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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 17, Issue 5 - Oct 2001
Volume 17, Issue 4 - Aug 2001
Volume 17, Issue E1 - Apr 2001
Volume 17, Issue 3 - Mar 2001
Volume 17, Issue 2 - Feb 2001
Volume 17, Issue 6 - Jan 2001
Volume 17, Issue 1 - Jan 2001
Volume 7, Issue 6 - 00 2001
Volume 7, Issue 5 - 00 2001
Volume 7, Issue 4 - 00 2001
Volume 17, Issue E4 - 00 2001
Volume 17, Issue E3 - 00 2001
Volume 17, Issue E2 - 00 2001
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Impact of Ozonation on Biodegradation of Trihalomethanes in Biological Filtration System
Journal of Korean Society for Atmospheric Environment, volume 7, issue 6, 2001, Pages 349~349
The formation of undesirable chlorinated by-products is related to increasing concentration of ammonia in raw water, present study was investigated in water treated with chlorine where humic acid was used as trihalomethane (THM) precursors. The objective of this study was to clarify the possibility of the biodegradation of THMs adsorbed on granular-activated carbon and determine the adsorption capacity in the bioregenerated granular activated carbon (GAC) by different input ozone concentration. When raw water was reacted with chloride, the yield of THMs was increased as a function of the input amount of chloride. As the input amount of chloride in raw water increased by two or five-fold to remove NH3, the chloroform of THMs was also significantly increased five or ten-fold and the dibromodichloride was increased five-fold. It was found that chloroform was significantly removed in biological activated carbon (BAC) treatment in comparison with ozone treatment, and the removal efficiency of THMs in BAC was reduced by 65% in the BAC column following ozonation due to the biological degradation on the surface of the activated carbons depending upon input ozone concentration.
Preparation of Microcapsules Containing Phase Change Materials as Heat Transfer Media by In-Situ Polymerization
최준규 ; 이재구 ; 김재호 ; 양현수 ;
Journal of Korean Society for Atmospheric Environment, volume 7, issue 6, 2001, Pages 358~358
By controlling adequate preparation conditions and selecting polymer materials as the shell in microencapsulation, shells with various thickness, hardness, aqueous solubility, and molecular weight can be produced. Microcapsules loaded with tetradecane as the core material, which has a high heat capacity, were prepared by in-situ polymerization methods. Melamine-formaldehyde resin was used to form the polymeric shell of the capsules. The size and size distribution of the capsules were determined using an optical microscope and particle size analyzer. The thermal properties were also investigated using a differential scanning calorimeter (DSC), and the durability of the prepared capsules was tested with three kinds of pumps. It was shown that the capsules had a high latent heat capacity, uniform shape and size, and excellent durability. Accordingly, it was demonstrated that the capsules prepared in this study show good performance for the potential application in heat transportation.
Microwave Dehydrogenation of Ethane to Ethylene
김동국 ; 차창열 ; 이우태 ; 김종의 ;
Journal of Korean Society for Atmospheric Environment, volume 7, issue 6, 2001, Pages 363~363
The microwave-induced dehydrogenation of ethane (MDE) into ethylene using various dielectric materials as the catalyst/converter of microwave energy was investigated in a fixed bed reactor located inside a rectangular waveguide of TE(10) mode. Carbonaceous materials including α-SiC showed very good characteristics in a microwave absorption capacity and reactivity for MDE as well as thermal stability. Calculated bed temperatures using a simple equation with dielectric properties were in good agreement with the measured temperatures after one minute of microwave irradiation. The highest ethylene yield and selectivity obtained with Korean anthracite (KAK) for a single pass were 64% and 87%, respectively. The temperature of product gas was very low, ranging from 45 ℃ to 50 ℃. Based on the apparent bed temperatures, ethane conversions with KAK were approximately 10 ~ 15% greater than the equilibrium conversions. The MDE process provides higher ethylene yield and selectivity as well as lower product gas temperature than conventional thermal processes.
