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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 14, Issue 6 - Dec 1998
Volume 14, Issue 5 - Oct 1998
Volume 14, Issue 4 - Aug 1998
Volume 14, Issue 2 - Apr 1998
Volume 14, Issue 3 - Mar 1998
Volume 14, Issue 1 - Feb 1998
Volume 4, Issue 4 - 00 1998
Volume 4, Issue 3 - 00 1998
Volume 14, Issue E - 00 1998
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Simultaneous Catalytic Removal of NO and Carbon Particulates Over Perovskite-type Oxides
양진섭 ; 이건대 ; 안병현 ; 홍성수 ;
Journal of Korean Society for Atmospheric Environment, volume 4, issue 4, 1998, Pages 263~263
We have studied the simultaneous removal of carbon particulate and NOx over perovskite-type oxides prepared by malic acid method. The catalysts were modified to enhance the activity by substitution of metal into A- or B- site of perovskite oxide. In the LaCoO3 catalyst, the partial substitution of Cs into A-site enhanced the catalytic activity in the combustion of soot particulate and NO reduction. In the Cs-substituted oxide, the ignition temperature of carbon particulate slightly decreased in the order Co > Mn> Fe of B-site metal cation but NO conversion showed almost similar values. With increasing NO concentration, NO conversion decreased but the ignition temperature moved to high temperature when the NO concentration was higher than 1000 ppm. The carbon particulate played an important role on the reduction of NO, but NO had little effect on the oxidation of carbon particulate
Adsorption of Cobalt(Ⅱ) Ion on Anhydrous Titanium Dioxide at Elevated Temperature
김광락 ; 김우철 ;
Journal of Korean Society for Atmospheric Environment, volume 4, issue 4, 1998, Pages 270~270
TiO2 adsorbents were prepared by hydrolysis of Ti(OC 3H7)4 followed by heat treatment of their hydroxides. Their structures were studied by X-ray diffractometer and Fourier-transform infrared spectrometer as a function of preparation pH. The Co2+ adsorption characteristics of the adsorbent in high temperature water were investigated in a stirred autoclave. Co2+ adsorption capacity of the TiO2 adsorbent was determined to be 0.09 meq·g-1 adsorbent in 280℃ of high temperature water. enthalpy change (ΔHo) of about 34 kJ·mol-1 due to the adsorption of Co2+ on the TiO2 indicates that the adsorption is endothermic in the experimental temperature range (150-280℃). It was shown that specific surface area and surface OH groups of these adsorbents are not a dominant factor for Co2+ adsorption on oxides at a high temperature.
Solubility of Rare Earth Oxalate in Oxalic and Nitric Acid Media
정동용 ; 김응호 ; 이일희 ; 유재형 ;
Journal of Korean Society for Atmospheric Environment, volume 4, issue 4, 1998, Pages 277~277
The solubilities of rare earth(Y, La, Ce, Nd, Sm, Eu, Gd, Dy, Er, and Yb) oxalates were measured in nitric acid and oxalic acid media. The concentration of rare earth in the filtrate obtained after oxalate precipitation was determined by ICP-AES. The experiment revealed that the solubilities decreased as the oxalic acid concentration increased and the nitric acid concentration decreased. Based on the assumption that rare earth ions can react with oxalate ion to form RE(C2O4) n3-2n(n = 1,2,3) complex, we have proposed a solubility model of rare earth oxalate. The oxalic acid concentration, the hydrogen ion concentration, and the ionic strength were calculated from the stoichiometric material balances of chemicals in the precipitation reaction. The activity coefficients of ions were also calculated by the modified Debye-Huckel equation. Within the experimental range of oxalate ion activity 1 X 10-8 M to 1 X 10 -5 M, solubility products Ksp and equilibrium constants β1 for rare earth oxalates were obtained.
Electrochemical Characteristics According to the Insertion Behavior of Lithium Ion into Layered Lithium Titanate Whisker
이철태 ; 이진식 ;
Journal of Korean Society for Atmospheric Environment, volume 4, issue 4, 1998, Pages 285~285
Layered lithium titanate whisker, LixTi4O9 , was prepared by a host-guest reaction [l]. Lithium insertion into the layered lithium titanate whisker was investigated to test the feasibility of its application as an active material for a rechargeable lithium cell. The charge and discharge cycle performances of Li/LixTi4O9 were measured between 3.0 V and 0.5 V with 0.25 mA/㎠. Using 1 M LiC1O4 in propylene carbonate(PC) as the electrolyte, the initial discharge capacity of 130 mAh/g was obtained at a plateau region of 1.2V. For the first 20 cycles, the discharge capacity obtained was between 80∼100 mAh/g, then decayed to 60∼80 mAh/g due to a defect in spinel oxides Li4Ti5O12.
