• 제목/요약/키워드: Single layer

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다층 TLD를 적용한 부유식 풍력 발전기 축소 모형의 운동에 대한 수치적 고찰 (Numerical Investigation on Motion of the Scale Model of a Floating Wind Turbine Using Multilayer TLDs)

  • 하민호;정철웅
    • 한국소음진동공학회논문집
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    • 제24권8호
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    • pp.621-627
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    • 2014
  • In this paper, a possibility of controlling the motion of a floating wind turbine with the tuned liquid damper(TLD) is numerically investigated. First, motion of the scale model of a floating wind turbine without the TLD is predicted and its results are compared to the measured data. There are reasonably good agreements between two results, which confirms validity of the present numerical methods. Then, the effect of TLD is quantitatively assessed by comparing the prediction results for the floating wind turbine with and without the TLD. It is shown that the motion of the scale model derived by external forces can be reduced by using the TLD. On a basis of this result, a multi-layer TLD is proposed to generate larger reaction force of the TLD at the fixed target frequency. The motions of the scale model with the multi-layer TLDs are computed and compared with that of the single-layer TLD. It is shown that the multi-layer TLD generate stronger reaction force and thus more reduce the motion of the floating body than the single-layer TLD.

EL-SEP: Improved L-SEP by adding Single-hop layer

  • LEE, WooSuk;Jung, Kye-Dong;Lee, Jong-Yong
    • International journal of advanced smart convergence
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    • 제6권1호
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    • pp.50-56
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    • 2017
  • Wireless sensor nodes have limited energy, so it is important to optimize energy consumption to preserve network lifetime. Various protocols have been proposed for this purpose. LEACH protocol and SEP are the representative protocols. These protocols become less effective as the Sensor Field becomes wider. To improve this, MR-SEP and L-SEP were proposed. These protocols increase the energy efficiency by dividing the Sensor Field into layers and reducing the transmission distance. However, when dividing a layer, there are cases where it is divided inefficiently, and a node within a certain range from a Base Station has a better transmission efficiency than a direct transmission method using a cluster method. In this paper, we propose a Single-hop layer for L-SEP to improve inefficient layer division and near node transmission efficiency. When the larger the Sensor Field, the better the performance of the proposed method by up to 87%. The larger the sensor field, the more efficient the proposed method is over the conventional method. That is, the proposed method is suitable for the wide Sensor Field.

회전하는 원통형밀폐용기내의 아랫면가열에 의한 이중확산대류에 관한 실험적 연구 (Double-Diffusive Convection Due to Heating from Below in a Rotating Cylindrical Cavity)

  • 강신형;이태홍;이진호
    • 대한기계학회논문집
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    • 제19권7호
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    • pp.1731-1740
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    • 1995
  • Experimental investigations have been made to study the double-diffusive nature of convection of an initially stratified salt-water solution due to heating from below in a rotating cylindrical cavity. The objective is to examine the flow phenomena and the heat transfer characteristics according to the changes in temperature gradient, concentration gradient and rotating velocity of cavity. Thermal and solutal boundary conditions at side wall are adiabatic and impermeable, respectively. The top and bottom plate are maintained each at constant temperature and concentration. The cavity is put into a state of solid body rotation. Like the stationary case, the types of initially-formed flow pattern are classified into three regimes depending on the effective Rayleigh number and Taylor number; stagnant flow regime, single mixed-layer flow regime and successively formed multi-mixed layer flow regime. At the same effective Rayleigh number, the number of initially-formed mixed layer and its growth rate decrease as the effect of rotation increases. The temperature and concentration profiles are both uniform in each layer due to convective mixing in the layered-flow regime, but look both liner in stagnant flow regime and single mixed-layer flow regime. At the interface between adjacent layers, the temperature changes smoothly but the concentration changes rapidly.

