• Bulletin of the Korean Chemical Society
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• v.5 no.1
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• pp.44-49
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• 1984

The ionic association constant (K) of N-methyl pyridinium iodide (NMPI) ion in several ethanol-water mixtures were determined by the combination of UV spectroscopy and conductance measurements using the Shedlovsky function as a correction factor. The measurement of electrical conductance and UV absorption were performed in 95, 90, 80 and 60 volume percentages of ethanol in the solvent mixture at 15, 25, 35 and 45 $({\pm}0.1)^{\circ}C$. The ion size parameter $(r_A+_D-)$ and the dipole moment $({\mu}_A+_D-)$ of NMPI ion were obtained from he linear plots of ln K vs. (1/D) and (D-1)/(2D+1), respectively. These ${\mu}_A+_D-$ values were in good agreement with the values of transition moment calculated from the equation, ${\mu}_{nm}=6.5168{\times}10^{-2}{\times}({\varepsilon}_{max}{\frac{\bar{\nu}_{\frac{1}{2}}}{\bar{\nu}_{max}})^{\frac{1}{2}}$ (Debye) which we have derived. The thermodynamic parameters indicate (1) that the water dipoles have an ordered rearrangement around the dipolar NMPI ions rather than the configuration existing in bulk free waters; and (2) that the equilibrium state between NMPI ion and its component ions are controlled by entropy.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.3
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• pp.287-301
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• 2015

This study was conducted to investigate size distribution characteristics of water-soluble ionic components in the airborne particulate matter (PM) collected from an urban area in Busan using a MOUDI cascade impactor from March to October 2010. The inorganic constituents in the fine particles (${\leq}1.8{\mu}m$) predominantly consisted of sulfate, nitrate, ammonium, and potassium. Sulfate and ammonium concentrations showed a high correlation and similar equivalent concentrations in the fine modes including $0.18{\sim}0.32{\mu}m$, $0.32{\sim}0.56{\mu}m$, and $0.56{\sim}1.0{\mu}m$. This indicates that the main chemical component in the fine particles would be forms of ammonium sulfate such as $(NH_4)_3H(SO_4)_2$, $(NH_4)_2SO_4$, and $(NH_4)HSO_4$. Back trajectory analysis showed that relatively higher concentrations of ammonium, nitrate, and sulfate in the fine mode, compared to the coarse mode, are caused both by domestic sources and long-range transports originated from China continent. High concentration episodes of PM both in the fine mode and the coarse mode were attributed both by anthropogenic sources, such as ship emissions and traffic emissions, and by natural sources such as seawater (sea salt), respectively.

• Asian Journal of Atmospheric Environment
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• v.11 no.2
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• pp.79-95
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• 2017

A number of field studies have provided evidence that biomass burning is one of the major global sources of atmospheric particles. In this study, we have collected $PM_{2.5}$ emitted from biomass burning combusted at open burning and laboratory chamber situations. The open burning experiment was conducted with the cooperation of 9 farmers in Chiba Prefecture, Japan, while the chamber experiment was designed to evaluate the characteristics of chemical components among 14 different plant species. The analyzed categories were $PM_{2.5}$ mass concentration, organic carbon (OC), elemental carbon (EC), ionic components ($Na^+$, ${NH_4}^+$, $Ca^{2+}$, $Mg^{2+}$, $K^+$, $Cl^-$, ${NO_3}^-$ and ${SO_4}^{2-}$), water-soluble organic carbon (WSOC), water-insoluble inorganic carbon (WIOC), char-EC and soot-EC. OC was the dominant chemical component, accounting for the major fraction of primary $PM_{2.5}$ derived from biomass burning, followed by EC. Ionic components contributed a small portion of $PM_{2.5}$, as well as that of $K^+$. In some cases, $K^+$ is used as biomass burning tracer; however, the observations obtained in this study suggest that $K^+$ may not always be suitable as a tracer for biomass burning emissions. Also, the results of all the samples tested indicate relatively low values of char-EC compared to soot-EC. From our results, careful consideration should be given to the usage of $K^+$ and char-EC as indicators of biomass burning. The calculated ratios of WSOC/OC and WIOC/OC were 55.7% and 44.3% on average for all samples, which showed no large difference between them. The organic materials to OC ratio, which is often used for chemical mass closure model, was roughly estimated by two independent methods, resulting in a factor of 1.7 for biomass burning emissions.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.481-485
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• 2014

