• Polymer(Korea)
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• v.25 no.6
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• pp.765-773
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• 2001

In In order to remove harmful trace elements such as $Co^{2+}$, $Ni^{2+}$ , $Cr_2O_7\;^{2-}$ from water, we synthesized AN-co-(MMA/IA) according to various mole ratio of monomers and spun by wet-spinning. And multi-functional PAN ion exchangers were prepared by hydrolysis. We observed structure, degree of functionalization, ion exchange capacity, distribution coefficient and mechanical properties for ion exchanger. Anion exchange capacity decreased in 4.5 ~ 4.2 meq/g with increasing of IA content and cation exchange capacity increased in 1.8 ~ 2.2 meq/g. Tensile strength of the ion exchanger increased up to 0.008 mol% IA content and appeared maximum value by 216$kg/cm^2$Distribution coefficient for AN-co-(MMA/IA) ion exchanger appeared maximum value for Co(II), Ni(II) in pH 5-6 range and for Cr(III) in pH 3-4 range. And the adsorption capacity was in the order of Cr(III) > Co(II) > Ni(II) for multicomponent in continuous process.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.11 no.3
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• pp.50-61
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• 2008

Environmental factors and phragmites growth properties at various habitats in Eulsukdo ecological park were investigated to understand major factors affecting phragmites distribution in constructed wetlands. Although phragmites is very important species in wetland ecosystem, it should be controlled to prevent excessive expansion within the restricted park area. The results showed that phragmites dominant sites have the highest LAI among other emerged plants habitats and could adversely affect for waders habitats. Phragmites were also found at the areas with wide ranges of water-depth than other plants, and showed phragmites could be favored for occupying the newly constructed wetlands like Eulsukdo ecological park. The results showed difference in soil redox potential between phragmites dominant and non-dominant sites. Because soil redox potential is affected by wetland hydrology like flooding duration, control of wetland hydrology should be considered for creation and management of constructed wetlands. The results also showed that differences in soil cation exchange capacity, soil salinity, soil organic matter content and site inclination between phragmites dominant and non-dominant sites as well as brackish and freshwater areas. Those abiotic factors can be important considerations for the sustainable wetland management especially for the phragmitest managements in the ecological park.

• Korean Journal of Environment and Ecology
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• v.29 no.2
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• pp.250-262
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• 2015

This study aims to investigate the characteristics of the vegetation structure in the sectin stretching between the Jilmoi wetlands and the Donghae Observatory and to set the criteria for the basic data for a management plan including restoration afterwards. 12 plots($10m{\times}40m$, $20m{\times}20m$) were set up to analyse the vegetation structure. The analysis of the classification by TWINSPAN and ordination by DCA, importance percentage and property, distribution of diameter of breast height, growth increments of major woody species, species diversity and the physicochemical properties of soil were all analyzed. Vegetation classes were divided into 3 communities, which are community I (Pinus densiflora community), community II (Quercus mongolica community) and community III (Quercus mongolica-Tilia amurensis community). The P. densiflora community declined when competing with Q. mongolica and Fraxinus rhynchophylla and Q. mongolica competed with T. amurensis on an understory layer in Q. mongolica community. Q. mongolica competed with T. amurensis on both canopy and understory layers in Q. mongolica-T. amurensis community. P. densiflora declined and it was assumed to succeed to F. rhynchophylla or T. amurensis through Q. mongolica based on the importance percentage and distribution of the diameter of the breast height of small and middle sized trees. The age of P. densiflora was between 47 to 51 years old and Q. mongolica was 61years old. T. amurensis was 61 years old and the growth of Q. mongolica slowed a little. As the result of Shannon's index of species diversity, community I ranged from 0.9578 to 1.1862, community II ranged from 0.7904 to 1.2286 and community III ranged from 0.8701 to 1.0323. The contents of organic matter and cation were low compared to uncultivated mountain soil and it were analysed to be inappropriate for tree growth.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.148-151
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• 2003

The spin density of ${\beta}-MnO_2$ structure was theoretically investigated by $DV-X_{\alpha}$ (the discrete variation $X{\alpha}$) method, which is a sort of the first principle molecular orbital method using Hatre-Fock-Slater approximation. The used cluster model was $[Mn_{14}O_{56}]^{-52}$. The ${\beta}-MnO_2$ is a paramagnetic oxide semiconductor material having the energy band gap of 0.18 eV and an 3 loan-pair electrons in the 3d orbital of an cation. This material exhibits spin-only magnetism and has the magnetic ordering temperature of 94 K. Below this temperature its magnetism appears as antiferromagnetism. The calculations of electronic state showed that if the initial spin condition of input parameters changed, the magnetic state changed from paramagnetic to antiferromagnetic. When d orbital of all Mn atoms in cluster had same initial spin state as only up spin, paramagnetic spin density distribution appeared by the calculation. On the other way, d orbital had alternately changed spin state along special direction the resulted spin distribution showed antiferromagnetism.

