• Title/Summary/Keyword: Elasticity Analysis

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A Study on the Analysis and Measurement for the Elasticity of the Catenary System (전차선로 탄성도 해석 및 측정에 관한 연구)

  • 조용현;최강윤;조기조;권삼영
    • Proceedings of the KSR Conference
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    • 2002.10b
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    • pp.1100-1105
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    • 2002
  • The elasticity of the contact wire is one of important static parameters for the catenary system. This paper presents how to analyse the elasticity of the catenary system using both simple string model method and finite element method with their formula. Analysis results obtained by these two methods for KTX catenary system are compared. A measurement of the elasticity for the KTX catenary under construction which is located near Kumkang bridge is made for the comparison with the analysis results. Both a dynamic and a static methods are tried for the measurement. Because of wave propagation, the dynamic method with 5 km/h running presented an asymmetric variational pattern of the elasticity while the static method presented a symmetric pattern of the elasticity in the span. Measured elasticity using the static method is found to be a little higher than the analysis results. But, the static method can presented us a variational pattern of the elasticity in the span similar to the analysed results. Therefore, the static method can be used for evaluating the elasticity of the catenary system

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Evaluation of the Usefulness of Differential Diagnosis of Breast Mass using Elasticity Score and Elasticity Ratio in Elastography (탄성초음파에서 유방종괴의 감별진단을 위한 탄성도 점수와 변형비의 유용성 평가)

  • An, Hyun;Im, In-Chul;Lee, Hyo-Yeong
    • Journal of the Korean Society of Radiology
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    • v.12 no.5
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    • pp.677-682
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    • 2018
  • This study evaluated the usefulness of the elasticity score and elasticity ratio in the differential diagnosis of benign and malignant lesion in breast elastography. We performed a retrospective analysis based on the results of core needle biopsy histology. The Mann-Whitney U test was used to confirm the difference between the 5-degree elasticity score and the Fisher's Exact test. ROC curve analysis was used to determine the elasticity score and the best cut-off value of the elasticity ratio for the prediction of malignant lesions. There was a statistically significant difference (p= .000) between the homogeneity of the elasticity score and the difference of the elasticity ratio between the benign and malignant lesion groups. On the ROC curve analysis, the elasticity score and the elasticity ratio for predicting benign and malignant lesion were determined as AUC 0.806, 0.824, cut-off value 3, 4.4 (p= .001). Therefore, the elasticity score and elasticity ratio may be useful in the differential diagnosis of breast mass.

Weak forms of generalized governing equations in theory of elasticity

  • Shi, G.;Tang, L.
    • Interaction and multiscale mechanics
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    • v.1 no.3
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    • pp.329-337
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    • 2008
  • This paper presents the derivation of the generalized governing equations in theory of elasticity, their weak forms and the some applications in the numerical analysis of structural mechanics. Unlike the differential equations in classical elasticity theory, the generalized equations of the equilibrium and compatibility equations presented here take the form of integral equations, and the generalized equilibrium equations contain the classical differential equations and the boundary conditions in a single equation. By using appropriate test functions, the weak forms of these generalized governing equations can be established. It can be shown that various variational principles in structural analysis are merely the special cases of these weak forms of generalized governing equations in elasticity. The present weak forms of elasticity equations extend greatly the choices of the trial functions for approximate solutions in the numerical analysis of various engineering problems. Therefore, the weak forms of generalized governing equations in elasticity provide a powerful modeling tool in the computational structural mechanics.

