Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of Korean Society for Atmospheric Environment
Journal Basic Information
Journal DOI :
Korean Society for Atmospheric Environment
Editor in Chief :
Volume & Issues
Volume 13, Issue 6 - Dec 1997
Volume 13, Issue 5 - Oct 1997
Volume 13, Issue 4 - Aug 1997
Volume 13, Issue 3 - Jun 1997
Volume 13, Issue 2 - Apr 1997
Volume 13, Issue 1 - Feb 1997
Volume 3, Issue 4 - 00 1997
Volume 3, Issue 3 - 00 1997
Selecting the target year
Preparation and Dielectric Properties of Ferroelectric Barium Titanate Fine Particles by Hydrothermal Method
엄명헌 ; 이철태 ; Hidehiro Kumazawa ;
Journal of Korean Society for Atmospheric Environment, volume 3, issue 4, 1997, Pages 251~251
BaTiO3 fine particles with perovskite structure were synthesized using amorphous TiO2 at temperatures as low as 300℃ by hydrothermal method. Barium hydroxide and titanium tetraethoxide were used as starting materials. The relationship between the specific dielectric constant of sintered disks and the mean size of synthesized particles has been investigated. The mean size of the BaTiO3 particles synthesized by hydrothermal reaction for 4 hours was nearly 0.047㎛ while the barium-to-titanium (BT) molar ratio≥ 1.2. The specific dielectric constants of sintered BaTiO3 disks exceeded 6000 with the particle size of 0.10-0.17㎛. It was speculated that the particle size of resulting disks would considerably affect the specific dielectric constant of resulting disks.
The Influence of Scrap Poly(vinyl butyral) Film on the Morphology and Mechanical Properties of Nylon 6 Toughened with SEBS-g-MA
차윤종 ; 이창희 ; 최순자 ;
Journal of Korean Society for Atmospheric Environment, volume 3, issue 4, 1997, Pages 257~257
In order to replace the role of maleated [styrene-block-(ethylene-co-butylene)-block-styrene](SEBS-g-MA) triblock copolymer by the recycled poly(vinyl butyral)(PVB) film as a toughening agent or an impact modifier, the influence of scrap PVB film on the phase morphology and mechanical properties of the binary nylon 6/SEBS-g-MA blends has been investigated. In Nylon 6 with 20 wt% PVB film, the PVB particles are dispersed in the Nylon 6 matrix as spherical particles of which the size is approximately 1.5 ㎛ in diameter. For the tertiary Nylon 6/SEBS-g-MA/PVB blends, under the fixed content of SEBS-g-MA or PVB at the most 20 wt%, the dispersed Particles increased with the PVB content. In particular, 12.5 wt% PVB influences the particle size and the phase morphology of the tertiary blends. Although the tertiary blends have lower impact strength than the binary Nylon 6/SEBS-g-MA blends, the impact strength is still much higher than that of Nylon 6 homopolymer. Thus, recycled PVB film is economically useful as a toughening agent or an impact modifier by partially replacing the role of SEBS-g-MA in Nylon 6 matrix.
Prediction of the Droplet Size of Nonionic Urethane Acrylate Emulsions
박종헌 ; 박노형 ; 최성재 ; 서경도 ;
Journal of Korean Society for Atmospheric Environment, volume 3, issue 4, 1997, Pages 263~263
To predict emulsion droplet size of PEG-modified urethane acrylate (PMUA) which are emulsified in the absence of surfactants, when the steric repulsive potential is dominant, simulation methods and various equations of steric hindrance of nonionic surfactants were used. Lennard-Jones potential was used to describe the interactions of hydrophilic-hydrophilic, hydrophilic-hydrophobic, and hydrophobic-hydrophobic and the movements of chains. Various equations for description of the steric hindrance of polyoxyethylene chains are also used as correction parameters of interaction between other droplets. The results of simulations were relatively similar to those of measured. Most of correction parameters were determined by experiments, and several parameters were treated as variables.
