• Resources Recycling
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• v.24 no.6
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• pp.24-30
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• 2015

The sulfuric acid leaching of ferromanganese dust was studied. The effect of acid concentration, reaction temperature, stirring rate, particle size and solid to liquid ratio on Mn and Fe extraction in the solution were investigated. It was found that the leaching rate of Mn and Fe increased with increasing reaction temperature and sulfuric acid concentration. Examination of data by shrinking core model suggested that the leaching rate is controlled by chemical reaction at the surface of particle. The activation energy for the leaching reaction of Mn and Fe were calculated to be 79.55 kJ/mol and 77.48 kJ/mol, respectively.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.355-358
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• 2015

We have conducted a near-infrared monitoring campaign at the UK InfraRed Telescope (UKIRT), of the Local Group galaxy M33. The main aim was to identify stars in the very final stage of their evolution, and for which the luminosity is more directly related to the birth mass than the more numerous less-evolved giant stars that continue to increase in luminosity. The pulsating giant stars (AGB and red supergiants) are identified and their distributions are used to derive the star formation rate as a function of age. These stars are also important dust factories; we measure their dust production rates from a combination of our data with Spitzer Space Telescope mid-IR photometry. The mass-loss rates are seen to increase with increasing strength of pulsation and with increasing bolometric luminosity. Low-mass stars lose most of their mass through stellar winds, but even super-AGB stars and red superginats lose ~40% of their mass via a dusty stellar wind. We construct a 2-D map of the mass-return rate, showing a radial decline but also local enhancements due to agglomerations of massive stars. By comparing the current star formation rate with total mass input to the ISM, we conclude that the star formation in the central regions of M33 can only be sustained if gas is accreted from further out in the disc or from circum-galactic regions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.5-8
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• 2019

Recently, we have been demanding the comfort of the indoor environment due to environmental problems such as fine dust and yellow dust. In addition it is pursuing the most pleasant indoor environment for humans. In this study, we designed and implemented monitoring systems and mobile applications to enable information such as room temperature and humidity. Open source software and open source hardware are required to design and implement the systems proposed in this study. In this study, the systems implemented used a bluetooth module, a light sensor, and a temperature and humidity sensor. In the future, we expect to be a basic study of systems that can operate dehumidifiers, warm-air fans, fans and humidifiers using motors and optimize indoor environment.

• The Bulletin of The Korean Astronomical Society
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• v.33 no.2
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• pp.35.1-35.1
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• 2008

• Allergy, Asthma & Immunology Research
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• v.10 no.6
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• pp.675-685
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• 2018

Purpose: This study aims to determine the efficacy and safety of house dust mite (HDM)-sublingual immunotherapy (SLIT) in elderly patients with AR. Methods: A total of 45 patients aged ${\geq}60years$ with HDM-induced AR who had ${\geq}3$ A/H ratio on skin prick test and/or ${\geq}0.35IU/L$ to both Dermatophagoides farinae and Dermatophagoides pteronyssinus by ImmunoCAP were enrolled in 4 university hospitals. To evaluate additional effects of HDM-SLIT, they were randomized to the SLIT-treated group (n = 30) or control group (n = 15). Rhinoconjunctivitis total symptom score (RTSS), rhinoscopy score, Korean rhinoconjunctivitis quality of life questionnaire, rhinitis control assessment test, asthma control test scores, and adverse reactions, were assessed at the first visit (V1) and after 1 year of treatment (V5); for immunological evaluation, serum levels of HDM-specific immunoglobulin A/IgE/IgG1/IgG4 antibodies and basophil response to HDMs were compared between V1 and V5 in both groups. Results: There were no significant differences in demographics, RTSS, skin reactivity to HDMs, or serum total/specific IgE levels to HDMs (P > 0.05, respectively) between the 2 groups. Nasal symptom score and RTSS decreased significantly at year 1 in the 2 groups (P < 0.05). There were no significant differences in percent decrease in nasal symptom score and RTSS at year 1 between the 2 groups (P > 0.05); however, rhinoscopic nasal symptom score decreased significantly in the SLIT-treated group (P < 0.05). Immunological studies showed that serum specific IgA levels (not specific IgE/IgG) and CD203c expression on basophils decreased significantly at V5 in the SLIT-treated group (P = 0.011 and P = 0.001, respectively), not in the control group. The control group required more medications compared to the treatment group, but there were no differences in adverse reactions. Conclusions: It is suggested that HDM-SLIT for 1 year could induce symptom improvement and may induce immunomodulation in elderly rhinitis patients.

