• Korean Journal of Materials Research
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• v.26 no.9
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• pp.468-471
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• 2016

$SnO_2:CNT$ thick films for gas sensors were fabricated by screen printing method on alumina substrates and were annealed at $300^{\circ}C$ in air. The nano $SnO_2$ powders were prepared by solution reduction method using tin chloride ($SnCl_2.2H_2O$), hydrazine ($N_2H_4$) and NaOH. Nano $SnO_2:CNT$ sensing materials were prepared by ball-milling for 24h. The weight range of CNT addition on the $SnO_2$ surface was from 0 to 10 %. The structural and morphological properties of these sensing material were investigated using X-ray diffraction and scanning electron microscopy and transmission electron microscope. The structural properties of the $SnO_2:CNT$ sensing materials showed a tetragonal phase with (110), (101), and (211) dominant orientations. No XRD peaks corresponding to CNT were observed in the $SnO_2:CNT$ powders. The particle size of the $SnO_2:CNT$ sensing materials was about 5~10 nm. The sensing characteristics of the $SnO_2:CNT$ thick films for 5 ppm $H_2S$ gas were investigated by comparing the electrical resistance in air with that in the target gases of each sensor in a test box. The results showed that the maximum sensitivity of the $SnO_2:CNT$ gas sensors at room temperature was observed when the CNT concentration was 8wt%.

• Journal of Environmental Science International
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• v.20 no.1
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• pp.147-153
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• 2011

The objectives of this study were to investigate the seasonal characteristics of metallic and ion elements of $PM_{10}$(Particulate matter with aerodynamic diameter ${\leq}10\;{\mu}m$) and the effects of vessels exhaust emission from ships harboring in Busan City. The $PM_{10}$ samples were collected from January 2010 to October 2010 at Dongsam-dong(coastal area), in Busan City. The particulate matters were analyzed for major water soluble ionic components and metals. The ranges of the $PM_{10}$ mass concentrations were from 29.8 ${\mu}g/m^3$ to 47.0 ${\mu}g/m^3$ in Dongsam-dong. The $PM_{10}$ mass concentrations in Dongsam-dong are very similar to Gwangbok-dong during same sampling periods. These results were understood by the effects of the shipping source emitted from ships anchoraging and running. The concentrations of water-soluble ions and metals in the $PM_{10}$ had a level of as high as the order of $SO_4^{2-}$>$NO_3^-$>$Cl^-$ and $NH_4^+$>$Na^+$>$Ca^{2+}$>$K^+$>$Mg^{2+}$, respectively. The correlation coefficients($R^2$) for $SO_4^{2-}/PM_{10}$ and $NH_4^+/PM_{10}$ of were 0.7446 and 0.7784, respectively, and it showed the high correlation with each other.

• Fashion & Textile Research Journal
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• v.17 no.6
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• pp.1004-1012
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• 2015

The purpose of this study is to investigate the loess dyeability of soybean fabric using loess as colorants. Recent days, various textile products such as inner wears, sheets and interior goods are manufactured using materials dyed with loess emphasizing its improved metabolism, anti-bacterial, deodorizing properties, and far infrared ray emissions. Soybean fabric was dyed with loess solution according to concentration of loess, dyeing temperature and dyeing time. To improve washing fastness, soybean fabric and dyed soybean fabric with loess were mordanted by mordanting agents such as sodium chloride(NaCl), Acetic acid(CH₃COOH) and Aluminium Potassium Sulfate(AlK(SO₄)₂·12H₂O). Dyeability and color characteristics of dyed soybean fabric were obtained by CCM observation. Particle size distribution of loess, the dyeability(K/S) of soybean fabric, morphology and washing durability of loess dyed soybean fabric were investigated. The results obtained were as follows; Mean average diameter of loess was 1.08µm. The main components of loess used in this study were silicon dioxide(SiO₂), aluminium oxide(Al₂O₃), and iron oxide(Fe₂O₃). The content of these three component was above 75 weight %. The dyeability of soybean fabric was increased gradually with increasing concentration of loess. The optimum dyeing temperature and dyeing time were 90℃ and 60minutes expectively. The fastness to washing according to concentration of loess and mordanting method indicated good grade result as more than 4 degree in all conditions.

• Fashion & Textile Research Journal
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• v.18 no.4
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• pp.531-539
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• 2016