The Morphology of Silica Supported MoO₃Catalysts
Journal of Korean Society for Atmospheric Environment, volume 4, issue 4, 1998, Pages 290~290
The morphology of silica supported MoO3 catalysts, which was prepared by impregnation of ammonium heptamolybdate with various weight loadings up to 35 wt %, was studied using X-ray diffraction. In addition to the orthorhombic phase, the behavior of the rarely studied hexagonal phase was characterized. All morphologies of silica supported MoO3 appear to be thermodynamically driven. For highly loaded catalysts there appeared three states : a metastable sintered hexagonal state, a well-dispersed hexagonal state at a moderate temperature (300℃), and the sintered orthorhombic state at a high temperature (500℃). Whereas the sintered orthorhombic phase is detected by using XRD at loadings in excess of 1.1 atom Mo/nm2, the well-dispersed hexagonal phase is not detected even until 4.0 atoms Mo/nm2. It is possible to produce the well dispersed hexagonal phase from the sintered orthorhombic phase with an ammonia impregnation and subsequent calcination at 300℃. The higher apparent dispersion of the hexagonal phase may arise from some role of ammonia which results in a stronger MoO3- SiO2 surface interaction.
Adsorption Equilibria of Light Hydrocarbon-Carbon Dioxide Mixtures on Zeolite 5A Using the Two-Dimensional Equations of State
이병철 ; 조찬휘 ;
Journal of Korean Society for Atmospheric Environment, volume 4, issue 4, 1998, Pages 298~298
Accurate description of adsorption equilibria of gases on adsorbents is essentially required in the design of gas adsorption separation processes. The equilibrium isotherms were measured using the conventional volumetric method for the adsorption of pure light hydrocarbon gases (methane, ethane and propane) and their mixtures with carbon dioxide on zeolite 5A at 273.2, 303.2 and 323.2 K. Various forms of the two-dimensional equations of state (2-D EOS) were used to describe the adsorption equilibria between the adsorbed and gas phases. Model constants for the 2-D EOS were evaluated for each pure component and binary mixture system, respectively, by correlating with the experimental data. Extensive statistical analyses were performed for calculations of pure component and binary mixture isotherms. The 2-D EOS models were found to be capable of fairly representing adsorption equilibria.
Characterization of Dealuminated NiY Zeolite and Catalytic Activity for Ethylene Dimerization
손종락 ; 박준호 ;
Journal of Korean Society for Atmospheric Environment, volume 4, issue 4, 1998, Pages 308~308
A series of dealuminated NiDY zeolites were prepared by the reaction of NH4NaY with SiC14 at elevated temperatures followed by exchanging with NiC12 solution. The acid strength and thermal stability of dealuminated zeolite samples increased with the degree of dealumination. Upon dealumination up to Si/Al ratios of 6.0, the increases of catalytic activities for ethylene dimerization were correlated to the OH stretching band shifts in infrared spectra and to the increase of acid strength for the dealuminated NiDY samples. It is suggested that Ni+ ions take part in the formation of the catalytically active sites.
Life Cycle Inventory Analysis of National Electricity Supply System
김성진 ; 권혁규 ; 허탁 ;
Journal of Korean Society for Atmospheric Environment, volume 4, issue 4, 1998, Pages 314~314
The environmental aspects of the electricity supply system in Korea has been analyzed from the point of view of Life Cycle Assessment (LCA). As an initial step, thermal power generation, which has the largest portion in national electricity system and is considered to release significant amounts of emissions, is defined as the system. All the inputs and outputs associated with the defined system has been identified and calculated based on the delivery of 1kWh electricity generated by thermal power to consumers. The national electricity supply system is a circle-network type connecting the whole country to a single super grid with all generators feeding into it and all consumers drawing from it. Thus, the national averaged data have been collected and used to describe the present system. The Life Cycle Inventory Analysis (LCI) results show that anthracite releases the largest amount of airborne emissions and LNG releases the smallest amount of emissions among the fuels used in thermal power generation. The most dominant airborne emissions is CO2 which is one of the main causes for global warming effect. Waterborne emissions like COD, SS, oil etc and solid wastes such as waste synthetic resins and combustion ashes are also quantified. The results of the analysis carried out here will be a part of the basic database for indispensible electricity in LCA studies for almost all industries.
A Facile Preparation of 2,2'-Diphenyl-4,4'-dihydroxybiphenyl - A New Synthetic Route
Journal of Korean Society for Atmospheric Environment, volume 4, issue 4, 1998, Pages 319~319
Nickel(0)-catalyzed homocoupling of aryl mesylate of 4-protected-2-substituted hydroquinone was utilized in the key step of a reaction scheme which leads to the synthesis of 2,2'-diphenyl-4,4'-dihydroxybiphenyl. The new synthetic procedure reported in this paper started from the commercially available 2-phenylphenol as a starting material.
