• 한국철도학회논문집
• /
• 제6권1호
• /
• pp.58-65
• /
• 2003

Wheel/Rail geometric constraint relationships, such as effective conicity and gravitational stiffness, strongly influence the lateral dynamics of railway vehicles. In general, these geometric contact characteristics are nonlinear functions of the wheelset lateral displacement. There is a need to develop a wheel/rail geometric contact simulation program for wheels and rails with arbitrary profiles for the prediction of the dynamic behavior of railway vehicles. An algorithm to simulate any combination of wheels and rails is employed and a GUI for easy analysis is constructed. The simulation program is applied to KTX which will run on both KTX and conventional rails, two rail standards having different rail profiles. The results show that the two rail systems have different geometric contact characteristic

• 대한수학회지
• /
• 제55권4호
• /
• pp.897-921
• /
• 2018

Given bounded pseudoconvex domains in 2-dimensional complex Euclidean space, we derive analytical and geometric conditions which guarantee the Diederich-$Forn{\ae}ss$ index is 1. The analytical condition is independent of strongly pseudoconvex points and extends $Forn{\ae}ss$-Herbig's theorem in 2007. The geometric condition reveals the index reflects topological properties of boundary. The proof uses an idea including differential equations and geometric analysis to find the optimal defining function. We also give a precise domain of which the Diederich-$Forn{\ae}ss$ index is 1. The index of this domain can not be verified by formerly known theorems.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제2권4호
• /
• pp.177-184
• /
• 2010

In this study, geometric modeling techniques and their application to ship modeling and design are presented. Traditionally the hull shape is defined by using curves called the lines and various necessary computations are performed based on the discrete points obtained from the lines. However, some applications find difficulty in using the lines such as seakeeping analysis, which requires the computation of wetted part that is changing dynamically over time. To overcome such a problem and increase accuracy and efficiency in computation, two essential geometric modeling techniques, surface modeling and surface-to-surface intersection, are introduced and their application to ship modeling and analysis including hydrostatic computation, slamming and seakeeping analyses is presented.

• 대한기계학회논문집A
• /
• 제27권2호
• /
• pp.262-267
• /
• 2003

Error of the geometric series expansion method for the structural sensitivity analysis is estimated. Although the semi-analytic method has several advantages, accuracy of the method prevents it from practical application. One of the promising remedies is the use of geometric series formula for the matrix inversion. Its result of the sensitivity analysis converges that of the global difference method which is known as reliable one. To reduce computational efforts and to obtain reliable results, it is important to know how many terms need to expand. In this paper, the error formula is presented and Its usefulness is illustrated through numerical experiments.

• 대한기계학회논문집
• /
• 제17권12호
• /
• pp.2915-2925
• /
• 1993

A finite element program using degenerated shell element was developed to solve the geometric, material and combined nonlinear behaviors of composite laminated plates. The total Lagrangian method was implemented for geometric nonlinear analysis. The material nonlinear behavior was analyzed by considering the matrix degradation due to the progressive failure in the matrix and matrix-fiber interface after initial failure. The results of the geometric nonlinear analyses showed good agreements with the other exact and numerical solutions. The results of the combined nonlinear analyses considered both geometric and material nonlinear behaviors were compared to the experiments in which a concentrated force was applied to the center of the square laminated plate with clamped four edges.

• 한국정밀공학회지
• /
• 제25권5호
• /
• pp.69-76
• /
• 2008

Inner diameter of bearing race is automatically measured by complete inspection system after grinding process. Contact type three points supporting method is widely applied to automatic inner diameter measurement because of its excellent stability. However, the geometric consideration regarding three points supporting method is not sufficient. In this study, the error equation from geometric error analysis of three points supporting method is found. The effect of factors in the error equation is also investigated. The error equation is linear for difference of diameter in sample and master on range of tolerance. An error becomes more and more larger, when the distance of two supporting balls or the diameter of supporting ball are increased. In the result, some considerations are proposed for measurement of inner diameter by the three points supporting method.

