• Title, Summary, Keyword: Dispersion index

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

  • Suh Yong-Kweon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.30 no.8
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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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    • v.55 no.1
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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.

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

  • 원종원;정용선;오근호
    • Journal of the Korean Ceramic Society
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    • v.34 no.7
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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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A Study on Sensitivity Analysis by PDF in T7F Model (T7F Model에서 차량군분산계수변화에 따른 민감도분석에 관한 연구)

  • Hwang, Eui-Jin
    • Journal of Korean Society for Geospatial Information System
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    • v.14 no.1
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    • pp.57-63
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    • 2006
  • The purpose of this study is to correct data on 3 intersection ranging from Kwangchun INT. to Nongsung INT. by the means of VTR recording and site survey and to measure the responsiveness of performance index by diversifying the platoon dispersion factor in signal progression simulation. The results are as follows : 1. The value of platoon dispersion factor was 0.28-0.33. The value in up stream is lower than that of in down stream even on the same intersection. 2. The platoon index showed big changes, though performance index didn't according to platoon dispersion factor. Therefore the value of platoon dispersion factor which is inner variable in T7F can be fixed for 0.34. 3. There was only little divergence in performance index changes according to platoon dispersion factor in designing the progression or T7F model.

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

  • 김명수;안동만
    • Journal of the Korean Institute of Landscape Architecture
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    • v.23 no.4
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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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    • v.15 no.4
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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.

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

  • Kang, Yoo-Jung;Lee, Do-Hyun;Song, Sun-Hye;Bae, Jin-Seok
    • Textile Coloration and Finishing
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    • v.26 no.4
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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.

A Study on the Internet Intrusion Detection and Prediction by IDC (Index Dispersion for Count를 이용한 인터넷에서의 침입탐지예측)

  • Lee, Kyunghee
    • Proceedings of the Korea Information Processing Society Conference
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    • pp.1069-1070
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    • 2009
  • 본 논문에서는 실시간 학습기능을 갖는 다층 신경회로망과 주어지는 인터넷 트래픽 데이터에서의 IDC(Index dispersion for count) 정보를 이용하여 인터넷에서의 공격(침입)을 탐지 예측 할 수 있는 모델을 제안하고 컴퓨터 모의실험을 통한 결과를 보인다.

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Dispersion and Nonlinear Properties of Elliptical Air Hole Photonic Crystal Fiber

  • Rao, MP Srinivasa;Singh, Vivek
    • Current Optics and Photonics
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    • v.2 no.6
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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.