The applicability of the dipping, ultrasonic-assisted, heating methods to the extraction of useful components from Zostera marina was investigated. For the increase of the extraction yield of caffeic acid and rosmarinic acid from Zostera marina, ionic liquids and DES were used as additives in the extraction solvent. The optimum extraction conditions were found: dipping extraction, methanol as extraction solvent, 0.005 g of freeze-dried material powder, 5 mL methanol, 30 min and 0.5 g of DES-3 ($Et_4NCl$ and phenol) as additive. As a result, 0.19 mg/g of caffeic acid and 8.48 mg/g of rosmarinic acid were obtained. This method is simple and sensitive, and has been applied successfully to determine the component of caffeic acid and rosmarinic acid in Zostera marina and these results indicate that DES were used as additives is more suitable than traditional extraction for the extraction of useful components from Zostera marina.

• Journal of the Korean Society for Heat Treatment
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• v.23 no.3
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• pp.150-155
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• 2010

Generally, plasma nitriding process has composed with a nitriding layer within glow discharge region occurred by energy exchange. The dissociations of nitrogen molecules are very difficult to make neutral atoms or ionic nitrogen species via glow discharge area. However, the captured electrons in which a double-folded screen with same potential cathode can stimulate and come out some single atoms or activated ionic species. It was showed an important thing that is called "hat is a dominant component in this nitriding process?" in plasma nitriding process and it can take an effective species for without compound layer. During a plasma nitriding process, it was able to estimate with analyzing and identification by optical emission spectroscopy (OES) study. And then we can make comparative studies on the nitrogen transfer with plasma nitriding and ATONA process using plasma diagnosis and metallurgical observation. From these observations, we can understand role of active species of nitrogen, like N, $N^+$, ${N_2}^+$, ${N_2}^*$ and $NH_x$-radical, in bulk plasma of each process. And the same time, during DC plasma nitriding and other processes, the species of FeN atom or any ionic nitride species were not detected by OES analyzing.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.1
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• pp.119-129
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• 2005

The ambient TSP data measured at Seoul, Incheon. Taean, Daegu, Busan in Korea were used to explain the chemical composition and general features of Asian Dust (AD) observed in Korea. 9 episodes out of 19 were sampled from 2000 through May 2002, and measurements were conducted covering ionic and metal components with mass concentration. The results showed that daily averaged mass concentration (TSP) during the AD episodes was 458 $\mu\textrm{g}$/㎥, and ionic and metal concentrations were 27.93 $\mu\textrm{g}$/㎥ and 71.7 $\mu\textrm{g}$/㎥, respectively, accounting for 6.1 % and 15.5% of the total aerosol mass. TSP concentrations during episodes were varied from 120 to 1742 $\mu\textrm{g}$/㎥ according to the impact of Asian Dusts and had a tendency of showing higher values at sites in the west side of Korea, which can be explained by the effect of diffusion and deposition. In this study, ionic components like Ca (NO$_3$)$_2$, CaSO$_4$, NaNO$_3$, Na$_2$SO$_4$ were prominent types in secondary aerosol during AD periods and also indicated that V, Co as well as soil elements such as Ca, Fe, Mg, Mn, K correlated well with Al, while Cu, Cd, Pb, Zn didn't agree well with it. In addition, enrichment factors (EFs) for each metal component were obtained to provide simple information about source contribution of Asian Dust, and the results were compared with those from other AD studies. In this study, the results showed that aerosol properties in Korea during the Asian Dust were considerably different from those of general atmospheric condition and specially varied from case to case rather than site to site, which implies that there are certain variations in the soil of source region, pathways of air mass, and meteorological condition. For the enhanced study, those factors should be combined with the features of Asian Dust resolved from this study.

