• Title/Summary/Keyword: Dispersion pattern

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SST Effect upon Numerical Simulation of Atmospheric Dispersion (대기확산의 수치모의에서 SST 효과)

  • 이화운;원경미;조인숙
    • Journal of Korean Society for Atmospheric Environment
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    • v.15 no.6
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    • pp.767-777
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    • 1999
  • In the coastal region air flow changes due to the abrupt change of surface temperature between land and sea. So a numerical simulation for atmospheric flow fields must be considered the correct fields of sea surface temperature(SST). In this study, we used variables such as latent heat flux, sensible heat flux, short and long wave radiation of ocean and atmosphere which exchanged across the sea surface between atmosphere and ocean model. We found that this consideration simulated the more precise SST fields by comparing with those of the observated results. Simulated horizontal SST differences in season were 2.5~4$^{\circ}C$. Therefore we simulated the more precise atmospheric flow fields and the movement and dispersion of the pollutants with the Lagrangian particle dispersion model. In the daytime dispersion pattern of the pollutants emitted from ship sources moved toward inland, in the night time moved toward sea by land/sea breeze criculation. But air pollutants dispersion can be affected by inland topography, especially Yangsan and coastal area because of nocturnal wind speed decrease.

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A Simple CPW-Fed UWB Antenna Design

  • Park, Sang-Yong;Oh, Seon-Jeong;Park, Jong-Kweon
    • Journal of electromagnetic engineering and science
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    • v.10 no.1
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    • pp.13-17
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    • 2010
  • In this paper, we have described a simple CPW-fed UWB antenna for wireless UWB communication. The proposed antenna consists of two symmetrical strips having two steps and CPW feeding. Two techniques(symmetrical structure, two steps) are used to produce good low-dispersion and impedance matching. The proposed UWB antenna has an omni directional radiation pattern, compact size, low dispersion, and low cost.

Fabrication of Functional ZnO Nano-particles Dispersion Resin Pattern Through Thermal Imprinting Process (ZnO 나노 입자 분산 레진의 thermal imprinting 공정을 통한 기능성 패턴 제작)

  • Kwon, Moo-Hyun;Lee, Heon
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.12
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    • pp.1419-1424
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    • 2011
  • Nanoimprint lithography is a next generation lithography technology, which enables to fabricate nano to micron-scale patterns through simple and low cost process. Nanoimprint lithography has been applied in various industry fields such as light emitting diodes, solar cells and display. Functional patterns, including anti-reflection moth-eye pattern, photonic crystal pattern, fabricated by nanoimprint lithography are used to improve overall efficiency of devices in that fields. For these reasons, in this study, sub-micron-scaled functional patterns were directly fabricated on Si and glass substrates by thermal imprinting process using ZnO nano-particles dispersion resin. Through the thermal imprinting process, arrays of sub-micron-scaled pillar and hole patterns were successfully fabricated on the Si and glass substrates. And then, the topography, components and optical property of the imprinted ZnO nano-particles/resin patterns are characterized by Scanning Electron Microscope, Energy-dispersive X-ray spectroscopy and UV-vis spectrometer, respectively.

Dispersion Managed Optical Transmission Links with Artificially Distributed RDPS (RDPS가 인위적으로 분포하는 분산 제어 광전송 링크)

  • Lee, Seong-Real
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2013.10a
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    • pp.975-977
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    • 2013
  • The optimal distribution pattern is induced in the optical link with an artificial distributions of single mode fiber (SMF) lengths and residual dispersion per span (RDPS). It is confirmed that the descending distribution of SMF length and ascending distribution of RDPS are most suitable to compensate for the distorted WDM signals, as the fiber span number is more increased. in the optical link with 10 ps/nm or -10 ps/nm the optimal net residual dispersion (NRD).

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Numerical Analysis of Flow and Pollutant Dispersion over 2-D Bell Shaped Hills

  • Jung, Young-Rae;Park, Keun;Park, Warn-Gyu;Park, Ok-Hyun
    • Journal of Mechanical Science and Technology
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    • v.17 no.7
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    • pp.1054-1062
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    • 2003
  • The numerical simulations of flow and pollutant particle dispersion are described for two-dimensional bell shaped hills with various aspect ratios. The Reynolds-averaged incompressible Navier-Stokes equations with low Reynolds number $\kappa$-$\varepsilon$ turbulent model are used to simulate the flowfield. The gradient diffusion equation is used to solve the pollutant dispersion field. The code was validated by comparison of velocity, turbulent kinetic energy, Reynolds shear stress, speed-up ratio, and ground level concentration with experimental and numerical data. Good agreement has been achieved and it has been found that the pollutant dispersion pattern and ground level concentration have been strongly influenced by the hill shape and aspect ratio, as well as the location and height of the source.

