• Citations Per Year
Learn More
Spatial databases have been increasingly and widely used in recent years. The R-tree proposed by Guttman is probably the most popular dynamic index structure for eciently retrieving objects from a spatial database according to their spatial locations. However, experiments show that only about 70% storage utilization can be achieved in Guttman's R-tree and(More)
User authentication and access control are both necessary mechanisms for data protection in a computer system. Traditionally, they are implemented in different modules. In this paper, a new solution is presented to provide both user authentication and access control in a single module to avoid any possible security breach between these two protection(More)
A metering scheme enables a web server to measure the number of visits from clients. In addition, a proof needs to be presented by the server as evidence corresponding to this measured number. In this letter, we propose an efficient metering scheme that incorporates the hash-chaining technique and the digital signature algorithm to provide a nonrepudiation(More)
In a group-oriented threshold cryptosystem, each group, instead of each individual member within the group, publishes a single group public key. An outsider can use this group public key to send encrypted messages to the group. However, the received encrypted messages can only be decrypted properly when the number of participating members is larger than or(More)
Vertical thin-GaN LED was successfully fabricated on the GaN LED epi-layers grown on the patternedsapphire substrate with the pyramidal pattern by low-temperature Cu/Sn/Ag wafer bonding at 150 C. An inverted pyramidal pattern formed on the n-GaN surface after the GaN epi-layer was transferred onto Si wafer, which resulted from the pyramidal pattern on the(More)
  • 1