Yann-Hang Lee

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Many embedded systems operate under severe power and energy constraints. Voltage clock scaling is one mechanism by which energy consumption may be reduced: It is based on the fact that power consumption is a quadratic function of the voltage, while the speed is a linear function. In this paper, we show how voltage scaling can be scheduled to reduce energy(More)
Wireless sensor networks are a challenging field of research when it comes to security issues. Using low cost sensor nodes with limited resources makes it difficult for cryptographic algorithms to function without impacting energy consumption and latency. In this paper, we focus on key management issues in multi-hop wireless sensor networks. These networks(More)
Scaling down power supply voltage yields a quadratic reduction in dynamic power dissipation and also requires a reduction in clock frequency. In order to meet task deadlines in hard real-time systems, the delay penalty in voltage scaling needs to be carefully considered to achieve low power consumption. In this paper, we focus on dynamic reclaiming of early(More)
Energy constrained complex real-time systems are becoming increasingly important in defense, space, and consumer applications. In this paper, we present a sensible heuristic to address the problem of energy-efficient voltage scheduling of a hard real-time task graph with precedence constraints for a multi-processor environment. We show that consideration of(More)
This paper extends the traditional Service-Oriented Architecture (SOA) to a new Real-Time SOA (RTSOA) and proposes a framework for the new architecture, by providing real-time service modeling, design, code generation, simulation, deployment, execution, orchestration, and management. The concepts, architecture, and enabling technique are studied for(More)