• Journal of the Korean Society for Precision Engineering
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• 제23권4호
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• pp.14-21
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.637-638
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• 2011

• Transactions of the Korean Society of Mechanical Engineers A
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• 제40권2호
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• pp.139-145
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• 2016

In this study, the moisture related hygroscopic characteristics and mechanical properties of epoxy-clay nanocomposites were investigated by experiments as a function of the weight fraction of nanoclay. The hygroscopic and mechanical properties including the moisture saturation amount, moisture diffusivity, adhesive strength, and tensile properties were obtained by moisture absorption test and various tensile tests, respectively. Also, the molecular dynamics (MD) simulation was devised to study of hygroscopic characteristics of nanocomposites and the results were compared to experimental results as a function of the nanoclay content. It was demonstrated that the proposed MD simulation technique can be successfully used for the prediction of the effects of the nanoclay on the moisture diffusion characteristics.

• Composites Research
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• 제22권5호
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• pp.8-14
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• 2009

Interfacial evaluation of glass fiber reinforced carbon nanotube (CNT)-epoxy nanocomposite was investigated by micromechanical technique in combination with wettability test. The contact resistance of the CNT-epoxy nanocomposite was measured using a gradient specimen, containing electrical contacts with gradually-increasing spacing. The contact resistance of CNT-epoxy nanocomposites was evaluated by using the two-point method rather than the four-point method. Due to the presence of hydrophobic domains on the heterogeneous surface, the static contact angle of CNT-epoxy nanocomposite was about $120^{\circ}$, which was rather lower than that for super-hydrophobicity. For surface treated-glass fibers, the tensile strength decreased dramatically, whereas the tensile modulus exhibited little change despite the presence of flaws on the etched fiber surface. The interfacial shear strength (IFSS) between the etched glass fiber and the CNT-epoxy nanocomposites increased due to the enhanced surface energy and roughness. As the thermodynamic work of adhesion, $W_a$ increased, both the mechanical IFSS and the apparent modulus increased, which indicated the consistency with each other.

• Proceedings of the KSME Conference
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.200-203
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• 2007

Carbon nanotubes (CNTs) have attracted an increasing attention due to their superior mechanical properties and potential application in industries. The strength of CNT has been predicted or calculated through several simulation techniques but actual experiments on stress-strain behavior are rare due to its dimensional limit, nanoscale positioning/manipulation, and instrumental resolution. We have attempted to observe straining responses of a multi-walled carbon nanotube (MWNT) with different growth methods by performing an in-situ tensile testing in a scanning electron microscope. Linear deformation and fracture behaviors of MWNT were successfully observed and its force-displacement curve was also measured from the bending stiffness and displacement of the force sensor and manipulator. We also obtained different tensile load of carbon nanotube with different growth methods.

• Composites Research
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• 제19권6호
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• pp.23-31
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• 2006

We measured mechanical properties, including Young's modulus, effective bending modulus and nominal fracture strength of nanohoneycomb structures using an Atomic Force Microscope(AFM) and a Nano-Universal Testing Machine(UTM). Anodic aluminum oxide(AAO) films are well suited as nanohoneycomb structures because of the simple fabrication process, high aspect ratio, self-ordered hexagonal pore structure, and simple control of pore dimensions. Bending tests were carried out for cantilever structures by pressing AFM tips, and the results were compared with three-point bending tests and tensile tests using a Nano-UTM. One side of the AAO films is clogged by harrier layers, and looks like a face material of conventional sandwich structures. Analysis of this layer showed that it did not influence the bending rigidity, and was just a crack tip. The present results can act as a design guideline in applications of nanohoneycomb structures.

