• Journal of the Korean Society for Heat Treatment
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• v.33 no.4
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• pp.185-192
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• 2020

In this study, materials characterization of pure copper and copper based carbon nano-tube composite prepared by powder metallurgy method were investigated. Prior to evaluate materials characterization, spark plasma sintering processing variables such as sintering temperature, pressure, thickness and diameter of compacts was optimized to ensure the microstructure and materials property of pure Cu and Cu-CNT composite. In addition, corrosion behavior of Cu-based CNT composite produced by powder sintering method was investigated. It was confirmed from this study that the corroded surfaces of the composite shows less dissolution compared with pure copper in 3.5 wt% NaCl solution. The measured corrosion current density (I_corr) indicates improved corrosion property of Cu based composite containing small additions of CNTs in chloride containing media. Micro-galvanic activity between Cu and CNT was not observed in given sintering condition.

• Journal of Aerospace System Engineering
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• v.9 no.2
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• pp.13-18
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• 2015

Micro planar type liquid propellant thruster was fabricated by MEMS manufacturing process for micro/nano satellites applications. 90 wt.% hydrogen peroxide was used as propellant and for propellant decomposition, Pt/Al2O3 was used as catalyst. Micro thruster structure was made by 5 photosensitive glasses patterned with thruster component profiles. Objective thrust was 50 mN and required hydrogen peroxide mass flow was 2.1 ml/min, which was supplied by syringe pump and teflon tube in experimental test. Performance test said that average steady thrust was approximately 30 mN, around 60% of objective thrust, and transient time was about 5 sec. It is estimated that extended response time was due to high thermal energy loss of micro scale thruster and low enthalpy input by propellant mass flow.

• Transactions on Electrical and Electronic Materials
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• v.11 no.3
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• pp.106-111
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• 2010

The convergence of significantly different and disparate technologies such as spintronics, carbon nano tube field effect transistors, photon and bio-responsive molecular switches, memristor and memristive systems and metamaterials, coupled with energy scavenging sources are gaining a renewed focus in the quest for new products. This paper will provide an insight into an anticipated technological revolution and will highlight a futuristic Roadmap to capture opportunities that are brought about as the results of formulation of new circuit components basically driven by emergence of nanoscale materials as part of System on System integration. Challenges as the result of new lumped components such as memristor, metamaterial-based lumped components and the like that will challenge the designers' comfort zone will also be discussed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.4
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• pp.338-342
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• 2010

Carbon nanotubes (CNTs) have excellent electrical, chemical stability, mechanical and thermal properties. The MWCNT films were investigated as a transparent electrode for the solar cell, OLED, and field-emission display. MWCNT films were fabricated by air spray method, whose process is quite low-costed, using the multi-walled CNTs solution on glass substrates. Moreover, the most stable film was fabricated when the spraying time was 60 sec. The film that was sprayed with the MWCNT dispersion for 60 sec, has 300nm thick. And its electric resistivity, transmittance rate, mobility and carrier concentration are $6{\times}10^{-2}{\Omega}{\cdot}cm$, 50% at ${\lambda}=550mm$, $4.3{\times}10^{-2}cm^2/V{\cdot}s$ and $2.1{\times}10^{21}cm^{-3}$, respectively. Also, absorption energy of MWCNT films show from 3.9 eV to 4.6 eV. Furthermore, we can use MWCNT films fabricated by the spray method for the transparent electrode.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1059-1064
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• 2003

This paper presents an overview of the mechanical properties of carbon nanotubes. The characteristics of carbon nanotubes were briefly introduced. We then present briefly the experimental techniques used to measure mechanical properties and the results obtained by other researchers. A carbon nanotube is too small to be pulled apart with standard tension devices. Manipulators should be used for mechanical testing. We introduced manipulation methods using nanomanipulators under field-emission scanning-electron microscope.

