• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.38.1-38.1
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• 2019

The formation and evolution of galaxies is known to be fundamentally linked to the local environment in which they reside. In the highest-density cluster environments, galaxies tend to be more massive, have lower star formation rates and dust content, and a higher fraction have elliptical morphologies. The stellar populations of these cluster galaxies are older implying that they formed the bulk of their stars much earlier and have since evolved passively. Quantifying the specific environmental factors that contribute to shaping cluster galaxies over the Hubble time and measuring their early evolution can only be accomplished by directly tracing the galaxy growth in young clusters and forming porto-clusters. In this talk, I will present a novel technique designed to map out the total dust obscured star formation relative to where existing stars lie. I will demonstrate that this technique can be used 1) to determine if/where/when the activity is heightened or suppressed in dense cluster environment; 2) to measure the total mass and spatial distribution of stellar populations; and 3) to better inform theoretical models. Our ongoing work to extend this analysis out to protoclusters (z~2-4) will be discussed.

• Journal of Bio-Environment Control
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• v.32 no.4
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• pp.285-294
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• 2023

The importance of urban green space creation is increasingly recognized as the most realistic and efficient approach for fine dust mitigation in urban areas. Particularly considering the characteristics of domestic cities, the application of buffer green spaces along roads can maximize the efficiency of fine dust reduction without the need for separate green space creation. Accordingly, this study analyzed the fine dust mitigation effects based on the types of plantings in the central dividers and roadside trees in Jeonju City, Jeollabuk-do. To do this, we controlled various external variables of urban space and considered the planting arrangement types in the central dividers, carrying out the analysis using a CFD simulation. The simulation results confirmed that the central dividers with plantings demonstrated more effective ultrafine dust reduction than those without. Moreover, the arrangement of roadside trees showed a greater ultrafine dust reduction effect when adopting a multilayered structure compared to a single layer. Based on these findings, we concluded that installing both trees and shrubs simultaneously in the central dividers and along roads was effective for ultrafine dust mitigation. On this basis, we quantified the dust reduction effects of plants in urban street environments and proposed planting guidelines for roadside green spaces to improve air quality.

• Journal of Bio-Environment Control
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• v.21 no.4
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• pp.362-371
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• 2012

Objective of this research was to secure the information on physical and chemical properties of peatmoss and coir dust. To achieve this, 6 kinds of peatmoss and 10 kinds of coir dust currently used in the country as the root medium components in plant factories were collected and analysed. The mean ${\pm}$ standard deviation (SD) of total porosity and container capacity in peatmoss and coir dust were $79.6{\pm}5.04$ and $83.6{\pm}6.18%$, and $69.9{\pm}10.17$ and $65.9{\pm}3.46%$, respectively. These indicate that peatmoss has higher water holding capacity than coir dust and the characteristics are highly varied among peatmoss. The 4 out of 5 kinds of peatmoss had lower than 10%, but coir dust had 12~26%, of air-filled porosity. The percentage of easily available water and buffering water in peatmoss and coir dust was 18~22 and 11~16% and 9~13 and 5.5~7.5%, respectively. These results indicate that precise irrigation is required when coir dust is used as the root medium. The ranges of pH and electrical conductivity (EC) were 3.46~4.17 and $0.137{\sim}0.253dS{\cdot}m^{-1}$ in peatmoss and 5.31~6.48 and $0.250{\sim}0.1.580dS{\cdot}m^{-1}$ in coir dust. However, $0.563{\pm}0.83dS{\cdot}m^{-1}$ in mean ${\pm}$SD of coir dust EC indicates that it is higher than that of peatmoss, and the coir dust are highly varied in EC. The cation exchange capacity of peatmoss was 3 to 4 times as high as that of coir dust. The coir dust had higher $NO_3$ and $PO_4$ and lower $NH_4$ than peatmoss. The K and Na concentrations in coir dust were extremely high indicating that these ions caused the rising in EC. The percentage of hot water and alkali extracts of peatmoss were 6.67~16.37 and 0~38%, whereas those of coir dust were 30.0~65.1 and 23.1~70.3%. These results mean that possible existence of growth inhibiting materials in coir dust.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.98.2-98.2
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• 2012

