• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.8A
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• pp.790-797
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• 2006

IEEE 802.16e specifies two different power saving modes(PSM). One is sleep mode and the other is idle mode. These modes are different in that whether a mobile node maintains its state information with the serving base station or not. This difference results in different efficiency in consuming battery power of a mobile terminal. Therefore, it becomes important to analyze the performance of each power saving mode considering the parameters affecting the power consumption. In this paper, we propose a performance modeling framework of sleep mode and idle mode in terms of power saving efficiency. The analytical results are verified by computer simulations that idle mode is superior to sleep mode in power consumption of mobile node.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.12
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• pp.5712-5728
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• 2017

Recently, there are many studies, that considering green wireless cellular networks, have taken the energy consumption of the base station (BS) into consideration. In this work, we first introduce an energy consumption model of multi-mode sharing BS powered by multiple energy sources including renewable energy, local storage and power grid. Then communication load requests of the BS are transformed to energy demand queues, and battery energy level and worst-case delay constraints are considered into the virtual queue to ensure the network QoS when our objective is to minimize the long term electricity cost of BSs. Lyapunov optimization method is applied to work out the optimization objective without knowing the future information of the communication load, real-time electricity market price and renewable energy availability. Finally, linear programming is used, and the corresponding energy efficient scheduling policy is obtained. The performance analysis of our proposed online algorithm based on real-world traces demonstrates that it can greatly reduce one day's electricity cost of individual BS.

• Journal of Power Electronics
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• v.11 no.4
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• pp.408-417
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• 2011

The plug-in hybrid electric vehicles (PHEVs) are specialized hybrid electric vehicles that have the potential to obtain enough energy for average daily commuting from batteries. The PHEV battery would be recharged from the power grid at home or at work and would thus allow for a reduction in the overall fuel consumption. This paper proposes an integrated power electronics interface for PHEVs, which consists of a novel Eight-Switch Inverter (ESI) and an interleaved DC/DC converter, in order to reduce the cost, the mass and the size of the power electronics unit (PEU) with high performance at any operating mode. In the proposed configuration, a novel Eight-Switch Inverter (ESI) is able to function as a bidirectional single-phase AC/DC battery charger/ vehicle to grid (V2G) and to transfer electrical energy between the DC-link (connected to the battery) and the electric traction system as DC/AC inverter. In addition, a bidirectional-interleaved DC/DC converter with dual-loop controller is proposed for interfacing the ESI to a low-voltage battery pack in order to minimize the ripple of the battery current and to improve the efficiency of the DC system with lower inductor size. To validate the performance of the proposed configuration, the indirect field-oriented control (IFOC) based on particle swarm optimization (PSO) is proposed to optimize the efficiency of the AC drive system in PHEVs. The maximum efficiency of the motor is obtained by the evaluation of optimal rotor flux at any operating point, where the PSO is applied to evaluate the optimal flux. Moreover, an improved AC/DC controller based Proportional-Resonant Control (PRC) is proposed in order to reduce the THD of the input current in charger/V2G modes. The proposed configuration is analyzed and its performance is validated using simulated results obtained in MATLAB/ SIMULINK. Furthermore, it is experimentally validated with results obtained from the prototypes that have been developed and built in the laboratory based on TMS320F2808 DSP.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.194-197
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• 2015

최근 사물인터넷(IoT)기술이 발달함에 따라 사물과 스마트폰 간의 블루투스 통신이 많아지고 있다. 이에 따라 스마트폰의 배터리 사용량이 증가하였고 또한 사물에 내장된 배터리의 사용량도 함께 증가하였다. 스마트폰의 경우 현재 상용화 중인 배터리 측정 어플리케이션을 이용하면 블루투스 통신으로 인한 배터리 소모량 측정이 가능하기 때문에 스마트폰 보다 배터리 총량이 적은 아두이노를 이용하고자 한다. 아두이노를 기반으로 하여 스마트폰과 블루투스 통신을 하였을 경우 통신 간격에 따라 아두이노의 배터리 소모 패턴을 측정하였다. 본 논문에서는 블루투스 통신 간격에 따라 배터리 소모가 어떻게 변하는지 보여주고, 비교하여 분석하였다.

