• Korean Journal of Soil Science and Fertilizer
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• v.41 no.3
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• pp.177-183
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• 2008

Sodium is known to reduce a plant growth and yields. However, the relationships between physiological response of seedling and salinity stress caused by growing media are not well understood yet. We conducted experiments to investigate change of some parameters including Na, EC, moisture content in media under different air temperature ($15^{\circ}C$, $25^{\circ}C$), and the response of fruit-vegetables such as cucumber, oriental melon on saline conditions originated from horticultural substrate. Volumetric moisture content of media at $15^{\circ}C$ was 70%, but at $25^{\circ}C$ was decreased by 45% within 22 hrs, showing below optimal matric potential, approximately. During reaction time, the increase of Na concentration was significantly greater in saline substrate than in control. The decrease rate of Na concentration according to supplying irrigation water was higher in saline substrate than in control. $CO_2$ assimilation rate and transpiration rate of Korea melon grown in low temperature were decreased with a Na/cation ratio in hydroponic solution. Water saturation deficit was also increased significantly at $15^{\circ}C$ as compare to $25^{\circ}C$. Saline stress during nursery stage induced a reduction of seedling quality, growth and cucumber yield. The results suggest that the relationship between uncontrolled Na uptake of seedling from saline substrate and meteological condition is responsible for saline stress.

• Membrane Journal
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• v.11 no.3
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• pp.133-139
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• 2001

The hydorgen ions in PVA/SSA membranes were substituted with monovalent metal ions, $Li^{+}$, $Na^{+}$, $K^{+}$, divalent metal ion forms, $Mg^{2+}$, $Ca^{2+}$, $Ba^{2+}$, trivalent metal ion forms, $Al^{+}$. The effect of exchange with metal ions was investigated through the swelling measurement and pervaporative experiments for water-ethanol and water-methanol mixtures at various operating conditions. In addition, ESCA analysis was carried out to study the substitution of the metal ions in membranes. The swelling ratio decerased in the sequence of $Li^{+}$, $Na^{+}$, $K^{+}$ and this might be due to the 'salting-out` effect while the swelling ratios for divalnet and trivalent ion-substituted membranes were affected by the combined effect of salting-out, electrostatic crosslinking and extent of metal ion substitution. For the pervaporation performance, PVA/SSA-$H^{+}$membrane showed the lowest flux and highest separation factor for all aqueous ethanol solutions. The typical results of the flux, 59 g/$m^{2}$hr and the separation factor, 44 were obtained at $50^{\circ}C$ for 90% ethanol aqueous mixture. For water-methanol solutions, the PVA/SSA membranes substituted with monovalent PVA/SSA membranes substituted with divalent and tribalent metal ions, both `salting-out` and electrostatic effects affected the pervaporative results.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.9
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• pp.1476-1485
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• 2004

Of solvent-extracts prepared from the 90 kinds of Korean traditional tea and rice gruel plants, cold-water extract from peels of Citrus unshiu (CUI-0) showed the most potent intestinal immune system modulating activity through Peyer’s patch whereas other extracts did not have the activity except for cold-water extracts of Laminaria japonica, Polygonatum japonicum, Poncirus trifoliata, and hot-water extracts of Gardenia jasminoides, Lycium chinense having intermediate activity. CUI-0 was further fractionated into MeOH-soluble fraction (CUI-1), MeOH insoluble and EtOH-soluble fraction (CUI-2), and crude polysaccharide fraction (CUI-3). Among these fractions, CUI-3 showed the most potent stimulating activity for the proliferation of bone marrow cells mediated by Peyer’s patch cells, and contained arabinose, galacturonic acid, galactose, glucose, glucuronic acid and rhamnose (molar ratio; 1.00:0.53:0.45:0.28:0.28:0.19) as the major sugars, and a small quantity of protein (9.4%). In treatments of CUI-3 with pronase and periodate (NaIO₄), the intestinal immune system modulating activity of CUI-3 was significantly reduced, and the activity of CUI-3 was affected by periodate oxidation particularly. The potently active carbohydrate-rich fraction, CUI-3IIb-3-2 was further purified by anion-exchange chromatography on DEAE-Sepharose FF, Sepharose CL-6B and Sephacryl S-200. CUI-3IIb-3-2 was eluted as a single peak on HPLC and its molecular weight was estimated to be 18,000 Da. CUI-3IIb-3-2 was consisted mainly of arabinose, galactose, rhamnose, galacturonic acid and glucuronic acid (molar ratio;1.00:0.54:0.28:1.45:0.63) in addition to a small amount of proteins (3.2%). In addition, CUI-3IIb-3-2 showed the activity only through Peyer’s patch cells, but this fraction did not directly stimulate proliferation of bone marrow cells. It may be concluded that intestinal immune system modulating activity of peels from C. unshiu is caused by pectic polysaccharides having a polygalacturonan moiety with neutral sugars such as arabinose and galactose.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.1
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• pp.1-6
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• 1984

