• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.860-863
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• 2010

Wireless sensor networks consist of small, autonomous devices with wireless networking capabilities. In order to further increase the applicability in real world applications, minimizing energy consumption is one of the most critical issues. Therefore, accurate energy model is required for the evaluation of wireless sensor networks. In this paper, we analyze the energy consumption for wireless sensor networks. To estimate the lifetime of sensor node, we have measured the energy characteristics of sensor node based on Telosb platforms running TinyOS. Based on the proposed model, the estimated lifetime of a battery powered sensor node can use about 6.925 months for 10 times motion detection per hour.

• Journal of KIISE:Information Networking
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• v.34 no.4
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• pp.262-268
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• 2007

The efficient node-energy utilization in wireless sensor networks has been studied because sensor nodes operate with limited power based on battery. To extend the lifetime of the wireless sensor networks, maintaining balanced power consumption between sensor nodes is more important than reducing total energy consumption of the overall network. Since a large number of sensor nodes are densely deployed and collect data by cooperation in wireless sensor network, keeping more sensor nodes alive as possible is important to extend the lifetime of the sensor network. In this paper, we submit an efficient energy aware routing protocol based on AODV ad hoc routing protocol for wireless sensor networks to increase its lifetime without degrading network performance. The proposed protocol is designed to avoid traffic congestion on minor specific nodes at data transfer and to make the node power consumption be widely distributed to increase the lifetime of the network. The performance of the proposed protocol has been examined and evaluated with the NS-2 simulator in terms of network lifetime and end-to-end delay.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.6
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• pp.1189-1194
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• 2005

An Ad-hoc network which do not use wired and base station system is composed the group of mobile and wireless nodes. That is various type of restriction. The biggest restriction is depend on the confined energy of battery. The network is devide more than two, if one of nodes consumed all energy that node can no longer participate to network. In recent years, the many number of studies research not only energy saving but also the networks lifetime extension which is to solve this problem. In this paper, we examine a AODV routing protocol which is modified to improve networks lifetime in mobile ad-hoc network. The one of improvement for AODV protocol is maximize the networks lifetime as apply Energy Mean Value algorithm which considerate node energy. We show the effectiveness for modified AODV(New-AODV) compared with AODV using NS-2(Network Simulator 2) the various performance metrics.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11A
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• pp.995-1003
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• 2005

Since the sensor network nodes have a small size and limited battery power, there have been many studies for reducing their energy consumption. Each sensor node can show different energy usage according to the frequency of event sensing and data transmission, and thus they have different lifetime. So, some nodes may run out of energy that causes disconnection of paths and reduction of network lifetime. In this paper, we propose a new energy-efficient routing algorithm for sensor networks that selects a least energy-consuming path among the paths formed by node with highest remaining energy and provides long network lifetime and somewhat uniform energy consumption by nodes. Simulation results show that our algorithm extends the network lifetime and enhances the network reliability by maintaining relatively uniform remaining energy distribution among sensor nodes.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.981-987
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• 2017

In this paper, we estimate the economic benefits of Energy Storage Systems (ESSs) for peak load shaving in an urban railway substation using the annual cost. The annual investment cost of ESSs is estimated using Net Present Value (NPV) and compared with the cost reduction of electricity by the ESS. The optimal capacities of the battery and Power Converting System (PCS) are determined for peak load shaving. The optimal capacity of the ESS and the peak load shaving is determined to maximize the profit by the ESS. The proposed method was applied to real load data in an urban railway substation, and the results show that electric power costs can be reduced. Other aspects of the ESS, such as the lifetime and unit price of the battery, are also investigated economically.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7A
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• pp.451-466
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• 2003

Untethered nodes in mobile ad-hoc networks strongly depend on the efficient use of their batteries. In this paper, we propose a new metric, the drain rate, to forecast the lifetime of nodes according to current traffic conditions. This metric is combined with the value of the remaining battery capacity to determine which nodes can be part of an active route. We describe new route selection mechanisms for MANET routing protocols, which we call the Minimum Drain Rate (MDR) and the Conditional Minimum Drain Rate (CMDR). MDR extends nodal battery life and the duration of paths, while CMDR also minimizes the total transmission power consumed per packet. Using the ns-2 simulator and the dynamic source routing (DSR) protocol, we compare MDR and CMDR against prior proposals for power-aware routing and show that using the drain rate for power-aware route selection offers superior performance results.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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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 ...

