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        검색결과 1,828

        862.
        2006.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to investigate the antioxidative effect and quality characteristics of cookies made with Sea tangle powder(STP). The cookies were at 30℃ for 45 days. The 3% STP had higher pH value compared to the other groups and control. As more STP was added, the L-value and b-value decreased, and the a-value increased for the color values. The results of sensory evaluation and acceptance test showed that the cookies with 3% STP was significantly more preferable in overall acceptability than the others. The acid value, peroxide value, and thiobarbituric acid value were lower in cookies with 3% and 6% STP than in those cookies made 9% STP and the control cookies.
        4,000원
        863.
        2006.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Electronic packaging involves interconnecting, powering, protecting, and cooling of semiconductor circuits fur the use in a variety of microelectronic applications. For microelectronic circuits, the main type of failure is thermal fatigue, owing to the different thermal expansion coefficients of semiconductor chips and packaging materials. Therefore, the search for matched coefficients of thermal expansion (CTE) of packaging materials in combination with a high thermal conductivity is the main task for developments of heat sink materials electronics, and good mechanical properties are also required. The aim of this work is to develop copper matrix composites reinforced with carbon nanofibers. The advantages of carbon nanofibers, especially the good thermal conductivity, are utlized to obtain a composite material having a thermal conductivity higher than 400 W/mK. The main challenge is to obtain a homogeneous dispersion of carbon nanofibers in copper. In this paper, a technology for obtaining a homogeneous mixture of copper and nanofibers will be presented and the microstructure and properties of consolidated samples will be discussed. In order to improve the bonding strength between copper and nanofibers, different alloying elements were added. The microstructure and the properties will be presented and the influence of interface modification will be discussed.
        4,000원
        864.
        2006.09 구독 인증기관·개인회원 무료
        The present investigation has attemped to optimize hydrogen reduction process for the mass production of Fe-8wt%Ni nanoalloy powder from ball milled powder. In-situ hygrometry study was performed to monitor the reduction behavior in real time through measurement of water vapor outflowing rate. It was found that the reduction process can be optimized by taking into account the apparent influence of water vapor trap in the reactor on reduction kinetics which strongly depends on gas flow rate, reactor volume and reduction.
        867.
        2006.09 구독 인증기관·개인회원 무료
        In the present work, the influence of the ball-milling time, milling atmosphere and weight ratio of ball to powder on characteristics of was studied. Results show that, the grain sizes of the and CuO in the ball-milled powder mixture were significantly decreased with increasing the milling time. Those of each oxide ball-milled in Argon and Hexane atmosphere for 30 and 20 hour were about 98 and 84 nm, respectively. After milling of 20 hour in Hexane as PCA, the powder had a homogeneously mixed structure and the average size of powders was determined to about 230nm.
        868.
        2006.09 구독 인증기관·개인회원 무료
        Both plastic and elastic properties change dramatically from the beginning to the end of the compaction phase. Previous investigations have shown that powder transfer and high powder flow during initial compaction at low density affects the strength of the final component significantly. Investigated here are shear failure and elastic shear modulus in the low density range for hard metal powder and for pre-alloyed water atomized iron powder. Direct shear test equipment for sand and clay has been modified to measure the shearing properties of powder for an axial loading between 1 kPa and 500 kPa.
        870.
        2006.09 구독 인증기관·개인회원 무료
        The vacuum infiltration method is one of the composite producing methods. There are several parameters in composite production by vacuum infiltration. One of them is particle size of reinforcement in particulate reinforced composites. In this study, MgO powder and Al were used as reinforcement and matrix respectively. MgO powders with different size and amount to give same height were filled in quartz tubes and liquid metal was vacuum infiltrated into the MgO powder under same vacuum condition and for same time. Infiltration height was measured and microstructure and fracture behavior of composite were investigated. It has been found that infiltration height and fracture strength were increased with particulate reinforcement sizes. It has also been determined that molten metal temperature facilitates infiltration.
        871.
        2006.09 구독 인증기관·개인회원 무료
        Mg-Zn-RE alloys had a novel lond period stacking ordered (LPO) structure. Their rapidly solidified powder metallurgy (RS P/M) alloys exhibited a combination of high strength and god ductility (tensile yield strength above 550 MPa and elongation above 5%). The LPO Mg-Zn-RE RS P/M alloys had high elevated temperature strength (tensile yield strength above 380 MPa at 473 K) and exhibited a high-strain-rate superplasticity at higher temperatures. In Japan, a national project for developing high strength LPO Mg-Zn-RE RS P/M alloys has started at 2003 for 5 years, which is founded by the Ministry of Economy, Trade and Industry (METI) of Japan. In the national project, project targets in materials performances have been achieved. The developed LPO Mg-Zn-RE RS P/M alloys exhibited higher tensile yield strength, fatigue strength and corrosion resistance than high strength aluminum alloys of extra-super-duralumin (7075-T6).
        872.
        2006.09 구독 인증기관·개인회원 무료
        alloy powders were prepared using an industrial scale gas atomizer, followed by warm extrusion. The powders were almost spherical in shape. The microstructure of powders as atomized and bars as extruded was examined as a function of initial powder size distribution using Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscope (EDS) and X-ray Diffractometer (XRD). The grain sizes were decreased with extruding as well as decreasing the initial powder sizes. Both the ultimate strength and elongation were enhanced as the initial powder sizes were decreased.
        875.
        2006.09 구독 인증기관·개인회원 무료
        For precise property control of sintered products, it is important to understand accurately the packing density of the powder. We developed a packing simulation program that could make a packed bed of spherical particles having particle size distribution. In addition, the influence of the particle shape of the actual powder on the packing density was quantitatively analyzed. The predicted packing densities corresponded well to the actual data.
        877.
        2006.09 구독 인증기관·개인회원 무료
        Cube textured Ni substrate were fabricated for YBCO coated conductors from the initial specimens prepared by powder metallurgy (P/M) and casting and the effects of annealing temperature and reduction ratio on texture formation and microstructural evolution were evaluated. The initial specimens were rolled and then annealed in the temperature at . A strong cube texture formed for P/M substrate, and the degree of texture did not significantly vary with annealing temperature of . On the other hand, the texture of casting substrate was more dependent on the annealing temperature and twin texture and several minor texture components started to form at .
        878.
        2006.09 구독 인증기관·개인회원 무료
        We fabricated Bi-2212/ composite superconductors and evaluated the effects of the powder mixing method and melting temperature on their microstructure and superconducting properties. The Bi-2212 powders were mixed with by hand-mixing (HM) and planetary ball milling (PBM) and then the powder mixtures were melted at , solidified, and annealed. We found that the powder mixture prepared by PBM was finer and more homogeneously mixed than that prepared by HM, resulting in more homogeneous microstructure and smaller and second phases after annealing.
        880.
        2006.09 구독 인증기관·개인회원 무료
        The electrochemical properties of novel metal powders were investigated for the electrode materias of polymer electrolyte memebrane electrolysis. Two types of Pt black and powder electrodes were hot-pressed on the polymer electrolyte membrane to form membrane electrode assembly. The galvanodynamic polarization methode was used to characterize the electrochemical properties of both electrodes. From the experimental results, we concluded that the powder electrode exhibits better electrochemical performance than Pt black as cathode material for the electrolysis.