Charcoal dyed fabrics have been widely used in home textiles and functional clothing due to their anti-statics, antibacterial, deodorization, far infrared emitting and anion releasing. Soybean fiber were regenerated from soybean. Soybean fiber have biodegradable, microbiocidal, non-allergic, and anti-ageing properties. The purpose of this study is to investigate the dyeing characteristics of soybean fabric using charcoal as colorants. Soybean fabrics were dyed with charcoal solution according to concentration of charcoal, dyeing temperature, and dyeing time. To improve washing fastness and investigate mordanting condition, soybean fabric and dyed soybean fabric with charcoal were mordanted by mordanting agents such as $CH_3COOH$(acetic acid), NaCl(sodium chloride) and $AlK(SO_4)_2{\cdot}12H_2O$(Aluminium Potassium Sulfate). Dyeability and color characteristics of charcoal dyed soybean fabric were obtained by computer color matching and SEM morphology analysis. Particle size of charcoal and color fastness were also investigated. The results obtained were as follows; Mean average diameter of charcoal was $1.39{\mu}m$. The dyeability of soybean fabric using charcoal as colorants was increased gradually with increasing concentration of charcoal dyeing solution and saturated at about 8%(o.w.b.). The optimum dyeing temperature and dyeing time were $90{\sim}105^{\circ}C$ and 60~90 minutes respectively. The overall wash fastness at dyeing concentration 2~4%(o.w.b.) and 6~10%(o.w.b.) were 4 degree and 3-4 degree respectively. The fastness to washing according to mordanting method indicated good grade result as more than 4 degree in all conditions. On the other hand, the staining of adjacent fabrics, i.e. PET, Acryl, Wool, Acetate, Nylon and Cotton was found to be of grade 4 or 4-5 in all conditions.

• Journal of Environmental Health Sciences
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• v.32 no.6
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• pp.543-555
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• 2006

During a twenty-day period in 2005, a nine-stage Andersen cascade impactor was used to determine the seasonal size distribution of atmospheric particles and its inorganic ion species sampled for 24hr in Iksan city, located southwest of the Korean peninsula. Samples were analyzed for major water-soluble ion species using Dionex-100 ion chromatograph. Average fine and coarse mass concentrations of atmospheric particles were, respectively, 31.4 and $82.6{\mu}g\;m^{-3}$ in spring and 35.8 and $73.4{\mu}g\;m^{-3}$ in fall-winter during the sampling period of 2005, while measurements of 69.8 and 9.9 were obtained in the sampling period of summer, The size distribution of particulate mass concentration during the non-Asian dust period was generally bimodal, whereas the size distribution of particulate mass concentration during the Asian dust period was unimodal due to the significant increase of coarse particles, which originated from long-range transport of soil dust particles from loess regions of the Asian continent. Among ionic species, $SO{_4}^{2-},\;NH{_4}^+,\;K^+$ were mainly distributed in fine particles due to their characteristics of emission sources and gas-to-particle conversion, while $Na^+,\;Mg^{2+}\;and\;Ca^{2+}$ were dominantly in coarse particles. However, $NO_3{^-}\;and\;Cl^-$ were distributed in both coarse particles and fine particles. Although $SO{_4}^{2-}$ was mainly distributed in fine particles, the size distributions of $SO{_4}^{2-}$ in coarse mode were significantly increased during the Asian dust events compared to those during the non-Asian dust period. $Ca^{2+}$ showed the most abundant species in the atmospheric particles during the Asian dust period. $NH{_4}^+$ was found to mainly exist as $(NH_4)_2SO_4$ in fine particles.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.2049-2054
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• 2013

Recently, magnesium hydroxide ($Mg(OH)_2$) has many applications in various field, due to its outstanding characteristics such as a nontoxic, noncorrosive and thermal stable properties. In this study, different shapes of flower and flake type magnesium hydroxide were synthesized by precipitation method at room temperature using $MgSO_4$, $MgCl_2$ and $Mg(NO_3)_2$ as magnesium sources, NaOH and $NH_3$ as alkaline sources. Influence of synthesis on the morphological characteristics, sizes and shapes of magnesium hydroxide particles, was investigated, such as different precursors and parameters. The shape of magnesium hydroxide depend on magnesium and alkali sources. Average size of flower particle had about $1{\mu}m$, and flake had about 20 ~ 50 nm. The synthesised magnesium hydroxide groups were characterized by XRD, FE-SEM, FT-IR, EDS, PSA and TG.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.122-122
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• 2017

인산-망간 화성피막의 경우 양질의 피막층을 형성하기 위하여 표면조정제를 사용하고 있으며, 화성피막 직전에 표면 조정제 처리를 하여 피막 결정의 미세, 치밀, 균일하게 하는 동시에 피막의 화성시간을 단축하고 있다. 본 연구는 표면조정제의 입자 사이즈에 따른 화성피막 입자 사이즈 변화 및 물리적인 특성 향상을 확인하였다. 하지금속 소재로는 기계구조용 탄소강재(SM45C)을 $50{\times}50{\times}3mm$로 제작하였고, 전처리 공정으로는 탈지 ${\rightarrow}$ 에칭 ${\rightarrow}$ 디스머트 후 표면조정제 입자 사이즈별로 표면조정 후, 화성피막 처리를 하였으며 각 조건에 따른 피막 층의 미세조직은 SEM을 사용하여 관찰하였고, 윤활성은 내마모시험기(Ball on disc)를 사용하여 마찰계수 측정을 통해 확인하였으며, 내식성은 5% NaCl 염수분무를 실시하여 적청 발생 면적으로 측정하였다. 표면조정제의 입자 사이즈는 4종류로 세분화하여 표면조정 후 화성피막 처리하였으며, 표면조정제의 입자 사이즈를 미세화함에 따라 화성피막의 입자 사이즈가 미세, 균일해지고 피막의 치밀도가 향상됨을 확인할 수 있었다. 표면조정제의 미분화는 소재 표면에 작고 치밀한 결정(활성점)을 만들며, 표면조정제의 입자 사이즈가 작아질수록 이러한 활성점의 크기가 미세해지고 화성피막의 입자 사이즈 또한 미세화 시키는 역할을 하는 것을 확인 할 수 있었다. 이처럼 표면 조정제의 입자 사이즈에 따른 화성피막 입자 사이즈 및 물성변화는 SEM, 내마모시험 및 내식성 시험을 통하여 확인할 수 있었다. 즉, 표면조정제의 입자 사이즈가 미세해질수록, 화성피막의 입자사이즈가 미세화되었고, 윤활성 및 내식성이 향상되는 것을 확인 할 수 있었다.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.3
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• pp.343-355
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• 2005