• Biomolecules & Therapeutics
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• v.27 no.3
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• pp.290-301
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• 2019

Paeonol has neuroprotective function, which could be useful for improving central nervous system disorder. The purpose of this study was to characterize the functional mechanism involved in brain transport of paeonol through blood-brain barrier (BBB). Brain transport of paeonol was characterized by internal carotid artery perfusion (ICAP), carotid artery single injection technique (brain uptake index, BUI) and intravenous (IV) injection technique in vivo. The transport mechanism of paeonol was examined using conditionally immortalized rat brain capillary endothelial cell line (TR-BBB) as an in vitro model of BBB. Brain volume of distribution (VD) of [$^3H$]paeonol in rat brain was about 6-fold higher than that of [$^{14}C$]sucrose, the vascular space marker of BBB. The uptake of [$^3H$]paeonol was concentration-dependent. Brain volume of distribution of paeonol and BUI as in vivo and inhibition of analog as in vitro studies presented significant reduction effect in the presence of unlabeled lipophilic compounds such as paeonol, imperatorin, diphenhydramine, pyrilamine, tramadol and ALC during the uptake of [$^3H$]paeonol. In addition, the uptake significantly decreased and increased at the acidic and alkaline pH in both extracellular and intracellular study, respectively. In the presence of metabolic inhibitor, the uptake reduced significantly but not affected by sodium free or membrane potential disruption. Similarly, paeonol uptake was not affected on OCTN2 or rPMAT siRNA transfection BBB cells. Interestingly. Paeonol is actively transported from the blood to brain across the BBB by a carrier mediated transporter system.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.3
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• pp.347-357
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• 2018

The applicability of room temperature ionic liquids (RTILs), 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([$C_nmim$] [$Tf_2N$]), was investigated for the extraction of Am(III) and Eu(III) from nitric acid using n-octyl(phenyl)-N,N-diisobutyl carbamoylmethyl phosphine oxide (CMPO) and tri-n-butylphosphate (TBP) as extractants. The distribution ratios of Am(III) and Eu(III) in CMPO-TBP/[$C_nmim$][$Tf_2N$] were measured as a function of various parameters such as the concentrations of nitric acid, CMPO, and TBP. The results were compared with those obtained in CMPO-TBP/n-dodecane (n-DD). With comparable concentrations of the extractants, the distribution ratios obtained with RTILs were much higher than those obtained with n-DD. It was observed that the extraction efficiency was less for Eu(III) than for Am(III). The extraction of Am(III) and Eu(III) decreased with increases in the feed acidity for all three RTILs. The results suggest that the extraction of Am(III) and Eu(III) by CMPO in RTILs from nitric acid proceeds through the cation-exchange mechanism. The distribution ratios of Am(III) and Eu(III) increased with increases in the concentration of CMPO for all three RTILs. A linear regression analysis of the extraction data resulted in a straight line with a slope of about 3, suggesting the involvement of 3 molecules of CMPO during the extraction process.

• The Korean Journal of Ecology
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• v.17 no.3
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• pp.277-286
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• 1994

