• Membrane Journal
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• v.28 no.4
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• pp.221-232
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• 2018

The silica containing carbon ($C-SiO_2$) membranes were fabricated using poly(imide siloxane)(Si-PI) and polyvinylpyrrolidone (PVP) blended polymer. The characteristics of porous carbon structures prepared by the pyrolysis of polymer blends were related with the micro-phase separation behaviors of the two polymers. The glass transition temperatures ($T_g$) of the mixed polymer blends of Si-PI and PVP were observed with a single $T_g$ using differential scanning calorimetry. Furthermore, the nitrogen adsorption isotherms of the $C-SiO_2$ membranes were investigated to define the characteristics of porous carbon structures. The $C-SiO_2$ membranes derived from Si-PI/PVP showed the type IV isotherm and possessed the hysteresis loop, which was associated with the mesoporous carbon structures. For the molecular sieving probe, the $C-SiO_2$ membranes were prepared with the ratio of Si-PI/PVP and the pyrolysis conditions, such as the pyrolysis temperature and the isothermal times. Consequently, the $C-SiO_2$ membranes prepared by the pyrolysis of Si-PI/PVP at $550^{\circ}C$ with the isothermal time of 120 min showed the $O_2$ permeability of 820 Barrer ($1{\times}10^{-10}cm^3(STP)cm/cm^2{\cdot}s{\cdot}cmHg$) and $O_2/N_2$ selectivity of 14.

• Korean Journal of Organic Agriculture
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• v.20 no.2
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• pp.231-241
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• 2012

Farming using natural salts for supply of nutrients to crops is increasing recently. It is necessary to evaluate the salt accumulation in soil and the effects on crop growth by treatment of natural salt. This study was conducted at the organic cultivation fields which garlics were planted. The treatments were no natural salts (control) and plots applied 100~600 $kg\;ha^{-1}$ with natural salts. Soil samples were taken from the 0 to 25 cm depth at 12 and 107 day (harvest time) after natural salts application. The results showed that electrical conductivity (EC), exchangeable Na (Exch.$-Na^+$) and Cl- were increased by application of natural salts. But, pH and exchangeable cations ($K^+$, $Ca^{2+}$ and $Mg^{2+}$) had not significantly differences among treatments. In 300 $kg\;ha^{-1}$ plots of natural salt, the level of EC, Exch.$-Na^+$ and $Cl^-$ in top soil (0-5 cm) was were increased more 0.3, 3.7, and 12.7 times than control plot, respectively. EC, Exch.$-Na^+$, and $Cl^-$ were highest in the top 5 cm of soil and decreased with depth at 12 days after natural salts application, but were decreased in the plower layer (0-15cm) at the harvest time because they were leached with natural rain. An increasing the application level of natural salt resulted in increasing of sodium adsorption ratio, exchangeable sodium percentage, and percentage of soil dispersion. The concentration of nutrient uptake such as total nitrogen (T-N), chloride (Cl) in garlic had significant difference between control and plots applied with natural salts The content of T-N of garlic in plots with natural salt application was lower than control plot, but Cl is higher than control plot.

• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.304-309
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• 1999

Aluminum-pillared clay was prepared by the intercalation of Al-hydroxy oligomer into domestic bentonite. The solid products are characterized by XRD, nitrogen adsorption/desorption, EDX, and SEM. The solid products show relatively high specific surface areas in the range of $104{\sim}228m^2/g$, and their specific surface area, micropore surface area, and micropore volume increase with increasing the mole ratio of OH/Al. From the results of pore size distribution calculated by BJH equation, it was found that aluminum-pillared clay also contains much mesopore near $40{\AA}$. These results indicate that Al-hydroxy oligomer was intercalated into bentonite, and aluminum oxide was pillared among the layers of bentonite, and micropore and mesopore was finally developed into layers. As OH/Al mole ratio increases, the thermal stability of aluminum-pillared clay increases. This result can be explained by the fact that the density of layers is increased due to the formation of aluminum pillars.

