• Title, Summary, Keyword: modulus

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Correlation Analysis between Ultrasonic Parameters and Elastic Modulus of Apple

  • Kim, Ghi-Seok;Kim, Ki-Bok;Park, Jeong-Gil;Lee, Sang-Dae;Jung, Hyun-Mo;Kim, Man-Soo
    • Journal of the Korean Society for Nondestructive Testing
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    • v.28 no.3
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    • pp.279-284
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    • 2008
  • The firmness of fruit is one of the most important quality factors and is highly correlated to the elastic modulus. In this study, the ultrasonic transmission method was applied to evaluate the elastic modulus of the apple. In order to transmit and receive the ultrasonic wave through the whole apple, the ultrasonic measurement setup consisted of ultrasonic pulser, two specially fabricated ultrasonic transducers for fruit and digital storage oscilloscope. Ultrasonic parameters such as ultrasonic wave velocity, apparent attenuation, and peak frequencies were analyzed. The elastic modulus of apple was measured by using compression test apparatus. The correlations between ultrasonic parameters and elastic modulus were analyzed. A multiple linear regression model describing the relationship between elastic modulus and ultrasonic parameters was proposed.

Analytical Approximation of the Relaxation Time Spectrum of Monodisperse Linear Polymer Melts (단분산성 고분자 용융체의 완화시간분포의 해석적인 근사계산법)

  • Choi, Joong Hwan
    • Textile Science and Engineering
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    • v.51 no.4
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    • pp.207-211
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    • 2014
  • The relaxation time spectrum is a versatile parameter to calculate various polymer viscoelastic properties, such as the relaxation modulus (G(t)), dynamic modulus (G'(${\omega}$)) and loss modulus (G"(${\omega}$)). However, it cannot be measured experimentally. This study calculated the relaxation time spectrum using a calculation method based on Fusso-Kirkwood's theoretical research and using the empirical loss modulus formula. The calculated relaxation time spectrum and Rouse's model could describe the viscoelastic behavior of monodisperse polystyrene successfully. This analytical approximation of the relaxation time spectrum differed from experimental data in the intermediate region between the reputation and Rouse region. This may have resulted from a limitation of the molecular theory in the Rouse region.

Nondestructive Bending Strength Evaluation of Ceramics Made from Miscanthus sinensis var. purpurascens Particle Boards - Effect of Resin Impregnation Ratio -

  • Byeon, Hee-Seop;Won, Kyung-Rok;Oh, Seung-Won
    • Journal of the Korean Wood Science and Technology
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    • v.42 no.2
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    • pp.130-137
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    • 2014
  • Nondestructive evaluation (NDE) method by using a resonance frequency mode was carried out for ceramics made from particle boards with different phenol resin impregnation ratios (30, 40, 50, 60%) at carbonizing temperature of $800^{\circ}C$. The material for ceramics was Miscanthus sinensis var. purpurascens board. Dynamic modulus of elasticity increased with increasing impregnation ratio. There was a close relationship of dynamic modulus of elasticity and static bending modulus of elasticity to modulus of rupture (MOR). However, the result indicated that correlation coefficient is higher in dynamic modulus of elasticity to MOR than that in static modulus of elasticity to MOR. Therefore, the dynamic modulus of elasticity using resonance frequency by free vibration mode is more useful as a nondestructive evaluation method for predicting the MOR of ceramics made from Miscanthus sinensis var. purpurascens particle boards by different phenol resin impregnation ratios.

Effects of environmental temperature and age on the elastic modulus of concrete

  • Yang, Shuzhen;Liu, Baodong;Li, Yuzhong;Zhang, Minqiang
    • Structural Engineering and Mechanics
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    • v.72 no.6
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    • pp.737-746
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    • 2019
  • Concrete mechanical properties change constantly with age, temperature, humidity and the other environmental factors. This research studies the effects of temperature and age on the development of concrete elastic modulus by a series of prism specimens. Elastic modulus test was conducted at various temperatures and ages in the laboratory to examine the effects of temperature and age on it. The experimental results reveal that the concrete elastic modulus decreases with the rise of temperature but increases with age. Then, a temperature coefficient K is proposed to describe the effects of temperature and validated by existing studies. Finally, on the basis of K, analytical models are proposed to determine the elastic modulus of concrete at a given temperature and age. The proposed models can offer designers an approach to obtain more accurate properties of concrete structures through the elastic modulus modification based on actual age and temperature, rather than using a value merely based on laboratory testing.

