• Journal of Convergence Society for SMB
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• 제4권1호
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• pp.7-15
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• 2014

In this paper, we propose an efficient routing protocol to achieve an optimal route searching process of the network lifetime by balancing power consumption per node. The proposed protocols aim at finding energy-efficient paths at low protocol power. In our protocol, each intermediate node keeps power level and branch number of child nodes and it transmits the data the nearest neighbor node. Our protocol may minimize the energy consumption at each node, thus prolong the lifetime of the system regardless of the location of the sink outside or inside the cluster. In the proposed protocol for inter-cluster communication, a cluster head chooses a relay node from its adjacent cluster heads according to the node's residual energy and its distance to the base station. Simulation results show that proposed protocol successfully balances the energy consumption over the network, and achieves a remarkable network lifetime improvement as highly as 7.5%.

• Journal of the Korean Solar Energy Society
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• 제32권6호
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• pp.11-21
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• 2012

In the normal office building, the energy consumption to maintain the reasonable intensity of illumination for the work by using the artificial illumination occupies 30% or greater of the whole building electric energy consumption. If the dependability of the artificial illumination is dropt by positively using the natural lighting from the outside, the large amount of electrical energy can be saved, in addition the more nice visual environment for work can be created. Daylight is lighting source that most closely match visual response of the human, because sunlight and skylight achieve the harmony. For this reason, the daylight of small amount than amount of the artificial lighting source also can give the same effect in work activities of human. In addition, if there is daylight at the window of the building, the energy can be saved by controlling the artificial lighting. In this paper, in the building using the photovoltaic power generation analyze the correlation between the amount of energy generated by photovoltaic and indoor illumination and this was proved through the simulation with Relux 2010. In addition, the amount of daylight inflow in the room and distribution was drawn by the equation and the ratio for the sectional dimming control of each lighting equipment was predicted and the energy saving amount according to this was calculated. As a result, the indoor illumination was satisfied with recommended illumination value of the office and consumption power could be reduced approximately with 20~70%.

• Journal of the Korean Society for Precision Engineering
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• 제32권4호
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• pp.339-344
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• 2015

Machine tools are one of the energy-intensive equipment used in the manufacturing industry. The importance of energy has increased and the machine tools are required to be energy-efficient. The servo systems of the machine tool consume electrical power to rotate a spindle and to feed a tool during machining. Servo system consumes a lot of energy when the machine tool is operated. The energy consumption pattern of each axis needs to be investigated in order to optimize the machining process with regard to energy cost. In this paper, an energy monitoring system is developed considering various measuring points of servo system in order to grasp the energy consumption pattern of each axis.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.138.6-138
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• 2001

In recent years, as the battery-powered portable systems such as cellular phone, personal digital assistant (PDA) are widely used, power consumption comes to be a top-priority design concerns. Because those embedded systems become more and more complex than ever and they are operated under severe power and energy constrains, long battery lifetime with a limited energy is very critical. Even though there are various levels of energy optimization techniques, system level techniques are mainly focused on, for their stronger impact on power consumption of the overall system than traditional techniques : circuit level, switch level, architecture level, etc. In this technique, operating system (OS) plays the most important role in the system because it controls ...

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• 제9권3호
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• pp.410-425
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• 1997

Buildings are mostly under part load conditions causing an inefficient system operation in terms of energy consumption. It is critical to operate building air-conditioning system with a scientific or optimal manner which minimizes energy consumption and maintains thermal comfort by matching building sensible and latent loads. Little research has been performed in developing general methodologies for the optimal operation of air-conditioning system. Based on this research motivation, system simulation program was developed by adopting various equipment operating strategies which are energy efficient especially for humidity control in summer. A numerical optimization technique was utilized to search optimal solution for multi-independent variables and then linked to the developed system simulation model within a mam program. The main goal of the study is to provide a systematic framework and guideline for the optimal operation of air-conditioning system focusing on air-side. For given cooling loads and ambient outdoor conditions the optimal operating strategies of a commercial building are determined by minimizing a constrained objective function by a nonlinear programming technique. Desired space setpoint conditions were found through evaluating the trade-offs between comfort and system power consumption. The results show that supply airflow rate and compressor fraction play main roles in the optimization process. It was found that variable setpoint optimization technique could produce lower indoor humidity level demanding less power consumption which will be benefits for building applications of humidity problem.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제31권12B호
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• pp.1028-1036
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• 2006

