• Title/Summary/Keyword: Sky

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Optical Properties of Aerosol at Gongju Estimated by Ground-based Measurements Using Sky-radiometer (스카이라디오미터(Sky-radiometer)로 관측된 공주지역 에어로솔의 광학적 특성)

  • Kwak, Chong-Heum;Suh, Myoung-Seok;Kim, Maeng-Ki;Kwak, Seo-Youn;Lee, Tae-Hee
    • Journal of the Korean earth science society
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    • v.26 no.8
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    • pp.790-799
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    • 2005
  • We investigate the optical properties of aerosols over Gongju by an indirect method using the pound measurement, Sky-radiometer. The analysis period is from January to December, 2004. Skyrad. pack.3 is used to estimate the optical properties, such as the aerosol optical thickness (AOT), single scattering albedo (SSA), ${\AA}ngstron$ exponent $({\alpha})$ and size distribution, of aerosols from the ground measured radiance data. And qualify control is applied to minimize the cloud-contaminated data and improve the quality of analysis results. The 12-month average of AOT, ${\alpha}$, and SSA are 0.46, 1.14, and 0.91, respectively. The average volume spectra of aerosols shows a bi-modal distribution, the first peak at fine mode and the second peak at coarse mode. AOT and coarse particles clearly increases while SSA decreases during the Asian dust events. The optical properties of aerosols at Gongju vary with?seasons, but those are not influenced by the wind direction.

The differences in Constellation drawings among different countries

  • Karimova, Ulkar;Yi, Yu;Oh, Suyeon
    • The Bulletin of The Korean Astronomical Society
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    • v.37 no.2
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    • pp.95-95
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    • 2012
  • Constellations are formed of bright stars which appear close to each other on the sky, but are really far apart in space. The shapes you see all depend on your point of view. Back before people had televisions and electricity to light their homes at night, they spent a lot more time looking at the stars. People all over the world used their imaginations to draw pictures in the sky, as if it were a giant connect-the-dot game. The patterns they imagined are called constellations. People usually saw patterns that reflected their different cultures. Native Americans in North America imagined many animals and shapes from the natural world. The ancient Greeks found images of gods and goddesses in the stars. Sometimes people from very different parts of the world even imagined the same animal or shape in the same stars. Most of the constellations we recognize today were made up by the ancient Greeks around 6,000 years ago. Different constellations are visible at different times of year, so the first appearance of these patterns told farmers of the changing seasons and reminded them to plant or harvest their crops. The constellations also help us to find our way around the night sky and to remember which stars are which. The star names we use today are mostly from Greek and Arabic, but many are changed a bit from the original, as often happens when words are passed from one language to another. It can be difficult to picture just what those folks long ago were seeing in the stars, so don't be discouraged if you have trouble seeing their patterns. You can even make up your own! In ancient world all the countries or regions had their own way to name things up in the sky, make up stories and draw different shapes for constellations. Today there are 88 official constellations, but you may find that different books show their stars connected in slightly different ways. The official constellations are specific regions of the sky, so the exact patterns are not all that important. However in various cultures there are some famous star patterns that use stars from only apart of a constellation, or even connect stars from different constellations. These patterns of stars that are not official constellations are called asterisms. The Big Dipper is a very famous asterism, found in the constellation Ursa Major, or Great Bear.

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An Experimental Study on the Reduction Effects of Shading Devices on Sky Radiant Cooling in Winter (차양장치의 겨울철 천공복사 냉각 저감 효과에 관한 실험적 연구)

  • Kim, Jin-Hee;Kim, Young-Tag;Lee, Soo-Yeol;Choi, Won-Ki
    • Land and Housing Review
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    • v.12 no.1
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    • pp.129-137
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    • 2021
  • External shading devices are well known solar control devices that can help reduce the cooling load of commercial buildings. For this study, experiments were conducted to examine the feasibility of shading devices in reducing both the cooling and heating loads. The influence of sky radiant cooling during winter was verified for the external shading device, internal roller blind, and window. Results can be summarized as follows. The temperature difference between the inner and outer surfaces of the window with the external shading device was 11.8℃ compared to 14.6℃ for one without the external shading device. This 2.8℃ difference was due to heat exchange by sky radiation when the surface temperature of the shading device was lower than the ambient outdoor air temperature. The roller blind resulted in a lower temperature of 0.8℃ compared to the average temperature of the window's air cavity. This was due to heat exchange by sky radiation of the roller blind surfaces. Without shading devices, the outside surface temperature of the window is about 3℃ higher. The study also found that when external shading devices were installed on both the southwest and southeast sides, the outside surface temperature of the windows were lower on the southwest side than the southeast side.

