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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Korean Society for Atmospheric Environment
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Korean Society for Atmospheric Environment
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Volume 18, Issue 6 - Dec 2002
Volume 18, Issue 5 - Oct 2002
Volume 18, Issue 4 - Aug 2002
Volume 18, Issue 3 - Jun 2002
Volume 18, Issue 2 - Apr 2002
Volume 18, Issue 1 - Feb 2002
Volume 8, Issue 6 - 00 2002
Volume 8, Issue 5 - 00 2002
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Synthesis of Novel 3,3'-dimethyl-2,2'-bipyridyl Derivatives Having Nematic Liquid-crystalline and Photominescent Properties
이지한 ; 정노희 ;
Journal of Korean Society for Atmospheric Environment, volume 8, issue 2, 2002, Pages 103~103
Liquid-crystalline 3,3'-dimethyl-2,2'-bipyridyl derivatives with long 4-(alkoxyphenyl)ethynyl groups at the 5,5'-prositions were synthesized by palladium-catalyzed cross-coupling reaction, and the obtained compounds exhibited only the nematic phased as the liquid-crystalline phase. And liquid-crystalline 3,3'-dimethyl-2,2'-bipyridyl derivatives with long 4-(alkoxyphenyl)ethynyl groups showed quantum yields higher than 45% in photoluminescence.
Relationship between Structure and Performance of Polymance of Polyacrylates Used as Chelator in Detergents
Xia, Young Mei ; 조헌영 ; Fang, Yun ; Liou, Xiao Ya ; 서정목 ;
Journal of Korean Society for Atmospheric Environment, volume 8, issue 2, 2002, Pages 108~108
The effects of molecular weight and compositions of polyacrylates, i.e. sodium homopolyacrylates and modified polyacrylates on their tolerance to calcium ion (CaV), dispersancy and flocculence were investigated. The optimum formulations of phosphate-free detergent powder containing the polymers as substitute of phosphate in detergent were obtained by orthogonal test. By increasing the molecular weight of homopolyacrylate in testing range, their CaV are enhanced dramatically and the dispersancy are decreased but still are better than that of sodium tripolyphosphate (STPP). The modified polyacrylates were copolymerized with maleic anhydride (MA), methyl acrylate(AM) and acrylic acid (AA) with different compositions. The composition of copolymer affects its CaV slightly. By increasing the molecular weight in testing range, their CaV are enhanced moderately and the dispersancy of copolymer are slightly decreased. The flocculence of the polymer is enhanced by increasing the molecular weight, and is not related to type of the polymer but CaV of the polymer.
Role of Dilute Polymer Solution in Penicillin G Extraction by Emulsion Liquid Membranes
이상철 ; 여선미 ;
Journal of Korean Society for Atmospheric Environment, volume 8, issue 2, 2002, Pages 114~114
Penicillin G was extracted using a secondary amine Amberlite LA-2, as a carrier by emulsion liquid membranes (ELMs) in a batch system, where a dilute polymer solution was used as the organic membrane phase, which followed non-Newtonian behavior. The effect of the concentrations of the polymer and surfactant in the membrane phase on the extraction of penicillin G was investigated. To analyze the ELM system, the emulsion swelling and viscosities of the membrane and emulsion phases were also measured before of after the extraction. With the addition of a small quantity of polymer to the membrane phase, the emulsion swelling was reduced without any decrease in the final degree of extraction. Accordingly, the applicability of ELM processes with use of a dilute polymer solution to penicillin G extraction would appear to be promising.
