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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Korean Society for Atmospheric Environment
Journal Basic Information
Journal DOI :
Korean Society for Atmospheric Environment
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Volume & Issues
Volume 15, Issue 6 - Dec 1999
Volume 15, Issue 5 - Oct 1999
Volume 15, Issue 4 - Aug 1999
Volume 15, Issue 3 - Jun 1999
Volume 15, Issue 2 - Apr 1999
Volume 15, Issue 1 - Feb 1999
Volume 5, Issue 4 - 00 1999
Volume 5, Issue 3 - 00 1999
Volume 15, Issue E - 00 1999
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Hydrothermal Stability of Mesoporous Molecular Sieve Synthesized from Fluorosilicon Compound
정호성 ; 정순용 ; 이정민 ; 임대재 ; 류성곤 ;
Journal of Korean Society for Atmospheric Environment, volume 5, issue 4, 1999, Pages 247~247
Pure silica mesoporous molecular sieves were synthesized from a fluorosilicon compound in which the cationic surfactant had been removed either by calcination or acidified solvent extraction at atmospheric pressure. The mesoporous materials prepared by direct calcination and extraction were heated up to 100 ℃ at a sample/water ratio of 1 g to 1000 mL during 12-24 h in order to investigate the hydrothermal stability. The change of structure caused by XRD, nitrogen adsorption/desorption, TEM, and TGA was measured. It was found that the material prepared by direct calcination maintained a mesopore structure after hydrothermal treatment for 12 h, however, this mesopore structure collapsed after hydrothermal treatment for 18 h due to hydrolysis in the Si-O-Si linkages. The samples prepared by the extraction process exhibited no significant change in their mesopore structure even after hydrothermal treatment for 18 h. In the case of the samples treated hydrothermally for 24 h, the pore size distributions showed a narrow uniform mesopore from 20 to 30 Å. However, the pore structure of the samples was less uniform than that of the non-treated samples. Accordingly, it can be concluded that materials prepared by extracting the surfactant with organic solvents have more hydrothermal stability than materials prepared by direct calcination. These results can be explained by an increase in the wall thickness, and decrease of the silanol group in the mesopore structure.
Characterization of Cobalt Sulfate Supported on Zirconia and Activity for Acid Catalysis
손종락 ; 박은희 ; 김혜원 ;
Journal of Korean Society for Atmospheric Environment, volume 5, issue 4, 1999, Pages 253~253
Cobalt sulfate supported on zirconia catalysts were prepared by drying powdered
with a cobalt sulfate aqueous solution followed by calcining in air at a high temperature. The characterization of the prepared catalysts was performed using Fourier transform infrared (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and by the measurement of the surface area. The addition of cobalt sulfate to zirconia shifted the phase transition of
from amorphous to tetragonal to higher temperature due to the interaction between the cobalt sulfate and the zirconia, and the specific surface area and acidity of catalysts increased in proportion to the cobalt sulfate content up to 6 wt % of
. Infrared spectra of the ammonia adsorbed on the
showed the presence of Bronsted and Lewis acid sites on the surface of the
calcined at 600∼650 ℃ exhibited the maximum catalytic activities for 2-propanol dehydration and cumene dealkylation. The catalytic activities for cumene dealkylation were roughly correlated with the acidity of the catalysts measured by the ammonia chemisorption method.
Photooxidation of EDTA on TiO₂
정흥호 ; 노재성 ;
Journal of Korean Society for Atmospheric Environment, volume 5, issue 4, 1999, Pages 261~261
This study investigated the availability of TiO₂ photo-catalysis for the aqueous-phase oxidation of Ethylenediaminetetraacetic acid (EDTA). The tendency of EDTA adsorption onto the catalyst surface was affected by the TiO₂ surface charge, and the oxidation rate of EDTA by photo-catalysis was shown to depend upon the tendency of EDTA adsorption before photo-irradiation. Oxygen enhanced the photooxidation rate of EDTA. The photooxidation rates of EDTA were determined for initial EDTA concentrations ranging from 0.89 mM to 8.91 mM. The experimental data showed that the photooxidation process of free-EDTA followed Langmuir-Hinshelwood kinetics.
