• 제목/요약/키워드: Ambient area

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자가조직도와 분산분석을 활용한 결빙 형상과 외기 조건의 관계 분석 (Analysis of Relations between Ice Accretion Shapes and Ambient Conditions by Employing Self-Organization Maps and Analysis of Variance)

  • 손찬규;오세종;이관중
    • 한국항공우주학회지
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    • 제39권8호
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    • pp.689-701
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    • 2011
  • 본 연구에서는 착빙 환경 요소와 결빙 형상 파라미터의 관계를 자가조직도와 분산분석을 활용하여 분석하였다. 결빙 형상에 영향을 미치는 외기 조건으로 자유류 속도, 대기온도, 대기중 물방울 함유량(LWC), 액적의 평균 직경(MVD)을 선정하였다. 그리고 결빙 형상의 특징이 되는 파라미터로 최대 두께, 결빙한계(Icing limit), 결빙 진행 방향, 결빙면적을 선정하였다. 자가 조직도의 결과는 결빙형상 파라미터에 관계가 있는 외기 조건에 대한 정성적인 관계를 제시하였고 분산분석의 결과는 형상 파라미터에 대한 외기 조건의 영향력의 상대적인 크기와 순위를 정량적으로 제시하였다.

교통량 과밀 도로주변의 토양과 가로수, 대기중 Pb, Cu, Zn 중금속 농도와 그 상관성에 관한 연구 (Pb, Cu, Zn Contaminants and Their Correlation of Soil, Leave and Bark of Ginkgo. B and Ambient Air Adjacent to a Heavy Traffic Road Side)

  • 박기학
    • 한국환경보건학회지
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    • 제18권2호
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    • pp.19-25
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    • 1992
  • The study was carried out to investigate the correlation between the heavy metals emitted by the motor vehicles with the heavy traffic road side environment (soil, leave, bark, ambient air). The Pb, Cu, Zn contents in road side soil sand leaves, barks from Ginkgo, biloba and ambient air adjacent to the heavy traffic road side from June to August, 1992 Suwon city were analyzed by Atomic absorption spectrometry and Inductively coupled plasma emission spectrophotometry. The results were as follows: 1) The high levels of heavy metals concentration were Pb, at city-terminal in soil (186 $\mu$g/g), Cu, at city-terminal in soil (221 $\mu$g/g), Zn, at city-terminal in ambient air (252 $\mu$g/m$^{3}$). 2) The low leves of heavy metals concentration were Pb, at North-gate in ambient air (1.65$\mu$g/m$^{3}$), Cu, at North-gate in ambient air (4 $\mu$g/m$^{3}$), Zn, at North-gate in ambient air (15.31$\mu$g/m$^{3}$). 3) The regional distribution of Pb, Cu, Zn in road side soils, leaves and barks from Ginkgo, biloba, ambient air show high levels in turn, city4erminal, Guan Sean Dong, South gate, North gate. 4) The concentration of heavy metals (Pb, Cu, Zn) in soils, leaves, barks, ambient air was highly correlated with the traffic volume of the sampling sites (r=0.64~0.96). To conclude that the high levels of Pb, Cu, Zn contaminations were positively related to motor vehicles-borne pollutants and road side soils, trees, ambient air adjacent to a high density building area with low road coverage and heavy traffic volume were reflected strongly by the hazardous pollutants emitted by motor vehicles.

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포항 지역 대기에서 측정된 에어로졸 입자분포 특성 연구 (A Characteristic Study of the Aerosol Size Distribution in Pohang Province)

  • 서문혁;장혁상
    • 한국입자에어로졸학회지
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    • 제8권4호
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    • pp.151-160
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    • 2012
  • Health effects caused by the ultrafine particles in ambient air are great concern to the public health, and the strict measuring and monitoring of the ambient aerosol are required. In this work, the characteristics of the aerosol size distribution in Pohang province are studied. Optical particle counters (Grimm APS 1108 and 1109) were used to measure the aerosol size distribution in the area. Locations near the national monitoring site located in the industrial and the residence area were selected for the measuring sites of this study, and the locations in border area between the industry and the residence were selected for the reference of the comparison. In the industry site, it is found that the concentration of aerosol particles near the size of 5 ${\mu}m$ appear characteristically and the fluctuations in concentration with respect to time are minimal. The mass concentration of the aerosol above 10 ${\mu}m$ in diameter in the industry area was found to fluctuate significantly. The mass portion of $PM_{10}$ and PM2.5 to TSP in the residence area were 83% and 51% respectively. In the industrial regional, it was found that the mass portion of PM10 and $PM_{2.5}$ to TSP were 76% and 35% respectively. In the boundary area the mass portion of $PM_{10}$ and $PM_{2.5}$ to TSP were 78% and 54% respectively.

