• Title/Summary/Keyword: Energy conversion efficiency

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Multi-Source Based Energy Harvesting Architecture for IoT and Wearable System (IoT 및 웨어러블 시스템을 위한 멀티 소스 기반 에너지 수확 구조)

  • Park, Hyun-Moon;Kwon, Jin-San;Kim, Byung-Soo;Kim, Dong-Sun
    • The Journal of the Korea institute of electronic communication sciences
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    • v.14 no.1
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    • pp.225-234
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    • 2019
  • By using the Triboelectric nanogenerators, known as TENG, we can take advantages of high conversion efficiency and continuous power output even with small vibrating energy sources. Nonlinear energy extraction techniques for Triboelectric vibration energy harvesting usually requires synchronized active electronic switches in most electronic interface circuits. This study presents a nonlinear energy harvesting with high energy conversion efficiency to harvest and save energies from human active motions. Moreover, the proposed design can harvest and store energy from sway motions around different directions on a horizontal plane efficiently. Finally, we conducted a comparative analysis of a multi-mode energy storage board developed by a silicon-based piezoelectricity and a transparent TENG cell. As a result, the experiment showed power generation of about 49.2mW/count from theses multi-fully harvesting source with provision of stable energy storages.

Studies on Variable Liquid-Column Oscillator for High Efficiency Floating Wave Energy Conversion System (가변 수주진동장치를 이용한 고효율 파력발전에 관한 연구)

  • Yang, Dong-Soon;Cho, Byung-Hak
    • Journal of Ocean Engineering and Technology
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    • v.23 no.5
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    • pp.15-24
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    • 2009
  • The results of a simulation study of variable liquid column oscillations in U-tanks with a novel control scheme are presented. The configuration under investigation is analogous to that of the tuned liquid-column damper used to suppress oscillatory motion in large structures like tall buildings and cargo ships. However, by virtue of an adequate controller, the response of amplitude of the U-tanks becomes larger in a desired frequency range. The motion of wave energy conversion system equipped with a variable liquid column oscillator is described by a series of nonlinear differential equations. The equations describe the motion of body under ocean wave excitation, and the motion of liquid with an air-spring effect caused by the compression and expansion of air in vertical liquid columns and air chambers. It is shown that the effect of the air-spring has a vital role to maintain the natural frequency of oscillation in the system to synchronize with the frequency of the ocean wave, thus the system provides the most effective mode for energy extraction from the ocean.

PV-Module's Voltage-Current special quality research by Electron-beam irradiation. (전자빔 조사에 의한 PV-Module의 전압-전류 특성)

  • Yoon Jeong-Phil;Lee Gi-Jae;Gang Byong-Bok;Cha In-Su;Gang Gi-Hwan;Jung Myung-Woong;Yu Gwon-Jong
    • Proceedings of the KIPE Conference
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    • 2001.07a
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    • pp.109-113
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    • 2001
  • Exhaustion and environmental problem are big problem of 21th century is flint energy and the importance of energy to alternate flint energy as being risen is embossed more. Photovoltaic system is occupying big flow along with wind force development among is many substitute energy has shortcoming that energy conversion efficiency falls behind than another thing substitute energy, This research investigates electron beam to specification energy to Module that was generalized and schematized difference of curved line after existing V-I efficiency characteristic curve and irradiation. And will analyze cause of Module's efficiency addition and subtraction by electron beam investigation.

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Growth Rate and Yield of a Methanotrophic Bacterium Methylosinus Trichosporium OB3b : I. Experimental Measurements (메탄자화균 Methylosinus trichosporium OB3b의 성장 속도와 수율 : I. 실험적 고찰)

