• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.67-70
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• 2003

To develop an effective geometric modeling is essential in order that precise mechanical properties and the geometrical properties of the 3-D braided composites can be estimated. RVE(representative volume element) was adopted fur geometrical modeling. RVE consisted of IC(inner unit cell), ISUC(interior surface unit cell) and ESUC(exterior surface unit cell). The whole geometrical model fur hybrid 3-D braided composites was developed.

• Structural Engineering and Mechanics
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• 제47권1호
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• pp.27-44
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• 2013

A finite element computational procedure for the accurate analysis of quasistatic thermorheological complex structures response is developed. The geometrical nonlinearity, arising from large displacements and rotations (but small strains), is accounted for by the total Lagrangian description of motion. The Schapery's nonlinear single-integral viscoelastic constitutive model is modified for a time-stress-temperature-dependent behavior. The nonlinear thermo-viscoelastic constitutive equations are incrementalized leading to a recursive relationship and thereby the resulting finite element equations necessitate data storage from the previous time step only, and not the entire deformation history. The Newton-Raphson iterative scheme is employed to obtain a converged solution for the non-linear finite element equations. The developed numerical model is verified with the previously published works and a good agreement with them is found. The applicability of the developed model is demonstrated by analyzing two examples with different thermal/mechanical loading histories.

• 한국지능정보시스템학회:학술대회논문집
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• 한국지능정보시스템학회 2000년도 춘계정기학술대회 e-Business를 위한 지능형 정보기술 / 한국지능정보시스템학회
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• pp.197-206
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• 2000

We proposed a negotiation model for the n:n negotiation process in the deal. The proposed model was based on the geometrical metaphor concept. We suggested also a negotiation state space using the metaphors where deals can be done conveniently and effectively. We analyzed and showed the usefulness of the model for the both parties concerned in the deal.

• 제어로봇시스템학회논문지
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• 제16권3호
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• pp.277-285
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• 2010

This paper describes an approach to analyze geometrical information of building images for understanding outdoor environment of autonomous navigation robot. Line segments and color information are used to classily a building with the other objects such as sky, trees, and roads. The line segments and their two neighboring regions are extracted from detected edges in image. The model of line segment (MLS) consists of color information of neighbor regions. This model rules out the line segments of non-building face. A building face converges into dominant vanishing points (DVPs) which include one vertical point and one of five horizontal points in maximum. The intersection of vertical and horizontal lines creates a facet of building. The geometrical characteristics such as the center coordinates, area, aspect ratio and aligned coexistence are used for extracting the windows in the building facet. In experiments, 150 building faces and 1607 windows were detected from the database of outdoor environment. We found that this result shows 94.46% detection rate. These experimental images were all taken in Ulsan metropolitan city in Korea under difference of viewpoints, daytime, camera system and weather condition.

• Structural Engineering and Mechanics
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• 제36권2호
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• pp.129-147
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• 2010

This study deals with the viability of using a designed geometrical model consists of plane, polar coordinates (PC) and span length in the determination of bridges deformation. The data of a Tianjin Yonghe bridge located in the southern part of China as collected by RTK-DGPS technique and Accelerometer were used in the analysis. Kalman filter and fast Fourier transformation (FFT) analyses were used to determine the frequency. The results indicate that the designed plane and PC geometrical model are easy to calculate the long-time structural deformation monitoring. In addition, the observed frequency using GPS with the rate of 20 Hz doesn't give correction natural frequency of the observation structures.

