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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 9, Issue 4 - Dec 1993
Volume 9, Issue 3 - Sep 1993
Volume 9, Issue 2 - Jun 1993
Volume 9, Issue 1 - Mar 1993
Volume 9, Issue E - 00 1993
Selecting the target year
Rapidity of Recent Global Warming : What Factors are Important\ulcorner
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 1~10
A brief description on the greenhouse gases, the greenhoue effect, sea level changes, forcing of climate, the history of Earth's changing climate based on the IPCC REPORT and the records of the recent variation of the climate in the Republic of Kore is presented here for help enhancing awareness of the issues. The climate of the Earth has the potential to be changed on all timescales by the fluctuations of the concentrations of radioactively active greenhouse gases, solar radiation, aerosols and albedo. However, the rate of the recent global warming seems to be larger and rapid than any have occurred thorughout recorded history enough to draw the world-wide attention and worry concerned with the theme of environment and development. There are still uncertainties in the predictions relating to the timing, magnitude and the pattern of the climatic change due to the current incomplete understanding of various aspects of the complex processes. Nonetheless, the scientific results avaliable is sufficient to allow for decisive precautionary measures to be taken.
The Micro- Total Analytical System for the Detection of Bacteria/Viruses
민준홍 ; Antje Baeumner ;
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 1~1
Gene-based biosensors have allowed fast and specific detection of pathogenic bacteria and viruses in past decade. In addition to nucleic acid biosensors, DNA arrays or gene have been researched to detect sequence-specific information in a faster, simpler and cheaper manner or the micro-total analytical system (μ-TAS), also known as "Lab-on-a-Chip", not only incorporates detection but additionally sample preparation and a digital readout all in one device. A variety of fields have to be combined to realize these micro-total analysis systems. Thus, several biological, chemical and engineering techniques are introduced in this paper to develop μ-TAS for the detection of viruses and bacteria.
Protein Microarrays and Chips
이상엽 ; 이석재 ; 정희태 ;
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 9~9
Recent development of protein microarrays and protein chips is allowing high-throughput analysis of proteins and/or molecules interacting with proteins. Powerful new technologies have currently been reported, which range from synthetic peptide arrays to whole cell protein arrays. Protein chips have been used in various applications for detecting interactions between enzyme-substrate, synthetic molecules-protein and different kinds of protein-protein. Such studies demonstrated that protein chips can be used to examine the functions of thousands of proteins in parallel in a single experiment. This review describes the development of protein microarrays and their potential applications in biological research, medicine and diagnostics.
The Effect on the Terrestrial Ecosystem by the Air Pollution and Acid Rain
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 11~18
Nano- and Microscale Friction Behaviors of Functionalized Self-Assembled Monolayers
박상권 ; 김용욱 ; 임종주 ; 안효석 ; 박상준 ;
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 16~16
The nano- and microscale friction behaviors of self-assembled monolayers (SAMs) of ω-functional n-alkanethiol surfactants were investigated in order to provide fundamental information regarding the effect of molecular structure of boundary lubricant on its lubrication performance. The SAMs with different terminal group and hydrocarbon chain length were prepared on gold substrates and atomic force microscopy tips by chemical adsorption and characterized by contact angle and X-ray photoeletron spectroscopy (XPS) measurements. The nano- and microscale friction coefficients of the SAMs were measured by a lateral force microscopy (LFM) and an oscillating friction and wear tester, respectively. As results, it is found that both the nano- and microscale friction behaviors were significantly affected by the terminal functionality and the hydrocarbon chain length of the SAMs. In addition, the nano- and microscale friction behaviors showed similar trends of the molecular structure effects.
