• Journal of the Korea Society of Computer and Information
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• v.7 no.2
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• pp.79-86
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• 2002

This paper presents a low power scheduling and allocation algorithm for multiple supply voltage. The proposed supply voltage scheduling algorithm determines the control step to execute a possible the operation experimentally using another supply voltage level. Also, the switching activity using component library. and the supply voltage allocation method uses the graph coloring technique for low power, the proposed algorithm Proves the effect through various high level benchmark examples to adopt a multiple supply voltage scheduling algorithm for low power.

• IE interfaces
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• v.16 no.2
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• pp.185-194
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• 2003

This paper deals with a realistic production scheduling under a make-to-order production environment. The practical case is studied on the transformer winding process in the 'H' company. The transformer winding is a process that rolls a coil that is coated with an electric insulation material in order to generate the required voltage using the voltage fluctuation. This process occupies an important position among the production processes in the transformer manufacturing company. And this process is composed of parallel machines with different performances according to the voltage capacity and winding type. In this paper, we propose a practical heuristic algorithm for production scheduling to satisfy the customer’s due date under a make-to-order production environment. Also, we implement the production scheduling system based on the proposed heuristic algorithm. Consequently, the proposed heuristic algorithm and the implemented production scheduling system are currently working in the transformer production factory of the ‘H’ company.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.3
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• pp.421-428
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• 2008

The DVS(Dynamic Voltage Scaling) technique is the method to reduce the dynamic energy consumption. As using slack times, it extends the execution time of the big load operations by changing the frequency and the voltage of variable voltage processors. Researches, that controlling the energy consumption of the processors and the data transmission among processors by controlling the bandwidth to reduce the energy consumption of the entire system, have been going on. Since operations in multiprocessor systems have the data dependency between processors, however, the DVS techniques devised for single processors are not suitable to improve the energy efficiency of multiprocessor systems. We propose the new scheduling algorithm based on DVS for increasing energy efficiency of multiprocessor systems. The proposed DVS algorithm can improve the energy efficiency of the entire system because it controls frequency and voltages having the data dependency among processors.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.11C
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• pp.1132-1138
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• 2002

This paper proposes a reducing power consumption of a scheduling algorithm for optimal selection of supply voltage. In scheduling of reduction power consumption, we determine the control steps of operations to be executed by exploiting the possibility of using variable voltage levels to reduce power consumption. In the optimal selection of supply voltage binding, we minimize the main factor of the power consumption of the switching activity on the registers using a graph coloring technique. From a set of experiments using high-level benchmark examples, we show that the proposed algorithm prefer to use optimal selection supply voltages rather than uniformed single voltage is effective in reducing power consumption.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.11
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• pp.601-610
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• 2002

Intra-task voltage scheduling (IntraVS), which adjusts the supply voltage within an individual task boundary, is an effective technique for developing low-power applications. In this paper, we propose a novel intra-task voltage scheduling algorithm for hard real-time applications based on average-case execution time. Unlike the conventional IntraVS algorithm where voltage scaling decisions are based on the worst-case execution cycles, tile proposed algorithm improves the energy efficiency by controlling the execution speed based on average-case execution cycles while meeting the real-time constraints. The experimental results using an MPEG-4 decoder program show that the proposed algorithm reduces the energy consumption by up to 34% over conventional IntraVS algorithm.

• Journal of Korea Multimedia Society
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• v.11 no.5
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• pp.641-650
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• 2008

As portable devices are used widely, power management algorithm is essential to extend battery use time on small-sized battery power. Although many methods have been proposed, they assumed the voltage transition overhead was negligible or was considered partially. However, the voltage transition overhead might not guarantee to schedule real-time tasks in portable multimedia systems. This paper proposes the adaptive power-aware algorithm to minimize the power consumption by considering the voltage transition overhead. It selects only a few discrete frequencies from the whole frequencies of a system and adjusts the interval between two consecutive frequencies based on the system utilization to reduce the number of frequency change. This algorithm saves the power consumption about 10 to 25 percent compared to a CC RT-DVS method and a frequency-smoothing method.

• Journal of Computing Science and Engineering
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• v.7 no.1
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• pp.30-43
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• 2013

Multicore and multiprocessor systems with dynamic voltage scaling architectures are being used as one of the solutions to satisfy the growing needs of high performance applications with low power constraints. An important aspect that has propelled this solution is effective task/application scheduling and mapping algorithms for multiprocessor systems. This work proposes an energy aware, offline, probability-based unified scheduling and mapping algorithm for multiprocessor systems, to minimize the number of processors used, maximize the utilization of the processors, and optimize the energy consumption of the multiprocessor system. The proposed algorithm is implemented, simulated and evaluated with synthetic task graphs, and compared with classical scheduling algorithms for the number of processors required, utilization of processors, and energy consumed by the processors for execution of the application task graphs.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.7
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• pp.22-28
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• 2009

As multiprocessors have been widely adopted in embedded systems, task computation energy consumption should be minimized with several low power techniques supported by the multiprocessors. This paper proposes an energy-aware task scheduling algorithm that adopts both dynamic voltage scaling and power shutdown in multiprocessor environments. Considering the timing and energy overhead of power shutdown, the proposed algorithm performs an iterative task assignment and task ordering for multiprocessor systems. In this case, the iterative priority-based task scheduling is adopted to obtain the best solution with the minimized total energy consumption. Total energy consumption is calculated by considering a linear programming model and threshold time of power shutdown. By analyzing experimental results for standard task graphs based on real applications, the resource and timing limitations were analyzed to maximize energy savings. Considering the experimental results, the proposed energy-aware task scheduling provided meaningful performance enhancements over the existing priority-based task scheduling approaches.

• Journal of Electrical Engineering and Technology
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• v.11 no.2
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• pp.329-337
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• 2016

With the increasing deployment of distributed generators in the distribution system, a very large search space is required when dynamic programming (DP) is applied for the optimized dispatch schedules of voltage and reactive power controllers such as on-load tap changers, distributed generators, and shunt capacitors. This study proposes a new optimal voltage and reactive power scheduling method based on dynamic programming with a heuristic searching space reduction approach to reduce the computational burden. This algorithm is designed to determine optimum dispatch schedules based on power system day-ahead scheduling, with new control objectives that consider the reduction of active power losses and maintain the receiving power factor. In this work, to reduce the computational burden, an advanced voltage sensitivity index (AVSI) is adopted to reduce the number of load-flow calculations by estimating bus voltages. Moreover, the accumulated switching operation number up to the current stage is applied prior to the load-flow calculation module. The computational burden can be greatly reduced by using dynamic programming. Case studies were conducted using the IEEE 30-bus test systems and the simulation results indicate that the proposed method is more effective in terms of saving electric charges and improving the voltage profile than loss minimization.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11B
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• pp.1631-1639
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• 2010

This paper proposes a scheduling algorithm that can reduce the power consumed for execution of application programs and the communication cost incurred due to dependencies among tasks. The proposed scheduling algorithm can increase energy efficiency of the DVS(Dynamic Voltage Scaling) by estimating laxity usage during scheduling, making up for conventional algorithms that apply the DVS after scheduling. Energy efficiency can be increased by applying the proposed algorithm to complex multimedia applications. Experimental results show that energy consumptions for executing HD MPEG4, MotionJPEG codec, MP3, and Wavelet have been reduced by 11.2% on the average, when compared to conventional algorithms.