• Journal of Powder Materials
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• v.16 no.1
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• pp.33-36
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• 2009

In order to increase the magnetic loss for electromagnetic(EM) wave absorption, the soft magnetic $Fe_{73}Si_{16}B_7Nb_3Cu_1$(at%) alloy strip was used as the basic material in this study. The melt-spun strip was pulverized using an attrition mill, and the pulverized flake-shaped powder was crystallized at $540^{\circ}C$ for 1h to obtain the optimum grain size. The Fe-based powder was mixed with 2 wt% $BaTiO_3$, $0.3{\sim}0.6$ wt% carbon black, and polymer-based binders for the improvement of electromagnetic wave absorption properties. The mixture powders were tape-cast and dried to form the absorption sheets. After drying at $100^{\circ}C$ for 1h, the sheets of 0.5 mm in thickness were made by rolling at $60^{\circ}C$, and cut into toroidal shape to measure the absorption properties of samples. The characteristics including permittivity, permeability and power loss were measured using a Network Analyzer(N5230A). Consequently, the properties of electromagnetic wave absorber were improved with the addition of both $BaTiO_3$ and carbon black powder, which was caused by the increased dielectric loss of the additive powders.

• Journal of Environmental Science International
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• v.12 no.6
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• pp.665-676
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• 2003

To investigate the chemical characteristics of PM$\_$2.5/ in Seoul, Korea, atmospheric particulate matters were collected using a PM$\_$10/ dichotomous sampler including PM$\_$10/ and PM$\_$2.5/ inlet during the period of October 2000 to September 2001. The Inductively Coupled Plasma-Mass Spectromety (ICP-MS), ion Chromatography (IC) methods were used to determine the concentration of both metal and ionic species. A statistical analysis was performed for the heavy metals data set using a principal component analysis (PCA) to derived important factors inherent in the interactions among the variables. The mean concentrations of ambient PM$\_$2.5/ and PM/sub10/ were 24.47 and 45.27 $\mu\textrm{g}$/㎥, respectively. PM$\_$2.5/ masses also showed temporal variations both yearly and seasonally. The ratios of PM$\_$2.5/PM$\_$10/ was 0.54, which similar to the value of 0.60 in North America. Soil-related chemical components (such as Al, Ca, Fe, Si, and Mn) were abundant in PM$\_$10/, while anthropogenic components (such as As, Cd, Cr, V, Zn and Pb) were abundant in PM2s. Total water soluble ions constituted 30∼50 % of PM$\_$2.5/ mass, and sulfate, nitrate and ammonium were main components in water soluble ions. Reactive farms of NH$_4$$\^$+/were considered as NH$_4$NO$_3$ and (NH$_4$)$_2$SO$_4$ during the sampling periods. In the results of PCA for PM$\_$2.5/, we identified three principal components. Major contribution to PM$\_$2.5/ seemed to be soil, oil combustion, unidentified source. Further study, the detailed interpretation of these data will need efforts in order to identify emission sources.

• Economic and Environmental Geology
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• v.38 no.4 s.173
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• pp.481-492
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• 2005

