• Title/Summary/Keyword: Nano well

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Comparisons of lasing characteristics of InGaAs quantum-dot and quantum well laser diodes (InGaAs 양자점 레이저 다이오드와 양자우물 레이저 다이오드의 특성 비교)

  • Jung, Kyung-Wuk;Kim, Kwang-Woong;Ryu, Sung-Pil;Cho, Nam-Ki;Park, Sung-Jun;Song, Jin-Dong;Choi, Won-Jun;Lee, Jung-Il;Yang, Hae-Suk
    • Journal of the Korean Vacuum Society
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    • v.16 no.5
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    • pp.371-376
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    • 2007
  • We have investigated the lasing characteristics of the InGaAs quantum dot laser diode (QD-LD) and InGaAs quantum well laser diode (QW-LD) operated at the 980 nm wavelength range. The 980-nm lasers are used as a pumping source for a erbium-doped fiber amplifier (EDFA) and it shows high efficiency in long-haul optical fiber network. We have compared the threshold current density, the characteristic temperature, the optical power and the internal efficiency of QD-LD and QW-LD under a pulsed current condition. The QD-LD shows superior performances to the QW-LD. Further optimization of a LD structure is expected to the superior performances of a QD-LD.

Surface Damage Characteristics of Self-Assembled Monolayer and Its Application in Metal Nano-Structure Fabrication (자기 조립 분자막의 표면파손특성 및 미세 금속 구조물 제작에의 응용)

  • Sung, In-Ha;Kim, Dae-Eun
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.05a
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    • pp.40-44
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    • 2002
  • The motivation of this work is to use SAM(Self-Assembled Monolayer) for developing a rapid and flexible non-photolithographic nano-structure fabrication technique which can be utilized in micro-machining of metals as well as silicon-based materials. The fabrication technique implemented in this work consists of a two-step process, namely, mechanical scribing followed by chemical etching. From the experimental results, it was found that thiol on copper surface could be removed even under a few nN normal load. The nano-tribological characteristics of thiol-SAM on various metals were largely dependent on the native oxide layer of metals. Based on these findings, nano-patterns with sub-micrometer width and depth on metal surfaces such as Cu, Au and Ag could be obtained using a diamond-coated tip.

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Precipitated Calcium Carbonate Synthesis by Simultaneous Injection to Produce Nano Whisker Aragonite

  • Ramakrishna, Chilakala;Thenepalli, Thriveni;Huh, Jae-Hoon;Ahn, Ji Whan
    • Journal of the Korean Ceramic Society
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    • v.53 no.2
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    • pp.222-226
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    • 2016
  • The synthesis of pure calcium carbonate nanocrystals was achieved using a simultaneous injection method to produce nano particles of uniform size. These were characterized using scanning electron microscopy and powder X-ray diffraction. The nano particles were needle-shaped aragonite polymorphs, approximately 100-200 nm in length. The aragonite polymorph of calcium carbonate was prepared using aqueous solutions of $CaCl_2$ and $Na_2CO_3$, which were injected simultaneously into double distilled water at $50^{\circ}C$ and then allowed to react for 1.5 h. The resulting whisker-type nano aragonite with high aspect ratio (30) is biocompatible and potentially suitable for applications in light weight plastics, as well as in the medical, pharmaceutical, cosmetic and paint industries.

Effects of the Ultrafine and Nano-sized Clay on Rheological Behavior of the Matrix of ρ-alumina Bonded Castable

  • Cheon, Sungho;Jun, Byungsei
    • Journal of the Korean Ceramic Society
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    • v.40 no.7
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    • pp.632-636
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    • 2003
  • To prepare the alumina cement free vibrated alumina castable, $\rho$-alumina is employed as a binder material, and nano-sized clay is added to enhance the curing strength and give thixotropic behavior. The rheological behavior of matrix of castable is controlled by investigating the influences of ultrafines, $\rho$-alumina, and nano-sized clay on the viscosity of matrix. The microsilica and ultrafine alumina were added 3 wt% and 4 wt%, respectively to the matrix, which showed that the viscosities tends to be lowest values. The rheological property of the matrix is well established by adding $\rho$-alumina as 8 wt% and clay as 4 wt%. The thixotropic behavior of the $\rho$-alumina bonded castable was appeared by introducing nano-sized clay into the matrix and adjusting the pH near to the PZC of the clay suspension.

