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        검색결과 120

        1.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this research, in order to increase the oxidation resistance of graphite, kaolin and alumina powder with different ratios (26A-74S, 49A-51S, 72A-28S) and slurry method were used to create an aluminosilicate coating on the graphite substrate. In order to reduce the difference in the coefficients of thermal expansion of graphite with aluminosilicate coating, aluminum metaphosphate coating as an interlayer was prepared on the surface of graphite by cathodic electrochemical treatment. The isothermal oxidation test of the samples was carried out in air at a temperature of 1250 °C for 1, 3 and 5 h. The microstructure, chemical composition, and phase components of the coating were, respectively, analyzed by scanning electron microscope equipped with an energy-dispersive spectrometer and X-ray diffraction. The results indicated that, by increasing the withdrawal speed of the samples in slurry method, the amount of changes in the weight of the samples has increased and therefore had a direct effect on oxidation. In addition, it was approved that, at high-temperature oxidation, AlPO4 glass phase forms on aluminum metaphosphate interlayer which retards graphite oxidation. Along with aluminum metaphosphate, aluminosilicate coating also produces a glass phase which fills and seals the voids on the surface which prevents the oxygen to reach the surface of graphite. The created double-layer coating including an interlayer of aluminum metaphosphate + slurry coating prepared with the ratio of 26A-74S as the optimal coating in this research was able to increase the oxidation resistance of graphite by 73% at a temperature of 1250 °C.
        4,600원
        2.
        2022.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The carbon-based nanostructures are in limelight due to their widespread applications in nano-to-micro-scale technologies. The carbon dots are known for their unique physical, electrical, optical, chemical and biological properties. The carbon dots (CDs) are being produced through several well-developed synthesis methods, one of which is the green sonochemical. This method is preferred over others because it is a green source of energy, facile, fast, low-temperature process, non-toxic and less expensive. Despite the fact of using 90% less energy than other methods, this method has been overlooked in the published literature. It is possible to prepare pure and doped CDs of low toxicity and controlled physicochemical properties through sonochemical method. In recent years, sonochemically produced CDs have been tuned and characterized for a variety of applications. This review has explored the merits and demerits of sonochemical method in comparison to the other methods for the synthesis of pure CDs and their nanocomposites. The role of multiple factors in tailoring the specific parameters of CDs for their application in antibacterial, polymerization, tissue engineering, catalysis, bio-imagining, supercapacitors, drug delivery and electric devices is also elaborated in this review. This review also concludes on future directions in the applications of sonochemically produced CDs.
        5,100원
        3.
        2021.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Most recently, graphene-related composite-modified electrode surfaces are been widely employed to improve surface interactions and electron transfer kinetics. Hydrothermally prepared strontium pyro niobate (SPN) and reduced graphene oxide/ strontium pyro niobate (RGOSPN) nanostructures reveal excellent morphology. X-ray diffraction analysis of SPN and RGOSPN agree with standard data. Thermogravimetry–differential scanning calorimetry analyses show that RGOSPN has higher thermal stability than SPN. In addition, from the polarization–electric field (P–E) loop measurements, the estimated value of remnant polarization (Pr) and coercive electric field (Ec) of SPN are 0.039 μC cm−2 and − 2.90 kV cm−1 and that of RGOSPN nanocomposite are 0.0139 μC cm−2 and − 2.04 kV cm−1. Cyclic voltammetry measurements show that RGOSPN nanocomposite manifests the possibility of electrochemical reversibility beyond long cycles without change in performance. The redox cycle reveal that RGOSPN can be used as part of a composite electrode for hybrid capacitors dynamic conditions. Moreover, the specific capacitance of SPN and RGOSPN was calculated using galvanostatic charge–discharge (GCD) technique. The observed energy density of 9.1 W h kg−1 in RGOSPN is higher when compared with previous reported values.
        4,800원
        5.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Carbon short fibers/copper composites with different carbon short fiber contents up to 15 wt.% as reinforcements are prepared to investigate the influence of the carbon short fiber surface coating on the microstructure, density, and electrical properties of the carbon short fibers/copper composites. The carbon short fibers were surface treated by acid functionalization followed by alkaline treatment before the coating process. It was observed from the results that coated type copper nanoparticles were deposited on the surface of the carbon short fibers. The surface treated carbon short fibers were coated by copper using the electroless deposition technique in the alkaline tartrate bath by using formaldehyde as a reducing agent of the copper sulfate. The produced coated carbon short fibers/copper composite powders were cold compacted at 600 MPa, and then sintered at 875 °C for 2 h under (hydrogen/nitrogen 1:3) atmosphere. A reference copper sample was also prepared by the same method to compare between the properties of pure copper and the carbon short fibers/copper composites. The phase composition, morphology, and microstructure of the prepared carbon short fibers/copper composite powders as well as the corresponding carbon short fibers/copper composites were investigated using X-ray diffraction analysis (XRD) and scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer (EDS), respectively. The density and the electrical resistivity of the sintered composites were measured. It was observed from the results that the density was decreased; however, the electrical resistivity was increased by increasing the carbon short fibers wt.%.
        4,300원
        10.
