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        검색결과 4,563

        2881.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        BaTiO3, powders were prepared by sol-gel process from different aging time and reaction temperature. Particle shape, size and crystal structure of prepared BaTiO3 powders were analyzed by SEM, XRD and FT-IR. Effect of aging time alternation didn't particularly show up. Spherical nano-sized BaTiO3 powders were obtained from condition more than reaction temperature 55℃, and obtained sintered BaTiO3 powders of tetragonal phase from heat-treatment at 1,100℃.
        4,000원
        2882.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Organic acid salt of fatty polyamide (DDDT) and acrylate of fatty carbamide (DDTCA) were synthesized as a main component for the softener. O/W type non-ionic softener (NSC) was prepared by blending DDDT and DDTCA with beef tallow, lanolin anhydride. polyoxyethylene(7) stearyl ether, and polyoxyethylene(50) oleyl ether. After treatment of NSC to all cotton fabrics, the physical properties such as tear strength, crease recovery, and flexing abrasion resistance were measured. As a result of the measurement, NSC was proved to be durable non-ionic softener with good softness.
        4,000원
        2883.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Synthesis gas is produced commercially by a steam reforming process. However, the process is highly endothermic and energy intensive. Thus, this study was conducted to produce synthesis gas by the partial oxidation of methane to cut down the energy cost. Supported Ni catalysts were prepared by the impregnation method. To examine the activity of the catalysts, a differential fixed bed reactor was used, and the reaction was carried out at 750~850℃ and 1 atm. The fresh and used catalysts were characterized by XRD, XPS, TGA and AAS. The highest catalytic activity was obtained with the 13wt% Ni/MgO catalyst, with which methane conversion was 81%, and H2 and CO selectivities were 94% and 93%, respectively. 13wt% Ni/MgO catalyst showed the best MgNiO2 solid solution state, which can explain the highest catalytic activity of the 13wt% Ni/MgO catalyst.
        4,000원
        2884.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Alkaline powder cleaning agents (APCAs) were prepared by blending of Na2CO3 tetrasodium pyrophosphate (TSPP). sodium orthosilicate (Na-OSi), Na-dioctyl sulfosuccinate (303C), Demol C, and MJU-100A (100A). The physical properties of APCAs tested with steel specimen showed the following results. The cleaning powers of APCA-6 (Na2CO3 250g/TSPP 70g/Na-OSi 40g/303C 60g/Demol C 50g/100A 30g mixture) for press-rust preventing oil was 97% and 98% degreasing at 2wt%, 70℃ and 90℃, respectively; for Quenching oil, the cleaning power of APCA-6 was 95% degreasing at 2wt% and 70℃. From the results, it was ascertained that APCA-6 exhibited a good cleaning power. Also low foaming power tests proved that the APCA-6 maintained good defoaming effect.
        4,000원
        2887.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        nanopowder has been synthesized by means of the flame method using a precursor of titanium tetraisopropoxide (TTIP, Ti. In order to clarify the effect of cooling rate of hot flame on the formation of crystalline phases, the flame was controlled by varying the mixing ratio and the flow rate of gases. Anatase phase was predominantly synthesized under the condition having the steep cooling gradient in flame, while a slow cooling gradient enabled to form almost rutile nanopowder of above 95%
        4,000원
        2888.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The study for producing the flake powders by milling of aluminum foil and gas atomized powders was carried out. The effects of lifter bars on the ball motions and milling of aluminum foils were also investigated. The aluminum foils were laminated each other, elongated, fragmented into small foils and finally formed into the flake powders during the dry ball-milling. The spherical atomized-powders were milled to coarse flake powders with high aspect ratio and then changed to fine flake powders with lower aspect ratio. Even though long times were required for making flake powders by milling of foils, the water covering areas of them were higher than those of powders milled using gas-atomized powders, suggesting aluminum foils were more plastically deformed by micro-forging. On the other hand, as the number of lifter bars increased, the necessary rotation speeds of milling jar for cascading mode and cataracting mode decreased drastically. It was possible to achieve same quality of milled flake powder by using the lifter bars under the lower milling speeds. The painting test showed that the appearance of painted surface was good and optimum content range of aluminum paste in car paint to maximize the degree of gloss was 3-5%.
        4,000원
        2889.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the conventional metallothermic reduction (MR) process for obtaining tantalum powder in batch-type operation. it is difficult to control morphology and location of deposits. On the other hand, a electronically mediated reaction (EMR) process is capable to overcome these difficulties and has a merit of continuous process, but it has the defect that the reduction yield is poor. MR-EMR combination process is a method that is able to overcome demerits of MR and EMR process. In this study, a MR-EMR combination process has been applied to the production of tantalum powder by sodium reduction of TaF. The total charge passed through external circuit and average particle size (FSSS) were increased with increasing reduction temperature. The proportion of fine particle (-325 mesh) was decreased with increasing reduction temperature. The yield was improved from 65% to 74% with increasing reduction temperature. Considering the charge, impurities, morphology, particle size and yield, an reduction temperature of 1,123 K was found to be optimum temperature for MR-EMR combination process.s.
        4,200원
        2894.
        2003.11 구독 인증기관 무료, 개인회원 유료
        The articles of food is very important things to human. Since PL Law came into effect in July of the last year(2002) in Korea, many domestic firms have taken great interests in PL. And the purpose of PL Law is to provide a means for those injured by defective products to receive redress. Additionally, enterprises get to place more importance on the safety of the products, which led to improvement in competitiveness and enhancement in quality. Consequently customers can get better products. So, it aims not only to compensate the injured by defective products but also to act an incentive to maker/supliers of food to make their products more safe. Therefore, this study was aiming to analyze the expected risks to articles of food after the enforcement of PL Law, and to establish a defending plan.an.
        4,200원
        2898.
        2003.10 구독 인증기관 무료, 개인회원 유료
        Data mining technique is the exploration and analysis, by automatic or semiautomatic means, of large quantities of data in order to discover meaningful patterns and rules. This paper uses a data mining technique for the prediction of defect types in manufacturing process. The purpose of this paper is to model the recognition of defect type patterns and prediction of each defect type before it occurs in manufacturing process. The proposed model consists of data handling, defect type analysis, and defect type prediction stages. The performance measurement shows that it is higher in prediction accuracy than logistic regression model.
        4,000원
        2900.
        2003.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study examined the correlation of various operational factors including reaction temperature and the quantity of reductant and diluent with the characteristics of powder using TaF as feed materials, Na as a reductant and KCl/KF as a diluent. Also to control the particle size and shape, external supply system developed, it can provide a feed material and a reductant at a fixed quantity and evaluated the characteristics of tantalum powder. When the external supply system was applied instead of the batch type process that charges feed material, reductant and diluent at the same time, it was possible to induce regular reduction reaction between feed material and reductant, which increased the recovery rate and reduced the mixture of impurities. In particular, the application of the external supply system enabled the control of reaction temperature and reaction speed according to the feeding rate of feed material during reduced reaction, and resultantly it enabled the manufacturing of granular-shaped powder with a regular granularity of 2∼3 and purity of 99.5%.%.
        3,000원