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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 & Issues
Volume 16, Issue 4 - Aug 2000
Volume 16, Issue 6 - Jun 2000
Volume 16, Issue 3 - Jun 2000
Volume 16, Issue 5 - May 2000
Volume 16, Issue 2 - Apr 2000
Volume 16, Issue 1 - Feb 2000
Volume 6, Issue 6 - 00 2000
Volume 6, Issue 5 - 00 2000
Volume 6, Issue 4 - 00 2000
Volume 6, Issue 3 - 00 2000
Volume 16, Issue E - 00 2000
Volume 16, Issue E2 - 00 2000
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Conjunctice Use of Ultrafiltration with Powdered Activated Carbon Adsorption for Removal of synthetic and Matural Organic Matter
이성진 ; 조광호 ; 이청학 ;
Journal of Korean Society for Atmospheric Environment, volume 6, issue 6, 2000, Pages 357~357
In a combined powered activated carbon - ultrafilltration (PAC-UF) system, the removal of organic matter and the behavior of membrane fouling were investigated for the treatment of water containing different concentrations of o-dichlorobenzene (DCB) and humic acids as synthetic and natural arganic compounds, respectively.The humic acid removal efficiencies were more significantly dependent on the membrane properties than on the PAC dosage during UF. However, the DCB removal efficiencies were affected by the qrantity of humic acids present in the feed water as well as the membrane material and PAC dosage. The binding of DCB to humic acids by complextion contributed to a greater DCB removal at a higher humic acid concentration, particularly with the cellulose acetate membrane. Although PAC addition to the UF system was acticipated to improve the membrane flux through removing organic matter by adsorption, instead, the actual flux decreased and more humic acids were deposited on the membranes. Accordingly, it would appear that aggregation of humic acids, possibly facilitated by PAC adsorption, resulted in more severe fouling at the membrane suface.
Synthesis of Mondisperse SiO₂and TiO₂Nanoparticles using Semibatch Reactor and Comparison of Parameters Effection Particle Size and Particle Size Distribution
박성규 ; 김기도 ; 김희택 ;
Journal of Korean Society for Atmospheric Environment, volume 6, issue 6, 2000, Pages 365~365
Monodisoerse SiO₂ and TiO₂nanoparticles were synthesized from tetraethyl ofthosilicate (TEOS) and tetraethyl in ethanol, respectively, using a semibatch method which was found to be easier than a batch process in controlling the size, shape, and size distribution. In this study, a statistical experimental method was also used to compare the properties (particle size and standard deviation) of the SiO₂ and TiO₂particles according to the paramenters [R=(H₂O/TEOS]): 31, concentration of ammonia: 0.32 mol/l, feed rate of reactant: 17 ml/min, reaction temperature: 62℃, (2)TiO₂;[R=[H₂O/TEOS]): 16, HPC: 0.0028 g/ml, feed rate of reactant: 0.6 ml/min, reaction temperature: 30℃. Using the above optimal conditions, particles of SiO₂(13.7 nm) and TiO₂(10.6nm) with a narrow size distribution were prepared. In addition, it was found that the main parameters affecting the preparation of SiO₂ and TiO₂ nanoparticles decreased in the order of the feed rate of the reactant > NH₃/ HPC> R(H₂O/TEOT)> the reaction temperature.
Silica Agglomerate Breakdown in Three-Stage Mix Including a Continous Ultrasonic Extruder
김광재 ; James L. White ;
Journal of Korean Society for Atmospheric Environment, volume 6, issue 6, 2000, Pages 372~372
The dispersive mixing of premixed nano-size untreated and treated silica particles, and compounds in ethylene-propylene-diene terpolymer (EPDM) were studied using an ultrasonic extruder (Ultra) and compared with an internal mixer (Int) processing.The rheological properties and extrudate swell of the compounds were investigated and compared with carbon black filled compounds. The Ultra processing broke down the silica exhibited a considerable reduction in the agglomerate sizes compared to the untreated silica in an Int. These results were then compared with carbon black filled compounds. The viscosity of the compounds with untreated and treated silica was higher than the compound with carbon black. This may be due to the rough surface of the silica particles. The silane treated compounds exhibited a lower viscosity than the untreated compounds. The effect of extrudate swell reduction was minimal on the treated compounds.
Characteristics of Hydrogen Absorption by Zirconium and Titanium
이성호 ; 정홍석 ;
Journal of Korean Society for Atmospheric Environment, volume 6, issue 6, 2000, Pages 380~380
Hydrogen absorption experiments were carried out using the zirconium (Zr) and titanium (Ti) in the form of a metal sponge, strip and to investigate the characteristics of hydrogen absorption. The Zr and Ti sponges showed a high hydrogen absorption capacity inspite of a low reaction temperature. The H/M, which indicates the capacity of hydrogen absorption, was measured at 2.0 for the Zr and Ti sponges under experimental condition of 25℃. However, in the case of the Zr and Ti strip and rod, the hydrogen absorption capacity was very low at 25℃. But, the capacity of hydrogen absorption increased with an increase in the reaction temperature. When the Ti strip was not activated, the H/M ratio was mezsured at 0.58. But, when the Ti strip was once and twice activated at 800℃ for 1 h, the H/M ratio increased to 1.6 and 1.83, respectively. A pulverizing phinominon during the metal hydriding was observed in both the Zr/Ti strip and the Zr/Ti rod. However, this pulverizing phinomenon was not observed in the Zr and Ti sponges because of their high surface area.
