• Elastomers and Composites
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• v.51 no.4
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• pp.308-316
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• 2016

The rubber materials are widely used in automobile industry due to their capability of a large amount of elastic deformation under a force. Current trend of design process requires prediction of functional properties of parts at early stage. The behavior of rubber material can be modeled using strain energy density function. In this study, five different strain energy density functions - Neo-Hookean model, Reduced Polynomial $2^{nd}$ model, Ogden $3^{rd}$ model, Arruda Boyce model and Van der Waals model - were used to estimate the behavior of carbon black added natural rubber under uniaxial load. Two kinds of tests - uniaxial tension test and biaxial tension test - were performed and used to correlate the coefficients of the strain energy density function. Numerical simulations were carried out using finite element analysis and compared with experimental results. Simulation revealed that Ogden $3^{rd}$ model predicted the behavior of carbon added natural rubber under uniaxial load regardless of experimental data selection for coefficient correlation. However, Reduced Polynomial $2^{nd}$, Ogden $3^{rd}$, and Van der Waals with uniaxial tension test and biaxial tension test data selected for coefficient correlation showed close estimation of behavior of biaxial tension test. Reduced Polynomial $2^{nd}$ model predicted the behavior of biaxial tension test most closely.

• The Korean Journal of Food And Nutrition
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• v.9 no.4
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• pp.496-499
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• 1996

In order to develop the functional diet food, characteristics of chitosan and silk fibroin composite was designed. Chitosan extracted from a prawn and silk fibroin was prepared from silkworm. The silk fibroin was dissolved rapidly in the 8M LiBr at a temperature of more than 4$0^{\circ}C$. Amino acid composition of fibroin composite revealed the same pattern that of native silk fibroin and regenerated silk fibroin. Predominant amino acid of chitosan-fibroin composite contained glycine, alanine, serine, tyrosine, threonine, and glutamic acid in order. According to the basis on the infrared spectrum, chitosan-silk fibroin composite is not distinguished differents composite ratio of chitosan and silk fibroin.

• Particle and aerosol research
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• v.13 no.4
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• pp.183-189
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• 2017

Potassium hexatitanate ($K_2Ti_6O_{13}$) with high thermal insulating capacity, good mechanical properties, and excellent chemical stability are promising functional materials in the field of reinforcing material, heat insulating paints and automotive brake linings. In this study, we successfully synthesized rod-shaped potassium hexatitanate ($K_2Ti_6O_{13}$) by aerosol spray drying and post heat treatment as an eco-friendly process. The $KHCO_3-TiO_2$ porous particles were firstly synthesized from a colloidal mixture of $K_2CO_3$ and $TiO_2$ via aerosol spray drying. Size of $KHCO_3-TiO_2$ porous particles was ranged from $1{\mu}m$ to $5{\mu}m$. The porous particles were then heated to fabricate rod-type $K_2Ti_6O_{13}$. The length and width of rod-type composites were affected by temperature and heating time. The length and width of $K_2Ti_6O_{13}$ were increased by 830 nm and 500 nm, respectively, as the reaction temperature and time increased.

• Journal of the Korean Ceramic Society
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• v.52 no.3
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• pp.173-179
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• 2015

We report the facile synthesis of graphene-$CdLa_2S_4$ composite through a facile solvothermal method at low temperature. The as-prepared products were characterized by X-ray diffraction (XRD) and by Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and BET analysis, revealing the uniform covering of the graphene nanosheet with $CdLa_2S_4$ nanocrystals. The as-prepared samples show a higher efficiency for the photocatalytic degradation of typical MB dye compared with P25 and $CdLa_2S_4$ bulk nanoparticles. The enhancement of visible-light-responsive photocatalytic properties by decolorization of Rh.B dye may be attributed to the following causes. Firstly, graphene nanosheet is capable of accepting, transporting and storing electrons, and thus retarding or hindering the recombination of the electrons with the holes remaining on the excited $CdLa_2S_4$ nanoparticles. Secondly, graphene nanosheet can increase the adsorption of pollutants. The final cause is that their extended light absorption range. This work not only offers a simple way to synthesize graphene-based composites via a one-step process at low temperature but also a path to obtain efficient functional materials for environmental purification and other applications.

• Elastomers and Composites
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• v.45 no.3
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• pp.156-164
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• 2010

Thermoplastic elastomers (TPEs) exhibit both elastomeric behaviors at used temperature range and melt processibility. Polyamide based thermoplastic elastomers (TPAEs) are segmented block copolymers with hard blocks consisting of polyamide segments, while the soft blocks usually consist of flexible segments having a low glass transition temperature. The TPAE is one of the engineering TPEs possessing high thermal stability, excellent mechanical performances, chemical resistance and excellent processibility. And they showed wide range of physical and functional properties depending upon the structure of each segment and their relative contents and the hybridization with various inorganic particles. In this review, synthesis, properties, and possible applications of TPAEs are summarized.

