• Title/Summary/Keyword: Primary energy

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Advanced Energy Detector with Correlated Multiple Antennas

  • Kim, Sungtae;Lim, Sungmook
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.15 no.12
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    • pp.4600-4616
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    • 2021
  • In cognitive radio networks where unlicensed secondary users opportunistically access to licensed spectrum unused by licensed primary users, spectrum sensing is one of the key issues in order to effectively use the frequency resource. For enhancing the sensing performance in energy detection-based spectrum sensing, spatial diversity based on multiple antennas is utilized. However, the sensing performance can be degraded when antennas are spatially correlated, resulting in inducing the harmful interference to primary users. To overcome this problem, in this paper, an advanced energy detector is proposed. In the proposed sensing method, a weight matrix based on the eigenvalues of the spatial channels without any prior information on the primary signals is defined and utilized. In numerical simulations, it is shown that the proposed detector outperforms the conventional detector with regard to false-alarm and detection probabilities when antenna are spatially correlated.

Energy Consumption status of Apartment Buildings and Influence of Various Factors on Energy Consumption (공동주택의 에너지사용량 실태 분석 및 각종 인자가 에너지사용량에 미치는 영향 분석)

  • Kim, Yong-In;Song, Seung-Yeong
    • Journal of the Korean Solar Energy Society
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    • v.34 no.6
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    • pp.93-102
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    • 2014
  • The aim of this study is to analyze the influence of various factors on energy consumption of apartment buildings. Energy consumption data of the Green Together, integrated building energy management system maintained by the government were used, and end-use and primary energy consumption data of 2012 were analyzed for 181 apartment complexes completed between 2004 and 2011 in Seoul. Energy consumption by use, source and heating type were analyzed. Then, energy consumption trends were analyzed and suggested according to energy efficiency ratings, number of households, areas for exclusive use, number of floors, core types, building types, orientations and completion years.

Energy Detection Based Sensing for Secure Cognitive Spectrum Sharing in the Presence of Primary User Emulation Attack

  • Salem, Fatty M.;Ibrahim, Maged H.;Ibrahim, I.I.
    • IEIE Transactions on Smart Processing and Computing
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    • v.2 no.6
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    • pp.357-366
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    • 2013
  • Spectrum sensing, as a fundamental functionality of Cognitive Radio (CR), enables Secondary Users (SUs) to monitor the spectrum and detect spectrum holes that could be used. Recently, the security issues of Cognitive Radio Networks (CRNs) have attracted increasing research attention. As one of the attacks against CRNs, a Primary User Emulation (PUE) attack compromises the spectrum sensing of CR, where an attacker monopolizes the spectrum holes by impersonating the Primary User (PU) to prevent SUs from accessing the idle frequency bands. Energy detection is often used to sense the spectrum in CRNs, but the presence of PUE attack has not been considered. This study examined the effect of PUE attack on the performance of energy detection-based spectrum sensing technique. In the proposed protocol, the stationary helper nodes (HNs) are deployed in multiple stages and distributed over the coverage area of the PUs to deliver spectrum status information to the next stage of HNs and to SUs. On the other hand, the first stage of HNs is also responsible for inferring the existence of the PU based on the energy detection technique. In addition, this system provides the detection threshold under the constraints imposed on the probabilities of a miss detection and false alarm.

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Low Frequency Vibration Energy Harvester Using Stopper-Engaged Dynamic Magnifier for Increased Power and Wide Bandwidth

  • Halim, Miah Abdul;Kim, Dae Heum;Park, Jae Yeong
    • Journal of Electrical Engineering and Technology
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    • v.11 no.3
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    • pp.707-714
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    • 2016
  • We present a piezoelectric energy harvester with stopper-engaged dynamic magnifier which is capable of significantly increasing the operating bandwidth and the energy (power) harvested from a broad range of low frequency vibrations (<30 Hz). It uses a mass-loaded polymer beam (primary spring-mass system) that works as a dynamic magnifier for another mass-loaded piezoelectric beam (secondary spring-mass system) clamped on primary mass, constituting a two-degree-of-freedom (2-DOF) system. Use of polymer (polycarbonate) as the primary beam allows the harvester not only to respond to low frequency vibrations but also generates high impulsive force while the primary mass engages the base stopper. Upon excitation, the dynamic magnifier causes mechanical impact on the base stopper and transfers a secondary shock (in the form of impulsive force) to the energy harvesting element resulting in an increased strain in it and triggers nonlinear frequency up-conversion mechanism. Therefore, it generates almost four times larger average power and exhibits over 250% wider half-power bandwidth than those of its conventional 2-DOF counterpart (without stopper). Experimental results indicate that the proposed device is highly applicable to vibration energy harvesting in automobiles.

A Comparison of Decomposition Analyses for Primary and Final Energy Consumption of Korea (우리나라 1차 에너지와 최종 에너지 소비 변화요인 분해 비교분석)

  • Park, Sungjun;Kim, Jinsoo
    • Environmental and Resource Economics Review
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    • v.23 no.2
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    • pp.305-330
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    • 2014
  • There has been a lot of studies to identify the driving forces of energy consumption. Many of them decomposed the final energy consumption into the intensity effect, structural effect, and production effect. Those approach, however, could not consider the transformation loss during the electric power generation. Therefore, in this study, we conducted a decomposition analysis on the primary energy use basis to reflect that transformation loss. Log mean Divisia index and refined Laspeyres methods were used for the index decomposition. As results, we could find out that the difference between two approaches were definite. The intensity effect in 2011 is -0.607 times against 1981 in the final energy case, but -0.236 times in the primary energy case. The structure effect in 2011 is 0.227 times against 1981 in the final energy case, but 0.434 times in the primary energy case. Therefore, an analysis on the primary energy basis is essential when conducting a decomposition analysis.