Soils in Cheju Island, derived mostly from volcanic ashes, were collected for chemical analysis to determine the effect of land utilization pattern on soil chemical characteristics. The coastal area has long been used for intensive farming and some of the mid-mountain region were recently reclaimed for agricultural crop production. The cation exchange capacity and the organic matter in the soils increased in the order of coastal area < mid-mountain belt < upper mountain area, while pH, base saturation, available phosphorus and exchangeable bases decreased with the elevation. Generally, the organic matter, the cation exchange capacity and the exchangeable bases of the Cheju soils were found to be considerably higher than the Korean mainland soils. However, the base saturation and the available phosphorus were far below the mainland average. The ratio of monovalent basic cations to total exchangeable bases showed the highest in the soils of the mountain belts and the lowest in the coastal area soils. These data suggest that a higher soil pH in the coastal area as compared to the mountainous slopes has resulted not from the sea water but from continuous application of alkaline fertilizers and times.

• Korean Journal of Materials Research
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• v.22 no.4
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• pp.207-210
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• 2012

The preparation of $Sm_2O_3$ doped $CeO_2$ in Igepal CO-520/cyclohexane reverse micelle solutions has been studied. In the present work, we synthesized nanosized $Sm_2O_3$ doped $CeO_2$ powders by reverse micelle process using aqueous ammonia as the precipitant; hydroxide precursor was obtained from nitrate solutions dispersed in the nanosized aqueous domains of a micro emulsion consisting of cyclohexane as the oil phase, and poly (xoyethylene) nonylphenylether (Igepal CO-520) as the non-ionic surfactant. The synthesized and calcined powders were characterized by Thermogravimetry-differential thermal analysis (TGA-DTA), X-ray diffraction analysis (XRD), and Transmission electron microscopy (TEM). The crystallite size was found to increase with increase in water to surfactant (R) molar ratio. Average particle size and distribution of the synthesized $Sm_2O_3$ doped $CeO_2$ were below 10 nm and narrow, respectively. TG-DTA analysis shows that phase of $Sm_2O_3$ doped $CeO_2$ nanoparticles changed from monoclinic to tetragonal at approximately $560^{\circ}C$. The phase of the synthesized $Sm_2O_3$ doped $CeO_2$ with heating to $600^{\circ}C$ for 30 min was tetragonal $CeO_2$. This study revealed that the particle formation process in reverse micelles is based on a two step model. The rapid first step is the complete reduction of the metal to the zero valence state. The second step is growth, via reagent exchanges between micelles through the inter-micellar exchange.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.11
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• pp.689-695
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• 2016

The performance of proton exchange membrane fuel cells (PEMFC) is strongly related to the water flow and accumulation in the gas diffusion layer (GDL) and catalyst layer. Understanding the behavior of fluid from the characteristics of the media is crucial for the improvement of the performance and design of the GDL. In this paper, a numerical method is proposed to calculate the design parameters of the GDL, i.e., permeability, tortuosity, and effective diffusivity. The fluid flow in a channel filled with randomly packed hard spheres is simulated to validate the method. The flow simulation was performed by lattice Boltzmann method with bounce back condition for the solid volume fraction in the porous media, with different values of porosities. Permeability, which affects the flow, was calculated from the average pressure drop and the velocity in the porous media. Tortuosity, calculated by the ratio the average path length of the randomly injected massless particles to the thickness of the porous media, and the resultant effective diffusivity were in good agreement with the theoretical model. The suggested method can be used to calculate the parameters of real GDL accurately without any modification.

