• 한국염색가공학회지
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• 제26권3호
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• pp.218-229
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• 2014

The wearing comfort of garment is governed by two kinds of characteristics such as moisture and thermal transport properties and mechanical properties of fabrics. The porosity influenced by yarn and fabric structural parameters is known as main factor for wearing comfort of garment related to the moisture and thermal transport properties. This study investigated effect of porosity of composite yarns to the moisture and thermal comfort properties of composite fabrics made of hollow composite DTY and ATY yarns. The theoretical porosity and pore size were inversely proportional to cover factor of fabric, but cover factor was not correlated with experimental pore size. The wicking property of hydrophobic PET filament fabric showed inferior result irrespective of porosity, pore size and cover factor. The drying rate was superior at composite fabrics with high pore size and low cover factor, and pore size was dominant factor for drying property. On the other hand, thermal conductivity of composite fabric was mainly influenced by cover factor and not influenced by porosity. Air permeability was influenced by both porosity and cover factor and was highly increased with increasing porosity and decreasing fabric cover factor.

• 한국세라믹학회지
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• 제26권5호
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• pp.617-624
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• 1989

Piezoelectric composites of O-3 connectivity were prepared by thermosetting barium titanate-phenolic resin composite under various cruing pressure. Among three kinds of pore in O-3 type ceramic-polymer composite, such as matrix pores, particle pores, and ceramic-polymer interface pores, the effect of interface porosity on the dielectric and piezoelectric constant was investigated. In pure barium titanate ceramics, the porosity factor of dielectric and piezoelectric constants were 5.7 and 5.0, respectively. However, in BaTiO3-polymer composite, the interface porosity factor of the piezoelectric constant was greater than that of the dielectric constant, interface porosity factor b in d33 was 9.8 and in r 4.6. On the other, piezoelectric voltage constant g33 was independent of the porosity of barium titanate ceramics. But in composite system, the piezoelectric voltage constant g33 was decreased with interface porosity.

• Geomechanics and Engineering
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• 제28권1호
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• pp.77-87
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• 2022

Many geotechnical analyses require the investigation of water flow within partially saturated soil zone to incorporate the effect of climatic conditions. It is widely understood that the hydraulic properties of the partially saturated soil should be included in the transient seepage analyses. However, the characteristics of dual porosity soils with dual-mode water retention curve are normally modelled using single-mode mathematical equation for simplification of the analysis. In reality, the rainwater flow can be affected significantly by the dual-mode hydraulic properties of the soil. This paper presents the variations of safety factor for dual porosity soil slope with dual-mode water retention curve and dual-mode unsaturated permeability. This paper includes the development of the new dual-mode unsaturated permeability to represent the characteristics of soil with the dual-mode water retention curve. The finite element analyses were conducted to examine the role of dual-mode water retention curve and dual-mode unsaturated permeability on the variations of safety factor under rainfall loading. The results indicate that the safety factor variations of dual porosity soil slope modelled using the dual-mode water retention curve and the unsaturated permeability equation are lower than those of dual porosity slope modelled using single-mode water retention curve and unsaturated permeability equations.

• Steel and Composite Structures
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• 제51권6호
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• pp.601-617
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• 2024

This work aims to explore the static behaviour of a tapered functionally graded porous plate (FGPP) with even and uneven porosity distributions resting on two parametric elastic foundations. The plate under investigation is subjected to bi-sinusoidal loading and the edges of the plate are exposed to different combinations of edge restrictions. In order to examin the static behaviour, bending factors (BF) related to bending and normal stresses have been evaluated using classical plate theory. To achieve this, the governing equations have been derived employing the energy concept. And to solve it, the Rayleigh-Ritz method with an algebraic function has been utilised; it is simple, precise, and computationally intensive. After convergence and validation analyses, new findings are made available. The BF of the plate have been exhaustively examined to explain the influence of aspect ratios, material property index, porosity factor, taper factor, and Winkler and Pasternak stiffness. It is observed that the BF of an elastically supported FGPP are influenced by the index of material propery and the aspect ratio. Findings also indicate that the impact of porosity is more when it is spread evenly, as opposed to when it is unevenly distributed. Further, the deformed plate's structure is significantly influenced by the different thickness variations. Examination of bending characteristics of FGPP having different new cases of thickness variations with different types of porosity distribution under fifteen different mixed edge constraints is the prime novality of this work. Results presented are reliable enough to be taken into account for future studies.