Prediction of tensile modulus in polymer nanocomposites containing carbon nanotubes (CNT) above percolation threshold by modification of conventional model

  • Zare, Yasser;Rhee, Kyong Yop
    • Current Applied Physics
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    • v.17 no.6
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    • pp.873-879
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    • 2017
  • In this paper, a simple model is developed to predict the tensile modulus of polymer/carbon nanotubes (CNT) nanocomposites (PCNT) above percolation threshold. Since the conventional models such as Ouali and Lyngaae-Jorgensen (L-J) cannot predict the accurate results, a developed model is presented which calculates proper modulus as a function of aspect ratio (${\alpha}$) and volume fraction of CNT at percolation threshold (${\phi}_p$). The developed model can present accurate data, which agree with the experimental results at all filler concentrations. The high ranges of "${\alpha}$" and low values of "${\phi}_p$" achieve a desirable modulus. However, a high "${\phi}_p$" causes the poor modulus at different "${\alpha}$" demonstrating that the role of "${\alpha}$" is highlighted at slight "${\phi}_p$". It is also possible to calculate the "${\alpha}$" and "${\phi}_p$" parameters by applying the developed model to the experimental data of modulus.

Performance Analysis of Blind Equalization Algorithms using Multilevel Modulus (다중레벨 Modulus를 사용한 블라인드 등화 알고리즘의 성능 분석)

  • 오길남
    • Proceedings of the IEEK Conference
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    • pp.69-72
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    • 2001
  • 본 논문에서는 디지털 통신 시스템의 블라인드 등화에 있어서, 다중레벨 modulus를 기준 신호로 사용하여 등화기의 탭 계수 갱신 식에 사용되는 오차 신호를 형성함으로써 등화기의 블라인드 수렴 특성을 개선한 다중레벨 modulus 알고리즘들의 성능을 분석하였다. 다중경로 채널 하에서 QAM 신호점에 대해 컴퓨터 모의실험을 통하여 단일/다중레벨 modulus 알고리즘(SMMA)과 기존의 modified constant modulus algorithm(MCMA) 및 최근에 제안된 다중레벨 modulus 알고리즘(MMA) 등의 블라인드 수렴 및 정상 상태 성능을 비교하였다.

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U-FLATNESS AND NON-EXPANSIVE MAPPINGS IN BANACH SPACES

  • Gao, Ji;Saejung, Satit
    • Journal of the Korean Mathematical Society
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    • v.54 no.2
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    • pp.493-506
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    • 2017
  • In this paper, we define the modulus of n-dimensional U-flatness as the determinant of an $(n+1){\times}(n+1)$ matrix. The properties of the modulus are investigated and the relationships between this modulus and other geometric parameters of Banach spaces are studied. Some results on fixed point theory for non-expansive mappings and normal structure in Banach spaces are obtained.

ON THE MAXIMUM AND MINIMUM MODULUS OF POLYNOMIALS ON CIRCLES

  • Chong, Han Kyol;Kim, Seon-Hong
    • Communications of the Korean Mathematical Society
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    • v.33 no.4
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    • pp.1303-1308
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    • 2018
  • In this paper, we consider both maximum modulus and minimum modulus on a circle of some polynomials. These give rise to interesting examples that are about moduli of Chebyshev polynomials and certain sums of polynomials on a circle. Moreover, we obtain some root locations of difference quotients of Chebyshev polynomials.

An Experimental Study on the Elastic Modulus of Deep Mixing Ground Specimen (심층혼합 시료의 탄성계수에 관한 실험적 연구)

  • Park, Choon-Sik;Park, Hwan-Ki
    • Journal of the Korean Geotechnical Society
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    • v.34 no.10
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    • pp.39-49
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    • 2018
  • In this study, aimed at determining the elastic modulus of deep mixed samples, 320 test specimens were developed by mixing 8%, 10%, 12%, and 14% of stabilizer mixture in the granular conditions of clay, sand and gravel. Uniaxial compression tests were carried out using these specimens, and the uniaxial compression strength and strain were analyzed to determine the secant elastic modulus and tangent elastic modulus. Laboratory test results showed that the uniaxial compression strength of all deep mixed samples increased with increasing curing time and stabilizer mixing ratio, and that the secant elastic modulus and the tangen elastic modulus also increased. The increase of the elastic modulus according to the curing period turned out greater in the tangent elastic modulus than in the secant elastic modulus. In order to measure elastic modulus with changes in stabilizer mixing ratio, the correlation coefficient between the elastic modulus for stabilizer mixing ratio of 8% and that of 10%, 12% and 14% was calculated respectively by the specimen condition. The elastic modulus tended to increase as the grain size in a deep mixed specimen increased. The distribution of grain size that had the greatest effect appeared when the composition ratio of sand was high. On the other hand, the increase in the elastic modulus was larger in the sand specimens than in the clay and gravel specimens. Based on these results, it is suggested that a pertinent soil parameter of the deep mixed ground in the field may be obtained by the particle size distribution and the mixing ratio of stabilizer of the deep mixed soil.