• Korean Journal of Medicinal Crop Science
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• v.18 no.4
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• pp.273-279
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• 2010

The study result survey platycodon cultivation regions of Jinju(2), Sacheon(4), Hapcheon(3), Haman(3), and Sancheong(3) of Gyongnam regarding chemical properties of soil, inorganic nitrogen phosphorus by type of composition is as follows: pH and EC value were highest where platycodon cultivated for under 3 years in soils. Content of O.M equal to or less than 25 mg $kg^{-1}$, the average value for platycodoncultivation in korea. Content of exchangeable calcium in soils were 12, 14 $cmol^+kg^{-1}$ in Hapcheon and Haman regions where platycodon was cultivated for two years which is 2~3 time higher level compared with the average upland soil of korea. Water solution boron confirmed approximated level of 3.0 mg $kg^{-1}$ in all survey regions, and the finding is about five times higher than average upland soil of korea which is 0.5 mg $kg^{-1}$. In the case of nitrogen, a significant difference was found depending on cultivation regions and continuous culture. Content of nitrogen in soils were difference according to cultivation area and continuous culture. The composition ratio according to the type of inorganic phosphorus showed the highest in order of Al-P > Ca-P > Fe-P > Saloid-P in all survey regions except for Hapcheon (five, seven years cultivated soils). The correlation showed high significance between available phosphate and inorganic phosphorus.

• The Korean Journal of Mycology
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• v.12 no.1
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• pp.35-43
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• 1984

To produce and characterize antineoplastic constituents in the submerged cultured­mycelia of Laccaria laccata, the mycelia were extracted with distilled water. Purification of the extract was carried out by acetone precipitation, by ion exchange chromatography using DEAE­Sephadex A-50, CM-Sephadex C-25 resins, and by gel filtration chromatography on Sephadex G-200. Each fraction obtained during the purification was examined for antineoplastic activity against sarcoma 180 in ICR mice. As the purification proceeded, the antineoplastic activity was markedly increased. The highly purified Fraction E showed 75% tumor inhibition ratio at a dose of 10mg/kg/day and contained 81% polysaccharide and 4% protein. The antitumor component of Fraction E stimulated an accumulation of peritoneal exudate cells including peritoneal macrophages, and is named laccaran.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.243.1-243.1
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• 2011

We demonstrate a facile and robust layer-by-layer (LbL) assembly method for the fabrication of nonvolatile resistive switching memory (NRSM) devices based on superparamagnetic nanocomposite multilayers, which allows the highly enhanced magnetic and resistive switching memory properties as well as the dense and homogeneous adsorption of nanoparticles, via nucleophilic substitution reaction (NSR) in nonpolar solvent. Superparamagnetic iron oxide nanoparticles (MP) of about size 12 nm (or 7 nm) synthesized with oleic acid (OA) in nonpolar solvent could be converted into 2-bromo-2-methylpropionic acid (BMPA)-stabilized iron oxide nanoparticles (BMPA-MP) by stabilizer exchange without change of solvent polarity. In addition, bromo groups of BMPA-MP could be connected with highly branched amine groups of poly (amidoamine) dendrimer (PAMA) in ethanol by NSR of between bromo and amine groups. Based on these results, nanocomposite multilayers using LbL assembly could be fabricated in nonpolar solvent by NSR of between BMPA-MP and PAMA without any additional phase transfer of MP for conventional LbL assembly. These resulting superparamagnetic multilayers displayed highly improved magnetic and resistive switching memory properties in comparison with those of multilayers based on water-dispersible MP. Furthermore, NRSM devices, which were fabricated by LbL assembly method under atmospheric conditions, exhibited the outstanding performances such as long-term stability, fast switching speed and high ON/OFF ratio comparable to that of conventional inorganic NRSM devices produced by vacuum deposition.

• Polymer(Korea)
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• v.25 no.6
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• pp.789-795
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• 2001

In order to recover nickel ion from waste water containing heavy metals, the PAN fibrous ion-exchanger with primary, secondary amine groups and carboxyl group was synthesized by acid and base hydrolysis. The hydrolysis yield of PAN fiber in acid solution was higher than base solution. The swelling ratio and ion-exchange capacity of PAN fiber which was synthesized in 1N $H_2SO_4$ solution at $80^{\circ}C$ for 7 hrs appeared 71.2% and 1.95 meq/g respectively. We investigated that the adsorption of nickel ion was approached 1.44 meq/g at 50 min and the maximum adsorption capacity of ion-exchanger was 2.48 meq/g. We confirmed that the $Ni^{+2}$ adsorption ability of the synthesized PAN fibrous ion-exchanger in this study is excellent.