• 한국산학기술학회논문지
• /
• 제19권6호
• /
• pp.355-364
• /
• 2018

본 연구의 목적은 대학생들의 의사소통능력을 향상시키기 위한 프로그램을 개발하기 위한 기초연구로서 도형심리유형과 의사소통능력과의 관계에서 긍정심리자본이 매개할 수 있는지 확인해보는 것이다. 이를 위해 전국의 대학생들 321명을 대상으로 설문조사하였으며 척도의 신뢰도분석, 회귀분석, 경로분석으로 자료를 분석하였다. 회귀분석을 통해 도형심리유형, 긍정심리자본, 의사소통능력의 변수들이 서로 긍정적인 회귀결과로 나타났다. 경로분석을 통해 도형심리 유형과 의사소통능력과의 관계에서 긍정심리자본이 매개역할을 하는 것을 확인하였으며 그 결과는 도형심리의 각 유형에 따라 다른 양상을 보였다. 동그라미 유형은 의사소통능력에 대하여 긍정심리자본의 하위인 복원력을 매개하거나 직접적으로 영향을 미치고 있으며 세모 유형은 의사소통능력에 대하여 긍정심리자본의 하위요인인 자기효능감과 복원력을 매개해 영향을 미치는 것으로 나타났다. 네모 유형은 의사소통능력에 대하여 긍정심리자본의 하위요인인 자기효능감을 매개하거나 직접적으로 영향을 미치고 있으며 에스 유형은 의사소통능력에 대하여 긍정심리자본을 매개하지 않고 직접적으로만 영향을 미치는 것으로 나타났다. 따라서 대학생들을 위한 의사소통향상프로그램을 개발하기 위해서는 위와 같은 결과를 고려하여 도형심리유형별로 긍정심리자본이 적용된 프로그램을 개발할 수 있을 것이다.

• Journal of applied mathematics & informatics
• /
• 제34권1_2호
• /
• pp.75-84
• /
• 2016

The objective of this work is to perform a geometric analysis of the net present value (NPV) and Internal Rate of Return (IRR), defining analytics and in verifying the relationship between geometric properties of such functions. For this simulation, was used the values of the cash flows for each period identical and equal to US$ 200.00 cash, the initial investment US$ 1,000.00 and investments of each identical and equal to US$ 50.00 period. In addition, the discount rate and time were considered a maximum of 2 years (24 months) at a rate between 0 and 100%. The geometric analysis of the characteristics obtained from the expressions of the Net Present Value and Internal Rate of Return possible to observe that besides the analytical dependence between these quantities , the geometric relationships are relevant when studied in relation to the zero NPV and expressed a great contribution the sense of a broad vision for the administrator in the analysis of analytical variables that in uences the balance sheet of the company.

• Structural Engineering and Mechanics
• /
• 제17권6호
• /
• pp.751-766
• /
• 2004

This paper extends the use of the hierarchic degenerated shell element to geometric non-linear analysis of composite laminated skew plates by the p-version of the finite element method. For the geometric non-linear analysis, the total Lagrangian formulation is adopted with moderately large displacement and small strain being accounted for in the sense of von Karman hypothesis. The present model is based on equivalent-single layer laminate theory with the first order shear deformation including a shear correction factor of 5/6. The integrals of Legendre polynomials are used for shape functions with p-level varying from 1 to 10. A wide variety of linear and non-linear results obtained by the p-version finite element model are presented for the laminated skew plates as well as laminated square plates. A numerical analysis is made to illustrate the influence of the geometric non-linear effect on the transverse deflections and the stresses with respect to width/depth ratio (a/h), skew angle (${\beta}$), and stacking sequence of layers. The present results are in good agreement with the results in literatures.

• Structural Engineering and Mechanics
• /
• 제20권6호
• /
• pp.609-630
• /
• 2005

A reliability analysis method is proposed in this paper through a combination of the advantages of the response surface method (RSM), finite element method (FEM), first order reliability method (FORM) and the importance sampling updating method. The accuracy and efficiency of the method is demonstrated through several numerical examples. Then the method is used to estimate the serviceability reliability of cable-stayed bridges. Effects of geometric nonlinearity, randomness in loading, material, and geometry are considered. The example cable-stayed bridge is the Second Nanjing Bridge with a main span length of 628 m built in China. The results show that the cable sag that is part of the geometric nonlinearities of cable-stayed bridges has a major effect on the reliability of cable-stayed bridge. Finally, the most influential random variables on the reliability of cable-stayed bridges are identified by using a sensitivity analysis.