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Volume 55 , Issue 3
Showing 1-7 articles out of 7 articles from the selected issue
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Original Papers
  • K. O. KWON, M. G. LEE, K. R. KONG, H. C. KANG
    Volume 55 (2008) Issue 3 Pages 115-119
    Released: September 12, 2008
    JOURNALS FREE ACCESS
    The study measures the effect of domestic kaolin on the compressive strength of cement mortar and lightweight porous concrete. The kaolin was thermally treated in an electric furnace at T = 800°C for a pozzolan reaction. Cement mortar and lightweight porous concrete were used to compare the effect of adding meta-kaolin (0%~30%). As a result, mixture with 10%~15% meta-kaolin obtained the highest compressive strength. The tests were also applied to investigate the effect of a meta-kaolin particle size in lightweight porous concrete. The mixtures were made by replacing cement with 15% meta-kaolin while varying the particle size of meta-kaolin. The lightweight porous concrete with 38~48 μm meta-kaolin in 15% replacement develops 100% higher compressive strength than no addition of meta-kaolin.
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  • K. S. BARTWAL, Hojin RYU
    Volume 55 (2008) Issue 3 Pages 120-123
    Released: September 12, 2008
    JOURNALS FREE ACCESS
    Solid solution of barium strontium aluminate, Sr/BaAl2O4: Eu2+ co-doped with Dy3+ was prepared by solid state reaction method. The prepared phosphor compositions with varying Dy3+ compositions were investigated by powder X-ray diffractometer (XRD), SEM, TEM and photoluminescence (PL) excitation and emission spectra. Long persistent luminescence was observed in these phosphor materials. The broad band UV excited luminescence of the Sr/BaAl2O4:Eu2+:Dy3+ was observed in the green region (λmax = 500 nm) due to transitions from the 4f65d1 to 4f7 configuration of the Eu2+ ion. Effects of co-doping of Dy3+ on the photoluminescence properties of these compositions were investigated.
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  • Uong CHON, Ki Young KIM, Cheol Gyu LEE
    Volume 55 (2008) Issue 3 Pages 124-131
    Released: September 12, 2008
    JOURNALS FREE ACCESS
    Fatigue-free and highly c-axis oriented Bi4-xSmxTi3O12 (BSmT; x = 0.85) thin films were grown on Pt/TiO2/SiO2/Si(100) substrates using the method of metal-organic sol decomposition. The BSmT film capacitor with a top Pt electrode showed significantly improved values of the remanent polarization (Pr) and the nonvolatile charge as compared to those of the Bi4-xLaxTi3O12 (BLT; x = 0.75) film capacitor, recently known as a promising candidate for nonvolatile memories. The 2Pr value of the BSmT capacitor was 49 μC/cm2 at an applied voltage of 10 V while the net nonvolatile charge was as high as 20 μC/cm2 and remained essentially constant up to 4.5 × 1010 read/write switching cycles at a frequency of 1 MHz. In addition to these, the capacitor showed excellent charge-retention characteristics with its sensing margin of 17 μC/cm2 and a strong resistance against the imprinting failure.
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  • J. E. GEBHARDT, M. CROSS, T. N. CROFT, L. MARKS
    Volume 55 (2008) Issue 3 Pages 132-138
    Released: September 12, 2008
    JOURNALS FREE ACCESS
    Multi-physics modeling tools offer engineers a way to effectively and economically evaluate design options and optimize operating strategies for a variety of metallurgical and manufacturing processes. Many of these processes involve complex physical and chemical phenomena that are coupled and inter-related within the multi-physical domain. Two applications of multi-physics modeling are described: heap leach model (reactive dissolution and flow through a static porous bed) and effects of bubbles, droplets, and particles in metals reduction and refining.
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  • Toru OISHI, Takashi FURUYAMA, Eiji SAKAMOTO, Yuji TACHIZUKA
    Volume 55 (2008) Issue 3 Pages 139-143
    Released: September 12, 2008
    JOURNALS FREE ACCESS
    The removal of ferric ions from acid mine water was investigated with the neutralizer of recycled rock wool (RRW) in this study. The performance on the removal of ferric ions by the neutralizer of RRW was also compared with that in the neutralizer of virgin rock wool (VRW). Some wastes like the materials from rock wool fire-resistant cover of steel-frame buildings, rock wool insulator wastes of thermal power plants and so on were collected in order to make RRW. In the intermediate process, the objectives were separated and other matters were removed. Sample particles were made after adding blast furnace cement and water as a binder to the objectives and mixing together. When the cumulative volume of passing water increased at the average rate of passing water from 3.85 to 3.89 L/day, the removal performance of ferric ions on RRW was inferior to that on VRW. It is considered that since RRW has larger bulk density, that is, smaller specific surface area, the chemical reactivity of RRW is inferior to that of VRW. When the average rate of passing water was changed from 1.81 to 1.91 L/day, the removal performance of ferric ions on RRW was almost equal to that on VRW.
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  • T. NAKAMURA, E. SHIBATA, T. TAKASU, H. ITOU
    Volume 55 (2008) Issue 3 Pages 144-148
    Released: September 12, 2008
    JOURNALS FREE ACCESS
    Electric Arc Furnace (EAF) dust, defined as special industrial waste in Japan, is treated through pyrometallurgical processes in which crude ZnO powder is recovered. An on-site type process, however, is desired to reduce treatment cost and cost of transportation of the dust. A hydrometallurgical process is considered to be suitable for such an on-site treatment. Although many EAF dust treatment processes by hydrometallurgical method have been proposed, most of them have not been commercialized in Japan. A short review of hydrometallurgical processes for EAF dust was done and a new hydrometallurgical process for EAF dust was proposed in this study. Nitric acid solution is used for the extraction of ZnO from the dust. Some characteristics of the process are as follows:
    (1) Recovery of Zn from zinc ferrite in EAF dust is the target, while the dissolution of Fe is limited by controlling the pH of the solution.
    (2) Zn is recovered as metallic Zn by electrowinning from the solution and nitric acid is regenerated in the anode.
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  • Eishi KUSAKA, Atsushi YOKOI
    Volume 55 (2008) Issue 3 Pages 149-155
    Released: September 12, 2008
    JOURNALS FREE ACCESS
    The effects of hydrolysable metal salts on the flotation of potato starch with anionic surfactant, sodium dodecylsulfate, were investigated. It was presented that negatively charged starch surface was activated by the hydrolysable metal salts of Al(III), Fe(III), Cu(II) and Ni(II). The pH range in which the activation was observed ranged from the precipitation pH of each metal hydroxide to the isoelectric point, IEP, of each hydroxide precipitate. SEM images indicated that starch particles were covered with hydroxide precipitate above the precipitation pH. The results of adsorption test and micro electrophoresis indicated that the effect of adsorbed hydroxy complex was not sufficient to reverse the negative charge of starch surface. These results suggested that in the anionic flotation of starch it was not hydroxy complexes but hydroxide precipitates that acted as an activating species which modified the starch particle surface.
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