• Structural Engineering and Mechanics
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• 제57권2호
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• pp.281-294
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• 2016

The paper is devoted to study a mesh-free analysis method of structural elements of engineering structures based on B-spline Wavelet Basis Function. First, by employing the moving-least square method and the weighted residual method to solve the structural displacement field, the control equations and the stiffness equations are obtained. And then constructs the displacement field of the structure by using the m-order B-spline wavelet basis function as a weight function. In the end, the paper selects the plane beam structure and the structure with opening hole to carry out numerical analysis of deformation and stress. The Finite Element Method calculation results are compared with the results of the method proposed, and the calculation results of the relative error norm is compared with Gauss weight function as weight function. Therefore, the clarification verified the validity and accuracy of the proposed method.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.339-345
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• 1998

The creep of concrete structures caused by variable stresses is mostly calculated by step-by-step method based on the superposition of creep function. Although most practical application is carried out by this linear assumption, significant deviations between predictions and experiments have been observed when unloading takes place, that is, stress is reduced. The recovery is overestimated. The main purpose of this study is to present the application method of the creep analysis model which is expressed with both creep function and creep recovery function to concrete structures where is expressed with both creep function and creep recovery function to concrete structures where increase or decrease of stress is repeated . To apply two function method to time analysis of concrete structures, this study presents the calculation method of creep strain increment for stress variation. Then, this paper executes the time analysis for an example using suggested method, and compares theses results with the previous analysis values and experimental results.

• 한국CDE학회논문집
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• 제12권3호
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• pp.220-232
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• 2007

Current geometric modeling and analysis are commonly based on B-Rep modeling and a finite elements method respectively. Furthermore, it is difficult to represent an object whose material property is heterogeneous using the B-Rep method because the B-Rep is basically used for homogeneous models. In addition, meshes are required to analyze a property of a model when the finite elements method is applied. However, the process of generating meshes from B-Rep is cumbersome and sometimes difficult especially when the model is deformed as time goes by because the topology of deforming meshes are changed. To overcome those problems in modeling and analysis including homogeneous and heterogeneous materials, we suggest a unified modeling and analysis method based on implicit representation of the model using R-function which is suggested by Rvachev. For implicit modeling of an object a distance field is approximated and blended for a complex object. Using the implicit function mesh-free analysis is possible where meshes are not necessary. Generally mesh-free analysis requires heavy computational cost compared to a finite elements method. To improve the computing time of function evaluation, we utilize GPU programming. Finally, we give an example of a simple pipe design problem and show modeling and analysis process using our unified modeling and analysis method.

• 한국정보과학회논문지:소프트웨어및응용
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• 제33권8호
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• pp.655-667
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• 2006

본 논문은 목표 및 시나리오 기반의 요구사항을 이용하여 기능점수 (function point)를 산정하는 방법을 제안한다. 기능점수는 소프트웨어의 규모를 계산하는 방법으로 널리 사용되고 있으며 비용계산의 기본자료가 된다. 기능접수를 산정하기 위해서는 요구사항 도출 및 분석이 선행되어야 하나 기존의 기능점수 방법론은 이를 다루지 않고 있다. 한편 시스템 개발의 초기단계에서 대부분의 요구사항은 자연어 형태로 수집된다. 목표와 시나리오 방법론은 자연어 형태의 요구사항을 사용하여 요구사항을 도출하고 분석하는 방법으로 널리 사용되고 있으며 추적성에 대한 장점을 가지고 있다. 그러므로 목표 및 시나리오 기반의 요구사항으로부터 기능점수를 산정 할 수 있다면 요구사항과 기능접수 간의 추적성 관리가 쉬워진다. 이에 본 논문에서는 목표와 시나리오 기반의 요구사항으로부터 기능점수를 산정하는 방안을 제안한다. 제안된 방안은 자연어 형태로 기술된 목표 및 시나리오로부터 기능접수 분석에 필요한 규칙을 제공한다. 제안된 방안은 Order Processing System 예제를 통해 적용 방안을 설명한다.

• Journal of the Korean Statistical Society
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• 제35권2호
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• pp.213-224
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• 2006

We investigate the influence of subjects or observations on regression coefficients of generalized estimating equations using the influence function and the derivative influence measures. The influence function for regression coefficients is derived and its sample versions are used for influence analysis. The derivative influence measures under certain perturbation schemes are derived. It can be seen that the influence function method and the derivative influence measures yield the same influence information. An illustrative example in longitudinal data analysis is given and we compare the results provided by the influence function method and the derivative influence measures.