Price Elasticity Analysis of University Students in Foodservice Operations for Pricing Policy (대학교 학생식당의 가격정책을 위한 가격탄력성 분석)

  • 양일선;백승희;신서영
    • Korean Journal of Community Nutrition
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    • v.4 no.4
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    • pp.587-593
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    • 1999
  • The purpose of this study were to : (a) analyzed price elasticity of university students in foodservice operations and (b)provide insight for price decision-making. Questionnaires were composed of price elasticity, the utilization and opinions of students on university foodservice operations, and demographic information regarding respondents. The questionnaires were distributed to 600 university students of 6 universities located in Seoul. Statistical data analysis was completed using the SAS package for descriptive analysis, t-test, ANOVA, and Pearson’s correlation. The results of this study can be summarized as follows: The average price for lunch was ₩1,663 for campus food, and ₩2,965 for off-campus restaurants. The frequency of utilizing the university cafeteria was fairly high. Students felt that the proper price for lunch was ₩1,446, presenting a lower price than the actual average price for lunch. The price elasticity was investigated in relation to the change in utilization rate when these was a price increase. The price elasticity was 2.03, with significant differences between sex, age, and major. The groups utilizing the university cafeteria frequently, taking longer time to go to off-campus or that were satisfied with the university cafeteria, had a lower price elasticity than those that did not. The results of this study suggest that predicting the price elasticity of the target market would assist the pricing policy, and the fact that the same students have different price elasticity by place and atmosphere can be used in marketing strategies.

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An asymptotic multi-scale approach for beams via strain gradient elasticity: surface effects

  • Kim, Jun-Sik
    • Multiscale and Multiphysics Mechanics
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    • v.1 no.1
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    • pp.15-33
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    • 2016
  • In this paper, an asymptotic method is employed to formulate nano- or micro-beams based on strain gradient elasticity. Although a basic theory for the strain gradient elasticity has been well established in literature, a systematic approach is relatively rare because of its complexity and ambiguity of higher-order elasticity coefficients. In order to systematically identify the strain gradient effect, an asymptotic approach is adopted by introducing the small parameter which represents the beam geometric slenderness and/or the internal atomistic characteristic. The approach allows us to systematically split the two-dimensional strain gradient elasticity into the microscopic one-dimensional through-the-thickness analysis and the macroscopic one-dimensional beam analysis. The first-order beam problem turns out to be different from the classical elasticity in terms of the bending stiffness, which comes from the through-the-thickness strain gradient effect. This subsequently affects the second-order transverse shear stress in which the surface shear stress exists. It is demonstrated that a careful derivation of a first strain gradient elasticity embraces "Gurtin-Murdoch traction" as the surface effect of a one-dimensional Euler-Bernoulli-like beam model.

A Study on the Elasticity Disuniformity for Catenary using by Beam Model (빔 모델을 이용한 전차선 불균일율에 관한 연구)

  • 권삼영;이기원;조용현;정흥채
    • Proceedings of the KSR Conference
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    • 1999.11a
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    • pp.209-217
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    • 1999
  • A catenary system should be designed to be an uniform elasticity over a span in order to maintain the lowest possible loss of contact between a pantograph and a contact wire. A elasticity disuniformity of a catenary can be regarded as a important design factor used for predicting the current collection performance for a catenary. There are a couple of formulas to calculate elasticity disuniformity of a catenary according to the literature survey, The effectiveness of these formulas is reviewed by performing catenary elasticity and loss of contact analysis for 5 different configurations of catenary systems using a beam element based FEM program, KRRI developed program, and the loss of contact by GASENDO, RTRI developed program, respective]y. The results reveals that these formulas are not suitable to predict the current collection performance for a catenary. Therefore, a new formula based on the standard deviation of the elasticity over a span is proposed in this study. The analysis results show that the new formula for an elasticity disuniformity of a catenary is very effective in predicting the current collection performance for a catenary.