We firstly present the unified Far-UV continuum map of the Taurus-Auriga-Perseus (TPA) complex, one of the largest local associations of dark cloud located in (l, b)=([154,180], [-28, -2]), by merging both FIMS and GALEX. The FUV continuum map shows that dust extinction correlate well with the FUV around the complex. It shows strong absorption in FUV toward the dense Taurus cloud while it does not in California cloud. It turned out that it is related to the relative location of each cloud and Perseus OB2 association. We also present some results of dust scattering simulation based on Monte Carlo Radiative Transfer technique (MCRT). Through this dust scattering simulation, we have derived the scattering parameter for this region, albedo(a)=$0.42^{+0.05}{_{-0.05}}$, asymmetry factor(g)=$0.47^{+0.11}{_{-0.27}}$. The optical parameters we obtained seem reasonable compared to the theoretical model values ~0.40 and ~0.65 for the albedo and the phase function though the phase function is rather small. Using the result of simulation, we figured out the geometries of each cloud in the complex region, especially their distances and thicknesses. Our predictions from the results are in good agreement with the previous studies related to the TPA complex. For example, the Taurus cloud is within ~200pc from the Sun and the Perseus seems to be multi-layered, at least two. The California cloud is more distant than the other cloud on average at ~350 pc and Auriga cloud seems to be between the Taurus cloud and the eastern end of the California cloud. We figured out that across the TPA complex region, there might be some correlation between the LSR velocity and the distance to each cloud in the complex.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.37.4-38
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• 2016

Based on the $850{\mu}m$ dust continuum data from James Clerk Maxwell Telescope (JCMT)/SCUBA-2, we compare overall properties of Planck Galactic Cold Clumps (PGCCs) in the ${\lambda}$ Orionis cloud with PGCCs in other molecular clouds, Orion A and Orion B. The Orion A and Orion B clouds are well known active star-forming region, while, ${\lambda}$ Orionis cloud has a different environment associating with prominent OB associations and a giant H II region. PGCCs in the ${\lambda}$ Orionis cloud have higher dust temperatures (Td~16.08 K) and lower values of dust emissivity (${\beta}{\sim}1.65$) than Orion A and Orion B clouds. In addition, we found the lowest detection rate (16 %, 8 out of 50) of PGCCs at $850{\mu}m$ in the ${\lambda}$ Orionis cloud while among three regions; Orion A and Orion B clouds show much higher detection rates of ~ 76 % (23 out of 30) and 56 % (9 out of 16), respectively. The detected 8 PGCCs in the ${\lambda}$ Orionis cloud have substructures and we identified 15 cores. The cores also show much lower median values of size (~0.08 pc), column density (~ ), number density (~ ), and mass (~ ) compared with other cores in the Orion A and Orion B clouds. These core properties in the ${\lambda}$ Orionis cloud can be attributed to the compression and external heating by the nearby H II region, which may prevent the PGCCs from forming gravitationally bound structures and eventually disperse them. These results well present the negative stellar feedback to core formation.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.265-270
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• 2012

Many observations have found evidence of the presence of a large number of heavily obscured Active Galactic Nuclei (AGNs). However, the nature of this population is only poorly understood because heavy obscuration by dust prevents one from finding them at optical wavelengths. Mid-infrared AGN searches can overcome this obstacle by penetrating through dust and by detecting direct emission from the dust torus. Thus, we can identify most of the AGN population, including type-2 and buried AGNs. Using the AKARI mid-infrared all-sky survey, we performed an AGN search in the nearby universe. Utilizing the 2MASS photometry, we selected mid-infrared-excess sources and carried out near-infrared spectroscopic observations in the AKARI Phase 3. During these follow-up observations, we have found three galaxies that show strong near-infrared red continuum from hot dust with a temperature of about 500 K, but do not show any AGN features in other wavelengths. The most suitable explanation of near-infrared continuum is the presence of central AGNs. Therefore, we conclude that they are AGNs obscured by dust. We performed X-ray observations of the two galaxies with SUZAKU. No detections in the 0.4-10 keV suggest that the column density may be much higher than $N_H=10^{23.5}cm^{-2}$. Comparing the masses of the host galaxies with those of the SDSS AGNs, we find that the host galaxies of the dusty AGNs discovered with AKARI are less massive populations than those of optically selected AGNs.

