• 한국재료학회지
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• 제21권10호
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• pp.525-531
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• 2011

Two dimensional (2D) arrays of noble metal nanoparticles are widely used in the sensing of nanoscale biological and chemical events. Research in this area has sparked considerable interest in many fields owing to the novel optical properties, e.g., the localized surface plasmon resonance, of these metallic nanoarrays. In this paper, we report successes in fabricating 2D arrays of gold nano-islands using nanosphere lithography. The reproducibility and the effectiveness of the nano-patterning method are tested by means of spin coating and capillary force deposition. We found that the capillary force deposition method was more effective for nanospheres with diameters greater than 600 nm, whereas the spin coating method works better for nanospheres with diameters less than 600 nm. The optimal deposition parameters for both methods were reported, showing about 80% reproducibility. In addition, we characterize gold nano-island arrays both geometrically with AFM as well as optically with UV-VIS spectrometry. The AFM images revealed that the obtained nano-arrays formed a hexagonal pattern of truncated tetrahedron nano-islands. The experimental and theoretical values of the geometric parameters were compared. The 2D gold nano-arrays showed strong LSPR in the absorption spectra. As the nano-islands increased in size, the LSPR absorption bands became red-shifted. Linear dependence of the plasmon absorption maximum on the size of the gold nano-islands was identified through the increment in the plasmon absorption maximum rate for a one nanometer increase in the characteristic length of the nano-islands. We found that the 2D gold nano-arrays showed nearly seven-fold higher sensitivity of the absorption spectrum to the size of the nano-islands as compared to colloidal gold nano-particles.

• International Journal of Precision Engineering and Manufacturing
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• 제8권2호
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• pp.70-74
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• 2007

This paper describes the development of a nano-positioning system for nanoscale science and engineering. Conventional positioning systems, which can be expensive and complicated, require the use of laser interferometers or capacitive transducers to measure nanoscale displacements of the stage. In this study, a new self-displacement sensing (SDS) nano-stage was developed using mechanical magnification of its displacement signal. The SDS nano-stage measured the displacement of its movement using a position-sensitive photodiode (PSPD), a laser source, and a hinge-connected rotating mirror plate. A beam from a laser diode was focused onto the middle of the plate with the rotating mirror. The position variation of the reflected beam from the mirror rotation was then monitored by the PSPD. Finally, the PSPD measured the amplified displacement as opposed to the actual movement of the stage via an optical lever mechanism, providing the ability to more precisely control the nanoscale stage. The displacement amplification process was modeled by structural analysis. The simulation results of the amplification ratio showed that the distance variation between the PSPD and the mirror plate as well as the length L of the mirror plate could be used as the basic design parameters for a SDS nano-stage. The PSPD was originally designed for a total travel range of 30 to 60 mm, and the SDS nano-stage amplified that range by a factor of 15 to 25. Based on these results, a SDS nano-stage was fabricated using principle of displacement amplification.

• 한국재료학회지
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• 제19권1호
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• pp.50-53
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• 2009

Multi-walled carbon nanotubes (MWNTs) were synthesized on different substrates (bare Si and $SiO_2$/Si substrate) to investigate dye-sensitized solar cell (DSSC) applications as counter electrode materials. The synthesis of MWNTs samples used identical conditions of a Fe catalyst created by thermal chemical vapor deposition at $900^{\circ}C$. It was found that the diameter of the MWNTs on the Si substrate sample is approximately $5{\sim}10nm$ larger than that of a $SiO_2$/Si substrate sample. Moreover, MWNTs on a Si substrate sample were well-crystallized in terms of their Raman spectrum. In addition, the MWNTs on Si substrate sample show an enhanced redox reaction, as observed through a smaller interface resistance and faster reaction rates in the EIS spectrum. The results show that DSSCs with a MWNT counter electrode on a bare Si substrate sample demonstrate energy conversion efficiency in excess of 1.4 %.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1328_1329
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• 2009

Nano porous indium tin oxide (ITO) powder was synthesized employing a new route sol-gel combustion hybrid method using Ketjen Black as a fuel. The nano porous ITO powder was composed of $SnCl_4$-98.0% and $In(NO_3)_3{\cdot}XH_2O$-99.999%, produce with a $NH_4OH$ with sol-gel method as a catalyst [1,2]. Crystal structures were examined by powder X-ray diffraction (XRD), and those results show shaper intensity peak at $25.6^{\circ}(2{\Theta})$ of $SnO_2$ by increased sintering temperature. A particle morphology as well as crystal size was investigated by scanning electron microscopy(FE-SEM), and the size of the nano porous powder was found to be in the range of 20~30nm. ITO films could controlled by nano porous powder at various sintering temperature in this paper[3,4]. The sol-gel combustion method was offered simple and effective route for the synthesis of nano porous ITO powder[5].

• Computers and Concrete
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• 제14권2호
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• pp.175-191
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• 2014

In recent years, the emergence of nanotechnology and nanomaterial has created hopes to improve various properties of concrete. Nano silica as one of these materials has been introduced as a cement replacement material for concrete mixture in construction applications. It can modify the properties of concrete, due to high pozzolanic reactions and also making a denser microstructure. On the other hand, it is well recognized that the use of mineral admixtures such as silica fume affects the mechanical properties and durability of cementitious materials. In addition, the superior performance of self-consolidating concrete (SCC) and self-consolidating mortars (SCM) over conventional concrete is generally related to their ingredients. This study investigates the effect of nano silica and silica fume on the compressive strength and chloride permeability of self-consolidating mortars. Tests include compressive strength, rapid chloride permeability test, water permeability, capillary water absorption, and surface electrical resistance, which carried out on twenty mortar mixtures containing zero to 6 percent of nano silica and silica fume. Results show that SCMs incorporating nano silica had higher compressive strength at various ages. In addition, results show that nano silica has enhanced the durability SCMs and reduced the chloride permeability.

