• 제목/요약/키워드: Large-area

검색결과 8,189건 처리시간 0.04초

Fermi Large Area Telescope Observations of the Dark Accelerator HESS J1745-303

  • Yeung, Paul
    • Journal of Astronomy and Space Sciences
    • /
    • 제33권4호
    • /
    • pp.319-321
    • /
    • 2016
  • Reviewing the two MeV-GeV investigations in the field of the HESS J1745-303 performed using Fermi Large Area Telescope data, we confirmed that the emission peak comfortably coincides with 'Region A' in the TeV regime, which is the brightest part of this feature. The MeV-TeV spectrum can be precisely described by a single power-law. Also, recent investigation has shown that the MeV-GeV feature is elongated from 'Region A' toward the north-west, which is similar to the case of largescale atomic/molecular gas distribution.

표면에너지와 거칠기가 응착력에 미치는 영향 (The Effects of Surface Energy and Roughness on Adhesion Force)

  • 나종주;권식철;정용수
    • 대한기계학회논문집A
    • /
    • 제30권11호
    • /
    • pp.1335-1347
    • /
    • 2006
  • Surface energies calculated from measured contact angles between several solutions and test samples, such as Si wafer, $Al_2O_3$, $SiO_2$, PTFE(Polytertrafluoroethylene), and DLC(Diamond Like Carbon) films, based on geometric mean method and Lewis acid base method. In order to relate roughness to adhesion force, surface roughness of test samples were scanned large area and small by AFM(Atomic Force Microscopy). Roughness was representative of test samples in large scan area and comparable with AFM tip radius in small scan area. Adhesion forces between AFM tip and test samples were matched well with order of roughness rather then surface energy. When AFM tips having different radius were used to measure adhesion force on DLCI film, sharper AFM tip was, smaller adhesion force was measured. Therefore contact area was more important factor to determine adhesion force.

가공 송전 철탑기초 설계 및 시공 방법 연구 - 심형기초를 중심으로 - (A Study on the Transmission Tower Foundation Design and Construction Method - A Focus of Cylindrical Foundation -)

  • 장석한;김희광;이강현;한경수;함방욱;정기선
    • 전기학회논문지
    • /
    • 제56권6호
    • /
    • pp.1031-1034
    • /
    • 2007
  • Electric transmission lines pass through a variety of area. Foundation supporting the conductors and tower are selected properly in accordance with external load, for example dead load, wind load, snow load, construction load etc, and topography and geology condition. Typical types of foundation are as follows: pad foundation for small load and hard soil or rock in mountainous area, pile foundation for medium or large load and soft soil in plain field area. This paper introduced cylindrical foundation design & construction for large load and mountainous area. This foundation failure mode against pulling-out show splitting failure by tensile force toward circumferential direction.

난지도지역의 수은배출특성 연구: 배출공 내부의 농도와 배출공을 통한 수은플럭스의 관측 (Studies of Hg Concentrations and Fluxes in the Ventpipes Determined from a Large Landfill Site)

  • 김민영;김기현;조석주
    • 한국대기환경학회지
    • /
    • 제17권4호
    • /
    • pp.299-312
    • /
    • 2001
  • The analysis of vent -emitted Hg concentrations and relevant environmental parameters was made from the inlet of 42 ventpipes in Nan-Ji-Do area of Seoul during September/october of 2000. Using these data, the fluxes of Hg from the ventpipes were also derived. The mean concentration of Hg, computed using the data sets collected from 42 ventpipes, was 420$\pm$619ng m$^{-3}$ with the range of 3.45~2,952ng m$^{-3}$ . Because of large differences in concentration levels between two sectors 1 and 2 and between plain and slope areas. evaluation of the data was made by dividing them into four different categories such as plain areas of sectors 1 and 2 (and/or slope areas of sectors 1 and 2). When this classification was applied, the computed fluxes were highly different among each group with the generally enhanced fluxes in plain area relative to slope area. The computed fluxes were then used to make comparative analysis of different source processes in the study area.

  • PDF

녹지의 대기정화효과 분석을 위한 해석적 대기확산모델의 유도 (Analytic Model for Concentration Deficit Profile Caused by a Large Vegetated Area)

  • 김석철
    • 한국대기환경학회지
    • /
    • 제16권5호
    • /
    • pp.539-544
    • /
    • 2000
  • A simple analytic model is proposed here to analyze the concentration deficit field caused by a large area of vegetated area. With non-dimensional deposition velocity chosen as small parameter, the regular perturbation method is exploited to derive the mass balance equation and the dynamic equations for the concentration deficit field, Analytic solutions to those equations are obtained in a closed form for several cases of interest, assuming that the concentration field is stationary and the plume can be nicely approximated as Gaussian for a point source. The results suggest that quite a negligible fraction (less than 1%) of the gaseous air pollutants emitted into the air is removed by the vegetated area of which width is 4 km in wind-wise direction, the typical dimension of the Restricted Development Zones around the metropolitan regions in South Korea.

  • PDF

대형직접전단시험에 의한 RAP 복합지반의 전단강도 특성 연구 (A Study on the Shear Strength Characteristics of Composited Ground applying RAP Method by Large Direct Shear Test)

  • 천병식;서덕동;김종산
    • 한국지반공학회:학술대회논문집
    • /
    • 한국지반공학회 2004년도 춘계학술발표회
    • /
    • pp.82-89
    • /
    • 2004
  • To secure stability and availability of Rammed Aggregate Pier method as the foundation of a structure, the shear strength characteristics according to the area replacement ratio of RAP and the relative density of in-situ ground was studied through soil laboratory tests and large direct shear tests in a model ground. As a result, the internal friction angle tends to increase in proportion to in-situ relative density(Very Loose, Loose, Medium) in composite ground formed by the same area replacement ratio of RAP and also increase in proportion to increasing the area replacement ratio(30, 40, 50%) of RAP in the same ground condition. Furthermore, the comparative analysis between the experimental value and theoretical value of the shear strength is carried out.

  • PDF

멀티비트 리코딩 병렬 승산기의 최적설계를 위한 면적-시간 복잡도 분석 (Area-time complexity analysis for optimal design of multibit recoding parallel multiplier)

  • 김득경;신경욱;이용석;이문기
    • 전자공학회논문지A
    • /
    • 제32A권5호
    • /
    • pp.71-80
    • /
    • 1995
  • The usual approach for desinging a fast multiplier involves finding a way to quickly add up all the partial products, based on parital product recoding scheme and carry-save addition. This paper describes theoretical medels for area and time complexities of Multibit Reconding Paralle Multiplier (MRPM), which is a generalization of the modified Booth recoding scheme. Based on the proposed models, time performance, hardware requirements and area-time efficiency are analyzed in order to determine optimal recoding size for very large scale integration (VLSI) realization of the MRPM. Some simulation results show that the MRPM with large multiplier and multiplicand size has optimal area-time efficiency at the recoding size of 4-bit.

  • PDF