• International Journal of Computer Science & Network Security
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• v.22 no.4
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• pp.358-366
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• 2022

Wireless sensor networks (WSN) are becoming widely used in collecting and sensing information in different fields such as in the medical area, smart phone industry and military environment. The main concern here is reducing the power consumption because it effects in the lifetime of wireless sensor during commutation because it may be work in some environment like sensor in the battlefields where is not easy to change the battery for a node and that may decrease the efficiency of that node and that may affect the network traffic may be interrupted because one or more nodes stop working. In this paper we implement, simulate, and investigate S-MAC protocol with mobility support and show the sequence of events the sender and receiver go through. We tested some parameters and their impacts of on the performance including System throughput, number of packets successfully delivered per second, packet delay, average packet delay before successful transmission.

• Journal of Internet Computing and Services
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• v.15 no.4
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• pp.1-8
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• 2014

In wireless body sensor system(WB-SNSs), unlike existing sensor network system, the size of device is small and amount of battery is considerably limited. And various channel environments can be made by link channel characteristic, human movements, sensor placements, transmission power control(TPC) algorithms and so on. In this paper, therefore we take diverse experiments with totally considerated environments to overcome these restrictions and to manage the energy efficiently and find the value of target received signal strength indicator(RSSI) based on diverse factors such as human movements, sensor placements, and TPC algorithms. And we conduct analysis in terms of energy consumption and packet delivery rate(PDR) based on the experimental results. Through these analysis, we compare and evaluate the efficiency according to setup values of Target RSSI and Target RSSI range suitable for wireless body sensor network system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3813-3820
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• 2014

Recently, with the increase in electrical consumption and the unbalanced power demand and supply, the power reserve rate is becoming smaller and the reliability of the power supply is deteriorating. Under this circumstance, a Battery Energy Storage System (BESS) is considered to be an essential countermeasure for demand side management. On the other hand, an economic evaluation is a critical issue for the introduction of a power system because the cost of BESS is quite high. Therefore, this paper presents economic evaluation method for utility use by considering the best mix method and successive approximation method, and an economic evaluation method for customer use by considering the peak shaving function based on the real time price. From a case study on a model power system and educational customer, it was confirmed that the proposed method is a practical tool for the economic analysis of BESS.

• Journal of Convergence Society for SMB
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• v.1 no.1
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• pp.55-65
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• 2011

Due to the rapid advance of IT technologies such as mobile communication, sensor network, wearable computer, and so on, the needs of embedded software has increased. In those domain areas, the development of low-power embedded software is one of critical issues to enhance servicability of the system because almost embedded system depends on battery-based power supply system. Therefore this paper identifies the factors that can reduce the power consumption in embedded software operation, and proposes the method that how to handle the factors in software development process. Even though the existing and general studies about power reduction has been performed with code-based analysis, this analysis approach can lead reworks when the requirement for power consumption was not met. Our proposed techniques will support the power reduction in embedded software development process whenever the code was not developed. Our proposed process for lop-power embedded software development can gives the high quality in power-related serviceability.

• Journal of Digital Convergence
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• v.11 no.7
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• pp.261-269
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• 2013

Ubiquitous healthcare is a recent technology and a new methodology of medical diagnosis and medical care. However, in order for u-Healthcare service to become a general technology, there are some technological barriers(mobility, minimization, battery consumption etc) to overcome. In this paper, we developed a spectrum analysis system for smart phones. The results showed that compared to other solutions, our's were not only small in size but also almost the same in performance(reproducibility comparison experiments, Spectrum, Calibration Curve and Prediction). Therefore, the proposed solution is expected to be widely used in u-Health area.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.6
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• pp.455-466
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• 2020

In this study, we built a thermal model for SNIPE 6U nano-satellite which has scientific mission for measuring science data in near Earth space environment and described thermal design based on the thermal model. And the validity of the thermal design was verified through the on-orbit thermal analysis. The thermal design was carried out mainly on the passive thermal control techniques such as surface finishes, insulators, and thermal conductors in consideration of the characteristics of the nano-satellite. However, the components with narrow operating temperature range and directly exposed to the orbital thermal environments, such as a battery and thrusters, are accomodated with heaters to satisfy the temperature requirements. On-orbit thermal analysis conditions are based on the basic orbital conditions of the satellite, and thermal analysis was performed for Normal mode, Launch & Early Orbit Phase (LEOP), Safehold mode, and Maneuver mode which are classified by the power consumption and the attitude of the satellite according to the mission scenario. The analysis results for each mode confirmed that every component satisfies the temperature requirement. In addition, the heater capacity and duty cycle of the battery and thruster were calculated through the analysis results of the Safehold mode.