• 소음진동
• /
• 제6권6호
• /
• pp.735-747
• /
• 1996

In this paper, buckling reliability analyses of stiffened cylinder with random initial geometric imperfection under axial impact load are performed by the combined response surface method. The effect of random geometric imperfection on the failure probability and reliability is recognized quantitatively. Buckling reliability decreases with the increase of mean value, cov of initial geometric imperfection under the same external load. Buckling probability under impact load is greater than those under static load with the same condition. From the probabilistic characteristics of imapct buckling load, relation between reliability index and safety parameter can be obtained in addition to the relation between load and reliability index. And those results can be used to determine the range of required safety parameter and acceptable imperfaction.

• 대한원격탐사학회지
• /
• 제19권3호
• /
• pp.247-253
• /
• 2003

The mainly used technique to correct satellite images with geometric distortion is to develop a mathematical relationship between pixels on the image and corresponding points on the ground. Polynomial models with various transformations have been designed for defining the relationship between two coordinate systems. GCP based geometric correction has peformed overall plane to plane mapping. In the overall plane mapping, overall structure of a scene is considered, but local variation is discarded. The Region with highly variant height is rectified with distortion on overall plane mapping. To consider locally variable region in satellite image, TIN-based rectification on a satellite image is proposed in this paper. This paper describes the relationship between GCP distribution and rectification model through experimental result and analysis about each rectification model. We can choose a geometric correction model as the structural characteristic of a satellite image and the acquired GCP distribution.

• 제어로봇시스템학회논문지
• /
• 제21권7호
• /
• pp.648-653
• /
• 2015

The kinematics with the instantaneous motion and statics of a manipulator has generally been proven algebraically. The algebraic solutions give very simple and straightforward results but the solutions do not have any meaning in physics or geometry. Therefore it is not easy to extend the algebraic results to design or control a robotic manipulator efficiently. Recently, geometrical approach to define the instantaneous motion or static relation of a manipulator is popularly researched and the results have very strong advantages to have a physical insight in the solution. In this paper, the instantaneous motion and static relation of a planar manipulator are described by geometrical approach, specifically by an axis screw and a line screw. The mass center of a triangle with weight and a perpendicular distance between the two screws are useful geometric measures for geometric analysis. This study provides a geometric interpretation of the kinematics and statics of a planar manipulator, and the method can be applied to design or control procedure from the geometric information in the equations.

• 한국조경학회지
• /
• 제28권2호
• /
• pp.71-84
• /
• 2000

In this study, design characteristics of Village Parks in Seoul are investigated through an analysis of structuring themes expressed in spatial design. The goals and objectives of this study are: to emphasize the significance of design themes; and to demonstrate an approach to the design of landscapes through an analysis of structuring themes. For conducting this study, geometric forms and naturalistic forms were examined first. That is, the following 15 structuring themes were examined, as guiding themes: the 90$^{\circ}$rectangular theme; the 45$^{\circ}$/90$^{\circ}$angular theme; the 30$^{\circ}$/60$^{\circ}$ angular theme; circles on circle; concentric circles and radii; arcs and tangents; circle segments; the ellipse; the spiral; the meander; the free ellipse and scallops; the free spiral; the irregular polygon; the organic edge; and clustering and fragmentation. Forty five Village Parks in Seoul, built between 1996 and 1997, were analyzed through these 15 structuring themes. An analysis of Village Parks was conducted by the following two categories: land shape and structuring themes; and design directions and structuring themes. The research results are as follows; 1) Geometric forms are more frequently applied than naturalistic forms. 2) Regardless of land shape, geometric forms derived from simple primary shapes, the square and the circle, are frequently used. And the meander and the irregular polygon among naturalistic forms are frequently used. 3) Regarding design directions and structuring themes, design concepts, symbolic meanings and spatial forms are, to some degree, integrated. 4) The spiral is not applied among geometric forms. And the meander and the irregular polygon, as naturalistic forms, are frequently utilized. Research findings obtained from this study could be used in the designing of future Village Parks. For a profound study, future, research is needed in two-dimensional plans and three-dimensional elements of Village Parks.

• 대한기계학회논문집
• /
• 제16권4호
• /
• pp.684-695
• /
• 1992

본 연구에서는 3차원 형상의 금형에 의한 박판금속 성형 공정을 에너지법으로 해석함에 있어 스윕곡면(SWeep surface)을 통해 기하학적 형상을 효과적으로 표현하는 방법을 제안하고, 이를 직사각형 격막의 정수압벌징의 해석에 으용하여 이에 의한 결 과를 이미 보고된 자료와 비교함으로써 일반적인 박판 성형공정을 해석하는데 본 이론 의 적용 가능성에 대하여 논의하고자 한다.

