• Membrane Journal
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• v.21 no.1
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• pp.30-38
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• 2011

Composite membranes based on sulfonated poly(aryl ether) sulfone (SPAES) with different sulfated zirconia nanoparticles ($s-ZrO_2$) ratio are synthesized and investigated for the improvement of the hydration and the proton conductivity at high temperature and no humidification for fuel cell applications. X-ray diffraction technique is employed to characterize the structure and the size of $s-ZrO_2$ nanoparticles. The sulfation effect of $s-ZrO_2$ nanoparticles is verified by FT-IR analysis. The properties of the SPAES composite membranes with the various $s-ZrO_2$ ratio are evaluated by ion exchange capacity and water content. The proton conductivities of the composite membranes are estimated at room temperature with full hydration and at the various high temperature without external humidification. The composite membrane with 5 wt% $s-ZrO_2$ shows the highest proton conductivity. The proton conductivities are $0.9292\;S\;cm^{-1}$ at room temperature with full hydration and $0.0018\;S\;cm^{-1}$ at $120^{\circ}C$ without external humidification, respectively.

• Economic and Environmental Geology
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• v.34 no.2
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• pp.167-173
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• 2001

Through alkaline hydrothermal activation processes, Na-A type zeolite was synthesized as a single phase with funnel-glass waste from a television tube factory. The autoclaving was performed in a closed teflon vessel in the range of 80~95$^{\circ}$C. The silica-rich solution as a starting material was hydrothermally synthesized with quartz in IN NaOH by heating 350uC under the pressure of 1,500 atm. $NaAlO_2$ was made from NaOH and Al(OHh by heating 95$^{\circ}$C for 2-3 hours and the molar ratios of it were $Na_2O/Al_2O_3$ = 1.4 and $H_2O/Na_2O$=8. The equi-dimensional A type zeolite (1-2 11) was formed by the simple mixing of the silica-rich solution, glass waste and $NaAlO_23$ for 1-3 hours-heating at $80^{\circ}C$. The characterization of the reaction product shows Na-A as a single phase. The synthesized zeolite has cuba-dodecahedral form and $Ca^{2+}$ ion exchange capacity of the Na-A was in the range of 215-220 mequiva1entilOO g.

• Korean Journal of Soil Science and Fertilizer
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• v.18 no.4
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• pp.336-347
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• 1985

Soils and rice plants subject to smoke from the Jang-hang Smelter were samples at two depths to assess the nature and extend of Cd, Cu, Pb, and Zn contamination, particularly with respect to distance from pollution source. Soils at east site within 1km of the center of the smelter were highly contaminated with Cd, Cu, Pb, and Zn. Metal levels in the smoke-polluted area were higher in surface soil than in subsurface soil, and decreased rapidly with distance reaching nearly background levels at 5km from pollution source. A position correlation was found between contents of total and 0.1 N HCl-extractable, or 1.0N $CH_3COONH_4$- extractable heavy metals in surface soils of pollution. Contents of heavy metals in soils were positively correlated with soil organic matter and cation exchange capacity. The contents of heavy metals in brown rice collected from the paddy field around the Jang-hang Smelter were in the range of 0.23-1.33 ppm for Cd, 2.39-6.25 for Cu, 0.95-8.32 ppm for Pb and 14.60-27.31 for Zn. The contents of Cd, Cu, and Zn in rice straw were positively correlated with those in the brown rice. Negative correlation was found between the contents of Cd, Cu, Pb, and Zn in brown rice and the distance from the source.

