• Journal of Biomedical Engineering Research
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• v.24 no.4
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• pp.369-373
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• 2003

The compressed fracture of spine caused by osteoporosis is one of the most frequent diseases in bone fracture. Recently the vertebroplasty has drawn much attention as a medical treatment for the compressed fracture of spine, which strengthens the vertebral body and corrects deformity, and relieves pain in patients by injecting bone cement. But because there were no research about strengthening of mechanical properties of verbral body in bone cement injection, in this study, based on the properties of PMMA, we had measured the Young's modulus for different apparent densities of intact trabecular bone and PMMA injected one from a porcine and a cadaver. Young's modulus to apparent density had a form of a power series in intact trabecular bone and had a linear relation in PMMA injected bone.

• Nuclear Engineering and Technology
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• v.54 no.7
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• pp.2359-2366
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• 2022

Selecting graphite grades with superior irradiation characteristics is important task for designers of graphite moderation reactors. To provide reference information and data for graphite selection, the effects of irradiation on three fine-grained, iso-molded nuclear grade graphites, ETU-10, IG-110, and NBG-25, were compared based on irradiation-induced changes in volume, thermal conductivity, dynamic Young's modulus, and coefficient of thermal expansion. Data employed in this study were obtained from reported irradiation test results in the high flux isotope reactor (HFIR)(ORNL) (ETU-10, IG-110) and high flux reactor (HFR)(NRL) (IG-110, NBG-25). Comparisons were made based on the irradiation dose and irradiation temperature. Overall, the three grades showed similar irradiation-induced property change behaviors, which followed the historic data. More or less grade-sensitive behaviors were observed for the changes in volume and thermal conductivity, and, in contrast, grade-insensitive behaviors were observed for dynamic Young's modulus and coefficient of thermal expansion changes. The ETU-10 of the smallest grain size appeared to show a relatively smaller VC to IG-110 and NBG-25. Drastic decrease in the difference in thermal conductivity was observed for ETU-10 and IG-110 after irradiation. The similar irradiation-induced properties changing behaviors observed in this study especially in the DYM and CTE may be attributed to the assumed similar microstructures that evolved from the similar size coke particles and the same forming method.

• Geomechanics and Engineering
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• v.34 no.5
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• pp.507-527
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• 2023

Accurately estimation of the geo-mechanical parameters in Artificial Ground Freezing (AGF) is a most important scientific topic in soil improvement and geotechnical engineering. In order for this, one way is using classical and conventional constitutive models based on different theories like critical state theory, Hooke's law, and so on, which are time-consuming, costly, and troublous. The others are the application of artificial intelligence (AI) techniques to predict considered parameters and behaviors accurately. This study presents a comprehensive data-mining-based model for predicting the Young's Modulus of frozen sand under the triaxial test. For this aim, several single and hybrid models were considered including additive regression, bagging, M5-Rules, M5P, random forests (RF), support vector regression (SVR), locally weighted linear (LWL), gaussian process regression (GPR), and multi-layered perceptron neural network (MLP). In the present study, cell pressure, strain rate, temperature, time, and strain were considered as the input variables, where the Young's Modulus was recognized as target. The results showed that all selected single and hybrid predicting models have acceptable agreement with measured experimental results. Especially, hybrid Additive Regression-Gaussian Process Regression and Bagging-Gaussian Process Regression have the best accuracy based on Model performance assessment criteria.

• Journal of Animal Reproduction and Biotechnology
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• v.38 no.3
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• pp.121-130
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• 2023

Background: Coating a culture plate with molecules that aid in cell adhesion is a technique widely used to produce animal cell cultures. Extracellular matrix (ECM) is known for its efficiency in promoting adhesion, survival, and proliferation of adherent cells. Gelatin, a cost-effective type of ECM, is widely used in animal cell cultures including feeder-free embryonic stem (ES) cells. However, the optimal concentration of gelatin is a point of debate among researchers, with no studies having established the optimal gelatin concentration. Methods: In this study, we coated plastic plates with gelatin in a concentration-dependent manner and assessed Young's modulus using atomic force microscopy (AFM) to investigate the microstructure of the surface of each plastic plate. The adhesion, proliferation, and differentiation of the ESCs were compared and analyzed revealing differences in surface microstructure dependent on coating concentration. Results: According to AFM analysis, there was a clear difference in the microstructure of the surface according to the presence or absence of the gelatin coating, and it was confirmed that there was no difference at a concentration of 0.5% or more. ES cell also confirmed the difference in cell adhesion, proliferation, and differentiation according to the presence or absence of gelatin coating, and also it showed no difference over the concentration of 0.5%. Conclusions: The optimum gelatin-coating for the maintenance and differentiation of ES cells is 0.5%, and the gelatin concentration-mediated microenvironment and ES cell signaling are closely correlated.

