• 대한조선학회논문집
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• 제52권4호
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• pp.315-322
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• 2015

In this paper, the theory of rectangular plate on the elastic foundation is used to get the relation equation between the effective Young’s modulus and the ice sheet deflection by applying the characteristic length concept, since the model ice sheet is rectangular shape in KRISO (Korea Research Institute for Ships and Ocean Engineering) ice basin. The obtained relation equation is equal to that of using the circular plate theory. A device is made and used to measure the deflection of ice plate using LVDT (Linear Variable Differential Transformer) for several loading cases and the procedure of experiments measuring the deflection used for getting the Young’s modulus is explained. In addition, the flexural strength value obtained through flexural strength experiments is compared with that of finite element analysis using the obtained effective Young’s modulus. Also, a nonlinear FEA (Finite Element Analysis) of cantilever ice beam is done with eroding effect and LS-DYNA result shows the fracture of brittle ice under 1 mm/s velocity load.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1368-1372
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• 2003

PMMA which is used as the bone cement for vertebroplasty is able to be a supporter, as a fixing supporter role, for broken trabecular structure, caused by the compressed fracture of spine on aged osteoporosis. In this thesis, as experimenting apparent density of bone pieces, we have figured out support extent of Young's modulus as classifying the bone pieces injected PMMA and the others which are not. In case of low apparent density of PMMA in some bone, Young's modulus seems to be more supportable to bone. On the other hand, if apparent density of bones is normal, injection of PMMA is not very effective on improvement in Young's modulus of bone cement injection.

• 대한의용생체공학회:의공학회지
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• 제31권3호
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• pp.194-198
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• 2010

The effective Young’s modulus of a microfibril surrounded by water may be simply calculated by using the upper (Voigt) and lower (Reuss) bounds, which is one way to estimate the Young’s modulus in composite materials. The Steered Molecular Dynamics (SMD) has been used for estimating the Young’s modulus of a microfibril surrounded by water. In this paper, the result estimated by the upper (Voigt) and lower (Reuss) bounds shows 9.2% to 21.8% discrepancy from the result estimated by SMD, but introducing “efficiency of reinforcement parameter” removes the discrepancy and shows good agreement with the result estimated by SMD. We found the best fit for the Young’s modulus against the size of the gap between microfibrils. Also the steps using these bounds are much simpler than SMD.

• Carbon letters
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• 제11권4호
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• pp.325-331
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• 2010

This study investigates the effect of filler content (wt%), presence of interphase and agglomerates on the effective Young's modulus of polypropylene (PP) based nanocomposites reinforced with exfoliated graphite nanoplatelets ($xGnP^{TM}$) and carbon nanotubes (CNTs). The Young's modulus of the composites is determined using tensile testing based on ASTM D638. The reinforcement/polymer interphase is characterized in terms of width and mechanical properties using atomic force microscopy which is also used to investigate the presence and size of agglomerates. It is found that the interphase has an average width of ~30 nm and modulus in the range of 5 to 12 GPa. The Halpin-Tsai micromechanical model is modified to account for the effect of interphase and filler agglomerates and the model predictions for the effective modulus of the composites are compared to the experimental data. The presented results highlight the need of considering various experimentally observed filler characteristics such as agglomerate size and aspect ratio and presence and properties of interphase in the micromechanical models in order to develop better design tools to fabricate multifunctional polymer nanocomposites with engineered properties.

• Smart Structures and Systems
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• 제29권3호
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• pp.387-393
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• 2022

This paper presents the vibration analysis of cracked ceramic-reinforced aluminum composite beams by using a method based on changes in modal strain energy. The crack is considered to be straight. The effective properties of composite materials of the beams are estimated through Mori-Tanaka micromechanical model. Comparison study and numerical simulations with various parameters; ceramic volume fraction, reinforcement aspect ratio, ratio of the reinforcement Young's modulus to the matrix Young's modulus and ratio of the reinforcement density to the matrix density are taken into investigation. Results demonstrate the pronounced effects of these parameters on intact and cracked ceramic aluminum beams.

