• 제목/요약/키워드: Second-order analysis

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확률론적 파괴역학 및 Size Effect Law에 적용을 위한 다중 균열 구조물에서의 에너지 해방률의 고차 미분값 계산 (Computation of the Higher Order Derivatives of Energy Release Rates in a Multiply Cracked Structure for Probabilistic Fracture Mechanics and Size Effect Law)

  • 황찬규
    • 한국전산구조공학회논문집
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    • 제21권4호
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    • pp.391-399
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    • 2008
  • 본 논문에서는 다중 균열 구조물에서의 균열 진전에 따른 에너지 해방을 및 고차 미분값을 구할 수 있는 가상균열 진전법을 제시한다. 이 방법은 다중 균열 체계의 에너지 해방율과 고차 미분값이 단 한번의 해석으로 수행될 수 있는 장점이 있다. 예제에서 얻어진 해의 최대 오차는 에너지 해방율 0.2%, 일차 미분값 $2\sim3%$, 이차 미분값 $5\sim10%$이다 이 방법으로 구한 에너지 해방률의 미분값들은 파괴 확률을 구하거나, sire effect law에 적용될 수 있다.

2차효과를 고려한 강사장교의 개선된 좌굴해석 (An Improved Stability Design of Steel Cable-Stayed Bridges using Second-Order Effect)

  • 경용수;김남일;이준석;김문영
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 2006년도 정기 학술대회 논문집
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    • pp.993-1000
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    • 2006
  • Practical stability design method of main members of cable-stayed bridges is proposed and discussed through a design example. For this purpose, initial tensions of stay cables and axial forces of main members are firstly determined using initial shaping analysis of bridges under dead loads. And then the effective buckling length using system elastic/inelastic buckling analysis and bending moments considering $P-{\delta}-{\Delta}$ effect by second-order elastic analysis are calculated for main girder and pylon members subjected to both axial forces and moments, respectively. Particularly, load combinations of dead and live loads, in which maximum load effects due to live loads are obtained, are taken into account and effects of live loads on effective buckling lengths are investigated.

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사장교 주탑 형상에 따른 안정해석 (An Analysis on the Stability for Pylon Types of Cable-Stayed Bridge)

  • 임정열;윤영만;안주옥
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 2000년도 봄 학술발표회논문집
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    • pp.246-252
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    • 2000
  • The nonlinearity of a cable-stayed bridge results in the large displacement of main girder due to a long span, the large axial forces reduce the catenary action of cables and the flexural stiffness. Therefore, the static and dynamic behavior of pylon for a cable-stayed bridge plays an important role in determining its safety. This study was performed to find the behavior of pylon of cable-stayed bridge for the first-order analysis considering of axial load only and for the second-order analysis considering of lateral deflection due to axial load. The axial force and moment values of pylon were different from the results of the first-order analysis and second-order analysis according to pylon shape and cross beam stiffness when the pylon was subjected to earthquake and wind loads. In the second-order analysis, comparing the numerical values of the member forces for the dynamic analysis, types 3 and 4 (A type) were relatively more advantageons types than types 1 and 2 (H type). Considering the stability for pylon of cable-stayed bridge (whole structural system), types 3 and 4 (A type) with pre-buckling of girder were proper types than types 1 and 2 (H type) with buckling of pylon.

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Selection of Canonical Factors in Second Order Response Surface Models

  • Park, Sung H.;Seong K. Han
    • Journal of the Korean Statistical Society
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    • 제30권4호
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    • pp.585-595
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    • 2001
  • A second-order response surface model is often used to approximate the relationship between a response factor and a set of explanatory factors. In this article, we deal with canonical analysis in response surface models. For the interpretation of the geometry of second-order response surface model, standard errors and confidence intervals for the eigenvalues of the second-order coefficient matrix play an important role. If the confidence interval for some eigenvalue includes 0 or the estimate of some eigenvalue is very small (near to 0) with respect to other eigenvalues, then we are able to delete the corresponding canonical factor. We propose a formulation of criterion which can be used to select canonical factors. This criterion is based on the IMSE(=Integrated Mean Squared Error). As a result of this method, we may approximately write the canonical factors as a set of some important explanatory factors.

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압축과 휨을 동시에 받는 가교량 주요부재의 좌굴설계 (Buckling Design of Temporary Bridges Subjected to Both Bending and Compression)

  • 소병훈;경용수;방진환;김문영
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 2006년도 정기 학술대회 논문집
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    • pp.977-984
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    • 2006
  • Generally main girders and steel piers of temporary bridges form the steel rahmen structure. In this study, the rational stability design procedure for main members of temporary bridges is presented using 3D system buckling analysis and second-order elastic analysis. 2 types of temporary bridges, which are possible to be designed and fabricated in reality, are chosen and the buckling design for them is performed considering load combinations of dead and live loads, thermal load, and wind load. Effective buckling length of steel piers, effects of live loads on effective length of main members, transition of ~id buckling modes, and effects of second-order analysis are investigated through case study of 2 temporary bridges.

