• Textile Coloration and Finishing
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• v.33 no.1
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• pp.10-23
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• 2021

In order to synthesize the dye suitable for supercritical carbon dioxide(ScCO2) dyeing, a series of azo based disperse dyes were prepared using various aniline derivatives as diazo components and indol derivatives as coupling components. Dyeing process in ScCO2 of the synthesized dyes was performed on PET fiber at 120℃ for 2 hrs under 250bar pressure with 0.5% o.w.f. of dye concentration. The absorption maxima varied from 400 to 580nm depending on the substituted groups in aniline derivatives and the indol derivatives. The dyes showed high molar extinction coefficients(ε) of 27,000~61,000M-1cm-1. Dyed PET fiber exhibited excellent brightness and good light, washing and perspiration(acid/alkali) fastness properties.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.25-30
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• 2017

Carbon-fiber-reinforced plastic (CFRP) composite materials have been widely used in various industrial fields because the design variables can be adjusted according to the application of the required structure. Thermosetting and thermoplastic resins are used as the base materials of CFRP composites for the lightweight construction of automotive components. Thermoplastics have several advantages such as no curing and recyclability compared to thermosetting resin. In this study, CFRP composites were made using the Long-Fiber Thermoplastic-Direct (LFT-D) process. The LFT-D process includes an in-line production system that directly impregnates a thermoplastic resin, extrudes the composite material, and molds it. This process increases the strength and decreases the molding time. The tensile strength characteristics on the mechanical properties of CFRP were analyzed according to the parameters of LFT-D based on thermoplastics. To analyze the properties of CFRP, the specimens were prepared based on the tensile test standard ASTM 3039 of composite materials.

• Advances in environmental research
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• v.5 no.1
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• pp.61-77
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• 2016

$NanoTiO_2$ was synthesized by ultrasonication assisted sol-gel process and subjected to iron doping and carbon-iron codoping. The synthesized catalysts were characterized by XRD, HR-SEM, EDX, UV-Vis absorption spectroscopy and BET specific surface area analysis. The average crystallite size of pure $TiO_2$ was in the range of 30 - 33 nm, and that of Fe-$TiO_2$ and C-Fe $TiO_2$ was in the range of 7 - 13 nm respectively. The specific surface area of the iron doped and carbon-iron codoped nanoparticles was around $105m^2/g$ and $91m^2/g$ respectively. The coupled semiconductor photo-Fenton's activity of the synthesized catalysts was evaluated by the degradation of a cationic dye (C.I. Basic blue 9) and an anionic dye (C.I. Acid orange 52) with concurrent investigation on the operating variables such as pH, catalyst dosage, oxidant concentration and initial pollutant concentration. The most efficient C-Fe codoped catalyst was found to effectively destruct synthetic dyes and potentially treat real textile effluent achieving 93.4% of COD removal under minimal solar intensity (35-40 kiloLUX). This reveals the practical applicability of the process for the treatment of real wastewater in both high and low insolation regimes.

• Proceedings of the Korean Fiber Society Conference
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• 2007.11a
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• pp.263-264
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• 2007

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• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2010.03a
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• pp.113-114
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• 2010

• Composites Research
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• v.37 no.3
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• pp.197-203
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• 2024

Mechanical, electrical and thermal properties of polymer composites can be improved simultaneously by incorporating carbon fibers (CFs), which are beneficial for improving the mechanical properties, and multi-walled carbon nanotubes (MWCNTs), which are advantageous for improving the conductive properties. In this study, MWCNTs were incorporated into carbon long fiber thermoplastic (CLFT), which has excellent mass production processability and excellent mechanical properties, to control electrical and thermal properties. The mechanical and electrical properties of the prepared composites were most significantly influenced by the amount of filler incorporated. On the other hand, the thermal properties were improved due to the formation of a filler network interconnected by the incorporation of MWCNTs. By adjusting the filler amount, filler composition, and filler network structure of MWCNT-incorporated CLFT, the mechanical, electrical, and thermal properties could be controlled.

