• Title/Summary/Keyword: Nodal Angle

Search Result 28, Processing Time 0.027 seconds

Fabrication of the focal length and distortion measurement system (초점길이 및 왜곡수차 측정장치 제작)

  • 조현모
    • Proceedings of the Optical Society of Korea Conference
    • /
    • 1990.02a
    • /
    • pp.82-86
    • /
    • 1990
  • A camera type optical bench system equipped with a lens collimator and an image analyzer is fabricated to measure the equivalent focal length and distortion of lenses. This system is automatized by the computer which controls stepping motors. A nodal slide optical bench system equipped with an off axis reflective collimator is fabricated and improved by using rotating arms and air bearing system. distortion measurement on a wide angle lens using the camera method and the nodal slide method is reported. Defocusing error in the distortion measurement with the nodal slide optical bench is analyzed and improved by iteration method to search the correct image point.

  • PDF

A Study on the Stress Analysis ofAxi-symetric Body with N on-symetric Load and N on-symetric Given Displacements (비대칭 하중을 받고 비대칭 변위가 주어진 축대칭 물체의 응력해석에 관한 연구)

  • 전효중;왕지석;최순열
    • Journal of Advanced Marine Engineering and Technology
    • /
    • v.14 no.4
    • /
    • pp.46-56
    • /
    • 1990
  • Stress analysis of axi-symetric body with non-symetric loading and non-symetric given displacements is investigated in this paper using the finite element method. As the non-symetric load and non-symetric given displacements of axi-symetric body are generally periodic functions of angle .theta., the nodal forces and nodal displacements can be expanded in cosine and sine series, that is, Fourier series. Furthermore, using Euler's formula, the cosine and sine series can be converted into exponential series and it is prooved that the related calculus become more clear. Substituting the nodal displacements expanded in Fourier series into the strain components of cylindrical coordinates system, the element strains are expressed in series form and by the principal of virtual work, the element stiffness martix and element load vector are obtained for each order. It is also showed that if the non-symetric loads are even or odd functions of angle ${\theta}$ the stiffness matrix and load vector of the system are composed with only real numbers and relatively small capacity fo computer memory is enough for calculation.

  • PDF

An Analysis of the Reinforced Concrete Circular Ring Sector Plates with Arbitrary Boundary Conditions (I) - Part I Effects of open-angle - (임의의 경계조건을 갖는 철근 콘크리트 선형판의 해석 -제1보 개각의 영향)

  • 조진구
    • Magazine of the Korean Society of Agricultural Engineers
    • /
    • v.33 no.2
    • /
    • pp.94-103
    • /
    • 1991
  • This study was carried out to investigate the engineering characteristics of the R.C circular ring sector plate with various boundary conditions and then to propose a rational and paraical method for application of finite element method to R.C structures. The stiffness matrix of the circular ring sector plate was obtained by using the multi-base coordinate system in which the base-coordinate systems were constructed for each nodal point of the quadrilateral element in order to reflect the complicated boundary conditions conveniently and correctly. The R.C element stiffness matrix was constructed by adding the stiffness coefficients of the steel-bar element into the plate bending element stiffness matrix. Herein, the steel-bar element was treated as the common beam element. Using the above method, the effects of steel-bar can be considered without increasing of the numbers of element and nodal points.

  • PDF

Free Vibration Analysis of Annular Sector Plates Using Time Average Holographic Interferometer (시간평균 홀로그래픽 간섭계를 이용한 환형 평판의 자유 진동 연구)

  • 나종문
    • Journal of Advanced Marine Engineering and Technology
    • /
    • v.22 no.3
    • /
    • pp.353-361
    • /
    • 1998
  • The study on the vibration characteristics of annular sector plates is important for structural engineers. In this study the vibration modes and their natural frequencies of annular sector plates clamped along the inner circumferential edge are obtained by the time average holographic interferometer according to the varying sector angle. The experimental results agree well with those obtained by the numerical analysis. The vibration characteristics of annular sector plates shows great dependence on the sector angle. The radial nodal lines converge to the center of annular sector plate.

  • PDF

Overview of Tidal Phase-lag References Used in Korea (우리나라 조석지각 기준 표기에 대한 고찰)

  • Byun, Do-Seong
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
    • /
    • v.12 no.3
    • /
    • pp.234-238
    • /
    • 2007
  • Three different tidal phase-lag references have been used by the tidal research community of Korea: Greek kappa (k), Local standard time zone ($135^{\circ}E$) phase-lag (g) and Greenwich phase-lag (G). This ununified tidal information system may induce confusion in understanding tidal characteristics and their variability and impede the development of tidal knowledge in Korea. In this study we closely explore the three phase-lag reference definition with respect to their mutual conversion. We also identify an incorrect phase-lag reference definition used in previous works and discuss what has led to this misunderstanding.

