• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.927-929
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• 2014

MRE(Magneto-rheological Elastomer) is a material which shows reversible and various modulus in magnetic field. Comparing to conventional rubber vibration isolator, MREs are able to absorb broader frequency range of vibration. These characteristic phenomena result from the orientation of magnetic particle (i.e., chain-like formation). Magnetic reactive powder(MRP), having rapid magnetic reaction, was selected as a magnetic particle to give magnetic field reactive modulus. The mechanical properties of manufactured MREs were measured with the application of magnetic field. The analysis of MR effect was carried out by FFT analyzer with various induced current. As induced magnetic field intensity increased and coated with MRP, increment of MR effect was observed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.288-291
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• 2014

MRE(Magneto-rheological Elastomer) is a material which shows reversible and various modulus in magnetic field. Comparing to conventional rubber vibration isolator, MREs are able to absorb broader frequency range of vibration. These characteristic phenomena result from the orientation of magnetic particle (i.e., chain-like formation) in rubber matrix. In this study, Silicon was used as a matrix in order to manufacture MREs. Magnetic reactive powder(MRP), having rapid magnetic reaction, was selected as a magnetic particle to give magnetic field reactive modulus. The mechanical properties of manufactured MREs were measured with the application of magnetic field. The analysis of MR effect was carried out by FFT analyzer with various induced magnetic field. As the addition of CIP and induced magnetic field intensity increased, increment of MR effect was observed.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.791-794
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• 2008

MRE(Magneto-rheological Elastomer) is a material which shows reversible and various modulus in magnetic field. Comparing to conventional rubber vibration isolator, MREs are able to absorb broader frequency range of vibration. These characteristic phenomena result from the orientation of magnetic particle (i.e., chain-like formation) in rubber matrix. In this study, NR was used as a matrix in order to manufacture MREs. Magnetic reactive powder(MRP), having rapid magnetic reaction, was selected as a magnetic particle to give magnetic field reactive modulus. The mechanical properties of manufactured MREs were measured without the application of magnetic field. The results showed that the tensile property and resilience were decreased while the hardness was increased with the addition of CIP. The analysis of MR effect was carried out by FFT analyzer with various magnetic flux. As the addition of MRP and magnetic flux increased, increment of MR effect was observed.

• Elastomers and Composites
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• v.51 no.2
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• pp.113-121
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• 2016

Magneto-rheological elastomer (MRE) is a material which shows reversible and various modulus under magnetic field. Comparing to conventional rubber vibration isolator, MREs are able to absorb broader frequency range of vibration. These characteristic phenomena result from the orientation of magnetic particle (i.e., chain-like formation) in rubber matrix. In this study, silicone rubber was used as a matrix of MREs. Carbonyl iron particle (CIP) was used to give magnetic field reactive modulus of MRE. The surface of the CIP was modified with chemical reactants such as silane coupling agent and poly(glycidyl methacrylate), to improve interfacial adhesion between matrix and CIP. The mechanical properties of MREs were measured without the application of magnetic field. The results showed that the tensile strength was decreased while the hardness was increased with the addition of CIP. Also, surface modification of CIP resulted in the improvement of physical properties of MRE, but the degree of orientation of CIP became decreased. The analysis of MR effect was carried out using electromagnetic equipment with various magnetic flux. As the addition of CIP and magnetic flux increased, increment of MR effect was observed. Even though the surface modification of CIP gave positive effect on the mechanical properties of MRE, MR effect was decreased with the surface modification of CIP due to decrease of CIP orientation. Throughout this study, it was found that the loading amounts of CIP affected the mechanical properties of MRE, and surface property of CIP was an important factor on MR effect of MRE.

• Korean Journal of Metals and Materials
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• v.50 no.1
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• pp.78-85
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• 2012

Aluminum nitride(AlN) is a compound (III-V group) of hexagonal system with a crystal structure. Its Wurzite phase is a very wide band gap semiconductor material. It has not only a high thermal conductivity, a high electrical resistance, a high electrical insulating constant, a high breakdown voltage and an excellent mechanical strength but also stable thermal and chemical characteristics. This study is on the preferred orientation characteristics of AlN thin films by reactive evaporation using $NH_3$. We have manufactured an AlN thin film and then have checked the crystal structure and the preferred orientation by using an X-ray diffractometer and have also observed the microstructure with TEM and AlN chemical structure with FT-IR. We can manufacture an excellent AlN thin film by reactive evaporation using $NH_3$ under 873 K of substrate temperature. The AlN thin film growth is dependent on Al supplying and $NH_3$ has been found to be effective as a source of $N_2$. However, the nuclear structure of AlN did not occur randomly around the substrate a particle of the a-axis orientation in fast growth speed becomes an earlier crystal structure and is shown to have an a-axis preferred orientation. Therefore, reactive evaporation using $NH_3$ is not affected by provided $H_2$ amount and this can be an easy a-axis orientation method.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.6.2-6.2
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• 2009

Nanostructured materials arecurrently receiving much attention because of their unique structural andphysical properties. Research has been stimulated by the envisagedapplications for this new class of materials in electronics, optics, catalysisand magnetic storage since the properties derived from nanometer-scalematerials are not present in either isolated molecules or micrometer-scalesolids. This study presents the experimental results derived fromthe various functional materials processed in nano-scale using pulsed laserablation, since those materials exhibit new physical phenomena caused by thereduction dimensionality. This presentation consists of three mainparts to consider in pulsed laser ablation (PLA) technique; first nanocrystallinefilms, second, nanocolloidal particles in liquid, and third, nanocoating fororganic/inorganic hybridization. Firstly, nanocrystalline films weresynthesized by pulsed laser deposition at various Ar gas pressures withoutsubstrate heating and/or post annealing treatments. From the controlof processng parameters, nanocystalline films of complex oxides and non-oxidematerials have been successfully fabricated. The excellentcapability of pulsed laser ablation for reactive deposition and its ability totransfer the original stoichiometry of the bulk target to the deposited filmsmakes it suitable for the fabrication of various functionalmaterials. Then, pulsed laser ablation in liquid has attracted muchattention as a new technique to prepare nanocolloidal particles. Inthis work, we represent a novel synthetic approach to directly producehighly-dispersed fluorescent colloidal nanoparticles using the PLA from ceramicbulk target in liquid phase without any surfactant. Furthermore, novel methodbased on simultaneous motion tracking of several individual nanoparticles isproposed for the convenient determination of nanoparticle sizedistributions. Finally, we report that the GaAs nanocrystals issynthesized successfully on the surface of PMMA (polymethylmethacrylate)microspheres by modified PLD technique using a particle fluidizationunit. The characteristics of the laser deposited GaAs nanocrytalswere then investigated. It should be noted that this is the first successfultrial to apply the PLD process nanocrystals on spherical polymermatrices. The present process is found to be a promising method fororganic/inorganic hybridization.