Joon-Sic Cho

Wireless sensors deliver the data to the Base Station which is collected and monitored at the interested environment. To efficiently transmit the data, some nodes are elected to aggregate the data locally and hierarchically. Recently many cluster-based approaches are proposed. In the proposed technologies, UDACH uses a clustering method which considers the energy of each node instead of selecting cluster head randomly like as LEACH. UDACH consists of three stages such as cluster construction, building a cluster head tree and transmitting the data to the base station. The cluster construction is to select cluster node. In the next stage, the cluster heads form tree structure to transmit multi-hop through the parent cluster head. However, if the parent cluster head is not selected appropriately, UDACH dissipates the energy because the total distance of transmission to the BS is longer. In this paper, we propose A Clustering Method of Enhanced Tree Establishment to construct tree structure for the optimized energy consumption. Through the simulation, we describe that the proposed scheme is more effective than LEACH and UDACH routing protocol.

Computer system is evolving rapidly to ubiquitous computing system. A smart home environment is a typical ubiquitous environment consisting of a network of computerized electronic appliances. Current smart home system provides context information on individual machinery and it responses only to user's passive requirement. Correspondingly, smart home technique does not offer user's authentication access control, and preservation. To emphasize these issues, we study using the environment information by access control method, or user's authentication service requirement. However, current techniques still contains weak points. They cannot establish a large scaled-policy and it cannot also provide various efficient authentication methods. In this research, we propose an integrated preservation system by using the security middleware to solve the problem.

Wireless sensor networks (WSNs) consist of small sensor nodes with constrained energy, memory and computation capabilities. They are often deployed in the unattended and hostile environment. Therefore sensor nodes are vulnerable to attacks such as node capture and collusion attack by adversaries. To protect the whole network, cryptographic techniques are necessary that pairwise key establishment is the essential procedure. It enables that sensor nodes can communicate to each other securely. However, it is impractical to use traditional key management techniques such as public key cryptography and key distribution center (KDC) because of the resource constraints of sensor nodes. This paper proposes a key distribution scheme, based on exclusion-based systems (EBSs) and t-degree bivariate polynomials. It is an energy-efficient dynamic key management scheme which performs localized rekeying to minimize overhead.