Quantitative Analysis of Crocetin Colorants in Gardenias (Gardenia jasminoides Ellis) by LC/DAD/MS
박연실 ; 최흥진 ; 윤석훈 ; 김성환 ; 김태경 ; 윤남식 ; 임용진 ;
Journal of Korean Society for Atmospheric Environment, volume 7, issue 6, 2001, Pages 375~375
For the quantification of yellow coloring materials in gardenia utilized as natural food colorants and for dyeing fabrics, the fruits of fully matured Gardenia jasminoides were characterized by LC/DAD/MS analysis. The five yellow coloring materials with crocetin chromophore were analyzed by HPLC and characterized by DAD and MS analysis. The molar compositions of each crocetin colorant were measured as follows; trans-crocetin di(β-gentiobiosyl) ester 1 [58 mol %], trans-crocetin mono(β-gentiobiosyl) monoglucosyl ester 2 [13 mol %], trans-crocetin diglucosyl ester 3 [20 mol %], crocetin 4 [7 mol %] and trans-crocetin monoglucosyl ester 5 [2 mol %]. With molar absorptivity of the major colorant 1 that was first measured as ε 103000 dm(3) mol(-1) cm(-1) at λ(max) 440 nm, total crocetin content per mass of dried whole gardenia fruit was quantified as 3.4 μ mole/g of crocetin aglycone.
Water Vapor and CO₂Permeabilities of Acrylic Latex Coatings
김준우 ; 이상민 ; 홍종규 ; 임종주 ; 김병식 ; 박상권 ; 홍승민 ; 이현기 ; 박종명 ;
Journal of Korean Society for Atmospheric Environment, volume 7, issue 6, 2001, Pages 380~380
Water vapor permeability (WVP) and CO2 permeability (CDP) are important properties of modern architectural coatings for the protection of building materials such as concrete. A cup method and a high vacuum method were employed to measure the WVP and the CDP, respectively, for three sets of acrylic latex films which were prepared by either single-stage or two-stage emulsion polymerization. For a set of model latex films comprising different combinations of main and auxiliary monomers, it was found that the monomer composition significantly affected the WVP and the CDP. The WVP and the CDP results were explained in terms of the stiffness of polymer chain segments, the crystallinity, and the polarity of the latex films. Compared with the model latex films of a simple core structure containing butylacrylate as a main monomer, the control film of core/shell structure of similar composition showed desirable permeability properties of higher WVP and lower CDP. There was a rough trend of trade-off between the WVP and the CDP of the latex films. Among the model latex films, those containing ethylacrylate monomer showed relatively better behaviors for both the WVP and the CDP. For the other two sets of hard and soft latex films, the WVP for both sets significantly increased with increasing content of hydrophilic microgel particles. As the amount of microgel increased, the CDP for soft latex films was reduced, whereas that for hard latex films slightly increased.
Influence of Liquid Polybutadiene on Properties of Silica-Filled Styrene-Butadiene Rubber Compounds
Journal of Korean Society for Atmospheric Environment, volume 7, issue 6, 2001, Pages 389~389
Polybutadiene is composed of cis-1,4-, trans-1,4-, and 1,2-units. Of the three components, the 1,2-unit has the strongest filler-polymer interaction with silica. In this study, improvement of the filler dispersion in a silica-filled styrene-butadiene rubber (SBR) compound by adding low molecular weight polybutadiene (liquid butadiene rubber, liquid BR) was investigated. The total mixing energy is less consumed by adding the liquid BR to a silica-filled SBR compound. The liquid BR improves the silica dispersion and makes the viscosity lower. The delta torque decreases with increase in the liquid BR content in silica-filled SBR compounds. The Mooney scorch time becomes slower as the liquid BR content increases. The modulus decreases with increasing the liquid BR content due to the decreased crosslink density.
