• 제목/요약/키워드: radius problem

검색결과 265건 처리시간 0.026초

밀폐된 단일 회전 원판 주위의 유동손실에 관한 연구 (A study on the flow friction loss of a shrouded rotating disk)

  • 조성욱;임윤철
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 2001년도 제34회 추계학술대회 개최
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    • pp.159-165
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    • 2001
  • The fundamental fluid mechanics associated with the rotation of a smooth plane disk enclosed within a cylindrical chamber have been studied experimentally. In order to acquire systematic information pertinent to this problem torque and friction loss data were obtained over a wide range of disk Reynolds numbers for axial clearance-disk radius ratio H/R from 0.025 to 0.2 and radial tip gap-disk radius ratio s/R from 0.021 to 0.105. Loss analysis of hard disk drive(HDD) is presented to describe the contribution of windage loss of a rotating disk. The minimum loss from factor of HDD can be obtained from this analysis at each operation conditions.

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미소균열측정과 성장특성에 관한 연구 (A Study of Small Fatigue Crack Measurement and Crack Growth Characteristics)

  • 이종형;소윤섭;김윤곤;임춘규;이상영
    • 한국산업융합학회 논문집
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    • 제10권1호
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    • pp.39-46
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    • 2007
  • The objective of this paper is to examine the detection limit, growth characteristics and notch curvature radius in short crack problem. Measurement techniques such as ultrasonic method and back-face strain compliance method were adapted. The fatigue crack growth rate of the short crack is slower than that of a long crack for a notched specimen. The short crack is detected effectively by ultrasonic method. A short surface crack occurs in the middle of specimen thickness and is transient to a through crack when maximum crack depth is larger than the notch curvature radius.

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등식 $\frac{1}{h_a}+\frac{1}{h_b}+\frac{1}{h_c}=\frac{1}{r}$의 다양한 증명방법에 대한 연구 (A Study on Various Proofs of Equality $\frac{1}{h_a}+\frac{1}{h_b}+\frac{1}{h_c}=\frac{1}{r}$)

  • 이재갑;한인기
    • 한국학교수학회논문집
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    • 제10권4호
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    • pp.519-533
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    • 2007
  • 본 연구에서는 삼각형의 높이 및 내접원의 반지름에 대한 한 등식을 증명하기 위한 다양한 탐색수행의 방향을 기술하였고, 이를 바탕으로 등식에 대한 다양한 증명방법을 제시하였다. 이를 통해, 체계적인 탐색수행을 통한 다양한 풀이방법 발명의 한 예를 제시하였으며, 다양한 풀이방법에 대한 수학교수학적 논의의 방향과 폭을 확장시킬 수 있는 기초 자료가 될 것으로 기대된다.

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원공(圓孔)을 갖는 원통(圓筒) Shell의 좌굴해석(挫屈解析) (Buckling Analysis of Cylindrical Shells with a Hole)

  • 임장근;강병식
    • 대한조선학회지
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    • 제22권1호
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    • pp.1-8
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    • 1985
  • The buckling characteristics of cylindrical shells with a circular hole, under axially compressed loads, have been analyzed and the results have been compared with existed experimental results. Deflection function with decay factor is assumed, and stress distribution around a circular hole in tensioned infinite plate is used for formulating buckling energy function. Applying Rayleigh Ritz procedure to this energy function, characteristic equation of eigenvalue problem is determined. Buckling load is defined by the minimum value of eigenvalues calculated according to several decay factors, and as the radius ratios of a circular hole (a/R) and shell thickness ratios (R/t) are varied, the reducing characteristics of buckling load are studied. As a result, buckling loads are reduced by about 50% according to some radius ratios ($a/R{\geq}0.15$) of circular hole and are not nearly affected by shell thickness ratio(R/t).

