• 천문학회보
• /
• 제26권2호
• /
• pp.34-34
• /
• 2001

• 천문학회보
• /
• 제28권2호
• /
• pp.73-73
• /
• 2003

• 천문학회지
• /
• 제35권2호
• /
• pp.97-103
• /
• 2002

We have mapped 1 $deg^2$ region toward a high latitude cloud MBM 40 in the J = 1 - 0 transition of $^{12}CO$ and $^{13}CO$, using the 3 mm SIS receiver on the 14 m telescope at Taeduk Radio Astronomy Observatory. We used a high resolution autocorrelator to resolve extremely narrow CO linewidths of the molecular gas. Though the linewidth of the molecular gas is very narrow (FWHP < 1 km $s^{-1}$ ), it is found that there is an evident velocity difference between the middle upper part and the lower part of the cloud. Their spectra for both of $^{12}CO$ and $^{13}CO$ show blue wings, and the position-velocity map shows clear velocity difference of 0.4 km $s^{-1}$ between two parts. The mean velocity of the cloud is 3.1 km $s^{-1}$. It is also found that the linewidths at the blueshifted region are broader than those of the rest of the cloud. We confirmed that the visual extinction is less than 3 magnitude, and the molecular gas is translucent. We discussed three mass estimates, and took a mass of 17 solar masses from CO integrated intensity using a conversion factor $2.3 {\times} 10^{20} cm^{-2} (K\;km s^{-1})^{-1}$. Spatial coincidence and close morphological similarity is found between the CO emission and dust far-infrared (FIR) emission. The ratio between the 100 f.Lm intensity and CO integrated intensity of MBM 40 is 0.7 (MJy/sr)/(K km $s^{-1}$), which is larger than those of dark clouds, but much smaller than those of GMCs. The low ratio found for MBM 40 probably results from the absence of internal heating sources, or significant nearby external heating sources.

• Journal of Platform Technology
• /
• 제8권4호
• /
• pp.59-69
• /
• 2020

최근 초미세먼지 및 미세먼지에 대한 심각성은 국가적 차원의 재난으로 대두되고 있으나 지방 중소도시는 면적에 비해 미세먼지 측정소가 부족하여 미세먼지관리가 어려운 측면이 있다. 미세먼지 데이터의 수집과 처리를 위한 컴퓨팅자원은 규모가 크지않지만 데이터를 공유를 위하여 클라우드와 민간 및 공공데이터를 활용하는 것이 필요하다. 본 논문에서는 미세먼지 및 초미세먼지 그리고 온·습도를 측정하여 이를 처리하여 미세먼지 실시간 관제와 대국민서비스할 수 있는 소형 엣지컴퓨팅 시스템을 제안하였다. 미세먼지 데이터의 수집과 공공 및 민간데이터를 활용하여 미세먼지 등급을 서비스하는 것은 데이터양이 크지 않고 처리부하가 크지 않기 때문에 라즈베리파이를 이용한 엣지컴퓨팅으로 처리하는 것이 효율적이다. 실험을 위하여 3가지 센서와 라즈베리파이 그리고 Thinkspeak를 이용하여 실험시스템을 구성하였으며 경북북부권지역에 대한 미세먼지 측정을 실험하였다. 실험결과 민간의 GIS데이터 기반에 시간에 따른 측정된 미세먼지 측정결과가 정확하게 확인되었다.

• 한국환경과학회:학술대회논문집
• /
• 한국환경과학회 2003년도 International Symposium on Clean Environment
• /
• pp.51-54
• /
• 2003

We analyzed radiative properties of aerosols, $CO^{2}$ and clouds using Optical Properties of Aerosols and Clouds(OPAC) and the Column Radiation Model (CRM). From OPAC, if the soot component is disregarded, dust-like components depict the highest extinction values in the solar spectral range and the lowest. single scattering albedoes, which are attributable to the presence of large particles. In the dust aerosol, the high absorptivity in the infrared may induce a warming of the lower atmospheric layer in the nighttime. The radiative properties of aerosols, clouds and double $CO^{2}$ using the CRM model at Seoul (37N, 127.4 E) on 3 April 2003 were calculated. The solar zenith angle is 65˚ and the surface albedo is 0.1836 during the clear day. The aerosol optical depth change 0.14 to 1.7, which is derived during Asian dust days in Korea. At this time, abedo by aerosols is considered as 0.3. In cloudy condition, the short wave cloud forcing on both the TOA and the surface is -193.89 $Wm^{-2}$ and -195.03 $Wm^{-2}$, respectively, and the long wave cloud forcing is 19.58 $Wm^{-2}$ and 62.08 $Wm^{-2}$, respectively. As a result, the net radiative cloud forcing is -174.31 $Wm^{-2}$ and -132.95 $Wm^{-2}$, respectively. We calculate also radiative heating rates by double $CO^{2}$ during the clear day. The $CO^{2}$ volumn mixing ratio is 3.55E-4.

• 천문학논총
• /
• 제23권2호
• /
• pp.31-35
• /
• 2008

We present analytical approximations for calculating the scattering and escape of non-ionizing photons from a plane-parallel medium with uniformly illuminated by external sources. We compare the results with the case of a spherical dust cloud. It is found that more scattering and absorption occur in the plane-parallel geometry than in the spherical geometry when the optical depth perpendicular to the plane and the radial optical depth of the sphere are the same. The results can provide an approximate way to estimate radiative transfer in a variety interstellar conditions and can be applied to the dust-scattered diffuse Galactic light.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
• /
• pp.385-387
• /
• 2005

Polarimetric measurements of the sky radiation by the PSR-I000, which is the multi-spectral polarimeter developed by the Opt Research Corporation and has the same wavelength regions (443nm, 490nm, 565nm, 670nm, 765nm and 865nm) as the ADEOSII/POLDER sensor, have been carried out at the ground station in Kanazawa city, Japan from March to May. First of all, the wavelength dependency of degrees of polarization is examined and it is shown that degrees of polarization measured under the hazy dust cloud are lower than those measured in the clear sky and decrease as the wavelength increases. Next, a new method for estimating optical properties, such as the optical thickness, the number size distribution and the refractive index, of the Asian dust and the ground reflectance from degrees of polarization measured by PSR-I000 is described. Finally, this method is applied to polarization data acquired on April 15,2002. As a result, it is shown that our estimation algorithm provides a good result.