• Fibers and Polymers
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• v.6 no.4
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• pp.284-288
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• 2005

Poly(ethylene terephthalate) was annealed at different temperature and pressure of supercritical carbon dioxide $(CO_2)$ using samples quenched from the melt. Crystallization and molecular relaxation behavior due to $CO_2-annealing$ of samples were investigated using differential scanning calorimetric and dynamic mechanical measurements. The glass transition and crystallization temperatures significantly decreased with increasing temperature and pressure of $CO_2$. The dynamic mechanical measurement of samples annealed at $150^{\circ}C$ in supercritical $CO_2$ showed three relaxation peaks, corresponding to existence of different amorphous regimes such as rigid, intermediate, and mobile domains. As a result, the mobile chains were likely to facilitate crystallization in supercritical state. It also led to the decreased modulus of $CO_2-annealed$ samples with increasing pressure.

• Fibers and Polymers
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• v.1 no.1
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• pp.32-36
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• 2000

An alternative strategy to .educe the percolation threshold of carbon black (CB) in polymer blends was investigated using random copolymer ternary blends of polystyrene (PS), poly(methyl methacrylate)(PMMA), and a styrene-methyl methacrylate random copolymer (SMMA). The target morphology was to selectively locate CB particles in the encapsulating layer of SMMA during melt mixing. The CB used in this study is BP-2000 from Cabot and has a strong selective affinity to PS. Even when the CB was premixed with SMMA, it moves to the PS phase during the melt mixing. However, we also observed the CB particles located at the interface between SMMA and PS phases. Through this study it is found that the interaction between polymers and CB particles is critical for selectively localizing CB particles in multi-component polymer blends. Although appropriate processing condition may retard the movement of CB particles to the polymer phase with affinity, it cannot prevent it completely and locate them to the SMMA phase, which is not thermodynamically favored. To locate CB particles in an encapsulating layer of ternary polymer blends, first of all, polymers forming it should have selective affinity to CB.

• Textile Coloration and Finishing
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• v.30 no.4
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• pp.313-320
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• 2018

As carbon fiber reinforced composites(CFRP) are widely used in aerospace, automobile, marine, and sports goods applications, they have been studied extensively by various researchers. However, CFRP have been pointed out because of machining problems such as delamination and burr phenomenons. Especially, hole machining process, drilling, has non-smooth features on inlet and outlet surfaces of drilled hole. This kind of machining problem can be controlled to some extent by using high modulus pitch-CF, which has considerable effects on fracture behavior of composite compared with only PAN CF composite. Therefore, PAN and pitch hybridized CF composites were prepared having high strength and modulus. The results demonstrate that the hybrid CFRP specimens with pitch CF offer the good potential to enhance modulus as well as strength properties. Dynamic mechanical, flexural, and impact properties were measured and analyzed. Morphological surface of the composites were also observed by IFS-28, canon after hole machining.

• Earthquakes and Structures
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• v.23 no.5
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• pp.473-491
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• 2022

The research investigates experimentally the effect of confinement on structural behavior at the ends of beam-column in reinforced concrete (RC) frames. In the experimental study, five specimens consisting of 1/3-scaled RC frames having single-bay, representing the traditional deficiencies of existing buildings constructed without receiving proper engineering service is investigated. The RC frame specimens were produced to represent most of the existing buildings in Turkey that have damage potential. To decrease the probable damage to the existing buildings exposed to earthquakes, the carbon Textile Reinforced Mortar (TRM) strengthening technique (fully wrapping) was used on the ends of the RC frame elements to increase the energy dissipation and deformation capacity. The specimens were tested under reversed cyclic lateral loading with constant axial loads. They were constructed satisfying the weak column-strong beam condition and consisting of low-strength concrete, such as compressive strength of 15 MPa. The test results were compared and evaluated considering stiffness, strength, energy dissipation capacity, structural damping, ductility, and damage propagation in detail. Comprehensive investigations of these experimental results reveal that the strengthening of a brittle frame with fully-TRM wrapping with non-anchored was effective in increasing the stiffness, ductility, and energy dissipation capacities of RC bare frames. It was also observed that the frame-only-retrofitting with an infill wall is not enough to increase the ductility capacity. In this case, both the frame and infill wall must be retrofitted with TRM composite to increase the stiffness, lateral load carrying, ductility and energy dissipation capacities of RC frames. The presented strengthening method can be an alternative strengthening technique to enhance the seismic performance of existing or moderately damaged RC buildings.