A Study on Tendencies and Strategies to Develop Energy Technologies (에너지기술 개발동향 및 개발전략)

  • 박화춘;이동원;이장우
    • Proceedings of the Korea Technology Innovation Society Conference
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    • 1999.05a
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    • pp.395-408
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    • 1999
  • From the dependence the primary energy of about 97% on imported energy from abroad in Korea, 1997, and the pressure by international address to the Global Climate Change and environmental problem, we should do our best efforts to develop and diffuse of energy technologies. Also, the developed countries such USA, EU, Japan, and so on, are promoting and accelerating the development of energy technologies. From those point of views, we thought that Korea now in the time to provide the new and updated strategies to develop the energy technologies more actively for enhancing national capability, The Korea Institute of Energy Research(KIER), the complex research institution for energies except nuclear energy sponsored by government, prepared the mid and long term strategies and primary research projects, must be worked in and with the KIER, for the areas related to the energy conservation and efficiency increase, the energy environment, the alternative energy, and the diffusion of developed energy technologies.

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Energy Performance and Improvement in University Library - Concentrated on 'K'University Library located in Seojong City -

  • Roh, Ji Woong
    • KIEAE Journal
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    • v.14 no.4
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    • pp.47-52
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    • 2014
  • The problem of energy consumption is more serious in university buildings than primary, middle and high school buildings. Because university buildings have generally heating and cooling systems, and various incidental facilities. In university, the library is one of the building that many people use and the most energy is spent. So, investigation on energy saving is very important and urgent. This study aims finally to present the guideline for low-energy design of University library by aiding a designer to select best solution in the side of energy-saving. In this paper, composition of space, utilization schedule and performance of construction materials are grasped, some primary factors that effect to energy saving are analyzed by energy simulation. The result of this study is as follows; First, the subject library has more cooling load than heating load because of cooling load generated during middle season. Second, green roofs is the most effective to heating load saving, but not to cooling energy. Third, outdoor air cooling is the most effective to cooling energy saving among the investigated strategies included in this study.

Effect of Hydrogen Concentration on Surface Oxidation Behavior of Alloy 600 in Simulated Primary Water of Pressurized Water Reactor (원전 1차측 수화학 환경에서 수소 농도가 Alloy 600의 표면산화 거동에 미치는 영향)

  • Yun Soo, Lim;Dong Jin, Kim;Sung Woo, Kim;Seong Sik, Hwang;Hong Pyo, Kim;Sung Hwan, Cho
    • Corrosion Science and Technology
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    • v.21 no.6
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    • pp.466-475
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    • 2022
  • Surface oxides and intergranular (IG) oxidation phenomena in Alloy 600 depending on hydrogen concentration were characterized to obtain clear insight into the primary water stress corrosion cracking (PWSCC) behavior upon exposure to pressurized water reactor primary water. When hydrogen concentration was between 5 and 30 cm3 H2/kg H2O, NiFe2O4 and NiO type oxides were found on the surface. NiO type oxides were found inside the oxidized grain boundary when hydrogen concentration was 5 cm3 H2/kg H2O. However, only NiFe2O4 spinel on the surface and Ni enrichment were observed when hydrogen concentration was 30 cm3 H2/kg H2O. These results indicate that the oxidation/reduction reaction of Ni in Alloy 600 depending on hydrogen concentration can considerably affect surface oxidation behavior. It appears that the formation of NiO type oxides in a Ni oxidation state and Ni enrichment in a Ni reduction (or metallic) state are common in primary water. It is believed that the above different oxidation/reduction reactions of Ni in Alloy 600 depending on hydrogen concentration can also significantly affect the resistance to PWSCC of Alloy 600.

Comments on "Optimal Utilization of a Cognitive Shared Channel with a Rechargeable Primary Source Node"

  • El Shafie, Ahmed;Salem, Ahmed Sultan
    • Journal of Communications and Networks
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    • v.17 no.3
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    • pp.265-266
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    • 2015
  • In a recent paper [1], the authors investigated the maximum stable throughput region of a network composed of a rechargeable primary user and a secondary user plugged to a reliable power supply. The authors studied the cases of an infinite and a finite energy queue at the primary transmitter. However, the results of the finite case are incorrect. We show that under the proposed energy queue model (a decoupled M/D/1 queueing system with Bernoulli arrivals and the consumption of one energy packet per time slot), the energy queue capacity does not affect the stability region of the network.

Comparison Study of Extensive Air Shower Simulations with COSMOS and CORSIKA

  • Roh, Soon-Young;Kim, Ji-Hee;Ryu, Dong-Su
    • The Bulletin of The Korean Astronomical Society
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    • v.36 no.1
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    • pp.70.2-70.2
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    • 2011
  • Ultra-high energy cosmic rays(UHECRs) refer cosmic rays with energy above 1018eV. UHECR experiments have employed air shower simulations to quantify the properties of cosmic rays. Using COSMOS and CORSIKA, we have produced a library of over 15000 thinned extensive air shower(EAS) simulations with the primary energies ranging from 1018.5eV to 1020eV and the zenith angle of primary cosmic ray particles from 0 to 45 for proton and iron primaries. We have compared the results from CORSIKA and COSMOS. The comparison has shown perceptible differences in the ground distributions, longitudinal distributions, Calorimetric energy, and Xmax distributions. We have also measured the detector response evaluated using GEANT4 simulations. Here, we discuss S(800), i.e. the signal at a distance of 800 m from the shower core, as the primary energy estimator and present the lateral distribution function(LDF) with S(800).

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