A Review on Basic Concepts for Clean Technology
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 19~24
Hippocampal Neuronal Network Directed Geometrically by Sub-Patterns of Microcontact Printing (μCP)
안동준 ; 진종주 ; 이길선 ; 권광민 ; James Jungho Pak ; 김진희 ; Lee, Kyoung J. ;
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 25~25
The control of neuronal cell adhesion and growth in artificially defined networks in vitro was developed for the study of neuronal signals propagation. Microcontact printing (μCP) with PDMS microstamps was used as the chemical method to control cell adhesion and growth into defined networks. For controlled hippocampal neuronal cell growth, cytophilic poly-d-lysine (PDL) was patterned on glass substrates by μCP and then cytophobic PEG was self-assembled for passivation. The patterns were identified by fluorescent microscopy, atomic force microscopy, and condensation figure. The positively charged surface of PDL patterns interacted electrostatically with the negatively charged moieties of the cell membrane surfaces so that the attachment of the cells to the substrate surface was enhanced. The cultured hippocampus cells grew quite selectively along the printed PDL tracks. The track width suitable for forming single neuronal growth was discovered to be less than about 10 μm.
Recent Technologies for Control of
Emission from Stationary Sources
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 25~32
Fractal Memory Function of Biomolecular Photodiode Consisting of Ferrocene/Flavin/Viologen/Cyochrome c Hetero-Film
최정우 ; 남윤석 ; 조경상 ; 이원홍 ; 박수용 ; Masamichi Fujihira ;
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 31~31
A fractal memory function in the nanoscale biomolecular electronic device was investigated. Four functional molecules, cytochrome c, viologen, flavin, and ferrocene, were used as the electron acceptor, the relay, the sensitizer, and the electron donor, respectively. The hetero- Langmuir- Blodgett (LB) films were fabricated by sequential deposition of ferrocene, flavin, and viologen onto substrate. The cytochrome c-adsorbed hetero-films were prepared by the adsorption of cytochrome c onto hetero-LB films due to the electrostatic force. As the biomolecular photodiode, a metal/insulator/metal (MIM) structured electronic device was fabricated by the deposition of the aluminum onto the hetero-film. The transient photocurrent of the biomolecular photodiode was measured and the decay time constant was calculated as -0.146. The experiment and simulation of the response to the pulse train inputs corresponding to different ASCII codes were performed with the decay time constant, and the fractal memory effect of biomolecular photodiode was verified.
A Perspective on Indoor Air Pollution
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 33~43
Amphiphilic Polyurethane-co-polystyrene Network Films Containing Silver Nanoparticles
김주영 ; 신동현 ; 인교진 ; 서경도 ;
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 37~37
Yellow transparent polyurethane-co-polystyrene films containing silver nanoparticles could be synthesized. Silver nanoparticles and transparent polymer film making up nanocomposite films were formed simultaneously through radical initiated polymerization of amphiphilic urethane acrylate, nonionomer (UAN)/styrene/silver nitrate mixtures. Size of silver nanoparticle could be controlled by varying weight ratio of styrene in UAN/styrene mixtures and chain length of PEO and PPO segment in UAN chain, which are much easier process compared to the synthetic process of nanoparticles using amphiphilic block copolymers. Formation of silver nanoparticles and change of nanoparticle size could be conformed by transmission electron microscopy and characteristic UV absorbance spectra. Tensile modulus and glass transition temperature of polyurethane-co-polystyrene films were drastically increased at 0.45 wt% of silver nanoparticles embedded at their matrix, indicating that silver nanoparticles embedded at polymer films can act as an inorganic nanofiller for improving mechanical property.
Quantitative Source Estimation of Particulate Matters in Suwon Area Using the Target Transformation Factor Analysis Based on Size Segregation Scheme
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 44~50
The suspended particulate matters had been collected by a cascade impactor having 9 size fragnated stages for 2 years (Dec. 1989 to Nov. 1991) in Kyung Hee University-Suwon Campus. The particulate matters were then collected on each stage by membrane filters. The weight concentration on each stage was estimated by a microbalance and further chemical element concentrations were determined by an XRF system. The study focused on developing of a receptor model using the TTFA (target transformation factor analysis) to apportion aerosol mass with the 30 ambient data sets. Each data set consists of the 8 size-ranged subdata sets characterized by 13 element variables. Even though a couple of sources could not be identified, three to five sources were extracted from each aerosol size-range, and then 9 statistical source profiles were generated. Finally, source contribution of particulate matters on each size-range could be estimated in Suwon area.