Comparison of Major Monoterpene Concentrations in the Ambient Air of South Korea Forests

  • Oh, Gil-Young;Park, Gui-Hwan;Kim, Ik-San;Bae, Ju-Soon;Park, Hye-Young;Seo, Yun-Gyu;Yang, Soo-In;Lee, Joong-Ki;Jeong, Sun-Ho;Lee, Wan-Jin
    • 한국산림과학회지
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    • 제99권5호
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    • pp.698-705
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    • 2010
  • The concentration of monoterpenes (12 species) was measured from spring to fall in 2008 in ambient air at six different forests located in the southern parts of Korea. Sampling - using a Solid Adsorption Tube - was conducted at 2-hour-interval a day (24 hours) of each season. The highest annual average concentration of total monoterpene was 0.715 ppbv, which occurred at Mt. Baega. ${\alpha}$-Pinene, sabinene and ${\beta}$-pinene were the most abundant compounds throughout the sampling periods and areas. The concentrations of monoterpene were higher in spring than in any other seasons. The compositions and concentrations of monoterpene displayed a distinct pattern by area. Most of monoterpenes had diurnal variations with higher concentrations during the daytime, and lower during the nighttime. This may be due to the fact that the amount of monoterpenes emitted increases at elevated ambient temperatures and increased sunlight intensity. The results of this study showed that each area had distinct monoterpene compositions, which depended on the tree species, topography and local climate at each area.

Directional frequency analysis and recording 소노부이의 표적 탐지 성능 향상을 위한 위너필터링 기반 주변 소음 제거 기법 (Wiener filtering-based ambient noise reduction technique for improved acoustic target detection of directional frequency analysis and recording sonobuoy)

  • 홍정표;배인영;석종원
    • 한국음향학회지
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    • 제41권2호
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    • pp.192-198
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    • 2022
  • DIrectional Frequency Analysis and Recording(DIFAR) 소노부이는 대잠전에 효과적인 무기체계로 하나의 무지향성 센서와 두 개의 지향성 센서로 구성된 3채널 빔형성을 통해 표적의 방향을 탐지한다. 하지만, 주변 소음의 영향으로 DIFAR소노부이의 특정방위(0°, 90°, 180°, 270°) 표적 탐지 성능이 저하되는 단점이 있다. 따라서, 본 논문에서는 주변 소음을 추정하고 제거를 통해 DIFAR 소노부이의 표적 탐지 성능을 향상시키는 방법을 제안하였다. 주변 소음 추정을 위해 소나신호처리에서 널리 쓰이는 Order Truncate Average(OTA)기법을, 추정된 소음을 제거하기 위해 음성신호처리에서 널리 쓰이는 위너필터링 기법을 사용하였다. 제안한 방법을 평가하기 위해 표적 방위추정 결과의 평균 제곱 오차를 비교한 결과 신호대잡음비 0 dB이하에서 제안한 방법이 효과적임을 확인할 수 있었다.

수도권 대기 미세먼지 1999-2008년 추이 분석 (Analysis of the trend of atmospheric PM10 concentration over the Seoul Metropolitan Area between 1999 and 2008)

  • 김용표
    • 환경영향평가
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    • 제19권1호
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    • pp.59-74
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    • 2010
  • The trend of the PM10 concentrations in the Seoul Metropolitan Area (SMA) is reviewed and relative contributions of major contributors (paved road emissions and long-range transport from outside the SMA) are discussed. It was shown that the PM10 concentrations in the SMA have generally decreased except Incheon between 1999 and 2005. Further, it was identified that the difference of the PM10 mass concentration between the roadside stations and urban ambient stations has decreased between 2004 and 2008. Based on the emission estimates, it was suggested that the reduction of resuspension of aerosols on the road is the major reason for that. Based on the modeling results, it was identified that outside effects be about 30% of the ambient PM10 concentration in the SMA. Further research and policy issues to identify major sources of PM10 in the SMA are discussed.

