• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.53-54
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• 2022

There is an increasing demand for prediction of asbestos concentration which has an fatal effect on human body. While demolishing asbestos, the dust scatters and makes workers be exposed to danger. Up to this date, however, factors that particularly influences have not considered in predicting asbestos concentration. Most of the studies could not quantify the distribution of asbestos. Also, they did not use nominal data on buildings as important factors. Therefore, this study aims to build an asbestos concentration prediction model by quantifying distribution of asbestos and using nominal data of buildings based on Artificial Neural Network (ANN). This model can give significant contribution of improving the safety of workers and be useful for finding effective ways to demolish asbestos in planning.

• 한국대기환경학회지
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• 제33권4호
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• pp.361-369
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• 2017

In this study, the characteristics of the dust emission according to the presence or absence of operation of the gas stove were analyzed by particle size analysis and density estimation while the mackerel was cooked while the fan was placed on the gas stove used in the home. The experiment was carried out using 20 mackerel of normal size at home. Commercially available canola oil was used as edible oil. In order to understand the characteristics such as particle size distribution of fine dust, light scattering measurement method which can be measured at intervals of several seconds was used. Particles generated by combustion of gas stove, particles formed by heating cooking oil, and particles generated by heating mackerel fish meat are judged to be nano size particles smaller than $1{\mu}m$. Therefore, it is necessary to use precise measurement method rather than the measurement method using the filter which is currently being measured in the measurement of the particles discharged from the fuel combustion or food cooking in the future. Analyzing the particle size and density of the dust emitted from the cooking stove is expected to contribute technically to the reduction of dust emissions from the cooking process of gas and fuel facilities at home and commercial facilities.

• 대한원격탐사학회지
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• 제36권2_1호
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• pp.93-101
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• 2020

본 연구는 국내 최초로 안면도, 고산, 광주, 서울에서 측정된 AERONET 선포토미터 자료를 편광소멸도(δ)와 단산란 알베도(SSA)를 이용하여 에어로졸의 유형을 PD, DDM, PDM, NA, WA, MA, SA의 7가지 유형으로 구분하고 계절별, 연도별 발생빈도와 유형별 AOD변화를 살펴보았다. 오염입자(NA, WA, MA, SA를 합한 비율)의 비율은 각각 58.9, 46.2, 59.5, 67.1%로 서울이 가장 높고 고산이 가장 낮았다. 연간 비율 변화는 NA는 증가하고 PD, DDM은 감소하는 경향을 보였다. 유형별 AOD는 NA가 모든 사이트에서 가장 높은 값을 보였다. 또한, NA의 비율과 AOD는 지속적으로 증가하는 추세를 보였다.

• 대한원격탐사학회지
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• 제29권4호
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• pp.407-413
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• 2013

본 연구에서는 에어로졸의 종류에 따른 광흡수 특성을 표시할 수 있는 새로운 에어로졸 파라미터인 Modified Aerosol Factor(MAF)를 산출하였다. MAF는 AERONET의 선포토미터로부터 산출되는 4 파장(440, 675, 870 그리고 1020 nm)의 단산란알베도로부터 도출되었다. 에어로졸 종류에 단산란알베도 값이 파장 증가에 따라 다른 형태를 보이는 점으로부터 4파장의 단산란알베도를 이용하여 선형회귀분석을 수행하고 분석값의 기울기 값을 산출하였다. 먼지입자는 기울기 값이 양의 값을 보이고, 순수한 먼지입자 일수록 높은 값을 보였다. 다른 종류의 에어로졸이 혼합됨에 따라 기울기 값은 감소하였다. 먼지입자를 제외한 오염입자와 smoke 입자는 음의 값을 보였다. 광흡수 특성의 차이를 파악하기 위하여 1020 nm에서의 단산란알베도 값을 보정하였다. 보정된 단산란알베도와 기울기 값을 합하여 MAF를 도출하였다. MAF는 오염입자와 smoke 입자는 -1, 먼지입자는 1.5의 값을 보였으며, 서로 다른 에어로졸 종류별로 광흡수 특성이 높을수록 낮은 값의 분포를 보였다.

