• 제목/요약/키워드: power harvesting

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Electronic Theses and Dissertations' Development in University Libraries in Nigeria

  • Jerry Eyerinmene Friday;Constance Timi-pere Afamukoro
    • International Journal of Knowledge Content Development & Technology
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    • 제14권1호
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    • pp.75-110
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    • 2024
  • The study was meant to examine electronic theses and dissertations' development in Nigerian federal university libraries. The study adopted descriptive survey research design. The study population comprised forty-eight institutional repository librarians in eighteen Nigerian federal university libraries. The sample consisted of forty three librarians. A questionnaire was used for data collection. The data collected were analyzed with mean and standard deviation. Findings reveal that the policies available for developing electronic theses and dissertations (ETDs) in the libraries require submission of electronic copies of theses and dissertations by students, participation of digital/IR librarians in ETD development and provision of free access to ETDs; the libraries comply with standards of Open Archives Initiative Protocol for Metadata Harvesting and Search/Retrieval via URL using DSpace for building ETDs and taking advantage of such available ICT facilities as computers, scanners, CD-ROM, LAN, internet connectivity and printer. The libraries achieve ETD through digitisation, mandating submission of electronic versions of TDs by students and creation of IR. However, the process is hindered by technological obsolescence, financial problems, absence of clearly-defined ETD development policy, required ICT facilities and trained staff, copyright, irregular power supply and unstable internet connectivity. This study represents a fresh empirical investigation into electronic theses and dissertations' development in federal university libraries in Nigeria.

행거식 순환형 딸기 재배시스템 개발 (Development of Hanging Type Circular-patterned System for Strawberry Cultivation)

  • 안세웅;김동억;홍순중;강동현
    • 현장농수산연구지
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    • 제26권2호
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    • pp.25-30
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    • 2024
  • This study was conducted to develop the hanging type circular-patterned system that at maximizing the spatial efficiency of strawberry cultivation to increase yields, while also reducing labor and improving energy efficiency. The system consists of a cultivation bed units, longitudinal moving device, bed lifting device, front and rear transfer devices, lateral transfer device, nutrient supply device, and control unit. Performance testing revealed that the operational motor for longitudinal movement should have a torque of at least 0.1Nm based on the design weight and traction force of the cultivation bed unit. The power consumption required to move one cycle was calculated to be approximately 149Wh when performing harvesting or maintenance tasks for all 10 cultivation beds. Vibration angles measured during bed movement showed that the lateral transfer resulted in a roll angle ranging from -0.62° to 0.68° and a pitch angle ranging from -3.79° to 5.26°. For longitudinal transfer, the roll angle ranged from -3.37° to 3.36°, and the pitch angle ranged from -0.45° to 0.49°.

다공성 산화타이타늄 나노입자 합성과 염료감응형 태양전지 응용 (Synthesis of Mesoporous Titanium Dioxide Nanoparticles and Their Application into Dye Sensitized Solar Cells)

  • 김휘동;안지영;김수형
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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    • pp.64.2-64.2
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    • 2010
  • In order to improve the overall power conversion efficiency in dye-sensitized solar cells (DSSCs), it is very important to secure the sufficient surface area of photocatalytic nanoparticles layer for absorbing dye molecules. It is because increasing the amount of dye absorbed generally results in increasing the amount of light harvesting. In this work, we proposed a new method for increasing the specific surface area of photocatalytic titanium oxide ($TiO_2$) nanoparticles by using an inorganic templating method. Salt-$TiO_2$ composite nanoparticles were synthesized in this approach by spray pyrolyzing both the titanium butoxide and sodium chloride solution. After aqueous removal of salt from salt-$TiO_2$ composite nanoparticles, mesoporous $TiO_2$ nanoparticles with pore size of 2~50 nm were formed and then the specific surface area of resulting porous $TiO_2$ nanoparticle was measured by Brunauer-Emmett-Teller (BET) method. Generally, commercially available P-25 with the average primary size of ~25 nm $TiO_2$ nanoparticles was used as an active layer for dye-sensitized solarcells, and the specific surface area of P-25 was found to be ~50 $m^2/g$. On the other hand, the specific surface area of mesoporous $TiO_2$ nanoparticles prepared in this approach was found to be ~286 $m^2/g$, which is 5 times higher than that of P-25. The increased specific surface area of $TiO_2$ nanoparticles will absorb relatively more dye molecules, which can increase the short curcuit current (Jsc) in DSSCs. The influence of nanoporous structures of $TiO_2$ on the performance of DSSCs will be discussed in terms of the amount of dye molecules absorbed, the fill factor, the short circuit current, and the power conversion efficiency.

