• 제목/요약/키워드: high-aspect-ratio

검색결과 948건 처리시간 0.032초

열에너지 저장용 암반 공동의 최적 종횡비 결정을 위한 역학적 안정성 해석 (Mechanical Stability Analysis to Determine the Optimum Aspect Ratio of Rock Caverns for Thermal Energy Storage)

  • 박도현;류동우;최병희;선우춘;한공창
    • 터널과지하공간
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    • 제23권2호
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    • pp.150-159
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    • 2013
  • 일반적으로 열저장소의 종횡비(폭에 대한 높이의 비)가 커짐에 따라 저장된 열에너지의 성층화가 높게 유지될 수 있는 것으로 알려져 있다. 따라서 열저장소의 열적 성능을 높이기 위해서는 저장소 종횡비를 크게 설정하는 것이 유리할 것이다. 그러나 종횡비의 증가에 따라 저장소의 폭에 비해 높이가 커지고, 이는 열저장소의 구조적 안정성 측면에서 불리하게 작용할 수 있으므로 저장소의 최적 종횡비 결정시 열적 성능 분석과 더불어 역학적 안정성에 대한 정량적인 분석이 수행되어야 할 것이다. 본 연구에서는 지하 열에너지 저장을 위한 사일로형 암반공동의 종횡비 변화에 따른 역학적 안정성을 수치해석적으로 조사하였다. 적용한 종횡비는 1-6의 범위이었고, 전단강도 감소기법에 의한 안전율을 토대로 암반공동의 역학적 안정성을 평가하였다. 종횡비별 안정성 분석 결과, 암반공동의 종횡비가 증가함에 따라 안전율이 감소하는 경향을 보였으며, 주변 암반의 측압계수가 안정성에 미치는 영향이 큰 것으로 분석되었다. 또한 동일한 암반특성 및 종횡비 조건에서 암반공동의 규모(저장 용량)가 줄어듦에 따라 안정성이 향상되는 것으로 나타나, 큰 규모의 단일 암반공동을 소규모의 다중 암반공동으로 분할함으로써 높은 종횡비의 암반공동 설계가 가능한 것을 알 수 있었다.

50μm급 마이크로렌즈 적용 2인치 휴대폰 LCD-BLU 금형 개발 : 광학패턴의 세장비 영향 (A Study on the Fabrication Method of Mold for 2 inch LCD-BLU by 50μm Microlens : Effect of Different Aspect Ratio)

  • 김종선;고영배;민인기;유재원;허영무;윤경환;황철진
    • 소성∙가공
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    • 제16권1호
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    • pp.48-53
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    • 2007
  • LCD-BLU(Liquid Crystal Display - Back Light Unit) consists of several optical sheets: LGP(Light Guiding Plate), light source and mold frame. The LGP of LCD-BLU is usually manufactured by etching process and forming numerous dots with $50{\mu}m$ in diameter on the surface. But the surface roughness of LGP with etched dots is very high, so there is much loss of light. In order to overcome the limit of current etched dot patterned LGP, optical pattern design with microlens of $50{\mu}m$ diameter was applied in the present study. The microlens pattern fabricated by modified LiGA with thermal reflow process was applied to the optical design of LGP and optical simulation was carried out to know tendency of microlens patterned LGP simultaneously. The attention was paid to the effects of different aspect ratio(i.e. $0.2\sim0.5$) of optical pattern conditions to the brightness distribution of BLU with microlens patterned LGP. Finally, high aspect ratio microlens patterned LGP showed superior results to the one made by low aspect ratio in average luminance.

고온 소결형 실리콘 태양 전지의 High Aspect Ratio 전극 형성이 가능한 Ag 페이스트의 레오로지 특성 연구 (A Study on Rheology Characteristics of Ag Paste for Screen Printing Method for Silicon Solar Cells Electrodes Capable of Forming High Aspect Ratio)