Development of Pellet-type Adsorbents for Removal of Heavy Metal Ions from Aqueous Solutions Using Red Mud
한상원 ; 김동근 ; 황인국 ; 배재험 ;
Journal of Korean Society for Atmospheric Environment, volume 8, issue 2, 2002, Pages 120~120
Pellet-type adsorbents were made from red mud, generated as a by-product during the production of aluminum hydroxide from bauxite ore. Adsorption experiments of heavy metal ions (
) in aqueous solutions by the pellet-type red mud adsorbents were studied under various experimental conditions. It was found that pellet-type red mud adsorbents made from a mixture of 58.7 wt% red mud, 25.2 wt% kaolin, 11.7wt% sodium silicate solution, 2.9wt% fly ash, and 1.5wt% magnesium chloride at 600℃ exhibited the highest removal efficiency of the geavy metal ions. The removal efficiency of
after 24 h of operation was more than 95%. The pellet-type red mud adsorbents in the present study were found to follow a Langmuir equilibrium isotherm. A continuous adsorption experiment showed that the pellet-type red mud adsorbents were effective in removing
A study on the Displacement Current of Fatty Acid and Polyamic Acid Mixture
박근호 ; 송주영 ;
Journal of Korean Society for Atmospheric Environment, volume 8, issue 2, 2002, Pages 126~126
Mixed monolayers composed of fatty acid and polyamic acid containing azobenzene on a water surface were investigated by means of the Maxwell displacement current(MDC) measurement method. The MDCs were generated across mixed monolayers due to the compression of fatty acid and polyamic acid. The surface pressure and MDCs generated were also investigated in connection with monolayer compression and expansion cycles. It was found that MDCs were generated over the entire range of molecular area, and the maximum of MDCs appeared at the molecular area just before the initial rise of surface pressure in compression.
Flocculation Characteristics of Copolymer of Acrylamide with Quaternary Ammonium Cationic Monomer (Running) Flocculation by Cationic polyacrylamide
조미숙 ; 송봉근 ; 윤기준 ;
Journal of Korean Society for Atmospheric Environment, volume 8, issue 2, 2002, Pages 131~131
Copolymers of acrylamide (AM) and acryloyloxyethyl dimethylbenzyl ammonium chloride (AODBAC) synthesized by dispersion polymerization in aqueous media were evaluated as flocculents and retention aids in papermaking. The flocculation of a model CaCO₃ suspension was monitored by measuring the floc size using a particle size analyzer. The effects of the molecular weight, copolymer, and shear on flocculation were investigated. The cationic copolymers exhibited an improved flocculation behavior compared to the homopolymer, polyacrylamide, plus the floc size increased with an increase in the molecular weight. The copolymers showed also a better shear resistance than the homopolymer. The flocculation was more sensitive to the molecular weight of the copolymers than to the copolymer composition or charge density of the copolymers. It was also shown that the copolymers prepared in a dispersed state could be applied as efficient retention aids in papermaking.
Preparation and Swelling Behavior of Biodegradable Superabsorbent Gels Based on Polyaspartic Acid
김지흥 ; 이주희 ; 윤성욱 ;
Journal of Korean Society for Atmospheric Environment, volume 8, issue 2, 2002, Pages 138~138
High molecular weight polysuccinimide (PSI), as the precursor polymer for water-soluble polyaspartic acid, was prepared by the thermal polycondensation of L-aspartic acid. Superabsorbent gels were then prepared based on the crosslinking reaction of polysuccinimide with several oligomeric diamines containing an ethyleneimine structural unit in N,N-dimethylformamide and the subsequent hydrolysis of the resulting polymers in an aqueous suspension. The swelling behavior of the crosslinked gels and the effect of the dissolved ions were also investigated.
Catalytic Degradation of Mixture of Polyethylene and Polystyrene
이승엽 ; 윤직현 ; 박대원 ;
Journal of Korean Society for Atmospheric Environment, volume 8, issue 2, 2002, Pages 143~143
The catalytic degradation of a mixture of polyethylene (PE) and polystyrene (PS) was investigated in a semi-batch reactor. The influence of the nature of the cracking catalyst and the reaction temperature was also studied. The main degradation product was liquid oils with gasoline range carbon number distribution. Natural clinoptilolite zeolite (HNZ) exhibited an equivalent catalytic performance to silica-alumina (SA). The HZSM-5 catalyst produced the highest amount of gaseous products. An increased in the degradation temperature resulted in a decrease in ethylbenzene and propylbenzene, but an increase in styrene. A Thermogravimetric analysis revealed an interaction between PE and PS in the catalytic degradation.