Development of Performance-Analysis Program for Vapor-Compression Cycle based on Thermodynamic Analysis
김영재 ; 박인섭 ;
Journal of Korean Society for Atmospheric Environment, volume 6, issue 6, 2000, Pages 385~385
In this paper, a computer program called Ref_Cycle, which simulates the steady-state performance of conventional vapor-compression refrigeration systems, is illustrated and tested using various case studies. It would appear to be advantageous to use Ref_Cycle for a preliminary performance analysis when considering various kinds of refrigerants and the comples operating conditions of each unit making up the vapor-compression cycle. Moreover, Ref_Cycle would seem to be a very useful tool in optimizing a refrigeration system and estabilshing economical and efficient operating comditions in the vapor-compression cycle. The simulation code created by the current authors was programmed with Visual Fortran for the main simulation code and Visual
for the graphic user interface. In Ref_Cycle the thermocynamic properties of the refrigerants are estimated using REFPROP V6.0.
Hydrogen Bubble Characteristics during a Water-Sodium Lead Accident in a Steam Generator
김태준 ; Valery S. Yughay ; 황성태 ; 김병호 ; 박진호 ; 최청송 ;
Journal of Korean Society for Atmospheric Environment, volume 6, issue 6, 2000, Pages 395~395
Hydrogen bubble characteristics, the parameters of a defect in a steam generator heat-transfer tube, resonant frequencies and initial bubble radii can all be experimentally calculated using micro-lead rates resulting from a water/steam-into-liquid-sodium injection. The conditions of this experiment were sodium temperatures of 300, 400, and 500 ℃ and water injection rates of 0.005, 0.03, 0.08, and 0.183 g/sec. The acoustic spectra and hydrogen bubble frequency for a leak rate of 0.005 g/s were measured. Thereafter, the initial radius of hydrogen bubbles in sodium. Since the lifetime of hydrogen bubbles with a radius of about 3 mm was not more than 3 sec, the acoustic detection of a water/steam-into-sodium leak addident in a KALIMER (Korea Advanced Liquid Metal Reactor) steam generator can satisfy the safety requirments.
Salt Permeation through Cationic Poly(chloromethylstyrene-co-divinylbenzene) Membranes
송기찬 ; 김수경 ;
Journal of Korean Society for Atmospheric Environment, volume 6, issue 6, 2000, Pages 403~403
Poly(chloromethylstyrene-co-divinylbenzene)-based cationic membranes were prepared with different amounts of 2-methyl-2-butanol and divinylbenzene. The membrane characteristics such as the morpholohy, water content, density and fixed charge density of the preparation conditions of cationic membranes were investigated. With increasing the amount of 2-methyl-2-butanol, the water content and apparent density increased, whereas the fixed charge density in the membrane decreased. The dependence of the permiabilities on the upstream salt concentration changed into three forms by the increase of water content, i.e., permeability minima, TMS mode and concentration independence. These results, together with the sorption isotherms, were discussed assuming a dual sorption and diffusion mode, that is, partition under Donnan exclusion and Langmuir type.
Drag Reduction Rates and Degradation Effects in Synthetic Polymer Solution with Surfactant Additives
김남진 ; 이재영 ; 김종보 ; 허병기 ;
Journal of Korean Society for Atmospheric Environment, volume 6, issue 6, 2000, Pages 412~412
The turbulent flow friction of a water solution with a small amount of polymer additives is dramatically reduced when compared to that of pure water. This effect is called the drag reduction and offefs a significant reduction in pumping power and energy consumption. However, in the flow can cause a loss in the drag reduction effectiveness due to degradation in the polymer solutions. This degradation behavior of polymers has also been found to be strongly dependent on temperature. Accordingly, the present study investigated whether mechanical and thermal degradation could be effectively avoided by adding caterials such as a surfactant to the polymer solution, thereby enhancing the bonding forces between the polymer molecules. In the current investigation, a synthetic polymer (Copolymer) and surfactant (SDS) were utilized, which were mixed in 10 different mixture ratios, while the total additive concentrations were fixed at 100wppm. The degradation of the Copolymer-SDS mixture solutions was esperimentally investigated in a closed loop at 10℃ and 80℃ with various flow velocities at 1.5m/sec, 3.0m/sec, and 4.5m/sec. The degradation characteristics of those polymer solutions without a surfactant showed a dramatic loss in their drag reduction rates at high temperatures. The degradation alleviation ability of the surfactant was found to be particularly effective at high temperatures. Consequently, it was shown that the addition of a surfactant to a polymer solution can effectively control unfavorable degradation phenocena especially in high-temperature flow systems.
