• 천문학회지
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• 제44권1호
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• pp.13-21
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• 2011

We model dust around Herbig Ae/Be stars using a radiative transfer model for multiple isothermal circumstellar dust shells to reproduce the multiple broad peaks in their spectral energy distributions (SEDs). Using the opacity functions for various types of dust grains at different temperatures, we calculate the radiative transfer model SEDs for multiple dust shells. For eight sample stars, we compare the model results with the observed SEDs including the Infrared Space Observatory (ISO) and AKARI data. We present model parameters for the best fit model SEDs that would be helpful to understand the overall structure of dust envelopes around Herbig Ae/Be stars. We find that at least four separate dust components are required to reproduce the observed SEDs. For all the sample stars, two innermost dust components (a hot component of 1000-1500 K and a warm component of 300-600 K) with amorphous silicate and carbon grains are needed. Crystalline dust grains (corundum, forsterite, olivine, and water ice) are needed for some objects. Some crystalline dust grains exist in cold regions as well as in hot inner shells.

• 한국산업융합학회 논문집
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• 제21권3호
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• pp.133-139
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• 2018

Precipitator is the most widespread device used to separate dust particles from the exhaust gas. In the shipyard, welding umbrellas, spark protection covers, and ventilators are not purchased and used for the work place to capture the flames and high temperature metal dust generated during the gardening process. In particular, a thorough analysis of design factors, such as capture rate, collection capacity calculation, filter speed, and materials selection, is required since spatial constraints are followed by structures, etc. In this study, conceived to address problems such as this cyclone and filtration filter system that combines all-in-one gausing collector prototype. Assessed through interpretation through the validity of the design and reliability.

• Journal of Biosystems Engineering
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• 제36권3호
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• pp.204-210
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• 2011

This study developed the cyclone conveying system using roughage cutter for the round bale reported in the previous papers. Performance tests were conducted whether it can easily separate dust from roughage such as rice straws and it can transport roughages from cutter to TMR mixer. In addition, the airflow patterns in the cyclone conveying system were investigated using CFD code (FLUENT 6.2) for various velocities of dust collection fan. The cyclone conveying system was designed based on dried rice straws with a diameter of 1,340 mm, a cylinder length of 1,220 mm, a cone length of 850 mm and the current velocity of the dust collection fan was 15~20 m/s. It was found that transporting of roughage from cutter to TMR mixer and the separation of dust were satisfactory, and the dust removal rate of rice straws was around 31.9%. CFD analysis showed that, at the blowing fan velocity of 11.6 m/s, the airflow velocity inside the dust collector increased as velocity of the dust collection fan increased, but the airflow patterns inside the dust collector were all much the same.

• Journal of Astronomy and Space Sciences
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• 제28권4호
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• pp.253-260
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• 2011

To reproduce the multiple broad peaks and the fine spectral features in the spectral energy distributions (SEDs) of T Tauri stars, we model dust around T Tauri stars using a radiative transfer model for multiple isothermal circumstellar dust shells. We calculate the radiative transfer model SEDs for multiple dust shells using the opacity functions for various dust grains at different temperatures. For six sample stars, we compare the model results with the observed SEDs including the Spitzer spectral data. We present model parameters for the best fit model SEDs that would be helpful to understand the overall structure of dust envelopes around classical T Tauri stars. We find that at least three separate dust components are required to reproduce the observed SEDs. For all the sample stars, an innermost hot (250-550 K) dust component of amorphous (silicate and carbon) and crystalline (corundum for all objects and forsterite for some objects) grains is needed. Crystalline forsterite grains can reproduce many fine spectral features of the sample stars. We find that crystalline forsterite grains exist in cold regions (80-100 K) as well as in hot inner shells.

