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        검색결과 7

        1.
        2023.05 구독 인증기관·개인회원 무료
        Aluminum’s exceptional properties, such as its high strength-to-weight ratio, excellent thermal conductivity, corrosion resistance, and low neutron absorption cross-section, make it an ideal material for diverse nuclear industry applications, including aluminum plating for the building envelope of nuclear power plants. However, plating aluminum presents challenges due to its high reactivity with oxygen and moisture, thus, complicating the process in the absence of controlled environments. Plating under an inert atmosphere is often used as an alternative. However, maintaining an inert atmosphere can be expensive and presents an economic challenge. To address these challenges, an innovative approach is introduced by using deep eutectic solvents (DES) as a substitute for traditional aqueous electrolytes due to the high solubility of metal salts, and wide electrochemical window. In addition, DESs offer the benefits of low toxicity, low flammability, and environmentally friendly, which makes DESs candidates for industrial-scale applications. In this study, we employed an AlCl3-Urea DES as the electrolyte and investigated its potential for producing aluminum coatings on copper substrates under controlled conditions, for example, current density, deposition duration, and temperature. A decane protective layer, non-polar molecular, has been used to shield the AlCl3-Urea electrolyte from the air during the electrodeposition process. The electrodeposition was successful after being left in the air for two weeks. This study presents a promising and innovative approach to optimizing aluminum electrodeposition using deep eutectic solvents, with potential applications in various areas of the nuclear industry, including fuel cladding, waste encapsulation, and radiation shielding.
        2.
        2022.05 구독 인증기관·개인회원 무료
        Decontamination of spent nuclear fuel from decommissioned nuclear reactors is crucial to reduce the volume of intermediate-level waste. Fuel cladding hulls are one of the important parts due to high radioactivity. Their decontamination could possibly enable reclassification as low-level waste. Fuel cladding hulls used in research reactors and being developed for conventional light water reactors are Al-Mg and Fe-Cr-Al alloys, respectively. Therefore, the recovery of these component metals after decontamination is necessary to reduce the volume of highly radioactive waste. Electrochemical approach is often chosen due to its simplicity and effectiveness. Non-aqueous solvents, such as molten salts (MSs) and ionic liquids (ILs), are preferred to aqueous solvents due to the absence of hydrogen evolution. However, MSs and ILs are limited by high temperature and high synthesis cost, along with toxicity issues. Deep eutectic solvents (DESs) are synthesized from a hydrogen bond acceptor (HBA) and donor (HBD) and exhibit outstanding metal salt solubility, wide electrochemical window, good biocompatibility, and economic production process. These characteristics make DES an attractive candidate solvent for economic, green, and efficient electrodeposition compared with aqueous solvents such acids or nonaqueous solvents such as MSs or ILs. In this research, the feasibility of electrodeposition of Al-Mg and Fe-Cr-Al alloys in ChCl:EG, the most common DES synthesized from choline chloride (ChCl) and ethylene glycol (EG), will be tested. A standard three-electrode electrochemical cell with an Au plated working electrode and Al wires for counter and reference electrodes is utilized. Two electrolyte solutions (Al-Mg and Fe-Cr-Al) are prepared by dissolving 100 mM of each anhydrous metal chloride salts (AlCl3, MgCl2, CrCl3, and FeCl2) in ChCl:EG. Cyclic voltammogram (CV) is measured at 5, 10, 15, and 20 mV·s−1 to observe the redox reactions occurring in the solutions. Electrodeposition of each alloy is performed via chronoamperometry at observed reduction potentials from CV measurements. The deposited surfaces and cross-sections are examined by scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) to analyze the surface morphology, cross-section composition, and thickness. Authors anticipate that the presence of different metals will greatly affect the possibility of electrodeposition. It is expected that although all metals are distributed throughout the surface, the morphology, in terms of particle size and shape, would differ depending on metals. Different metals will be deposited by layers of an approximate thickness of a few μm each. This research will illustrate a potential for recovery and electrodeposition of other precious radioactive metals from DES.
        3.