Synthesis and Luminescent Study of Poly(p-phenylenevinylene) Copolymers Containing Pyrazine Moiety
이재성 ; 서정선 ; 조인행 ;
Journal of Korean Society for Atmospheric Environment, volume 7, issue 6, 2001, Pages 396~396
Two pyrazine-containing conjugated copolymers (pyrazine-PPVs) were designed and synthesized to investigate their luminescence properties. The pyrazine-PPVs were synthesized using the Wittig reaction from 2,5-bis(bromomethyl)pyrazine triphenylphosphonium salt and the corresponding dialdehyde. A pyrazine unit was introduced to the main conjugated system to compare the luminescence shift du; to a change of the electron delocalization. A flexible long alkoxy chain was also introduced to maintain a desirable conjugation length. The introduction of pyrazine to the main chain resulted in a slight increase of effective conjugation length and exhibited the red shift in both the absorption and emission spectra.
Studies of the Formation of Polyisoimides and Their Imidization in Solution State
김영준 ; 김지석 ; 최길영 ;
Journal of Korean Society for Atmospheric Environment, volume 7, issue 6, 2001, Pages 400~400
The phthalic anhydride (PA) end-capped polyamic acid was prepared by reacting 4,4'-oxydianiline (4,4'-ODA) with 4,4'-oxydiphthalic anhydride (ODPA) and phthalic anhydride (PA) as an end-capper in N-methylpyrrodidinone (NMP). Subsequently, the end-capped polyamic acid was cyclo-dehydrated using 1,3-dicyclohexylcarbodiimide (DCC) as a dehydrating agent to form corresponding polyisoimide. Syntheses of polyisoimides at five different temperatures of -20 ℃, 0 ℃, 15 ℃, 30 ℃ and 50 ℃ were investigated by employing FTIR spectroscopy. The reaction temperature in polyisoimide synthesis was observed to have a profound effect on the content of polyisoimide. Thus, the % polyisoimide increased with decreasing reaction temperature as a result of the fact that polyisoimide is a kinetically controlled product. The kinetics of thermal imidization of polyisoimide in solution state was also studied. The thermal imidization of polyisoimide was well described by the first order kinetics with the activation energy of 76 KJ/mol and the frequency factor of 4.0 X 10(-7) sec(-1).
Synthesis of Poly(phenylene-co-biphenylene sulfide) and Its Blend with Bisphenol A Polysulfone
유성후 ; 조재영 ; 박이순 ;
Journal of Korean Society for Atmospheric Environment, volume 7, issue 6, 2001, Pages 405~405
A series of poly(phenylene-co-biphenylene sulfide)s (PPBS) were prepared by substituting parts of phenylene units of poly(phenylene sulfide) (PPS) with more rigid biphenylene units. A copolymer was blended with bisphenol A polysulfone (PSF), and drawn to prepare a in situ composite. Dynamic mechanical observation suggested the immiscibility of PSF/PPS blend and the partial miscibility of the PSF/PPBS blend. PPBS appeared to be a better rheology modifier and reinforcing agent than PPS, which is observed in the melt viscosity and the tensile tests. SEM micrographs of the blends show smaller and more uniform domains in PSF/PPBS blends than in PSF/PPS blends. In drawn blends PPBS appeared to form better-defined fibrils with higher aspect ratios than PPS in PSF. As a result PSF/PPBS blend showed higher level of tensile modulus and yield stress over the PSF/PPS blend.
