• Title/Summary/Keyword: tunnel layer

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Wind loads on a solar array

  • Kopp, G.A.;Surry, D.;Chen, K.
    • Wind and Structures
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    • v.5 no.5
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    • pp.393-406
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    • 2002

  • Aerodynamic pressures and forces were measured on a model of a solar panel containing six slender, parallel modules. Of particular importance to system design is the aerodynamically induced torque. The peak system torque was generally observed to occur at approach wind angles near the diagonals of the panel ($45^{\circ}$, $135^{\circ}$, $225^{\circ}$ and $315^{\circ}$) although large loads also occurred at $270^{\circ}$, where wind is in the plane of the panel, perpendicular to the individual modules. In this case, there was strong vortex shedding from the in-line modules, due to the observation that the module spacing was near the critical value for wake buffeting. The largest loads, however, occurred at a wind angle where there was limited vortex shedding ($330^{\circ}$). In this case, the bulk of the fluctuating torque came from turbulent velocity fluctuations, which acted in a quasi-steady sense, in the oncoming flow. A simple, quasi-steady, model for determining the peak system torque coefficient was developed.

  • https://doi.org/10.12989/was.2002.5.5.393 인용

Wind Tunnel Investigation of Fluctuating Pressure inside Building (풍하중에 의한 건물내부 압력의 동적변화에 관한 연구)

  • Kyoung-Hoon Rhee
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1990.10a
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    • pp.63-68
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    • 1990

  • The nature of fluctuating air pressure inside building was studied by testing a building model in a wind tunnel. The model has a single room and a sin81e window opening. Various opening conditions were tested in both laminar uniform wind and turbulent boundary-layer wind. The RMS and the spectra of the fluctuating internal pressure were measured. The test results support a recent theory which predicts the behavior of internal pressure under high wind based on aerodynamic analysis.

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Effect of Doubly Plasma Oxidation Time on TMR Devices (이중절연층 산화공정에서 플라즈마 산화시간에 따른 터널자기저항 효과)

  • Lee, Ki-Yung;Song, Oh-Sung
    • Journal of the Korean Magnetics Society
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    • v.12 no.4
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    • pp.127-131
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    • 2002

  • We fabricated MTJ devices that have doubly oxidized tunnel barrier using plasma oxidation method to from oxidized AlO$\sub$x/ tunnel barrier. Doubly oxidation I, which sputtered 10 ${\AA}$-bottom Al layer and oxidized it with oxidation time of 10 s. Subsequent sputtering of 13 ${\AA}$-Al was performed and the metallic layer was oxidized for 50, 80 and 120 s., respectively. Doubly oxidation II, which sputtered 10 ${\AA}$-bottom Al layer and oxidized it varying oxidation time for 30∼120 s. Subsequent sputtering of 13 ${\AA}$-Al was performed and the metallic layer was oxidized for 210 sec. Double oxidation process specimen showed MR ratio of above 27％ in all experiment range. Singly oxidation process. 13 ${\AA}$-Al layer and oxidized up to 210 s, showed less MR ratio and more narrow process window than those of doubly oxidation. Cross-sectional TEM images would that doubly oxidized barrowers were thinner and denser than singly oxidized ones. XPS characterization confirmed that doubly oxidation of Fe with bottom insulating layer. As a result, doubly oxidation could have superior MR ratio in process extent during long oxidation time because of preventing oxidation of bottom magnetic layer than singly oxidation.

  • https://doi.org/10.4283/JKMS.2002.12.4.127 인용 PDF KSCI

Development of a groundwater contamination potential evaluation technique by improving DRASTIC Index for a tunnel excavation area (개선된 DRASTIC 기법을 이용한 터널굴착 예정지역의 지하수 오염 가능성 평가기법 개발에 관한 연구)

  • Park, Jun-Kyung;Park, Young-Jin;Wye, Yong-Gon;Choi, Young-Tae;Lee, Han-Min
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.5 no.1
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    • pp.71-88
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    • 2003

  • The DRASTIC system is widely used for assessing regional groundwater pollution susceptibility by using hydrogeological factors such as depth to water, net recharge, aquifer media, soil media, topography, vadose zone media, hydraulic conductivity. This study is providing Modified Drastic Model to which lineament density, land use, influence of groundwater drawdown caused by tunnel excavation are added as additional factors using geographic information system, and then to evaluate groundwater contamination potential of ${\bigcirc}{\bigcirc}$ area. For statistical analysis, vector coverage per each factor is converted to grid layer and after each correlation coefficient between factors, covariance, variance, eigenvalue and eigenvector by principal component analysis of 3 direction, are calculated, correlation between factors is analyzed. Also after correlation coefficients between general DRASTIC layer and rated lineament density layer, between general DRASTIC layer and rated land use layer, between general DRASTIC layer and rated tunnel excavation influence layer are calculated, final modified DRASTIC model is constructed by using them with each weighting. When modified DRASTIC model was compared with general DRASTIC model, contamination potential in modified DRASTIC model is fairly detailed and consequently, vulnerable area which has high contamination potential could be presented concretly.

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