• Elastomers and Composites
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• v.49 no.4
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• pp.336-340
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• 2014

The functionality such as deodorant, antibacterial, ultraviolet shielding of titanium dioxide self-actuated photocatalyst $Weltouch^{TM}$ treated polyester fiber was characterized in conditions without light. The deodorizing capacity was maintained more than 97% reduction irrespective of before washing and after 20 times repeated washing, and antimicrobial capacity was also retained more than 99.9% reduction. Titanium dioxide self-actuated photocatalyst was still maintained to the surface of polyester fiber without separation even after 20 times repeated washing. According to washing durability of polyester fiber, the reduction effect for ammonia was still retained even after 20 times repeated washing as much as before washing. The ultraviolet shielding capacity was still maintained at least 83% irrespective of before washing and 20 times repeated washing.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.220-223
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• 2005

The rapid prototyping (RP) technology has been advanced for various applications such as verification of design, functional test. However, many RP machines still have low accuracy and limitation of applications for various materials. In this research, a hybrid RP system was developed to improve precision of micro parts. This hybrid system consists of deposition and material removal process by mechanical micro machining to fabricate nano composites using photo-curable polymer resin with various nano particles. In this work, using hybrid RP process with Multi-Walled Carbon Nano Tube (MWCNT) and hydroxyapatite, micro parts were fabricated. The precision of parts was evaluated based on the original CAD design, and to see the effect of nano particles on mechanical properties, tensile strength was measured. From the results of experiments, it was confirmed that the part made by hybrid process had higher precision, and the addition of nano particles improved mechanical properties.

• Korean Journal of Metals and Materials
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• v.50 no.3
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• pp.191-200
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• 2012

The purpose of this paper is to review the state of laser processing technology using metal powders. In recent years, a series of research and development efforts have been undertaken worldwide to develop laser processing technologies to fabricate metal-based parts. Layered manufacturing by the laser melting process is gaining ground for use in manufacturing rapid prototypes (RP), tools (RT) and functional end products. Selective laser sintering / melting (SLS/SLM) is one of the most rapidly growing rapid prototyping techniques. This is mainly due to the processes's suitability for almost any materials, including polymers, metals, ceramics and many types of composites. The interaction between the laser beam and the powder material used in the laser melting process is one of the dominant phenomena defining feasibility and quality. In the case of SLS, the powder is not fully melted during laser scanning, therefore the SLS-processed parts are not fully dense and have relatively low strength. To overcome this disadvantage, SLM and laser cladding (LC) processes have been used to enable full melting of the powder. Further studies on the laser processing technology will be continued due to the many potential applications that the technology offers.

• Elastomers and Composites
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• v.11 no.1
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• pp.54-62
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• 1976

It has been studied the graft copolymerization of glycidyl-methacrylate monomer containing two functional groups (vinyl- & epoxyl-) to chloroprene rubber. The reaction occured in the manner of chain transfer mechanism was carried out by means of solution polymerization in toluene in the presence of benzoyl peroxide as the radical initiator. The graft copolymer obtained from this work was analyzed by using IR spectrum, and the physical properties of the polymer such as the thermal behavior were also studied according to TG-DTA methods, and the potency of adhesiveness for the purpose of commercial application was investigated. Experimental results for the graft copolymerization are summarized as follows. 1) A small amount of initiator (0.5%) and 50% of monomer showed the best result for the grafting of monomer to the polymer chain of rubber while the 15% of rubber solution was found to be most suitable to raise either for the grafting ratio or the polymerization ratio. 2) Optimum temperature for better yield of graft copolymer was proved to he at $75^{\circ}C\sim80^{\circ}C$ while those of reaction time was to be $1\sim2$ hours.

• Structural Engineering and Mechanics
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• v.70 no.6
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• pp.683-702
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• 2019

The present study aims to analyze the magneto-electro-elastic (MEE) vibration of a functionally graded carbon nanotubes reinforced composites (FG-CNTRC) cylindrical shell. Electro-magnetic loads are applied to the structure and it is located on an elastic foundation which is simulated by visco-Pasternak type. The properties of the nano-composite shell are assumed to be varied by temperature changes. The third-order shear deformation shells theory is used to describe the displacement components and Hamilton's principle is employed to derive the motion differential equations. To obtain the results, Navier's method is used as an analytical solution for simply supported boundary condition and the effect of different parameters such as temperature variations, orientation angle, volume fraction of CNTs, different types of elastic foundation and other prominent parameters on the natural frequencies of the structure are considered and discussed in details. Design more functional structures subjected to multi-physical fields is of applications of this study results.