Y2-xGdxO3:Eu, phosphors for plasma display panel(PDP), were prepared by Pechini method which use yttriun chloride, gadolinium chloride, and europium oxide as starting materials. This method is a different way to the synthesis of europium(Eu)-doped phosphors, and it consists of the formation of a polymeric resin obtained by polyesterification between metal chelate compounds and a polyfunctional alcohol. This needs lower temperature than solid-state synthetic method. The prepared Y2-xGdxO3:Eu phosphor particles had spherical shape and coherence. The luminescence intensity of Y2-xGdxO3:Eu phosphor particles increased according to the increase of gadolinium(Gd) content(to 0.8mol%), and Y1.2Gd0.8O3:Eu phosphors had the highest luminescence intensity under vacuum ultra violet(VUV) excitation. The optimum concentration of Eu in the phosphor and optimum calcination temperature was 3wt% and 1100℃. The prepared phosphors were consist of particle, and its size was between 100nm and 150nm. Among the different polyfunctional alcohols, diethylene glycol(DEG) improved the luminescence intensities of phosphors more than other additives. The Pechini method proved that it is demonstrated to be suitable for the synthesis of phosphors used in PDP.
To provide an aqueous rust inhibitor for metalworking lubricant having low toxicity and excellent rust resistance, we synthesized diester of malonic acid by three consecutive esterifications with over 98% of conversion. This substituted malonic diester could be used as an additive to mineral oil based metalworking lubricant. These metalworking lubricant compositions were showed excellent rust resistance and suitable for various metals and different metalworking processes including hot rolling and cold rolling of aluminum and aluminum alloys.
The VOCs discharge characteristics of miscellaneous assembly metal manufacture & metal processing industries, in the SihwaㆍBanwol Industrial Complex, were analyzed according to detailed categories per industry, as based on the Korea Standard Industrial Classification, by comparing the conditions before and after the installation of process and prevention facilities. The average concentration of benzene was highest in the metal heat treatment industry (28921) whereas that of toluene was highest in the painting & membrane treatment industry (28923). In addition, with respect to prevention facilities, our evaluation proved that the decreased efficiency was worse for the discharge facilities of pollutants from the plating industry (28922) and painting & miscellaneous membrane treatment industry (28923), with some exceptions, while most facilities showed no decreased efficiency. Therefore, it is believed that an accurate survey of the conditions of administration/operation facilities will need to be conducted, and the decreased efficiency will also need to be evaluated so that adequate prevention facilities can be reviewed and selected.
The purpose of this study is to propose guidelines for introducing the JIT(Just-In-Time) purchasing to enhance the competitiveness of Korean manufacturing companies. This study employed an extensive survey on the use of the JIT purchasing systems among
The purpose of this study is to explore the correspondence level to product Liability in the enterprises. The results of this study are to offer basic information for a planned manufacturing system for safety products. Especially important things are build up the foundation of system and abide by it for safety products. The producer and supplier(distributors) of the products should satisfy the increasing consumer safety needs. This survey show us that manufacturing the safety products is important factors for korean enterprise management. But, in the reverse, neglect to take appropriate measures promptly.
Spherical Ag powder was prepared in the system of by wet chemical reduction method. The size of Ag powder was increased as the reaction temperature and the concentration of reducing agent was decreased in the constant concentration of dispersion agent. Optimum conditions of producing Ag powder having of D50 was 1M of , 0.5M of , 1.5g of Gelatine in the room temperature.
[ ] oxide layer on the surface of each W(tungsten) nanopowder produced by the electric explosion of wire(EEW) process were formed during the 1vol.% air passivation process. The oxide layer hindered sintering densification of compacts during SPS process. The oxide phase was reduced to the pure W phase during SPS. The W nanopowder's compacts treated by the hydrogen reduction showed high sintered density of 94.5%. after SPS process at .
This study was to investigate the effect of the addition of red ginseng powder in Dasik. The addition of red ginseng powder in Dasik that we used with was in the ratio of 0%, 2%, 4%, 6% and 8% of red ginseng powder to Dasik in weight. Also, we used two different kinds of Dasik. One was made of starch and the other was made of flour. The physic-chemical analysis and sensory test were performed on the Dasik. The red ginseng powder added flour and starch Dasik showed lower moisture content and higher ash content compared with the non-added control group. In color analysis, whereas L value lowed at the addition of red ginseng powder, a and b value increased at the addition of red ginseng powder. In mechanical texture test, addition of red ginseng powder starch Dasik showed high hardness, cohesiveness and brittleness. Addition of red ginseng powder flour Dasik showed high springiness and gumminess. In the sensory test, the addition of the red ginseng powder reduced the sweetness and increased the surface color and the flavor. There was no difference in preference between the Dasik with up to 4% of red ginseng powder added and the control group, but the Dasik with 6% or more red ginseng was found undesirable (p<0.05). In conclusion, the Dasik with up to 4% addition of red ginseng powder would be the useful method to fulfill the traditional quality of Dasik. It was also found that the flour Dasik was to be more preferable than the starch Dasik.
Acrylic adhesives for automobiles protection were prepared by emulsion polymerization. Monomers used were n-butyl acrylate(BA), acrylonitrile (AN), butyl methacrylate(BMA), glycidyl methacrylate(GMA), and acrylic acid (AA). Emulsifiers used were sodium lauryl sulfate and polyoxyethylene lauryl ether, which are an anionic emulsifier and a nonionic emulsifier respectively. Potassium persulfate was used as an initiator and polyvinyl alcohol was used as a stabilizer. Emulsion polymerization was carried out in a semi-batch reactor at 70℃ and agitation speed was kept at 200 rpm. Water resistance, heat resistance, acid resistance, alkali resistance and smoke resistance were examined. As a result, when each 0.03 mole of GMA and AA was introduced, the adhesion properties and various above mentioned resistances of the prepared adhesives were satisfied the standard for automobiles.