• 한국지열·수열에너지학회논문집
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• 제17권4호
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• pp.15-27
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• 2021

In this study, the effect of design factors in a pump station on the pressure variations which are the main cause of water hammering has been investigated by numerical simulations. As design factors, the flow rate, Young's modulus, diameter, thickness, roughness coefficient of pipeline are considered. The relationships between the pressure variations and the design factors are analyzed. The results show that the pressure variation increases sensitively with the flow rate and Young's modulus, and increases gradually with the thickness and roughness coefficient of pipe, whereas it decreases with the pipe diameter. The wavelength of the pressure wave becomes longer for a smaller Young's modulus, a smaller pipe thickness and a bigger pipe diameter. These relationships are nondimensionalized, and logarithmic curve-fitted functions are proposed by regression analysis. Most effective factors on the nondimensional pressure variation is Young's modulus. Flow rate, roughness coefficient, relative thickness and pipe diameters are the next impact factors.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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• pp.150-152
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• 2007

It has been known that the underfilling technique is effective in reducing thermal and environmental stress concentration at solder joint in FC asscemblies. In this paper, the effect of thermomechanical properties of underfill such as coefficient of thermal expansion(CTE) and Young's modulus on reliability of FC assembly under thermal cycling was investigated. For parametric study for optimal design of underfill, finite element analyses(FEA) were performed for seven different CTEs and five different Young's modulus. The results show that the concentrated maximum stress decreases as Young's modulus of underfill increases and the CTE of underfill decreases.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.805-814
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• 2008

This study focused on the resilient modulus prediction model, which is the functions of mean effective principal stress and axial strain, for three types of railroad trackbed materials such as crushed stone, weathered soil, and crushed-rock soil mixture. The model is composed with the maximum Young's modulus and nonlinear values for higher strain in parallel with dynamic shear modulus. The maximum values is modeled by model parameters, $A_E$ and the power of mean effective principal stress, $n_E$. The nonlinear portion is represented by modified hyperbolic model, with the model parameters of reference strain, ${\varepsilon}_r$ and curvature coefficient, a. To assess the performance of the prediction models proposed herein, the elastic response of a test trackbed near PyeongTaek, Korea was evaluated using a 3-D nonlinear elastic computer program (GEOTRACK) and compared with measured elastic vertical displacement during the passages of freight and passenger trains. The material types of sub-ballasts are crushed stone and weathered granite soil, respectively. The calculated vertical displacements within the sub-ballasts are within the order of 0.6mm, and agree well with measured values with the reasonable margin. The prediction models are thus concluded to work properly in the preliminary investigation.

• Advances in Computational Design
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• 제9권1호
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• pp.53-71
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• 2024

Owing to these mechanical properties, carbon nanotubes have the potential to be employed in many future devices and nanostructured materials. As an example, high Young modulus accompanied by their low density, makes them a good choice for reinforcing material in composites. Therefore, we empathize and manually derive the results which shows the utilized lemma and criterion are believed effective and efficient for aircraft structural analysis of composite and nonlinear scenarios. To be fair, the experiment by numerical computation and calculations were explained the perfectness of the methodology we provided in the research.

• Nuclear Engineering and Technology
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• 제44권5호
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• pp.501-506
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• 2012

Many innovative design features are employed in the reactor vessel internals of SMART, a small integral-type pressurized water reactor, one of which is the flow skirt, which uniformly distributes flow and horizontally restrains the lower part of the core support barrel. This new design requires a comprehensive investigation of vibration characteristics. Therefore, in this study, modal characteristics of flow skirts are investigated with finite element analysis. Specifically, we investigate how the presence of holes, the presence of three rings attached to the flow skirt, and the thickness of the lowest shell effect vibration characteristics. In addition, the fluid effect is addressed, since the flow skirt is submerged in the fluid.