• Proceedings of the Korea Information Processing Society Conference
• /
• 2011.04a
• /
• pp.123-126
• /
• 2011

저전력 운전을 위해 정렬 알고리즘을 대상으로 알고리즘 복잡도와 에너지 소모 관련성을 분석하고 전력 효율을 향상시키도록 알고리즘을 수정 개발하여 실험하였다. 얻어진 결과는 향후 그린컴퓨팅 실현에 활용하고자 한다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.2
• /
• pp.504-521
• /
• 2016

Recently, energy harvesting technology has been integrated into wireless sensor networks to ameliorate the nodes' energy limitation problem. In theory, the wireless sensor node equipped with an energy harvesting module can work permanently until hardware failures happen. However, due to the change of power supply, the traditional hierarchical network routing protocol can not be effectively adopted in energy harvesting wireless sensor networks. In this paper, we improve the Low-Energy Adaptive Clustering Hierarchy (LEACH) protocol to make it suitable for the energy harvesting wireless sensor networks. Specifically, the cluster heads are selected according to the estimation of nodes' harvested energy and consumed energy. Preference is given to the nodes with high harvested energy while taking the energy consumption rate into account. The utilization of harvested energy is mathematically formulated as a max-min optimization problem which maximizes the minimum energy conservation of each node. We have proved that maximizing the minimum energy conservation is an NP-hard problem theoretically. Thus, a polynomial time algorithm has been proposed to derive the near-optimal performance. Extensive simulation results show that our proposed routing scheme outperforms previous works in terms of energy conservation and balanced distribution.

• Journal of the Korea Society of Computer and Information
• /
• v.19 no.9
• /
• pp.55-63
• /
• 2014

Up to date, numerous studies on wireless sensor networks have been performed to overcome the Energy-Constraint of the sensor system. Existing schemes for estimating the residual energy have considered only voltage of sensor system. However battery performance in the real is affected by temperature and load. In this paper we introduce more accurate scheme, for the use in wireless sensor node, based on the interpolation of lookup tables which allow for temperature and load characteristics, as well as battery voltage.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.17 no.1
• /
• pp.159-165
• /
• 2017

As increasing the number of the elderly people, various IT-based home systems for the elderly are actively studied. However, while most systems for the elderly focus on systems detecting emergency cases, systems considering energy reduction in the elderly housing are rarely found. In fact, the systems for the elderly housing consumes rather more electric power for their functions. In this paper, a emergency monitoring system including the functions to reduce energy useage is studied and it is implemented. Though the system, we can achieve both of future-oriented functions for the aged and green society, which are emergency monitoring and energy reduction.

• Journal of the Korean Institute of Educational Facilities
• /
• v.19 no.1
• /
• pp.45-53
• /
• 2012

Recently, as the environment issue has been stand out, people's interests in energy consumption of the building have been increased as well. Especially, university has been classified as the one of the main causes of excessive energy consumption. Therefore, domestic and foreign universities are trying to build a green campus in an attempt for sustainable development. Since early 2000s, foreign universities have been aware that one of the main causes of global warming is an excessive consumption of energy in universities. Accordingly, they adopted various energy management programs for the conservation. Ultimately, enforcing energy conservation and using alternative energy resulted in lower expense and it was a great help for the universities. On the other hand, excessive consumption of energy in domestic universities has been considered as serious, which led them to become the second main energy consumers in 2010. However, it seems people do not truly recognize the impotance of energy management, therefore, relatively little attention has been paid to this matter. Based on Leadership in Energy & Environmental Design(LEED) rating systems for on-campus building operation and maintenance, this research suggests the evaluation standard to effectively analyze the energy management activity with the best practices conducted in foreign universities and to solve the problem of campus facilities management in domestic universities. The result shows that domestic universities do not have a designated task force for effective energy management and the lack of energy professionals hinders for the long term development. Therefore, domestic universities should recognize the seriousness of the excessive energy consumption and develop low carbon green campus through proactive management practices since this is very essential for domestic universities to get more competitive in this global era.