Ag 및 MgF2/AsGeSeS 다층박막에서의 편광 홀로그래피 회절효율 특성 (The Properties of Diffraction Efficiency in Polarization Holography using the Ag and MgF2/AsGeSeS Multi-layer)

  • 나선웅;여철호;정홍배;김종빈
    • 한국전기전자재료학회논문지
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    • 제15권12호
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    • pp.1070-1074
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    • 2002
  • We have carried out two-beam interference experiments to form holographic gratings on As$_{40}$ Se$_{15}$ S$_{35}$Ge$_{10}$ single layer, Ag/As$_{40}$ Se$_{15}$ S$_{35}$Ge$_{10}$ multi-layer. In this study, holographic gratings have been formed using He-Ne laser(632.8nm) under different polarization combinations(intensity polarization holography, phase polarization holography). The diffraction efficiency was obtained by the +lst order intensity. The maximum diffraction efficiency of As$_{40}$ Se$_{15}$ S$_{35}$Ge$_{10}$ single layer, As$_{40}$ Se$_{15}$ S$_{35}$Ge$_{10}$ and MgF$_2$/As$_{40}$ Se$_{15}$ S$_{35}$Ge$_{10}$ multi-layer were 0.8%, 1.4% and 3.1% under intensity polarization holography, respectively.

$CeO_2$/$BaTiO_3$이중완충막을 이용한 YBCO 박막 제작 (Fabrication of YBCO Superconducting Film with $CeO_2$/$BaTiO_3$Double Buffer Layer)

  • 김성민;이상렬
    • 한국전기전자재료학회논문지
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    • 제13권11호
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    • pp.959-962
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    • 2000
  • We have fabricated good quality superconducting YBa$_2$Cu$_3$$O_{7-x}$(YBCO) thin films on Hastelloy(Ni-Cr-Mo alloys) metallic substrates with CeO$_2$and BaTiO$_3$buffer layers in-situ by pulsed laser deposition in a multi-target processing chamber. YBCO film with CeO$_2$single buffer layer shows T$_{c}$ of 71.64 K and the grain size less than 0.1${\mu}{\textrm}{m}$. When BaTiO$_3$ is used as a single buffer layer, the grain size of YBCO is observed to be larger than that of YBCO/CeO$_2$by 200 times and the transition temperature of the film is enhanced to be about 84 K. CeO$_2$/BaTiO$_3$double buffer layer has been adopted to enhance the superconducting properties, which results in the enhancement of the critical temperature and the critical current density to be about 85 K and 8.4$\times$10$^4$ A/$\textrm{cm}^2$ at 77 K, respectively mainly due to the enlargement of the grain size of YBCO film.ilm.

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Time-Delay and Amplitude Modified BP Imaging Algorithm of Multiple Targets for UWB Through-the-Wall Radar Imaging

  • Zhang, Huamei;Li, Dongdong;Zhao, Jinlong;Wang, Haitao
    • Journal of Information Processing Systems
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    • 제13권4호
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    • pp.677-688
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    • 2017
  • In order to solve the undetected probability of multiple targets in ultra-wideband (UWB) through-the-wall radar imaging (TWRI), a time-delay and amplitude modified back projection (BP) algorithm is proposed. The refraction point is found by Fermat's principle in the presence of a wall, and the time-delay is correctly compensated. On this basis, transmission loss of the electromagnetic wave, the absorption loss of the refraction wave, and the diffusion loss of the spherical wave are analyzed in detail. Amplitude compensation is deduced and tested on a model with a single-layer wall. The simulating results by finite difference time domain (FDTD) show that it is effective in increasing the scattering intensity of the targets behind the wall. Compensation for the diffusion loss in the spherical wave also plays a main role. Additionally, the two-layer wall model is simulated. Then, the calculating time and the imaging quality are compared between a single-layer wall model and a two-layer wall model. The results illustrate the performance of the time-delay and amplitude-modified BP algorithm with multiple targets and multiple-layer walls of UWB TWRI.