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INCLUSION RELATIONS AND RADIUS PROBLEMS FOR A SUBCLASS OF STARLIKE FUNCTIONS

  • Gupta, Prachi;Nagpal, Sumit;Ravichandran, Vaithiyanathan
    • 대한수학회지
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    • 제58권5호
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    • pp.1147-1180
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    • 2021
  • By considering the polynomial function 𝜙car(z) = 1 + z + z2/2, we define the class 𝓢*car consisting of normalized analytic functions f such that zf'/f is subordinate to 𝜙car in the unit disk. The inclusion relations and various radii constants associated with the class 𝓢*car and its connection with several well-known subclasses of starlike functions is established. As an application, the obtained results are applied to derive the properties of the partial sums and convolution.

Closed-form solution of axisymmetric deformation of prestressed Föppl-Hencky membrane under constrained deflecting

  • Lian, Yong-Sheng;Sun, Jun-Yi;Dong, Jiao;Zheng, Zhou-Lian;Yang, Zhi-Xin
    • Structural Engineering and Mechanics
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    • 제69권6호
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    • pp.693-698
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    • 2019
  • In this study, the problem of axisymmetric deformation of prestressed $F{\ddot{o}}ppl-Hencky$ membrane under constrained deflecting was analytically solved and its closed-form solution was presented. The small-rotation-angle assumption usually adopted in membrane problems was given up, and the initial stress in membrane was taken into account. Consequently, this closed-form solution has higher calculation accuracy and can be applied for a wider range in comparison with the existing approximate solution. The presented numerical examples demonstrate the validity of the closed-form solution, and show the errors of the contact radius, profile and radial stress of membrane in the existing approximate solution brought by the small-rotation-angle assumption. Moreover, the influence of the initial stress on the contact radius is also discussed based on the numerical examples.

Axisymmetric bending of a circular plate with stiff edge on a soft FGM layer

  • Volkov, Sergey S.;Litvinenko, Alexander N.;Aizikovich, Sergey M.;Wang, Yun-Che;Vasiliev, Andrey S.
    • Structural Engineering and Mechanics
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    • 제59권2호
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    • pp.227-241
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    • 2016
  • A circular plate with constant thickness, finite radius and stiff edge lying on an elastic halfspace is considered. The half-space consists of a soft functionally graded (FGM) layer with arbitrary varying elastic properties and a homogeneous elastic substrate. The plate bends under the action of arbitrary axisymmetric distributed load and response from the elastic half-space. A semi-analytical solution for the problem effective in whole range of geometric (relative layer thickness) and mechanical (elastic properties of coating and substrate, stiffness of the plate) properties is constructed using the bilateral asymptotic method (Aizikovich et al. 2009). Approximated analytical expressions for the contact stresses and deflections of the plate are provided. Numerical results showing the qualitative dependence of the solution from the initial parameters of the problem are obtained with high precision.

FAST ONE-PARAMETER RELAXATION METHOD WITH A SCALED PRECONDITIONER FOR SADDLE POINT PROBLEMS

  • OH, SEYOUNG;YUN, JAE HEON
    • Journal of applied mathematics & informatics
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    • 제34권1_2호
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    • pp.85-94
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    • 2016
  • In this paper, we first propose a fast one-parameter relaxation (FOPR) method with a scaled preconditioner for solving the saddle point problems, and then we present a formula for finding its optimal parameter. To evaluate the effectiveness of the proposed FOPR method with a scaled preconditioner, numerical experiments are provided by comparing its performance with the existing one or two parameter relaxation methods with optimal parameters such as the SOR-like, the GSOR and the GSSOR methods.

OPERATORS SIMILAR TO NORMALOID OPERATORS

  • Zhu, Sen;Li, Chun Guang
    • 대한수학회지
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    • 제48권6호
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    • pp.1203-1223
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    • 2011
  • In this paper, the authors investigate the structure of operators similar to normaloid and transloid operators. In particular, we characterize the interior of the set of operators similar to normaloid (transloid, respectively) operators. This gives a concise spectral condition to determine when an operator is similar to a normaloid or transloid operator. Also it is proved that any Hilbert space operator has a compact perturbation with transloid property. This is used to give a negative answer to a problem posed by W. Y. Lee, concerning Weyl's theorem.