• 한국기계가공학회지
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• 제14권4호
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• pp.140-145
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• 2015

In the present study, the structural safety of the bolt portion and collet tool structure of the pipe-fitting tool is analyzed by using the finite element technique. Two forces as piston forces with the magnitude of 187.5 Tons are applied to the inner and outer portions of the collet tool, respectively. A structural load of 750 Tons is applied to the bolt portion. In the analysis results, it is found that the structure becomes safe under the current loading conditions. The reliability rating of the pipe is calculated in this study. The material properties of the actual material are evaluated by using mechanical testing. Therefore, the material properties are used to carry out static structural and optimization analysis.

• Structural Engineering and Mechanics
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• 제31권3호
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• pp.315-331
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• 2009

Mechanical connections are recognized as extremely important elements in the aspect of strength and structural safety. However, classical structural model does not consider the connection stiffness properties, and are based on models with pinned or rigid joints only. In fact, mechanical connections are deformable and behave not linearly, affecting the whole structure and inducing nonlinear behavior as well. The quantification of this effect, however, depends on the description of the working of the connectors and the wood response under embedment. The theoretical modeling of wood structures with semi-rigid connections involves not only the structural analysis, but also the modeling of both single and grouped moment resisting connectors and the study of the wood properties under embedment. The proposal of this paper is to approach these aspects, and to quantitatively study the influence of the moment resistant connection in wooden framed structures. Comparisons between rigid and semi-rigid connections and between linear and nonlinear analysis lead to quantitative results.

• 한국세라믹학회지
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• 제47권4호
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• pp.290-295
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• 2010

This study has been focused on properties of mirror surface grinding technology by ELID(Electrolytic In-process Dressing) for structural ceramics using in high precision structural parts as like semi-conductor manufacturing processes. The experimental studies have been carried out to get mirror surface for grinding of structural ceramics, SiC, $Al_2O_3$ and AlN. Grinding process of the ceramics is carried out with varying mesh type, depth of cut and feed rate using diamond wheel. The machining result of the surface roughness and condition of ground surface, have been analyzed by use of surface roughness tester, SEM, AFM and three dimensional surface profiler measurement system.

• 전산구조공학
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• 제17권3호
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• pp.45-52
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• 2004

• 전산구조공학
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• 제29권2호
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• pp.33-37
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• 2016

• 한국의류산업학회지
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• 제7권5호
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• pp.553-559
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• 2005

Hand characteristics related with structural properties of fabrics have something to do with mechanical properties of fabric. In this study, the mechanical properties and hand characteristics have been analyzed according to fabric structural parameters such as the weave structure and the linear density of weft of cotton fabric. Mechanical properties have been used by KES-FB system which measures hand characteristics and mechanical properties of fabric. Linear density of weft, tensile, bending, and shear properties are decreasing with increasing weft linear density, and there is no considerable effects on compression and surface properties. In case of formability with weft linear density, B/W, 2HG/G, 2HB/B, 2HB/W, $\sqrt[3]{B/W}$, $\sqrt{2HB/W}$, W/T except MMD/SMD, WC/T, and WC/W have been effected. There is a high correlation between the crimp, tightness, hand, formability and mechanical properties specially tensile linearity, bending, shear, and compression properties. The weft crimp influences the bending rigidity, shear properties, and the tightness which have effects on the tensile linearity, bending, shear, compression properties, hand, and formability.

• 한국전기전자재료학회논문지
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• 제19권4호
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• pp.322-327
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• 2006

CdS films have been prepared on polycarbonate, polyethylene terephthalate, and Coming 7059 substrates by r.f magnetron sputtering technique at room temperature. A comparison of the properties of the films deposited on polymer and glass substrates was performed. In addition, the influence of the sputter power on the structural and optical properties of these films was evaluated. The XRD measurements revealed that CdS films were polycrystalline and retained the mixed structure of hexagonal wurtzite and cubic phase, regardless of substrate types. As the sputter power was increased from 75 to 150 Watt, the structure of CdS films was converted from the mixed of hexagonal and cubic phase to hexagonal phase. The morphology of CdS films is found to be continuous and dense. Also, the grain of CdS films is larger with increasing the sputter power. The average transmittance exceeded 80 % in the visible spectrum for all films and decreases slightly with the sputter power.

• Steel and Composite Structures
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• 제21권3호
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• pp.517-536
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• 2016

Thick steel plate is commonly found with mega steel structures but its properties have not been fully explored. Grade Q345GJ-C steel plate with thickness ranging from 60 mm to 120 mm are studied in this paper. Both the static and cyclic performance of material in different directions (horizontal and through-thickness directions) and locations (outer surface, 1/4 thickness and mid-depth) are experimentally obtained. The accumulative damage during cyclic loading is also calculated by using bilinear mixed hardening (BMH) constitutive relationship together with the Lemaitre's damage model. Results show that the static properties are better at the outer surface of thick steel plates than those at mid-depth. Properties in through-thickness direction are similar to those at mid-depth in the horizontal direction. The cyclic performance at different locations of a given plate is similar within the range of strain amplitude studied. However, when damage parameters identified from monotonic tensile tests are included in the numerical simulation of cyclic loading tests, damage is found accumulating faster at mid-depth than close to outer surface.

• 한국세라믹학회지
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• 제44권6호
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• pp.319-324
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• 2007

The structural properties of $SiO_2$ liquid at finite temperatures have been investigated by molecular dynamics (MD) simulations utilizing the Tersoff interatomic potential. During cooling process, the $SiO_2$ liquid structure quenched with a cooling rate of $1.0{\times}10^{11}K/sec$ shows the traditional properties observed in the experiments. The coordination defects of system decrease with decreasing temperature up to 17%. The $SiO_2$ glass quenched up to 1600 K contains defects consisting of the fivefold coordination of Si, and the threefold coordination of O atoms. The calculated diffusion coefficients which are calculated by monitoring. the mean-square displacement of atoms drop to almost zero below 3000 K ($<10^{-6}\;cm^2/sec$) but has a fluctuations at low temperature. The structure properties of $SiO_2$ liquid shows a significant dependence on the temperature during cooling process. Bond-angle distribution at around $120^{\circ}$ originate from the O and Si atoms consisting of the over-coordinated O atoms.

• E2M - 전기 전자와 첨단 소재
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• 제7권3호
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• pp.187-199
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• 1994

In order to find an effect of structural changes due to variation of addition ratio of anhydride hardener and postcuring herat-treatments upon electrical properties of epoxy composites, the dielectric properties over a frequency range from 30[Hz] to l[MHz] were investigated in the temperature range of 20-180[.deg. C]. From the dielectric properties, the a peaks related with glass-transition phenomena of epoxy network appeared near 130[.deg. C], the conduction loss in high temperature region above 150[.deg. C] due to thermal dissociation of hardener started off with the low frequency side and the .betha. peak concerned with contribution of movable unreacted terminal epoxy groups and curing agents in the glass states concurred with the high-frequency side below 20[.deg. C]. And an effect of an hydride hardener upon structural changes and of postcuring heat treatments upon structural stability in epoxy composites would be explained through the estimation of the distribution of relaxation times and the activation energy for a .alpha. peak according to the WLF equations.