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        검색결과 5

        1.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        For practical applications of graphene sheets in a variety of fields, mass production of high-quality graphene sheets is necessary. Herein, we reported a cost-effective, green, and simple approach to synthesizing mass production exfoliated graphene (EG) flakes employing electrochemical exfoliation of pencil graphite in neutral aqueous electrolytes. Pencil graphite cores of different grades were applied as anode and cathode electrodes and exposed to the electrolyte solution at a different voltage. Several parameters were examined and optimized, including pencil grade (2,4,6,8 B), applied voltage (10, 15, 20, 30 V), different inorganic electrolytes ((NH4)2SO4, Na2SO4, NaNO3, NaCl, and CH3COONa), and the concentration of electrolytes. The optimal condition was chosen by considering the mass of produced graphene and the conductivity of the graphene solution. The optimal conditions were as follow: pencil grade: 6B; applied voltage: 10 V; electrolyte type: Na2SO4; electrolyte concentration: 0.1 M. Under these conditions, the production yield was > 95% within 3 h and 9 min. The EG was characterized by utilizing FT-IR, XRD, Raman spectroscopy, FE-SEM, Cyclic Voltammetry, and Electrochemical Impedance Spectroscopy (EIS). Characterization indicates that the synthesized EG had an XRD peak at 2θ = 26.6° and an ID/ IG ratio of 0.36. Furthermore, the EG showed good conductivity when tested by cyclic voltammetry and EIS whereas the R2 values were 985.8 and 76.3 Ω for bare GCE and EG/GCE, respectively. In addition, EG effectively removed cadmium (Cd(II)) with an adsorption level of 8.72 mg/g. The results from this study suggest that EG can be scaled up and commercialized in an environmentally friendly and low-cost manner, especially in low-income countries, and using it to rectify metal ions.
        4,200원
        2.
        2021.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Here, Zn ferrite is synthesized along with reduced graphene oxide (rGO) by a facile one-step hydrothermal method. The difference between the synthesized nanocomposites with those in other reported work is that the reaction conditions in this work are 160 oC for 12 h. The synthesized products are characterized by field-emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and attenuated total reflection. Further, the adsorption property of rGO–Zn ferrite (rGZF) nanocomposite is studied after confirming its successful synthesis. The adsorption capacity of rGZFs toward rhodamine B (RB) is ˃ 9.3 mg/g, whereas that of bare ZF nanoparticles is 1.8 mg/g in aqueous media. The efficiencies of rGZF and bare ZF to remove RB are 99 % and 20 %, respectively. Employing rGZF, 60 % of RB is decomposed within 5 min. The kinetic study reveals that the adsorption process of removing RB by bare Zn ferrite follows pseudo-firstorder kinetics. However, after zinc ferrite is incorporated with rGO, the kinetics changes to pseudo-second-order. Furthermore, the Langmuir isotherm is accomplished by the adsorption process employing rGZF, indicating that a monolayer adsorption process occurs. The thermodynamic parameters of the process are also calculated.
        4,000원
        3.
        2013.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Nanosphere lithography is an inexpensive, simple, high-throughput nanofabrication process. NSL can be done in different ways, such as drop coating, spin coating or by means of tilted evaporation. Nitride-based light-emitting diodes (LEDs) are applied in different places, such as liquid crystal displays and traffic signals. The characteristics of gallium nitride (GaN)-based LEDs can be enhanced by fabricating nanopatterns on the top surface of the LEDs. In this work, we created differently sized (420, 320 and 140 nm) nanopatterns on the upper surfaces of GaN-based LEDs using a modified nanosphere lithography technique. This technique is quite different from conventional NSL. The characterization of the patterned GaN-based LEDs revealed a dependence on the size of the holes in the pattern created on the LED surface. The depths of the patterns were 80 nm as confirmed by AFM. Both the photoluminescence and electroluminescence intensities of the patterned LEDs were found to increase with an increase in the size of holes in the pattern. The light output power of the 420-nm hole-patterned LED was 1.16 times higher than that of a conventional LED. Moreover, the current-voltage characteristics were improved with the fabrication of differently sized patterns over the LED surface using the proposed nanosphere lithography method.
        4,000원
        4.
        2006.04 구독 인증기관·개인회원 무료
        The process of coprecipitation of biocomposite hydroxyapatite/chitosan from aqueous solution at low temperature in alkali environnement was examined. We have shown that initially we have the formation of amorphous octocalcium phosphates and the transferring from OCP to amorphous calcium phosphate , and then from TCP to calcium-deficient hydroxyapatite and hydroxyapatite . The transformation of ACP to HAP was inhibited in the presence of chitosan. The result suggests that there is an affinity binding between ACP and chitosan and subsequently blocking the active growth site of ACP.
        5.
        2019.04 KCI 등재 서비스 종료(열람 제한)
        Purpose – This research explores the impacts of third-party logistics (3PLs) within the aircraft Maintenance, Repair and Overhaul (MRO) industry in the United Arab Emirates (UAE) to explore the role of collaborative relationships for improving outsourcing. Globalization and time based competition have changed business environments and challenged the conventional management strategies that are related to core competencies and operational models. Organizations are forced to devise innovative practices in which logistics outsourcing to 3PLs offers significant advantages. Research design, data, and methodology – This case study was conducted within a leading global aircraft MRO organization whose reach spans across Europe, the Middle East, Asia and the Americas. The methods used face to face semi-structured interviews, validated through further focus group discussions. Results – These findings highlight the effectiveness of collaborative relationships on their role to improve outsourcing and also demonstrated that MROs gain several advantages from 3PL arrangements. However, any gaps in outsourcing management elevates potential risks to organizations as well, which could result in reputational, operational and financial losses. Conclusions – Although generalizability is not possible due to the case study approach, generality suggests that in order to reduce reputational, operational and financial risks, enhanced collaboration with 3PLs is recommended to optimize outsourcing arrangements.