• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권4호
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• pp.1655-1673
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• 2018

Mobile computing environment is subject to the constraints of bounded network bandwidth, frequently encountered disconnections, insufficient battery power, and system asymmetry. To meet these constraints and to gain high scalability, data broadcasting has been proposed on data transmission techniques. However, updates made to the database in any broadcast cycle are deferred to the next cycle in order to appear to mobile clients with lower data currency. The main goal of this paper is to enhance the transaction performance processing and database currency. The main approach involves decomposing the main broadcast cycle into a number of sub-cycles, where data items are broadcasted as they were originally sequenced in the main cycle while appearing in the most current versions. A concurrency control method AOCCRBSC is proposed to cope well with the cycle decomposition. The proposed method exploits predeclaration and adapts the AOCCRB method by customizing prefetching, back-off, and partial backward and forward validation techniques. As a result, more than one of the conflicting transactions is allowed to commit at the server in the same broadcast cycle which empowers the processing of both update and read-only transactions and improves data currency.

• The KIPS Transactions:PartD
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• 제11D권1호
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• pp.211-218
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• 2004

Compared with the desktop, the MIDP on J2ME has many limitations on memory capacity, screen size, networking ability and processing speed. In addition, screens vary with device providers in size, and service platforms vary with mobile service providers. These factors require additional functions to server and cause overheads of the server. On this paper, we propose the wav to reduce overheads of the server and to overcome disadvantages of the J2ME clients, with the server that provides the service of data in XML document type and the client on MIDP that is developed including the kXML parser.

• Journal of Computing Science and Engineering
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• 제5권4호
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• pp.331-337
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• 2011

Recently, Virtual Desktop Infrastructure (VDI) has been widely adopted to ensure secure protection of enterprise data and provide users with a centrally managed execution environment. However, user experiences may be restricted due to the limited functionalities of thin clients in VDI. If thick client devices like laptops are used, then data leakage may be possible due to malicious software installed in thick client mobile devices. In this paper, we present Data Firewall, a security framework to manage and protect security-sensitive data in thick client mobile devices. Data Firewall consists of three components: Virtual Machine (VM) image management, client VM integrity attestation, and key management for Protected Storage. There are two types of execution VMs managed by Data Firewall: Normal VM and Secure VM. In Normal VM, a user can execute any applications installed in the laptop in the same manner as before. A user can access security-sensitive data only in the Secure VM, for which the integrity should be checked prior to access being granted. All the security-sensitive data are stored in the space called Protected Storage for which the access keys are managed by Data Firewall. Key management and exchange between client and server are handled via Trusted Platform Module (TPM) in the framework. We have analyzed the security characteristics and built a prototype to show the performance overhead of the proposed framework.

• Journal of Korea Multimedia Society
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• 제8권2호
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• pp.279-286
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• 2005

As the mobile environment has been generalized, data synchronization with mobile devices or mobile device and PC/server is required. To deal with the problem, the consortium was established by the companies, such as Motorola, Ericsson, and Nokia, and released SyncML(Synchronization Markup Language) as a standard of industrial area for interoperating with data synchronization and various transmission protocol. But, in synchronization process, when more than two clients requested data synchronization, data conflict can be happened. This paper studies the various conflict reasons that can happen in data synchronization processes and groups them systematically Through the analyzed information, we compose the Change Log Information(CLI) that can keep track of the chased information about synchronization. And we suggest an operation policy using CLI. Finally, we design an algorithm and adapt the policy as a method for the safety and consistency of data.