• 한국산학기술학회논문지
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• 제11권8호
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• pp.2963-2967
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• 2010

본 논문에서는 일사량과 온도의 조건에 따른 MSX 60 태양광 모듈의 출력을 예측하였다. MATLAB 모의실험을 통하여 온도, 직렬저항 및 일사량 변화를 고려한 2차원, 3차원 I-V 곡선을 구하였으며, 단락전류(Isc) 3.8 A, 개방전압(Voc) 21 V, 최대전력(Pamx) 60W 등의 전기적 파라미터 등을 얻을 수 있었다. 한편, 예측한 결과와 실제 태양광 모듈을 비교하였을 때 모듈의 사양서와 예측 결과 값의 오차율 3 % 이내에 일치함을 보였다.

• 제어로봇시스템학회논문지
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• 제14권5호
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• pp.420-425
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• 2008

PMMA light guiding plate with nano-sized pattern was fabricated using anodized aluminum oxide membrane as a template for nano imprint lithography. Nano-sized pore arrays were prepared by the self-organization processes of the anodic oxidation using the aluminum plate with 99.999% purity. Since the aluminum plate has a rough surface, the aluminum plate with thickness of 1mm was anodized after the pre-treatments of chemical polishing, and electrochemical polishing. The surface morphology of the alumina obtained by the first anodization process was controlled by the concentration of electrochemical solution during the first anodization. The surface morphology of the alumina was also changed according to temperature of the solution during chemical polishing performed after first anodization. The pore widening process was employed for obtaining the one-channel with flat surface and height of the channel because the pores of the alumina membrane prepared by the fixed voltage method shows the structure of two-channel with rough surface. It is shown from SPM results that the nano-sized pattern on PMMA light guiding plate fabricated by nano imprint lithography method was well transferred from that of anodized aluminum oxide template.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.313-313
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• 2012

ZnO and $SnO_2$, well-known wide direct band-gap semiconductors, have been considered as the most promising functional materials due to their highly sensitive gas sensing and excellent optical properties. ZnO/$SnO_2$ epitaxial hetrostructure exhibited unique luminescence properties in contrast with individual tetra-pod ZnO and $SnO_2$ nanostructures. Polycrystalline $SnO_2$-based samples $Zn_xSn_{1-x}O_2$(x=0, 0.01, 0.03, 0.05) were prepared by solid state reaction and eco-friendly hydrothermal techniques. Scanning electron microscopy equipped with electron dispersive x-ray spectra confirms the formation of near stoichiometric $Zn_xSn_{1-x}O_2$ nanorods of diameter ~10 nm. X-ray diffraction analysis revealed the rutile structure, except for x=0.07, which may have a small part of $Zn_2SnO_4$ as a secondary phase.

• Journal of Magnetics
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• 제12권1호
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• pp.7-11
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• 2007

We confirm the validity of the analytic expression for the temperature of the Joule heated nano-wire [C.-Y. You et al. Appl. Phys. Lett. 89, 222513 (2006)] with finite element method. The temperature of the Joule heated nano-wire is essential information for the research of the current induced domain wall movement. The analytic expression includes an adjustable parameter which must be determined. Since the physical origin of the adjustable parameter is simplification of the heat source profile, the validity of the analytic expression must be examined for wide range of the nano-wire structure. By comparison with this analytic expression with the results of full numerical finite element method, the adjustable parameter has been determined. The numerically confirmed adjustable parameter values are in the range of 0.60$\sim$0.69, which is well matched with the theoretically expected one. Furthermore, it is found that the adjustable parameter is a slow varying function of the nano-wire geometry. Based on this numerical confirmation, we can apply the analytic expression for the wide range of the nano-wire geometry with proper adjustable parameters.

• Elastomers and Composites
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• 제34권1호
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• pp.45-52
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• 1999

본 논문에서는 미세 상분리된 블럭 공중합체 박막의 특이상에서 금 입자들이 어떻게 자기응집(self assemble) 되고 잘 배열된 패턴을 형성하는지를 살펴보았다. 본 연구에서는 원통형 모폴로지를 갖는 PS-PB-PS 삼블럭 공중합체(30wt% PS) 박막(${\sim}100nm$)을 0.1wt% 톨루엔 용액으로부터 캐스팅하여 고분자 박막 형판(template)으로 사용하였다. 각각의 상이한 용매 증발조건으로부터 PB matrix내에 수평배열 PS cylinder와 수직 PS cylinder를 함께 갖는 막이 얻어졌다. 블럭 공중합체박막의 표면 및 bulk 몰폴로지를 살펴보기 위하여 단면투과전자현미경(TEM)을 사용하였다. Nano-scale 패턴을 얻기 위하여는 소량의 금입자를 블럭 공중합체 박막상에 증발시켰다. 캐스팅된 상태 그 대로의 박막형판이 사용되어질때 금입자들은 표면 장력이 적은 PB상에 우선적으로 자기응집(self as-semble)하여 비교적 잘 배열된 nano-scale의 패턴을 형성하였다. 그러나 열처리(annealing)에 의하여 표면장력이 적은 PB-rich충이 형성된 후에는 금입자의 자기응집에 의한 패턴은 관찰되지 않았다.