• 제목/요약/키워드: Reuss

검색결과 24건 처리시간 0.024초

치밀골의 탄성 텐서 요소 경계 (The bounds for the elasticity tensor components of cortical bone)

  • 윤원석;윤영준
    • 한국정보전자통신기술학회논문지
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    • 제5권1호
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    • pp.52-59
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    • 2012
  • 뼈는 미네랄과 콜라겐으로 이루어진 복합 재료이고 횡방성 대칭의 역학적인 성질을 갖는다. 뼈의 유효 탄성 상수를 찾기 위해서는 복합재료역학에서 경계조건을 사용하여 그 값을 예측하고 있다. 그 방법들 중 하나인 보이트-로이스 경계조건은 근사값을 이용해서 유효 탄성 계수를 추정하는 방법이다. 기존의 방법은 고유값의 경계조건에 관한 경계조건을 보이지만, 이번 연구에서 우리는 수학적으로 이 경계조건이 각각의 탄성계수에 관해서 성립함을 보였다.

복합재료역학을 이용한 콜라겐 단백질 마이크로피브릴의 탄성율 예측 개선 (A Simpler Method to Estimate the Elastic Constant of Collagen-like Microfibril Using Voigt-Reuss Bounds)

  • 윤영준;배철수
    • 대한의용생체공학회:의공학회지
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    • 제31권3호
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    • pp.194-198
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    • 2010
  • The effective Young’s modulus of a microfibril surrounded by water may be simply calculated by using the upper (Voigt) and lower (Reuss) bounds, which is one way to estimate the Young’s modulus in composite materials. The Steered Molecular Dynamics (SMD) has been used for estimating the Young’s modulus of a microfibril surrounded by water. In this paper, the result estimated by the upper (Voigt) and lower (Reuss) bounds shows 9.2% to 21.8% discrepancy from the result estimated by SMD, but introducing “efficiency of reinforcement parameter” removes the discrepancy and shows good agreement with the result estimated by SMD. We found the best fit for the Young’s modulus against the size of the gap between microfibrils. Also the steps using these bounds are much simpler than SMD.

입자가 균일하게 분포된 복합체의 기계적 성질과 혼합률에 관한 수치적 연구 (A Numerical Investigation on the Rule of Mixtures for the Mechanical Properties of Composites with Homogeneously Distributed Particles)

  • 김형섭
    • 소성∙가공
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    • 제10권5호
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    • pp.396-401
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    • 2001
  • The concept of the mixtures can be used not only in the composites but also in the materials with precipitates and matrix. In this investigation, the finite element method of axisymmetric unit cell models and the rule of mixtures of the Voigt and the Reuss models are used to analyze the overall mechanical response of composites with homogeneously distributed particles. The calculations have been cameo out by taking the materials as i) hardening and ii) perfect plastic materials. The Plastic properties are predicted for various volume fractions of the soft and hard particles. The computational results are compared with the results of the rule of mixtures. It is found that the plastic flow curves agree well with the Voigt model when the volume fraction of the particles is high. On the other hand, the calculated flow curves exist between the Voigt model and the Reuss model when the volume fraction of the particles is low.

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The bounds for fully saturated porous material

  • Yoon, Young-June;Jung, Jae-Yong;Chung, Jae-Pil
    • 한국정보전자통신기술학회논문지
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    • 제13권5호
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    • pp.432-435
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    • 2020
  • The elasticity tensor for water may be employed to model the fully saturated porous material. Mostly water is assumed to be incompressible with a bulk modulus, however, the upper and lower bounds of off-diagonal components of the elasticity tensor of porous materials filled with water are violated when the bulk modulus is relatively high. In many cases, the generalized Hill inequality describes the general bounds of Voigt and Reuss for eigenvalues, but the bounds for the component of elasticity tensor are more realistic because the principal axis of eigenvalues of two phases, matrix and water, are not coincident. Thus in this paper, for anisotropic material containing pores filled with water, the bounds for the component of elasticity tensor are expressed by the rule of mixture and the upper and lower bounds of fully saturated porous materials are violated for low porosity and high bulk modulus of water.

Thirty new records of marine benthic Foraminifera from Korean waters

  • Lee, Somin;Frontalini, Fabrizio;Lee, Wonchoel
    • Journal of Species Research
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    • 제6권spc호
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    • pp.75-93
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    • 2017
  • As a part of a survey of indigenous biological resources of Korea, 30 marine benthic foraminiferal species belonging to 24 genera and seven orders (Astrorhizida, Lagenida, Lituolida, Miliolida, Robertinida, Rotaliida and Textulariida) were identified. Bottom sediment samples were collected from eight stations on the west and east coast of South Korea, in April 2015 and May 2016, respectively. Ten species belonging to nine genera and five orders (Lagenida, Lituolida, Robertinida, Rotaliida, Textulariida) were identified in the Yellow Sea. Among these taxa, Rotaliida was the dominant order, represented by four species: Evolvocassidulina tenuis (Phleger & Parker, 1951), Cibicides mabahethi Said, 1949, Cibicides pseudolabatulus Perelis & Reiss, 1975 and Cibicidoides barnetti Bermudez, 1949. Twenty species belonging to 15 genera and five orders (Astrorhizida, Lagenida, Lituolida, Miliolida, and Rotaliida) were identified from the East Sea and the Lagenida was the dominant order, represented by 11 species: Lagena strumosa Reuss, 1858, Lagena nebulosa (Cushman, 1923), Lagena striata var. semiornata Reuss, 1863, Procerolagena cylindrocostata Albani & Yassini, 1989, Fissurina bispinata $Ujii{\acute{e}}$, 1963, Oolina laevigata d'Orbigny, 1839, Polymorphina amplissima McCulloch, 1977, Polymorphina subelliptica McCulloch, 1977, Guttulina succincta McCulloch, 1977, Guttulina neoproblema McCulloch, 1977 and Lagenosolenia obtecta McCulloch, 1977. The findings described here increased the number of foraminiferal species in Korea to approximately 1060, and contribute to our understanding of the diversity of foraminifera in Korean waters.

