• 한국전기전자재료학회논문지
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• 제29권10호
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• pp.613-619
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• 2016

The aim of this study is to improve of dielectric properties using epoxy/nano alumina composites with adding glycerol diglycidyl ether (GDE:1,2 g). This paper deals with the effects of dielectric properties(${\epsilon}^{\prime}_r$ and $tan{\delta}$) for epoxy/nano alumina contents (1,3 phr) and GDE addition (1,2 g)composites. 5 kinds specimen were prepared with containing epoxy resins, epoxy nano alumina composites. Average particle size of nano used were 30 nm. The nano alumina used were gamma phase particles of spherical shape. The suppression of epoxy chain motion by addition of nano alumina+GDE decreased dielectric loss and relative permittivity magnitude.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1220-1223
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• 2009

The effect of silver (Ag) nano-particles on OLEDs was investigated by using a finite difference time domain (FDTD) tool. The proposed OLEDs employed Ag nanoparticles thermally deposited in a high vacuum on a cathode. The emission rate of the exciton was improved by 1.8 fold compared to the conventional OLEDs without Ag nano-particles. Less spacing between the dipole source and the Ag nano-particles resulted in a larger emission rate of the exciton in the OLED with nano-particles. The size of the Ag nano-particles was proportional to the emission rate of the exciton in a range of nano-meter scale of nano-particles. The enhancement of the emission rate of the exciton due to Ag nano-particles caused the improvement in the efficiency of the proposed OLED.

• Advances in nano research
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• 제5권2호
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• pp.99-111
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• 2017

Nano particles have been gaining increasing attention and applied in many fields to fabricate new materials with novel functions due to their unique physical and chemical properties. In the present study two nano materials, namely nano silica (NS) and nano clay metakaolin (NMK) were partially replaced with ordinary Portland cement (OPC). The replacement level was varied from 0.5 to 2.0% in OPC and blended in cement mortar with a water cement ratio of 0.40. Mechanical property studies and durability experiments such as compressive strength, tensile strength, water absorption, depth of chloride penetration test. Nano silica was synthesized from rice husk ash and analyze the size using particle size analyzer. The results indicate that the compressive and tensile strength of the cement mortars containing nano materials were higher strength compared to the plain mortar with the same water cement ratio.

• 한국재료학회지
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• 제12권10호
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• pp.784-790
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• 2002

For mass product of nanocrystalline ZnO ultrafine powders, self-sustaining combustion process(SCP) and ultrasonic spray combustion method(USCM) were applied at the same time. Ultrasonic spray gun was attached on top of the vertical type furnace. The droplet was sprayed into reaction zone of the furnace to form SCP which produces spherical shape with soft agglomerate crystalline ZnO particles. To characterize formed particles, fuel and oxidizing agent for SCP were used glycine and zinc nitrate or zinc hydroxide. Respectively, with changing combustion temperature and mixture ratio of oxidizing agent and fuel, the best ultrasonic spray conditions were obtained. To observe ultrasonic spray effect, two types of powder synthesis processes were compared. One was directly sprayed into furnace from the precursor solution (Type A), the other directly was heated on the hot plate without using spray gun (Type B). Powder obtained by type A was porous sponge shape with heavy agglomeration, but powder obtained using type B was finer primary particle size, spherical shape with weak agglomeration and bigger value of specific surface area. 9/ This can be due to much lower reaction temperature of type B at ignition time than type A. Synthesized nanocrystalline ZnO powders at the best ultrasonic spray conditions have primary particle size in range 20~30nm and specific surface area is about 20m$^2$/g.

