• Advances in environmental research
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• v.6 no.2
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• pp.127-137
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• 2017

Cotton is the major fiber crop in Pakistan that accounts for 2% of total national gross domestic product (GDP). After picking of cotton, the dry stalks are major organic waste that has no fate except burning to cook food in villages. Present research focuses use of cotton stalks as feedstock for biochar production, its characterization and effects on soil characteristics. Dry cotton stalks collected from agricultural field of Bahauddin Zakariya University, Multan, Pakistan were combusted under anaerobic conditions at $450^{\circ}C$. The physicochemical analysis of biochar and cotton stalks show higher values of % total carbon, phosphorus and potassium concentrations in biochar as compared to cotton stalks. The concentration of nitrogen was decreased in biochar. Similarly biochar had greater values of fixed carbon that suggest its role for carbon sequestration and as a soil amendment. The fourier transformation infrared spectroscopic spectra (FTIR) of cotton stalks and biochar exposed more acidic groups in biochar as compared to cotton stalks. The newly developed functional groups in biochar have vital role in increasing surface properties, cation exchange capacity, and water holding capacity, and are responsible for heavy metal remediation in contaminated soil. In a further test, results show increase in the water holding capacity and nutrient retention by a sandy soil amended with biochar. It is concluded that cotton stalks can be effectively used to prepare biochar.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.3
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• pp.611-623
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• 1998

The delamination fracture of multidirectional carbon-fiber/epoxy laminates under the Mode I condition has been studied using the modified beam analysis for a fracture mechanics approach. It was found that the variation of fracture energy $G_IC$ with increasing length of the propagating crack exhibited a minimum for the pure interlaminar fracture and a maximum for the intraply fracture,i.e. a rising "R-curve", which was strongly affected by the degree of fiber bridging and crack-tip splitting arising in the global delamination. The maximum $G_IC$ value was significantly dependent on such types of delamination as no crack jumping, crack jumping into the adjacent ply and edge-delamination. It was shown also that the value of "effective flexural modulus" estimated from the modified beam analysis increased much with the development of fiber bridging behind the crack tip.ehind the crack tip.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.10a
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• pp.153-157
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• 2001

Interfacial properties and microfailure modes of electrodeposition (ED) treated carbon fiber reinforced polyetherimide (PEI) toughened epoxy composite were investigated using microdroplet test and the measurement of surface wettability. As PEI content increased, Interfacial shear strength (IFSS) increased due to enhanced toughness and plastic deformation of PEI. In the untreated case, IFSS increased with adding PEI content, and IFSS of pure PEI matrix showed the highest. On the other hand, for ED-treated case IFSS increased with PEI content with rather low improvement rate. The work of adhesion between fiber and matrix was not directly proportional to IFSS for both the untreated and ED-treated cases. The matrix toughness might contribute to IFSS more likely than the surface wettability. Interfacial properties of epoxy-PEI composite can be affected efficiently by both the control of matrix toughness and ED treatment.

• New & Renewable Energy
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• v.2 no.2 s.6
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• pp.75-80
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• 2006

The effective thermal conductivities of $Mm(La_{0.6-0.8})Ni_{4.0}Co_{0.6}Mn_{0.2}Al_{0.2}$ [TL-492] with hydrogen and helium have been examined. Experiment results show that pressure has great influence on effective thermal conductivity in low pressure range [below 0.5 MPa]. And that influence decreases rapidly with increase of gas pressure. The reason is at low pressure, the mean free path of gas becomes greater than effective thickness of gas film which is important to the heat transfer mechanism in this research. And, carbon fibers have been used to try to enhance the poor thermal conductivity of TL-492. Three types of carbon fibers and three mass fractions have been examined and compared. Naturally, the highest effective thermal conductivity has been reached with carbon fiber which has highest thermal conductivity, and highest mass fraction. This method has acquired 4.33 times higher thermal conductivity than pure metal hydrides with quite low quantity of additives, only 0.99 wt% of carbon fiber. This is a good result comparing to other method which can reach higher effective thermal conductivity but needs much higher mass fraction of additives too.

• Journal of the Korea Fashion and Costume Design Association
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• v.4 no.2
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• pp.127-138
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• 2002

The recent fashion trend of knit wear is now changing to the various fibrous color combination which emphasizes the plain texture. It supports the human body curvature which is influenced by the slim style of woven wear. In this research work, the general characteristics and knit wear fashion trend are studied. The metallic fiber and fancy yarn are used widely as fiber materials for knit in nowadays. However, the light and functional materials are preferred. The general characteristics of knit which gives the feeling of light and warm are still prevailing using pure wool, kid mohair, and mixed wool with polyester. In order to provide the soft touch feeling, smoothness of fine fiber, and feeling of sponge, several kinds of finishing techniques such as bulky, felting, bonding, and quilting process are usually adopted. The knit wear fashion trend is mainly consisted of the basic design items, and it gives the feeling of luxurious and elegance. The more youthful feeling is adapted for the general style of knit wear of the certain target age. The woven wear trend such as season color, line and pattern are applied in knit wear trend in recent days.

