We Duke Cho

U-kitchen: application scenario

The research topic of U-spaces is drifting towards the practical implementation. We have presented application scenario of a ubiquitous kitchen environment. The scenario is made using some smart devices communicating to each other and sharing the context via a kitchen server. By addition of limited level of smartness in the appliances, ubiquitous services are developed that makes the job for an autonomous ubiquitous system far more easier and technical issues, less complex. One of our objectives in this paper is to increase the quality and reduce the link cost so that the convergence of large number of devices can be made possible.

Energy-Efficient clustering algorithm in wireless sensor networks

Clustering the sensor nodes is one of the most popular and effective topology control approaches in a wireless sensor network. Topology control balances load on sensor nodes, and increases network scalability and lifetime. In this paper, we propose a novel clustering approach that periodically elects cluster heads and assistant nodes together. The assistant nodes substitute for each cluster head to transmit sensor readings to the base station. In order to show the superiority of our clustering algorithm, we compare it with the existing clustering algorithms in terms of the lifetime of the sensor network. As a result, our experimental results show that the proposed clustering algorithm achieves about 10% ~ 40% performance improvements over the existing clustering algorithms in terms of lifetime.

Developing intelligent smart home by utilizing community computing

In Ubiquitous environment, system makes their own decision without or with minimized user interaction to provide required services to users. To fulfill this requirement the system needs to collect the proper information of surroundings and define how to react to the changes based on found information autonomously. To achieve this process, the system should equipped with three basic components which are sensing infrastructure, context aware or intelligent decision, and smart services. Main purpose of this research is how to enable this process efficiently and suggest the way of developing smart space. In this paper, we present Community Computing as the method of developing smart space and three components are briefly described. Also, three applicable scenarios and problems that might be happened at smart home are suggested and how community computing can be utilized to solve these problems is shown.

Adaptive fault monitoring in fault tolerant CORBA

A number of different kinds of applications developed on CORBA framework need fault tolerance in asynchronous distributed system or network environment, and it is important to quickly detect the faults. There exist various fault monitoring and detection algorithms that employ a timeout-based mechanism. However, they are occasionally inaccurate in unstable or overloaded system. The goal of the proposed algorithm is to enhance the accuracy of fault monitoring. This is achieved by promptly adjusting the timeout interval using the past elapsed time values accumulated. Additionally, we use asynchronous invocation to call ‘is_alive() method of monitorable object with a sequence number. Experiment on CORBA-compliant Orbix ORB confirms the effectiveness of the proposed scheme compared to the existing one.