Seismic study of buildings with viscoelastic dampers

  • Pong, W.S.;Tsai, C.S.
    • Structural Engineering and Mechanics
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    • 제3권6호
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    • pp.569-581
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    • 1995
  • In this paper, the seismic behavior of a 10-story building equipped with viscoelastic dampers is analyzed. The effects of ambient temperature, the thickness, the total area, and the position of the viscoelastic dampers are studied. Results indicate that the energy-absorbing capacity of viscoelastic damper decreases with increasing the ambient temperature. The thickness and the total area of viscoelastic dampers also affect the seismic mitigation capacity. The thickness cannot be too small, which is not effective in vibration reduction, nor can it be too large, which not only increases the cost but also reduces the seismic resistance. The total area of viscoelastic dampers should be determined properly for optimum damper performance at the most economical design. The mounting position of viscoelastic dampers also influences the structure's seismic performance. Numerical results show that, if properly equipped, the VE dampers can reduce the structural response both floor displacement and story shear force and increase the overall level of damping in structures during earthquakes.

공비혼합물로 제조된 다공성 센서재료용 실리카 에어로젤 (Silica aerogels for potential sensor material prepared by azeotropic mixture)

  • 안나 쉴랴흐티나;오영제
    • 센서학회지
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    • 제16권6호
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    • pp.395-400
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    • 2007
  • Ambient drying sol-gel processing was used for monolithic silica ambigels in the temperature range of $130-250^{\circ}C$. A new method of mesopore ambigels, which mean the aerogels prepared by ambient pressure drying process synthesis, is suggested at first. This method includes two important approaches. The first point is that $SiO_{2}$ surface modification of wet gel was performed by trimethylchlorosilane in n-butanol solution. This procedure is provided the silica gel mesopore structure formation. The second point is a creation of the ternary azeotropic mixture water/n-butanol/octane as porous liquid, which is effectively provided removing of water such a low temperature by 2 step drying condition under ambient pressure. The silica aerogels, which were prepared by ambient pressure drying from azeotropic mixture of water/n-butanol/octane, are transparent, crack-free and mesoporous (pore size ${\sim}$ 5.6 nm) with surface area of ${\sim}$ $923{\;}m^2/g$, bulk density of $0.4{\;}g/cm^3$ and porosity of 85 %.

시화공단 지역의 주요 휘발성물질 농도 분포 특성 (Patterns of the main VOCs concentration in ambient air around Shiwha Area)

  • 변상훈;이정근;김정근
    • 대한환경공학회지
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    • 제32권1호
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    • pp.61-68
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    • 2010
  • 본 연구에서는 시화지구의 공단과 주거 지역에서의 휘발성 유기화합물 농도를 측정하고 그 특성을 비교 분석하였다. 공단지역과 주거지역 21개소에 passive sampler를 1개월간 설치하여 총 6회에 걸쳐 벤젠, 트리클로로에틸렌, 톨루엔, 에틸벤젠, 자일렌과 스티렌을 채취하였다. 그 결과 VOCs 물질 중 톨루엔이 공단지역과 주거지역에서 가장 높은 농도로 검출되었다. 공단지역의 평균 TVOC농도는 주거지역의 1.86배에 해당했으며, 여름철에 비해 겨울철에는 그 농도가 크게 감소하였다. 또한, 평균 BTEX 농도는 공단지역의 화합물의 농도가 주거지역보다 1.94~5.39배 더 높은 것을 보여준다. 에틸벤젠과 자일렌은 여름철에 비교해 겨울철에 농도가 감소하였으나, 벤젠은 더 높은 농도로 측정되었다. VOCs 간의 상관계수는 공단지역에서의 물질간의 상관성이 주거지역보다 좀 더 큰 것으로 나타내었다. 공단지역에서는 대체로 양의 상관성을 보이는 물질들이 주거지역에서는 에틸벤젠과 톨루엔의 경우를 비롯해 음의 상관성을 보였다. 전반적으로, VOCs 농도는 공단지역에서 더 높았으며, 주거지역의 VOCs 분포에 잠재적으로 영향을 미치는 것으로 파악할 수 있다.