An Analysis of Observational Environments for Solar Radiation Stations of Korea Meteorological Administration using the Digital Elevation Model and Solar Radiation Model (수치표고모델과 태양복사모델을 이용한 기상청 일사 관측소 관측환경 분석)

  • Jee, Joon-Bum;Zo, Il-Sung;Kim, Bu-Yo;Lee, Kyu-Tae
    • Journal of the Korean earth science society
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    • v.40 no.2
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    • pp.119-134
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    • 2019
  • In order to analyze the observational environment of solar radiation stations operated by the Korea Meteorological Administration (KMA), we used the digital elevation model (DEM) and the solar radiation model to calculate a topographical shading, sky view factor (SVF) and solar radiation by surrounding terrain. The sky line and SVF were calculated using high resolution DEM around 25 km of the solar stations. We analyzed the topographic effect by analyzing overlapped solar map with sky line. Particularly, Incheon station has low SVF whereas Cheongsong and Chupungryong station have high SVF. In order to validation the contribution of topographic effect, the solar radiation calculated using GWNU solar radiation model according to the sky line and SVF under the same meteorological conditions. As a result, direct, diffuse and global solar radiation were decreased by 12.0, 5.6, and 4.7% compared to plane surface on Cheongsong station. The 6 stations were decreased amount of mean daily solar radiation to the annual solar radiation. Among 42 stations, eight stations were analyzed as the urgent transfer stations or moving equipment quickly and more than half of stations (24) were required to review the observational environment. Since the DEM data do not include artifacts and vegetation around the station, the stations need a detail survey of observational environment.

The Comparison of the Solar Radiation and the Mean Radiant Temperature (MRT) under the Shade of Landscaping Trees in Summertime (하절기 조경용 녹음수 수관 하부의 일사와 평균복사온도 비교)

  • Lee, Chun-Seok;Ryu, Nam-Hyung
    • Journal of the Korean Institute of Landscape Architecture
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    • v.42 no.5
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    • pp.22-30
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    • 2014
  • The purpose of this study was to compare the Solar Radiation(SR) and the Mean Radiant Temperature(MRT) under the shades of the three landscaping trees in clear summer daytimes. The trees were Lagerstroemia indica, Quercus palustris and Ulmus parvifolia. The solar radiation, the globe temperature and the air temperature were recorded every minute from the $1^{st}$ of April to the $30^{th}$ of September 2013 at a height of 1.1m above on the four monitoring stations, with four same measuring system consisting of a solar radiation sensor, two resistance temperature detectors(Pt-100), a black brass globe (${\phi}50mm$) and data acquisition systems. At the same time, the sky view photos were taken automatically hourly by three scouting cameras(lens angle: $60^{\circ}$) fixed at each monitoring station. Based on the 258 daily sky view photos and 6,640 records of middays(10 A.M.~2 P.M.) from the $1^{st}$ of June to the $30^{th}$ of August, the time serial differences of SR and MRT under the trees were analysed and compared with those of open sky, The major findings were as follows; 1. The average ratio of sky views screened by the canopies of Quercus palustris, Lagerstroemia indica and Ulmus parvifolia were 99%, 98% and 97%, and the SR were $106W/m^2$, $163W/m^2$ and $202W/m^2$ respectively, while the SR of open sky was $823W/m^2$. Which shows the canopies blocked at least 70% of natural SR. 2. The average MRT under the canopies of Quercus palustris, Lagerstroemia indica and Ulmus parvifolia were $30.34^{\circ}C$, $33.34^{\circ}C$ and $34.77^{\circ}C$ respectively, while that of open sky was $46.0^{\circ}C$. Therefore, it can be said that the tree canopies can reduce the MRT around $10{\sim}16^{\circ}C$. 3. The regression test showed significant linear relationship between the SR and MRT. In summary, the performances of the landscaping shade trees were very good at screening the SR and reducing the MRT at the outdoor of summer middays. Therefore, it can be apparently said that the more shade trees or forest at the outdoor, the more effective in conditioning the outdoor space reducing the MRT and the useless SR for human activities in summertime.