Mechanical Properties of Unaged, Air-, and Oil-Aged ACM/ENR Blends
박찬영 ; 박상보 ; 민성기 ;
Journal of Korean Society for Atmospheric Environment, volume 6, issue 6, 2000, Pages 419~419
The blending of acrylic rubber (ACM) with epoxidized natural rubber (ENR)-50 was carried out on an apen 2-roll mill following the conventional polymer blend method, then other ingredients were added. Vulcanized sheets were prepared using a hot press, then mechanical properties of the ungaed vulcanizates and those of the air- and oil-aged ones were measured. The hardness of the vulcanizates was probaly increased due to the post cure during the agingtest. With the immersion of the rubber specimens in hot oil, the hardness was decreased followed by a swelling of the rubber matrix with oil penetration into the rubber molecules. Presumably, the elongation was also decresased with heat aging owing to the elevation of the hardness through the post cure.
Polyurethane Anionomers Based on Poly(butylene succinate), 4,4'-Methylenebis(phenyl isocyanate), and 2,2-Bis(hydroxymethyl)Propoinic acid
오효진 ; 김완영 ; 이대수 ; 이윤식 ;
Journal of Korean Society for Atmospheric Environment, volume 6, issue 6, 2000, Pages 425~425
Polyurethanes may be able to replace biodegradable polyesters since the biodegradability and certain mechanical properties of polyurethanes can adjusted by modifying their chemical structrues. A prepolymer was prepared from poly(butylene succinate) diol (MW 1600) and 4,4'-methylenebis(phenyl isocyanate), and chain-extended with 2,2-bis(hydroxymethyl)propionic acid (DMPA). The resulting polyurethane (PU) was neutralized with a base to obtain polyurethane ionomers (PUIs). The thermal transitions of the PUIs were not much different from those of the PU. However, the mechanical strengths were greater than both the PU and a typical biodegrdable aliphatic polyester. For those PUIs in which the degree of neutralization with NaOH was 50% and 100%, the hydrolytic degradation was very rapid in a 5% NaOH solution at 37℃. Their weight loss was approximately 30 and 50% within 2 days, respectively, while the PU was degraded only about 15% under the identical conditions. Some polyesters (Mn 40000 and 80000) underwent a degradation of about 10-20%. Accordingly, this study suggests that the PUIs can be applicable to the fabrication of degradable plastic materials.
Investigation of Process Optimization in Synthesis of Thioxanthone from 2,2'-Dithiobenzoic Acid and Cumene
박연실 ; 김준길 ; 최형진 ;
Journal of Korean Society for Atmospheric Environment, volume 6, issue 6, 2000, Pages 431~431
The synthesis of isopropylthioxanthone, a photoinitiator, from 2,2'-dithiobisbenzoic acid (DTSA) or thiosalicylic acid (TSA) and cumene in sulfuric acid was investigated in the perspective of the reaction mechanism and stoichiometry. The yield of product was sensitive to the strength of sulfuric acid used as the reaction medium. With a higher strength of sulfuric acid, a higher yield of product was obtained. The substitution of DTSA with cumeno to the isoceric products, 2-isopropylthioxanthone 3, and 4-isopropylthioxanthone4, via thioarylether intermediates 5 and 6 respectively is an oxidative reaction and requires oxidants in the reaction system. Fuming sulfuric acid containing oxidative sulfur trioxide resulted in a high yield of product by accelerating the formation of intermediates 5 and 6 in contrast to the competitive sulfonation in sulfuric acid that increased the content of water in reaction medium and resulted in low yield of product due to the retardation of the formation of intermediates 5 and 6. The ratio of isomeric products 3 over 4 varied with the strength of the sulfuric acid: A stronger strength of sulfuric acid produced relatively higher content of 3 over 4. The optimized reaction conditions were five parts by weight of DTSA and ten parts by weight of cumene per one part by weight of DTSA for two hours at room temperature, which yielded 78% of products 3 and 4 (91:9) after vacuum distillation.
Physical Properties of Ultra-High Molecular Weight Polyethylene in Retrieved Artificial Knee Joint
신효섭 ; 이춘수 ; 조재영 ; 최귀원 ; 배대경 ;
Journal of Korean Society for Atmospheric Environment, volume 6, issue 6, 2000, Pages 437~437
Physical properties of ultra-high molecualr weight polyethylene (UHMWPE) in retrieved artificial knee joints were investigated. Lamella thickness, crystallinity, and mechanical chain scission apperared to increase during service. Crystallinity-depth profile was related to the conformity of joint and the thickness of tibial component. For the joint of low conformity, stress, crystallinity, and lamellae alignment were highest at subsurfac 1-2 mm beneath the surface, whrer crack propagation and delamination eventully occurred, It was suggested that the thickness and conofrmity of UHMWPE part should be increased for better wear-resistant tibial component of knee joint prosthesis.