• Structural Engineering and Mechanics
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• 제83권5호
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• pp.609-615
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• 2022

A numerical approach for dynamic stability analysis of sandwich plates has been provided using Chebyshev-Ritz-Bolotin approach. The sandwich plate with porous core has been formulated according to a higher-order plate. All of material properties are assumed to be dependent of porosity factor which determines the amount or volume of pores. The sandwich plate has also been assumed to be under periodic in-plane loading of compressive type. It will be shown that stability boundaries of the sandwich plate are dependent on static and dynamical load factors, porosity factor, porosity variation and core thickness.

• 한국기계가공학회지
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• 제6권2호
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• pp.9-16
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• 2007

The fatigue test of the fillet weldments were executed with different groove angles and porosity. The groove angles of $90^{\circ}$, $45^{\circ}$ and $55^{\circ}$ were compared with fatigue lives. After the fillet weldment failure, the porosity which found at the fractured surface were observed to account the effect on fatigue life. Finite element analysis were performed to correlate the fatigue strength and the size & the location of porosity. The stress-strain field were severely affected by the length of notch and the size & location of porosity. Based on the quantitative analysis of porosity effect, the total volume of porosity was key factor for fatigue strength of the fillet weldment.

• Advances in nano research
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• 제8권4호
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• pp.283-292
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• 2020

In the present research, differential quadrature (DQ) method has been utilized for investigating free vibrations of porous functionally graded (FG) micro/nano beams in thermal environments. The exact location of neutral axis in FG material has been assumed where the material properties are described via porosity-dependent power-law functions. A scale factor related to couple stresses has been employed for describing size effect. The formulation of scale-dependent beam has been presented based upon a refined beam theory needless of shear correction factors. The governing equations and the associated boundary conditions have been established via Hamilton's rule and then they are solved implementing DQ method. Several graphs are provided which emphasis on the role of porosity dispersion type, porosity volume, temperature variation, scale factor and FG material index on free vibrational behavior of small scale beams.

• 전자공학회논문지A
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• 제32A권1호
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• pp.97-102
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• 1995

The ferromagnetic resonance properties of Mg ferrites which have various porosity grain size, and saturation magnetization are measured at one frequency. This allows a determination of the anisotropy field(Ha). The saturation magnetization multiplied by porosity is the resonance magnetic field. As the saturation magnetization increases, the linewidth decerases due to decrement of magnetic inhomogenity in sample. the porosity is a major factor broadening the linewidth for Mg ferrite when porosity is more thatn 6%, and the anisotropy field is dominant when porosity is less than 6%.

• 한국의류산업학회지
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• 제20권4호
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• pp.457-463
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• 2018

This study examined the water absorption and drying properties of the thirteen types of the knitted fabrics for sports wear. These physical properties were analysed with relation to the constituent fiber cross-sectional shape and structure parameters of the knitted fabrics by regression analysis. Absorption and drying properties of the knitted fabric specimens were increased with increasing the porosity of the constituent yarns, which was attributed to the capillary channels in the yarns. The water absorption and drying properties were increased and decreased with increasing tightness factor and stitch density of the knitted fabric. The absorption property of the knitted fabric for perspiration absorption and fast dry sport-wear clothing was mostly influenced mostly by fiber cross-sectional shape and its characteristics, whereas, drying property was dependent on the structural parameters of the knitted fabric such as tightness factor and stitch density. Therefore, superior perspiration absorption and fast drying knitted fabric could be obtained in the fabric structure with optimum tightness factor and stitch density, and constituent yarn structure with non-circular fiber crosssection and high porosity. GATS method and MMT method are used to measure sweating fast drying properties and it is necessary to carry out studies using these measurement methods in order to compare with the results of this study.

• 한국세라믹학회지
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• 제46권3호
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• pp.275-281
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• 2009

Porous materials were manufactured by hydrothermal treatment of waste bottle glass without foam agent. Factorial design was applied to analyze data by statistical methods and deal with the important factors for a process. The largest effect for porosity was for temperature of hydrothermal treatment. Amount of water and temperature-water interaction appeared to have little effect. The particle size of raw material was also identified as a major factor by one-way ANOVA and the porosity decreased as the size increased. The sintering temperature was not statistically significant for the porosity but was significant for the pore size. The porous material had compressive strength and thermal conductivity comparing with those of ALC (autoclaved lightweight concrete), although it has higher porosity than for ALC.