• Nuclear Engineering and Technology
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• 제54권9호
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• pp.3415-3421
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• 2022

This paper is aimed to find out the impact of the geometrical parameters, mainly the radius and the height of a cylinder, on the SGEMP response including the famous scaling law in the classical cylinder model using a homemade PIC code UNIPIC-3D. We computed the electric fields at the center and at the edge on the emission head face with different radii and heights under normal X-rays incidence. The results show that the electric field will increase with the radius but decrease with the height. We analyze the scaling law that links the electric field product and fluence product, and whereafter an irreconcilable contradiction raises when the radius is changeable, which limits the application range of the scaling law. Moreover, the field-height-radius relation is found and described by a combination of logarithmic and minus one-quarter numerical fitting law firstly. Particle and magnetic field distributions are used to explain all the behaviors of the fields reasonably. All the findings will assist the evaluation of SGEMP response in spacecraft protection.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1999년도 추계학술대회 논문집
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• pp.24-29
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• 1999

Proposed in this paper is a modeling and simulation methodology for a virtual manufacturing environment. Based on DEVS formalism[Zeigler 76], the proposed model, so called GKDEVS, is designed to descript the geometrical knematic structure as well as event-driven and continuous state dynamics. In terms of abstract simulation algorithm[Zeigler 84], the simulation method of GKDEVS is proposed for combined discrete-continuous simulation. Using the GKDEVS, and FMS model consisting of a turing machine, a 3-axis machine and a RGV-mounted robot is constructed and simulated.

• 한국컴퓨터그래픽스학회논문지
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• 제4권1호
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• pp.11-19
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• 1998

오일러 연산과 집합 연산과 같은 비다양체 위상 연산은 모델링의 다양한 환경을 제공한다. 이들 연산들은 주어진 모델의 위상 정보를 적합하게 유지하도록 하기 위하여 기하학적인 문제를 발생시킨다. 꼭지점, 모서리와 면과 같은 요소들이 서로 접촉할 때 이들 연산의 내부에서 수행되는 접합 연산은 비다양체 모델의 위상을 수정하는 기본적인 방법이다. 비다양체 모델을 접합할 때는 위상 관계를 추론하여야 한다. 위상 관계의 추론 방법은 위상학적인 방법과 기하학적인 방법의 2 가지 경우로 분류할 수 있다. 위상학적인 방법은 저장되어 있는 위상 정보만을 이용하여 위상 관계를 추론한다. 반면에, 기하학적인 방법은 접합이 일어나는 부분적인 영역에서 기하학적인 형상을 고려하여 위상의 관계를 찾아내는 방법이다. 본 연구에서는 이들 중에서 기하학적인 방법에 관하여 기술한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1148-1153
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• 2003

An adequate method for the prediction of machining errors is essential to improve productivity and product quality. But it is known that there is a remarkable difference between values calculated by conventional roughness model and measured values of actual machined surfaces under high efficient cutting condition. This paper introduces the theoretical analysis of characteristic lines of cut remainder to evaluate a geometrical surface roughness accurately. In this study, analytic equations of the characteristic lines are derived from the surface generation mechanism of ball end milling considering the actual trochoidal trajectories of cutting edges. The predicted results are compared with the results of conventional roughness model.

• Structural Engineering and Mechanics
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• 제59권3호
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• pp.431-454
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• 2016

In this paper, the nonlinear static and free vibration analysis of Euler-Bernoulli composite beam model reinforced by functionally graded single-walled carbon nanotubes (FG-SWCNTs) with initial geometrical imperfection under uniformly distributed load using finite element method (FEM) is investigated. The governing equations of equilibrium are derived by the Hamilton's principle and von Karman type nonlinear strain-displacement relationships are employed. Also the influences of various loadings, amplitude of the waviness, UD, USFG, and SFG distributions of carbon nanotube (CNT) and different boundary conditions on the dimensionless transverse displacements and nonlinear frequency ratio are presented. It is seen that with increasing load, the displacement of USFG beam under force loads is more than for the other states. Moreover it can be seen that the nonlinear to linear natural frequency ratio decreases with increasing aspect ratio (h/L) for UD, USFG and SFG beam. Also, it is shown that at the specified value of (h/L), the natural frequency ratio increases with the increasing the values amplitude of waviness while the dimensionless nonlinear to linear maximum deflection decreases. Moreover, with considering the amplitude of waviness, the stiffness of Euler-Bernoulli beam model reinforced by FG-CNT increases. It is concluded that the R parameter increases with increasing of volume fraction while the rate of this parameter decreases. Thus one can be obtained the optimum value of FG-CNT volume fraction to prevent from resonance phenomenon.