• 제목/요약/키워드: dispersion phenomenon

검색결과 98건 처리시간 0.025초

기상자료에 따른 대기오염확산 민감도평가 -대구성서산업단지에 대한 사례연구- (Sensitivity of Air Pollutants Dispersion According to the Selection of Meteorological Data - Case of Seongseo Industrial Complex of Daegu -)

  • 박명희;김해동;박미영
    • 한국환경과학회지
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    • 제14권2호
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    • pp.141-156
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    • 2005
  • The importance of atmospheric conditions for the assessment of an air pollution situation has been demonstrated by their influence on the various compartments of an air pollution system, comprising all stages from emission to effects. Especially, air pollutants dispersion phenomenon are very sensitive according to wind data. But the discussions of how to apply representative meteorological data in air pollution dispersion model are not frequent in Korean environmental assessment processes. In this study, we investigated the difference of air pollutants dispersion phenomenon using U.S EPA ISCLT3 model according to applying the different meteorological data observed at two points for Seongseo industrial complex of Daegu. Two points are the spot site of Seongseo industrial complex and Daegu meteorological observatory. The winds speed of the spot site were smaller than those of Daegu meteorological observatory. In the winter season, the differences came to about $64\%$ for the period$(I\;February\;2001\~31\;January\;2002)$. Wind directions were also fairly different at two points. The air pollutants dispersion phenomenon estimated from our numerical experiments were also fairly different owing to the meteorological conditions at two points.

PMD Effect on the Clock-based Optimum Dispersion Compensation Monitoring Technique

  • Kim, Sung-Man
    • Journal of the Optical Society of Korea
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    • 제13권1호
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    • pp.112-115
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    • 2009
  • We investigate the effect of polarization-mode dispersion (PMD) on the optimum dispersion compensation (ODC) monitoring and nonlinear penalty in optical transmission systems. We report that PMD may reduce the fiber nonlinearity. We also report that the monitoring error of the clock-based ODC monitoring technique decreases after the first-order PMD compensation. A simple explanation of this phenomenon is shown.

인간의 인지능력 기반의 행동특성이 반영된 분산대피에 관한 연구 (A Study for dispersion evacuation by behavioral characteristics based on human cognitive abilities)

  • 장재순;이동호
    • 대한안전경영과학회지
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    • 제14권3호
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    • pp.159-166
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    • 2012
  • A*algorithm is highly useful to search the shortest route to the destination in the evacuation simulation. For this reason, A*algorithm is used to evaluate the evacuation experiment by the computer simulation. However there are some problems to analyze the outcome in relation to the reality. Because all the people in the building are not well-informed of the shortest route to the exit. And they will not move to the disaster spot though it is shortest route to the exit. Therefore, evacuation simulation program based on A*algorithm raise a problem of bottleneck phenomenon and dangerous result by damage surrounding the disaster spot. The purpose of this research is to prove the necessity for dispersion evacuation simulation by Multi agent system to solve the problems of the existing evacuation simulation program based on A*algorithm.

수리 모형실험을 통한 오염물질의 희석확산산에 관한 연구 (A Study on the Dilution-Dispersion of Pollutant by Hydraulic Model)

  • 박정은
    • 물과 미래
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    • 제16권4호
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    • pp.237-243
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    • 1983
  • 본 연구는 수리모형 실험을 통하여 지류로부터 유입 된 오염원이 합류후에 여하히 의석확산하는 가에 대하여 규명하였다. 본류와 지류의 유량을 변화시키면서 정성적인 확산경향, 유황, 유속, 수리적인 특성을 관찰하였다. 희석확산의 결과는 오염원으로부터의 거리 및 오염의 진행시간에도 많은 영향을 받으나 무엇보다도 그 지점의 유체의 유속이 빠를수록 그리고 유량비가 클수록 오염물질의 희석확산의 효과는 크게 나타났다. 또한, 유속이 커질수록 종방향의 확산속도는 상대적으로 증가하고 횡방향의 확산속도는 감소된다. 이는 속도 분포에 의한 확산이 커지기 때문인 것으로 사료된다.