  • 오태현;김성빈;남수용
    • 한국인쇄학회지
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    • 제28권1호
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    • pp.15-24
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    • 2010
  • Photovoltaic solar cells are all in the incident because they are not converted into electrical energy, high-efficiency solar cells in order to reduce the loss of elements must be. Significant factor in the loss of solar cells, optical loss and electrical loss can be divided into. Optical losses occur when the sun will be joined on the surface of the reflection, the shadow loss due to electrodes, and the losses are in the solar wavelengths. Commercialization is currently the most common solar cells on the front of the light incident on the electrode is formed. Therefore, the shadow caused by the electrode to cover the dead area of the sun, due to factors that hinder the absorption of sunlight which is shadowing them and conversion efficiency of solar cells is the inhibition factor. These barriers to eliminate the electrode linewidth reduces the shadowing to reduce, but simply of the electrode line width is reduced electrode area by reducing the series resistance elevates this because to improve the electrode Aspect ratio(height/width) to increase Ag development of paste is required. In this study, aspect ratio of screen-printing method to increase the electrode Ag paste composition of the binder for the characterization of rheology in the shadow of the electrode by reducing the optical loss of the photoelectric conversion efficiency of solar cells to boost the performance measures was. Properties and printability of the paste, the binder resin sintered characteristics that affect the thermal properties are excellent with a good screen printability acrylic resin, ethyl cellulose, using a resin were evaluated. Prepared paste rheology properties, was formed to evaluate the electrode conductivity and aspect ratio.

Effect of steel fiber volume fraction and aspect ratio type on the mechanical properties of SIFCON-based HPFRCC

  • Kim, Seugnwon;Jung, Haekook;Kim, Yongjae;Park, Cheolwoo
    • Structural Engineering and Mechanics
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    • 제65권2호
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    • pp.163-171
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    • 2018
  • Plain concrete is a brittle material with a very low tensile strength compared to compressive strength and critical tensile strain. This study analyzed the dynamic characteristics of high-performance fiber-reinforced cementitious composites based on slurry-infiltrated fiber concrete (SIFCON-based HPFRCC), which maximizes the steel-fiber volume fraction and uses high-strength mortar to increase resistance to loads, such as explosion and impact, with a very short acting time. For major experimental variables, three levels of fiber aspect ratio and five levels of fiber volume fraction between 6.0% and 8.0% were considered, and the flexural strength and toughness characteristics were analyzed according to these variables. Furthermore, three levels of the aspect ratio of used steel fibers were considered. The highest flexural strength of 65.0 MPa was shown at the fiber aspect ratio of 80 and the fiber volume fraction of 7.0%, and the flexural strength and toughness increased proportionally to the fiber volume fraction. The test results according to fiber aspect ratio and fiber volume fraction revealed that after the initial crack, the load of the SIFCON-based HPFRCC continuously increased because of the high fiber volume fraction. In addition, sufficient residual strength was achieved after the maximum strength; this achievement will bring about positive effects on the brittle fracture of structures when an unexpected load, such as explosion or impact, is applied.

콘크리트의 형상비 및 온도변화에 따른 부착강도 특성평가 (Evaluation of Bond Strength Properties with Changing the Aspect Ratio and Temperature of Concrete)

  • 김현석;정원경;오한진;박준영;김형배
    • 한국도로학회논문집
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    • 제20권3호
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    • pp.19-26
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    • 2018
  • PURPOSES : The main purpose of this study is suggest of field bond strength evaluation method for more objective evaluation method through Evaluation of Bond Strength Properties with changing aspect ratio and temperature. METHODS : The evaluation is laboratory bond strength test. Using the core machine, the pull-off test method ; the bond strength test of interface layer the universal testing machine. RESULTS : As a result of the laboratory bond strength evaluation, it was verified that the bond strength by aspect ratio decreases linearly with increasing aspect ratio and the bond strength properties by temperature change existed at high and low temperature condition relative to odinary temperature condition. CONCLUSIONS : According to the results of laboratory bond strength evaluation, the field bond strength evaluation results suggest applying the proposed correction factor (0.8, 1.0, 1.4, 1.9) according to aspect ratio(0.5, 0.1, 1.5, 2.0), For more objective evaluation of the bond strength, it is analyzed that the evaluation value is within $6{\sim}32^{\circ}C$ and the result can be obtained within 5% of the coefficient of variation.

노즐 형상비에 따른 고압 분사류의 유동특성에 관한 실험적 연구 (Experimental Study on the Flow Characteristics of High Pressurized Jets Depending upon Aspect Ratio)

  • 남궁정환;이상진;김규철;이삼구;노병준
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2002년도 학술대회지
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    • pp.233-236
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    • 2002
  • The high-pressurized spray nozzle is used f3r special washing and cutting with strong impact force. The performance of this nozzle, which focused on spray penetration and radial dispersion, was mainly investigated to maximize the momentum and minimize the flow loss. Hence, our experimental research was conducted by changing the aspect ratio ranging from 0 to 3 with nozzle outlet of 1.1. The spray trajectory far high-pressurized water was experimentally investigated using PDPA diagnostics, which was available at spray downstream region. As the spray at upstream near the nozzle exit did not show the improved disintegration. The results showed empirical correlation with regard to non-dimensional axial velocity distribution, spray penetration, and radial spreading rate with photographic visualization.

