• Title/Summary/Keyword: Stable surface

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Monitoring of III-V semiconductor surface by In-situ Surface PhotoAbsorption

  • Kim, T. J.;Kim, Y. D.;H. Hwang;E. Yoon
    • Journal of the Korean Vacuum Society
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    • v.12 no.S1
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    • pp.79-82
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    • 2003
  • We present the investigation on P- and As-desorption process from the (001) InP surface in metal organic chemical vapor deposition using surface photoabsorption (SPA). The monochromatic SPA signal showed rapid initial increase to reach In-stabilized surface value after $PH_3$ was turned off, but in case of As-desorption, the signal showed clear existence of a metastable state after the $AsH_3$ was turned off. The SPA spectra at each stable surfaces were taken to confirm the interpretation. This result indicates that the As-desorption process should be understood as a two-step process, in contrast to P-desorption of one-step process.

A Study on Canine Body Surface Temperature (개의 體熱에 대한 연구)

  • 서지민;송근호;이버들;조성남;김덕환;이영원;김명철;조규완;김승호
    • Journal of Veterinary Clinics
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    • v.19 no.2
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    • pp.121-124
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    • 2002
  • This study was performed to examine the distribution of mean body surface temperature in 11 clinically healthy dogs. In stable state, ventral and dorsal part of each individual is scanned by digital infrared thermography. The body surface temperature of dorsocranial(DCr), dorsocaudal(DCd), ventrocranial(VCr) and ventrocaudal(VCd) regions were measured by Region Of Interersts(ROI). The mean body surface temperatures of adult dogs were higher than those of puppies in each regions. In addition mean body surface temperature of the ventral region was higher than that of dorsal region.

Dispersion of Aqueous $Al_2O_3$Suspensions with Electrolytes; Influence of the Counter Ion

  • Cecile Pagnoux;Richard Laucournet;Thierry Chartier;Baumard, Jean-Francois
    • The Korean Journal of Ceramics
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    • v.6 no.3
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    • pp.280-285
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    • 2000
  • The electrolyte, $(HO)_2C_6H_2(SO_3Na)_2H_2O $(Tiron), disperses efficiently alumina powder in aqueous media and stable suspensions with 60 vol% solid loading can be prepared. The strong adsorption of this additive is mainly due to the ability of the molecule to form chelate rings with the particle surface but electrostatic interactions between the surface charge and the anionic dispersant strongly influence the amount of Tiron adsorbed. By using a cationic exchange route to substitute the counter ion which neutralizes the sulfonate groups, new molecules of dispersant have been prepared, either with mineral cations as $Li^+,\; Na+^,\; NH_4^\;+$, or with organic cations as counter ion but organic counter ions lead to less to less viscous suspensions than $Na^+$ in particular when the number of carbon atoms of the aliphatic chain increases from 1 to 3.

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The Effect of Surface Modification with La-M-O (M = Ni, Li) on Electrochemical Performances of Li[Ni0.8Co0.15Al0.05]O2 Cathode

  • Ryu, Jea-Hyeok;Kim, Seuk-Buom;Park, Yong-Joon
    • Bulletin of the Korean Chemical Society
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    • v.30 no.3
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    • pp.657-660
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    • 2009
  • The surface of $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ cathode particle was modified by lanthanum based oxide to improve electrochemical property and thermal stability. The XRD pattern of surface layer was indexed with that of $La_4NiLiO_8$. The discharge capacity of modified electrode was higher than that of pristine sample, specially at fast charge-discharge rate and high cut-off voltage. In the DSC profile of the charged sample, the generation of heat by exothermic reaction was decreased by surface modification. Such enhancement may by attributed to the presence of stable lanthanum based oxide, which effectively suppressd the reaction between electrode and electrolyte on the surface of $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ electrode.

On-Site Conservation of the Underwater Objects Excavated (해저 발굴유물의 현장 보존처리)

  • Moon, Whan-Suk;Kim, Byung-Keun;Yang, Soon-Seok
    • 보존과학연구
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    • s.25
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    • pp.133-150
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    • 2004
  • Once the object has been excavated at underwater condition, it should be subjected to condition that may cause its deterioration. Therefore, it is important that the object immediately keeps stable environment. It means that the object was excavated at underwater and it exposed the deterioration condition, as soon as possible it was not dried on surface, especially metallic and organic material. Iron objects is particularly notorious for rapid disintegration that it kept wet or stored in a stable environment. Ceramics, glass and stone were handled carefully that it prevented physical damage by mishandling. Organic materials of wood, leather, rope, bone must not be allowed to dry out because the creaking, shrinking and warping are well known disintegration. Therefore objects is basis of keeping stable condition in on-site and then it will have to pass through a detailed conservation process in the laboratory.

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Design of a Flexible Planar RFID Tag Antenna with Low Performance Degradation from Nearby Target Objects

  • Choo, Jae-Yul;Ryoo, Jeong-Ki;Choo, Ho-Sung
    • Journal of electromagnetic engineering and science
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    • v.11 no.1
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    • pp.1-4
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    • 2011
  • In this letter, we propose a novel tag antenna that has low performance degradation with nearby dielectric material. We obtained a stable reading performance and a broad matching bandwidth on nearby dielectric materials by employing a T-matching network with thick line width and capacitively slot-loaded arms. We then built the proposed antenna and measured the tag sensitivity to examine the reading characteristics with nearby dielectric materials. The measured results clearly demonstrate stable tag sensitivity with various nearby dielectric materials, such as foam, acrylic-plastic, glass, and ceramic plates. To more closely observe the antenna characteristics with nearby dielectric materials, we also examined the impedance variation and surface current distribution with respect to the dielectric constant of nearby target objects, which ranged from $1{\times}{\varepsilon}_0$ to $16{\times}{\varepsilon}_0$.