• Journal of the Korean Society of Propulsion Engineers
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• 제20권5호
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• pp.70-76
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• 2016

Tensile and compressive strength tests were conducted to investigate the mechanical characteristics of aluminized paraffin wax fuel for hybrid gas generator applications. Mixtures of 0 wt%, 10 wt% and 30 wt% nano aluminum paraffin coupons as well as 5 wt%, 10 wt% and 15 wt% micro aluminum paraffin coupons were used. The average particle size of 100nm and of $8{\mu}m$ mixed each with microcrystalline paraffin wax(Sasol 0907) were chosen for the base specimens where the tensile strength test followed the ASTM-D638 specimen standard while the compressive strength test followed the ASTM D575-91. It was found that nano based specimens increased both the tensile and compressive strength enhancing the mechanical behavior of paraffin wax whereas the micro based specimens gave still less influential effect.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 한국염색가공학회 2012년도 제46차 학술발표회
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• pp.110-110
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• 2012

아라미드 섬유소재는 고강도, 고내열성의 소재로 다양한 용도전개가 가능하나, 일광 및 부식에 의한 내광성 및 내후성이 급격하게 저하되는 단점이 있다. 자외선의 광화학적 작용에 의해 변퇴, 경화, 취하, 강도저하가 일어나는 단점을 보완하기 위해 내광성 및 내화학성이 우수한 전이금속산화물 소재와의 복합화를 통해 내광성 및 내화학성 개선에 대하여 연구하였다. zinc acetate 수화물과 수산화리튬을 무수에탄올로 용해시킨 용액을 강하게 교반하여 나노 산화아연 졸을 제조하였다. 제조된 나노크기의 zinc oxide 입자의 형상과 입자분포 등 제조특성을 입도분석기, FE-SEM 및 EDS 분석을 통하여 고찰하였으며, 제조된 나노졸을 아라미드 섬유에 침지시켜 Xenon-arc 내후성시험기에서 80시간 동안 노출시켜 노출시간에 따른 물성변화를 분석하였다. 나노졸을 5~20% 픽업으로 패딩한 후 광에 노출된 아라미드의 인장강도는 나노졸을 처리하지 않은 아라미드 섬유보다 20~30% 개선된 인장강도를 나타내었다.

• Composites Research
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• 제37권3호
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• pp.209-214
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• 2024

Graphene oxide (GO), known for its high stiffness, thermal conductivity, and electrical conductivity, is being utilized as a reinforcement in nanocomposite materials. This study evaluates the mechanical properties of epoxy nanocomposites incorporating GO and edge modified GO (E-GO), which has hydroxyl groups substituted only on its edges. GO/E-GO was uniformly dispersed in epoxy resin using ultrasonic dispersion, and mechanical properties were assessed through tensile testing. The results showed that the addition of nanoparticles increased both tensile strength and toughness. The tensile strength of the epoxy without nanoparticles was 74.4 MPa, while the highest tensile strength of 90.7 MPa was observed with 0.3 wt% E-GO. Additionally, the modulus increased from 2.55 GPa to 3.53 GPa with the addition of nanoparticles. Field emission scanning electron microscopy of the fracture surface revealed that the growth of cracks was impeded by the nanoparticles, preventing complete fracture and causing the cracks to split in multiple directions. E-GO, with surface treatment only on the edges, exhibited higher mechanical properties than GO due to its superior dispersion and surface treatment effects. These results highlight the importance of nanoparticle surface treatment in developing high-performance nanocomposite materials.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2004년도 춘계학술대회 논문요약집
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• pp.14-14
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• 2004

전자 공학 분야의 발전으로 인해 작은 구조물을 제작할 수 있는 리소그라피 (lithography) 기술이 급속하게 발전하고 있으며, 보다 작은 구조물에 대한 수요도 빠르게 증가하고 있다. 지난 수십 년간 반도체 분야에 적용 되어온 Moore's law에 의하면, 수년 내에 수십 나노 미터 크기의 특성 길이 (Critical Dimension)를 지닌 구조물을 이용하여 소자가 제작될 것 이 예견되고 있다. 반도체 공정을 응용하여 작은 구조물을 제작하는 기술은, 전자 공학 분야뿐만 아니라 광전자공학(optoelectronics) 분야, 양자 계산(quantum computing) 분야, 양자 계산(quantum computing) 분야, MEMS/NEMS, 바이오 센서(biosensor)분야 등에 다양한 응용성을 가질 것으로 예상된다.(중략)