• Title/Summary/Keyword: 점근해석

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Application of Saint-Venant's Principle to Anisotropic Beams (이방성 보 구조물 응력해석에서의 생브낭 원리)

  • Kim, Jun-Sik
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.4
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    • pp.451-455
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    • 2012
  • Asymptotic analysis is a powerful tool for the mathematically rigorous design and analysis of anisotropic beam structures. However, it has a limitation in that the asymptotic approach requires asymptotically correct boundary conditions for higher-order solutions, which are often needed for beams weak in shear. A method utilizing Saint-Venant's principle was proposed in a previous work to improve the stress state of isotropic beams and plates. In this paper, such a method is generalized for anisotropic beams, so that one does not need to consider the asymptotically correct boundary conditions for higher-order solutions. Consequently, solving the recursive system equations is not necessary, which makes the method very efficient in terms of accuracy and computational effort.

A Study of Transonic Premixed Combustion in a Diverging Channel Using Asymptotic Analysis (점근해석을 이용한 확대형 채널 내의 천음속 예혼합 연소에 관한 연구)

  • Lee, Jang-Chang
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.33 no.8
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    • pp.75-83
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    • 2005
  • A steady transonic dilute premixed combustion in a diverging channel is investigated by using asymptotic analysis. This model explores the nonlinear interactions between the near-sonic speed of the flow, the small changes in geometry from a straight channel, and the small heat release due to the one-step first-order Arrhenius chemical reaction. The reactive flow is described by a nonhomogeneous transonic small-disturbance (TSD) equation coupled with an ordinary differential equation for the calculation of the reactant mass fraction in the combustible gas. Also the asymptotic analysis reveals the similarity parameters that govern the reacting flow problem. The results show the complicated nonlinear interaction between the convection, reaction, and geometry effects and its effect on the flow behavior.

A Study of Transonic Combustion in a Diverging Channel Using Asymptotic Analysis (점근해석을 이용한 확대형 채널 내의 천음속 연소에 관한 연구)

  • Lee, Jang-Chang
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1604-1610
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    • 2004
  • A steady dilute premixed combustion at transonic speeds in a diverging channel is investigated. The model explores the nonlinear interactions between the near-sonic speed of the flow, the small changes in geometry from a straight channel, and the small heat release due to the one-step first-order Arrhenius chemical reaction. The reactive flow can be described by a nonhomogeneous transonic small-disturbance (TSD) equation coupled with an ordinary differencial equation for the calculation of the reactant mass fraction in the combustible gas. The asymptotic analysis results in the similarity parameters that govern the reacting flow problem. The model is used to study transonic combustion at various amounts of incoming, reactant mass, reaction rates, and channel geometries.

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Allowable limit of physical optics in radar cross section analysis of edge shape (가장자리 형상의 레이더 반사 면적 해석에서 물리광학기법의 적용 한계)

  • Baek, Sang-Min
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.46 no.1
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    • pp.78-85
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    • 2018
  • As a numerical analysis technique to predict the radar cross section of an aircraft, a full wave method or an asymptotic method is mainly used. The full-wave method is expected to be relatively accurate compared with the asymptotic method. The asymptotic method is numerically efficient, and it is more widely used in the RCS analysis. However, the error that occurs when estimating the RCS using the asymptotic method is difficult to predict easily. In this paper, we analyze the allowable limits of physical optics by constructing a wedge-cylinder model and comparing the RCS prediction results between the method of moment and physical optics while changing the edge shape. Finally, this study proposes a criterion for allowable limit of physical optics in the RCS estimation.

A Note on the Asymptotic Structure of the $90^{\circ}$-Corner Flow ($90^{\circ}$-모서리 유동의 점근적 구조에 관한 소효)

  • Suh, Yong-Kweon
    • Journal of Ocean Engineering and Technology
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    • v.2 no.2
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    • pp.46-50
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    • 1988
  • $90^{\circ}$-모서리 주위의 유동에 관한 수치해석결과를 바탕으로 그 유동구조를 점근적으로 해석하였다. 전체유동구조는 고전적 자유유선 이론에 의한 모델과 일치하였으며 경계층 박리점 주위의 유동구조는 최근의 트리플뎨 이론에 근거하였으며 그 결과가 수치해석의 결과와 아주 잘 맞는데 따른 결과이다.