Synthesis of Branched Polycarbonate and Properties of Blends with Linear Polycarbonate
김상필 ; 이재식 ; 김선호 ; 이봉희 ; 김상헌 ; 김환기 ;
Journal of Korean Society for Atmospheric Environment, volume 5, issue 4, 1999, Pages 268~268
The relative reactivities for linear and branched polycarbonates prepared from 1,1,1,-tris-p-hydroxyphenylethane (THPE) as a branching agent were investigated in batch reactors. The polymerization was based upon phosgenation, followed by condensation with triethylamine as a catalyst. The relative kinetic studies of branched polycarbonate system showed that the reaction rates in the polycondensation stage were faster than those of the linear polycarbonate. The melt and mechanical properties of the linear/branched polycarbonate blends were also measured. Interestingly, the melt flows showed different behaviors when branched polycarbonate acted as the minor and major components, especially under high shear.
Effects of Natural Zeolite Content on Electrical Insulting Characteristics of DGEBA/MDA/SN System
김유정 ; 김상욱 ;
Journal of Korean Society for Atmospheric Environment, volume 5, issue 4, 1999, Pages 274~274
The electrical insulating characteristics of the dehydrated zeolite filled DGEBA (diglycidyl ether of bisphenol A)/MDA (4,4'-methylenedianiline)/SN (succinonitrile) system were studied. The dielectric breakdown strength of cured specimens was measured using needle-plane electrode geometry, and the effects of natural zeolite on the electrical insulating properties discussed. As the zeolite content increased, the dielectric breakdown strength increased, and the time until the complete puncture by the tree channels also increased due to the barrier effect of the zeolite particles. The electrical tree channel propagated along the weak point of interface between the zeolite and the epoxy resin, As the zeolite content increased, the dissipation factor and relative permittivity both increased to convergent values of 0.085 and 6.98, repectively. The average volume resistivity was 2.2×
Adhesion and Thermal Properties of Rosinamideimide Modified with Polysiloxane
강두환 ; 김영민 ;
Journal of Korean Society for Atmospheric Environment, volume 5, issue 4, 1999, Pages 280~280
Rosin maleic anhydride adduct (RMA) was prepared by Diels-Alder reaction of rosin with maleic anhydride. Methylphenylcyclotrisiloxane (
) was synthesized from methylphenyldichlorosilane in the presence of zinc oxide catalyst, and then polymerized at 90 ℃ for 24 h to obtain amino group terminated polymethylphenylsiloxane prepolymer (APPS). Rosinamideimide was prepared from the polycondensation of RMA with APPS at 120 ℃ for 6 h in the presence of triphenylphosphite catalyst. The structure and thermal properties of the polymer were characterized by FT-IR, NMR(
), DSC, and TGA. Rosinamideimide showed good thermal stability and adhesion to aluminum metal substrate.
was 259 ℃, however
was not observed. The residual weight (
) at 500 ℃ was 55%, and the adhesion strength was 1.45 MPa.
Preparation and Characterization of Poly(methylmethacrylate-co-ethylene glycol dimethacrylate) Microgels
김영식 ; 김공수 ; Neil B. Graham ;
Journal of Korean Society for Atmospheric Environment, volume 5, issue 4, 1999, Pages 285~285
Internally crosslinked polymer microgels were obtained with various molar ratios of methyl methacrylate/ethylene glycol dimethacrylate (MMA/EGDMA) using the solution polymerization method. For each molar ratio of MMA/EGDMA used, there was a critical gelation concentration of monomers for the microgel formation. Poly(methylmethacrylate-co-ethylene glycol dimethacrylate) microgel was soluble in various organic solvents and melted at a certain temperature. The physical properties of the microgels such as the intrinsic viscosity, coil density, molecular weight, particle size, and thermal properties were also investigated. It was observed that the microgels are compact and spherical particles within a range of 50∼100㎛. However the microgel particles were slightly elongated and aggregated at high monomer concentrations and molar ratios of MMA/EGDMA.
Poly(p-phehylene)s via Pd(0) Catalyzed Cross-coupling of Arylene Bistriflate with Arylene Bisboronic Acid
정동준 ; 배진영 ;
Journal of Korean Society for Atmospheric Environment, volume 5, issue 4, 1999, Pages 290~290
This paper describes the synthesis and characterization of functional poly(p-phenylene)s (PPPs) based on palladium(0) catalyzed "Suzuki-type" cross-coupling reaction of aryl bistriflates derived from substituted hydroquinones with aryl bisboronic acids or its ester in the presence of a base. The effect of various reaction conditions such as palladium catalyst, solvent, base and additives on the reaction yield and the molecular weight of the polymer is discussed.