• International Journal of Precision Engineering and Manufacturing
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• 제4권2호
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• pp.64-70
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• 2003

A new method using a transfer function is introduced in the present paper for analyzing the motion errors of hydrostatic bearing tables. The relationship between film reaction force in a single-side hydrostatic pad and the form error of guide rail is derived at various spatial frequencies by finite element analysis, and it is expressed as a transfer function. This transfer function clarifies so called 'the averaging effect of an oil film' quantitively. It is found that the amplitude of film force is reduced as the spatial frequency increases or the relative width of the pocket is reduced. The motion errors of a multi pad type table are estimated using a transfer function, the form errors of a guide rail and the geometric relationship between the pads. The method is named as the Transfer Function Method (TFM). The motion errors calculated by the TFM show good agreement with the motion errors calculated by the Multi Pad Method considering the entire table as an analysis object. From the results, it is confirmed that the proposed TFM is very effective to analyze the motion errors of hydrostatic tables.

• Wind and Structures
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• 제27권3호
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• pp.149-161
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• 2018

A reliability analysis method is proposed in this paper based on the maximum entropy (MaxEnt) principle in which constraints are specified in terms of the fractional moments instead of integer moments. Then a multiplicative dimensional reduction method (M-DRM) is introduced to compute the fractional moments. The method is applicable for both explicit and implicit limit state functions of complex structures. After two examples illustrate the accuracy and efficiency of this method in comparison to the Monte Carlo simulation (MCS), the method is used to analyze the flutter reliability of suspension bridge. The results show that the empirical formula method in which the limit state function is explicitly represented as a function of variables is only a too conservative estimate for flutter reliability analysis but is not accurate adequately. So it is not suitable for reliability analysis of bridge flutter. The actual flutter reliability analysis should be conducted based on a finite element method in which limit state function is implicitly represented as a function of variables. The proposed M-DRM provide an alternate and efficient way to analyze a much more complicated flutter reliability of long span suspension bridge.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 춘계 학술논문 발표대회
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• pp.123-125
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• 2012

It is the important accurately to identify the needs of our customers in order to success the project. Requirements in the early stages of business is very abstract or not quantitative, and that will cause problems such as cost or schedule changes. Particularly many people are likely to prefer the early stages of the project, because the time of applying VE related cost savings is important. Owner's requirement analysis for project success in the VE process does not easy, and specific ongoing management of the requirement is difficult. Therefore, the analysis and the application of owner's requirements is limited in project process. The purpose of this study is proposed to the RFM technique to supplement the functional analysis on the basis owner's requirements analysis in planning a building project.

• 한국건설관리학회논문집
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• 제7권3호
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• pp.102-111
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• 2006

건설 VE Job plan의 진행단계 중 초기 단계인 기능분석에서 핵심이라 할 수 있는 기능정의의 정확성은 VE 성과와 직결된다. 그러나 현재 사용되고 있는 기능정의의 방법은 정확한 정의와 이해가 이루어지지 않거나 활용방법에 어려움이 따라 체계적으로 수행하지 못하는 경우가 많으며 VE 대상 선정에 있어 기능에 대한 정의가 명확하게 이루어지지 않아 기능정의 후 기능정리 단계에서 각 기능들간의 유기적 연결에 어려움이 발생하는 경우가 많다. 이에 본 연구에서는 기능정의를 보다 명확하게 하여 차후 기능정리에서 발생하는 문제점을 보완하여 보다 나은 기능분석 단계를 유도할 수 있도록 하기 위한 CAFAT(Combined Antithetic Function Analysis Technique)을 제안하고자 한다.

• Structural Engineering and Mechanics
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• 제86권3호
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• pp.349-359
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• 2023

This paper presents a technique for determining the optimal number of elements in stochastic finite element analysis based on reliability analysis. Using the change-of-variable perturbation stochastic finite element approach, the probability density function of the dynamic responses of stochastic structures is explicitly determined. This method combines the perturbation stochastic finite element method with the change-of-variable technique into a united model. To further examine the relationships between the random fields, discretization of the random field parameters, such as the variance function and the scale of fluctuation, is also performed. Accordingly, the reliability index is calculated based on the explicit probability density function of responses with Gaussian or non-Gaussian random fields in any number of elements corresponding to the random field discretization. The numerical examples illustrate the effectiveness of the proposed method for a one-dimensional cantilever reinforced concrete column and a two-dimensional steel plate shear wall. The benefit of this method is that the probability density function of responses can be obtained explicitly without the use simulation techniques. Any type of random variable with any statistical distribution can be incorporated into the calculations, regardless of the restrictions imposed by the type of statistical distribution of random variables. Consequently, this method can be utilized as a suitable guideline for the efficient implementation of stochastic finite element analysis of structures, regardless of the statistical distribution of random variables.