• Journal of the Korean Data and Information Science Society
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• 제22권2호
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• pp.269-285
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• 2011

Caching of frequently accessed data in mobile ad-hoc networks is a technique that can improve data access performance and availability. Cooperative caching, which allows sharing and coordination of cached data among several clients, can further enhance the potential of caching techniques. In this paper, we propose a cluster-based fuzzy cooperative caching method for mobile ad-hoc networks. The performance of the proposed caching method is evaluated through an analytical model and is compared to that of other cooperative caching methods.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국해양정보통신학회 2002년도 추계종합학술대회
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• pp.648-651
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• 2002

In data broadcast environments, data is disseminated from a small number of sewers to a much larger number of clients. The advancing technology of hardware and increasing needs of users' have extended a broadcast environments. A mobile environment use the data broadcasting. A user carrying a portable computer can submit the operations of a transaction. Some limitations such as the poor-resource, user mobility, and low bandwidth are difficult to apply traditional transaction management to the mobile environments. So, the new mechanisms are needed and one of the them is the correctness criteria of transactions. Serializability is the most used criteria, but serializability is not appropriate to the broadcast environment because unnecessary abort and additional message exchanges are occurred. Hence, in this paper, we will address the need of the new correctness criteria weaker than serializability and describe the adoption of the update consistency.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국정보통신학회 2013년도 추계학술대회
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• pp.173-176
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• 2013

This paper's questions, and an automatic scoring system written in HTML, and XML-based system that is at issue, the issue questions in a convenient offline automatically how to register, Easy to manage questions of issues, questions and problems of merging the PC and the mobile device in a place that can be obtained without taking the test system study. Server systems, and real-time registration questions merging problem, such as difficulty adjusting to the test required to build the system. Clients communicate with the server using the mobile device and the PC is required to take the exam in the View application, and responses are sent for treatment research.

• Proceedings of the Korea Information Processing Society Conference
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• 한국정보처리학회 2014년도 추계학술발표대회
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• pp.516-519
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• 2014

Cloud computing is an up-and-coming paradigm shift transforming computing models from a technology to a utility. However, security concerns related to privacy, confidentiality and trust are among the issues that threaten the wide deployment of cloud computing. With the advancement of ubiquitous mobile-based clients, the ubiquity of the model suggests a higher integration in our day to day life and this leads to a rise in security issues. To strengthen the access control of cloud resources, most organizations are acquiring Identity Management Systems (IDM). This paper presents one of the most popular IDM systems, specifically OAuth, working in the scope of Mobile Cloud Computing which has many weaknesses in its protocol flow. OAuth is a Delegated Authorization protocol, and not an Authentication protocol and this is where the problem lies. This could lead to very poor security decisions around authentication when the basic OAuth flow is adhered to. OAuth provides an access token to a client, so that it can access a protected resource, based on the permission of the resource owner. Many researchers have opted to implement OpenlD alongside OAuth so as to solve this problem. But OpenlD similarly has several security flows. This paper presents scenarios of how insecure implementations of OAuth can be abused maliciously. We incorporate an authentication protocol to verify the identities before authorization is carried out.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.370-372
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• 2014

This study questions, and an automatic scoring system written in HTML, and XML-based system that is at issue, the issue questions in a convenient offline automatically how to register, Easy to manage questions of issues, questions and problems of merging the PC and the mobile device in a place that can be obtained without taking the test system study. Server systems, and real-time registration questions merging problem, such as difficulty adjusting to the test required to build the system. Clients communicate with the server using the mobile device and the PC is required to take the exam in the View application, and responses are sent for treatment research.

• The Journal of the Korea Contents Association
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• 제10권7호
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• pp.98-106
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• 2010

In this research a food information contents available as well as for PC web and for mobile web users was designed. The web site providing service for PC web and mobile web clients focuses on offering data on individually matching food based on the member's information. The information obtained from the contents can be practically applied by mobile users helping them to take care of their health. This system focuses on wireless internet mobile users and offers various food menus with cooking videos and also information regarding food supplies for individually matching bibimpab recipes. It gives a good information about one of the most traditional Korean food bibimpab which is made of various kinds of vegetables and greens. It also contains nutrition balance information. Designing the web site as a web site available for wired wireless internet accesses makes it available at any place for mobile wireless internet users so that they can obtain all information regarding products and menu which are good for their health.