Photoluminescence Characteristics of ZnO Nano Needle-like Rods grown by the Hot Wall Epitaxy Method

  • Eom, Sung-Hwan;Choi, Yong-Dae
    • Transactions on Electrical and Electronic Materials
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    • v.8 no.5
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    • pp.191-195
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    • 2007
  • We investigated photoluminescence characteristics of ZnO nano needle-like rods grown on a c-plane $AL_2O_3$ substrate by the hot wall epitaxy method. The nano-rods were vertically well aligned along the ZnO c-axis. The diameters of the ZnO nano-rods ranged from 20 nm to 30 nm and their lengths were between 600 and 700 nm. In the photoluminescence spectrum at 10 K, the exciton emission bound to the neutral donor dominated while defect related emission was weakly observed. With a further increase of temperature, the free exciton emission appeared and eventually became dominant at room temperature.

Production of Nano Powder by Using Transferred Thermal Plasma (이송식 열 플라즈마를 이용한 나노입자 제조)

  • Jo, Tae-Jin;Kim, Heon-Chang;Han, Chang-Suk;Kim, Jwa-Yeon;Kim, Young-Suk
    • Journal of Powder Materials
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    • v.14 no.2 s.61
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    • pp.116-122
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    • 2007
  • It is well known that thermal plasma process has lots of advantages such as high temperature and good quality for synthesis of nano particles. In this research, we attempt the synthesis of nano unitary and composite powder (Ag, Mg-Al, Zr-V-Fe) using transferred thermal plasma. Nano particles of metal alloy, ranging from 20 nm to 150 nm, have been synthesized by this process.

Synthesis of PMMA Plate with Nano-Sized Pattern on Anodized Aluminum Oxide Template (AAO 나노기공을 형틀로 이용한 PMMA 나노패턴 형성 기술)

  • Lee, B.W.;Lee, K.W.;Lee, C.H.;Lee, T.S.;Hong, C.;Chung, Jae-Hoon;Kim, C.K.;Lee, J.H.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.11a
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    • pp.382-383
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    • 2007
  • PMMA plate with nano-sized pattern was synthesized on anodized aluminum oxide template by bluk polymerization method. Anodized aluminum oxide was used as a template to synthesize the PMMA plate with nano-sized pattern. The polymerization of MMA was performed at $75-79^{\circ}C$. It is verified from SPM results that the nano-sized pattern on synthesized PMMA plate was well transferred from that of anodized aluminum oxide template.

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A review of effects of partial dynamic loading on dynamic response of nonlocal functionally graded material beams

  • Ahmed, Ridha A.;Fenjan, Raad M.;Hamad, Luay Badr;Faleh, Nadhim M.
    • Advances in materials Research
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    • v.9 no.1
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    • pp.33-48
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    • 2020
  • With the use of differential quadrature method (DQM), forced vibrations and resonance frequency analysis of functionally graded (FG) nano-size beams rested on elastic substrate have been studied utilizing a shear deformation refined beam theory which contains shear deformations influence needless of any correction coefficient. The nano-size beam is exposed to uniformly-type dynamical loads having partial length. The two parameters elastic substrate is consist of linear springs as well as shear coefficient. Gradation of each material property for nano-size beam has been defined in the context of Mori-Tanaka scheme. Governing equations for embedded refined FG nano-size beams exposed to dynamical load have been achieved by utilizing Eringen's nonlocal differential law and Hamilton's rule. Derived equations have solved via DQM based on simply supported-simply supported edge condition. It will be shown that forced vibrations properties and resonance frequency of embedded FG nano-size beam are prominently affected by material gradation, nonlocal field, substrate coefficients and load factors.

A Carbon Nanotubes-Silicon Nanoparticles Network for High Performance Lithium Rechargeable Battery Anodes

  • Kim, Byung Gon;Shin, Weon Ho;Lim, Soo Yeon;Kong, Byung Seon;Choi, Jang Wook
    • Journal of Electrochemical Science and Technology
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    • v.3 no.3
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    • pp.116-122
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    • 2012
  • As an effort to address the chronic capacity fading of Si anodes and thus achieve their robust cycling performance, herein, we develop a unique electrode in which silicon nanoparticles are embedded in the carbon nanotubes network. Utilizing robust contacts between silicon nanoparticles and carbon nanotubes, the composite electrodes exhibit excellent electrochemical performance : 95.5% capacity retention after 140 cycles as well as rate capability such that at the C-rate increase from 0.1C to 1C to 10C, the specific capacities of 850, 698, and 312 mAh/g are obtained, respectively. The present investigation suggests a useful design principle for silicon as well as other high capacity alloying electrodes that undergo large volume expansions during battery operations.