The Methane Reforming with Carbon Dioxide on Ni-Catalyst Activated by a DC-Pulsed Corona Discharge
홍숙원 ; 오승민 ; 박동화 ; 김건중 ;
Journal of Korean Society for Atmospheric Environment, volume 7, issue 6, 2001, Pages 410~410
CO2 reforming of CH4 to the synthesis gas was investigated in a DC pulsed corona discharge with or without the presence of Ni catalyst. It was established that the corona discharge could effectively lower the reaction temperature range of optimum catalytic performance for reforming. The synergy effect could be found in die simultaneous presence of corona discharge and Ni-catalyst for the conversion of methane and carbon dioxide. The synthesis gas yield was enhanced with increasing DC source voltage and resistance time. The higher conversion values were obtained by using Ni-supported on NaX zeolite itself as a catalyst or in conjunction with corona discharge. The obtained synthesis gas was used as a reactant to produce DME under the elevated pressure up to 20 atm, and the effects of reaction conditions and the type of hybrid catalyst were also examined. For the synthesis of DME, Cu/Zn/HY exhibited an efficient catalytic property as compared with more acidic H-Mordenite catalyst.
Modification of Mesoporous γ-Alumina with Silica and Application for Hydrogen Separation at Elevated Temperature
서봉국 ; 이규호 ;
Journal of Korean Society for Atmospheric Environment, volume 7, issue 6, 2001, Pages 417~417
Amorphous silica membranes were deposited by thermal decomposition of tetraethoxysilane(TEOS) at 600 ℃ on a γ-alumina coated α-alumina tube with pore size of 6-8 nm. The forced cross flow through the porous wall of the support was very effective in plugging macropores. The silica modified layer was extended to a depth of 200 nm and the top surface of the film was quite smooth without pinhole. The silica membrane showed a hydrogen permeance of 1.41 X 10(-7) mol . m(-2).s(-1).Pa-1 and a H2/N2 selectivity of about 20 at a permeation temperature of 450 ℃. The permeation tests with CO2, N2, CH4 and C3H8 showed that a very small number of mesopores remained unplugged by the CVD. Permeation of hydrogen was explained by activated diffusion, and that of the other gases by Knudsen diffusion through the unplugged pores. Thus, the total permeance was comprised of permeances due to the activated and Knudsen diffusion mechanisms. The CVD-modified silica membrane was stable in a H-2-N-2 mixture of 450 ℃ for 100 h.
Selective Synthesis of Furfural from Xylose with Supercritical Carbon Dioxide and Solid Acid Catalyst
김영철 ; 이현섭 ;
Journal of Korean Society for Atmospheric Environment, volume 7, issue 6, 2001, Pages 424~424
Furfural is consumed in its synthetic condition by several side reactions, thereby generating lots of reaction byproducts. The conventional synthetic process is based on the catalysis of xylose by sulfuric acid. Therefore, a large amount of process waste is generated as the spent acid catalyst in addition to the byproducts. A new process principle is proposed in this paper through which furfural can be synthesized in an environmentally benign way. Furfural was synthesized in its high yields even at the high conversions of xylose by utilizing solid acid catalysts and extracting it from the reaction media with supercritical fluid as soon as it is formed. Sulfated titania and sulfated zirconia were prepared and used as the model solid acid catalysts, and supercritical carbon dioxide was distributed in the reaction media as the extracting solvent. The effects of introducing the supercritical fluid were investigated in depth on the correlation among conversion, selectivity, and yield of the synthesis. The reaction model, proposed by Sako et al., reproduced the extraction effects of furfural by supercritical fluid in fairly good agreements. The supercritical fluid extraction was found to be effective enough to overcome the mass-transfer resistance existing in the solid catalysts.
Evaluation of Organic Sulfonic Acids as Catalyst during Cellulose Liquefaction Using Ethylene Carbonate
문성필 ; El-Barbary M. Hassan ; 윤태호 ;
Journal of Korean Society for Atmospheric Environment, volume 7, issue 6, 2001, Pages 430~430
Cellulose liquefaction was successfully conducted using ethylene carbonate (EC) as a liquefying agent and organic sulfonic acids, such as methanesulfonic acid (MSA) or p-toluenesulfonic acid (PTSA), as a catalyst. Due to the higher crystallinity of cellulose, organic sulfonic acids were more effective at higher temperatures (170 ~ 180 ℃). Consequently, at 180 ℃ with 3.58 mmol of organic sulfonic acid catalysts, liquefaction yield was about 99% compared to 80% at 150 ℃ and with 8.95 mmol. In addition, at 180 ℃, the rate of reaction using MSA was approximately 5 times faster than at 150 ℃. Sulfuric acid (SA) was more effective than the organic sulfonic acids at lower acid concentrations and temperatures. FTIR spectroscopy of the residue revealed a strong carbonyl band when SA was used as the catalyst, indicating more decomposition of the cellulose. An X-ray analysis showed similar crystallinity results for the cellulose and the residue that remained after liquefaction, indicating that most of the residue was derived from the crystalline area of cellulose.