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Improved Power Conversion Efficiency of Dye-Sensitized Solar Cells Assisted with phosphor materials Scattering layer

  • Lee, Yong-Min;Choi, Hyun Ji;Kim, Dong In;Lee, Yul Hee;Yu, Jung-Hoon;Kim, Jee Yun;Seo, Hyeon Jin;Hwang, Ki-Hwan;Nam, Sang Hun;Boo, Jin-Hyo
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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    • pp.408.2-409
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    • 2016
  • Theoretically, the dye-sensitized solar cells (DSSCs) are high efficiency solar cells. However DSSCs have low power conversion efficiency (PCE) than silicon based solar cells. In this study, we use the phosphor materials, such as $Y_2O_3:Eu$ (Red), $Zn_2SiO_4:Mn$ (Green), $BaMgAl_{14}O_{23}:Eu$ (Blue), to enhance the PCE of DSSCs. Three phosphors were prepared and used as an effective scattering layer on the transparent $TiO_2$ with doctor blade method. We confirmed that the three scattering layers improve the PCE and Jsc due to the light harvesting enhancement via increased the scattering and absorbance in visible range. Under the sun illumination AM 1.5 conditions, the PCE of the mesoporous $TiO_2$ based DSSCs is 5.18 %. The PCE of the DSSCs with Y2O3:Eu, $Zn_2SiO_4:Mn$ and $BaMgAl_{14}O_{23}:Eu$ as scattering layer were enhanced to 5.66 %, 5.72% and 5.82%, respectably. In order to compare the optical properties change, DSSCs were measured by EQE, reflectance and PCE. At the same time, FE-SEM and XRD were used to confirm the structural changes of each layer.

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Optimization and improvement about DSSCs efficiency as thickness of TiO2 photoelectrode with Al back-reflector

  • 이용민;황기환;서현진;최현지;이율희;김동인;남상훈;부진효
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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    • pp.243.1-243.1
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    • 2015
  • To replace the based on silicon solar cells, the third generation solar cells, Dye-sensitized solar cells (DSSCs), is low fabrication than silicon solar cells, environmentally friendly and can be applied to various field. For this reason, the DSSCs have been continuously researched. But DSSCs have one drawback that is the low power conversion efficiency (PCE) than silicon solar cells. To solve the problem, we used the backr-eflector the Al foil that can be easily obtained from the surrounding in order to improve the efficiency of the DSSCs. Easily detachable Al foil back-reflector increases the photocurrent by enhancing the harvesting light because the discarded light is reused. It also leads to enhance the power conversion efficiency (PCE). In addition, we compared with the efficiency of the DSSCs that is applied and does not be applied with back-reflector according to the thickness of the TiO2 photoelectrode. When the back-reflector is applied to DSSCs, the photocurrent is increased. It leads to affect the efficiency. We used to solar simulator and Electrochemical Impedance Spectroscopy (EIS) to confirm the PCE and resistance. The DSSCs were also measured by External Quantum effect (EQE). At the same time, FE-SEM and XRD were used to confirm the thickness of layer and crystal structural of photoelectrode.

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3-D Hetero-Integration Technologies for Multifunctional Convergence Systems

  • 이강욱
    • 마이크로전자및패키징학회지
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    • 제22권2호
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    • pp.11-19
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    • 2015
  • Since CMOS device scaling has stalled, three-dimensional (3-D) integration allows extending Moore's law to ever high density, higher functionality, higher performance, and more diversed materials and devices to be integrated with lower cost. 3-D integration has many benefits such as increased multi-functionality, increased performance, increased data bandwidth, reduced power, small form factor, reduced packaging volume, because it vertically stacks multiple materials, technologies, and functional components such as processor, memory, sensors, logic, analog, and power ICs into one stacked chip. Anticipated applications start with memory, handheld devices, and high-performance computers and especially extend to multifunctional convengence systems such as cloud networking for internet of things, exascale computing for big data server, electrical vehicle system for future automotive, radioactivity safety system, energy harvesting system and, wireless implantable medical system by flexible heterogeneous integrations involving CMOS, MEMS, sensors and photonic circuits. However, heterogeneous integration of different functional devices has many technical challenges owing to various types of size, thickness, and substrate of different functional devices, because they were fabricated by different technologies. This paper describes new 3-D heterogeneous integration technologies of chip self-assembling stacking and 3-D heterogeneous opto-electronics integration, backside TSV fabrication developed by Tohoku University for multifunctional convergence systems. The paper introduce a high speed sensing, highly parallel processing image sensor system comprising a 3-D stacked image sensor with extremely fast signal sensing and processing speed and a 3-D stacked microprocessor with a self-test and self-repair function for autonomous driving assist fabricated by 3-D heterogeneous integration technologies.