Energy conservation is an important issue in wireless networks, especially for self-organized, low power, low data-rate impulse-radio ultra-wideband (IR-UWB) networks, where every node is a battery-driven device. To conserve energy, it is necessary to turn node into sleep state when no data exist. This paper addresses the energy consumption analysis of Direct-Sequence (DS) versus Time-Hopping (TH) multiple accesses and two kinds of sleeping protocols (slotted and unslotted) in PHY-MAC for Un networks. We introduce an analytical model for energy consumption or a node in both TH and DS multiple accesses and evaluate the energy consumption comparison between them and also the performance of the proposed sleeping protocols. Simulation results show that the energy consumption per packet of DS case is less than TH case and for slotted sleeping is less than that of unslotted one for bursty load case, but with respect to the load access delay unslotted one consumes less energy, that maximize node lifetime.

• Journal of Communications and Networks
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• 제14권1호
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• pp.75-90
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• 2012

Thin client computing trades local processing for network bandwidth consumption by offloading application logic to remote servers. User input and display updates are exchanged between client and server through a thin client protocol. On wireless devices, the thin client protocol traffic can lead to a significantly higher power consumption of the radio interface. In this article, a cross-layer framework is presented that transitions the wireless network interface card (WNIC) to the energy-conserving sleep mode when no traffic from the server is expected. The approach is validated for different wireless channel conditions, such as path loss and available bandwidth, as well as for different network roundtrip time values. Using this cross-layer algorithm for sample scenario with a remote text editor, and through experiments based on actual user traces, a reduction of the WNIC energy consumption of up to 36.82% is obtained, without degrading the application's reactivity.

• Journal of Information Processing Systems
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• 제17권3호
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• pp.489-504
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• 2021

By distributing computing tasks among devices at the edge of networks, edge computing uses virtualization, distributed computing and parallel computing technologies to enable users dynamically obtain computing power, storage space and other services as needed. Applying edge computing architectures to Internet of Vehicles can effectively alleviate the contradiction among the large amount of computing, low delayed vehicle applications, and the limited and uneven resource distribution of vehicles. In this paper, a predictive offloading strategy based on the MEC load state is proposed, which not only considers reducing the delay of calculation results by the RSU multi-hop backhaul, but also reduces the queuing time of tasks at MEC servers. Firstly, the delay factor and the energy consumption factor are introduced according to the characteristics of tasks, and the cost of local execution and offloading to MEC servers for execution are defined. Then, from the perspective of vehicles, the delay preference factor and the energy consumption preference factor are introduced to define the cost of executing a computing task for another computing task. Furthermore, a mathematical optimization model for minimizing the power overhead is constructed with the constraints of time delay and power consumption. Additionally, the simulated annealing algorithm is utilized to solve the optimization model. The simulation results show that this strategy can effectively reduce the system power consumption by shortening the task execution delay. Finally, we can choose whether to offload computing tasks to MEC server for execution according to the size of two costs. This strategy not only meets the requirements of time delay and energy consumption, but also ensures the lowest cost.

• Journal of the Korea Society of Computer and Information
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• 제13권7호
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• pp.165-172
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• 2008

There are many metrics when designing microprocessors. Especially, energy, power consumption and performance are the most fundamental metrics. Since these metrics are contradictory, microprocessor designers give more weight to some metrics than the other metrics. In this paper, we compare Intel Pentium 4 and Core2 Duo both qualitatively and quantitatively. Furthermore, we provide detailed comparison between Pentium 4 and Core2 Duo when running real benchmarks. Through performance counter of real processors, we calculate energy and power consumption. Performance metric is execution time. In experimental result, Core2 Duo consumes less energy and power. Moreover, performance of Core2 Duo is also better than that of Pentium 4. However, in case of bzip2 which is optimized in Pentium 4, Pentium 4 shows much better performance and lower energy and power consumption than Core2 Duo.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.257-258
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• 2015

Korean power consumption of the electrical supply problems due to excess demand is repeated every year, the interest in energy increasing social and personal cost has been subject to the number of ways to reduce this cost increases. Automatic doors and automatic door installation market is increasing every year and frequently, when used in general commercial and communal porch consumption based on average 300 times a day power is 70[W] degree is a monthly average usage is about 50.4[KW]. The level can not ignore the power consumption due to switching frequency is large. In this paper, by converting the energy to be discarded in the automatic doors to the inverter and the regenerative energy and to develop control systems for power regeneration to reduce the power consumption by utilizing automatic contact auxiliary power.