• Journal of Environmental Health Sciences
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• v.20 no.4
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• pp.1-9
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• 1994

In order to investigate the regional level of air pollutants at Kangwha island situated on the western coast in Korea, the suspended particulate matter samples were collected by using the low volume air sampler on ten interval from March 1992 to February 1993 and the mass concentration of suspended particulate matter (SPM) and the chemical composition of water-soluble major ionic components in SPM samples were measured. During the sampling period, the average concentration of SPM under diameter 10 $\mu$m was found to be 48 $\mu$g/m$^3$ (+ 12). The seasonal concentration of SPM was showed in order of spring>fall>winter>summer. It was considered that higher concentration on spring than other season was affected by the long-range transport of Yellow sand particulate from China continent and lower concentration on summer by the washout and rainout effect of large rainfall. The content of water-soluble component in SPM samples was founded to be about 31% (14.69 $\mu$g/m$^3$) and 65% was unknown or unanalyzed. The content of cationic component showed in order of NH$_4^+$ (44.6%)>Na$^+$ (21.2%)>K$^+$ (14.7%)>Ca$^{2+}$ (13.6%)>Mg$^{2+}$ (5.9 %) and the content of anionic component SO$_4^{2-}$ (62.5%)>NO$_3^-$ (22.3%)>Cl$^-$ (15.2%), respectively. This fact indicates that ammonium and sulfate ion of water-soluble component in SPM sample were dominant in this region. From the chemical composition of water-soluble component, the most of Na$^+$, Mg$^{2+}$ and Cl$^-$ were originated from seawater source but K$^+$, Ca$^{2+}$ and SO$_4^{2-}$ were originated from other non-marine source. The contribution of seasalt to the composition of precipitation was 23%.

• Elastomers and Composites
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• v.52 no.4
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• pp.272-279
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• 2017

The heterocoagulation of latex is a simple and useful method to fabricate various polymer nanocomposites in which a precise control of the colloid stability is essential. In this work, a multi-layered graphenes (MLGs)/poly(styrene-co-butyl acrylate) (P(S-co-BA)) nanocomposite having an excellent dispersion of MLGs was prepared via the sudden heating heterocoagulation process. The P(S-co-BA) component was obtained by emulsion polymerization. This process can effectively shorten the process and particles growth steps. The colloid stability of these dispersions was controlled by factors such as ionic charge, temperature, and reaction times. The influence of these factors on heterocoagulation was evaluated and the properties of the nanocomposites were investigated. The conductivity of the MLGs/P(S-co-BA) nanocomposites increased from -11.53 to -5.70 S/cm for an increase in MLG content from 0.01 to 5 wt%. Moreover, percolation threshold was observed in the case of 0.01 wt% MLGs.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.2
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• pp.17-22
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• 2003

Electropolishing is the electrolytic removal of metal in a highly ionic solution by means of an electrical potential and current. It is normally used to remove a very thin layer of material on the surface of a metal part or component. Electropolishing is able to enhance the material properties of a workpiece and to change its physical dimensions. Also, It is suitable for the polishing of both complex shapes and hardened materials, which are difficult to machine mechanically. therefore, the aim of the present study is to investigate the characteristic of Electropolishing A12024 in terms of current density, polishing time and electrode gap, etc.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.4
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• pp.317-325
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• 2002

An air pollution monitoring station has been operated at Tokchok Island since April 1999 to characterize the background atmosphere in the vicinity of the Yellow Sea. In this study, eight chemical species in PM$_{2.5}$ and three gaseous species were analyzed. A total of 53 samples were collected for the analysis of PM$_{2.5}$ and gaseous species from April, 1999 to April, 2001. The overall mean mass concentration of PM$_{2.5}$ was 20.8 $\mu\textrm{g}$/㎥ and the eight soluble ionic species accounted for about 46.8% of PM$_{2.5}$ mass. Approximately 80% of samples appeared to experience the chloride loss effect. Air pollutant sources of PM$_{2.5}$ measured at Tokchok Island were qualitatively identified by the principal component analysis. It was found that five principal components are secondary aerosol, soil, incineration, phase change of nitrate, and ocean.and ocean.