• 한국산학기술학회논문지
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• 제20권12호
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• pp.519-524
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• 2019

본 연구에서는 대풍량 곡물건조기에 사용되는 수평형 집진기의 집진효율 향상과 최적화를 위한 연구의 선행과정으로 Computational Fluid Dynamics(CFD)를 이용하여 집진기 내부의 유동 특성 분석과 원뿔형 허브의 각 변화가 집진기의 집진성능에 미치는 영향을 해석하였다. 최근 집진기 입구에 원뿔형 허브와 고정 베인을 설치하여 선회유동(Swirl Flow)을 발생시켜 이물질을 공기와 분리시키는 수평형 사이클론 집진기(Horizontal type Cyclone Dust collector)가 개발되었다. 이 집진기는 크기가 비교적 작고 설치가 용이하고 비교적 배압이 낮아 추가 동력을 필요로 하지 않으며 베인의 선회력을 이용하기 때문에 대풍량 배습용 송풍기에도 적용할 수 있는 장점을 가지고 있다. 그러나 수평형 집진기 형상으로 인해 발생하는 집진기 내부의 배압 문제와 분진 퇴적 문제를 해결하기 위해서 3차원 유동해석을 이용하여 집진기 내부 형상 변화에 따른 유동 특성에 관한 연구를 진행하였다. 실제 곡물건조기에 적용 가능한 수평형 집진기 설계를 위한 기초 자료를 제공하였으며, 향후 연구 예정인 고정 베인 설계, 주분리관 및 중간분리관의 설계에 적용하고자 한다.

• 한국농공학회논문집
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• 제50권4호
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• pp.39-50
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• 2008

A study on fugitive dust dispersion was conducted at Saemanguem reclaimed area located at the west coastal area of Jeon-buk Province Total reclaimed area is 40,100ha developed by building a 33km long sea dike through Gunsan, Gimje, and Buan. (Land: 28,300ha, Fresh Water Lake: 11,800ha) After this area was completely reclaimed in 2006, there has been high possibility of dust generation and dispersion to the neighboring area. The dust generated at the reclaimed land was composed mainly of minerals with high salinity, and it could make harmful effect on crop production as well on to human's health such as eye irritation and respiratory disease. Especially, when those aerosol particles are reached on the leaves of farm crops, the photosynthesis and respiration of the plants can be under restraint resulting in the decrease of agricultural productivity of the nearby farm areas. Furthermore, highly concentrated salty particles can directly damage the leaf cells. In this study, field experiment has been conducted to regularly measure the locally suspended dust particles and analyze how they were dispersed to the neighboring areas. The collected dust particles were analyzed to examine theirs sizes, concentrations, and components. The SPSS statistical program was also used to separate the dust concentration generated by the reclaimed land from the total dust concentration measured at the measuring locations.

• 한국의류학회지
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• 제26권6호
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• pp.811-820
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• 2002

The physical responses and subjective sensations of different cleanroom garments were compared in order to discover which cleanroom garment design could minimize pollution of the working environment by dust from the worker, maintain a pleasant microclimate and provide effective thermoregulation. A. Coverall with non-detachable hood, kimono sleeves (front), raglan sleeves (back), raschell net on the bodice B. Coverall with detachable hood, kimono sleeves (front), raglan sleeves (back), raschell net on the bodice C. Separate top with non-detachable hood, kimono sleeves (front), raglan sleeves (back), raschell net on the bodice D. Coverall with non-detachable hood, set-in sleeves, raschell net on the bodice E. Coverall with non-detachable hood, raglan sleeves (back), l00% cotton inner wear (upper body) The results of the experiment were as follows. Because the hood covered the shoulder and the chest areas, the chests temperature of the worker wearing garment E was quite higher than those wearing other garment designs. For fabric that has been coated in order to prevent dust, layered designs should be avoided in order to prevent skin temperature from rising. Compared with layers of underwear, it would be more effective to attach a see-through raschell net which clings to the body. Thermal sensations were also highest in garment E, reinforcing the finding that layered designs should be avoided. Through the experiment, it was found that a new material coverall with a non-detachable hood was effective in minimizing dust, suppressing skin temperature increases, maintaining a superior microclimate and providing pleasant subjective sensations.