부분분포하중이 평면 포물선아치의 동적응답에 마치는 영향 (Effects of Partially Distributed Loads on Dynamic Response of Plane Parabolic Arch)

  • 조진구;박근수
    • 한국농공학회논문집
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    • 제46권6호
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    • pp.21-28
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    • 2004
  • This study aims to investigate the effects of partially distributed loads on the dynamic behaviour of steel parabolic arches by using the elasto-plastic finite element model based on the Von Mises yield criteria and the Prandtl-Reuss How rule. For this purpose, the vertical and the radial load conditions were considered as a distributed loading and the loading range is varied from 40% to 100% of arch span. Normal arch and arch with initial deflection were studied. The initial deflection of arch was assumed by the sinusoidal motile of ${\omega}_i\;=\;{\\omega}_O$ sin ($n{\pi}x/L$). Several numerical examples were tested considering symmetric initial deflection when the maximum initial deflection at the apex is fixed as L/1000. The analysis resluts showed that the maximum deflection at the apex of arch was occurred when 70% of arch span was loaded. The maximum deflection at the quarter point of arch span was occurred when 50% of arch span was loaded. It is known that the optimal rise to span ratio between 0.2 and 0.3 when the vertical or radial distributed load is applied. It is verified that the influence of initial deflection of radial load case is more serious than that of vertical load case.

한국산 담수어류 피라미의 아기미에 기생하는 Myxobolus sp.에 관하여 (A report on the Myxobolus sp. (Myxosporea : Bivalvulida), found from the gills of the pale chub, Zacco platypus)

  • 지보영;김기홍;박수일
    • 한국어병학회지
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    • 제9권1호
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    • pp.15-19
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    • 1996
  • 피라미의 아가미로부터 검출된 Myxobolus sp.의 성숙 포자는 정면에서 특징적인 봉합융기가 없는 난형, 측면에서 직선적인 봉합면을 가진 레몬모양을 나타내었고 대칭적이며 표면이 평평한 포자각을 가졌다. 평균적인 포자의 길이, 넓이 및 두께는 각각 $10.4{\mu}m$, 7.7mm 및 $6.2{\mu}m$ 였고 평균적인 극낭의 길이와 넓이는 $4.6{\mu}m$$2.2{\mu}m$로 측정되었고 극낭속에 있는 극사는 6또는 7coil로 관찰되었으며 방출된 극사의 길이는 55-135㎛이었다. 한편으로 성숙 포자는 작은 극포간 돌기, 타원형의 요오드 친화성 공포 및 점막이 존재하는 것으로 관찰되었고 성숙 포자의 형태 및 크기는 M. cyprinicola Reuss, 1906과 가장 비슷한 것으로 나타났다.

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암석 물리 모델링: 기술 보고 및 적용 사례 (Rock Physics Modeling: Report and a Case Study)

  • 이광훈
    • 자원환경지질
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    • 제49권3호
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    • pp.225-242
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    • 2016
  • 암석 물리(rock physics)는 암석의 물성과 탄성파 자료의 정량적인 연결 고리로서 저류암 특성화와 모니터링 등에 적용되는 중요한 도구이다. 암석 물리를 기반으로 시추공 검층 자료로부터 공극 유체와 구성 성분이 다양한 암석의 성질을 대표하는 유효 탄성 계수(effective elastic constants)를 모델링하여 탄성파 자료에 적용함으로서 탄성파 자료전체에 대한 저류암 분포와 공극 유체를 유추할 수 있다. 본 보고에서는 먼저 Voigt, Reuss, Hashin-Shtrikman의 유효 탄성 계수 한계값과 Gassmann 방정식을 이용한 유체 치환에 대해서 설명한 후에 공극률이 비교적 높은 저류 사암에 널리 적용되는 접촉(contact) 암석 물리 모델들을 소개했다. 그리고 접촉 암석 물리 모델 중에서 분포 깊이가 어느 정도 일정하고 공극률이 비교적 높은 사암에 적합한 것으로 알려진 일정 교결량(constant-cement) 모델을 북해 유전의 검층 자료에 적용하여 암석 물리 견본(rock physics template)을 완성했다. 마지막으로 이 암석 물리 견본과 현장 2D 탄성파 자료의 중합전 역산 결과로부터 이 유전의 저류암과 덮개암, 공극 유체 분포를 예측해 보았다.

Effects of initial imperfections on nonlinear behaviors of thin-walled members

  • Ohga, M.;Takaue, A.;Shigematsu, T.;Hara, T.
    • Structural Engineering and Mechanics
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    • 제11권5호
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    • pp.519-534
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    • 2001
  • The effect of the initial imperfections on the nonlinear behaviors and ultimate strength of the thin-walled members subjected to the axial loads, obtained by the finite element stability analysis, are examined. As the initial imperfections, the bucking mode shapes of the members are adopted. The buckling mode shapes of the thin-walled members are obtained by the transfer matrix method. In the finite element stability analysis, isoparametric degenerated shell element is used, and the geometrical and material nonlinearity are considered based on the Green Lagrange strain definition and the Prandtl-Reuss stress-strain relation following the von Mises yield criterion. The U-, box- and I-section members subjected to the axial loads are adopted for numerical examples, and the effects of the initial imperfections on the nonlinear behaviors and ultimate strength of the members are examined.