  • 황재웅;송효학;박성훈
    • KSBB Journal
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    • v.13 no.4
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    • pp.391-398
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    • 1998
  • The effect of culture medium copper availability on the specific growth rate(${\mu}$) and carbon conversion efficiency (CCE) was sutided for an obligatory methanotroph Methylosinus trichosporium OB3b under various combinations of carbon and nitrogen sources. Methane or methanol was used as a carbon source, and nitrate or ammonium was used as a nitrogen source. Medium copper availability determined the intracellular location or kind of methane monooxygenase (MMO), cell-membrane (particulate or pMMO) when copper was present and cytoplasm (soluble or sMMO) when copper was deficient. When methane was used as a carbon source, copper-containing medium exhibited higher ${\mu}$ and CCE than copper-free medium regardless of the kind of nitrogen source. When methanol was used as a carbon source, however, the effect of copper disappeared. Ammonium gave the higher ${\mu}$ and CCE than nitrate for both methane and methanol. Those observation suggest that there exist an important difference in energy utilization efficiency for methane assimilation between sMMO and pMMO.

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Effect of the Linkers Between 9,9-Dimethylfluorenyl Terminal Moiety and a-Cyanoacrylic Acid Anchor on the $\lambda_{max}$ of the UV Spectrum and the Energy Efficiency in Dye-Sensitized Solar Cell (DSSC)

  • Lee, Min-U;Cha, Su-Bong;Lee, Jeong-Ryeol;Park, Se-Ung;Kim, Gyeong-Gon;Park, Nam-Gyu;Lee, Deok-Hyeong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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    • pp.316-316
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    • 2010
  • Six metal-free organic dyes having thiophene (1), benzene-thiophene (2), thiophene-benzene (3), thiophene-pyridine(4), thiophene-thiophene (5), and pyridine (6) linkers between 9,9-dimethylfluorenyl terminal group and $\alpha$-cyanoacrylic acid anchor were synthesized. Among them, organic dye 5 showed the longest ${\lambda}}max$ value (424 nm) in UV-Vis absorption spectrum, better incident monochromatic photon-to-current conversion efficiency (IPCE), highest short circuit photocurrent density (JSC, 9.33 mA2/cm2), and highest overall conversion efficiency ($\eta$, 3.91%).

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Properties of Blocking Layer with Ag Nano Powder in a Dye Sensitized Solar Cell

  • Noh, Yunyoung;Kim, Kwangbae;Choi, Minkyoung;Song, Ohsung
    • Journal of the Korean Ceramic Society
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    • v.53 no.1
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    • pp.105-109
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    • 2016
  • We prepared a working electrode (WE) with a blocking layer (BL) containing 0 ~ 0.5 wt% Ag nano powders to improve the energy conversion efficiency (ECE) of dye sensitized solar cell (DSSC). FESEM and micro-Raman were used to characterize the microstructure and phase. UV-VIS-NIR spectroscopy was employed to determine the adsorption of the WE with Ag nano powders. A solar simulator and a potentiostat were used to confirm the photovoltaic properties of the DSSC with Ag nano powders. From the results of the microstructural analysis, we confirmed that Ag nano powders with particle size of less than 150 nm were dispersed uniformly on the BL. Based on the phase and adsorption analysis, we identified the existence of Ag and found that the adsorption increased when the amount of Ag increased. The photovoltaic results show that the ECE became 4.80% with 0.3 wt%-Ag addition compared to 4.31% without Ag addition. This improvement was due to the increase of the localized surface plasmon resonance (LSPR) of the BL resulting from the addition of Ag. Our results imply that we might be able to improve the efficiency of a DSSC by proper addition of Ag nano powder to the BL.

Effect of Titanium Nanorods in the Photoelectrode on the Efficiency of Dye Sensitized Solar Cells

  • Rahman, Md. Mahbubur;Kim, Hyun-Yong;Jeon, Young-Deok;Jung, In-Soo;Noh, Kwang-Mo;Lee, Jae-Joon
    • Bulletin of the Korean Chemical Society
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    • v.34 no.9
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    • pp.2765-2768
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    • 2013
  • The effect of $TiO_2$ nanorods (TNR) and nanoparticles (TNP) composite photoelectrodes and the role of TNR to enhance the energy conversion efficiency in dye-sensitized solar cells (DSSCs) was investigated. The 5% TNR content into the TNP photoelectrode significantly increased the short-circuit current density ($J_{sc}$) and the open-circuit potential ($V_{oc}$) with the overall energy conversion efficiency enhancement of 13.6% compared to the pure TNP photoelectrode. From the photochemical and impedemetric analysis, the increased $J_{sc}$ and $V_{oc}$ for the 5% TNR/TNP composite photoelectrode was attributed to the scattering effect of TNR, reduced electron diffusion path and the suppression of charge recombination between the composite photoelectrode and electrolyte or dye.

