• Title, Summary, Keyword: elasticity

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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.

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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    • 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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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.

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.

High-Precision Direct-Operated Relief Valve with a Variable Elasticity Spring (변탄성 스프링을 이용한 고정밀 직동형 릴리프 밸브)

  • Kim, SungDong
    • Journal of Drive and Control
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    • v.17 no.4
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    • pp.87-96
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    • 2020
  • In this study, a variable elasticity spring was applied to improve the pressure control precision of conventional relief valves. The equilibrium equation of the forces acting on the valve poppet was derived; it is demonstrated that matching the elastic rate of the pressure-adjusting coil spring to the equivalent elastic rate of the flow force improved the pressure override. The procedures that were used to design the variable elasticity spring are presented, and some applications of the variable elasticity spring are also introduced. Computer simulations were used to analyze three cases: a poppet-closed flow force structure, a poppet-open flow force structure with a constant elasticity spring, and a structure containing a variable elasticity spring. It is confirmed that the pressure control precision of the relief valve can be significantly improved upon by applying a variable elasticity spring to the poppet-open flow force structure.

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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Elasticity of Demand for Urban Housing in Western China Based on Micro-data - A Case Study of Kunming

  • Zhang, Hong;Li, Shaokai;Kong, Yanhua
    • The Journal of Industrial Distribution & Business
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    • v.7 no.3
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    • pp.27-36
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    • 2016
  • Purpose - Considering the importance of housing needs to real estate market, domestic studies on real estate prices from the perspective of demand are basically based on macro-data, but relatively few are associated with micro-data of urban real estate demand. We try to find a reliable relation of elasticity of demand and commercial housing market. Research design, data, and methodology - In this paper, we have derived housing demand theoretic method and have utilized micro-data of residential family housing survey of downtown area in Kunming City in October, 2015 to estimate income elasticity and price elasticity of housing demand respectively and make a comparative analysis. Results - The results indicate that income elasticity and price elasticity of families with owner-occupied housing are both larger than those of families with rental housing. Income elasticity of housing demand of urban residential families in Kunming is far below the foreign average and eastern coastal cities level, however, the corresponding price elasticity is far higher. Conclusions - We suggest that housing affordability of urban families in western China are constrained by the level of economic development, and the current housing price level has exceeded the economic affordability and psychological expectation of ordinary residents. Furthermore, noticing the great rigidity of housing demand, the expansion space of housing market for improvement and for commodity is limited.

A Experimental Study on Application of KS F 2456 using Shear Wave (급속 동결 융해에 대한 콘크리트의 저항 시험방법(KS F 2456)에 전단파 적용을 위한 실험적 연구)

  • An, Ji-Hwan;Jeon, Sung-Il;Kwon, Soo-Ahn
    • International Journal of Highway Engineering
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    • v.14 no.5
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    • pp.57-65
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    • 2012
  • PURPOSES: It is important to consider the long-term performance of concrete pavement, because concrete pavement is more exposed to the various environmental conditions than any other concrete structures. One of the several methods to evaluate the long-term performance of concrete during winter is KS F 2456. Relative dynamic modulus of elasticity shows the resistance to freezing and thawing. METHODS: To measure relative dynamic modulus of elasticity, ultra sonic is generally used. But in this study, to measure the relative dynamic modulus of elasticity, both ultra sonic and shear wave were used and then compared each other. RESULTS: The results from the measurement by ultrasonic wave and shear wave were divided into three types. Type 1 : Specimens are good and relative dynamic modulus of elasticity did not decrease until 300 cycle. Type 2 : The relative dynamic modulus of elasticity decreased from the late cycle.(about 150 cycle later) Type 3 : The relative dynamic modulus of elasticity consistently decreased from the beginning. As a result of ANOVA, there is no difference according to measuring method, in type 2 and 3. But there is a difference according to measuring method, in type 1's relative dynamic modulus of elasticity. CONCLUSIONS: It is proved that shear wave can be used to understand the damage tendency of relative freezing and thawing and to measure the relative dynamic modulus of elasticity.

A simple and efficient 1-D macroscopic model for shape memory alloys considering ferro-elasticity effect

  • Damanpack, A.R.;Bodaghi, M.;Liao, W.H.;Aghdam, M.M.;Shakeri, M.
    • Smart Structures and Systems
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    • v.16 no.4
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    • pp.641-665
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    • 2015
  • In this paper, a simple and efficient phenomenological macroscopic one-dimensional model is proposed which is able to simulate main features of shape memory alloys (SMAs) particularly ferro-elasticity effect. The constitutive model is developed within the framework of thermodynamics of irreversible processes to simulate the one-dimensional behavior of SMAs under uniaxial simple tension-compression as well as pure torsion+/- loadings. Various functions including linear, cosine and exponential functions are introduced in a unified framework for the martensite transformation kinetics and an analytical description of constitutive equations is presented. The presented model can be used to reproduce primary aspects of SMAs including transformation/orientation of martensite phase, shape memory effect, pseudo-elasticity and in particular ferro-elasticity. Experimental results available in the open literature for uniaxial tension, torsion and bending tests are simulated to validate the present SMA model in capturing the main mechanical characteristics. Due to simplicity and accuracy, it is expected the present SMA model will be instrumental toward an accurate analysis of SMA components in various engineering structures particularly when the ferro-elasticity is obvious.

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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    • 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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