• 제목/요약/키워드: embedded foundation

검색결과 243건 처리시간 0.023초

비선형 지반특성이 수평 방향운동을 받는 기초지반체계의 동적강성에 미치는 영향 (Effects of Nonlinear Soil Characteristics on the Dynamic Stiffnesses of a Foundation-Soil System Excited with the Horizontal Motion)

  • 김용석
    • 한국지진공학회:학술대회논문집
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    • 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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    • pp.120-129
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    • 2000
  • As structure-soil interaction analysis for the seismic analysis of structures requires a nonlinear analysis of a structure-soil system considering the inelastic characteristics of soil layers nonlinear analyses of the foundation-soil system with the horizontal excitation were performed considering the nonlinear soil conditions for the nonlinear seismic analysis of structures. Stiff soil profile of SD and soft soil profile of SE specified in UBC were considered for the soil layers of a foundation and Ramberg-Osgood model was assumed for the nonlinear characteristics of soil layers. Studies on the changes of dynamci stiffnesses and damping rations of surface and embedded foundations depending on foundation size soil layer depth and piles were performed to investigate the effects of the nonlinear soil layer on the horizontal and rotational dynamic stiffnesses and damping ratios of the foundation-soil system According to the study results nonlinear prperties of a soil laryer decreeased horizontal and rotational linear stiffnesses and increased damping ratios largely Effects of foundation size soil layer depth and piles were also significant suggesting the necessity of nonlinear seismic analyses of structures.

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지반-기초-구조물 상호작용을 고려한 말뚝 기초 구조물에서의 지진 하중 평가 (Evaluation of Seismic Loading of Pile Foundation Structure Considering Soil-foundation-structure Interaction)

  • 유민택;하정곤;조성배;김동수
    • 한국지진공학회논문집
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    • 제18권3호
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    • pp.125-132
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    • 2014
  • In this study, a series of dynamic centrifuge tests were performed for a soil-foundation-structural interaction system in dry sand with various embedded depths and superstructure conditions. Sinusoidal wave, sweep wave and real earthquake were used as input motion with various input acceleration and frequencies. Based on the results, a natural period and an earthquake load for soil-structure interaction system were evaluated by comparing the free-field and foundation accelerations. The natural period of free field is longer than that of the soil-foundation-structure system. In addition, it is confirmed that the earthquake load for soil-foundation-structure system is smaller than that of free-field in short period region. In contrast, the earthquake load for soil-foundation-structure interaction system is larger than that of free-field in long period region. Therefore, the current seismic design method, applying seismic loading of free-field to foundation, could overly underestimate seismic load and cause unsafe design for long period structures, such as high-rise buildings.

대형풍력터빈 기초 인서트 설계에 관한 연구 (The study for design of the foundation insert of large wind turbine)

  • 한동영;최원호;이승구
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2007년도 춘계학술대회
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    • pp.391-394
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    • 2007
  • The foundation insert is a tubular steel section which is embedded into the concrete of the foundation. The tower base section of the wind turbine is mounted on it. It has a top flange (L type) protruding far enough above the concrete to allow bolts to be inserted from underneath. The load is transmitted to the concrete at the base of the section through a T shaped flange. It has many holes for the reinforcements and the cables. The reinforcements of the concrete foundation run through the insert via a series of holes to bind the inner section to the outer section. Holes are provided for the power and communications cabling. The design follows normal European wind turbine practice, based on GL 2003 and Eurocode regulations.

