• 월간산업보건
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• s.361
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• pp.52-54
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• 2018

어딘가로 이동하는 방법 중 가장 느린 수단이 걷기다. 시간과 에너지를 소모해야 하지만, 사무실에 갇혔던 몸에 활기를 주고 바람과 공기를 있는 그대로 느낄 수 있으며 주변 환경을 돌아볼 수 있는 여유를 갖게 한다. 봄을 맞아 진행된 '건강걷기대회'에 대한산업보건협회 경인지역본부가 의료지원을 나섰다.

• 보일러설비
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• no.2 s.145
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• pp.108-111
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• 2006

몇해전부터 우리는 고유가라는 새로운 시대에 살면서도 고유가를 위한 합리적인 대안이 무엇인지에 대해 고민해보는 일은 매우 소홀하게 여기고 있다. 과연 인류최대의 현안인 환경문제와 에너지문제를 동시에 해결할 대체에너지는 없는지... 이러한 궁금증에 대해 관심을 갖는 이들은 매우적다. 우리는 태양열, 태양광발전, 바이오매스, 풍력, 소수력, 지열, 해양에너지, 폐기물에너지 8개분야의 신재생에너지중 풍력발전에 대해 알아보고 현재 국 · 내외에 설치돼 있는 풍력발전시스템에 대해 알아보고자 한다.

• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.6-10
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• 2015

RF energy harvesting technology is a promising technology for generating the electrical power from ambient RF signal to operate low-power consumption devices(eg. sensor) in wireless communication networks. This paper, motivated by this and building upon existing CR(Cognitive Radio) network model, proposes a optimal control policy for RF energy harvesting CR networks model where secondary users that have low power consumption harvest ambient RF energy from transmission by nearby active primary users, while periodically sensing and opportunistically accessing the licensed spectrum to the primary user's network. We consider that primary users and secondary users are distributed as Poisson point processes and contact with their intended receivers at fixed distances. Finally we can derive the optimal frame duration, transmission power and density of secondary user from the proposed model that can maximize the secondary users's throughput under the given several conditions and suggest future directions of research.

• The Journal of the Acoustical Society of Korea
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• v.22 no.2
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• pp.96-103
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• 2003

This paper describes a method for sinusoidal modeling of audio signals using perceptually weighted matching pursuit. Matching pursuits extracts iteratively the greatest energy signals from the input signals until the residual between the original and the reconstructed signal is zero. In this paper, perceptual matching pursuits using psychoacoustic model to matching pursuit extracts greatest perceived energy iteratively. To evaluate the performance of the perceptual matching pursuits it is compared with the sinusoidal matching pursuits which is not included perceptual weighting. For various audio signals the result of simulation shows that the perceptual matching pursuit is superior to the sinusoidal matching pursuits, especially for a high change rate in time domain it can synthesized original signal.

• Communications of the Korean Institute of Information Scientists and Engineers
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• v.30 no.7
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• pp.17-26
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• 2012

• KOREAN POULTRY JOURNAL
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• v.23 no.10 s.264
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• pp.124-127
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• 1991

지방은 물에는 녹지 않고 유기용매(에텔, 클로르포름, 벤젠 등)에 녹으며 다른 영양소에 비하여 탄소(C)와 수소(H)의 구성비가 높다. 따라서 모든 영양소 중에서 에너지의 함량이 가장 높아서 (탄수화물의 2.25배)동물체네 에너지 저장 수단이 된다. 지방으로 분류되는 물질 중에서 가장 중요한 것이 중성 지방(中性 脂肪, neutral fat 또는 triglyceride)이며 이밖에 wax, 인지질, 당지질, 지방 단백 및 각종 스테로이드 화합물 등이 지방에 포함된다.

• Journal of Broadcast Engineering
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• v.20 no.2
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• pp.215-223
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• 2015

Energy harvesting technique is an energy charging technique for communication device in energy-constrained environment. Recently, energy harvesting technique that harvests energy from wireless radio frequency signal is proposed. Representatively, there are time switching technique and power splitting technique. This paper proposes an optimal harvesting time allocation scheme in a wireless cognitive relay network when secondary user relay uses energy harvesting technique to transmit information. Secondary user relay receives information and energy simultaneously from the secondary user source's signal via time switching technique. We aim to maximize the instantaneous throughput by optimizing harvesting time of the secondary user relay. Simulation results show that using optimized harvesting time gets larger instantaneous throughput compared to using constant harvesting time.

• KIISE Transactions on Computing Practices
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• v.22 no.9
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• pp.467-472
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• 2016

In this study, we propose an Energy-Aware Web service to optimize energy efficiency using the characteristics of the system load. Currently, the service scale of data center is growing and the range of its applications is enlarged, causing interest in energy conservation. In particular, the web service has the largest proportion among various services of the data center. We propose a new energy saving method for web services guaranteeing the performance requirements of the services. The proposed method is optimized through the differences of energy-consumption rate over the system load. Performance evaluation has been performed under conditions similar to the actual service. The results indicated that the maximum energy reduction by the proposed method is up to 30% better than the existing methods.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.623-625
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• 2009

주택내에서 사용되고 있는 기존의 에너지 사용량 관리 시스템의 경우는 단순한 전기 에너지 관리 시스템이기 때문에 현재와 같이 에너지를 사용하는 가전 정보기기의 증가 및 사용자 요구사항을 반영하기에는 매우 미흡하였다. 또한 최근 에너지 고갈에 대한 우려로 인해 에너지 수급 불안 및 유가 급등 등으로 국가 경쟁력 확보 차원에서 주택 내 에너지 절감 기술에 대한 필요성이 함께 증가하고 있기 때문에 기존의 방식처럼 해당 기기를 통해 전력 사용량을 모니터링 하거나 단순 제어하는 방식에서 벗어나 거주자의 기능성과 편리성을 유지하면서 주택 내의 에너지를 효율적으로 절감하기 위한 지능적 제어 방법을 제안하고자 한다.

• Journal of KIISE
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• v.43 no.12
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• pp.1412-1419
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• 2016

In cognitive radio sensor networks (CRSNs), secondary users (SUs) can occupy licensed bands opportunistically without causing interferences to primary users (PUs). SUs perform spectrum sensing to detect the presence of PUs. Sensing time is a critical parameter for spectrum sensing that can yield a tradeoff between sensing performance and secondary throughput. In this study, we investigate new approaches for spectrum sensing by exploring the tradeoff from a) spectrum sensing for PU detection (SSPD) and b) spectrum sensing for secondary throughput (SSST). In the proposed scheme, the first sensing result of the current frame determines the dynamic performance of the second spectrum sensing. Energy constraint in CRSNs leads to maximized network energy efficiency via optimization of sensing time. Simulation results show that the proposed scheme of SSPD and SSST improves network performance in terms of energy efficiency and secondary throughput, respectively.