Ion Exchange Characteristics of Rhodium from a Simulated Radioactive Liquid Waste
이성호 ; 김광락 ; 손종식 ; 유재형 ; 정홍석 ;
Journal of Korean Society for Atmospheric Environment, volume 5, issue 4, 1999, Pages 296~296
Radioactive liquid waste contains significant quantities of platinum group metals such as palladium (Pd), rhodium (Rh) and ruthenium (Ru). There are many techniques, such as solvent extraction, precipitation, ion exchange, and adsorption methods, for the separation and recovery of Rh. In this study, batch and column experiments were carried out to investigate the ion exchange and elution characteristics of Rh from a simulated radioactive liquid waste by commercial cation and anion exchange resins such as Dowex 50W, IRN 78 and Dowex 1×8. The effects of the ionic group of resins, the solution temperature, and the concentration of nitric acid were investigated. Also, the elution characteristics of Rh by various eluents were studied.
Simulation Study of Behavior of β-Amyloid Peptide (β AP) on Lipid Membrane using Cellular Automata (CAs)
송영욱 ; 심미자 ; 김상욱 ;
Journal of Korean Society for Atmospheric Environment, volume 5, issue 4, 1999, Pages 302~302
To study the various behaviors of β-amyloid peptide (βAP) on the surface of the lipid membrane, the penetration and aggregation of βAP were simulated by cellular automata (CAs). A cellular automata simulation is a discrete computing mechanism, which expands a local area result to a complex system. When βAP approached the lipid membrane, the following simulation results were displayed. As the hydrophobic C-terminal domain approached the lipid membrane, the peptide penetrated into the membrane, while N-terminal of the peptide aggregated. For the purpose of penetration and aggregation modelling, the simulations of the C-terminal domain entering into the lipid membrane and the N-terminal domain on the surface of the lipid membrane were presented by cellular automata. These results have some similarity with the behavior of βAP in the human brain which confirms that the behavior of βAP can be simulated by cellular automata.
Lipid Nanospheres Containing Vitamin A or Vitamin E: Evaluation of Their Stabilities and In Vitro Skin Permeability
김소연 ; 이영무 ;
Journal of Korean Society for Atmospheric Environment, volume 5, issue 4, 1999, Pages 306~306
To encapsulate a fat-soluble vitamin, lecithin composed of several hydrogenated phospholipids obtained from soybean and an adjuvant were used. The resulting lipid nanospheres were about 200-300 nm in size and had a monodispersed-size distribution. Increasing the proportion of the oil phase produced large lipid droplets. The size and zeta-potential of a lipid nanosphere containing a 10 w/w% oil phase decreased with an increased proportion of lecithin and then leveled off with a lecithin content of about 1.2 w/w%. Furthermore, an attempt was made to improve the stability of a lipid nanosphere consisting of vitamin and lecithin by coating the surface of the lipid layer with several emulsifiers that had different hydrophilic lipophilic balance (HLB) values and molecular weights. The lipid nanosphere emulsion prepared with only lecithin showed a significant coalescence over a storage period of 60 days. However, the size of the lipid nanosphere was smaller and its in vitro stability was significantly improved compared with other formula, when Tween 80 was used as the cosurfactant. In particularly, the lipid nanosphere with the minimum size and maximum stability had a 1 : 1 content ratio of lecithin to Tween 80. From in vitro permeation experiments using rat skin, it was found that the permeation of the vitamin from a lipid nanosphere was greater than that of free vitamin A or E, and varied depending on the composition and size of the lipid nanosphere.
Simple Silica-Pillaring Route into Layered Phase: Simultaneous Intercalation of Amine-TEOS into
-magadiite and Amine Catalyzed-Interlamellar Hydrolysis of TEOS
Journal of Korean Society for Atmospheric Environment, volume 5, issue 4, 1999, Pages 314~314
The simultaneous intercalation of an amine and TEOS [tetraethylorthosilicate,
-magadiite in an amine-TEOS solution solution resulted in mesoporous silica-pillared
-magadiites (SPM) through the successive interlamellar hydrolysis of TEOS in water. The results indicate that an interlayer amine acts as a gallery height expander as well as a base catalyst and template during the interlamellar hydrolysis of TEOS. The hydrolysis of the gallery TEOS resulted in siloxane-pillared
-magadiites with a gallery height between 20.5 and 33.5 Å. The calcination of the samples at 538 ℃ in air resulted in silica-pillared magadiites with large specific surface areas between 511 and 769 ㎡/g, depending on the reaction stoichiometry, chain length of the amine, and gelation mediums. This process can greatly simplify the silica-pillaring process, because the silica-pillaring is performed effectively for a short time using only a small amount of reagent without pre-intercalation by amine or quaternery ammonium cation.