• Journal of Korean Society for Atmospheric Environment
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• v.33 no.4
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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.

• Korean Journal of Veterinary Research
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• v.45 no.1
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• pp.105-111
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• 2005

Canine sarcoptic mite (Sarcoptes scabiei var. canis) is ectoparasite which burrow usually in the stratum corneum of the skin of dogs. Antigens from the burrowing mites induce humoral and cellmediated immune responses in the hosts. The effect of antigenecity induced by somatic antigens of house dust mite (Dermatophagoides pteronyssinus) isolated by continuous elution has been evaluated in canine sarcoptic mites infestation. Continuous elution was carried out in 7.5% SDS-PAGE to isolate proteins of common antigens from somatic antigens of house dust mite. These eluted proteins from somatic antigens of house dust mite were confirmed by Western blotting in 7.5% SDS-PAGE, and eluted proteins (65, 60 kDa) were isolated. To evaluate the antigenetic effect of eluted proteins, eight dogs were divided as 4 groups such as non-vaccinated and non-challenged control (Group I), challenged control (Group II), vaccinated (Group III), and vaccinatedandchallenged (Group IV) groups. Group II and IV were artificially infested canine sarcoptic mites. Group III and IV were immunized with eluted proteins (65, 60 kDa). At the 6th week of the vaccination, the antibody titers of Group of IV were statistically significant higher than those of Group II (p<0.05). And antibody titers of Group III were also statistically significant higher than those of Group I (p<0.05). From these result, it is possible to replace somatic antigens of canine sarcoptic mites with eluted proteins from somatic antigens of house dust mites in order to diagnose and prevent the canine sarcoptic mite infestations.

• Journal of the Korean Institute of Gas
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• v.16 no.4
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• pp.32-37
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• 2012

The aim of this study is to evaluate the characteristics of explosion and flame velocity that can be utilized to factories where Mg-Al alloy metal powders are handled in the form of raw materials, products or by-product for similar dust explosion prevention and mitigation. Because the strength of the blast pressure is the result due to flame propagation, flame velocity in dust explosion can be utilized as a valuable information for damage prediction. An experimental investigation was carried out on the influences of content ratio of Mg-Al alloy (mean particle size distribution of 151 to 161 ${\mu}m$). And a model of flame propagation velocity based on the time to peak pressure and flame arrival time in dust explosion pressure, assuming the constant burning velocity, leads to a representation of flame velocity during dust explosion. As the results, the maximum flame velocity of Mg-Al(60:40 wt%), Mg-Al(50:50 wt%) and Mg-Al(40:60 wt%) was estimated 15.5, 18 and 15.2 m/s respectively, and also tend to change with content ratio of Mg-Al.

• Journal of Animal Environmental Science
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• v.9 no.1
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• pp.19-26
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• 2003

This study was carried out to investigate the collecting efficiency of cyclone deduster installed in weaned piglet building in third weeks of age. There are two peaks of high level of dust concentration in piglet house at the time of 09:00~10:00(5,322$\mu g/m^3$) and 19:00~20:00(6,763$\mu g/m^3$), but the peaks of dust concentration in the building used cyclone deduster was decreased to 3,614.8 and 2,229.5$\mu g/m^3$, respectively. Collecting efficiency of total suspended particulate(TSP), particulate matter less than 10$\mu\textrm{m}$(PM 10) and particulate matter less than 2.5$\mu\textrm{m}$(PM 2.5) in weaned piglet building used in cyclone deduster was 38.3%, 32.5, 21.8, respectively. Aerial dust in weaned piglet building by number basis in the range of 0.745~1.08$\mu\textrm{m}$ was 53.5%. But dust distribution over 10$\mu\textrm{m}$ in volume basis was 82.8% and 86.2%. Crude protein of dust was 25.9~32.7%, and it was higher than feed crude protein(22.0%). Heavy metal concentration of dust was also high level compare to that of feed.