• 대한원격탐사학회지
• /
• 제32권2호
• /
• pp.119-131
• /
• 2016

한반도 에어로졸 라이다 관측 네트워크(Korea Aerosol Lidar Observation Network; KALION)의 라이다 관측자료 처리 및 실시간 표출을 위한 표준 알고리즘을 개발하였다. KALION 표준 알고리즘은 라이다 관측으로부터 얻어진 후방산란강도와 편광소멸도 자료를 이용하여 (1) 에어로졸과 구름 구분, (2) 에어로졸 유형 구분, (3) 에어로졸 소산계수 그리고 (4) 에어로졸 질량농도를 산출하는 단계로 구성이 되어 있다. 에어로졸의 유형은 후방산란강도와 편광소멸도 자료에 근거하여, (대륙 기원) 청정기단 에어로졸(clean continental aerosol), 황사(dust aerosol) 그리고 오염 입자(polluted continental/urban pollution aerosol)로 구별된다. 에어로졸 소산계수에 필요한 라이다 상수는 약 9년간의 라이다와 스카이 라디오미터 자료로부터 도출된 63.31 sr을, 에어로졸 질량소산효율은 약 9년간의 라이다와 기상청 Particulate Matter($PM_{10}$) 질량농도 자료를 이용하여 도출된 $3.36m^2\;g^{-1}$ (황사는 $1.39m^2\;g^{-1}$)을 적용한다. 2015년 3월 28일부터 30일까지 라이다 관측 사례(서울 관악)에서 KALION 표준 알고리즘을 통해 산출된 에어로졸 유형 구분, 특히 황사 판별 결과는 기상청의 황사 보고와 잘 일치하였으며, 2006년 6월부터 약 9년 동안의 라이다 관측자료로부터 산출된 에어로졸 질량농도 역시 지상 $PM_{10}$ 농도와 약 $3{\mu}g\;m^{-3}$ 내에서 잘 일치하였다. 향후 에어로졸의 유형에 따른 서로 다른 라이다 상수 및 에어로졸 질량소산효율 적용 알고리즘, 빙정 구름(ice cloud)과 물방울 구름(water droplet cloud) 구분 알고리즘, 그리고 운저 고도와 혼합고 판별 알고리즘을 개발할 계획에 있다.

• 천문학회보
• /
• 제41권2호
• /
• pp.40.2-40.2
• /
• 2016

The attenuation of starlight by dust in galactic environments is investigated through models of radiative transfer in a spherical, clumpy interstellar medium (ISM). We show that the attenuation curves are primarily determined by the wavelength dependence of absorption rather than by the underlying extinction (absorption+scattering) curve; the observationally derived attenuation curves cannot constrain a unique extinction curve unless the absorption or scattering efficiency is specified. Attenuation curves consistent with the Calzetti curve are found by assuming the silicate-carbonaceous dust model for the Milky Way (MW), but with the $2175{\AA}$ bump suppressed or absent. The discrepancy between our results and previous work that claimed the Small Magellanic Cloud dust to be the origin of the Calzetti curve is ascribed to the difference in adopted albedos; we use the theoretically calculated albedos whereas the previous ones adopted empirically derived albedos from observations of reflection nebulae. It is found that the model attenuation curves calculated with the MW dust are well represented by a modified Calzetti curve with a varying slope and UV bump strength. The strong correlation between the slope and UV bump strength, as found in star-forming galaxies at 0.5 < z < 2.0, is well reproduced if the abundance of the UV bump carriers is assumed to be 30-40% of that of the MW-dust; radiative transfer effects lead to shallower attenuation curves with weaker UV bumps as the ISM is more clumpy and dustier. We also argue that some of local starburst galaxies have a UV bump in their attenuation curves, albeit very weak.

• 한국대기환경학회지
• /
• 제10권4호
• /
• pp.233-244
• /
• 1994

The phenomenon of yellow sand (dust clouds) occurred in Korea during the spring of 1993 and 1994 is studied in detail. In total 6 cases including 15 days of yellow sand were observed in 1993 and the annual number of these events was found to increased. Examinations in this study include meteorological charts satellite imagery, pilot reports (PIREP) of Korea Air Force, and air concentrations of total suspended particulates(TSP). We present on estimation of total atmospheric loadings based on the observation and theory. According to the PIREP, in general the dust clouds travelled in the lower troposphere up to the level 5km. The visibility within the clouds was in the range of 3-8km The area covered by yellow sand in an event exceeded 0.4 M $\textrm{km}^2$ . According to trajectory analyses, dust clouds invaded Korea in April and May 1993 were landed in the sink area after 2~4 days travelling for 2,000~3,000km from a source region. Estimates of total atmospheric loadings of a dust cloud for April 23~24 in 1993 were 1.5 M ton. In addition, 7 dust storms were also reported in synoptic observations in NW China and Mongolia during the spring in 1994. The yellow sand was not reported with meteorological observations in Korea, however pilots reported significant dust clouds over the Yellow Sea on 8 and 13 April and 20 May 1994.