• Journal of Electrical Engineering and Technology
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• 제9권4호
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• pp.1182-1187
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• 2014

This paper proposes an energy management strategy and adaptive control for superconducting magnetic energy storage (SMES) in a distribution power system with a grid-connected photovoltaic (PV) farm. Application of the SMES system can decrease the output power fluctuations of PV system effectively. Also, it can control the real and reactive powers corresponding to the scheduled reference values with adequate converter capacity, which are required at a steady-state operating point. Therefore, the adaptive control strategy for SMES plays a key role in improving the system stability when the PV generation causes uncertain variations due to weather conditions. The performance of proposed energy management strategy and control method for the SMES is then evaluated with several case studies based on the PSCAD/EMTDC$^{(R)}$ simulation.

• 한국통신학회논문지
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• 제32권10A호
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• pp.1004-1014
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• 2007

In sensor networks, it is crucial to reliably and energy-efficiently deliver sensed information from each source to a sink node. Specifically, in mobile sink (user) applications, due to the sink mobility, a stationary dissemination path may no longer be effective. The path will have to be continuously reconfigured according to the current location of the sink. Moreover, the dynamic optimal path from each source to the sink is required in order to reduce end-to-end delay and additional energy wastage. In this paper, an Adaptive Reversal Optimal path Tree (AROT) protocol is proposed. Information delivery from each source to a mobile sink can be easily achieved along the AROT without additional control overhead, because the AROT proactively performs adaptive sink mobility management. In addition, the dynamic path is optimal in terms of hop counts and the AROT can maintain a robust tree structure by quickly recovering the partitioned tree with minimum packet transmission. Finally, the simulation results demonstrate that the AROT is a considerably energy-efficient and robust protocol.

• 한국항행학회논문지
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• 제11권4호
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• pp.423-429
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• 2007

무선 스마트카드는 빌딩 보안 어플리케이션에 주된 역할을 하고 있다. 본 연구는 사용자에게 보다 편리함을 주고 스마트카드 시스템의 성능 개선을 제안한다. 스마트카드는 카드 리더기에 삽입을 하지 않고 장치에서 수센티미터 떨어져도 접근이 허용된다. 적응형 변조와 오류 제어를 통해 전력소비를 제어하는 성능은 필요하다. 본 논문에서는 적응형 리드 솔로몬 코드 기반의 FEC와 링크에서 M계수를 변화시킨 M-FSK변조에 대하여 연구한다. 적응형 변조와 적응형 오류 정정은 다른 다양한 정적스키마와 에너지 효율을 비교한 결과 50% 이상 에너지를 저장한다.

• 디지털융복합연구
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• 제11권12호
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• pp.401-406
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• 2013

이동통신 시스템에 적용되는 적응변조방식의 변환은 주변 환경을 고려한 변환을 사용하므로, 변환 조건 및 이에 따른 전송량의 변화에 대한 관점에서 다루었으나, 이동통신 단말기와 같이 에너지 효율이 좋아야 하는 경우에는 이러한 적응방식이 성능을 낮게 할 경우가 발생한다. 따라서 전송효율만을 고려하던 기존방식에서 소비 에너지를 고려하고, 프레임 길이를 조절하여 사용하는 적응변조방식을 제어하는 최적화 방식을 제안한다.

• 디지털융복합연구
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• 제10권9호
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• pp.369-374
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• 2012

통신 시스템의 설계 전력 여유분을 이용하여 기존 시스템의 구성을 변경하지 않고 시스템의 전반적인 전송효율을 증진시킬 수 있는 적응변조방식의 변환은 주로 전송량에 대한 관점에서 다루었으나, 변조방식의 변환 시 소모되는 순간 에너지는 이동통신 단말과 같이 밧데리가 필요한 장치의 효율을 낮춘다. 따라서 전송효율만을 고려하던 기존방식에 순간 에너지소비의 관점을 도입하여 에너지 효율을 고려한 변환기법을 제안한다.