$F_N$-Based Nodal Transport Method in X-Y Geometry

  • Hong, Ser-Gi;Cho, Nam-Zin
    • Proceedings of the Korean Nuclear Society Conference
    • /
    • 1996.11a
    • /
    • pp.39-44
    • /
    • 1996
  • A nodal transport method based on the F$_{N}$ method is developed for the transport calculation in x- y geometry and tested for benchmark problems. Using transverse integration, the two-dimensional transport equation is converted to one-dimensional equations for x, y-directions and the one-dimensional equations are integrated over azimuthal angle. With proper approximations for the transverse leakage, the one-dimensional equations are discretized by using the F$_{N}$ method without truncation error. At present, isotropic approximation of the transverse with a quadratic or flat shape in spatial variable is tested.ted.

  • PDF

A finite element based approach to observe hydrodynamic pressure in reservoir adjacent to concrete gravity dam

  • Santosh Kumar, Das;Kalyan Kumar, Mandal;Arup Guha, Niyogi
    • Ocean Systems Engineering
    • /
    • v.12 no.4
    • /
    • pp.385-402
    • /
    • 2022
  • This paper deals with the study of hydrodynamic pressure in reservoir adjacent to the concrete gravity dam subjected to dynamic excitation. Widely famous finite element method is used to discretize the reservoir domain for modelling purpose. Pressure is considered as nodal variable following Eulerian approach. A suitable nonreflecting boundary condition is applied at truncated face of reservoir to make the infinite reservoir to finite one for saving the computational cost. Thorough studies have been done on generation of hydrodynamic pressure in reservoir with variation of different geometrical properties. Velocity profile and hydrodynamic pressure are observed due to harmonic excitation for variation of inclination angle of dam reservoir interface. Effect of bottom slope angle and inclined length of reservoir bottom on hydrodynamic pressure coefficient of reservoir are also observed. There is significant increase in hydrodynamic pressure and distinct changes in velocity profile of reservoir are noticeable for change in inclination angle of dam reservoir interface. Change of bottom slope and inclined length of reservoir bottom are also governing factor for variation of hydrodynamic pressure in reservoir subjected to dynamic excitation.

Effects of Blade Shape on the Dynamics of Turbo-machinery (깃 형상이 터보기계의 동특성에 미치는 영향)

  • 전상복
    • Journal of KSNVE
    • /
    • v.8 no.3
    • /
    • pp.477-484
    • /
    • 1998
  • An analytical procedure on the base of the substructure synthesis and assumed modes method is developed to investigate the flexibility effect of bladed disk assembly on vibrational modes of flexible rotor system. In modeling the system, Coriolis forces, gyroscopic moments, and centrifugal stiffening effects are taken into account. The coupled vibrations between the shaft and bladed disk are then extensively investigated through the numerical simulation of simplified models, with varying the shaft rotational speed and the prewist and stagger angles of the blade. It is found that the Coriolis and inertia forces and the inertia torque, which are induced by the one nodal diameter modes of the bladed disk and vary depending upon the stagger and prewist angles, lead to the coupled motions of the shaft and the bladed disk.

  • PDF

Free Vibration Analysis of Annular Sector Plates Psing Pime Average Holographic Interferometry (시간 평균 홀로그래픽 간섭계를 이용한 환형 평판의 자유 진동 연구)

  • 이기백;김정훈;나종문
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 1996.10a
    • /
    • pp.414-421
    • /
    • 1996
  • The study of the vibration characteristics of annular sector plates which are clamped along their inner circumferential edge is important for structural engineers. The present analysis consists of experimental method and numerical method. The experimental method using time-average holographic interferometry is obtained vibration modes and frequencies. The experimental results are verified by a numerical method using F.E.M. The important aspects of the present paper is the dependence of the natural frequencies and the mode shape on the annular area changing sector angle. The radial nodal lines converge to the center of the plate. As increasing sector angle, the radial modes are predominant.

  • PDF

Effects of Stagger and Pretwist Angles on the Vibration of Flexible Shaft-Bladed Disk Systems (탄성 축-익 붙임 원판 계의 진동에 있어서 엇각 및 비틀림각의 영향)

  • 전상복;이종원
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 1997.10a
    • /
    • pp.101-109
    • /
    • 1997
  • An analytical procedure on the base of the substructure synthesis and assumed modes method is developed to investigate the flexibility effect of bladed disk assembly on vibrational modes of flexible rotor system. In modeling the system, Coriolis forces, gyroscopic moments, and centrifugal stiffening effects are taken into account. The coupled vibrations between the shaft and bladed disk are then extensively investigated through the numerical simulation of simplified models, with varying the shaft rotational speed and the pretwist and stagger angles of the blade. It is found that the Coriolis and inertia forces and the inertia torque, which are induced by the one nodal diameter modes of the bladed disk and vary depending upon the stagger and pretwist angles, lead to the coupled motions of the shaft and the bladed disk.

  • PDF