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        검색결과 4,666

        2661.
        2005.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to prevent the oxide formation on the surface of nano-size iron particles and thereby to improve the oxidation resistance, iron nanoparticles synthesized by a chemical vapor condensation method were directly soaked in hexadecanethiol solution to coat them with a polymer layer. Oxygen content in the polymer-coated iron nanoparticles was significantly lower than that in air-passivated particles possessing iron-core/oxide-shell structure. Accordingly, oxidation resistance of the polymer-coated particles at an elevated temperature below in air was times higher than that of the air- passivated particles.
        4,000원
        2662.
        2005.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Aluminum matrix composites strengthened by the quasi-crystalline (QC) phase were developed in the present study. The icosahedral phase was produced by gravity casting and subsequent heat treatment. The mechanical milling process was utilized in order to produce the Al/QC composite powders. The microstructures of the composite powders were examined by optical microscopy (OM) and scanning electron microscopy (SEM). The composite powders were subsequently canned, degassed and extruded in order to produce the bulk composite extrusions with various volume fractions of QC. The microstructure and mechanical properties of the extrusions were examined by OM, SEM, Vickers hardness tests and compression tests. It was found that the microstructures of the Al/QC composites were uniform and the mechanical properties could be significantly improved by the addition of the QC phase.
        4,000원
        2663.
        2005.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Ultrafine copper powder was prepared from slurry with hydrazine, a reductant, under . The influence of various reaction parameters such as temperature, reaction time, molar ratio of , PvP and NaOH to Cu in aqueous solution had been studied on the morphology and powder phase of Cu powders obtained. The production ratio of Cu from CuO was increased with the ratio of and the temperature. When the ratio of was higher than 2.5 and the temperature was higher than , CuO was completely reduced into Cu within 40 min. The crystalline size of Cu obtained became fine as the temperature increase, whereas the aggregation degree of particles was increased with the reaction time. The morphology of Cu powder depended on that of the precursor of CuO and processing conditions. The average particle size was about
        4,000원
        2664.
        2005.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper deals with the fabrication of titanium carbide using fine titanium hydride. The ratio of and C (Activated carbon) was 1:1 (mol) and milled in a planetary ball mill at a ball-to-powder weight ratio of 20:1. Thereafter, TGA was performed at to observe change of weight with milling time. Titanium carbide was obtained by using tempering the milled powders at . The microstructures of titanium carbide as well as the change of the lattice parameters and particle size have been studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM).
        4,000원
        2676.
        2005.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Methionine과 xylose를 이용한 Maillard 반응생성물을 첨가하고 autoclaving mothod로 중화요리용 향미유를 제조하였다. 이 향미유와 서울 시내 중국 음식점에서 자장면용 양념자장 3종을 구하여 이들의 휘발성 물질을 GC, GC-MSD로 측정하였다. 향미유에서는 61종, 404.92ppm의 휘발성 물질이 분리 정량 되었고, 양념자장 3종에서는 각각 39종, 42종, 42종이 확인 되었으며, 그 양은 각각 333.52ppm, 330.01ppm, 393.18ppm이었다. 중화요리용 향미유의 주요 휘발성 성분은 diallyl disulfde, pentane, diallyl trisulfide, t, t-2, 4-decadienal 및 zinngiberene이었으며, 이들의 함량은 각각 40.15ppm, 32.32ppm, 19.57ppm, 15.06ppm 및 13.23ppm이었다. 시중 자장시중 3종에서는 pentane, propenal, hexanal, t-2-heptanal, 2, 4-heptadienal, t, t-2, 4-decadienal 및 미확인 물질이었다. 본 실험에서 제조한 향미유는 3종류의 sample과 유사한 향미 물질을 포함하고 있었으며 aldehyde, ethane, alcohol 등의 함량은 낮은 편이었다.
        4,000원