• ETRI Journal
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• 제33권3호
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• pp.407-414
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• 2011

In an effort to reduce energy consumption, research into adaptive power management in real-time systems has become widespread. In this paper, a novel dynamic voltage scaling scheme is proposed for multiprocessor systems. Based on the concept of the Nash bargaining solution, a processor's clock speed and supply voltage are dynamically adjusted to satisfy these conflicting performance metrics. In addition, the proposed algorithm is implemented to react adaptively to the current system conditions by using an adaptive online approach. Simulation results clearly indicate that the superior performance of the proposed scheme can strike the appropriate performance balance between contradictory requirements.

• 한국위성정보통신학회논문지
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• 제7권3호
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• pp.116-120
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• 2012

전 세계적으로 빌딩 에너지 세이빙에 대한 관심이 증가하고 있으며, BEMS(Building Energy Management System)을 효율적으로 운용하기 위한 IT 기술에 대한 연구를 지속적으로 진행하고 있다. 최근 LED 조명기술의 발전으로 LED를 제어하여 에너지 절감효과를 극대화 할 수 있으며 BEMS에 이러한 LED 조명 제어기술들이 개발되고 있다. 본 논문에서는 건물에 설치되어 있는 IP 카메라와 Adaptive GMM(Gaussian Mixture Model)을 이용하여 BEMS용 LED 조명제어에 대한 시스템을 제안하였다. 설계한 구조를 기반으로 빌딩의 영상을 실시간으로 모니터링하고, 동적 객체를 영상추적하며, 다수의 객체를 클러스터링하고 인체 이동을 감지하여 LED 조명을 제어하는 기능을 제안하고, 관련 Software 개발을 통해 구현가능성을 입증하였다.

• Smart Structures and Systems
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• 제14권4호
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• pp.617-641
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• 2014

The energy constraint is still a common issue for the practical application of wireless sensors, since they are usually powered by batteries which limit their lifetime. In this paper, a practical compound energy efficiency strategy is proposed and realized in the implementation of a real time wireless sensor platform. The platform is intended for wireless structural monitoring applications and consists of three parts, wireless sensing unit, base station and data acquisition and configuration software running in a computer within the Matlab environment. The high energy efficiency of the wireless sensor platform is achieved by a proposed adaptive radio transmission power control algorithm, and some straightforward methods, including adopting low power ICs and high efficient power management circuits, low duty cycle radio polling and switching off radio between two adjacent data packets' transmission. The adaptive transmission power control algorithm is based on the statistical average of the path loss estimations using a moving average filter. The algorithm is implemented in the wireless node and relies on the received signal strength feedback piggybacked in the ACK packet from the base station node to estimate the path loss. Therefore, it does not need any control packet overheads. Several experiments are carried out to investigate the link quality of radio channels, validate and evaluate the proposed adaptive transmission power control algorithm, including static and dynamic experiments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권3호
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• pp.1345-1362
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• 2019

Most active queue management algorithms manage network congestion based on the size of the queue but ignore the network environment which makes queue size change. It seriously affects the response speed of the algorithm. In this paper, a new AQM algorithm named CT-AQM (Change Trend-Adaptive Queue Management) is proposed. CT-AQM predicts the change trend of queue size in the soon future based on the change rate of queue size and the network environment, and optimizes its dropping function. Simulation results indicate that CT-AQM scheme has a significant improvement in loss-rate and throughput.

• 풍력에너지저널
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• 제14권1호
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• pp.44-51
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• 2023

Some controllers have been introduced in various studies to mitigate the negative effects of renewable sources. These have been modified to fit a formed solution in various ways. This paper deals with the voltage regulation of wind farms in voltage dip situations where communication failures occur. The aim is to discuss the modification of the online wind farm management system. To discuss modifications of the online wind farm management system, we focus on voltage regulation of wind farms when communication failures occur. The structure has been designed to respond to a voltage drop when the outer reference is absent due to communication errors. Since the loss reduction effect has been maintained in the designed case studies, it can be derived that the proposed method can respond to voltage drops, along with a used objective function.