The current scheme of access control judges the legality of each access based on immediate information without considering associate information hidden in a series of accesses. Due to the deficiency, access control systems do not efficiently limit attacks consist of ordinary operations. For trusted operating system developments, we extended RBAC and added negative procedural constraints to refuse those attacks. With the procedural constraints, the access control of trusted operating systems can discriminate attack trials from normal behaviors. This paper shows the specification of the extended concept and model, and presents simple analysis results.

In this paper, we develop asymptotic analysis and simulation models to better understand the characteristics of performance and energy consumption in a multi-core processor design in which dynamic voltage scaling is used. Our asymptotic model is derived using Amdahl's law, Rent's rule and power equations to derive the optimum number of cores and their voltage levels. Our model can predict the possible impact of different multi-core processor configurations on the performance and energy consumption for given workload characteristics (e.g. available parallelism) and process technology parameters (e.g. ratios of dynamic and static energies to total energy). Through the asymptotic analysis and optimization based on the models, we can observe an asymptotic relationship between design parameters such as "the number of cores," "core size" and "voltage scaling strategies" of a multi-core architecture with regards to performance and energy consumption at an initial phase of the design.

The major concern at a branch point in asynchronous transfer mode (ATM) networks for point-to-multipoint available bit rate (ABR) services is how to consolidate backward resource management (BRM) cells from each branch for a multicast connection. In this paper, we propose an efficient feedback consolidation algorithm based on an adaptive dynamic threshold (ADT) to eliminate consolidation noise and to reduce consolidation delay. The main idea of the ADT algorithm is that each branch point estimates the ABR traffic condition of the network through virtual queue estimation. Simulation results show that the proposed ADT algorithm can achieve a faster response in congestion status and a higher link utilization compared with the previous works.

Several structured peer-to-peer networks have been created to solve the scalability problem of previous peer-to-peer systems such as Gnutella and Napster. These peer-to-peer networks which support distributed hash table functionality construct a sort of structured overlay network, which can cause a topology mismatch between the overlay and the underlying physical network. To solve this mismatch problem, we propose a topology-aware hierarchical overlay framework for DHTs. The hierarchical approach for the overlay is based on the concept that the underlying global Internet is also a hierarchical architecture, that is, a network of networks. This hierarchical approach for the overlay puts forth two benefits: finding data in a physically near place with a high probability, and smaller lookup time. Our hierarchical overlay framework is different from other hierarchical architecture systems in a sense that it provides a specific self-organizing grouping algorithm. Our additional optimization schemes complete the basic algorithm which constructs a hierarchical structure without any central control.

The crucial handover elements in wireless ATM networks are handover delay and handover efficiency. Since the research about the handover in wireless ATM has until now focused mainly on minimizing handover delay, the results have shown the inefficiency of network resources. In broadband wireless ATM networks, handover efficiency is critical to network capacity. In this paper, we propose a new handover scheme based on a partial path rerouting scheme called the delay limited best-fit backtracking scheme. The scheme searches for the crossover switch that limits handover delay and at the same time maximizes handover efficiency. It uses a new crossover switch searching method, which is an adaptive backtracking searching method that uses a best-fit search manner, to search for the optimal crossover switch that satisfies the given crossover switch condition. We evaluated the performance of proposed handover scheme, and show that the suggested scheme can improve handover efficiency more than other handover schemes.

This paper presents the Coloured Petri Net modeling for security analysis of the Extended Role Based Access Control systems.