• 제목/요약/키워드: index of dispersion

검색결과 293건 처리시간 0.03초

농도분산에 근거한 혼합지수 사용의 문제 (On the Problem of Using Mixing Index Based on the Concentration Dispersion)

  • 서용권
    • 대한기계학회논문집B
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    • 제30권8호
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    • pp.796-805
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    • 2006
  • In this study, the problem of using the mixing index as a measure of the mixing performance for a certain flow field has been discussed. The flow model subjected to this study is the two-dimensional unsteady lid-driven cavity flow. The transport equation for the concentration within the cavity was solved by using the finite volume method where the convective terms are discretized with the central difference scheme. It was shown that both the concentration dispersion and the mixing index depend highly on the initial distribution of the concentration, and therefore the mixing index obtained from the concentration dispersion equation loses its universal applicability.

Effect of NCO Index on the Particle Size of Polycarbonate Diol-based Polyurethane Dispersion

  • Kim, Dong-Eun;Kang, Seung-Oh;Lee, Sang-Ho
    • Elastomers and Composites
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    • 제55권1호
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    • pp.20-25
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    • 2020
  • The effect of the isocyanate index (NCO index) on the particle size and particle size distribution of a waterborne polyurethane dispersion (WPUD) with polycarbonate-diol was determined. The WPUDs were prepared using a conventional acetone process with polycarbonate-polyol (Mn = 2028), 4,4'-methylenebis(cyclohexyl isocyanate) (H12MDI), 2,2-bis(hydroxymethyl) propionic acid (DMPA), and dibutyltin dilaurate catalyst. At NCO index values below 1.5, the number average particle diameter of the WPUDs significantly increased with the NCO index, whereas the particle diameter slightly varied at higher NCO indexes. The dependency of the WPUD viscosity on the NCO index exhibited similar behavior to that of the particle size. The relative values of the full width at half maximum of the WPUD particle distribution curves at various NCO indexes were not influenced by the NCO index.

$SiO_2$ 첨가에 따른 알루미네이트 유리의 굴절률 분산 특성 (Refractive Index Dispersion of Aluminate Glasses on the Addition of $SiO_2$)

  • 원종원;정용선;오근호
    • 한국세라믹학회지
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    • 제34권7호
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    • pp.693-698
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    • 1997
  • The refractive index and dispersion in the (100-x)(0.6CaO.0.4Al2O3).xSiO2(x=0~30) glasses were investigated. As the amount of SiO2 increased, the refractive index decreased. The change of refractive index was attributed to the change of the molar refraction rather than the molar volume. When the amount of SiO2 was smaller than 20 mol%, the average electronic transition energy gaps(E0) and the electronic oscillator strengths(Ed) were about 10.9($\pm$0.1) nd 18($\pm$0.5)eV, respectively. However E0 and Ed of the glass (CAS30) with 30 mol% SiO2 increased to 12.63 and 19.89eV, respectively. The similar results was observed in the variation of Abbe Number. Abbe number of the glass in the range of 0~20 mol% SiO2 was about 46 and that of CAS30 increased to 60. The zero-material dispersion wavelength({{{{ lambda }}0) of pure calcium aluminate glass was 1.8 ${\mu}{\textrm}{m}$. As the amount of SiO2 increased, the zero-material dispersion wavelength shifted to a shorter wavelength. {{{{ lambda }}0 of CAS30 was 1.5 ${\mu}{\textrm}{m}$, that is currently using for the optical telecommunication system.

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T7F Model에서 차량군분산계수변화에 따른 민감도분석에 관한 연구 (A Study on Sensitivity Analysis by PDF in T7F Model)

  • 황의진
    • 대한공간정보학회지
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    • 제14권1호
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    • pp.57-63
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    • 2006
  • 본 연구에서는 신호연동화에 관한 기초적인 이론에 대하여 고찰하고 광주시 죽봉로의 광천4거리에서 농성광장에 이르는 3개 교차로를 사례지구로 하여 포화교통류율 및 차량군 분산계수 산정기법들을 적용하여 분산계수에 따른 민감도를 분석하는 과정으로 연구를 진행한 결과 다음과 같은 성과를 얻을 수 있었다. 1. 차량군 분산계수는 0.28-0.33으로 같은 지점의 교차로에서도 관측위치에 따라 상류부보다는 하류부가 더 작은 값을 나타내었다. 2. 차량군지수는 큰 변화를 보였으나 수행지수는 미세한 편차를 보였다. 이는 차량분산계수를 0.34로 설정하여 평가하여도 무리가 없음을 나타내었다. 3. T7F 모형에서 연동화 설계 시 차량분산계수 변화에 따른 수행지수값의 민감도가 미소한 것으로 나타났다.

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도시공원의 경관생태학적 분석-패취의 형태지수와 분산도 분석을 중심으로- (Landscape ecological analysis of urban parks -analysis of index of patch shape and the dispersion of patches-)

  • 김명수;안동만
    • 한국조경학회지
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    • 제23권4호
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    • pp.12-19
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    • 1996
  • Urban parks, as remnant patches, of two older cities and two new towns can be analyzed by a landscape ecological approach. The index of patch shape, the dispersion of patches, the mean edge length, and the mean patch size of parks of each city are ocmpared. The findings of this study are as follows : 1) The mean edge length of urban parks of older cities is longer than that of new towns : Seoul>Suwon>Bundang>Ansan. 2) The mean patch size of urban parks in Seoul is much greater than those of other cities : Seoul> Ansan>Suwon>Bundang. 3) The index of patch shape of urban parks of older cities is greater than that of new towns : Seoul>Suwon>BundangAnsan. 4) The dispersion of patches is in the order of Bundang >Ansan>Seoul>Suwon. The new towns have relatively even distributions of urban parks than older cities. Further research is required to find out the relationship between the index of patch shape and patch interior dynamics.