The purpose of this study is to determine geochemical characteristics for stream sediments in the Gwangju area. We collect the stream sediments samples by wet sieving along the primary channels and dry these samples slowly in the laboratory and grind to under 200mesh using an alumina mortar fur chemical analysis. Major elements, trace and rare earth elements are determined by XRF, ICP-AES and NAA analysis methods. For geochemical characteristics on geological groups of stream sediments, we separate geologic groups which are derived from Precambrian granite gneiss area, Jurassic granite area and Cretaceous Hwasun andesite area. Contents range of major elements for stream sediments in the Gwangju area are $SiO_2\;51.89\~70.63\;wt.\%,\;Al_2O-3\;12.91\~21.95\;wt.\%,\;Fe_2O_3\;3.22\~9.89\;wt.\%,\;K_2O\;1.85\~4.49\;wt.\%,\;MgO\;0.68\~2.90\;wt.\%,\;Na_2O\;0.48\~2.34\;wt.\%,\;CaO\;0.42\~6.72\;wt.\%,\;TiO_2\;0.53\~l.32\;wt.\%,\;P_2O_5\;0.06\~0.51\;wt.\%\;and\;MnO\;0.05\~0.69\;wt.\%.$ According to the AMF diagram for stream sediments and rocks, the stream sediments are plotted on boundary of tholeiitic series and calk alkaline series, which shows that contents of $Fe_2O_3$ are higher in stream sediments than rocks. According to variation diagram of $SiO_2$ versus $(K_2O+Na_2O),$ stream sediments are plotted on subalkaline series. Contents range of trace and rare earth elements for stream sediments in the Gwangiu area are Ba$590\~2170$ppm, Be1\~2.4$ppm, Cu$13\~79$ppm, Nb$20\~34$ppm, Ni$10\~50$ppm, Pb$17\~30$ppm, Sr$70\~1025$ ppm, V$42\~135$ppm, Zr$45\~171$ppm, Li$19\~77$ppm, Co$4.3\~19.3$ppm, Cr$28\~131$ppm, Cs$3.1\~17.6$ppm, Hf$5\~27.6$ppm, Rb$388\~202$ppm, Sb$0.2\~l.2$ ppm, Sc$6.4\~17$ppm, Zn$47\~389$ppm, Pa$8.8\~68.8$ppm, Ce$62\~272$ppm, Eu$1\~2.7$ppm and Yb$0.9\~6$ppm.

• Horticultural Science & Technology
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• v.31 no.5
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• pp.544-551
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• 2013

The effect of different silicon (Si) sources and methods of application on the growth of two chrysanthemum cultivars grown in a soilless substrate was investigated. Rooted terminal cuttings of Dendranthema grandiflorum 'Lemmon Eye' and 'Pink Eye' were transplanted into pots containing a coir-based substrate. A nutrient solution containing 0 or $50mg{\cdot}L^{-1}$ Si from calcium silicate ($CaSiO_3$), potassium silicate ($K_2SiO_3$) or sodium silicate ($Na_2SiO_3$) was supplied once a day through an ebb-and-flood sub irrigation system. A foliar spray of 0 or $50mg{\cdot}L^{-1}$ Si was applied twice a week. Cultivar and application method had a significant effect on plant height. Cultivar, application method, and Si source had a significant effect on plant width. Of the three Si sources studied, $K_2SiO_3$ was found to be the best for the increasing number of flowers, followed by $CaSiO_3$ and $Na_2SiO_3$. In both the cultivars, sub irrigational supply of Si developed necrotic lesions in the older leaves at the beginning of the flowering stage as compared to the control and foliar spray of Si. Cultivar, application method, Si source, and their interactions had significant influence on leaf tissue concentrations of calcium (Ca), potassium (K), phosphorus (P), magnesium (Mg), sulfur (S), sodium (Na), boron (B), iron (Fe), and zinc (Zn). The addition of Si to the nutrient solution decreased leaf tissue concentrations of Ca, Mg, S, Na, B, Cu, Fe, and Mn in both cultivars. The greatest Si concentration in leaf tissue was found in 'Lemmon Eye' ($1420{\mu}g{\cdot}g^{-1}$) and 'Pink Eye' ($1683{\mu}g{\cdot}g^{-1}$) when $K_2SiO_3$ was applied through a sub irrigation system and by foliar spray, respectively.