• Membrane Journal
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• v.32 no.5
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• pp.292-303
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• 2022

An eco-friendly energy conversion device without the emission of pollutants has gained much attention due to the rapid use of fossil fuels inducing carbon dioxide emissions ever since the first industrial revolution in the 18th century. Polymer electrolyte membrane fuel cells (PEMFCs) that can produce water during the reaction without the emission of carbon dioxide are promising devices for automotive and residential applications. As a key component of PEMFCs, polymer electrolyte membranes (PEMs) need to have high proton conductivity and physicochemical stability during the operation. Currently, perfluorinated sulfonic acid-based PEMs (PFSA-PEMs) have been commercialized and utilized in PEMFC systems. Although the PFSA-PEMs are found to meet these criteria, there is an ongoing need to improve these further, to be useful in practical PEMFC operation. In addition, the well-known drawbacks of PFSA-PEMs including low glass transition temperature and high gas crossover need to be improved. Therefore, this review focused on recent trends in the development of high-performance PFSA-PEMs in three different ways. First, control of the side chain of PFSA copolymers can effectively improve the proton conductivity and thermal stability by increasing the ion exchange capacity and polymer crystallinity. Second, the development of composite-type PFSA-PEMs is an effective way to improve proton conductivity and physical stability by incorporating organic/inorganic additives. Finally, the incorporation of porous substrates is also a promising way to develop a thin pore-filling membrane showing low membrane resistance and outstanding durability.

• Applied Biological Chemistry
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• v.15 no.1
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• pp.49-57
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• 1972

Varietal difference in root distribution and other root characteristics were investigated under fold and water culture condition. The results were as follows: 1. IR667 showed funnel type of root distribution in soil profit while Jinheung had barrel type, and each type appearance was more distinguishable with fertilizer application. 2. Root weight per tiller was smaller in IR667 than in Jinheung and IR667 had more root in 0 to 5cm of soil depth but Jinheung had more in 5 to l0cm depth. 3. Horizontal distribution of root was dencer near to stem base without fertilizer than with fertilizer in both IR667 and Jinheung indicating structural construction for intensive nutrient uptake. Between varieties this 'dence to stem base' trend accompaning 'dence to wide spacing side' was greater in IR667 without fertilizer and these were quite true with fertilizer in Jinheung. 4. The decreasing rates of root and ear weight by fertilizer application were greater in IR667 than in Jinheung. This and other characteristics indicated that the root of IR667 is likely to be panicle-number type comparing with Jinheung. 5. The root of IR667 had lower oxidizing power of ${\alpha}-naphthylamine$ than that of Jinheung indicating weaker resistance to reductive soil but cation exchange capacity of water-cultured root was higher in IR667 suggesting stronger nutrient uptake. 6. The content of phosphorus and especially potassium in root were higher with fertilizer but lower without fertilizer in IR667 than in Jinheung indicating that IR667 is more sensitive to root environment. 7. The contents of N, K and CEC were increasing toward root tip while P content was decreasing. The root from surface soil had higher N and K content than that from subsoil. The contents of N,P,K, and CEC of root at harvesting stage were about 1.0%, 0.1%, 0.5% and 15me/100g at dry weight base, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.11
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• pp.1007-1018
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• 2009

Hydrocyclone is widely used in industry, because of its simplicity in design, high capacity, low maintenance and operational cost. The separation action of a hydrocyclone treating particulate slurry is a consequence of the swirling flow that produces a centrifugal force on the fluid and suspended particles. In spite of hydrocyclone have many advantage, the application for treatment of urban stormwater case study were rare. We conducted a laboratory scale study on treatable potential of micro particles using hydrocyclone filter (HCF) that was a combined modified hydrocyclone with perlite filter cartridge. Since it was not easy to use actual storm water in the scaled-down hydraulic model investigations, it was necessary to reproduce ranges of particles sizes with synthetic materials. The synthesized storm runoff was made with water and addition of particles; ion exchange resin, road sediment, commercial area manhole sediment, and silica gel particles. Experimental studies have been carried out about the particle separation performance of HCF-open system and HCF-closed system. The principal structural differences of these HCFs are underflow zone structure and vortex finder. HCF was made of acryl resin with 120 mm of diameter hydrocyclone and 250 mm of diameter filter chamber and overall height of 800 mm. To determine the removal efficiency for various influent concentrations of suspended solids (SS) and chemical oxygen demand (COD), tests were performed with different operational conditions. The operated maximum of surface loading rate was about 700 $m^3/m^2$/day for HCF-open system, and 1,200 $m^3/m^2$/day for HCF-closed system. It was found that particle removal efficiency for the HCF-closed system is better than the HCF-open system under same surface loading rate. Results showed that SS removal efficiency with the HCF-closed system improved by about 8~20% compared with HCF-open system. The average removal efficiency difference for HCF-closed system between measurement and CFD particle tracking simulation was about 4%.