• 한국태양에너지학회 논문집
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• 제30권5호
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• pp.107-114
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• 2010

Understanding of reflectance of solar concentrators is important for assessing concentration performance. However inaccurate data about refractive indices of constituent materials and dust accumulation on the surface often prevent figuring out reflectance variations. The current study proposes an approach calculating concentrator reflectance based on the refractive index of glass obtained from reflectance and transmittance measurements. This approach improved accuracy of solar-averaged reflectance from 2.9% to 0.4% compared to the use of existing reference data. Reflectance variations with incidence angles are negligible up to $60^{\circ}C$ at various glass thicknesses. When concentrators are contaminated with dust during 2 months specular reflectance loss of vertically exposed concentrators is less than 7%. However for horizontally exposed concentrators the loss significantly increases up to 40% while dependence of reflectance on incidence angles becomes strong. Measurements of hemispherical reflectance indicate that 80 percentage of the loss comes from scattering rather than absorption by dust. Data of refractive index and reflectance provided in the current study will help estimate or model the concentrated solar flux.

• 천문학회보
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• 제41권1호
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• pp.48.1-48.1
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• 2016

Polarimetric study of light scattering from cometary dust particles can provide us opportunity to decipher their characteristics, such as sizes, structures, compositions of dust grains, etc. Herein, we present the results of our polarimetric study of long-period comet, C/2013 US10 (Catalina), in optical and near-infrared wavelengths which appeared at large phase angle (52.7 degrees) around the mid-December, 2015. We performed polarimetric and spectroscopic observations with HONIR, attached to the 1.5-m telescope at Higashi-Hiroshima Observatory, on UT 2015 December 17-18 and also obtained optical imaging data sets by the Ishigakijima Astronomical Observatory (IAO) and Okayama Astrophysical Observatory (OAO) taken between 2014-2015. By measuring the intensities of gas emission lines with respect to dust continuum and considering transmittance of each filter, we estimated that the percentages of gas contamination are approximately 10 percents in $R_C$-band and 3 percents in $I_C$-band. With these results, we derive the degree of linear polarization scattered solely from dust components in the coma. At this presentation, we will compare the phase-angle dependence of the degree of linear polarization with those of previous archive data in a wide coverage of wavelengths from $R_C$-band to $K_S$-band. Finally, we are supposed to discuss the spatial variations in polarization within the coma.

• 천문학회보
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• 제37권2호
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• pp.99.1-99.1
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• 2012

We report the results of our analysis of far ultraviolet (FUV) observations made for the broad region around the ${\alpha}$ Vir (Spica) including the interaction zone of the Loop I and the Local Bubble. We employed the datasets of the GALEX and the FIMS, which made observations at similar FUV wavelengths. First, we noted that the GALEX image was enhanced in the southern region where the interaction zone exists. We attribute this enhanced FUV emission to dust scattering of the stellar photons, mostly from the background field stars with small contributions from the central star Spica. While the region is optically thin in general, the FUV intensity did not correlate well with the dust extinction level, indicating that the local radiation field has significant fluctuations. On the other hand, the GALEX FUV intensity well with the $H{\alpha}$ intensity as well as the dust extinction level in the northern part. In fact, the neutral hydrogen column density correlated very well with the dust extinction level throughout the whole region in consideration. The relationship between the neutral hydrogen column density and the color excess was estimated to be ${\sim}7{\times}10^{21}atoms\;cm^{-2}$, which is a little higher than the previous observations made for a diffuse interstellar medium. The spectral analyses of the FIMS observations showed the enhanced C IV emission throughout the whole region, indicating that the C IV emission arises by the interaction of the hot gases with the shell boundaries. A simple model showed that a large portion of the C IV emission comes from the Loop I side of the interaction zone, compared to the Local Bubble side. The FIMS spectrum also showed indications of the molecular hydrogen fluorescence lines for the interaction zone.