• Bulletin of the Korean Chemical Society
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• v.23 no.8
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• pp.1067-1072
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• 2002

A new polystyrene-divinylbenzene resin containing 2-(2-thiazolylazo)-5-dimethylamino-phenol (TAM) functional groups has been synthesized and its sorption behavior for nineteen metal ions, including Zr(Ⅳ),Hf(Ⅳ) and U(Ⅵ) has been investigated by batch and column methods. The chelating resin showed high sorption affinity for Zr(Ⅳ) at pH 1-5 and U(Ⅵ) at pH 4. Some parameters affecting the sorption of the metal ions have been detailed. The breakthrough and overall capacities were measured under optimized conditions. The overall capacities of Zr(Ⅳ), Th(Ⅳ) and U(Ⅵ), which showed higher than the other metal ions, were 0.90,0.84 and 0.80 mmol/g, respectively. The elution order of metal ions at pH 4 was evaluated as Zr(Ⅳ) > Th(Ⅳ) > U(Ⅵ) > Cu(Ⅱ) > Hf(Ⅳ) > W(Ⅵ) > Mo(Ⅵ) > In(Ⅲ) > Sn(Ⅳ) > Cr(Ⅲ) > V(Ⅴ) > Fe(Ⅲ). Quantitative recovery of most metal ions except Zr(Ⅳ) was achieved using 2M HNO3. Desorption and recovery of Zr(Ⅳ) was successfully performed with 2 M HClO4 and 2 M HCl.

• Economic and Environmental Geology
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• v.40 no.6
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• pp.727-738
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• 2007

The present study investigation the geochemical characteristics of the stream sediments in the Unbong area was conducted to enable a understanding the natural background and a prediction the prospects of geochemical disaster as a result of that bed rocks(mylonitic granites, Kim et al., 1992). We systematically collected seventy three stream sediments samples by wet sieving along the primary channels. Major, trace and rare earth element(REE) concentrations, combined with mineralogical characteristics, were determined by XRD, XRF, ICP-AES and NAA analysis methods. Major element concentrations for the stream sediments in the Unbong area were $SiO_2\;36.94{\sim}65.39wt.%,\;Al_2O_3\;10.15{\sim}21.77wt.%,\;Fe_2O_3\;3.17{\sim}10.90wt.%,\;CaO\;0.55{\sim}5.27wt.%,\;MgO\;0.52{\sim}4.94wt.%,\;K_2O\;1.38{\sim}4.54wt.%,\;Na_2O\;0.49{\sim}3.36wt.%,\;TiO_2\;0.39{\sim}1.27wt.%,\;MnO\;0.04{\sim}0.22wt.%,\;P_2O_5\;0.08{\sim}0.54wt.%$. Trace and REE concentrations for the stream sediments were $Cu\;4.8{\sim}134ppm,\;Pb\;24.2{\sim}82.5ppm,\;Sr\;95.9{\sim}739ppm,\;V\;19.9{\sim}124ppm,\;Zr\;52.9{\sim}145ppm,\;Li\;25.2{\sim}3.3ppm,\;Co\;3.87{\sim}50.0ppm,\;Cr\;17.4{\sim}234ppm,\;Hf\;3.93{\sim}25.2ppm,\;Sc\;4.60{\sim}20.6ppm,\;Th\;3.82{\sim}36.9ppm,\;Ce\;45.7{\sim}243ppm,\;Eu\;0.89{\sim}2.69ppm,\;Yb\;1.42{\sim}5.18ppm$. According to the comparison of average major element concentrations, CaO, $Na_2O\;and\;K_2O$ contents are higher in stream sediments than in bed rocks(mylonitic granites, Kim et al., 1992) $Al_2O_3\;and\;SiO_2$ contents show good correlation both stream sediments and bed rocks(mylonitic granites, Kim et al., 1992). Yb and Eu in the stream sediments show a positive correlation with $SiO_2$. In contrast, the stream sediments display a negative correlation.

