• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.4
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• pp.34-40
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• 2019

We performed shape optimization of an anti-vibration rubber assembly which is used in the field option cabin of agricultural tractors to improve the vibration isolation capability. To characterize the hyper-elastic material property of rubber, we performed uniaxial and biaxial tension tests and used the data to calibrate the material model applied in the finite element analyses. We conducted a field test to characterize the input excitation from the tractor and the output response at the cabin frame. To account for the nonlinear behavior of rubber, we performed static analyses to derive the load-displacement curve of the anti-vibration rubber assembly. The stiffness of the rubber assembly could be calculated from this curve and was input to the harmonic analyses of the cabin. We compared the results with the test data for verification. We utilized Taguchi's parameter design method to determine the optimal shape of the anti-vibration rubber assembly and found two distinct shapes with reduced stiffness. Results show that the vibration at the cabin frame was reduced by approximately 35% or 47.6% compared with the initial design using the two optimized models.

• Geomechanics and Engineering
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• v.29 no.1
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• pp.53-63
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• 2022

Simplified analytical solutions are developed for the dynamic analyses of an axially loaded pile foundation embedded in a transverse-isotropic, fluid-filled, poro-visco-elastic soil with rigid substratum. The pile is modeled as a viscoelastic Rayleigh-Love rod, while the surrounding soil is regarded as a transversely isotropic, liquid-saturated, viscoelastic, porous medium of which the mechanical behavior is represented by the Boer's poroelastic media model and the fractional derivative model. Upon the separation of variables, the frequency-domain responses for the impedance function of the pile top, and the vertical displacement and the axial force along the pile shaft are gained. Then by virtue of the convolution theorem and the inverse Fourier transform, the time-domain velocity response of the pile head is derived. The presented solutions are validated, compared to the existing solution, the finite element model (FEM) results, and the field test data. Parametric analyses are made to show the effect of the soil anisotropy and the excitation frequency on the pile-soil dynamic responses.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.2 s.173
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• pp.378-385
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• 2000

Fracture resistance (J-R) curves, which are used for elastic-plastic fracture mechanics analyses, decreased under tension-compression loading condition. This phenomenon was proved by several former researches, but the causes have not been clear yet. The objective of this paper is to investigate the cause of this phenomenon. On the basis of fracture resistance curve test results, strain hardening hypothesis, stress redistribution hypothesis and crack opening hypothesis were built. In this study, hardness tests, Automated Ball Indentation(ABI) tests, theoretical stress field analyses, and crack opening analyses were performed to prove the hypotheses. From this study, strain-hardening of material, generation of tensile residual stress at crack tip, and crack opening effects are proved as the causes of the decrease hypothesis.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.759-764
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• 2010

In this study, from the comparison of the results obtained by 3 dimensional dynamic analyses using the inverse-calculated properties and those by calculating using the real earthquake records, the inverse calculation method for obtaining the dynamic properties of rockfill materials was verified. The fundamental frequency of the dam was determined by analyzing the response spectrum of observed records. By repeated dynamic analyses for various shear moduli of rockfill material, the shear moduli in the rockfill zone that satisfy the relationship between the fundamental frequency obtained by analysis of the observed records and that by numerical analyses were determined. Using the determined shear moduli, the 3 dimensional dynamic analyses for the dam were carried out and the result were compared with the real response characteristics on the crest of the dam.

• Journal of the Korean Society of Costume
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• v.58 no.5
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• pp.211-231
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• 2008

To conserve historic textiles, analyses of textile materials, pollutants and deterioration are prerequisite steps. Based upon analytical results, guides for conservation of historic textiles are established. In analyses of textile materials, pollutants and deterioration, there are chemical methods(burning, solubility and staining), physical methods(microscopy and density) and instrumental analysis(Fourier Transform Infrared Spectroscopy (FT-IR), Fourier Transform Raman Spectroscopy(FT-Raman), Gas Chromatography(GC), Mass Spectroscopy(MS), X-Ray Fluorescence (EDXRF, WDXRF), Energy Dispersive Spectroscopy(EDS), and X-Ray Diffraction(XRD), Tensile Testing Machine etc.). Combination of qualitative and quantitative analyses makes accurate diagnosis of textile condition possible. As examples of analyses and conservation of historic textiles, Chuninsan(19 century) similar to sunshade with handing down historic textile and golden decorative skirt(17 century) with excavated costume are taken.