MSSI System with Dispersion-managed Link Configured with Random-inverse Dispersion Maps (랜덤-반전 분산 맵으로 설계된 분산 제어 링크를 갖는 MSSI 시스템)

  • Seong-Real Lee
    • Journal of Advanced Navigation Technology
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    • v.27 no.4
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    • pp.457-462
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    • 2023
  • We proposed a flexible link configuration in a system combining mid-span spectral inversion (MSSI) and dispersion management used for long-distance transmission of high-capacity optical signals such as wavelength division multiplexing signals, and examined specific methods to increase chromatic dispersion and nonlinear distortion compensation effects. The dispersion map proposed to increase the flexibility of dispersion-managed link configuration has a 'random-inverse' structure. That is, in the proposed dispersion map, the residual dispersion per span (RDPS) of each fiber span in the first half section up to the optical phase conjugator is randomly distributed, and the RDPS distribution in the second half section reverses the distribution pattern of the first section. Although the proposed dispersion map has a random distribution of RDPS, it was confirmed that the distortion compensation effect is improved due to the fact that the dispersion profile is symmetrical with respect to the optical phase conjugator. In the dispersion map of the 'random-inverse' configuration, it was also confirmed that the compensation effect of the distorted wavelength division multiplexing signal becomes improved when the magnitude of the RDPS allocated to each fiber span is large.

Primary Dispersion Patterns and Widths of Elements in Altered Granitic Wallrock around the Gold-bearing Quartz Veins at the Mugeug Mine (무극 함금석영맥광상 화강암질모암에서의 원소들의 분산형태와 분산범위)

  • Hwang, In Ho;Chon, Hyo Taek
    • Economic and Environmental Geology
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    • v.27 no.5
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    • pp.451-458
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    • 1994
  • Geochemical studies on gold-bearing quartz veins and granitic wallrocks from the Mugeug mine were carried out in order to investigate primary dispersion patterns of elements and to quantify primary dispersion widths of elements with distance from the gold-bearing quartz veins. The best fitting model of dispersion pattern in altered wallrock around the gold-bearing quartz veins is an exponential function for Au, As, Sb, $Na_2O$ and Sr, and a quadratic function for CaO, $K_2O$, MnO, Ba, Rb and Cs. The primary dispersion widths are 15~343 cm in the hanging wall, and 33~173 cm in the footwall. The width of primary dispersion in the hanging wall is twice as thick as that in the footwall mainly due to the thermal effect and volatile components. The primary dispersion width is increased as the increase of gold-bearing quartz vein width and contents of As and Sb in gold-bearing quartz veins, but is not related to Au content in gold-bearing quartz veins.

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Characterization of Atmospheric Dispersion Pattern from Large Sources in Chungnam, Korea (충남지역 대형사업장의 대기오염물질 확산 특성 파악)

  • Choi, Woo Yeong;Park, Min Ha;Jung, Chang Hoon;Kim, Yong Pyo;Lee, Ji Yi
    • Particle and aerosol research
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    • v.17 no.3
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    • pp.55-69
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    • 2021
  • Chungnam region accounts for the largest SOX (22.8%) emission with the second-largest NOX (10.8%) emission in Korea due to the integration of many large industrial sources including a steel mill, coal-fired power plants, and petrochemical complex. Air pollutants emitted by large industrial sources can cause harmful problems to humans and the environment. Thus, it is necessary to understand dispersion patterns of air pollutants from large industrial sources in Chungnam to characterize atmospheric contamination in Chungnam and the surrounding area. In this study, seasonal atmospheric dispersion characteristics for SOX, NOX, and PM2.5 from ten major point sources in Chungnam were evaluated using HYSPLIT 4 model, and their contributions to SO2, NO2 concentrations in the regions near the source areas were estimated. The predictions of the HYSPLIT 4 model show a seasonal different dispersion pattern, in which air pollutants were dispersed toward the southeast in winter while, northeast in summer. In summer, due to weaker wind speed, air pollutants concentrations were higher than in winter, and they were dispersed to the metropolitan area. The local emissions of air pollutants in Taean area had a greater influence on the ambient SO2 and NO2 concentrations at Taean, whereas SOX and NOX emissions from large sources located at Seosan showed relatevely little effect on the ambient ambient SO2 and NO2 concentrations at Seosan.

The Application of Lagrangian Particle-Tracking Method to Modelling of Oil-Spill Dispersion (라그랑지안 입자추적법에 의한 유출유 확산모델링)

  • 정연철
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.3 no.1
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    • pp.73-83
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    • 1997
  • To predict the oil-spill dispersion in marine waters, the oil-spill dispersion model based on Lagrangian particle-tracking method was developed and applied to Kwangyang and Jinju Bay. The tidal current movements to be required as input data of the oil-spill dispersion model were obtained by a two-dimensional numerical tidal model. Evaluation of tidal current movements using mean tide was successful. Modelling results were compared with the field data obtained at spill site. There were some descrepancies between modeling results and field data. However, the general pattern of modelling results was similar to that of field data. Provided the real-time tidal currents and more accurate wind data are supported, more favorable results can be obtained.

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Rexonstruction of Pd Particles Supported on Silica in the Pressure of CO as Studied by Carbon-13 NMR

  • 한옥희;Gary L. Haller;Kurt W. Zilm
    • Bulletin of the Korean Chemical Society
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    • v.19 no.9
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    • pp.942-947
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    • 1998
  • The >$^13C$ NMR spectrum of >$^13CO$ adsorbed on Pd particles varies dramatically depending on dispersion. The spectrum of highly dispersed Pd particles supported on silica is a powder pattern ∼800 ppm wide with a first moment of 410 ppm. A low dispersion sample has a motionally narrowed line centered at 750±30 ppm and only ∼85 ppm full width at half height (FWHH). Over several years, high dispersion samples show an increase in the intensity near 750 ppm. These observations are interpreted as an increase of mobile bridging CO on high dispersion Pd surfaces of particles which resulted from smoothing of the metal particle surfaces in the presence of CO.