• Journal of KIISE:Computing Practices and Letters
• /
• v.14 no.1
• /
• pp.13-21
• /
• 2008

In general, data communication among sensor nodes requires more energy than internal processing or sensing activities. In this paper, we propose a noble technique to reduce the number of packet transmissions necessary for sending/receiving queries/results among neighboring nodes with the help of context-aware routing tables. The important information maintained in the context-aware routing table is which physical properties can be measured by descendent nodes reachable from the current node. Based on the information, the node is able to eliminate unnecessary packet transmission by filtering out the child nodes for query dissemination or result relaying. The simulation results show that up to 80% of performance gains can be achieved with our technique.

• The Journal of the Korea Contents Association
• /
• v.7 no.1
• /
• pp.83-93
• /
• 2007

In this paper, we address a power-aware scheduling algorithm for a mixed real-time system which consists of periodic and sporadic tasks, each of which is characterized by its minimum period, worst-case execution requirement and deadline. We propose a dynamic voltage scaling algorithm called DVSMT(DVS for mixed tasks), which dynamically scales down the supplying voltage(and thus the frequency) using on-line distribution of the borrowed resources when jobs complete while still meeting their deadlines. With this scheme, we could reduce more energy consumption. As the proposed algorithm can be easily incorporated with RTOS(Real-Time Operating System), it is applicable for handhold devices and sensor network nodes that use a limited battery power. Simulation results show that DVSMT saves up 60% more than the existing algorithms both in the periodic-task and mixed-task systems.

• Journal of the Korea Society of Computer and Information
• /
• v.17 no.12
• /
• pp.137-148
• /
• 2012

In this paper, we proposed the location-aware coordinate routing algorithm for improving the performance of routing algorithm by using ZigBee in Smart Grid environment. A distributed address allocation scheme used an existing algorithm that has wasted in address space. The x, y and z coordinate axes from divided address space of 16 bit to solve this problems. However, coordinate routing does not take account of wireless link condition. If wiress link condition is not considered, when the routing table is updated, the nodes with bad link conditions are updated in the routing table and can be chosen as the next hop. This brings out the retransmissions because of received packet's errors. Also, because of these retransmissions, additional power is consumed. In this paper, we propose the location-aware coordinate routing algorithm considering wiress link condition, where reliable data transmission is made and the consumed enegy is minimize. and we compared and connected region and transition region of ZigBee location based routing in the aspect of average number of multi hops, subordinate packet delivery ratio, delay time, and energy consumption of proposed algorithm. It turned out that there were improvements in performances of each items.

• Journal of KIISE
• /
• v.42 no.12
• /
• pp.1495-1502
• /
• 2015

Data compression involves a trade-off between delay time and data size. Greater delay times require smaller data sizes and vice versa. There have been many studies performed in the field of wireless sensor networks on increasing network life cycle durations by reducing data size to minimize energy consumption; however, reductions in data size result in increases of delay time due to the added processing time required for data compression. Meanwhile, as energy generation occurs periodically in solar energy-based wireless sensor networks, redundant energy is often generated in amounts sufficient to run a node. In this study, this excess energy is used to reduce the delay time between nodes in a sensor network consisting of solar energy-based nodes. The energy threshold value is determined by a formula based on the residual energy and charging speed. Nodes with residual energy below the threshold transfer data compressed to reduce energy consumption, and nodes with residual energy above the threshold transfer data without compression to reduce the delay time between nodes. Simulation based performance verifications show that the technique proposed in this study exhibits optimal performance in terms of both energy and delay time compared with traditional methods.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.15 no.4
• /
• pp.993-999
• /
• 2011

In WSN, at the initial stage, sensor nodes are randomly deployed over the region of interest, and self-configure the clustered networks by grouping a bunch of sensor nodes and selecting a cluster header among them. Specially, in WSN environment, in which the administrator's intervention is restricted, the self-configuration capability is essential to establish a power-conservative WSN which provides broad sensing coverage and communication coverage. In this paper, we propose a communication coverage-aware cluster head election algorithm for Herearchical WSNs which consists of communication coverage-aware of the Base station is the cluster head node is elected and a clustering.