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.157-161
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• 2017

The dusty torus of Active Galactic Nuclei (AGNs) is one of the important components for the unification theory of AGNs. The geometry and properties of the dusty torus are key factors in understanding the nature of AGNs as well as the formation and evolution of AGNs. However, they are still under discussion. Infrared observation is useful for understanding the dusty torus as thermal emission from hot dust with the dust sublimation temperature (~ 1500 K) has been observed in the infrared. We have analyzed infrared spectroscopic data of low-redshift and high-redshift quasars, which are luminous AGNs. For the low-redshift quasars, we constructed the spectral energy distributions (SEDs) with AKARI near-infrared and Spitzer mid-infrared spectra and decomposed the SEDs into a power-law component from the nuclei, silicate features, and blackbody components with different temperatures from the dusty torus. From the decomposition, the temperature of the innermost dusty torus shows the range between 900-2000 K. For the high-redshift quasars, AKARI traced rest-frame optical and near-infrared spectra of AGNs. Combining with WISE data, we have found that the temperature of the innermost dusty torus in high redshift quasars is lower than that in typical quasars. The hydrogen $H{\alpha}$ emission line from the braod emission line region in the quasars also shows narrow full width at half maximum of $3000-4000km\;s^{-1}$. These results indicate that the dusty torus and the broad emission line region are more extended than those of typical quasars.

• Journal of the Ergonomics Society of Korea
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• v.25 no.2
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• pp.173-180
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• 2006

An ergonomic study of school environment and school desks and chairs was conducted in Incheon metropolitan area. Total of 1,145 students from 11 schools participated in questionnaire survey and ergonomic evaluation of school desks and chairs was performed to study structural appropriateness and usability. Results of the study revealed that overall levels of school environment in terms of noise and dust density in the air were higher than safety standard. Desks and chairs were not properly designed with consideration of student's anthropometric characteristics. Prompt improvement of school environment and re-designing of school furniture are required in order to prevent reduced performance in study and physical disorders such as musculoskeletal disorders.

• KSBB Journal
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• v.29 no.4
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• pp.285-296
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• 2014

Although the problems of the algal blooms have been world-widely observed in freshwater, estuary, and marine throughout the year, it is not yet certain what are the basic causes of such blooms. Consequently, it is very difficult to predict when and where algal blooms occur. The constituents of the Asian dust are in a good agreement with the elements required for the algal growth, which suggests some possible relationship between the algal blooms and the Asian dust. There have been frequently algal blooms in drinking water from rivers or lakes. However, there is no any algal blooms in upwelling waters where the Asian dust cannot penetrate into the soil due to its relatively weak settling velocity (size of particles, $4.5{\pm}1.5{\mu}m$), which implies the possible close relationship of the Asian dust with algal blooms. The present initiative study is thus intended firstly in Korea to illustrate such a relationship by reviewing typical previous studies along with 12 years of weekly iron profiles (2001~2012) and two slant culture experiments with the dissolved Asian dust. The result showed bacterial suspected colonies in the slant culture experiment that are qualitatively in a good agreement with the recent Japanese studies. Since the diatoms require cheap energy (8%) compared to other phytoplankton (100%) to synthesize their cell walls by silicate, the present results can be used to predict algal blooms by diatoms if the concentrations of iron and silicate are available during spring and fall. It can be postulated that the algal blooms occur only if the environmental factors such as light, nutrients, calm water surface layer, temperature, and pH are simultaneously satisfied with the requirements of the micronutrients of mineral ions supplied by the Asian dust as enzymatic cofactors for the rapid bio-synthesis of the macromolecules during algal blooms. Simple eco-friendly methods to regulate the algal blooms are suggested for the initial stage of blooming with limited area: 1) to cover up the water surface with black curtain and inhibit photosynthesis during the day time, 2) to blow air (20.9%) or pure oxygen into the bottom of the water and inhibit rubisco for carbon uptake and nitrate reductase for nitrogen uptake activities in algal growth during the night, 3) to eliminate the resting spores or cysts by suction of bottom sediments as deep as 5 cm to prevent the next year germinations.