• Corrosion Science and Technology
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• v.2 no.4
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• pp.197-201
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• 2003

In this study, Ni-P layers were electroplated on the surface of stainless steel in order to investigate the effects of an additive and agitation on their mechanical properties and microstructure. The concentration of the additive in the plating solution increased, the pores formed in the layer decreased, while the residual stress developed in the layers during electroplating increased. Agitation of the solution during electroplating was observed to force to increase local pores in the layer, which lowers its tensile properties. Grain growth was suppressed due to very fine $Ni_3P$ precipitates formed at its grain boundaries during heat treatment at $343^{\circ}C$ for 1 hr in air.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1515-1516
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• 2015

Touch panel 및 Touch screen 등의 투명전극으로 많이 사용되고 있는 ITO(Indium Tin Oxide)나 CNT(Carbon Nano Tube) 등 전도성 박막의 면저항을 쉽고 빠르게 측정하기 위하여 van der Pauw method를 이용한 면저항 측정기를 개발하였다. 이 면저항 측정기는 대면적 시료의 면저항을 측정 할 수 있어 매우 편리하다. 면저항 측정은 주로 Four Point Probe method로 측정하는 것이 일반적이나 본 연구에서는 van der Pauw method를 이용한 측정값과 Four Point Probe method로 측정한 결과를 비교한 결과 1 % 이내에서 일치하였다. 개발된 측정기의 측정 정확도는 지시값의 1.0 % 이하이고, 측정범위는 $2{\Omega}/{\square}{\sim} 5k{\Omega}/{\square}$이다.

• Elastomers and Composites
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• v.51 no.4
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• pp.280-285
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• 2016

The purpose of this study is to get optimum design and operation conditions of the heating rubber roller for laminating process. The cause of performance degradation of heating rubber roller is delamination of rubber on metal tube, rubber aging due to high temperature. We measured the material properties of thermal expansion, thermal conductivity, specific heat and density and analyzed thermal distributions of rubber layer using finite element method. As a result of heat/flow analysis, the density distribution of heating coil must shorten the stabilization time by reducing the temperature deviation on the length direction at the temperature rising section after increasing the density of the area contacting with the laminate film at the center part which is an opposite of the current composition while enabling to maintain the temperature of heater to be consistent while maintaining the temperature deviation to be low when heat loss is created. Finally, we determined optimum heating method of heating rubber roller.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1593-1603
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• 2008

지오텍스타일 튜브의 봉합거동에 대한 이론연구와 실험을 수행하여 효율적인 봉합구조와 합리적인 설계 강도의 결정을 위한 방안을 고찰하였다. 수행 실험은 지오텍스타일 튜브 제품을 형성하기 위해 사용되는 봉합사에 대한 해수조건을 고려하여 내구성 평가와 봉합강도를 개선시키기 위해 다양한 봉합형태에 따른 봉합강도를 평가하여 고찰하였다. 지오텍스타일 튜브의 장기설계강도의 결정에서 지오텍스타일 자체의 강도 감소인자 뿐 아니라 봉합부에서의 여러 감소인자들을 고려하여야 하며 정확히 평가할 수 있는 시험규격의 정립이 요구된다. 봉합사의 강도가 유사한 경우 봉합형태가 봉합강도에 주요한 영향을 미치며, 봉합사의 봉합 후 긴장상태도 실험 중에 영향을 미치는 것으로 확인되었다.

• Corrosion Science and Technology
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• v.15 no.1
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• pp.1-5
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• 2016

Zinc ethyl silicate coatings containing multi walled carbon nanotubes (MWCNTs) were prepared, to which we added spherical and flake shaped zinc particles. The anti-corrosive effects of MWCNTs and zinc shapes on the zinc ethyl silicate coated carbon steel was examined, using electrochemical impedance spectroscopy and corrosion potential measurement. The results of EIS and corrosion potential measurement showed that the zinc ethyl silicate coated with flake shaped zinc particles and MWCNT showed lesser protection to corrosion. These outcomes were in agreement with previous results of corrosion potential and corrosion occurrence.