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EFFECT OF FLOW UNSTEADINESS ON DISPERSION IN NON-NEWTONIAN FLUID IN AN ANNULUS

  • NAGARANI, P.;SEBASTIAN, B.T.
    • Journal of applied mathematics & informatics
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    • 제35권3_4호
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    • pp.241-260
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    • 2017
  • An analysis is made to study the solute transport in a Casson fluid flow through an annulus in presence of oscillatory flow field and determine how this flow influence the solute dispersion along the annular region. Axial dispersion coefficient and the mean concentration expressions are calculated using the generalized dispersion model. Dispersion coefficient in oscillatory flow is found to be a function of frequency parameter, Schmidt number, and the pressure fluctuation component besides its dependency on yield stress of the fluid, annular gap and time in the case of steady flow. Due to the oscillatory nature of the flow, the dispersion coefficient changes cyclically and the amplitude and magnitude of the dispersion increases initially with time and reaches a non - transient state after a certain critical time. This critical value varies with frequency parameter and independent of the other parameters. It is found that the presence of inner cylinder and increase in the size of the inner cylinder inhibits the dispersion process. This model may be used in understanding the dispersion phenomenon in cardiovascular flows and in particular in catheterized arteries.

유도 초음파 신호 분석을 위한 적응 단시간 푸리에 변환 (Adaptive Short-time Fourier Transform for Guided-wave Analysis)

  • 홍진철;선경호;김윤영
    • 한국소음진동공학회논문집
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    • 제15권3호
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    • pp.266-271
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    • 2005
  • Although time-frequency analysis is useful for dispersive wave analysis, conventional methods such as the short-time Fourier transform do not take the dispersion phenomenon into consideration in the tiling of the time-frequency domain. The objective of this paper is to develop an adaptive time-frequency analysis method whose time-frequency tiling is determined with the consideration of signal dispersion characteristics. To achieve the adaptive time-frequency tiling, each of time-frequency atoms is rotated in the time-frequency plane depending on the local wave dispersion. To carry out this adaptive time-frequency transform, dispersion characteristics hidden in a signal are first estimated by an iterative scheme. To examine the effectiveness of the present method, the flexural wave signals measured in a plate were analyzed.

유도 초음파 신호 분석을 위한 적응 단시간 푸리에 변환 (Adaptive Short-time Fourier Transform for Guided-wave Analysis)

  • 선경호;홍진철;김윤영
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2004년도 추계학술대회논문집
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    • pp.606-610
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    • 2004
  • Although time-frequency analysis is useful for dispersive wave analysis, conventional methods such as the short-time Fourier transform do not take the dispersion phenomenon into consideration in the tiling of the time-frequency domain. The objective of this paper is to develop an adaptive time-frequency analysis method whose time-frequency tiling is determined with the consideration of signal dispersion characteristics. To achieve the adaptive time-frequency tiling, each of time-frequency atoms is rotated in the time-frequency plane depending on the local wave dispersion. To carry out this adaptive time-frequency transform, dispersion characteristics hidden in a signal are first estimated by an iterative scheme. To examine the effectiveness of the proposed method, the flexural wave signals measured in a plate were analyzed.

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도로 안전성 확보를 위한 안개 제거 기술에 대한 실험적 연구 (An Experimental Study on the Fog Dispersion Technique for Road Safety)

  • 김성연;진성욱;제영완;김윤제
    • 자동차안전학회지
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    • 제13권3호
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    • pp.13-19
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    • 2021
  • Fog is a phenomenon caused by condensation of water vapor in the atmosphere, which is when very fine drops of water float in the atmosphere and the distance of visible is less than 1km. Fog dispersion technology is a technology that removing or weakening fog by using artificial methods to reduce damage caused by fog. It is applied differently depending on the temperature of fog generation rather than the cause of fog. This study conducted an experimental study on the fog dispersion mechanism in order to minimize damage caused by fog on the road, and studied two methods of over-cooling dispersion using solid-carbon-dioxide as a dissipated particle and dissipating fog particles through thermal acoustic waves. As a result the two methods proved experimentally that were capable of dissipating fog.

Dielectric Relaxation in Electrooptical Switching of Nematics

  • Lavrentovich, Oleg D.;Wonderly, Hugh;Gu, Mingxia;Shiyanovskii, Sergei V.
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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    • pp.1283-1285
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    • 2008
  • We describe how the phenomenon of dielectric dispersion in nematic liquid crystals influences the director dynamics and thus the switching speed of nematic-based displays.

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