• Structural Engineering and Mechanics
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• v.32 no.6
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• pp.811-833
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• 2009

In the present article bending, buckling and vibration analyses of tapered beams using Eringen non-local elasticity theory are being carried out. The associated governing differential equations are solved employing Rayleigh-Ritz method. Both Euler-Bernoulli and Timoshenko beam theories are considered in the analyses. Present results are in good agreement with those reported in literature. Beam material is considered to be made up of functionally graded materials (fgms). Non-local analyses for tapered beam with simply supported - simply supported, clamped - simply supported and clamped - free boundary conditions are carried out and discussed. Further, effect of length to height ratio on maximum deflections, vibration frequencies and critical buckling loads are studied.

• Journal of Ocean Engineering and Technology
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• v.13 no.1 s.31
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• pp.94-104
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• 1999

In order to evaluate the performance of axially of laterally loaded piles experimentaly, pile load tests can be carried out at the site Otherwise stress analyses or subgrade reaction analyses can solve the problem. In this study, stress analysis using FLAC code and subgrade reaction analyses using load transfer curves recommended by API(1993) were performed consistently on the basis of a result of site investigations, and the result of analyses was compared with the measured. As a result the behavior of pile heads was analyzed accurately for both axially and laterally loaded tests. Furthermore axially transferred loads were calculated appropriately for the measured and axial loads were transferred mainly mainly by the frictional resistance rather than by the tip resistance. Consequently, it can be commented that both analysis methods of soil-pile systems are applicable at teh objective site and that solutions may be more accurate if material properties from the site investigation are more explicit.

• Earthquakes and Structures
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• v.8 no.1
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• pp.133-152
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• 2015

This paper investigates the soil effect on seismic behaviour of reinforced concrete (RC) buildings by using the spread plastic hinge model which includes material and geometric nonlinearity of the structural members. Therefore, typical reinforced concrete frame buildings are selected and nonlinear dynamic time history analyses and pushover analyses are performed. Three earthquake acceleration records are selected for nonlinear dynamic time history analyses. These records are adjusted to be compatible with the design spectrum defined in Turkish Seismic Code. Interstory drifts and damages of selected buildings are compared according to local soil classes. Also, capacity curves of these buildings are compared with maximum responses obtained from nonlinear dynamic time history analyses. The results show that, soil class influences the seismic behaviour of reinforced concrete buildings, significantly.

• Journal of the Korean Ceramic Society
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• v.44 no.2 s.297
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• pp.71-78
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• 2007

A [TEACOOH]-Montmorillonite intercalations complex obtained from Na-Montmorillonite and 10-Carboxy-n-triethylammonium bromide was used to attempt the polymerization of ${\varepsilon}$-caprolactone between the layer spaces of the intercalations complex to achieve Montmorillonite-Polycaprolactone nanocomposites in which the inorganic material (montmorillonite) is chemically combined with the organic polymer (polycaprolactone). The results of X-ray-, IR-, and TEM-analyses for samples obtained after polymerization showed that a polycondensation reaction was successfully produced. For a more precise investigation of the polymeric reaction products the polymerized products were separated from the silicate layers and analyzed with an IR-spectrometer. A comparison of the results of the IR-analyses of the separated polymer with that of the polymer synthesized by the reaction of ${\varepsilon}$-caprolactone with only the organic cation and without montmorillonite showed that the two obtained polymers are the same compound.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.1
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• pp.59-65
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• 2013

The objective of this paper is to analyze the structure of the wind power tree using a helical type wind turbine. The blades of a helical rotor is designed with a composite material. The structural analyses of a helical rotor have been implemented by finite element method. The structural analyses of the wind power tree which support four helical rotor, have been performed under a wind load, a rotational velocity of a rotor, and dead weight.