Self-Association between Nano-sized Bilayer and Amphiphilic Polymer
강상윤 ; 박문기 ; 정희태 ;
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 45~45
The membrane bending elastic modulus and microstructure were estimated for the vesicles with and without the addition of polymer-surfactant macromolecules by cryogenic transmission electron microscopy (cryo-TEM) and small angle neutron scattering (SANS). The mixture of cetyltrimethylammonium tosylate (CTAT) and sodium dodecylbenzensulfonate (SDBS) self-assembles into vesicle phase. In order to examine the effect of polymer addition, Poly (ethylene glycol)-dimyristoylphosphatidylethanolamine is used as the component of added macromolecule. The bilayer bending rigidity is evaluated as 0.5 kBT from the size distribution obtained by the image analysis of cryo-TEM regardless of polymer addition. However, it is observed from SANS curves that the width of size distribution is reduced as the amount of polymer is increased because of enhanced bilayer asymmetry after polymer's penetration into membrane. Therefore the mechanism of incorporating polymer into bilayer is understood as that the hydrophobic part of polymer is anchored into the membrane of vesicle following the adsorption onto the surface of vesicle from the aqueous phase.
Dispersion Quality and Rheological Property of Polymer/Clay Nanocomposites: Ultrasonification Effect
임성택 ; 최형진 ; Myung S Jhon ;
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 51~51
Ultrasonication was used to control the dispersibility of organophillic montmorillonite (OMMT) and the rheological properties of poly(ethylene oxide) (PEO)/OMMT nanocomposites, which were prepared via the solvent casting method using chloroform as a cosolvent. X-ray diffraction analysis showed that the application of ultrasound to OMMT dispersions prior to the mixing with polymer solution increases the layer spacing in clay particles. We systematically developed the ultrasonification preparation procedure by establishing the relationship between dispersion quality and rheological properties of polymer/clay nanocomposites. Dispersion quality was compared with both thermal properties obtained from TGA and rheological properties measured in steady shear and dynamic oscillatory tests. To analyze the non-Newtonian flow behavior, we analyzed shear viscosity data via the Carreau model. We found that the steady shear viscosity and power-law index increase with the dispersion quality for a fixed OMMT content. The microstructure of PEO/OMMT nanocomposite having enhanced dispersibility through sonication was also examined using transmission electron microscopy.
On Air Pollution and Visibility Reduction in Seoul
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 51~60
In order to study on the cause of visibility aggravation, we have selected the days of low-visibility observed in Seoul with haziness that was below 6km from 12 to 15 LST. According to the examinations, the number of low-visibility days satisfying the criteria is 30 days in 1989, 39 days in 1990, and 35 days in 1991, respectively. The annual number of low visibility days appears to increase mainly due to an increase in emission of air pollutants and in anthropogenic water vapor in the biosphere. The relationship between visibility and air pollutants(TSP, $NO_2, SO_2, O_3$) of selected days is also studied. Air pollution concentrations of selected days are much higher than those of other days. It is observed that the cause of visibility aggravation in Seoul is mainly smog and air pollutants. In particular, the visibility reduction and high $SO_2$ concentrations at Seoul in winter are similar phenomena that occurring with London smog, while the visibility reduction and high $O_3$ concentrations at Seoul in summer are also similar to the type of Los Angeles smog.
Synthesis and LCST Behavior of Thermosensitive Poly (N-isopropylacrylamide)-Clay Nanocomposites
설길수 ; 류성규 ; 장진해 ;
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 58~58
Thermosensitive polymer-clay nanocomposites were prepared via organically modified claypoly(N-isopropylacrylamide) (PNIPAM) nanocomposites. Nanocomposites containing a 5 wt% of montmorillonite exhibited a lower critical solution temperature (LCST) similar to the unmodified PNIPAM hydrogel, and similar phenomena with a large thermal volumetric change and transition kinetics compared to conventional PNIPAM gels. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) suggested that the clay minerals in the nanocomposite were partially exfoliated in a dried state and mostly exfoliated in a swollen state.