Nanopowders Synthesized by Thermal Plasma
오승민 ; 공정구 ; 박동화 ;
Journal of Korean Society for Atmospheric Environment, volume 7, issue 6, 2001, Pages 435~435
Nano-sized TiO2 powders were synthesized from TiCl4 and SiCl4 using thermal plasma. The effect of dopant SiCl4 on the characteristics of TiO2 powder was investigated. The result was that anatase phase increased with the feed rate Of SiCl4. Also, phase composition of the powder was influenced by collection position and these powder morphology and phase compositions were analyzed by XRD, SEM, TEM/EDS, FT-IR. At the reaction tube, the powder was mainly obtained as rutile, while at the collection vessel it was mainly obtained as anatase. The synthesized powders were estimated for the photocatalytic activity by photochemical reaction of acetaldehyde under UV-irradiation. The photodestruction rates of acetaldehyde increased with the content of anatase in the powders. The dopant SiCl4 increased the content of anatase but Si species in the powder led to decrease the photodesrtruction rates of acetaldehyde.
Characterization and Acid Catalytic Properties of Titanium Sulfate Supported on Zirconia
손종락 ; 권태동 ; 김상복 ;
Journal of Korean Society for Atmospheric Environment, volume 7, issue 6, 2001, Pages 441~441
Titanium sulfate supported on zirconia catalysts were prepared by drying of powdered Zr(OH)4 with titanium sulfate aqueous solution followed by calcining in air at high temperature. The characterization of prepared catalysts was performed using Fourier transform infrared (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and by the measurement of surface area. The addition of titanium sulfate to zirconia shifted the phase transition of ZrO2 from amorphous to tetragonal to higher temperature due to the interaction between titanium sulfate and zirconia, and the specific surface area and acidity of catalysts increased in proportion to the titanium sulfate content up to 5 wt% of Ti(SO4)2. Infrared spectra of ammonia adsorbed on Ti(SO4)2/ZrO2 showed the presence of Bronsted and Lewis acid sites on the surface of Ti(SO4)2/ZrO2. 5-Ti(SO4)2/ZrO2 calcined at 600 ℃ exhibited maximum catalytic activities for 2-propanol dehydration and cumene dealkylation. The catalytic activities for both reactions, 2-propanol dehydration and cumene dealkylation were correlated with the acidity of catalysts measured by ammonia chemisorption method.
Curing Behavior of Epoxy Resins Using Aminolysis Products of Waste Polyurethanes as hardeners
김병철 ; 이대수 ; 현송원 ;
Journal of Korean Society for Atmospheric Environment, volume 7, issue 6, 2001, Pages 449~449
We carried out aminolyses of various rigid polyurethane foams (PUFs) using diethylene triamine and studied the application of aminolysis products as hardners of epoxy resins. Diglycidyl ether of bisphenol A was used for the study on the curing behavior of epoxy resin with the aminolysis product employing differential scanning calorimetry. Curing reaction of the epoxy resin is generally known to be autocatalytic second order reaction. We found that the curing reaction of the epoxy resin with the aminolysis product of rigid PUF did not show autocatalytic characteristics but followed the n-th order kinetics. The activation energy in curing reaction of the epoxy resins by using the aminolysis products of rigid PUFs was nearly identical irrespective of types of PUFs.