• Journal of Magnetics
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• 제13권4호
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• pp.149-152
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• 2008

In this report, we present the results of a study on the effects of the particle size on the properties of the Prussian blue (PB) analog $Na_xMn_y[Fe(CN){_6}]$. A novel synthesis method of the $Na_xMn_y[Fe(CN){_6}]$ nano-particles using an organic solvent, formamide, is employed. The size of the PB particles is found to be 100-150 nm for the samples prepared in the formamide solvent, which is much smaller than that of the samples prepared using water only. The broadening of the X-ray diffraction peaks of the nano-sized PB samples is attributed to the lattice disorder and a dramatic reduction in the particle size. The compositions of the samples are confirmed by an energy-dispersive X-ray analysis (EDAX), and the result proves that the samples are actually $Na_xMn_y[Fe(CN){_6}]$ Prussian blue. The UV-vis spectra show a broad intervalence charge-transfer (CT) band in the visible region between 400 and 700 nm, and the absorption decreases abruptly in the green region for the nano-sized PB sample. A divergence between the field cooled (FC) and zero field cooled (ZFC) magnetization curves is observed for the nano-sized PB sample at 11 K, indicating that nanoparticles in the sample are single domain superparamagnets with a blocking temperature of 11 K. Our results reveal that the nano-sized PB samples show significantly different optical and magnetic properties than those of the bulk PB samples.

• Journal of Magnetics
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• 제21권3호
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• pp.308-314
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• 2016

Cobalt-, zinc-, and nickel-zinc-substituted nano-size manganese ferrite powders, $MnFe_2O_4$, $Mn_{0.8}Co_{0.2}Fe_2O_4$, $Mn_{0.8}Zn_{0.2}Fe_2O_4$ and $Mn_{0.8}Ni_{0.1}Zn_{0.1}Fe_2O_4$, were fabricated using a sol-gel method, and their crystallographic and magnetic properties were subsequently studied. The $MnFe_2O_4$ ferrite powder annealed at temperatures above 523 K exhibited a spinel structure, and the particle size increased as the annealing temperature increased. All ferrites annealed at 773 K showed a single spinel structure, and the lattice constants and particle size decreased with the substitution of Co, Zn, and Ni-Zn. The $M{\ddot{o}}ssbauer$ spectrum of the $MnFe_2O_4$ ferrite powder annealed at 523 K only showed a doublet due to its superparamagnetic phase, and the $M{\ddot{o}}ssbauer$ spectra of the $MnFe_2O_4$, $Mn_{0.8}Co_{0.2}Fe_2O_4$, and $Mn_{0.8}Zn_{0.2}Fe_2O_4$ ferrite powders annealed at 773 K could be fitted as the superposition of two Zeeman sextets due to the tetrahedral and octahedral sites of the $Fe^{3+}$ ions. However, the $M{\ddot{o}}ssbauer$ spectrum of the $Mn_{0.8}Ni_{0.1}Zn_{0.1}Fe_2O_4$ ferrite powder annealed at 773 K consisted of two Zeeman sextets and one quadrupole doublet due to its ferrimagnetic and paramagnetic behavior. The area ratio of the $M{\ddot{o}}ssbauer$ spectra could be used to determine the cation distribution equation, and we also explained the variation in the $M{\ddot{o}}ssbauer$ parameters by using this cation distribution equation, the superexchange interaction and the particle size. Relative to pure $MnFe_2O_4$, the saturation magnetizations and coercivities were larger in $Mn_{0.8}Co_{0.2}Fe_2O_4$ and smaller in $Mn_{0.8}Zn_{0.2}Fe_2O_4$, and $Mn_{0.8}Ni_{0.1}Zn_{0.1}Fe_2O_4$. These variations could be explained using the site distribution equations, particle sizes and magnetic moments of the substituted ions.

• 접착 및 계면
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• 제18권1호
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• pp.25-32
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• 2017

본 연구는 디스플레이 모듈 접합 공정에 적용하기 위해 자외선 경화형 아크릴계 점착제(PSA)에 실리카 나노 입자를 함량별로 첨가하여 실크 스크린 인쇄성 평가를 실시하였고, 유변학적 성질이 인쇄성 및 점착력에 미치는 영향을 고찰하고자 하였다. 점착제(PSA) 중합을 위한 기본 처방으로 2-ethylhexyl acrylate(2-EHA)와 acrylic acid(AA)를 93:7 비율로 고정하고 butyl acylate(BA), 2-hydroxyethyl acrylate(2-HEA)를 첨가하였다. 추가로 나노 입자는 친수성 및 소수성을 가지는 AEROSIL R974 및 AEROSIL 200을 각각 사용하였다. 나노 입자 함량이 4 또는 7 phr 이상 사용함에 따라 G', ${\eta}^*$ 값이 급격히 증가하였으며, 친수성 나노 입자 AEROSIL 200을 7 phr 이상 첨가했을 때에는 스크린 인쇄 시 투과성이 저하되었다. 점착력은 나노 입자 함량이 증가할수록 감소되는 경향을 보였으며, 친수성인 AEROSIL 200의 경우 점착력이 더욱 저하됨을 알 수 있었다.