• Computational Structural Engineering
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• v.7 no.2
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• pp.101-109
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• 1994

A degenerated cylindrical shell element for modeling glass fiber reinforced plastic pipes is developed and its performance for static structural analysis under internal uniform pressure is evaluated. The element is a nine node degenerated solid shell element with reduced integration technique, addition of nonconforming displacement modes, and assumed strain method to improve convergence of analysis. Several numerical examples are solved and compared with analytical solutions and other F.E.M programs, The results show that the increment of fiber orientation in the GFRP pipes with reference to the longitudinal axis cause less radial displacements and much stiffness in the pipes. This is reasonable since the internal pressure will primarily cause hoop stresses in the ring and 90-angle ply GFRP ring carry these efficiently in pure tension.

• Journal of the Optical Society of Korea
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• v.19 no.5
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• pp.449-455
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• 2015

In this study we propose a new photonic crystal fiber (PCF) design that simultaneously offers broadband single-mode operation, high birefringence, and large normal dispersion in the optical-communication wavelength regime. The waveguide is based on a hybrid square-lattice PCF (HS-PCF) that has circular air holes of two different diameters alternating in the cladding, plus a pure silica defect at the center. The optical properties of the guided modes are analyzed numerically by the finite-element method (FEM) with a perfectly matched layer as the boundary condition. The optimized HS-PCF has a dispersion coefficient of $-601.67\;ps\;nm^{-1}\;km^{-1}$ and a high birefringence of $1.025{\times}10^{-2}$ at $1.55{\mu}m$. In addition, over the S+C+L+U wavelength bands the proposed HS-PCF with ultraflat birefringence with a slope on the order of $10^{-5}$.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.133-135
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• 2003

The removal of dissolved oxygen(DO) from water was studied using a poly(vinyliene fluoride)(PVDF) hollow fiber membrane contactor(HFMC) with the vacuum degassing process(VDP), Asymmetric porous PVDF hollow fiber membranes (HFM) for membrane contactor were prepared by a wet phase inversion method. In spinning of these PVDF hollow fibers, dimethy lacetamide (DMAc), LiCl and pure water were used as a solvent, a pore-forming additive and internal/external coagulant, respectively. The characteristics of the structure(pore size, porosity etc.) of the prepared PVDF HFMs as a function of concentration of pore-forming additive in polymer dope solution were studied. Also, the removal efficiency of DO from water according to flow rates of water, using PVDF HFMC with VDP, was studied. The performance of the asymmetric porous PVDF HFMC and a symmetric porous PP HFMC commercialized were compared. As a result, the asymmetric porous PVDF HFMC showed higher removal efficiency of DO than that of a symmetric porous PP HFMC.

• Macromolecular Research
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• v.16 no.4
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• pp.367-372
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• 2008

We fabricated tetra(5-n-nonyl-8-tert-butyl-2,3-pyrazino[2,3-b]indolo)porphyrazinato copper(II) (Cu-Pc-$C_8$) Langmuir-Blodgett (LB) films. We further investigated the influence of arachidic acid (AA) as a transfer promoter, as well as the effect of dipping speed, on the deposition of the films on hydrophilic and hydrophobic substrates. In the case of pure Cu-Pc-$C_8$ LB deposition on a hydrophilic substrate, the transfer ratio was close to one for up-stroke depositions, but the previously deposited film was peeled off and re-spread onto water at down-stroke depositions. Whereas the stability of the Cu-Pc-$C_8$ LB films was not improved by AA addition on hydrophilic substrates, the deposition of Cu-Pc-$C_8$ was significantly improved by the presence of AA on a hydrophobic substrate. The AA-assisted deposition had transfer ratio of close to 1 and was essentially stable up to 10-layer depositions. Comparison of the UV-visible spectrum of a Cu-Pc-$C_8$/AA LB film with that of Cu-Pc-$C_8$/AA solution in dichloroethane revealed that the Soret and Q bands for the Cu-Pc-$C_8$/AA LB film were broadened and red-shifted due to the aggregation of phthalocyanines upon assembly in the LB film.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.5370-5375
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• 2011

To introduce the antibacterial activity, ACF(activated carbon fiber) was impregnated by nano-sized Ag, Mn, and phosphoric acid. It was observed by the SEM analysis that Ag, Mn and phosphoric acid were properly impregnated at the ACF. The impregnated ACF showed lower adsorption performance than the pure ACF. It is found that ACFs impregnated by nano-sized Ag or phosphoric acid have a good antibacterial activity against bacillus cereus and salmonella entaritidis. but in the case of ACF impregnated with Mn, it have not any antibacterial effect on the bacillus cereus and salmonella entaritidis.