On the background levels of
observed at Tae-ahn Peninsula in Korea during 1990-1992
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 61~68
Since November 1990, the observations of carbon dioxide$(CO_2)$ levels have been carried out at Tae-ahn Peninsula(TAP) in Korea. Analysis on atmospheric data obtained in the period from November 1990 to August 1992 is carried out and the results are included in this study. It is observed that variations of monthly average level on $CO_2$ are in the range of 315.72 $\sim$ 365.37ppm(amplitude 17.65ppm). The seasonal variation is large with a maximum occurring in March-April and with a minimum in July-August. A comparison of TAP data is made with data obtained at Ryori in Japan for 1991. The annual average value of TAP is 1.79ppm higher than that of Ryori. It is also found that in summer the minimum level of $CO_2$ at TAP is almost same as the $CO_2$ level occurring at Quinghai Province in China and at Ulaan Uul in Mongolia. Albeit, a maximum concentration of $CO_2$ at TAP is slightly higher than that of the same gas observed at other sites in spring. We interpret that TAP is generally under the influence of airflows coming from China. According to analysis of trajectories and airflows, we find the high values of $CO_2$ when an air flow is originated mainly from China and when an airflow is both of local(Korea) and of China origins. In contrast, when an airflow of maritime origin arrives, a low value of the atmospheric constituent is observed at TAP.
PtRu Nanoparticle Electrocatalysts Prepared by Various Synthetic Methods for Use in Direct Methanol Fuel Cells
이설아 ; 박경원 ; 권부길 ; 성영은 ;
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 63~63
The synthesis and characterization of carbon-supported PtRu nanoparticles were carried out by impregnation and colloidal methods and products were compared with commercial carbon-supported PtRu. To confirm the characteristics of the synthesized PtRu nanoparticles, TEM (and EDX), XRD, and electrochemical analysis were performed to evaluate alloy formation, surface structure, chemical composition of the nanoparticles, and the electrocatalytic activity for methanol oxidation. The impregnation method was relatively easy and straightforward but the average particle size was in excess of 3 nm and the size distribution was broad. However, colloidal methods involved more complicated procedures and required a heat treatment to increase activity, resulting in an average particle size of up to 2.2 - 2.3 mn. The heating conditions used, to achieve a higher catalytic activity, were investigated. A simpler nanoparticle synthetic method that results in a small particle size and high activity without a heat treatment would be desirable.
A Study on the Estimation of Emission Factors and Emission Rates for Motor Vehicles
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 69~77
Exhaust emissions are calculated as a product of the emission factor and the vehicle kilometer traveled(VKT). The emission factor is a function of several parameters such as vehicle model year, vehicle mileage, traffic conditions, etc. The representative driving cycles classified as ten different types of an average vehicle speed were selected by analyzing passenger car driving patterns in Seoul. 51 vehicles were sampled and analyzed by types of vehicles, fuels used, model years and vehicle mileages also, exhaust emissions of them were measured by chassis dynamometer. Regression equations between average vehicle speeds and exhaust emissions are made for the estimation of emission factors at different vehicle speeds. Annual emission rates of air pollutants from motor vehicles in Korea were 1116$\times10^3 ton, 149\times10^3 ton, 413\times10^3 ton and 67\times10^3$ ton for CO, HC, NOx and particulats, respetively in 1990. It was found that 56% of CO and 49% of HC were originated from passenger cars and taxis, in addition, 87% of NOx and 100% of particulates were from buses and trucks using diesel fuels.
Fabrication of Al Nano Powders by Pulsed Wire Evaporation (PWE) Method
이근희 ; 박중학 ; 이창규 ; 김흥회 ;
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 71~71
Nano-sized Al powders were synthesized by the Pulsed Wire Evaporation (PWE) method. The wire, which was fed continuously into a chamber filled with Ar gas, was exploded into nano powders by high pulsed current and voltage. After the nano powders were synthesized, they were classified by sizes using cyclone and various kinds of filters. We passivated the powder surface with a thin oxide layer to stabilize at room temperature. The size and shape of the nano powders were investigated by TEM. XRD was conducted for phase analysis and grain size determination. XPS and BET analyses were conducted for the investigation of the oxide layer on the Al powder and specific surface area, respectively. From the TEM observation, it was found that the Al nano powder was spherical shape of 80 - 120 nm diameter with the thickness of the oxide layer of 2 -3 nm. The Al phase was crystalline with FCC structure, on the other hand the oxide layer was an amorphous state.