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Combination resonances of imperfect SSFG cylindrical shells rested on viscoelastic foundations

  • Foroutan, Kamran;Ahmadi, Habib
    • Structural Engineering and Mechanics
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    • 제75권1호
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    • pp.87-100
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    • 2020
  • The present paper investigates the combination resonance behavior of imperfect spiral stiffened functionally graded (SSFG) cylindrical shells with internal and external functionally graded stiffeners under two-term large amplitude excitations. The structure is embedded within a generalized nonlinear viscoelastic foundation, which is composed of a two-parameter Winkler-Pasternak foundation augmented by a Kelvin-Voigt viscoelastic model with a nonlinear cubic stiffness, to account for the vibration hardening/softening phenomena and damping considerations. With regard to classical plate theory of shells, von-Kármán equation and Hook law, the relations of stress-strain are derived for shell and stiffeners. The spiral stiffeners of the cylindrical shell are modeled according to the smeared stiffener technique. According to the Galerkin method, the discretized motion equation is obtained. The combination resonance is obtained by using the multiple scales method. Finally, the influences of the stiffeners angles, foundation type, the nonlinear elastic foundation coefficients, material distribution, and excitation amplitude on the system resonances are investigated comprehensively.

조명 조건에 강건한 스마트폰 카메라 맥박 측정을 위한 다이내믹 레인지 재구성 알고리즘 (Dynamic Range Reconstruction Algorithm for Smart Phone Camera Pulse Measurement Robust to Light Condition)

  • 박상욱;차경래
    • 대한임베디드공학회논문지
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    • 제10권1호
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    • pp.1-6
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    • 2015
  • Recently, handy pulse measurement method was introduced by using smart phone camera. However, measured values are not consistent with the variations of external light conditions, because the external light interfere with dynamic range of captured pulse image. Thus, adaptive dynamic range reconstruction algorithm is proposed to conduct pulse measurement robust to light condition. The minimum and maximum values for dynamic ranges of green and blue channels are adjusted to appropriate values for pulse measurement. In addition, sigmoid function based curve is applied to adjusted dynamic range. Experimental results show that the proposed algorithm conducts suitably dynamic range reconstruction of pulse image for the interference of external light sources.

의료기기 공용기술 활용 촉진을 위한 개방형 의료기기 플랫폼 개발 및 구현 (Development and Implementation of an open Medical Device Platform)

  • 김대관;홍주현;이효진
    • 대한임베디드공학회논문지
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    • 제16권6호
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    • pp.313-321
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    • 2021
  • The global market for medical devices is huge, and it will continue showing remarkable growth in the future. However, due to the entry barrier to develop medical devices, many domestic companies have technical problems in entering the medical device industry. In this paper, we introduce an open platform that can help with research and development for companies in the healthcare industry. This open platform consists of a hardware part and a software part. A hardware part is combined into CPU, base and other modules that are easy to replace and assemble. A software part is based on application software for development developed by Bionet. We test the performance of the open medical device platform using a biosignal processing algorithm.

Analytical solution for nonlocal buckling characteristics of higher-order inhomogeneous nanosize beams embedded in elastic medium

  • Ebrahimi, Farzad;Barati, Mohammad Reza
    • Advances in nano research
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    • 제4권3호
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    • pp.229-249
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    • 2016
  • In this paper, buckling characteristics of nonhomogeneous functionally graded (FG) nanobeams embedded on elastic foundations are investigated based on third order shear deformation (Reddy) without using shear correction factors. Third-order shear deformation beam theory accounts for shear deformation effects by a parabolic variation of all displacements through the thickness, and verifies the stress-free boundary conditions on the top and bottom surfaces of the FG nanobeam. A two parameters elastic foundation including the linear Winkler springs along with the Pasternak shear layer is in contact with beam in deformation, which acts in tension as well as in compression. The material properties of FG nanobeam are supposed to vary gradually along the thickness and are estimated through the power-law and Mori-Tanaka models. The small scale effect is taken into consideration based on nonlocal elasticity theory of Eringen. Nonlocal equations of motion are derived through Hamilton's principle and they are solved applying analytical solution. Comparison between results of the present work and those available in literature shows the accuracy of this method. The obtained results are presented for the buckling analysis of the FG nanobeams such as the effects of foundation parameters, gradient index, nonlocal parameter and slenderness ratio in detail.