Cloud/fog water was collected at Daegwallyeong, a typical clean environmental area, by using an active fog sampler during the foggy period in 2002, The pH ranged from 3,7 to 6,5 with a mean of 5,0, but the pH calculated from average concentrations of $H^+$ was 4.4. $SO_4^{2-},\;NO_3^-\;and\;NH_4^+$ were predominant ions with average concentrations of 473,3, 463,3 and $576,0\;{\mu}eq/L$, respectively, This showed that cloud/fog water was slightly acidified, but the concentrations of major pollutants were as high as those for polluted area, suggesting effect from long range transported pollutants, Samples were categorized into four groups (E, W, S, N) by applying 48-h back trajectory analysis using the Hybrid Single-Particle Largrangian Integrated Trajectory (HYSPLIT) model. Concentrations of seasalt $(Na^+\;and\;Cl^-)$ were the highest for group E, indicating large input of seasalts by air masses transported from the East Sea. The concentrations of $SO_4^{2-}$ were slightly higher in group W but the difference was not significant. However, the concentrations of $NO_3^-$ were significantly higher in group W than those in other three groups, The median values of cloud/fog water pH for group N and W were below 4,5, which is significantly lower than median values in group E and group S, This suggests that the acidifying pollutants were transported from the Asia continents and Seoul metropolitan area cause acidification of the cloud/fog water in Daegwallyeong.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3444-3450
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• 2013

Three phase hollow fiber-liquid phase microextraction (HF-LPME), which is faster, simpler and uses a more environmentally friendly sample-preparation technique, was developed for the analysis of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) in human urine. For the effective simultaneous extraction/concentration of NSAIDs by three phase HF-LPME, parameters (such as extraction organic solvent, pH of donor/acceptor phase, stirring speed, salting-out effect, sample temperature, and extraction time) which influence the extraction efficiency were optimized. NSAIDs were extracted and concentrated from 4 mL of aqueous solution at pH 3 (donor phase) into dihexyl ether immobilized in the wall pores of a porous hollow fiber, and then extracted into the acceptor phase at pH 13 located in the lumen of the hollow fiber. After the extraction, 5 ${\mu}L$ of the acceptor phase was directly injected into the HPLC/UV system. Simultaneous chromatographic separation of seven NSAIDs was achieved on an Eclipse XDB-C18 (4.6 mm i.d. ${\times}$ 150 mm length, 5 ${\mu}m$ particle size) column using isocratic elution with 0.1% formic acid and methanol (30:70) at a HPLC-UV/Vis system. Under optimized conditions (extraction solvent, dihexyl ether; $pH_{donor}$, 3; $pH_{acceptor}$, 13; stirring speed, 1500 rpm; NaCl salt, 10%; sample temperature, $60^{\circ}C$; and extraction time, 45 min), enrichment factors (EF) were between 59 and 260. The limit of detection (LOD) and limit of quantitation (LOQ) in the spiked urine matrix were in the concentration range of 5-15 ng/mL and 15-45 ng/mL, respectively. The relative recovery and precision obtained were between 58 and 136% and below 15.7% RSD, respectively. The calibration curve was linear within the range of 0.015-0.96 ng/mL with the square of the correlation coefficient being more than 0.997. The established method can be used to analyse of NSAIDs of low concentration (ng/mL) in urine.

• Journal of the Korean Applied Science and Technology
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• v.31 no.1
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• pp.92-100
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• 2014

Hydrophobic magnesium hydroxide [$Mg(OH)_2$] was modified by hydrothermal method using non-ionic sorbitol surfactant with Span series. Mganesium chloride [$MgCl_2$] and sodium hydroxide [NaOH] were used for synthesis of $Mg(OH)_2$. Also non-ionic surfactant were added as a stabilizer, dispersant and surface modifier. Addition of non-ionic surfactant was favourable to obtain small sized $Mg(OH)_2$ particles with better dispersibility and hydrophobic property of $Mg(OH)_2$ particles. The obtained product were characterized by particle size analysis(PSA), scanning electron microscope(SEM), energy dispersive spectroscopy(EDS), x-ray diffraction(XRD) and fourier transform infrared spectroscopy(FT-IR). The results show that the product are prepared with this method has a well hydrophobic properties and dispersity compared with unmodified $Mg(OH)_2$ particles. The improve properties of surface modified $Mg(OH)_2$ particles were also verified by similarity synthesizing under slightly different conditions.