pH-Controlled Synthesis of Hierarchically Ordered Ceramics with Wood Cellular Structures by Surfactant-Directed Sol-Gel Procedure
신용순 ; Wang, Li Qiong ; Liu, Jun ; Gregory J. Exarhos ;
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 76~76
Synthesis of hierarchically ordered ceramic materials with wood cellular structures has been developed by an in-situ mineralization of ordered wood cellular structures with surfactant-templated sol-gel solution at different pHs. At low pH, a silicic acid coated onto inner surface of wood cellular structures and kept their structures open to form a positive replica after calcination of wood contents, while at high pH, the precipitating silica particles due to fast condensation clog the empty cellular and pit structures to form a negative replica. The ceramic monoliths after calcinations contain ordered wood cellular structures, multi-layered cell walls, pits, and vessels well-preserved with positive or negative contrasts, respectively. The surfactant-templated mineralization not only helped structural integrity, but also produced hexagonally ordered nanoporosity in the cell walls after calcination.
Studies on the Air Pollution Tolerance of Forma of Hibiscus Syriacus
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 78~80
Of the forma of Hibiscus Syriacus, national flower, a dozens of them have been recommended for landscape treess. To find out the highly resistant forma, 13 forma of Shrub al thea were fumigatedqr with $SO_2$ in phytotron and their visible injury was observed. Visible injury of Shrub al thea forma was spread on the vein in the shape of spot and diffused to whole leaf with wilting. The injury colors of forma were generally dull bluish green, dark grayish green. The tolerant forma to $SO_2$ were Sanchunyeo, Saeachim, Sulag and the highly sensitive forma were Lusi, Youngkwang. Therefore, Sanchunyeo, Saeachim and Sulag were recommeneded to plant in polluted areas.
Measurements of Polycyclic Aromatic Hydrocarbons(PAHs) Concentration in Air of the Seoul Underground Shopping Stores
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 81~92
A purpose of this study was carried out to investigate the concentrations of four elements of PAHs(Polycyclic Aromatic Hydrocarbons) in suspended particulate matters of underground shopping stores in Seoul city. The particulate matters were collected at five underground shopping stores(Yongdungpo, Myongdong, Ulchiro, Express Terminal, Chamshil) in the Seoul area during February-October, 1992. Samples were collected using cascade impactor of low volumn air sampler and were analysed using High Performance Liquid Chromatography(HPLC) with fluorescence detector. Calibration on HPLC analyse is nearly accord with retention time between the standard solution and the samples. Analysed results obtained favorable analysing recovery rate of 97.3% and coefficient of variation of 1.60%. Mean concentrations of suspended particulate matters in five underground shopping stores wre 216.3 g/$m^3$ and observed higher at fine particles(117.2 g/$m^3$) which is respirable particulates than coarse particles(99.2 g/$m^3$). Concentrations of four species PAH were determined with anthracene of 16.8ng/$m^3$, fluoranthene of 72.3ng/$m^3$, benzo(a)pyrene of 0.54ng/$m^3$, and benzo(k)fluoranthene of 0.29ng/$m^3$, respectively. Fluoranthene levels were significantly higher than those levels in other components. PAHs concen-tration at shopping areas showed 21.3ng/$m^3$ in Yongdungpo, 35.1ng/$m^3$ in Myongdong, 23.4ng/$m^3$ in Ulchiro, 11.1ng/$m^3$ in Express Terminal, and 21.4ng/$m^3$ in Chamshil, respectively. Particularly, benzo(a)pyrene and benzo(k)-fluoranthene were detected over 83 percentage in fine particles, while fluoranthene wre highly detected in coarse particles. Also, higher concentrations of benzo(a)pyrene, benzo(k)fluoranthene were found in winter while levels of anthracene and fluoranthene were found higher in summer than other seasons.