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.574-581
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• 2008

The optimum regeneration conditions for the regeneration of three way spent catalysts (TWCs), which were taken from automobiles with different driving conditions, were investigated to evaluate the suitability as alternative catalysts for removing VOCs. The spent catalysts were washed with five different acids ($HNO_3$, $H_2SO_4$, $C_2H_2O_4$, $C_6H_8O_7$, and $H_3PO_4$) to remove contaminants and examine the optimum conditions for recovering the catalytic activity. The physicochemical properties of spent and its regenerated TWCs were evaluated by using nitrogen adsorption-desorption isotherms, XRD, and ICP. The relative atomic ratios of contaminants and platinum group metals (PGMs) of the spent TWCs were greatly dependent on the placed positions. The main contaminants formed were lubricant oil additives and metallic components. Also, the regeneration treatment increased the PGMs ratio, BET surface area, and average pore diameter of TWCs. The catalytic activity results indicated that the spent TWCs have the possibility for removing VOCs. Moreover, the employed acid treatments greatly enhanced the catalytic activity of the spent TWCs. Especially, nitric and oxalic acids provided the most improvement in the catalytic behavior. The catalytic activities of the regenerated TWCs were significantly influenced by the containing platinum ratios rather than the removal ratios of contaminants and the changes in the structural properties offered by the acid treatments.

• Korean Chemical Engineering Research
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• v.43 no.1
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• pp.9-15
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• 2005

In order to know the electrochemical decomposition characteristics of ammonia to nitrogen, this work has studied several experimental variables on the electrolytic ammonia decomposition. The effects of pH and chloride ion at $IrO_2$, $RuO_2$, and Pt anodes on the electrolytic decomposition of ammonia were compared, and the existence of membrane equipped in the cell and the changes of the current density, the initial ammonia concentration and so on were investigated on the decomposition. The performances of the electrode were totally in order of $RuO_2{\approx}IrO_2>Pt$ in the both of acid and alkali conditions, and the ammonia decomposition was the highest at a current density of $80mA/cm^2$, over which it decreased, because the adsorption of ammonia on the electrode surface was hindered due to the evolution of oxygen. The ammonia decomposition increased with the concentration of chloride ion in the solution. However, the increase became much dull over 10 g/l of chloride ion. The $RuO_2$ electrode among the tested electrodes generated the most OH radicals which could oxidized the ammonium ion at pH 7.

• Journal of Plant Biology
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• v.24 no.1
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• pp.31-45
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• 1981

The purpose of this study aimed to study effects of fire on vegetation and soil properties after the first growing season in Mt. Chiak. 1. With the basis of importance value of species in each stand, status of species was assessed for three categories; Increaser species, Decreaser species, and Neutral species. 2. Biomass was 2.2 times higher on burned area than unburned. This indicates that biomass was remarkably increased after fire. 3. To evaluate similarity, coefficients of similarity among communities were obtained, and correlation coefficients were also estimated. These indices showed that burned and unburned community were markedly different.. $B_1$-stand and $B_1$-stand appeared most similar to each other among stands. 4. Species diversity was greater in burned than unburned stands. 5. Soil pH value and organic matter content in burned area were significantly higher than those in unburned area. However, soil water content was lower in burned area. There was no effect of burning on soil pH value and water content at 15~20 cm depth of soil. 6. All chemical compositions except sodium were much higher in soil surface. The decreases in sodium levels at surface were probably resulted from the rapid leaching due to the increased solubility and decreased capacity for adsorption of sodium in comparison with potassium or calcium. Among chemical compositions of soil amount of nitrogen showed least difference between the burneb and unburned surfaces soil.

• Clean Technology
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• v.22 no.2
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• pp.114-121
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• 2016

In this studies, SCR reaction activity and SO₂ durability enhancement study on manufacturing conditions of the V/TiO₂ catalyst was carried out for the removal of nitrogen oxides generated in the combustion furnace. The catalysts are characterized by XPS, Raman, H₂-TPR and SO₂-TPD. When the vanadium was contained of 2 wt%, it showed excellent SO₂ durability and catalytic activity. and When the tungsten is added as a promotor, the enhancement of reducing ability at a low temperature and reduction of SO₂ adsorption capacity improved the reaction activity and SO₂ durability. V/W/TiO₂ are prepared by the lower pH of vanadium solution, vanadium was highly dispersed on the surface and inhibited the formation of crystalline V₂O₅. in addition, it was confirmed that this catalyst can be used as excellent resistance to high concentration of CO in the combustion furnace.