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.493-497
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• 2000

A battery is the device that transforms the chemical energy into the direct-current electrical energy without a mechanical process. Unit cells are connected in series to obtain the required voltage while being connected in parallel to organize capacity for load current. Because the voltage drop down in one set of battery is faster than in two one it may result in the low efficiency of power converter with the voltage drop and cause the system shutdown. However when the system being shutdown. However when the system being driven in parallel a circular-current can be generated,. It is shown that as a result the new batteries are heated by over-charge and over-discharge and the over charge current increases rust of the positive grid and consequently shortens the lifetime of the new batteries. The difference between the new batteries and old ones is the amount of internal resistance. In this paper we can detect the unbalance current using the microprocessor and achieve the balance current by adjusting resistance of each set, The internal resistance of each set becomes constant and the current of charge and discharge comes to be balanced by inserting the external resistance into the system and calculating the change of internal resistance.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.188.1-188.1
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• 2012

인공위성에 사용되는 배터리 기술은 1960년대 최초로 사용된 니켈 카드뮴(NiCd)을 시작으로 발전하기 시작해서 현재는 리튬-이온(Li-Ion)에 이르렀다. 리튬-이온 배터리는 높은 Energy Density(작은 크기와 무게), 낮은 자가 방전율을 가짐과 동시에 메모리 효과가 거의 없다는 장점이 있다. 하지만 리튬-이온 배터리 팩의 성능(Voltage, Capacity, Lifetime)은 사용된 Cell간 특성차이(State of Charge, Total Capacity Difference, Internal Impedance)에 의해 제한된다. 일반적으로 배터리는 원하는 전압과 용량을 확보하기 위해 직렬-병렬 혹은 병렬-직렬 구조를 가지는 팩 형태로 제작 된다. Cell간 특성차이가 존재하는 상태에서 배터리 팩을 사용할 경우 특정 Cell의 과충전 및 과방전이 발생하며 이로 인해 수명이 단축될 수 있고 심한 경우 폭발이 발생할 수 도 있다. 또한 Cell간 특성차이는 배터리팩의 사용가능 용량을 제한하는 효과를 가져 온다. 본 논문에서는 Battery 팩을 구성하는 Cell들에 특성 차이가 존재할 경우 발생할 수 있는 Battery 팩의 수명 단축 및 용량 감소 Mechanism에 대해서 고찰한다. 또한 Cell간 특성차이를 극복하기 위해 실제 위성 운용에 적용될 수 있는 배터리팩의 Balancing 방안과 함께 위성에 장착을 위해 보관중인 4p12s Battery의 Balancing 방안에 대해 고찰하고 Balancing 전후의 Cell간 특성(Voltage Dispersion) 차이 측정결과를 보인다. 이렇게 본 논문에서 소개한 리튬-이온 배터리의 전반적인 Balancing 방안은 추후 인공위성에 적용되는 리튬-이온 배터리의 운용 및 보관에 Guide Line을 제시할 것이라고 판단한다.

• Journal of Information Processing Systems
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• v.14 no.6
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• pp.1347-1360
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• 2018

Owing to limited energy in wireless devices power saving is very critical to prolong the lifetime of the networks. In this regard, we designed a cross-layer optimization mechanism based on power control in which source node broadcasts a Route Request Packet (RREQ) containing information such as node id, image size, end to end bit error rate (BER) and residual battery energy to its neighbor nodes to initiate a multimedia session. Each intermediate node appends its remaining battery energy, link gain, node id and average noise power to the RREQ packet. Upon receiving the RREQ packets, the sink node finds node disjoint paths and calculates the optimal power vectors for each disjoint path using cross layer optimization algorithm. Sink based cross-layer maximal minimal residual energy (MMRE) algorithm finds the number of image packets that can be sent on each path and sends the Route Reply Packet (RREP) to the source on each disjoint path which contains the information such as optimal power vector, remaining battery energy vector and number of packets that can be sent on the path by the source. Simulation results indicate that considerable energy saving can be accomplished with the proposed cross layer power control algorithm.