        2018.07 구독 인증기관·개인회원 무료
        With the introduction of virtual reality (VR) devices for private consumers in 2013, the industry experience great attention and notable progresses have been made in relation to hardware components (Papagiannidis et al. 2013). This enables better experiences of virtual environments and reduces the awareness of the consumer to be exposed to virtual stimuli, so that the virtual environment is perceived as (almost) real – the so-called immersion effect (Grau 2003). Even though VR is already in place, little research in service marketing literature exists about it (Bigné, Llinares, and Torrecilla 2016), so that this technique represents one of the most important topics to investigate from service perspective (Kannan and Li 2017). We assume that the immersion-effect might influence the perception of the service encounter and thus influence consumer evaluation in a new way. Thereby, we contribute to service marketing literature by exploring the value and barriers for VR usage in so-called virtually-extended service encounters from a customer perspective. Thereby, we further examine for which kind of services VR is useful, how consumer perceive VR technology in service environments and how the extension of the traditional service encounter by VR technology influences consumers’ service quality evaluations. VR represents a promising technology to promote high-involvement products or services like travel, furniture, or cars. Companies offering these kind of products and services can provide simple devices to customers, who can experience the product in a realistic setting upfront their purchase decisions. Especially novelty and innovation characteristics of VR-technology may have positive spillover effects on company brand, the product as well as the final purchase decision. To proceed with this research, we plan lab experiments with well-developed VR-devices.
        11.
        2018.07 구독 인증기관·개인회원 무료
        Researchers have yet to investigate whether it is beneficial for exporters to engage in greater levels of product adaptation in their export operations, or whether there is some limit to the amount of adaptation exporters should engage in. We posit that customer value creation, a central marketing concept and a mechanism to achieving market and financial goals in business to business markets, is a core outcome of export product adaptation activities. In order to explore the routes by which adaptation may shape export customer value creation, we adopt a multi-faceted conceptualization of firm-level product adaptation, comprising export product adaptation (i) quantity, (ii) intensity and (iii) novelty. Drawing on survey data from 249 Finnish exporters involved in business-to-business activities, we find evidence to support the claim that the impact of export product adaptation on export customer value creation is contingent on various factors, and we identify instances where greater adaptation is beneficial for export customer value creation, and instances where greater export product adaptation is potentially harmful for export customer value creation.
        12.
        2018.07 구독 인증기관·개인회원 무료
        Despite growing research interest in consumer health, well-being and beauty, little is known about factors influencing consumer purchase decisions for female fitness devices. This study focuses on Kegel exercises – exercise routines developed by Dr. Kegel to strengthen pelvic floor muscles – that are recommended by health professionals for patients experiencing health ailments such as urinary incontinence, sexual dysfunction, and dissatisfaction. Despite the benefits, women are not well aware of the role of pelvic floor muscles. The diffusion and acceptance of Kegel exercise and devices among women are likely determined by how comfortable women are about obtaining such benefits. For this reason, feminism should play an important role in shaping women’s desire to engage in Kegel exercises. Thus, this research investigates how feminism is related to Millennial women’s engagement with fitness products, particularly Kegel devices. Drawing on the literatures about sexuality, health, and marketing, we propose that feminism positively influences women’s health-related attitudes (i.e., attitudes towards fitness, fitness opinion leadership, attitude toward core strength, and desire to control sex life), which in turn positively impacts women’s fitness engagement. Fitness engagement, in turn, is expected to predict attitudes towards Kegel exercise and Kegel device purchase intentions. On the other hand, women’s attitudes toward core strength and desire to control sex life are proposed to have a direct, positive impact on attitude towards Kegel exercise. Analysis of PLS-SEM shows general support for the hypotheses. We discuss how interest in Kegel devices could, in turn, lead to positive effects on overall physical and psychological health and provide implications for marketing practitioners.
        13.
        2018.07 구독 인증기관 무료, 개인회원 유료
        This research was conducted with the aim to reveal the influence of online travel communities on tourism destinations choice, with the focus on the Russian tourism market. The preliminary results indicated that social media has significant influence on consumer behaviour and decision-making process of Russian travellers. Still, there is additional activity of Russian tourist market actors is needed to more fully use the opportunities of online travel communities.
        4,600원
        18.
        2017.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The Korea Astronomy and Space Science Institute plans to develop a coronagraph in collaboration with National Aeronautics and Space Administration (NASA) and to install it on the International Space Station (ISS). The coronagraph is an externally occulted one-stage coronagraph with a field of view from 3 to 15 solar radii. The observation wavelength is approximately 400~nm, where strong Fraunhofer absorption lines from the photosphere experience thermal broadening and Doppler shift through scattering by coronal electrons. Photometric filter observations around this band enable the estimation of 2D electron temperature and electron velocity distribution in the corona. Together with a high time cadence ($<$12~min) of corona images used to determine the geometric and kinematic parameters of coronal mass ejections, the coronagraph will yield the spatial distribution of electron density by measuring the polarized brightness. For the purpose of technical demonstration, we intend to observe the total solar eclipse in August 2017 with the filter system and to perform a stratospheric balloon experiment in 2019 with the engineering model of the coronagraph. The coronagraph is planned to be installed on the ISS in 2021 for addressing a number of questions (e.g., coronal heating and solar wind acceleration) that are both fundamental and practically important in the physics of the solar corona and of the heliosphere.
        4,200원
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