Photocatalytic Decomposition of Bromate over Titanium Dioxides Prepared Using Sol-Gel Method
홍성수 ; 이만식 ; 김준호 ; 안병현 ; 임권택 ; 이건대 ;
Journal of Korean Society for Atmospheric Environment, volume 8, issue 2, 2002, Pages 150~150
The photocatalytic decomposition of bromate ions was carried out over various titanium dioxides prepared using the sol-gel method from titanium isopropoxide with different R ratios (H₂O/titanium isopropoxide) and calcinations temperatures. All the titanium dioxides were characterized by XRD, a BET surface area analyzer, and UV-DRS. The effect of the reaction conditions, such as the initial concevtration of the reactants, catalyst weight, and initial pH of the solution on the photocatalytic activity was also studied. The titanium dioxide prepared with a R ratio of 75 and calcined at 700℃ exhibited the highest activity in the photocatalytic decomposition of bromate. The photocatalytic decomposition of bromate showed a pseudo-1 st order reaction, plus the decomposition rate increased with a decrease in the initial bromate concentration and exhibited a maximum value with a pH 7 solution. Accordingly, it would appear that the decomposition of bromate occurred due to the photogenerated electrons of titania and was unaffected by the oxidant.
Photocatalytic Degradation of Gas-Phase Methanol and Toluene Using Thin-Film
Photocatalyst I. Influence of Water Vapor, Molecular Oxygen and Temperature
김상범 ; 장현태 ; 홍성창 ;
Journal of Korean Society for Atmospheric Environment, volume 8, issue 2, 2002, Pages 156~156
In the present work, photocatalytic degradation of volatile organic compounds (VOCs) including gas-phase methanol and toluene over illuminated TiO₂ was closely examined in a batch photo-reactor as a function of water vapor, molecular oxygen, and temperature. Water vapor enhanced the photocatalytic degradation rate of toluene, while there was an optimum water vapor concentration in decomposing methanol. In pure nitrogen atmosphere, it showed lower photocatalytic degradation rate than in air and pure oxygen. Thus, the effect of molecular oxygen on photocatalytic degradation of methanol and toluene was significant. As for the influence of reaction temperature, it was found that photocatalytic degradation was more effective at the room temperature than at an elevated temperature for both compounds.
Photocatalytic Degradation of Gas-Phase Methanol and Toluene Using Thin-Film
Photocatalyst Ⅱ. Kinetic Study for the Effect of Initial Concentration and Photon Flux
김상범 ; 차왕석 ; 홍성창 ;
Journal of Korean Society for Atmospheric Environment, volume 8, issue 2, 2002, Pages 162~162
This paper examined the kinetics of photocatalytic degradation of volatile organic compounds (VOCs) including gaseous methanol and toluene. Variable parameters were initial concentration of methanol and toluene and photon flux of ultra-violet (UV) light. Abatch photo-reactor was specifically designed for this work. The photocatalytic degradation rate increased with increasing the initial concentration of methanol and toluene, but maintained almost constant beyond a certain concentration. It matched well with the Langmuir-Hinshelwood (L-H) kinetic model. As for the effect of photon flux, it was found that photocatalytic degradation reaction occurs in two regimes with respect to photon flux.
Electrical Impedance Tomography Technique for the Visualization of the Phase Distribution in an Annular Tube
김민찬 ; 김경연 ; 김신 ; 이헌주 ; 이윤준 ;
Journal of Korean Society for Atmospheric Environment, volume 8, issue 2, 2002, Pages 168~168
The experimental and algorithmic works are conducted to obtain the phase distribution in the two-phase flow using the electrical impedance tomography (EIT) in an annular geometry. The finite element method (FEM) is employed in the forward problem and a regularized Newton-Raphson iterative method is used in the inverse problem. The reconstructed images based on our numerical algorithm and experimental works identify the position of dispersed phase. The quality of reconstructed image seems to be dependent on the number and position of the targets. It seems that our works can be used to visualize the phase distribution in an annular tube.