• Journal of Environmental Science International
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• v.21 no.2
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• pp.217-231
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• 2012

Hourly concentrations of $PM_1$, $PM_{2.5}$ and $PM_{10}$, were investigated at Gangneung city in the Korean east coast on 0000LST October 26~1800LST October 29, 2003. Before the intrusion of Yellow dust from Gobi Desert, $PM_{10}$($PM_{2.5}$, $PM_1$) concentration was generally low, more or less than 20 (10, 5) ${\mu}g/m^3$, and higher PM concentration was found at 0900LST at the beginning time of office hour and their maximum ones at 1700LST around its ending time. As correlation coefficient of $PM_{10}$ and $PM_{2.5}$($PM_{2.5}$ and $PM_1$, and $PM_{10}$ and $PM_1$) was very high with 0.90(0.99, 0.84), and fractional ratios of $(PM_{10}-PM_{2.5})/PM_{2.5}((PM_{2.5}-PM_1)/PM_1)$ were 1.37~3.39(0.23~0.54), respectively. It implied that local $PM_{10}$ concentration could be greatly affected by particulate matters of sizes larger than $2.5{\mu}m$, and $PM_{2.5}$ concentration could be by particulate matters of sizes smaller than $2.5{\mu}m$. During the dust intrusion, maximum concentration of $PM_{10}$($PM_{2.5}$, $PM_1$) reached 154.57(93.19, 76.05) ${\mu}g/m^3$ with 3.8(3.4, 14.1) times higher concentration than before the dust intrusion. As correlation coefficient of $PM_{10}$ and $PM_{2.5}$(vice verse, $PM_{2.5}$, $PM_1$) was almost perfect high with 0.98(1.00, 0.97) and fractional ratios of $(PM_{10}-PM_{2.5})/PM_{2.5}((PM_{2.5}-PM_1)/PM_1)$ were 0.48~1.25(0.16~0.37), local $PM_{10}$ concentration could be major affected by particulates smaller than both $2.5{\mu}m$ and $1{\mu}m$ (fine particulate), opposite to ones before the dust intrusion. After the ending of dust intrusion, as its coefficient of 0.23(0.81, - 0.36) was very low, except the case of $PM_{2.5}$ and $PM_1$ and $(PM_{10}-PM_{2.5})/PM_{2.5}((PM_{2.5}-PM_1)/PM_1)$ were 1.13~1.91(0.29~1.90), concentrations of coarse particulates larger than $2.5{\mu}m$ greatly contributed to $PM_{10}$ concentration, again. For a whole period, as the correlation coefficients of $PM_{10}$, $PM_{2.5}$, $PM_1$ were very high with 0.94, 1.00 and 0.92, reliable regression equations among PM concentrations were suggested.

• Journal of the Korean Magnetics Society
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• v.15 no.5
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• pp.270-275
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• 2005

Dust cores (compressed powder cores) of $Fe-6.0wt\%Si$ alloy with a size of $35\~180\;{\mu}m$ in diameter have been prepared by phosphate coatings and annealings at $600\~900^{\circ}C$ for 1 h in nitrogen atmosphere. Further the magnetic and mechanical properties of the powder cores were investigated. As a general trends, the compressive strength and core loss decreased with the increase in annealing temperature. When annealed at $800^{\circ}C$, the compressive strength was 15 kgf, the permeability and quality factor were 74 and 26, respectively. Moreover the core loss at 50 kHz and 0.1 T induction was $750\;mW/cm^3$, and the percent permeability under the static field of 50 Oe was estimated to be about 78. In addition, the cut-off frequency in the cure representing the frequency dependence of effective permeability was measured to be around 200 kHz. These properties of the $Fe-6.0wt\%Si$ alloy dust cores could be considered to be due to the good insulation effect of iron-phosphate coats, the decrease in magnetocrystalline anisotropy and saturation magnetostriction and the increase in electric resistivity.