• Journal of KIISE:Information Networking
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• v.36 no.4
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• pp.263-274
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• 2009

Decentralized group key management mechanisms offer beneficial solutions to enhance the scalability and reliability of a secure multicast framework by confining the impact of a membership change in a local area. However, many of the previous decentralized solutions reveal the plaintext to the intermediate relaying proxies, or require the key distribution center to coordinate secure group communications between subgroups. In this study, we propose a decentralized group key management scheme that features a mechanism allowing a service provider to deliver the group key to valid members in a distributed manner using the proxy cryptography. In the proposed scheme, the key distribution center is eliminated while data confidentiality of the transmitted message is provided during the message delivery process. The proposed scheme can support a secure group communication in dynamic network environments where there is no trusted central controller for the whole network and the network topology changes frequently.

• Journal of the Korean GEO-environmental Society
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• v.24 no.9
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• pp.33-40
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• 2023

The lateral load which is applied to the pile foundation supporting the superstructure during an earthquake is divided into the inertia force of the upper structure and the kinematic force of the ground. The inertia force and the kinematic force could cause failure to the pile foundation through different complex mechanisms. So it is necessary to predict and evaluate interaction of the ground-pile-structure properly for the seismic design of the foundation. The interaction is affected by the lateral behavior of the structure, the length of the pile, the boundary conditions of the head, and the relative density of the ground. Confining pressure and ground stiffness change accordingly when the relative density changes, and it results that the coefficient of subgrade reaction varies depending on each system. Horizontal bearing behavior and capacity of the pile foundation vary depending on lateral load condition and relative density of the sandy soil. Therefore, the 1g shaking table tests were conducted to confirm the effect of the relative density of the dried sandy soil to dynamic behavior of the group pile supporting the superstructure. The result shows that, as the relative density increases, maximum acceleration of the superstructure and the pile cap increases and decreases respectively, and the slope of the p-y curve of the pile decreases.