Performance Analysis on the Size Classification of Fly Ash Using a Guide-Vane Type Cyclone Classifier
Journal of Korean Society for Atmospheric Environment, volume 8, issue 2, 2002, Pages 173~173
For the the size classification of fly ash, the performance of a special type of cyclone classifier equipped with guide vane was investigated. Due to the wide variations in the size of fly ash, it is commonly practiced to use more than techniques to measure the entire size range. Since the size definitions vary on the basis of the measurement methods, it is necessary to convert on type of data to the other. Using a recently developed technique for inter-conversion of sizes, the separation efficiency of the cyclone classifier with guide vane was analyzed by adopting the Tromp curve. The results showed that the cut size of cyclone classifier was about 56 μm and the amount of bypass was 16%, which indicated an inefficient separation. This could be attributed to the heterogeneous nature of the fly ash particles, which limited sharp separation of the particles in the range of 10~50 μm. It was also found that the removal efficiency of unburned carbon from the raw fly ash was about 74.5% with a yield of 51%.
Characteristics of Ozone Generation using Superposing (SPCP + DC Corona) and Coil Discharge Reactor
강현준 ; 우인성 ; 한성만 ; 황명환 ; 강안수 ;
Journal of Korean Society for Atmospheric Environment, volume 8, issue 2, 2002, Pages 180~180
In this paper, characteristics of ozone generation using a coil and SPCP+DA corona reactor were investigated. We have developed a hybrid reactor which employs a corona discharge unit together with a surface discharge unit. Experimental results suggest that the efficiency of ozone production is improved. The ozone concentration versus discharge power increased to the maximum point so to decrease to greatly reduced point. In the SPCP reactor, the maximum ozone concentration was 2900 ppm at 7.6 kV and 5 kHz, 2800 ppm at 5.9kV and 10 kHz and 3100ppm at 5.5kHz. For the superposing discharge, frequency was the most important factor. When coil discharge was applied, the 10 kHzexcitation shows the largest ozone concentration and the maximum ozone concentration was 1600 ppm at 3 W, 5 kHz, 2600 ppm at 2.7 W, 10 kHz and 2100 ppm at 2.8 W, 15 kHz.
Numerical Analysis of Convection-Driven Melting and Solidification in a Rectangular Enclosure
김신 ; 김민찬 ; 이봉수 ;
Journal of Korean Society for Atmospheric Environment, volume 8, issue 2, 2002, Pages 185~185
The role of natural convection during phase change is of importance in crystal growth, materials processing, purification of materials, and others. A fixed-grid finite volume numerical approach is developed to simulate physical details of convection-dominated melting and solidification problems. This approach adopts the enthalpy-porosity method associated with new algorithms devised to track the phase front efficiently. A comparative analysis with transformed- and fixed-grid approaches is performed to demonstrate the predictability of the presented model. Results of melting and solidification experiments are used to assess and evaluate the performance of the model.
The Computational Simulation of Skin-Permeation of Vitamins C and F
정휘동 ; 이성철 ;
Journal of Korean Society for Atmospheric Environment, volume 8, issue 2, 2002, Pages 191~191
Anadvanced two-dimensional bilayer skin bioconversion model is developed to assay the skin-permeation of vitamins C and E. The numerical method of line (NMOL) is exploited to solve a set of governing equations based on species mass balance. The penetration profiles of vitamins C and E in the stratum corneum decrease quickly along the depth of the stratum couneum. But the penetration profile of vitamin C is more uniform than that of vitamin E along the depth of the viable skin. This result shows that a large amount of vitamin E is bio-converted by the enzyme in the viable skin. The first order kinetics of vitamins C and E bioconversion in the viable skin is assumed as the exponential decay law due to skin aging. The developed model is useful when evaluating skin penetration of vitamins C and E. not only to predict the penetration profiles but also to examine how much enzyme in the viable skin affects skin-penetration of vitamins C and E.