실시간 운영체제 iRTOS에서의 CVM 네트워크 설계 및 구현 (Design and Implementation of Network in CVM on Real-Time Operation System, iRTOS)

  • 임재석;이철훈
    • 한국콘텐츠학회:학술대회논문집
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    • 한국콘텐츠학회 2008년도 춘계 종합학술대회 논문집
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    • pp.555-559
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    • 2008
  • 임베디드 시스템이 발전함에 따라 다양한 플랫폼을 가진 임베디드 디바이스에서 플랫폼 독립성을 위한 자바 기술이 급속도로 발전하고 있다. SUN 사의 CDC(Connected Device Configuration)에 정의된 CVM(Classic Virtual Machine)은 이러한 플랫폼 독립적인 자바 환경을 제공한다. 특히 셋톱박스나 스마트폰과 같은 임베디드 시스템에서는 네트워크 기능을 위해 CDC의 기본 프로파일인 FP(Foundation Profile)를 사용한다. 본 논문에서는 실시간 운영체제 iRTOS에서 네트워크 기능을 구현하기 위한 네트워크 API인 FP의 네이티브 메소드에 대해 설계 및 구현한 내용을 기술한다.

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Size dependent vibration of embedded functionally graded nanoplate in hygrothermal environment by Rayleigh-Ritz method

  • Singh, Piyush P.;Azam, Mohammad S.
    • Advances in nano research
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    • 제10권1호
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    • pp.25-42
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    • 2021
  • In this article, the vibration behavior of embedded Functionally Graded Nanoplate (FGNP) employing nonlocal Kirchhoff's plate theory has been investigated under hygrothermal environment. The FGNP is considered to be supported by Winkler-Pasternak foundation. The Eringen's differential theory is used for size effect on the vibration of the FGNP. Rayleigh-Ritz method with orthogonal polynomials are employed for the governing equations and edge constraints. The advantage of this method is that it overcomes all the drawbacks of edge constraints and can easily handle any combinations of mixed edge constraints. The coefficients viz. moisture expansion, thermal expansion and elastic coefficients are considered to be transversely graded across the FGNP. The similarity of the calculated natural frequencies is examined with the previous research, and a good concurrency is seen. The objective of this article is to analyze the parameters' effect on the nondimensionalized frequency of embedded FGNP under hygrothermal environment subjected to all possible edge constraints. For this, uniform and linear rise of temperature and moisture concentration are considered. The study highlights that the nonlocal effect is pronounced for higher modes. Moreover, the effect of the Pasternak modulus is seen to be prominent compared to the Winkler modulus on non dimensionalized frequencies of FGNP.

사질토지반에서 그룹 마이크로파일의 설치조건에 따른 인발거동특성 (Uplift Behavior of Group Micropile according to Embedded Pile Condition in Sand)

  • 경두현;김가람;박대성;김대홍;이준환
    • 한국지반공학회논문집
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    • 제31권2호
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    • pp.27-37
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    • 2015
  • 마이크로파일은 직경 300mm 이하의 소규모 말뚝기초형식으로, 기초구조물의 보강을 위해 널리 적용되고 있다. 본 연구에서는 일련의 인발재하시험을 통하여 그룹 마이크로파일의 설치조건에 대한 영향을 조사하였다. 본 연구를 위하여, 다양한 설치간격과 설치각도로 설치된 그룹 마이크로파일을 이용한 인발재하시험을 수행하였으며, 실험결과를 통해 인발지지력 증가특성과 인발변위 감소특성을 조사하였다. 인발저항력은 주로 마이크로파일의 설치각도에 영향을 받는 것으로 나타났으며, 인발저항력의 증가는 설치각도 15도, 30도, 45도에서 각각 33%, 59%, 5%가 증가되는 것으로 나타났다. 설치간격에 따른 인발변위의 감소량은 더 좁은 설치간격조건에서 크게 나타났으며, 동일한 설치간격조건에서의 설치각도에 따른 인발변위 저감율은 설치각도 15도, 30도, 45도에서 각각 50%, 53%, -45%가 되는 것으로 나타났다.