Electroluminescent Properties of Anthracene-Based Dyes with α - and β - Naphthylethenyl Substituent
김홍수 ; Tetsuo Tsutsui ;
Journal of Korean Society for Atmospheric Environment, volume 4, issue 4, 1998, Pages 324~324
New electroluminescent materials based on anthracene chromophore, 9,10-bis( α-naphthylethenyl)anthracene (α-BNA) and 9,10-bis(β-naphthylethenyl)anthracene (β -BNA) were newly synthesized. The anthracene derivatives with bulky substituent possessed high melting point and they gave stable amorphous films through vacuum-sublimation. Two types of electroluminescent devices were fabricated with double layer and triple layer structures : ITO/TPD/emission layer/MgAg, and ITO/TPD/emission layer/OXD-7/MgAg, respectively. In the triple layer devices with the emissive layer of α-BNA and β-BNA, efficient orange electroluminescencc was observed in both types of device : maximum luminance was about 9900 cd m-2 , 10000 cd m-2 at an applied voltage of 10 V and maximum external quantum efficiency in the double layer devices was 0.9%, 1.4%, respectively.
Lewis Acid Catalysts and Solvents Effects on the Alkylation of Naphthalene
김영대 ; 김주희 ; 심상준 ; 우경자 ; 최광진 ; 조영상 ;
Journal of Korean Society for Atmospheric Environment, volume 4, issue 4, 1998, Pages 329~329
The alkylation of naphthalene with 1,2,4,5-tetramethylbenzene was studied using various catalysts and solvents. Among many alkyl halide solvents and Lewis acid catalysts screened, aluminum chloride and dichloromethane were found the most effective catalyst and solvent, respectively. The alkylation activity was enhanced and product distributions were also favorably changed by introducing a small amount of benzylchloride to the base solvent of dichloromethane.
Solvent-phase Thermal Cracking of Lignin for Production of Potential Liquid Fuels
이윤영 ; 이병학 ;
Journal of Korean Society for Atmospheric Environment, volume 4, issue 4, 1998, Pages 334~334
Lignin is the least utilized biomass component. Unlike the ones from pulping process, the lignins generated from the biomass conversion process are relatively clean, free of sulfur or sodium. It is a feedstock very much amenable for further conversion. The primary goal of this research is to broaden the existing data base pertaining to this concept. This study has limited the conversion methodology to non-catalytic thermal cracking in solvent phase without supplementation of hydrogen or hydrogen donor solvent. Two different solvents were employed : acetone and butanol. Although these solvents are miscible with water, they were used as water-free basis. The cracking experiments have been done in externally agitated tubing bomb reactors placed inside a sand-bath. The reaction temperatures were ranged 250∼450 ℃. The overall conversion was determined by the weight of residual solid. The liquid products were analyzed by GC/MS. The overall conversion generally increased with reaction temperature up to 400 ℃ then leveled off thereafter. The highest conversions were observed in the vicinity of 60% for both acetone and butanol cracking. In the case of cracking in acetone phase, hydrocarbons as well as oxygenates were found. The identified primary products included branched alkene (dimethyhexone), aromatics (trimethyl benzene), side-chain oxychemicals (methylpentanone trimethyl-cyclohexanone), ketones (methyl-isobutyl ketone), and phenolics (methyl, ethylphenol). The products from butanol phase cracking included : esters (methyl-propyl, butylesters), ethers (N-butyl, isobutylethers), and phenolics (methoxy, di-butoxy phenols).
Gelatin Modification with Photocuring Thymine Derivative and its Application for Hemostatic Aid
정동준 ; Takehisa Matsuda ;
Journal of Korean Society for Atmospheric Environment, volume 4, issue 4, 1998, Pages 340~340
Gelatin was derivatized with [1-(2-carboxyethyl)thymine)] via coupling reaction with lysinyl amine groups of gelatin in the presence of a water-soluble carbodiimide. Ultraviolet (UV) irradiation on photosensitive thyminated gelatin films resulted in the formation of crosslinked gelatin gels. Degrees of swelling and photocuring depended on the thymine content of gelatin and irradiation time. The crosslinking rate and physical properties of photocured gelatin are controlled by the degree of derivatization and photo-irradiation time. Photocuring of a viscous thyminated gelatin solution coated on a mechanically injured liver surface of rat was demonstrated for possible use as a sealant or hemostatic aid for bleeding during laparoscopic procedures.
Enantioselective Addition of Diethylzinc to Aldehydes Catalyzed by Chiral Hydroxymethylthiazolidines
김상한 ; 정성택 ; 진명종 ;
Journal of Korean Society for Atmospheric Environment, volume 4, issue 4, 1998, Pages 345~345
A series of chiral thiazolidine-based β-amino alcohols 2a-c was readily synthesized from enantiomerically pure L-cysteine ethyl ester hydrochloride. These compounds could be used as chiral catalysts in enantioselective addition of diethylzinc to aldehydes. Particularly, 2c was found to be the most efficient catalyst, which produced optically active secondary alcohols with moderate enantioselectivity (up to 76% ee) in good yield.