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맥동관냉동기의 2차속도와 온도 (Second-order velocity and temperature in pulse tube refrigerators)

  • 이호진;채왕병;정은수
    • 설비공학논문집
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    • 제9권2호
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    • pp.239-248
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    • 1997
  • Steady components and unsteady components of second-order velocity and temperature within pulse tube refrigerators were obtained. Second-order solutions were obtained from the first-order solutions of continuity, momentum and energy equations, assuming that the amplitude of the piston motion is small. The axial temperature gradient was considered in the analysis. The flow direction of the streaming was consistent with previous experimental observations. Effects of axial temperature gradient on secondary flow and second-order temperature were shown.

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Second-order Motion Characteristics of a Semi-submersible Platform in Waves

  • Hong, Sa-Young;Nam, Bo-Woo;Kim, Jin-Ha;Kim, Young-Shik;Hong, Seok-Won;Kim, Young-Soo
    • International Journal of Ocean System Engineering
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    • 제1권3호
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    • pp.155-164
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    • 2011
  • The second-order motion characteristics of a semi-submersible are investigated in regular waves. A higher-order boundary element method in a frequency domain and a finite element method in a time-domain were applied to the numerical analysis of the nonlinear hydrodynamic force and motion characteristics of semi-submersibles in view point of potential flow. Various aspects of nonlinear effects on the heave and roll of a semi-submersible were numerically investigated and some selected cases were compared with the model test data.

시간영역에서 인장계류식 해양구조물의 비선형 운동응답 해석 (Analysis of the Nonlinear Motions of a Tension Leg Platform in Time Domain)

  • 이창호
    • 수산해양기술연구
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    • 제37권4호
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    • pp.313-320
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    • 2001
  • In the presence of incident waves with different frequencies, there are second order sum and difference frequency wane exciting forces due to the nonlinearty of the incident waves. Although the magnitudes of these nonlinear forces are small, they act at sum and difference frequencies away from those of the incident waves. So, the second order sum and difference frequency wane loads occurring close to the natural frequencies of TLPs often give greater contributions to high and low frequency resonant responses. The components of the second order forces which depend on first order quantities have been evaluated using the three dimensional source distribution method. The numerical results of time domain motion analysis for the nonlinear wave exciting forces in regular waves are compared with the numerical ones of frequency domain analysis. The results of comparison confirmed the validity of the proposed approach.

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하중증폭계수를 적용한 비대칭 비가새 골조 2차 해석 평가 (Evaluation of the Second Order Analysis of Asymmetric Unbraced Frame by using Load Amplification Factor)

  • 김희동
    • 한국강구조학회 논문집
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    • 제22권1호
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    • pp.87-97
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    • 2010
  • 본 연구는 비대칭 비가새 골조를 대상으로 강구조 설계기준에서 제시하고 있는 하중증폭계수를 적용한 2차 해석법의 타당성을 해석적 방법을 통해 평가하는데 그 목적이 있다. 이를 위해 KBC 2005에서 제안하고 있는 B1 및 B2 계수를 적용한 2차 해석과 KBC 2009에서 제안하고 있는 하중증폭계수를 적용한 직접해석을 5층 2스팬 및 5층 4스팬 비대칭 비가새 강구조 골조에 대해 실시하고, 그 해석 결과를 2차 비탄성 해석 결과와 비교하여 기준에서 제안된 2차 해석법들을 평가하였다. 해석의 주요 변수로는 골조 형상, 기둥 축력비, 해석방법, 기둥수평위치 등이 적용되었다. 연구 결과 구조물의 비대칭성은 B2 계수 및 제안된 해석법의 유효성에 영향을 미치는 것으로 나타났으며, 특히 기둥삭제 및 경사 기둥의 경우 오차의 범위가 증가하는 것으로 나타났다.

VM열펌프의 2차해석 (A Second-Order Analysis of VM Heat Pumps)

  • 최연석;정은수
    • 설비공학논문집
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    • 제8권2호
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    • pp.208-218
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    • 1996
  • Performance of a VM heat pump is considerably affected by various losses, such as enthalpy dump, reheat loss, pumping loss, conduction loss and shuttle loss. A second-order analysis model of VM heat pumps, which allows consideration of the major losses, was presented. Actual heat transfer rates for heat exchangers were calculated from the heat transfer rates obtained by the adiabatic analysis and various losses. New effective temperatures of heat exchangers were calculated from the actual heat transfer rates and the mean heat transfer coefficients until there was no appreciable change in the effective temperatures. Effects of design parameters, such as phase angle, swept volume ratio, regenerator length and speed on heating capacity, cooling capacity and COP were shown.

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