• Applied Chemistry for Engineering
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• v.8 no.1
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• pp.140-145
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• 1997

Carbon dioxide hydrogenation reaction was carried out over hybrid catalyst composed of $Cu/ZnO/ZrO_2$, and MFI zeolites such as HZSM-5, H-Ga-Silicate and H-Fe-Silicate. The hybrid catalyst composed of $Cu/ZnO/ZrO_2$, catalyst and HZSM-5 showed the highest yield and selectivity to $C_2{^+}$ hydrocarbon, which seemed to be due to the largest amount of Br nsted acid sites. Higher yield to $C_2{^+}$ hydrocarbon was obtained over HZSM-5 with lower $SiO_2/Al_2O_3$ ratio and also with longer ion exchange time, which showed larger amount of Br nsted acid sites, respectively. When a metal ion was exchanged into HZSM-5, the highest yield to $C_2{^+}$ hydrocarbon was obtained with descending order $Ga/HZSM-5{\simeq}HZSM-5>Zn/HZSM-5$, i.e., with the amount of $Br\ddot{o}nsted$ acid sites.

• Economic and Environmental Geology
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• v.42 no.3
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• pp.217-234
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• 2009

This study characterized groundwater quality and the influence of agrochemicals in a part of Ilgwang-Myeon agricultural area in Gijang-Gun, Busan Metropolitan City, using factor analyses. From the 1st, 2nd, and 3rd analyses of groundwater samples, the mean concentrations of $Ca^{2+}$, $Na^+$, $Mg^{2+}$, $K^+$, $Zn^{2+}$, $Cu^{2+}$, $Fe^{2+}$, $Al^{3+}$, $NO_3\;^-$, $Cl^-$, $SO_4\;^{2-}$, $F^-$, and $SiO_2$ were higher in the 2nd analysis than the other analyses. Pesticide carbofuran and herbicide alachlor were detected at the wells more than a half of all the wells in the 2nd analysis but not in the 4th analysis. This fact may be explained by that a higher precipitation induced higher infiltration rate of contaminants into groundwater during the 2nd survey. According to R- and Q-mode factor analyses, and chemical composition, inorganic constituents excepting $SiO_2$, $HC0_3\;^-$-, and $F^-$ may be influenced by anthropogenic sources (manures, synthetic fertilizers, and domestic wastes), seawater as well as water-mineral interaction. A typical indicator of groundwater contamination, nitrate, exceeds around 4-5 times over the Korean standard for drinking water. Additionally, the influence of seawater diminishes from the seaside to inland.

• Korean Journal of Food Science and Technology
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• v.10 no.2
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• pp.258-262
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• 1978

Proximate composition, minerals and fatty acid in dried chicory root (moisture content 7.0%) are analyzed and subsequent results are as follows: Crude protein, crude fat, crude fiber, total sugar and ash content in chicory root are 8.6%, 1.6 %, 6.9%, 58.5% and 4.2%, respectively. Mineral content of Ca, P, Fe, Mg and Si in the root are 1,560, 180, 10,600 and 180 mg%, respectively. Other minerals such as K, Na, Al, Zn, Ag, Cu and Ti are also determined. Unsaturated fatty acid content in total fat of the root is 65.4%, Particularly high in linoleic acid. Uridine-5'-diphospho-glucose, as sole nucleotide-sugar in the root, was detected.

• Korean Journal of Medicinal Crop Science
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• v.2 no.2
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• pp.162-167
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• 1994

This study was carried out to investigate the compositions of fatty acids, inorganic components and volatile organic acids from Korean valerian roots, Valeriana fauriei var. dasycarpa Hara and Valeriana officinalis var. latifolia Miq. The contents of total lipids ranged from 3.7 % to 4.5% and the major fatty acids were linoleic, linolenic and palmitic acid. Ash contents ranged from 4.3% to 6.3%. and the contents of Na, Fe, Zn and Cu showed some quantitative differences depending upon grown region or species. Fourty components were identified from acidic fraction of dichloromethane extract of V. fauriei var. dasycarpa Hara, of which the major components were 3-methyl butanoic, dimethoxy-2-propenoic. 3, 4-dimethoxy benzoic and 3-methyl pentanoic acid.