP variants in terms of wide range of packet loss rate and propagation delay over LTE-based wireless links between cloud servers and mobile devices, even though TCP CUBIC is usually used in default in the current Linux systems.

• Journal of Internet Computing and Services
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• v.6 no.5
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• pp.155-166
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• 2005

Currently, almost of all the Internet users have as many IDs as the number of sites they have subscribed for, The users should memorize and input every independent ID and password whenever they want to login to the system. Although ID management system is used to solve this problem, 10 and password management will become more complicated in the forthcoming ubiquitous computing environments because so many computers will be interconnected on various kinds of wired and wireless networks, Furthermore, it is not enough to use the existing single Circle of Trust (COT) ID management system for the forthcoming computing environments. To solve this problem, the paper proposes ID federation models in multiple COT domain and implements an ID federation system that can be scaled to mobile computing environment as well as wired computing environment. The proposed ID federation models has been verified to operate with no problem between the systems in different trust domains by doing the ID scaability test.

• The Transactions of the Korea Information Processing Society
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• v.6 no.1
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• pp.1-10
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• 1999

A mobile computing environment is one that support user's mobility through the wireless communication technology. Users access the database and get results what they want by running mobile transactions. To run the mobile transaction correctly and to maintain the consistency I database, we need a concurrency control method to schedule transactions, a caching method to manage the cache, and a recovery method to construct a fault tolerant system. A mobile computing system is based on the existing distributed system, but we can't use recovery methods of the existing distributed system directly because of the user's mobility and the features of wireless media. So this paper presents a recovery mechanism to construct a fault tolerant mobile computing systems. Especially. we develop and analyze a recovery algorithm for server failure among types of failure which can arise in mobile computing environments.

• The KIPS Transactions:PartC
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• v.16C no.3
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• pp.335-346
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• 2009

Mobile environments are evolving the main communication environment as a develops of communication technology. In mobile environments, sensitive information can be compromised on-line, so demand for security has increased. Also, mobile devices that provide various services are in danger from malware and illegal devices, phishing and sniffing etc, and the privacy. Therefore, MTM(Mobile Trusted Module) is developed and promoted by TCG(Trusted Computing Group), which is an industry standard body to enhance the security level in the mobile computing environment. MTM protects user privacy and platform integrity, because it is embedded in the platform, and it is physically secure. However, a security approach is required when secret data is migrated elsewhere, because MTM provides strong security functions. In this paper, we analyze the TCG standard and migration method for cryptographic key, then we propose a secure migration scheme for cryptographic key using key Backup/Recovery method.