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        검색결과 5

        1.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Carbon dots (CDs) were synthesized from phloroglucinol (PG) by simple heat treatment at 220–230 °C in the atmosphere without catalysts and solvents. PG-CDs heated at 220–230 °C could be completely dissolved in environmentally friendly water and exhibited a photoluminescence (PL) peak at 485 nm with 85 nm of the full width at half maximum (FWHM). The water-soluble polymer-dot-like PG-CDs were estimated to be 1.6–3.2 nm in size, and exhibited a wide range of PL wavelength at 370–630 nm. Since the PG-CDs are water-soluble materials, PG-CDs could be homogeneously mixed with a polymer such as polyvinylpyrrolidone (PVP) in water as a solvent, and PG-CDs/PVP films were prepared. The films exhibited PL characteristics that convert ultraviolet light at 350 nm to visible light above 400 nm. Thus, using PG as the raw material which has widely been produced industrially, the water-soluble fluorescent PG-CDs/PVP films could be prepared at a low cost by environmentally friendly methods.
        4,000원
        2.
        2023.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This work describes the synthesis and characterization of a heterogeneous catalyst consisting of piperazine-functionalized reduced graphene oxide decorated with Fe3O4 nanoparticles ( Fe3O4@rGO-NH), and the study of its catalytic activity as a magnetic heterogeneous catalyst for the Pechmann synthesis of coumarins. Catalyst Fe3O4@ rGO-NH was fully characterized by various techniques, including IR, XRD, TEM, VSM, TGA, and elemental analysis. Then, the catalyst was used as an efficient and easy-separable heterogeneous catalyst for the solvent-free synthesis of some coumarins by Pechmann reaction. The reaction was optimized in terms of reaction time and temperature, catalyst dosage, and the presence/absence of the solvent. Finally, the reusability of the catalyst was studied.
        4,000원
        3.
        2011.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigated the effect of solvent on the fabrication of Ni-free Fe-based alloy nano powders by employing the PWE (pulsed wire evaporation) in liquid and compared the alloy particles fabricated by three different methods (PWE in liquid, PWE in Ar, plasma arc discharge), for high temperature oxidation-resistant metallic porous body for high temperature soot filter system. Three different solvents (ethanol, acetone, distilled water) of liquid were adapted in PWE in liquid process, while X-ray diffraction (XRD), field emission scanning microscope (FE-SEM), and transmission electron microscope (TEM) were used to investigate the characteristics of the Fe-Cr-Al nano powders. The alloy powder synthesized by PWE in ethanol has good particle size and no surface oxidation compared to that of distilled water. Since the Fe-based alloy powders, which were fabricated by PWE in Ar and PAD process, showed surface oxidation by TEM analysis, the PWE in ethanol is the best way to fabricate Fe-based alloy nano powder.
        4,000원
        4.
        2006.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Solvent-free low foaming scouring agents (LFSC) were prepared by blending of 2-ethylhexylaminoethyl sulfate (2-EHAS), POE(10) octadecylbenzyl- ammonium chloride (POBAC) and Sedlan FF-200 (FF-200). As the results of several tests, 2-EHAS/POBAC/FF-200/water (8g/12g/20g/60g) mixture (LFSC-5) showed good cleaning power, penetrating ability and stability to alkali, and gave less problem in water pollution. The foaming power of LFSC-5 measured by Ross and Miles method was 8mm foam height immediately after foaming, and that measured by Ross and Clark method was less than 300mm foam height at 30℃, and 18mm at 80℃. As a result, LFSC-5 proved a good low foaming scouring agent for fiber.
        4,000원
        5.
        1998.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Methyl fructoside oleic acid polyester(MFPE), fructose-based sugar polyester, was synthesized by solvent-free, soap-free transesterification of methyl oleate with methyl fructoside(MF) as a sugar starting material in the presence of conventional potassium carbonate basic catalyst. Methyl fructoside was found to be an effective sugar starting material, because of its low softning point, high heat stability, high miscibility, and high reactivity than other sugars. Yield 98% of purified MFPE based on initial weight of MF was obtained at 1:5 of the molar ratio of methyl fructoside to methyl oleate, 2%(w/w) of potassium carbonate catalyst content, 20~200mmHg of reduced pressure and 180℃ of reaction temperature. MFPE structure was confirmed by infrared and proton nuclear magnetic resonance spectroscopy. Physical properties of methyl of fructoside oleic acid polyester such as viscosity, HLB, solubility, color, refractive index, specific gravity, and density were similar to physical properties of sucrose polyesters(SPE) and vegetable oils. Then, it was elucidated that MFPE was sufficient to replace the SPE and conventional oils.
        4,300원