Effect of Fluorine Type Liquid Crystal on Electro-Optical Switching Hysteresis for (Polymer/Liquid Crystal) Composite Films
정환경 ; 정노희 ; Hirotsugu Kikuchi ; Tisato Kajiyama ;
Journal of Korean Society for Atmospheric Environment, volume 3, issue 4, 1997, Pages 269~269
Fluorine type low molecular weight liquid crystal(LC) dependence of the hysteresis of electro-optical switching and the phase-separated structure was investigated for the (polymer/LC) composite film cast from a uniform solution. It is confirmed from morphological observation by scanning electron microscopy (SEM) that the LC domain size of the composite film containing fluorine type LCs remarkably decreased. The interfacial phase-mixing behavior between polymer and LC components was evaluated by the time domain method based on the dielectric composite model of the (polymer/LC) composite film, the temperature dependence of the composite film and the atomic force microscopy (AFM). The hysteresis of electro-optical switching for the composite film was strongly dependent on the LC type. When the polymer and the LC were not compatible such as (Poly(methyl methacrylate)(PMMA)/fluorine type LC) composite system, the static hysteresis of the electro-optical switching for the composite film was not observed. It is found that the phase-mixing at the polymer-LC interface upon applying an a.c. electric field had great effect on the electro-optical switching hysteresis of the composite film
Synthesis and Thermal Properties of Thermotropic Liquid-Crystalline Para-type Copolyurethane
이종백 ; 최대웅 ; 이동진 ;
Journal of Korean Society for Atmospheric Environment, volume 3, issue 4, 1997, Pages 277~277
Thermotropic liquid-crystalline copolyurethanes were synthesized by the polyaddition reaction of para-type 2,5-tolylene diisocyanate (2,5-TDI) with 4,4'-bis(ω-hydroxyalkoxy)biphenyls (PUmnT; m and n : carbon number in alkoxy moiety). All PU68Ts and PU611Ts as well as individual copolyurethanes were monotropic liquid crystals showing liquid crystallinity on the cooling state under shear. For example, PU611T(50/50) with [η]=0.77 dL/g exhibited an anisotropic phase from 157 to 137℃. Thermal behavior, was investigated by using differential scanning calorimetry (DSC), polarizing microscopy, X-ray diffraction, and thermogravimetric analysis.
Syntheses and Physical Properties of Two-Component Polyurethane Coatings Using Bromine-Containing Aromatic Modified Polyesters
박홍수 ; 우종표 ; 김한구 ;
Journal of Korean Society for Atmospheric Environment, volume 3, issue 4, 1997, Pages 282~282
Bromine-containing aromatic modified polyester polyols were synthesized by two-step condensation reactions. Intermediate was synthesized by the esterification of m-bromobenzoic acid with trimethylolpropane in the first step. Polycondensation of the intermediate, 1,4-butanediol, and trimethylolpropane with adipic acid was carried out. Two-component polyurethane coatings were prepared by blending these modified polyester polyols and polyisocyanate. Physical properties of these new coatings were found comparable to non-bromine containing coatings, showing rapid drying character and 18 hours of pot-life. The modified coatings with 30wt% m-bromobenzoic acid also showed a self-extinguishing property
Synthesis of Borazine and Its Polymer-Derived Boron Nitride
문교태 ; 민동수 ; 김동표 ;
Journal of Korean Society for Atmospheric Environment, volume 3, issue 4, 1997, Pages 288~288
The study of borazine has been limited due to the cost of raw materials and the reaction apparatus in addition to the low yield less than 30%. Pure borazine has been synthesity by using inexpensive raw materials(NaBH4 and (NH4)2SO4) and simple glass reaction apparatus with much improved yield over 50%. The synthesized borazine and its polymerized product are characterized by IR, ¹H-NMR and TGA/DSC, then compared to commercial products. It was, finally, confirmed that the borazine polymer was converted to a pure boron nitride(h-BN) on heating to 1500℃ with 75% ceramic yield.
Decomposition and Conversion of Carbon Dioxide Into Synthesis Gas Using Thermal Plasma
윤상흥 ; 김건중 ; 박동화 ;
Journal of Korean Society for Atmospheric Environment, volume 3, issue 4, 1997, Pages 293~293
The thermodynamic equilibrium calculations of the direct decomposition of CO2, the reaction of CO2 with CH4, the reaction of CO2 with a mixture of CH4 and O2, and the reaction of CO2 with H2 were performed in the temperature range of 500k ∼6,000K at atmospheric pressure. The direct decomposition of CO2, the reaction of CO2 with CH4, the reaction of CO2 with a mixtureof Ch4 and O2 and the reaction of CO2 with H2 were studied using thermal plasma as a heating process and a water-cooled tube as a quenching process. The typical plasma power was 4.8kW at atmospheric pressure. The conversion into carbon monoxide of the direct decomposition of carbon dioxide was found less than 11%. The conversion of the reaction of carbon dioxide with reactant gas(CH4 or H2) was much higher than the conversion of the direct decomposition of carbon dioxide. The effects of CH4 on the conversion of CO2 are better than the effects of H2. The maximum conversion obtained in this work was 89%.
Dynamic Mechanical Investigations into Particle/Particle Interfaces in Reactive Latex Films
박영준 ; 김정현 ;
Journal of Korean Society for Atmospheric Environment, volume 3, issue 4, 1997, Pages 298~298
The average diffusion coefficient D of polymer chains across particle interfaces having different surface functionality was obtained from dynamic mechanical analysis to compare the results of the rate of tensile strength development. The rate of tensile strength development was decreased with increasing surface functionality of reactive latexes. This indicated that the interpaticular crosslinking reaction restricted the interdiffusion of polymer chains during film formation and annealing process.
