• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.6
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• pp.403-407
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• 2015

Generally, MWCNT, with thermal, chemical and electrical superiority, is manufactured with CVD (chemical vapor deposition). Using MWCNT, it is comonly used as gas sensor of MOS-FET structure. In this study, in order to repeatedly detect gases, the author had to effectively eliminate gases absorbed in a MWCNT sensor. So as to eliminate gases absorbed in a MWCNT sensor, the sensor was applied heat of 423[K], and in order to observe how the applied heat was diffused within the sensor, the author interpreted the diffusion process of heat, using COMSOL interpretation program. In order to interpret the diffusion process of heat, the author progressed modeling with the structure of MWCNT gas sensor in 2-dimension, and defining heat transfer velocity($u={\Delta}T/{\Delta}x$), accorded to governing equation within the sensor, the author proposed heat transfer mechanism.

• Polymer(Korea)
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• v.39 no.2
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• pp.329-337
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• 2015

In this study, multi-walled carbon nanotubes (MWCNTs) were oxidized with a mixture of nitric acid and sulfuric acid. After oxidation, oxidized MWCNTs were treated with thionyl chloride ($SOCl_2$) and 1,4-butanediol (BD) in sequence at room temperature to introduce hydroxyl groups on the surface of MWCNTs. The prepared MWCNT-OH was silanized with 3-methacryloxypropyltrimethoxylsilane (MPTMS) to make MWCNT-MPTMS. The MWCNT-MPTMS was used as fillers in emulsion polymerization to make MWCNT-MPTMS/PMMA composite particles with 3 kinds of emulsifiers, hexadecyltrimethylammoniumbromide (CTAB) as a cationic, sodium dodecylbenzene sulfonate (SDBS) as an anionic and polyethylene glycol tert-octylphenyl ether (Triton X-114) as a nonionic emulsifier. Morphologies of composite emulsions were confirmed by a particle size analyzer (PSA) and a scanning electron microscope (SEM). Morphologies of emulsion polymerized MWCNT-MPTMS/PMMA with SDBS showed more uniform particle size distribution compared to those of other two emulsifiers used emulsions. MWCNT-MPTMS/PMMA showed $3.4^{\circ}C$ higher $T_g$ compared to pristine MWCNT/PMMA due to covalent bond formation at interface of MWCNT-MPTMS and PMMA.

• Applied Chemistry for Engineering
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• v.19 no.4
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• pp.421-426
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• 2008

Multi-walled carbon nanotube/polystyrene (MWCNT/PS) composites with various MWCNT contents were prepared by using a solution process with an aid of surfactant. Particularly, PS's with 3 different molecular weights (${\bar{M}}_n$ = 101500 g/mole for PS-1, ${\bar{M}}_n$ = 89900 g/mole for PS-2, and ${\bar{M}}_n$ = 85000 g/mole for PS-3) were used in this study. Thermal behavior of these composites was examined by using an oscillator rheometer at $210^{\circ}C$ and $180^{\circ}C$, of above and below the critical flow temperature ($T_{cf}{\sim}195^{\circ}C$) of PS matrix, respectively. The storage and loss modulus, and the complex viscosity of these composites increased with increasing MWCNT content at both temperatures. Largest increases in the frequency-dependent moduli and complex viscosity were observed between 2 wt% and 5 wt% of MWCNTs at $210^{\circ}C$ and $180^{\circ}C$. Only the composite at $210^{\circ}C$ showed the rheological phase transition from a viscous-dominant to an elastic-dominant behavior of the composites at a certain MWCNT content. The MWCNT content at the rheological phase transition of MWCNT/PS composites generally increased with decreasing molecular weight of PS, and was measured to be 3.5 wt% for MWCNT/PS-1, 3.2 wt% for MWCNT/PS-2, and 3.0 wt% for MWCNT/PS-3 composites.

• Journal of Korean Society on Water Environment
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• v.33 no.2
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• pp.211-218
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• 2017

This experiment was carried out with the purpose of testing cadmium adsorption abilities of multi wall carbon nanotube (MWCNT), activated carbon, and synthesized layered double hydroxide (LDH). In the acidic condition, only MWCNT was effective for removing cadmium ion in the aqueous phase while other adsorbents rarely removed it. The MWCNT and cadmium ion adsorption reactions followed pseudo-first order kinetic. When the initial pH value was neutral (pH = 7), cadmium ion was rapidly removed by MWCNT and activated carbon in 4 hr (100% and 99.2%, respectively). Increasing adsorbent dosages affects the pH evolution and cadmium ion removal (0 to 99%). Cytotoxicity test showed that both MWCNT and LDH has low cytotoxic effects on three kind of human cells (A549, HS-294t, and HT-29).