Rapid Sonochemical Synthesis of Spherical-shaped Mesoporous SBA-15 silica and Ti-incorporated SBA-15 Silica Materials
이선근 ; 이진우 ; 주진 ; 헌택환 ; 안화승 ; 이호인 ; 이충학 ; 최원용 ;
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 83~83
Mesoporous SBA-15 silica materials were synthesized in short time from one hour ultrasonic irradiation, followed by I ~ 3 h gelation in acidic media. The particle morphology of these sonochemically synthesized mesoporous materials was nearly spherical. Titanium was directly incorporated into SBA-15 silicate framework through sonochemical co-condensation of Ti(O-iPr)4 and Si(OEt)4. The Ti-incorporated SBA-15 silica exhibited good catalytic activity for the oxidation of 2,6-di-tert-butylphenol.
Synthesis of TiO₂Nanoparticles in Reverse Microemulsion and Their Photocatalytic Activity
이만식 ; 이건대 ; 박성수 ; 홍성수 ;
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 89~89
TiO2 nanoparticles were prepared using hydrolysis of titanium tetraisopropoxide (TTIP) in W/O microemulsions consisting of water, nonionic surfactant, and cyclohexane. The physical properties of nanosized TiO2 have been investigated by TEM, XRD, FT-IR, TGA and DTA. In addition, the photocatalytic degradation of p-nitrophenol has been studied by using batch reactor in the presence of UV light in order to compare the photocatalytic activity of prepared nanosized titania. TiO2 particles calcined at 500 ℃ have a stable anatase phase which has no organic surfactants. Above 300 ℃, the product completely transforms into the anatase phase and the rutile phase begins to appear at 600 ℃. The crystallite size and crystallinity increase with an increase of calcination temperature. The particles are shown to have a spherical shape and have an uniform size distribution. In adition, the size of particles increases with an increase of Wo ratio and a decrease of hydrocarbon chain length. In the photocatalytic degradation of p-nitrophenol, the titania calcined at 500 ℃ shows the highest activity on the photocatalytic degradation of p-nitrophenol and the pure anatase structure.
A Study on the Variation of Air Pollutants Emission Rates for Different Traffic Signal System in Metropolitan Area
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 93~100
This study was carried out to investigate the relationship between the traffic signal systmes and the air pollutants emitted by the motor vehicles at Kangnam Intersection. One of the most important measures of effectiveness (MOE) in traffic studies is the delay to vehicles in the system. Delay represents indirect costs to the motorist in terms of time loss and a direct cost in terms of fuel consumption during idling. The results of TRANSYT-7F modeling was correlated among delay, fuel consumption and total travel tiem. Air pollutants emission rate can be calculated by the results of modeling and the Korean type emission factor. As expected the highest emissions, for air pollutants, are observed during the morning rush hours (07 : 00-10 : 00). For better results of modeling, the TRANSYT-7F model needs to modify for the Korean type of traffic model. The results of this study indicate that the variation of air pollutants emission rates were closely related to the traffic signal system.
Nano Pt Particles on TiO₂and Their Effects on Photocatalytic Reactivity
최원용 ; 이재상 ; 김순현 ; 황상만 ; 이명철 ; 이태규 ;
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 96~96
The effects of nano-sized Pt deposits on TiO2 particles on the photocatalytic kinetics and mechanisms for the degradation of ammonia and trichloroacetate (TCA) in water and gaseous CO oxidation were investigated. Although platinization has been a routine method of TiO2 modification, its effects on photocatalytic reaction mechanisms in pollutant degradation need to be fully understood. TiO2 photocatalytic reactions are usually non-selective mainly because of the strong oxidation potential of OH radicals. (1) By using TiO2 deposited with nano-Pt particles, we are able to oxidize NH3 selectively to N2. While the pure TiO2 quantitatively transforms ammonia into nitrite and nitrate, Pt/TiO2 converts NH3 into N2 with reducing the total nitrogen concentration in the suspension. (2) TCA degrades photocatalytically in the presence or absence of dissolved O2, which proposes that two mechanistic pathways (oxic vs. anoxic) are operative. While the anoxic path is not important on naked TiO2, it becomes dominant on platinized TiO2 surface. Therefore, the introduction of dioxygen in aqueous suspension enhances the rate of TCA degradation on naked TiO2 but inhibits it on Pt/TiO2. (3) Platinum deposition on TiO2 greatly enhances the photooxidation rate of CO and the degree of enhancement strongly depends on the kind of TiO2 substrate. Platinized Hombikat TiO2 shows the best activity. The photocatalytic conversion of CO to CO2 is quantitative in the presence Of O2 and no CO2 is generated in the absence of O2.