인력대취검 개량제작시험연구 (A Study on the Improvement of Manual Rice Cutters)

  • 이철주
    • 한국농공학회지
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    • 제11권1호
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    • pp.1580-1597
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    • 1969
  • 1. The field test of our experiment comparing the traditional syckle and the new manually pulled cutter showed that the working efficiency of the manually pulled cutter is about two times higher than that of the syckle. The operator can standerect while using the manually pulled cutter, thus reducing fatigue. Because of the reduction in body fatigue, the operator is able to work more total hours, making the manually pulled harvester three times more efficient than the syckle. 2. The optimum angle for the V-shaped cutter blade varies according to the number of the hiller, but in manufacturing the cutter, the range must be controlled between $35^{\circ}{\sim}45^{\circ}$. 3. The radius of curvature of the V-shaped blade is closely related to the blade angle. The best results were obtained when the radii of curvature were r=32cm with $35^{\circ}$ angle, r=153mm with $45^{\circ}$ angle, and r=220mm with $40^{\circ}$ angle. 4. The hardness distribution test of the blade showed great differences between foreign made and domestic made blades. The heat treatment method must be greatly improved for superior hardness distribution. 5. Although the efficiency of the manually pushed cutter is equal to that of the manually pulled cutter, the manually pushed cutter is not only more expensive to produce but also has a much more complicated structure than the manually pulled cutter. Because of our rural economic conditions, the power harvester which is utilized in foreign countries can not yet be introduced here. Thus, the manually pulled cutter should be popularized in our rural areas until economic conditions will allow us to introduce power harvesters. 6. The use of the manually pulled cutter will make it possible for an operator to harvest an area in only one-third of the time that it would take to harvest the same area with a traditional syckle, and it will make it possible for an operator to earn about 8,000 won for harvesting 10 Jung-bo: such benefits will help in increasing farm income and will contribute to farm modernization.

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Solar-powered multi-scale sensor node on Imote2 platform for hybrid SHM in cable-stayed bridge

  • Ho, Duc-Duy;Lee, Po-Young;Nguyen, Khac-Duy;Hong, Dong-Soo;Lee, So-Young;Kim, Jeong-Tae;Shin, Sung-Woo;Yun, Chung-Bang;Shinozuka, Masanobu
    • Smart Structures and Systems
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    • 제9권2호
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    • pp.145-164
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    • 2012
  • In this paper, solar-powered, multi-scale, vibration-impedance sensor node on Imote2 platform is presented for hybrid structural health monitoring (SHM) in cable-stayed bridge. In order to achieve the objective, the following approaches are proposed. Firstly, vibration- and impedance-based hybrid SHM methods are briefly described. Secondly, the multi-scale vibration and impedance sensor node on Imote2-platform is presented on the design of hardware components and embedded software for vibration- and impedance-based SHM. In this approach, a solar-powered energy harvesting is implemented for autonomous operation of the smart sensor nodes. Finally, the feasibility and practicality of the smart sensor-based SHM system is evaluated on a full-scale cable-stayed bridge, Hwamyung Bridge in Korea. Successful level of wireless communication and solar-power supply for smart sensor nodes are verified. Also, vibration and impedance responses measured from the target bridge which experiences various weather conditions are examined for the robust long-term monitoring capability of the smart sensor system.

압전 캔틸레버 스프링 구조물(SPCS)의 에너지 하베스팅 특성 (Energy Harvesting Characteristics of Spring Supported Piezoelectric Cantilever Structure (SPCS))

  • 김경범;김창일;정영훈;이영진;조정호;백종후;남산;성태현
    • 한국전기전자재료학회논문지
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    • 제25권10호
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    • pp.766-772
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    • 2012
  • Spring supported piezoelectric cantilever structures (SPCS) were fabricated for vibration-based energy harvester application. We selected four elastic springs (A, B, C, and D type) as cantilever's supporter, each elastic spring has a different spring constant (S). The C type of SPCS ($S_C$: 4,649 N/m) showed a extremely low resonance frequency of 81 Hz along with the highest power output of 38.5 mW while the A type of SPCS ($S_A$: 40,629 N/m) didn't show a resonance frequency while. Therefore, it is considered that the lower spring constant lead to a lower resonance frequency of the SPCS. In addition, a tip mass (18 g) at one end of the SPCS could further reduce the resonance frequency without heavy degradation of power output.

주변 후방산란 통신에서의 채널 추정기법 (Method for Channel Estimation in Ambient Backscatter Communication)

  • 김수현;이동구;선영규;심이삭;황유민;신요안;김동인;김진영
    • 한국인터넷방송통신학회논문지
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    • 제19권4호
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    • pp.7-12
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    • 2019
  • 주변 후방산란 통신은 송신 전력효율 문제로 기존 RF통신에서 채널 추정방법인 파일럿(pilot) 신호를 통한 채널 추정기법이 제한된다. 제한된 송신 전력 환경에서 기존 주변 후방산란통신의 연구는 채널 상태로 인한 신호 변동을 고려하지 않은 이상적인 채널로 가정을 하고 연구되어 왔다. 본 논문은 주변 후방산란 통신 시스템에서 정규분포를 따르는 채널 상태인 주변 후방산란 통신 시스템에서 채널 추정 방법으로 블라인드 채널 추정기법 중 하나인 기댓값-최대화 알고리즘을 제안한다. 모의실험은 제안한 시스템 모델에서 기댓값-최대화 알고리즘과 추정값의 최소 분산을 나타내는 Bayesian Cramer-Rao 하한 경계를 이용하여 평균 제곱 오차(Mean Square Error, MSE)값이 하한 경계와 근접해 가는 것을 확인하고, 주변 후방산란 통신 시스템에서 채널 파라미터의 추정이 가능함을 증명한다.