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Analysis of Future Trends for Refractory Dissolved Organic Carbon in the Nakdong River Basin using Elasticity Theory (탄성도 이론을 이용한 낙동강유역 난분해성 용존 유기탄소 미래 추세 분석)

  • Park, Yoonkyung;Choi, Daegyu;Lee, Jae Woon;Kang, Limseok;Kim, Sangdan
    • Journal of Korean Society on Water Environment
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    • v.29 no.4
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    • pp.476-488
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    • 2013
  • Refractory Dissolved Organic Carbon (RDOC) is becoming more important index on management of water quality, water regulation as well as ecosystem management. We analyzed trends of RDOC using elasticity in the Nakdong river basin. If climate elasticity of streamflow is positive, change of streamflow can be defined by the proportional change in a climatic variable such as precipitation and temperature. Elasticity of streamflow to precipitation and elasticity of RDOC to precipitation were estimated in the present, and we also analyzed the variation of elasticity in the future using climate change scenarios, RCP 8.5/ 4.5. Mean streamflow elasticity is 1.655, and mean RDOC elasticity is 1.983. RDOC is more sensitive to precipitation change than streamflow. The variation of RDOC is directly proportion to precipitation in all scenarios, but the Load of RDOC is dependent on precipitation as well as others. There is a need for additional correlation analysis between RDOC and other factors for accurate prediction.

Nonlocal integral elasticity analysis of beam bending by using finite element method

  • Taghizadeh, M.;Ovesy, H.R.;Ghannadpour, S.A.M.
    • Structural Engineering and Mechanics
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    • v.54 no.4
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    • pp.755-769
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    • 2015
  • In this study, a 2-D finite element formulation in the frame of nonlocal integral elasticity is presented. Subsequently, the bending problem of a nanobeam under different types of loadings and boundary conditions is solved based on classical beam theory and also 3-D elasticity theory using nonlocal finite elements (NL-FEM). The obtained results are compared with the analytical and numerical results of nonlocal differential elasticity. It is concluded that the classical beam theory and the nonlocal differential elasticity can separately lead to significant errors for the problem under consideration as distinct from 3-D elasticity and nonlocal integral elasticity respectively.

FREE VIBRATION ANALYSIS OF PERFORATED PLATE WITH SQUARE PENETRATION PATTERN USING EQUIVALENT MATERIAL PROPERTIES

  • JHUNG, MYUNG JO;JEONG, KYEONG HOON
    • Nuclear Engineering and Technology
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    • v.47 no.4
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    • pp.500-511
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    • 2015
  • In this study, the natural frequencies of the perforated square plate with a square penetration pattern are obtained as a function of ligament efficiency using the commercial finite-element analysis code ANSYS. In addition, they are used to extract the effective modulus of elasticity under an assumption of a constant Poisson's ratio. The effective modulus of elasticity of the fully perforated square plate is applied to the modal analysis of a partially perforated square plate using a homogeneous finite-element analysis model. The natural frequencies and the corresponding mode shapes of the homogeneous model are compared with the results of the detailed finite-element analysis model of the partially perforated square plate to check the validity of the effective modulus of elasticity. In addition, the theoretical method to calculate the natural frequencies of a partially perforated square plate with fixed edges is suggested according to the Rayleigh-Ritz method.

Analysis of Air-water Temperature Elasticity Taking into Account the Confidence Interval in Major Tributary of Nakdong River (낙동강 주요 지류의 신뢰구간을 고려한 기온-수온 탄성도 분석)

  • Park, Jaebeom;Kal, Byungseok;Kim, Seongmin
    • Journal of Wetlands Research
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    • v.22 no.3
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    • pp.178-186
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    • 2020
  • In this study, the elasticity was calculated and sensitivity analysis was performed using air-water temperature data of the major tributaries of the Nakdong River. We developed a nonparametric elasticity analysis technique capable of estimating the confidence interval for elasticity and verifying the hypothesis, and examined its applicability compared to the existing method using the median value. It is analyzed that the elasticity of winter is low and the elasticity of summer and autumn is high, so that the fluctuation of water temperature and water quality according to the fluctuation of air temperature is large. The spatial elasticity tends to be low in the Geumho River area, which is influenced by artificial factors such as sewage treatment plant effluent, small and medium-sized livestock wastewater, and small-scale factory wastewater. Since the elasticity of major tributaries of the Nakdong River is over weak and is reasonable at a significance level of 5%, it was analyzed that the air-water temperature fluctuation caused by climate changes is large.