DC, RF 마그네트론 코스퍼터링법으로 증착한 ZTO/GZO 투명전도성막의 열처리 조건이 박막의 물성에 미치는 영향 (Effect of Annealing on the Electrical Property and Water Permeability of ZTO/GZO Double-layered TCO Films Deposited by DC, RF Magnetron Co-sputtering)

  • 오성훈;강세원;이건환;정우석;송풍근
    • 한국표면공학회지
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    • 제45권3호
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    • pp.117-122
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    • 2012
  • ZTO/GZO double layered films were prepared on unheated non-alkali glass substrates. ZTO films were deposited by RF/DC hybrid magnetron co-sputtering using ZnO (RF) target and $SnO_2$ (DC) targets, and then GZO films were deposited by DC magnetron sputtering using an GZO ($Ga_2O_3$:5.57 wt%) target. These films were post-annealed at temperature of 200, $300^{\circ}C$ in air and vacuum ambient for 30 min. In the case of post-annealing in air, ZTO/GZO double layer showed relatively low resistivity change, compared to GZO single layer. Furthermore, ZTO/GZO double layer revealed low WVTR, compared to GZO single layer. Therefore, it can be confirmed that ZTO film doing a role with barrier for water or oxygen diffusion.

점토(粘土) 지반상(地盤上)의 성토(盛土)의 압밀침하(壓密沈下) 분석(分析) (Analysis for Consolidation-Settlement of Embankment on Clay Layers)

  • 정성관;권무남
    • Current Research on Agriculture and Life Sciences
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    • 제2권
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    • pp.98-108
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    • 1984
  • Generally, in case of constructing the embankments on the soft clay layers, one-dimensional consolidation settlement under the assumption of a middle position stress in a single layer makes a great difference with the integral value, ie. the final settlement. Consequently, to find how many equal segments of the soft clay layer are needed to converge into the integral value and which position should be taken as a position of mean stress, authors compared the theoretical value of the settlement due to one-dimensional consolidation with the practical value of the settlement due to two dimensional consolidation. The obtained results are as follows. 1) The practical value of the two-dimensional consolidation settlement can be estimated by the 74-83% theoretical value of the one-dimensional consolidation settlement. 2) When the soft clay layer was cut into 8-16 equal segments according to the depth, one-dimensional consolidation settlement converge into the integral value. 3) Assuming a total soft clay layer as a single one, the depth of a mean stress position is 0.29-0.37 of the thickness of the total soft clay layer. 4) The Hyperbola Method which presumes the long-term settlement from the short-term practical value of settlement is credible, because all practical value of the settlement are in safe side of the standard error of estimation and the correlation coefficient is up to 0.95.

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메쉬 구조의 Ag 나노박막을 이용한 ITO/Mesh-Ag/ITO 고전도성 투명전극 제조 및 특성 분석 (Fabrication of the ITO/Mesh-Ag/ITO Transparent Electrode using Ag Nano- Thin Layer with a Mesh Structure and Its Characterization)

  • 이동현;조의식;권상직
    • 반도체디스플레이기술학회지
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    • 제18권4호
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    • pp.100-104
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    • 2019
  • The 'ITO/Ag/ITO' multilayers as a highly conductive and transparent electrode, even with the optimum thickness conditions, the transmittances were much lower than those of a single ITO layer on some ranges of the visible wavelength. In order to improve the transmittance, Ag layer was formed with mesh structure. Where, the thickness of the Ag layer was about 10 nm and the space between the Ag lines was varied from 2.9 ㎛ to 19.6 ㎛ with the fixed Ag width of about 1.2 ㎛ in order to vary an open ratio of the Ag mesh structure. The transmittance and sheet resistance in the ITO/Mesh-Ag/ITO multilayer structure were analyzed depending on the open ratio. As a result, a trade off in the open ratio was necessary in order to obtain the transmittance as high as possible and the sheet resistance as possible low. By the open ratio of about 86%, in the ITO/Mesh-Ag/ITO multilayer structure, the transmittance was nearly same as the single ITO layer and the sheet resistance was about 62.3 Ω/.