• 한국산업보건학회지
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• 제33권2호
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• pp.171-187
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• 2023

Objectives: Aircraft cabin cleaning work is characterized by being performed within a limited time in a narrow and enclosed space. The objective of this study was to evaluate the exposure levels to dust, ultra fine dust(PM2.5) and black carbon(BC) among aircraft cabin cleaners. Methods: Active personal air sampling for respirable dust(n=73) and BC(n=47) was conducted during quick transit cleaning(cabin general and vacuum-specific) and seat cover replacement and total dust and PM2.5 were area-air-sampled as well. Also, size distribution of particle was identified with the cleaning workers targeted. Dusts were collected with PVC filters using gravimetric analysis. The concentration of PM2.5 and the particle size distribution were measured with real-time direct reading portable equipment using light scattering analysis. The concentration of BC was measured by aethalometer(filter-based real-time light absorption analysis instrument). Results: The geometric mean of respirable dust was the highest at vacuum cleaning as 74.4 ㎍/m³, following by replacing seat covers as 49.3 ㎍/m³ and cabin general cleaning as 47.8 ㎍/m³ . The arithmetic mean of PM2.5 was 4.83 ~ 9.89 ㎍/m³ inside the cabin, and 28.5~44.5 ㎍/m³ outside the cabin(from bus and outdoor waiting space). From size distribution, PM_2.5/PM₁₀ ratio was 0.54 at quick transit cleaning and 0.41 at replacing seat covers. The average concentration of BC was 2~7 ㎍/m³, showing a high correlation with the PM2.5 concentration. Conclusions: The hazards concentration levels of aircraft cabin cleaners were very similar to those of roadside outdoor workers. As the main source of pollution is estimated to be diesel vehicles operating at airports, and it is necessary to replace older vehicles, strengthen pollutant emission control regulations, and introduce electric vehicles. In addition, it is necessary to provide as part of airport-inftastructure a stable standby waiting space for aircraft cabin cleaners and introduce a systematic safety and health management system for all workers in the aviation industry.

• 천문학회지
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• 제38권2호
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• pp.125-128
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• 2005

In this paper, we argue that the gigahertz peaked spectrum (GPS) quasars are special blazars, blazars in dense and dusty gas enviornment. The ROSAT detection rate of GPS quasars is similar to that of flat spectrum radio quasars (FSRQs), suggesting that the relativistic jets in GPS quasars are oriented at small angle to the line of sight. Due to strong inverse Compton scattering off infrared photons from dense and dusty nuclear interstellar media in GPS quasars, most of them may have significant soft gamma-ray and X-ray emission, which is consistent with ASCA X-ray observations. Because Compton cooling in GPS quasars is stronger than that in FSRQs, synchrotron emission in GPS quasars may less dominate over thermal emission of the accretion disk and hot dust, hence most GPS quasars show low optical polarization and small variability, consistent with observations. We suggest that it is the significant radio emission of electron/positron pairs produced by the interaction of gamma-rays with the dense gas and dust grains in GPS quasars that makes GPS quasars show steep radio spectra, low radio polarization, and relatively faint VLBI/VLBA cores. Whether GPS quasars are special blazars can be tested by gamma-ray observations with GLAST in the near future, with the detection rate of GPS quasars being similar to that of FSRQs.

• Asian Journal of Atmospheric Environment
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• 제4권3호
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• pp.115-140
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• 2010

Great concerns about atmospheric aerosols are attributed to their multiple roles to atmospheric processes. For example, atmospheric aerosols influence global climate, directly by scattering or absorbing solar radiations and indirectly by serving as cloud condensation nuclei. They also have a significant impact on human health and visibility. Many of these effects depend on the size and composition of atmospheric aerosols, and thus detailed information on the physicochemical properties and the distribution of airborne particles is critical to accurately predict their impact on the Earth's climate as well as human health. A single particle analysis technique, named low-Z particle electron probe X-ray microanalysis (low-Z particle EPMA) that can determine the concentration of low-Z elements such as carbon, nitrogen and oxygen in a microscopic volume has been developed. The capability of quantitative analysis of low-Z elements in individual particle allows the characterization of especially important atmospheric particles such as sulfates, nitrates, ammonium, and carbonaceous particles. Furthermore, the diversity and the complicated heterogeneity of atmospheric particles in chemical compositions can be investigated in detail. In this review, the development and methodology of low-Z particle EPMA for the analysis of atmospheric aerosols are introduced. Also, its typical applications for the characterization of various atmospheric particles, i.e., on the chemical compositions, morphologies, the size segregated distributions, and the origins of Asian dust, urban aerosols, indoor aerosols in underground subway station, and Arctic aerosols, are illustrated.