AFM Study of Morphological Rearrangement of Poly(butyl methacrylate) Latex in the Presence of Alkali Soluble Resin
박영준 ; 김정현 ;
Journal of Korean Society for Atmospheric Environment, volume 3, issue 4, 1997, Pages 305~305
Atomic force microscopy was used to analyze the surface morphology of PBMA latex containing alkali soluble resin (ASR) for comparison in the difference of surface structure and topography. It was shown that the more instances of disruption to regular packing of particles were observed in latex film containing ASR. As the annealing proceeds, PBMA latexes are more susceptible to fusion than some of the adsorbed ASR at the particle surface or existed on the top layer. The difference of degree of fusion between two phases would be bigger at higher temperature, thus it leads to deeper and wider dent on the particle surface.
Rigorous Analysis for Design and Performance of the Water/Hydrogen Isotopic Exchange Column in a Tritium Removal Facility
김광락 ; 안도희 ; 이한수 ; 백승우 ; 정홍석 ;
Journal of Korean Society for Atmospheric Environment, volume 3, issue 4, 1997, Pages 310~310
A rigorous calculation for the analysis of a water/hydrogen isotopic exchange column packed with a wet-proofed catalyst was carried out from the model equations, composed of a material balance and equilibrium relationships on the scrubbing and catalyst bed. The solutions were determined out by using a successive iteration procedure and the parametric investigations were simulated for the effect of design and operating variables on the hydrogen isotopic composition within the column. It was observed that the maximum detritiation performance was obtained at the temperature condition giving an equi-molar composition ratio of the water vapor to the given hydrogen stream in the column. The optimum operating temperature should be chosen at the larger detritiation conditions giving a reasonable processing flow rate. In addition, this model was found to be useful for checking the column performance during operations.
Detection of Feedpipe Backmixing by Conductivity Technique
조명찬 ; 노병일 ; 김종현 ; 신춘환 ;
Journal of Korean Society for Atmospheric Environment, volume 3, issue 4, 1997, Pages 318~318
Feedpipe backmixing in an agitated vessel could be detected successfully using a newly developed conductivity technique. The idea of this technique is to use the difference in the conductivity between tap water in the feedpipe and NaCl solution in the vessel. When the vessel fluid penetrates into the feedpipe due to high agitator speed, the conductivity around the electrodes in the feedpipe is increased. The change in the conductivity was sensed by the electrodes and the resultant output signal was recorded by a pen-chart recorder. In order to get maximum sensitivity in detecting the conductivity change, an electric circuit was modeled by considering current-voltage relations of the circuit. When the minimum measurable peak occurred on the recorder by feedpipe backmixing, the NaCl concentration change around the electrodes was on the order of 10-5mole/1. Compared to the 40 mmo1/1 concentration of NaCl in the vessel, this resolution was comparable to the 1,000 times dilution of the vessel concentration.
A Study of the Stereodirecting Effect by an Allylic Nitrogen Substituent on Dihydroxylation Reactions of Cyclic Double Bonds
오준석 ; 홍유성 ; 김영규 ;
Journal of Korean Society for Atmospheric Environment, volume 3, issue 4, 1997, Pages 326~326
Stereoselective introduction of a vicinal amino alcohol group is an essential step for the preparation of biologically active natural products such as the side chain of Taxol, an anticancer agent, and phytosphingosine, one of the important cell membrane components. The goal can be efficiently achieved by the osmium-catalyzed dihydroxylation reaction of chiral allylic amines that are easily prepared from readily dvailable α-amino acids. In order to understand the stereodirecting effect by an allylic amino substitutent, diastereoselectivity in dihydroxylation reactions of 1-aminosubstituted 2-cyclohexenes using osmium tetroxide (OsO4) was systematically investigated in various solvents for the first time. A good to excellent anti selectivity (from 10:1 to >20:1) was obtained with an azido substituent (3-azidocyclohexene), which did not show dependence on solvent polarity. No significant change in the diastereofacial selectivity was also noted by changing the water content in THF. However, the facial selectivity for the anti isomer in monoprotected N-Boc amines decreased with a decrease in the solvent polarity. The best selectivity (5.9:1) for the anti diol isomer was produced in DMF and no selectivity in CH2Cl2. Cyclohexenes with diprotected allylic amines did always show the exclusive anti selectivity irrespective of the solvent polarity. Dependence of diastereoselectivity by the monoprotected amino susbstitutents on the solvent polarity could be attributed to the hydrogen bonding effect. The steric effect appears to be responsible for the exclusive selectivity in N,N-disubstituted amino cyclohexenes.
Simulation of Sorption and Dynamic Behaviors of Cyclohexane in Silicalite
이종명 ; 안병준 ;
Journal of Korean Society for Atmospheric Environment, volume 3, issue 4, 1997, Pages 335~335
Simulation of sorption and transport of cyclohexane in the silicalite zeolite have been carried out using CERIUS2 package. The result shows that four cyclohexane molecules can be adsorbed in every unit cell of the zeolite and all cyclohexanes are located in channel intersections of the zeolite, as compared this results to the experimental results determined by volumetric method. Diffusional transport of cyclohexane is found to strongly depend on the shape as well as the size of the zeolite pore.