Homogeneous and Stable P-Type Doping of Graphene by MeV Electron Beam-Stimulated Hybridization with ZnO Thin Films

  • Song, U-Seok;Kim, Yu-Seok;Jeong, Min-Uk;Park, Jong-Yun;An, Gi-Seok
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.08a
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    • pp.145.1-145.1
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    • 2013
  • A prerequisite for the development of graphene-based field effect transistors (FETs) is reliable control of the type and concentration of carriers in graphene. These parameters can be manipulated via the deposition of atoms, molecules, and polymers onto graphene as a result of charge transfer that takes place between the graphene and adsorbates. In this work, we demonstrate a unique and facile methodology for the homogenous and stable p-type doping of graphene by hybridization with ZnO thin films fabricated by MeV electron beam irradiation (MEBI) under ambient conditions. The formation of the ZnO/graphene hybrid nanostructure was attributed to MEBI-stimulated dissociation of zinc acetate dihydrate and a subsequent oxidation process. A ZnO thin film with an ultra-flat surface and uniform thickness was formed on graphene. We found that homogeneous and stable p-type doping was achieved by charge transfer from the graphene to the ZnO film.

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ON TRANSLATION LENGTHS OF PSEUDO-ANOSOV MAPS ON THE CURVE GRAPH

  • Hyungryul Baik;Changsub Kim
    • Bulletin of the Korean Mathematical Society
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    • v.61 no.3
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    • pp.585-595
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    • 2024
  • We show that a pseudo-Anosov map constructed as a product of the large power of Dehn twists of two filling curves always has a geodesic axis on the curve graph of the surface. We also obtain estimates of the stable translation length of a pseudo-Anosov map, when two filling curves are replaced by multicurves. Three main applications of our theorem are the following: (a) determining which word realizes the minimal translation length on the curve graph within a specific class of words, (b) giving a new class of pseudo-Anosov maps optimizing the ratio of stable translation lengths on the curve graph to that on Teichmüller space, (c) giving a partial answer of how much power is needed for Dehn twists to generate right-angled Artin subgroup of the mapping class group.

Underwater Stability of Surface Chemistry Modified Superhydrophobic WOx Nanowire Arrays

  • Lee, Junghan;Yong, Kijung
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.357.1-357.1
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    • 2014
  • Superhydrophobic WOx nanowire (NW) arrays were fabricated using a thermal evaporation and surface chemistry modification methods by self-assembled monolayer (SAM). As-prepared non-wetting WOx NWs surface shows water contact angle of $163.2^{\circ}$ and has reliable stability in underwater conditions. Hence the superhydrophobic WOx NWs surface exhibits silvery surface by total reflection of water layer and air interlayer. The stability analysus of underwater superhydrophobicity of WOx NWs arrays was conducted by changing hydrostatic pressure and surface energy of WOx NWs arrays. The stability of superhydrophobicity in underwater conditions decreased exponentially as hydrostatic pressure applied to the substrates increased3. In addition, as surface energy decreased, the underwater stability of superhydrophobic surface increased sharply. Specifically, sueprhydrophobic stability increased exponentially as surface energy of WOx NWs arrays was decreased. Based on these results, the models for explaining tendencies of superhydrophobic stability underwater resulting from hydrostatic pressure and surface energy were designed. The combination of fugacity and Laplace pressure explained this exponential decay of stability according to hydrostatic pressure and surface energy. This study on fabrication and modeling of underwater stability of superhydrophobic W18O49 NW arrays will help in designing highly stable superhydrophobic surfaces and broadening fields of superhydrophobic applications even submerged underwater.

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Underwater Stability of Surface Chemically Modified Superhydrophobic W18O49 Nanowire Arrays

  • Lee, Junghan;Yong, Kijung
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.601-601
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    • 2013
  • Superhydrophobic W18O49 nanowire (NW) arrays were synthesizedusing a thermal evaporation and surface chemistry modification methods by self-assembled monolayer (SAM). As-prepared non-wetting W18O49 NWs surface shows water contact angle of $163.2^{\circ}$ and has reliable stability in underwater conditions. Hence the superhydrophobic W18O49 NWs surface exhibits silvery surface by total reflection of water layer and air interlayer. The stability analysus of underwater superhydrophobicity of W18O49 NWs arrays was conducted by changing hydrostatic pressure and surface energy of W18O49 NWs arrays. The stability of superhydrophobicity in underwater conditions decreased exponentially as hydrostatic pressure applied to the substrates increased3. In addition, as surface energy decreased, the underwater stability of superhydrophobic surface increased sharply. Specifically, sueprhydrophobic stability increased exponentially as surface energy of W18O49 NWs arrays was decreased. Based on these results, the models for explaining tendencies of superhydrophobic stability underwater resulting from hydrostatic pressure and surface energy were designed. The combination of fugacity and Laplace pressure explained this exponential decay of stability according to hydrostatic pressure and surface energy. This study on fabrication and modeling of underwater stability of superhydrophobic W18O49 NW arrays will help in designing highly stable superhydrophobic surfaces and broadening fields of superhydrophobic applications even submerged underwater.

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