Performance Analysis of Closed-type OTEC Cycle using Waste Heat (폐열 이용 폐쇄형 해양온도차발전 사이클의 성능)

  • Lee, Ho-Saeng;Jung, Dong-Ho;Hong, Seok-Won;Kim, Hyeon-Ju
    • Journal of Ocean Engineering and Technology
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    • v.25 no.1
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    • pp.80-84
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    • 2011
  • The cycle performance of closed ocean thermal energy conversion (OTEC) system with 50 kW gross power was evaluated to obtain the basic data for the optimal design of OTEC using waste heat such as solar power, discharged heat from condenser of power plant. The basic thermodynamic model for OTEC is Rankine cycle, and the surface seawater and deep seawater were used for the heat source of evaporator and condenser, respectively. The cycle performance such as efficiency, heat exchanger capacity, etc. was analyzed on the variation of temperature increase by waste heat. The cycle efficiency increased and necessary capacity of evaporator and condenser decreased under 50kW gross power with respect to the temperature increase of working fluid. Also, when the temperature increase is about $13.5^{\circ}C$, the heat which can be used is generated. By generator with 0.9 effectiveness under the simulated condition, the cycle efficiency was improved approximately 3.0% comparing with the basic cycle.

Performance Characteristics of OTEC(Ocean Thermal Energy Conversion) Power Cycle with Vapor-Liquid Ejector (증기-액 이젝터를 적용한 해양온도차발전 시스템의 성능 특성)

  • Yoon, Jung-In;Son, Chang-Hyo;Kim, Hyeon-Uk;Ha, Soo-Jung;Lee, Ho-Saeng;Kim, Hyun-Ju
    • Journal of Power System Engineering
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    • v.18 no.5
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    • pp.88-93
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    • 2014
  • In this paper, the performance analysis of condensation and evaporation capacity, turbine work and efficiency of the OTEC power system using vapor-liquid Ejector is presented to offer the basic design data for the operating parameters of the system. The working fluid used in this system is $CO_2$. The operating parameters considered in this study include the vapor quality at heat exchanger outlet, pressure ratio of ejector and inlet pressure of low turbine, mass flow ratio of separator at condenser outlet. The main results were summarized as follows. The efficiency of the OTEC power cycle has an enormous effect on the mass flow ratio of separator at condenser outlet. With a thorough grasp of these effects, it is possible to design the OTEC power cycle proposed in this study.

Microwave-assisted pretreatment technologies for the conversion of lignocellulosic biomass to sugars and ethanol: a review

  • Puligundla, Pradeep;Oh, Sang-Eun;Mok, Chulkyoon
    • Carbon letters
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    • v.17 no.1
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    • pp.1-10
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    • 2016
  • Lignocellulosic biomass conversion to biofuels such as ethanol and other value-added bio-products including activated carbons has attracted much attention. The development of an efficient, cost-effective, and eco-friendly pretreatment process is a major challenge in lignocellulosic biomass to biofuel conversion. Although several modern pretreatment technologies have been introduced, few promising technologies have been reported. Microwave irradiation or microwave-assisted methods (physical and chemical) for pretreatment (disintegration) of biomass have been gaining popularity over the last few years owing to their high heating efficiency, lower energy requirements, and easy operation. Acid and alkali pretreatments assisted by microwave heating meanwhile have been widely used for different types of lignocellulosic biomass conversion. Additional advantages of microwave-based pretreatments include faster treatment time, selective processing, instantaneous control, and acceleration of the reaction rate. The present review provides insights into the current research and advantages of using microwave-assisted pretreatment technologies for the conversion of lignocellulosic biomass to fermentable sugars in the process of cellulosic ethanol production.