• 대한화장품학회지
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• 제39권1호
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• pp.55-63
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• 2013

경피흡수 증진의 수단으로 나노에멀젼의 화장품 응용이 관심의 대상이 되고 있다. 본 연구에서는 저에너지 유화법으로 제조된 나노에멀젼 구성 원료들의 조성을 달리하여 안정성을 확인해 보고자 하였다. 시간 경과에 따른 나노에멀젼의 입자 크기 측정을 통한 안정성 실험 결과, 폴리올을 수상에 첨가한 경우 에탄올상 첨가에 비해 안정성이 크게 증가하였다. 에탄올상의 수상에 대한 첨가속도는 입자 크기나 안정성에 큰 영향이 없었다. 오일의 종류에 따라서도 안정성에는 영향이 없었으나 초기에 형성되는 입자 크기는 오일의 분자량과 polarity에 상관관계를 보이는 것으로 생각되었다. 폴리올의 종류에 따른 안정성과 초기 입자 크기는 1,2 헥산디올을 제외하고는 유사한 경향을 보였다. 오일과 계면활성제 농도 변화는 제조된 나노에멀젼의 초기 입자 크기에는 영향을 주었으나 시간 경과에 따른 변화는 없었다. 에탄올의 농도 변화는 초기 입자 크기와 안정성에 큰 영향을 미치는 것으로 관찰되었다.

• 디지털융복합연구
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• 제13권4호
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• pp.369-375
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• 2015

본 연구에서는 Tween 80/Span 80의 유화계에서, PIC(Phase Inversion Composition) 방법으로, 80 oC에서 화장품용 오일의 나노에멀젼 형성 가능성과 오일의 구조에 따른 나노에멀젼의 안정성에 대하여 평가하였다. 탄화수소 계열의 LP 70, Isopar H 및 Pripure 3759는 모두 입도 분포가 40 nm 내외의 안정한 나노에멀젼을 형성하였다. 직쇄 구조의 실리콘 오일은 불안정한 에멀젼을 형성하였으나 환상 또는 짧은 사슬의 실리콘 오일은 안정한 나노에멀젼을 형성하였다. 에스테르 오일류에서는 분자량이 증가함에 따라 입도가 증가하였고 분자량이 약 450 이상에서는 안정한 나노에멀젼을 얻을 수 없었다. 오일의 친수성과 친유성을 고려하여 계산하는 요구 HLB (Hydrophilic Lipophilic Balance) 값에 대한 나노에멀젼의 입도는 HLB 값이 8-10 정도 범위에서 가장 입도가 작았다.

• 한국재료학회지
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• 제23권2호
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• pp.89-97
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• 2013

The study of grinding behavior characteristics on aluminum powders and carbon nano tubes (CNTs) has recently gained scientific interest due to their useful effect in enhancing advanced nano materials and components, which significantly improves the property of new mechatronics integrated materials and components. We performed a series of dry grinding experiments using a planetary ball mill to systematically investigate the grinding behavior during Al/CNTs nano composite fabrication. This study focused on a comparative study of the various experimental conditions at several variations of rotation speeds, grinding time and with and without CNTs. The results were monitored for the particle size distribution, median diameter, crystal structure from XRD pattern and particle morphology at a given grinding time. It was observed that pure aluminum powders agglomerated with low rotation speed and completely enhanced powder agglomeration. However, Al/CNTs composites were achieved at maximum experiment conditions (350 rpm, 60 min.) of this study by a mechanical alloy process for Al/CNTs mixed powders because the grinding behavior of Al/CNTs composite powder was affected by addition of CNTs. Indeed, the powder morphology and crystal size of the composite powders changed more by an increase of grinding time and rotation speed.