• 한국자동차공학회논문집
• /
• 제5권5호
• /
• pp.197-212
• /
• 1997

The performance of a torque converter can be expressed by the performance parameters such as flow radius and flow angle, on the mean flow path. The geometric analysis of the torque converter is required to determine these parameters for the modeling of the torque converter. In general, the blade shape is depicted by three dimensional data at the mid-surface of blade or those of the pressure and suction side. To generate three dimensional model of the blade using the data mentioned above, a consistent data format and a shape generation algorithm are required. This paper presents a useful consistent data format of the blades and an algorithm for the geometrical shape generation. By the geometric analysis program to which the shape generation algorithm is embedded, the variation of blade angles in rotating element analyzed. Then finally, the analyzed results of geometric profile of a blade are compared with those of the blade design principle, so called forced vortex theorem.

• 대한산업공학회지
• /
• 제31권1호
• /
• pp.36-43
• /
• 2005

It is the basic requirement of design process of parts assembly to specify geometric dimensions and tolerances of product characteristics. Among them, tolerance stack analysis is one of the important methods to specify tolerance zone. Tolerance stack analysis is to calculate gap using tolerances which includes geometric and coordinate dimensions. In this study, we suggested more general method called the virtual method to analyze tolerance stack. In virtual method, tolerance zone is formed by combination of dimensional tolerance, geometric tolerance and bonus tolerance. Also tolerance zone is classified by virtual boundary condition and resultant boundary condition. So gap can be defined by combination of virtual boundary and/or resultant boundary. Several examples are used to show the effectiveness of new method comparing to other methods.

• Wind and Structures
• /
• 제23권6호
• /
• pp.485-503
• /
• 2016

To investigate the nonlinear aerostatic stability of the Hutong cable-stayed rail-cum-road bridge with ultra-kilometer main span, a FEM bridge model is established. The tri-component wind loads and geometric nonlinearity are taken into consideration and discussed for the influence of nonlinear parameters and factors on bridge resistant capacity of aerostatic instability. The results show that the effect of initial wind attack-angle is significant for the aerostatic stability analysis of the bridge. The geometric nonlinearities of the bridge are of considerable importance in the analysis, especially the effect of cable sag. The instable mechanism of the Hutong Bridge with a steel truss girder is the spatial combination of vertical bending and torsion with large lateral bending displacement. The design wind velocity is much lower than the static instability wind velocity, and the structural aerostatic resistance capacity can meet the requirement.

• 한국공간구조학회:학술대회논문집
• /
• 한국공간구조학회 2005년도 춘계학술발표회 및 정기총회 2권1호(통권2호)
• /
• pp.125-132
• /
• 2005

Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The material property of the membrane has strong axial stiffness, but little bending stiffness. The design procedure of membrane structures are needed to do shape finding, stress-deformation analysis and cutting pattern generation. In shape finding, membrane structures are unstable structures initially. These soft structures need to be introduced initial stresses because of its initial unstable state, and it happens large deformation phenomenon. And also there are highly varied in their size, curvature and material stiffness. So, the approximation inherent in cutting pattern generation methods is quite different. Therefore, in this study, to find the structural shape after large deformation caused by Initial stress, we need the shape analysis considering geometric nonlinear ten And the geodesic line on surface of initial equilibrium shape and the cutting pattern generation using the geodesic line is introduced.

• Structural Engineering and Mechanics
• /
• 제54권4호
• /
• pp.809-827
• /
• 2015

In this paper, seismic energy response of inelastic steel structures under earthquake excitations is investigated. For this purpose, a numerical procedure based on nonlinear dynamic analysis is developed by considering material, geometric and connection nonlinearities. Material nonlinearity is modeled by the inversion of Ramberg-Osgood equation. Nonlinearity caused by the interaction between the axial force and bending moment is also defined considering stability functions, while the geometric nonlinearity caused by axial forces is described using geometric stiffness matrix. Cyclic behaviour of steel connections is taken into account by employing independent hardening model. Dynamic equation of motion is solved by Newmark's constant acceleration method in the time history domain. Energy response analysis of space frames is performed by using this proposed numerical method. Finally, for the first time, the distribution of the different energy types versus time at the duration of the earthquake ground motion is obtained where in addition error analysis for the numerical solutions is carried out and plotted depending on the relative error calculated as a function of energy balance versus time.