• Journal of KIISE:Databases
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• v.34 no.1
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• pp.1-17
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• 2007

As XML is becoming a de facto standard for distribution and sharing of information, the need for an efficient yet secure access of XML data has become very important. To enforce the fine-level granularity requirement, authorization models for regulating access to XML documents use XPath which is a standard for specifying parts of XML data and a suitable language for both query processing. An access control environment for XML documents and some techniques to deal with authorization priorities and conflict resolution issues are proposed. Despite this, relatively little work has been done to enforce access controls particularly for XML databases in the case of query access. Developing an efficient mechanism for XML databases to control query-based access is therefore the central theme of this paper. This work is a proposal for an efficient yet secure XML access control system. The basic idea utilized is that a user query interaction with only necessary access control rules is modified to an alternative form which is guaranteed to have no access violations using tree-aware metadata of XML schemes and set operators supported by XPath 2.0. The scheme can be applied to any XML database management system and has several advantages over other suggested schemes. These include implementation easiness, small execution time overhead, fine-grained controls, and safe and correct query modification. The experimental results clearly demonstrate the efficiency of the approach.

• Journal of Convergence for Information Technology
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• v.8 no.5
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• pp.69-75
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• 2018

The purpose of access control is to prevent computing resources from illegal behavior such as leakage, modification, and destruction by unauthorized users. As the cloud computing environment is expanded to resource sharing services using virtualization technology, a new security model and access control technique are required to provide dynamic and secure cloud-based computing services. The virtualization management convergence access control model provides a flexible user authorization function by applying the dynamic privilege assignment function to the role based access control mechanism. In addition, by applying access control mechanism based on security level and rules, we solve the conflict problem in virtual machine system and guarantee the safeness of physical resources. This model will help to build a secure and efficient cloud-based virtualization management system and will be expanded to a mechanism that reflects the multi-level characteristics.

• Journal of Korea Multimedia Society
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• v.13 no.1
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• pp.133-142
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• 2010

As the ubiquitous technology has penetrated into almost every aspect of modern life, the research of the security technology to solve the weakness of security in the ubiquitous environment is received much attention. Because, however, today's security systems are usually based on the fixed rules, many security systems can not handle diverse situations in the ubiquitous environment appropriately. Although many existing researches on context aware security service are based on ACL (Access Control List) or RBAC (Role Based Access Control), they have an overhead in the management of security policy and can not manipulate unexpected situations. Therefore, in this paper, we propose a context-aware security service providing multiple authentications and authorization from a security level which is decided dynamically in a context-aware environment using FCM (Fuzzy C-Means) clustering algorithm and Fuzzy Decision Tree. We show proposed model can solve typical conflict problems of RBAC system due to the fixed rules and improve overhead problem in the security policy management. We expect to apply the proposed model to the various applications using contextual information of the user such as healthcare system, rescue systems, and so on.

• Journal of the Korea Society of Computer and Information
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• v.11 no.5 s.43
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• pp.127-137
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• 2006

We propose two phase filtering scheme to develop an efficient mechanism for XML databases to control query-based access. An access control environment for XML documents and some techniques to deal with fine-grained authorization priorities and conflict resolution issues are proposed. Despite this, relatively little work has been done to enforce access controls particularly for XML databases in the case of query-based access. The basic idea utilized is that a user query interaction with only necessary access control rules is modified to an alternative form through a query optimization technique, which is guaranteed to have no access violations using tree-aware metadata of XML schemas. The scheme can be applied to any XML database management system and has several advantages such as small execution time overhead, fine-grained controls, and safe and correct query modification. The experimental results clearly demonstrate the efficiency of the approach.

• Journal of Korean Classical Literature and Education
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• no.32
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• pp.261-285
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• 2016

Saseol-sijo, a form of sijo with longer verses, still affords pleasure to modern readers, even when it is read without the original performance context. In this study, I focused on Saseol-sijo that induces laughter through exaggeration and caricature while singing about eagerly waiting for a lover who has left. These texts describe concurrently the emotions that are contradictory to each other, such as nostalgia and laughter. In addition, this feature reflects human's inner emotions that are not unified but rather change dynamically. Craving creates a sense of nostalgia, and also produces a comical element in nostalgia, so that nostalgia and laughter can be co-exist without conflict. In this study, 'semiotic square' was applied as the framework for interpreting the Saseol-sijo, which demonstrates the coexistence of inconsistent meanings. As a result, a Saseol-sijo which sings about waiting for a lover can be interpreted through contraires such as prohibition and authorization, craving and concerns, exposure and concealment and concentration and dispersion. The nostalgic laughter in Saseol-sijo is generally based on the conflict between the craving self and the restrictive world. A character consumed by craving may seem ridiculous and pathetic in the view of others. However, people in general would find sympathetic humor and identify with characters who portray their weaknesses or repeat their mistakes. After all, this is the laughter of compassion and reflection which Saseol-sijo evoke.