• Korean Journal of Environment and Ecology
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• v.30 no.4
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• pp.762-770
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• 2016

This study intended to investigate environmental factors including soil and vegetation in order to understand the environmental and ecological characteristics of the Korean endemic species, Syringa fauriei. Syringa fauriei is mainly distributed along the valley and riverside of the Gangwondo and its population is located at an elevation of 121~520m. Consequent to a vegetation survey within natural populations, a total of 320 taxa were identified from 20 quadrates in 4 natural populations. The Syringa fauriei population was classified into Securinega suffruticosa dominant population, Acer pseudosieboldianum dominant population, Amorpha fruticosa dominant population and Sorbaria sorbifolia var. stellipila dominant population. According to the physical and chemical soil analysis, Syringa fauriei habitats contained 1.98~2.81% of organic matter and 0.13~0.20 mg/kg of total nitrogen. The concentrations of cation exchange capacities $K^+$, $Ca^{2+}$, and $Mg^{2+}$ were $0.10{\sim}0.33cmol^+/kg$, $3.44{\sim}20.53cmol^+/kg$, and $0.34{\sim}0.95cmol^+/kg$, respectively. Positive ion substitution capacity was $8.08{\sim}13.68cmol^+/kg$. The pH was 6.28~7.74. The importance value of Deutzia glabrata, Fraxinus rhynchophylla, Alangium platanifolium var. trilobum, Syringa fauriei, Juglans mandshurica, and Salix koreensis in the Syringa fauriei population were 86.99%, 43.97%, 23.01%,18.52, 18.40%, and 11.56%, respectively. Correlation analysis between the vegetation of Syringa fauriei populations and its environmental factors using DCCA revealed that the altitude above sea level and $Mg^{2+}$ were the most influential factors, while dominant populations of Securinega suffruticosa and Acer pseudosieboldianum were spread across areas with high percentages of pH, CEC, and $Mg^{2+}$. Acer pseudosieboldianum population was dispersed in areas with higher $K^+$ compared to Securinega suffruticosa population. The dominant population of Amorpha fruticosa was found to live in places with high altitudes above sea level and with high rates of available phosphate, $K^+$, and rock-exposure.

• Journal of the Mineralogical Society of Korea
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• v.21 no.4
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• pp.341-347
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• 2008

The feasibility of commercializing the hydrothermal synthesis of Na-A type zeolite from siliceous mudstone has been conducted using a 50-liter bench-scale autoclave and the application of the zeolite as an environmental remediation agent. Siliceous mudstone, which is widely distributed around the Pohang area, was adopted as a precursor. The siliceous mudstone is favorable for the synthesis of zeolite because it contains 70.7% $SiO_2$ and 10.0% $Al_2O_3$, which are major ingredient of zeolite formation. The synthesis of zeolite was carried out under the following conditions that had been obtained from the previous laboratory-scale tests: 10hr reaction time, $80^{\circ}C$ reaction temperature, $Na_2O/SiO_2$ ratio = 0.6, $SiO_2/Al_2O_3$ ratio = 2.0 and $H_2O/Na_2O$ ratio= 98.6. The crystallinity and morphology of the zeolite formed were similar to those obtained from the laboratory-scale tests. The recovery and cation exchange ion capacity were 95% and 215 cmol/kg, respectively, which are slightly higher than those obtained in laboratory scale tests. To examine the feasibility of the zeolite as an environmental remediation agent, experiments for heavy metal adsorption to zeolite were conducted. Its removal efficiencies of heavy metals in simulated waste solutions decreased in the following sequences: Pb > Cd > Cu = Zn > Mn. In a solution of 1500 mg/L total impurity metals, the removal efficiencies for these impurity metals were near completion (> 99%) except for Mn whose efficiency was 98%. Therefore, the synthetic Na-A type zeolite was proven to be a strong absorbent effective for removing heavy metals.