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캐비티 내 고 점성유체의 비정상 흔합대류에 관한 수치해석적 연구 (Numerical Study of Unsteady Mixed Convection in a Cavity with High Viscous Fluid)

  • 배대석
    • 동력기계공학회지
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    • 제13권5호
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    • pp.11-17
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    • 2009
  • A numerical study of unsteady mixed convection in a cavity with high viscous fluid is presented. Finite volume method was employed for the discretization and PISO algorithm was used for calculating pressure term. The parameters governing the problem are the Rayleigh number ($10^3\;{\leq}\;Ra\;{\leq}\;10^5$), the Reynolds number (0 < Re $\leq$ 1), and the aspect ratio (0.5 $\leq$ AR $\leq$ 2). The fluid used is silicon oil, a high prandtl number fluid, Pr = 909.1. The results show velocity vectors and temperature distributions. It is found that the periodic flows in a cavity are observed at very low Reynolds numbers, and the period of periodic flow decreases with increasing Reynolds and Rayleigh numbers, and increases with increasing aspect ratio. Also, the Reynolds number range of periodic flow increases with increasing Rayleigh numbers and aspect ratio.

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Nonlinear Aeroelastic Analysis of a High-Aspect-Ratio Wing with Large Deflection Effects

  • Kim, Kyung-Seok;Lim, In-Gyu;Lee , In;Yoo, Jae-Han
    • International Journal of Aeronautical and Space Sciences
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    • 제7권1호
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    • pp.99-105
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    • 2006
  • In this study, nonlinear static and dynamic aeroelastic analyses for a high-aspect-ratio wing have been performed. To achieve these aims, the transonic small disturbance (TSD) theory for the aerodynamic analysis and the large deflection beam theory considering a geometrical nonlinearity for the structural analysis are applied, respectively. For the coupling between fluid and structure, the transformation of a displacement from the structural mesh to the aerodynamic grid is performed by a shape function which is used for the finite element and the inverse transformation of force by work equivalent load method. To validate the current method, the present analysis results of a high-aspect-ratio wing are compared with the experimental results. Static deformations in the vertical and torsional directions caused by an angle of attack and gravity loading are compared with experimental results. Also, static and dynamic aeroelastic characteristics are investigated. The comparisons of the flutter speed and frequency between a linear and nonlinear analysis are presented.

Experimental evaluation on the seismic performance of high strength thin-walled composite members accounting for sectional aspect ratio effect

  • Hsu, H.L.;Juang, J.L.;Luo, K.T.
    • Steel and Composite Structures
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    • 제9권4호
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    • pp.367-380
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    • 2009
  • This study focuses on the experimental evaluation of the flexural-torsional performance of high strength thin-walled composite members. A series of tests on composite members with various sectional aspect ratios subjected to eccentric cyclic loads were conducted. Test results show that the composite member's torsional strength could be approximated using a series of linear segments and evaluated using the superposition of the component steel and reinforced concrete responses. It is also validated from the tests that the strength deterioration of members subjected to combined loads is closely related to the aspect ratios of the sections. An interaction expression between the bending and torsion for high strength thin-walled composite members is proposed for engineering practice references.

강섬유 보강 폴리머 콘크리트의 강도특성 및 휨인성에 관한 연구 (Study on the Strength Characteristics and Flexural Toughness of Steel Fiber Reinforced Polymer Concrete)

  • 김기락;연규석;이윤수
    • 콘크리트학회논문집
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    • 제11권4호
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    • pp.137-145
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    • 1999
  • The use of steel fiber reinforced to improve the strength and flexural toughness of concrete is well known, but reinforcement of polymer concrete with steel fibers has been hardly reported till now. Polymer concrete has high strength, durability and freeze-thaw resistance than that of cement concrete, but it has disadvantage such as low flexural toughness. In this paper, the strength characteristics and flexural toughness of steel fiber reinforced polymer concrete are investigated experimentally with various steel fiber aspect ratios($\ell$/d), and contents(vol.%). As the result, the flexural and splitting tensile strengths and flexural toughness were increased aspect ratio, and reach the maximums at a aspect ratio of 50. The relationship between the compressive, flexural and splitting tensile strength were high. And the relationship between flexural strength and strain energy was approximately linear.