• Journal of the Korean GEO-environmental Society
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• v.8 no.4
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• pp.19-25
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• 2007

Process analysis with ASM3 (Activated Sludge Model3) was performed to offer basic data for the optimization of aerated biofilter (ABF) process design and operation. This study was focused on the simulation of the nitrification reaction in ABF which was a part of the advanced nutrient treatment process using bio-adsorption. The ABF process has been developed for the removal of suspended solids and nitrification reaction in sewage. A GPS-X (General Purpose Simualtor-X) was used for the sensitivity analysis and operation assessment. Sensitivity of ASM3 parameters on ABF was analysed and 4 major parameters ($Y_A$, $k_{sto}$, ${\mu}_A$, $K_{A,HN}$) were determined by dynamic simulation using 70 days data from pilot plant operation. The optimized values were 0.14 for $Y_A$, 3.5/d for $k_{sto}$, 2.7/d for ${\mu}_A$ and 1.1 mg/L for $K_{A,HN}$, respectively. Simulation with optimized parameter values were conducted and TN, $NH_4{^+}-N$ and $NO_3{^-}-N$ concentrations were estimated and compared with measured data at the range of 10 min to 4 hrs of hydraulic retention time (HRT). The simulated results showed that optimized parameter values could represent the characteristics of ABF process. Especially, the ABF showed relatively high nitrification rate (60%) under very short HRT of 10 min. As a consequence, the ABF was thought to be successfully used in the site which having high variation of influent loading rate.

• Journal of Sensor Science and Technology
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• v.7 no.4
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• pp.254-262
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• 1998

Multilayer Langmuir-Blodgett (LB) films coated on quartz crystal microbalance (QCM) of octa-substituted metallophhtalocyanines ($MPc(OEH)_8$, M = Cu, Co, and Sn) and dihydrogen phthalocyanines ($H_2Pc(OEH)_8$) were used to quantify $NO_2$ concentrations. They were exposed to various concentrations of $NO_2$ in dry $N_2$. Among the four phthalocyanines we tested, the metal-free $H_2Pc(OEH)_8$ was observed to be most sensitive to $NO_2$. However, its LB film showed a partially irreversible behavior, that is part of the frequency change due to $NO_2$ adsorption could not be recovered even after purging with pure $N_2$ gas for an extended period. Examining the spectra of NMR and FTIR revealed fact that the irreversible portion of frequency change was due to ether groups in the linkage between side chains and the Pc unit. In order to remove the effect of such initial deactivation, on $NO_2$ quantification experiment, a freshly fabricated LB film was treated at a high concentration of $NO_2$ so that the ether sites were saturated. A pretreated LB film showed a reproducible performance for repeated uses. The $CuPc(OEH)_8$ LB film showed a satisfactory sensing performance down to as low as 4 ppm. For the $H_2Pc(OEH)_8$ LB film, the lower detection limit was found to be 35ppb of $NO_2$. In order to make the experimental condition more realistic, the carrier gas, dry nitrogen, was replaced by air. It was observed that the presence of oxygen, a weak electron acceptor, reduced the sensitivity and thus increased the sensing limit to hundreds of ppb. Results of experiments with moisture added showed that the interference of moisture was quite severe.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.5
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• pp.361-368
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• 2000

This study was carried out to investigate the influence of artificial zeolite on the change of temperature, gas emission, water content and chemical properties during the composting process with the mixture of animal feces, broken bark and extruded rice hull. Artificial zeolite was added 0, 0.5, 1, 3 and 5% volume of the raw composting material, and proceeded 1.2m every day with mobile stacking escalator. Temperature was increased, and water content was decreased in the composting pile by addition of artificial zeolite. This caused to accelerate decomposition of organic matter during composting. $NH_3$ was emitted the highest at 6th day after stacking, then decreased gradually. And addition of artificial zeolite caused to decrease greatly in $NH_3$ emission from composting pile. As result of this, content of nitrogen in the compost was increased by addition of artificial zeolite. Emission of $CH_4$ was the highest at early stacking stage, and that was decreased drastically at 8th day. Emission of $CH_4$ was also decreased greatly by addition of artificial zeolite at 5th days after stacking. It may be resulted from adsorption of $CH_4$ into the molecular sieve structure of artificial zeolite and low water content by high temperature fermentation.