• Advances in materials Research
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• v.8 no.3
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• pp.219-235
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• 2019

This research is devoted to analyzing mechanical-thermal post-buckling behavior of a micro-size beam reinforced with graphene platelets (GPLs) based on geometric imperfection effects. Graphene platelets have three types of dispersion within the structure including uniform-type, linear-type and nonlinear-type. The micro-size beam is considered to be perfect (ideal) or imperfect. Buckling mode shape of the micro-size beam has been assumed as geometric imperfection. Modified couple stress theory has been used for describing scale-dependent character of the beam having micro dimension. Via an analytical procedure, post-buckling path of the micro-size beam has been derived. It will be demonstrated that nonlinear buckling characteristics of the micro-size beam are dependent on geometric imperfection amplitude, thermal loading, graphene distribution and couple stress effects.

• Transactions of Materials Processing
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• v.9 no.6
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• pp.663-669
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• 2000

A material model has been presented, at the continuum level, for the representation of superplastic deformation coupled with microstructural evolution. The model presented enables the effects of the spatial variation of distributions of grain size to be predicted at the process level. The model has been tested under conditions of both homogeneous and inhomogeneous stress and strain by carrying out detailed comparison of predicted distributions of grain size and their evolutions with experimentally obtained data. Experimental measurements have shown the extent of the spatial variation of the distribution of grain size that exists in the titanium alloy, Ti-6Al-4V. It is shown that whilst not large, the variations in grain size distributions are sufficient to lead to the development of inhomogeneous deformation in test pieces, which ultimately result in localisation of strain and failure.

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.327.1-327.1
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• 2007

• Journal of the Korean Mathematical Society
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• v.57 no.6
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• pp.1323-1333
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• 2020

In 2009, Borg [2] suggested a conjecture concerning the size of a t-intersecting k-uniform family of faces of an arbitrary simplicial complex. In this paper, we give a strengthening of Borg's conjecture for shifted simplicial complexes using algebraic shifting.

• Journal of applied mathematics & informatics
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• v.27 no.5_6
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• pp.1481-1488
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• 2009

A construction of Cartesian authentication codes over unitary geometry is presented and its size parameters are computed. Assuming that the encoding rules are chosen according to a uniform probability distribution, the probabilities of success for different types of attacks are also computed.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3818-3821
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• 2010

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.6
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• pp.860-868
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• 2009

To provide adequate fit for women over a range of sizes, the grading process should reflect their body dimensions. Current methods of creating sized garments are not addressing the need for a good or even an adequate fit for the easy-order system. This study suggests a grading rule allocating system that can improve the appropriateness of clothing for uniform easy-order system. Also, the study proposes a bi-directional grading method subdivided to horizontal and vertical direction. The grading rule allocating system suggested the size increments which improve the fitness of uniform. Using the 5th Size Korea data, the crosstabulation was conducted with 1305 females in the age group $20{\sim}49$ years, and the size increments including $155\sim165$ of height section and $79\sim94$ of bust section, was selected for easy-order system. Also, the bi-directional grading method subdivided in horizontal and vertical direction was followed by factor analysis based on the circumference and height. And the grading rules were calculated by regression analysis.

• Journal of the Korean Ceramic Society
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• v.35 no.5
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• pp.499-504
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• 1998

ZnO varistors having a composition of 98.0 mol% ZnO 1.0 mol% $Bi_2O_3$ 0.5 mol% $MnO_2$ were prepared by the Pechini process and the sintering behavior and electrical characteristics were studied. ZnO varis-색 powder with $1.5\mu\textrm{m}$ mean diameter and narow particle size distribution was obtained using the Pechni pro-cess. Typical intermediate stage grain growth of liquid phase sintering was observed by sintering at $1100^{\circ}C$ At this temperature ZnO varistors having uniform grain size and Bi-rich liquid phase distributed uniformly along grain boundaries were prepared. The nonlinear coefficients of the ZnO varistors were in the range of 40-60 The breakdown voltages of the varistors were nearly inversely propeortional to the grain size which reflects that ZnO varistors prepared by the Pechini process have uniform distribution of Bi-rich liquid phase along grain boundaries It is believed that the microstructures of ZnO varistors can be controlled effectively by using the Pechini process which makes the control of the electrical properties of ZnO varistors possible.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.613-619
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• 2022

The extended Maxwell-Wagner polarization model is employed to describe the ER(Electrorheological) behavior of bi-dispersed ER suspensions, and solutions to the equation of motion are obtained by dynamic simulation. Under the same particle volume fraction, it is found that the dynamic yield stresses of uniform size suspensions do not depend on the particle size. Compared with uniform size suspensions, the dynamic yield stress is reduced for ER fluids consisting of two kinds of particles with different sizes. Compared with the dynamic yield stress behavior, for ${\dot{\gamma}}^*$≧0.01 the shear stress shows different behaviors depending on the particle sizes and the raio of different size particles. The simulation results show the nonlinear ER behavior (∆_𝛕 ∝ Eⁿ, n ≈ 1.55) of the conducting particle ER suspensions.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.3
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• pp.298-304
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• 2010

In order to calculate the aerosol bulk densities of $PM_{1.0}$ and $PM_{10}$, aerosol mass and number concentrations were measured for the period of December 2008~April 2009. $PM_{1.0}$ and $PM_{10}$ mass concentrations were measured using a cascade impactor (Micro-Orifice Uniform Deposit Impactor, MOUDI) while their volume concentrations were calculated based on number concentrations from an environmental dust monitor (EDM). Normal aerosol size distribution fitting functions were retrieved for number size distribution since aerosols < $2.5{\mu}m$ were measured from the EDM. Strong correlation was found between $PM_{1.0}$ mass and volume concentrations obtained with a $R^2$ of 0.95. The calculated average bulk densities of $PM_{1.0}$ and $PM_{10}$ were $1.97{\pm}0.33g/cm^3$ and $2.15{\pm}0.18g/cm^3$, respectively.