• Journal of the Korean Society of Hazard Mitigation
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• v.3 no.4 s.11
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• pp.103-109
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• 2003

A numerical analysis of cable-stayed bridge is conducted to determine optimum longitudinal modulus of elasticity which represents the boundary condition between the tower and main girder. The effect of longitudinal modulus of elasticity is investigated for different loading condition (live load, wind load, seismic load), respectively. There are significant changes in the member forces as variations of longitudinal modulus of elasticity, such as, $k_h$=e=100tonf/m/bearing (live load), $k_h$=e=1000tonf/m/bearing (seismic load), However, the wind loads do not affect member forces. The optimum longitudinal modulus of elasticity is determined from considering minimum member forces in the numerical analysis results.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1042-1049
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• 2007

Recently, a theoretically-sound design approach, using an elastic multilayer model, is attempted in trackbed designs for the construction of high speed railways and new lines of conventional railways. In the elastic multilayer model, the stress-dependent resilient modulus($E_R$) is an important input parameter, that is, reflects substructure performance under repeated traffic loading. However, the evaluation method for resilient modulus using repeated loading triaxial test is not fully developed for practical purpose, because of costly equipment and the significantly fluctuated values depending on the testing equipment and laboratory personnel. In this study, the paper will present an indirect method to estimate the resilient modulus using dynamic properties. The resilient modulus of crushed stone, which is the typical material of sub-ballast, was calculated with the measured dynamic properties and the range of stress level of the sub-ballast, and approximated with the power model combined with bulk and deviatoric stresses. The resilient modulus of coarse grained material decreases with increasing deviatoric stress at a confining pressure, and increases with increasing bulk stress. Sandy soil(SM classified from Unified Soil Classification System) of subgrade was also evaluated and best fitted with the power model of deviatoric stress only.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.101-110
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• 2002

This article summarises the traditional method of soil-structure interaction based on the modulus of subgrade reaction and shows its weakness. In order to avoid these weakness, a new soil-structure interaction model is proposed. This model considers the soil as a set of connected springs which enables interaction between springs. Its use is as simple as the traditional model but allows to define the soil properties independently from the structural properties and the loading conditions. Thus, the definition of the modulus of subgrade reaction is unnecessary as each component is defined by its own modulii (Young's modulus and shear modulus). The non-linear soil behaviour for the shear stress versus distortion is also incorporated in the model. This feature allows to pinpoint the arching effect in the ground and shows how the stresses concentrate on stiff materials. Based on these principles, three dimensional program has been developed in order to solve the difficult problem of soil improvement by inclusions (stiff or soft). Also the possibility to take into account a flexible mat and/or a subgrade layer has been implemented. Equations used in the model are developed and a parametric study of the necessary data used in the program is presented. In particular, the Westergaard modulus notion and the arching effect are analysed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.4
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• pp.343-348
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• 2009

In this study, an efficient sequential bridging method to characterize both the particle size effect and concentration effect on the mechanical properties of nanocomposites at high volume fraction is suggested through a molecular dynamics(MD) simulations and micromechanics of composites materials. The Young's modulus and the shear modulus of the nanocomposites at various particle radius and at 12% volume fraction were obtained from MD simulations and multi-inclusion model was adopted to describe both modulus in continuum model. In order to describe the particle size effect, an additional phase, effective interface, was adopted as characteristic phase and the non-dilute concentration effect which appears at 12% volume fraction was describe via the variation of the elastic modulus of the infinite medium. Both the elastic modulus of the interface and infinite medium were fitted into functions of particle radius for the applicability of the present bridging method at various particle radii. Using the present bridging method the elastic modulus of the nanocomposites was efficiently obtained with accuracy. In addition, the effect of the interface thickness and modulus on the elastic modulus of the nanocomposite was investigated.

• Textile Coloration and Finishing
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• v.27 no.3
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• pp.165-174
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• 2015

To develop automobile parts, the unsaturated polyester based matrix resin(PR)/reinforcement(randomly oriented chopped E-glass fiber, GF) composites were prepared using sheet molding compound(SMC) compression molding. The effects of GF length(0.5, 1.0 1.5 and 2.0inch)/content (15, 20, 25, 30wt%) and number of ply(3, 4 and 5) on the specific gravity and mechanical properties of PR/GF composites were investigated in this study. The optimum length of GF was found to be about 1.0inch for achieving improved mechanical properties(tensile strength and initial modulus). The tensile strength and initial modulus of composites increased with increasing GF content up to 30wt%, which is favorable content range for SMC. The specific gravity, tensile strength/initial modulus, compressive strength/modulus, flexural strength/modulus and shear strength increased with increasing the number of ply up to 5, which is the maximum number of ply range for SMC. The effectiveness of ply number increased in the flexural strength > shear strength > compressive strength > tensile strength.

• Journal of the Korean Wood Science and Technology
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• v.11 no.3
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• pp.3-13
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• 1983

Fiber mats were made at five density levels, using fibers from kraft pulp screening rejects, rice straw and a 50/50 mixture of the two. They were soaked in the sulfur compounds. Specimens cut from the composite panels were tested in flexure at time intervals for one year to study the effect of aging. Modulus of elasticity (MOE) and modulus of rupture (MOR) were determined. Under optimum conditions of fiber mat preparation and saturation with molten sulfur and modified sulfur, composites were produced which exhibited mechanical properties comparable to conventional fiberglass in some properties and superior to conventional wood-based composition boards, For example. the moduli of elasticity of the reinforced composites made from pulp screening rejects, with a density of 0.35 gm/$cm^3$, were greater than 1,000,000 psi as compared 800.000 psi for high-density hardboard (1.28 gm/$cm^3$). Modulus of rupture of the best reinforced composites was about 7,000 psi, comparable to 6,000 psi of high-density hardboard.