• Journal of Urban Science
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• v.9 no.1
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• pp.1-6
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• 2020

The thermoelectric characteristics of alkali activated slag composites containing multi-walled carbon nanotubes (MWCNT) was investigated in the present study. Three different MWCNT contents and exposed temperatures were considered, and their thermoelectric-related properties and internal structures were analyzed. It was found that the alkali activated slag composite with MWCNT 2.0 wt.% and the exposed temperature of 150℃ were the optimal condition to obtain the highest Seebeck coefficient and power factor. Based on the feasibility study, the extended size thermoelectric module with 130 elements was fabricated, and tested the electricity production capacity. Consequently, the present thermoelectric module produced 30.83 ㎼ of electricity at ∆T=178.4℃.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.772-774
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• 2007

The improvement in the field emission parameters, luminescent uniformity, degradation rate and half life has been observed for the thin-multi wall carbon nanotube (t-MWCNT) composite, after incorporating the Zn nanoparticles. The Zn nanoparticles $(diameter\;{\sim}\;100\;{\pm}15\;nm)$ has been incorporated to synthesize the Zn-t-MWCNT composite.

• Applied Chemistry for Engineering
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• v.22 no.1
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• pp.109-113
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• 2011

${\alpha},{\omega}$-Hydroxypropylpoly(dimethylsiloxane) was prepared from the reaction of a ${\alpha},{\omega}$-hydrogen polydimethylsiloxane with an allyl alcohol. MPE-g-poly(dimethylsiloxane) copolymer (MPES) was prepared from the graft copolymerization of MPE with ${\alpha},{\omega}$-hydroxypropyl group terminated PDMS. MPES/HDPE/EtO-CNT need to varify was prepared from the compounding of MPES, HDPE, and surface treated MWCNT with 4-ethoxybenzoic acid at $180^{\circ}C$. Melting point of the MPES/HDPE/EtO-CNT composite was decreased from 130 to $129^{\circ}C$ as increasing the content of MWCNT 10 to 20 wt% in the composite PTC characteristic of the MPES/HDPE/EtO-CNT composite was appeared at $120^{\circ}C$ as abruptly increasing the electrical resistivity at this temperature. The heighest PTC intensity of MPES/HDPE/EtO-CNT compsite at 10 wt% loading of EtO-CNT was 1.9.

• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.2
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• pp.76-81
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• 2007

A novel multi-layer type micro gas sensor for $NO_X$ detection was designed and fabricated. Micro platform defined as type II-1 in this article for micro gas sensor was fabricated using the MEMS technology to meet the demanding needs of lower power consumption. Nano composite materials were fabricated with nanosized tin oxide powder and $\underline{m}$ulti-$\underline{w}$all $\underline{c}$arbon $\underline{n}$ano $\underline{t}$ube (MWCNT) to improve sensitivity. We investigated characteristics of fabricated multi-layer type micro gas sensor with $NO_2$ concentration variations at constant 2.2 V. Sensitivity (S) of micro gas sensor were observed to increase from 2.9, to 7.4 and 11.2 as concentrations of $NO_2$ gases increased from 2.4 ppm, to 3.6 ppm and 4.9 ppm. When 2.4 ppm of $NO_2$ gas was applied, response time and recovery time of micro gas sensor were recorded as 101 seconds and 142 seconds, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.317-318
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• 2009

In this paper, we observed stretching of carbon nanotube (CNT) aggregates driven by the electric filed in a nematic liquid crystal (LC) medium. The CNT aggregates started to stretch above a threshold filed which is $1.5\;V/{\mu}m$ and the original CNT length which is $1.7{\mu}m$ was stretching up to $19.2\;{\mu}m$ at $3.5\;V/{\mu}m$ electric filed. When the CNT aggregates became to stretching, the width and length of CNT aggregates became narrow and long, respectively. The original morphology of the CNT aggregates was restored upon removal of filed.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.162-167
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• 2006

Nanofluid is a kind of new engineering material consisting of nanoparticles dispersed in base fluid. Nanofluids could have various applications such as magnetic fluids, heat exchanger working fluids, lubricants, drug delivery and so on in present study, various nanoparticles, such as MWCNT (Multi-walled Carbon Nanotube), fullerene, copper oxide, and silicon dioxide are used to produce nanofluids. As base fluids, DI-water, ethylene glycol, oil, and silicon oil are used. To investigate the thermo-physical properties of nanofluids, thermal conductivity and kinematic viscosity are measured. Stability estimation of nanofluid is conducted with UV-vis spectrophoto-meter. In this study, the high pressure homogenizer is the most effective method to produce nanofluid with the prepared nanoparticle and base fluid. Excellently stable nanofluids are produced with the magnetron sputtering system. Thermal conductivity of nanofluid increases with increasing particle volume fraction except water-based fullerene nanofluid which has lower thermal conductivity than base fluid due to its lower thermal conductivity, 0.4 W/mK. The experimental results can't be predicted by Jang and Choi model.