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        검색결과 1,429

        101.
        2022.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 실험에서는 α-Al2O3 세라믹 중공사를 지지체로 사용하였고, 무전해 도금을 통해 Pd 및 Pd-Ag가 도금된 수소 분리막을 제조하였다. Pd-Ag 분리막은 Pd와 Ag 합금 형태로 만들기 위하여 500°C, 10 h 동안의 annealing 과정을 거쳤으며, EDS (Energy Dispersive X-ray Spectroscopy) 분석을 통해 Pd-Ag 합금이 되었다는 것을 확인하였다. 또한, SEM (Scanning Electron Microscope) 분석을 통해 제조된 Pd 및 Pd-Ag 도금층의 두께는 약 8.98, 9.29 μm으로 측정되었다. 제조된 수소 분 리막은 350~450°C, 1-4 bar의 범위에서 수소 단일 가스, 혼합가스(H2, N2)를 이용하여 수소 투과 실험을 진행하였다. 수소 단 일 가스에서 Pd와 Pd-Ag 분리막은 최대 각각 21.85, 13.76 mL/cm2⋅min의 flux를 가지며, 혼합가스에서는 450°C, 4 bar의 조건일 때, 1216, 361의 separation factor가 각각 나오는 것을 확인하였다.
        4,000원
        117.
        2022.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Herein, a facile bottom–up approach for producing nitrogen-doped carbon quantum dots (N-CQDs) was carried out by the hydrothermal treatment of microcrystalline cellulose, in the presence of different nitrogen sources (blank/urea/ammonia water/ethanediamine(EDA)/Hexamethylenetetramine). The result showed that the fluorescence intensity and quantum yields (QYs) of N-CQDs with different nitrogen sources are all higher than that without nitrogen source. Compared with the other three nitrogen sources, N-CQDs prepared by EDA not only have the highest fluorescence intensity but also the largest QYs of 51.39%. Therefore, EDA was chosen as the nitrogen source to prepare N-CQDs. The obtained N-CQDs are uniform spherical particles with a diameter of 2.76 nm. The N-CQDs also exhibit excitation-dependent and long-wave emission properties. The emission range of N-CQDs is 470–540 nm. Moreover, N-CQDs as fluorescent agents successfully acted on purple LEDs (λem = 365 nm) to achieve white LEDs light emission. At the same time, a fluorescent thin layer chromatography plate was successfully prepared using N-CQDs, silica gel G and Sodium carboxymethylcellulose as raw materials. The separation trajectory of mixed sample of Sudan red III and kerosene on the fluorescent TLC plate is obviously clearer than that of the TLC plate.
        4,000원
        118.
        2022.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Abstract Recently, the circular economy aiming at elimination of waste and the continual use of resources has attracted a lot of attentions. In the circular system, the resource recovery uses the recycled wastes as the raw material to manufacture new valuable products. This work focuses on a low-cost process, in which an activated carbon (AC) adsorbent was prepared from waste cation exchange resin by calcination and HNO3 activation hydrothermal method. Surface structure and chemistry of AC were characterized by SEM, XRD, FTIR and Boehm titration. It was found that the acid treatment could increase the number of pores and the content of oxygen-containing functional groups on AC surface. In the adsorption experiment, Methylene blue (MB) was used to assess the adsorption capacity of AC. Experimental results showed that the highest efficiency of MB removal was achieved by AC with modification of 4M HNO3, showing the acidification effect on the adsorption capacity of AC. Adsorption isotherms of Langmuir and Freundlich were employed to fit the experimental data. It was shown that MB adsorption on AC is more consistent with Langmuir model that assumes a homogeneous adsorption. In the adsorption kinetic analysis, the adsorption was found to follow the pseudo-second-order model, indicating that adsorption of MB on acidified AC is dominated by chemical adsorption. The study revealed that the waste ion-exchange resin is a proper precursor of carbon adsorbent for MB dye. This low-cost method would specifically reduce the environmental cost of waste disposal.
        4,600원
        119.
        2022.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        목적 : 본 연구는 Polydimethylsiloxane(PDMS)를 기반으로 다양한 첨가제를 사용하여 고 기능성 안 의료용 고분자를 제조한 후, 제조된 렌즈 표면에 생체적합성 및 습윤성이 우수한 collagen을 코팅하여 물성을 비교 분석 하였다. 방법 : 렌즈 제조를 위해 PDMS와 친수성 모노머인 N,N-dimethylacrylamide(DMA), 2-Hydroxyethyl methacrylate(HEMA)를 주재료로 사용하였으며, 교차결합제인 Ethylene glycol dimethacrylate(EGDMA)와 열 개시제인 Azobisisobutyronitrile(AIBN)을 사용하였다. 또한 기능성 첨가제로는 1,3-Bis(3-aminopropyl) tetramethyldisiloxane(TMDS), Polyvinylpyrrolidone(PVP), 2-(Trifluoromethyl)styrene 및 collagen을 사 용하였다. 제조된 렌즈의 물성 평가를 위해 광투과율, 굴절률, 함수율, 산소투과율 그리고 인장강도를 각각 측정하였으 며, 접촉각 측정을 통해 습윤성을 평가하였다. 결과 : TMDS의 첨가비율에 따라 렌즈의 산소투과율은 약 28~45 ×10⁻¹¹(cm²/sec)(mlO²/ml×mmHg)으로 나타내었으며, PVP 및 2-(Trifluoromethyl)styrene가 첨가된 렌즈의 습윤성 및 인장강도는 56~46° 그리고 0.11~0.17 kgf/mm² 의 범위로 각각 나타났다. 다양한 첨가제를 사용함으로써 제조된 렌즈의 기능성이 향상되었 으며, 특히 콜라겐 첨가제의 사용은 하이드로겔 표면의 접촉각을 매우 감소시켜 우수한 습윤성을 가지는 것으로 나타났다. 결론 : TMDS, PVP 그리고 2-(Trifluoromethyl)styrene은 실리콘 하이드로겔 렌즈의 기능성 향상에 효과적 이며, 첨가제로서의 collagen 사용은 렌즈의 습윤성을 향상시키는 것으로 나타나 본 연구에서 사용된 재료는 안의 료용으로 다양하게 활용될 수 있을 것으로 판단된다.
        4,000원
        120.
        2022.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We have prepared MIL-101/graphene oxide (GO) composites with various mixing molar ratio of Fe-containing metal– organic frameworks (MOFs) against GO. When synthesizing MOFs, it was possible to synthesize uniform crystal powders using hydrothermal method. MIL-101 consists of a terephthalic acid (TPA) ligand, with the central metal composed of Fe, which was the working electrode material for supercapacitors. Field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy analysis had been done to ascertain microstructures and morphologies of the composites. Cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge–discharge measurements were performed to analyze the electrochemical properties of the composite electrodes in 6 M KOH electrolyte. By controlling the metal ligand mole ratio against GO, we prepared a changed MOF structure and a different composite morphology, which could be studied as one of the promising optimized electrode materials for supercapacitors.
        4,200원