• 한국대기환경학회지
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• 제6권1호
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• pp.1-10
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• 1990

The purpose of the study was to analyze air quality in underground shopping centers using pattern recognition methods. In order to perform this, the concentraion of air pollutants such as $CO, NO_2, NO_x, SO_2$, and particulate matters was measured at the 11 different shopping centers in Seoul metropolitan area and the total of 47 samples were obtained at random based on the size of shopping centers. To introduce a new concept of the "average concentration" for the indoor air quality analyses, the various multivariate statistical analyses have been studied. Thus, a cluster analysis was applied to separate the samples into pseudo-patterns and a disjoint principal component analysis was used to generate homogeneous patterns after removing outliers from the pseudo-patterns. The 6 homogeneous patterns were then obtained as follows:the first pattern was a group of clean sites;the second a group of sites having high dust concentration;the third a group of sites having high dust and $NO_x$ concentration;the fourth a group of sites having low dust and $SO_2$ concentraion and high CO concentration;the fifth a group of sites having high $NO_2 and SO_2$ concentration;and the final a group of miscellaneous sites. Thus, the average concentration could be estimated for each pattern.h pattern.

• 열처리공학회지
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• 제36권1호
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• pp.22-32
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• 2023

In general, when scrap is dissolved in an electric arc furnace, the amount of electric furnace steel dust (EAFD) generated is about 1.5% of the scrap charge amount, and the electric furnace steel dust collected by the bag filter is charged into the Rotary Kiln or Rotary Hearth Furnace (RHF), and the zinc component is recovered as crude zinc oxide, at which time a clinker of Fe-Base is generated. In this research, first, for the efficient resource conversion of electric furnace steel dust, a reduction and roasting experiment was conducted and the reaction kinetics was examined. As a result of the experiment, it was observed that the reduction and roasting reaction was actively conducted in the range of 1100~1150℃, and melting occurred in the range of 1250℃. In the past, this clinker was widely used as a roadbed material for road construction and an Fe-Source for cement production, but in recent years, it has been mainly reclaimed due to strengthening environmental standards. However, landfill treatment is by no means a desirable treatment method due to environmental pollution caused by leachate, expensive landfill costs, and waste of Fe resources. Therefore, in order to more actively recycle the Fe component in the clinker, first of all the clinker was pulverized into an optimal particle size, and anthracite and binder (starch) were added to the magnetic material obtained by specific gravity and magnetic separation for briquet. As a experimental results, it was possible to efficiently separate clinker as Fe component and other slag component by specific gravity and magnetic force. As a results of loading and dissolving the manufactured briquet clinker in an electric arc furnace, it was observed that the unit of power and production yield were clearly improved and the carbon addition effect in molten metal was also somewhat.

• 생물환경조절학회지
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• 제32권4호
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• pp.285-294
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• 2023

미세먼지 저감을 위한 가장 현실적이고 효율적인 방법은 도시 지역의 녹지 조성으로 이에 대한 관심이 증가하고 있다. 국내 도시 특성상 도로변에 녹지를 조성할 경우 별도의 녹지 조성없이 대기 중에 떠다니는 미세먼지나 차량에서 발생한 미세먼지가 도로변 가로수에 흡착돼 미세먼지 저감에 효과적이다. 하지만, 미세먼지는 대기 중에 부유하며 존재하고 지역별 미세먼지 농도 차이와 식재 배치 차이로 인해 때문에 미세먼지 농도 현장 측정 및 대기 중 이동 경로에 대해 예측과 도로 식재 배치 유형별 미세먼지 저감효과에 대한 규명이 어려운 실정이다. 이에 본 연구에서는 CFD 시뮬레이션을 이용하여 도로 중앙분리대와 가로수의 식재 유형별로 미세먼지 농도변화 및 미세먼지 저감효과를 분석하였다. 분석 결과 미세먼지 저감을 위해서는 중앙분리대에 식재가 있는 것이 미세먼지 저감 효과가 탁월할 것으로 보이며 가로수에 교목과 관목을 동시에 설치하는 것이 바람직하다고 판단된다. 본 결과를 바탕으로 도시 대기환경 개선을 위한 가로녹지 식재 기준(가이드라인) 마련에 효과적으로 이용될 것으로 판단되며 향후 도시 도로변 미세먼지 저감 연구 진행에 선행연구의 참고자료로 활용될 수 있을 것으로 기대된다.