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Temperature Stabilization of Group Index in Silicon Slotted Photonic Crystal Waveguides

  • Aghababaeian, Hassan;Vadjed-Samiei, Mohammad-Hashem;Granpayeh, Nosrat
    • Journal of the Optical Society of Korea
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    • 제15권4호
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    • pp.398-402
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    • 2011
  • In this paper, we have proposed a principle to design wideband, low dispersion and temperature stabilized slow light structure in slotted photonic crystal waveguide (SPCW). The infiltration of the silicon photonic crystal with polymer will enhance the slow light and increase the group index, whereas the different signs of thermo-optic coefficients of polymer and silicon make the proposed structure stable on temperature variation over $60^{\circ}C$ and improves the group index-bandwidth products of the designed structure. The SPCW structure is modified to maximize the slow light effect and minimize the dependence of the group index and hence the group velocity dispersion to temperature.

Vectran®의 수중 분산 거동에 미치는 계면활성제의 영향(I) - 쿼드라트법을 결합한 수중 분산 거동 평가 - (Effects of Surfactants on Dispersion Behavior of Vectran® in Water - Evaluation of Fibers Dispersion Behavior in Water with Quadrat Analysis -)

  • 강유정;이도현;송선혜;배진석
    • 한국염색가공학회지
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    • 제26권4호
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    • pp.339-346
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    • 2014
  • To give a positive effect on dispersion behavior of high performance fibers $Vectran^{(R)}$ in water with reference to wet-laid nonwoven technology, 9 kinds of sulfonate type anionic surfactants were chosen to study. After dispersion experiment, the number and the area occupied by fibers in each sample were counted and figured to calculate the index of dispersion in conjunction with quadrat analysis. Similar tendency was observed in the results of two experiments. The sample without addition of any surfactant resulted in the most aggregated dispersion behavior. As the length of alkyl group attached to sulfonate increases, the sample shows more dispersed behavior. The sample with the surfactant having the aryl group and the longer alkyl group shows the most dispersed behavior and it can be seen with the naked eye as well.

Dispersion and Nonlinear Properties of Elliptical Air Hole Photonic Crystal Fiber

  • Rao, MP Srinivasa;Singh, Vivek
    • Current Optics and Photonics
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    • 제2권6호
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    • pp.525-531
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    • 2018
  • The effect of eccentricity on dispersion and nonlinear properties of a photonic crystal fiber having elliptical air holes is investigated using a fully vectorial effective index method. It is found that the effective refractive index increases with increase of eccentricity. The dependence of dispersion and nonlinear properties of the PCF on the eccentricity of the air hole is investigated. It is revealed that eccentricity of the air hole affects the zero dispersion wavelength. Further, the nonlinear properties such as mode field area, nonlinear coefficient and self phase modulation of the Photonic crystal fibers are analyzed. The mode field area increases and the nonlinear coefficient decreases with increase in eccentricity. The variation of the self phase modulation with elliptical air hole is also discussed.

염기처리시간에 따른 지르코니아 현탁액의 분산성과 굴절율 변화 (Change of Dispersibility and Refractive Index of Zirconia Suspension Depending on Alkali Treatment Time)

  • 조충희;함동석;이재흥;류주환;이기윤;조성근
    • 한국재료학회지
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    • 제27권1호
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    • pp.1-7
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    • 2017
  • Zirconia nanoparticles were widely used as filler in order to get high refractive index layer. However, dispersion of nanoparticles is difficult due to their agglomeration in solvent. In this study, the dispersibility of the zirconia suspension is promoted by controlling the steric hindrance and electrostatic interactions through the adsorption of PEI according to alkali treatment time. Also, to induce improved dispersibility on suspension, we changed the dispersion conditions variously and fabricated an ink formulation method for the coating layer. Zirconia suspension was characterized by dynamic light scattering (DLS), Zeta potential measurement, Transmission Electron Microscope (TEM) and FT-IR. We were able to confirm that good dispersion of zirconia suspension by alkali treatment and PEI led to high refractive index.

$\lambda=1.55\mu\textrm{m}$에서 계단형, 삼각형 분포-이중클래드 분산보상 광섬유의 설계 (Design of Double-clad, Dispersion-Compensated Fiber at$\lambda=1.55\mu\textrm{m}$ : Step & Triangular Index Profile)

  • 김수아;김창민
    • 전자공학회논문지D
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    • 제34D권11호
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    • pp.54-63
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    • 1997
  • The 1-D finite-element mehtod is applied for designing double-clad otpical fibers with dispersion-compensation capability. design parameters allowing only a $LP_{01}$ single mode are treated and macro-bending loss are taken into consideration. Design parameters are extracted to have the compensation ratio $(L_{SMF}/L_{DCF})$ of 6.2 for core structure with step-index profile, and of 5.2 for core with triangular-index profile.

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