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Numerical analysis of TSC of polyvinylidene flouride film by asymptotic estimation (점근 해법에 의한 PVDF 필름의 열자격 전류의 수치 해석)

  • 김기준;이준웅
    • Electrical & Electronic Materials
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    • v.5 no.2
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    • pp.166-174
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    • 1992
  • 본 논문에서는 열자격 전류 기법을 이용하여 폴리비닐덴 후로라이드필름에 대한 하전 입자의 거동 상황을 살펴보았는데 결과로 .betha.2, .betha.1, .alpha. 그리고 .alpha.'의 4개의 피크가 -35[.deg.C], -10[.deg.C], 60[.deg.C], 그리고 85[.deg.C]부근의 온도에서 관측되었다. 처음 .betha.2 피크와 .betha.1 피크에서의 온도는 항상 일정하였고 .alpha. 피크와 .alpha.'피크는 형성온도에 의존하였다. .betha.2 피크와 .betha.1 피크의 기원은 쌍극자의 기여로 .alpha. 피크는 결정질 영역의 얕게 트랩된 하전 입자의 탈트랩으로 그리고 .alpha.'피크는 형성온도에 따라 발생되는 Langmurian Model과 Henry Model에 의하여 나타났다. 이러한 해석을 위해 분리된 단일 완화곡선에 점근해법에 의한 수치해석 기법을 적용함으로서 사용시료의 제정수에 대한 계산을 보다 정확하게 구할수 있었으며 특히 적분항에 대한 계산오차가 감소함을 확인하였다.

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Uncertainty Assessment of Regional Frequency Analysis for Generalized Logistic Distribution (Generalized Logistic 분포형을 이용한 지역빈도해석의 불확실성 추정)

  • Shin, Hongjoon;Nam, Woosung;Jung, Younghun;Heo, Jun-Haeng
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.6B
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    • pp.723-729
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    • 2008
  • Confidence intervals of growth curves are calculated to assess the uncertainty of index flood method as a regional frequency analysis. The asymptotic variance of quantile estimator for the generalized logistic distribution is introduced to evaluate confidence intervals. In addition, the variances of at-site frequency estimator and regional frequency estimator are used to evaluate an efficiency index. The efficiency indexes for 14 homogeneous regions based on 378 stations show that index flood method estimators are more efficient than at-site frequency estimators. It is shown that the number of sites in a region needs to be limited for regional gain.

A Meched Asymptotic Analyis of Dust Particle Ignition (접합 점근법을 이용한 고체입자의 점화에 관한 연구)

  • 백승욱
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.10 no.4
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    • pp.471-476
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    • 1986
  • 본 연구에서는 구모양의 석탄가루나 곡식가루등 비금속성 고체입자가 압축파 (shock wave)에 의해 생성된 고온의 기체속에 놓여있을때 일어나는 점화현상을 활성 화에너지(activation energy)가 큰 경우의 접합 점근법을 이용 해석하였다. 이렇게 하여 얻어진 석탄입자에 대한 점화지연시간을 실험치와 비교 이의 타당성을 입증하였 다.

Asymptotic Properly Analysis on Digital Redesign to Linear Time-Invariant Systems (선형 시불변 시스템의 디지털 재설계 및 점근적 성질 해석)

  • Lee, Ho-Jae;Park, Jin-Bae;Lee, Yeon-Woo;Joo, Young-Hoon
    • Proceedings of the KIEE Conference
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    • 2004.07d
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    • pp.2251-2253
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    • 2004
  • 본 논문은 선형 행렬 부등식 기반의 디지털 재설계 기법의 점근적 성질을 논의한다. 이를 위하여 델타 작용소를 기반한 디지털 재설계 기법을 제안한다. 샘플링 주기의 감소에 따른 재설계된 디지털 제어기의 성능회복을 증명한다.

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