The contents of major elements were determined in current-year and previous-year needles and fine roots of pitch pine (Pinus yzgida) at 33 sites in Seoul and its vicinity. Contrary to Ca and Al in needles, N, P, Mg and K contents in current-year needles were higher than those in previous-year needles. The N, P, K and Al contents in current-year needles in Seoul were not significantly different from those in rural areas. In contrast, Ca and Mg contents in needles in Seoul were significantly lower than those in suburbs and rural areas. The N /Ca and N /Mg ratios in needles in urban Seoul were higher than those in rural areas. Mg contents in fine roots in soil of 0-5 cm depth increased along with distance from the center of Seoul, while Al contents in fine root in soil of 5-10 cm depth decreased along with distance from the center of Seoul. Al contents in fine roots in soil layer in Seoul and suburbs were higher than those in rural areas. Al contents in fine roots in litter layer were 1 /3 - 1 /2 times lower than those in soil layer for all areas. A1 content in fine roots in deep soil was higher than that in top soil. Therefore growth decline of pitch pine in Seoul and suburbs was thought to be caused by Ca and Mg deficiency in plant tissues and Al toxicity to fine roots. Abnormal vertical distribution of fine roots of pitch pine in Seoul and its vicinity were interpreted as the result of growth reduction of fine roots by Al toxicity in deep layer of acid soil.

• Journal of the Korean Chemical Society
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• v.42 no.1
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• pp.122-134
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• 1998

In this review, we describe the electrochemical properties of spinel-type lithium manganese oxides $(Li_xMn_2O_4)$ and their failure modes encountered in 4 V lithium rechargable cells. The long-term cyclability (reversibility) of spinel electrodes is determined partly by the purity, size and distribution of spinel particles, and also by the microstructure of electrode plates. A proper selection of electrolytes is another important task in cyclability enhancements. In the spinel preparation, impurity formation and cation mixing should be minimized. The carbon content in composite cathodes should also be minimized to the extent where the cell polarization does not bring about adverse effects on cell performances. The binder content should be optimized on the basis of dispersion of component materials and mechanical strength of the plates. Cathodic capacity losses arising from solvent oxidation and spinel dissolution can be mitigated by using electrolytes composed of carbonates and/or fluorine-containing lithium salts. The carbon additives may be selected after a trade-off between the cell polarization in composite cathodes and the solvent oxidation on carbon surface.

• Korean Journal of Agricultural Science
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• v.20 no.2
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• pp.145-152
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• 1993

Vegetational data obtained from 15 quadrats of Mt. Daeam area were analysed by applying two multivariate methods : two-way indicator species analysis(TWINSPAN) for classification and detrended canonical correspondence analysis(DCCA) for ordination. The dominant tree species were Quercus mongolica, Acer pseudo-sieboldianum, Betula costata, and Acer mono in descending order. The pH ranges were 5.0 to 5.5 in the 15 sites near bog and 5.3 to 5.4 in the 3 sites within bog. The forest communities in Mt. Daeam were classified into Quercus mongolica-Acer mono, Quercus mongolica-Prunus sargentii, Quercus mongolica-Abies nephrolepis-Acer tschonoskii var, rubripes, and Quercus mongolica-Abies nephrolepis-Betula costata according to the TWINSPAN. The relationships between the distribution of dominant species of forest vegetation and soil in the forest of Mt. Daeam were investigated by analyzing soil nutrition gradient. Quercus mongolica-Prunus sargentii forests were distributed in the good sites in nutrition levels of total nitrogen, cation exchange capacity, $Mg^{+{+}}$ and $Ca^{+{+}}$ but Quercus mongolica-Abies nephrolepis-Betula costata forests in the poor sites in the nutrition levels.

• Applied Chemistry for Engineering
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• v.28 no.3
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• pp.355-359
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• 2017

Zeolite X with Si/Al molar ratio = 1.08~1.20 was produced using a hydrothermal synthesis method. Ion-exchanged zeolite X samples were then prepared by using metal nitrate solutions containing $Mg^{2+}$ or $Cu^{2+}$. For all zeolite X samples, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS) were used to identify the change in crystal structure. The analysis of ammonia adsorption capability of zeolite X samples was conducted through the ammonia temperature-programmed desorption ($NH_3$-TPD) method. From XRD results, the prepared zeolite X samples maintained the Faujasite (FAU) structure regardless of cation contents in zeolite X, but the crystallinity of zeolite X containing $Mg^{2+}$ and $Cu^{2+}$ cations decreased. The distribution of cation contents in zeolite X was identified via EDS analysis. $NH_3$-TPD analysis showed that the $NH_3$ adsorption capacity of $Mg^{2+}$- and $Cu^{2+}$-zeolite X were 1.76 mmol/g and 2.35 mmol/g, respectively while the $Na^+$-zeolite X was 3.52 mmol/g ($NH_3/catalyst$). $Na^+$-zeolite X can thus be utilized as an adsorbent for the removal of ammonia in future.