Separation of Freon-12 and Air Mixture by Adsorption Process
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 101~106
In order to separate the Freon-12 and air mixture$(CF_2Cl_2/Air=0.1/99.9 vol.%)$ by pressure swing adsorption (PSA), the breakthrough curve was experimentally observed in a fixed bed adsorption column. A single adsorber was packed with various adsorbents such as, the activated carbon(S-AC, W-AC) and the molecular sieve(MS-5A, MS-13X). The order of appearance of breakthrough curve is MS-5A > MS-13X > W-AC > S-AC. The activated carbon was found to be more effective adsorbent for separating Freon-12 from the mixture than the molecular sieve was. From the experimental data obtained by the separation of Freon-12 gas out of the air stream in the steady-state PSA process cycle, whose size is the same one of column used for the breakthrough curve observation, it has been confirmed that Freon-rich gas could be obtained from the purge step of PSA and Freon-free air could be obtained from the adsorption step of PSA cycle.
Selective Catalytic Reduction (SCR) of Lean NOx Using Propylene by Plasma Enhanced Catalysis over Nano-Sized Gold Catalyst Supported on Alumina
이대원 ; 류재홍 ; 정동훈 ; 이형상 ; 전광민 ; 이관영 ;
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 102~102
Nano-sized gold catalysts supported on alumina were prepared and applied to the lean DeNOx reaction by plasma-enhanced catalysis. The average size of metallic gold particles estimated by dark field TEM analysis was 4.5 nm. The plasma-Au/Al2O3 system showed an improved DeNOx activity at low temperatures below 250 ℃. In case of plasma-2.0 wt%Au/Al2O3, NOx conversion was about 40% and N2 yield was 10~30% at 100-250 ℃. The NOx reduction activity to N2 using hydrocarbon reductant at this temperature range has not been reported yet. This low-temperature DeNOx activity seems to be caused by the increase of Au - alumina interface due to the formation of nano-sized Au particles, which facilitated plasma-activated NO2 and hydrocarbon being adsorbed on the metallic Au and alumina, respectively, migrated and then reacted with each other.
Yearly Variation and Influencing Factors of Ozone Concentration in the Ambient Air of Seoul
Journal of Korean Society for Atmospheric Environment, volume 9, issue 1, 1993, Pages 107~115
This study was carried out to find the characteristics of surface ozone concentration data obtained during 1988-1991 by the Korea Ministry of Environment. Seasonal data (spring, summer, autumn and winter) wre obtained in May, August, November and February respectively at Kwanghwamun in Seoul. The pollutants analyzed in this study are $SO_2, TSP, CO, NO, NO_2 and NO_2/NO$. Atmospheric factors such as solar radiation, wind speed, relative humidity, cloud amount and atmospheric temperature are also analyzed. The influence of pollutants and atmospheric factors that affect ozone concentration were analyzed by statistical method. The results are summarized as follows : 1. The ozone concentration varied seasonally. The maximum values were 23 ppb in spring, 33 ppb in summer, 16 ppb in autumn and 13 ppb in winter. So the seasonal ozone value was highest in Summer. 2. Te diurnal concentration of ozone was highest during 2-4 P. M. and was very low in the morning and evening. 3. The maximal correlation coefficients of each season between ozone concentration and the influencing pollutants or atmospheric factors asr as follows ; a. spring, r = 0.44(solar radiation) b. summer, r = -0.59(relative humidity) c. autumn, r = -0.55(relative humidity) d. winter, r = -0.58($NO_2$) 4. The major factor affecting the ozone concentration in spring was solar radiation, Relative humidity was the first affecting factor in summer, autumn and $NO_2$ concentration was dominant in winter.