        2016.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Glass-ceramics were developed many years ago and have been applied in many fields such as electronics, chemistry, optics, etc. Much is already known about glass-ceramic technology, but many challenges in glass-ceramic research are still unresolved. Recently, large amounts of slag have steadily increased in the steel industry as by-products. To promote recycling of industrial waste, including steel industry slags, many studies have been performed on the fabrication of basalt-based highstrength glass-ceramics. In this study, we have fabricated such ceramics using various slags to replace high performance castbasalt, which is currently imported. Glass-ceramic material was prepared in similar chemical compositions with commercial cast-basalt through a pyro process using slags and power plant by-product (Fe-Ni slag, converter slag, dephosphorization slag, Fly ash). The properties of the glass-ceramic material were characterized using DTA, XRD, and FE-SEM; measurements of compressive strength, Vicker’s hardness, and abrasion were carefully performed. It is found that the prepared glass-ceramic material showed better performance than that of commercial cast-basalt.
        4,000원
        4.
        2016.04 구독 인증기관·개인회원 무료
        The interest in the role of antioxidants in human health has prompted research in the fields of food science and horticulture to assess fruit and vegetable antioxidants such as ascorbic acid, anthocyanin, flavonoid, phenolic compounds, and total antioxidant activity. Free radicals have been known to cause degenerative diseases: cardiovascular disease, cancer, diabetes, and brain dysfunction. In this study, five cultivars of blueberries (Nelson, Duke, Bluejay, Toro, and Eliot) were harvested in two different maturity stages (unripe and ripe) to evaluate antioxidant activities and anti-dementia activities. Total phenolics and flavonoids of blueberries inthe ripe stage were higher than those in the unripe stage; alsothe total anthocyanin contentswere much higher in ripe fruits thanin unripe fruits. Antioxidant activities of ripen blueberries were greater than unripe fruits, especially; ‘Nelson’ and ‘Toro’ were higher than other cultivars. Total antioxidant activity was highly correlated with total flavonoids (r=0.8568) and phenolics (r=0.9637). However, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition of blueberries showed that unripe fruits were significantly higher than ripe fruits. In conclusion, there were several differences in antioxidant activities and anti-dementia activities of blueberry depending on fruit cultivars and the maturity stage at harvest. Therefore, unripe fruits also have potential health promoting bioactive compounds as a functional foodingredient.
        5.
        2015.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Flat panel display devices are mainly used as information display devices in the 21st century. The worldwide waste flat panel displays are expected at 2-3 million units but most of them are land-filled for want of a proper recycling technology More specifically, rare earth metals of La and Eu are used as fluorescent materials of Cold Cathode Flourscent Lamp(CCFL)s in the waste flat panel displays and they are critically vulnerable and irreplaceable strategic mineral resources. At present, most of the waste CCFLs are disposed of by land-filling and incineration and proper recovery of 80-plus tons per annum of the rare earth fluorescent materials will significantly contribute to steady supply of them. A dearth of Korean domestic research results on recovery and recycling of rare earth elements in the CCFLs prompts to initiate this status report on overseas research trends and noteworthy research results in related fields.
        4,000원
        6.
        2015.05 서비스 종료(열람 제한)
        Due to strong binding, optical clarity, adhesion to many surfaces, toughness and flexibility polyvinyl butyral(PVB) resin films are commonly used in the automotive and architectural application as a protective interlayer in the laminated glass. Worldwide million tons of PVB waste generated from end-of-life automotive associated with various environmental issues. Stringent environmental directive, higher land costs eliminate landfilling option, need a sustainable, environment-friendly technology to recycle these solid wastes. In our current study, we have developed a mechano-chemical separation process to separate PVB resins from glass and have characterized the separated PVB through various techniques, i.e., scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), infrared spectroscopy (IR) and nuclear magnetic resonance spectroscopy (NMR). Feasibility for reuse of these recycled PVB has been investigated. The technology developed in our laboratory is sustainable, environment-friendly, techno-economical feasible process, and capable of mass production (recycling).
        7.
        2015.05 서비스 종료(열람 제한)
        In Korean steel making industry is generating 25 billion tons of slag as industrial by-products per year. Uses of these slags to manufacture high functional abrasive material are of greater feasible option for sustainable development of industry as well as effectively solve the pollution issue associated with these waste. Recycling methods of slag have been actively studied for decades, but most of the slag recycling methods studied are related to low cost building materials. Recently, several combinations of by-products have been used in glass-ceramic manufacturing, mostly the abrasive materials are basalt based glass-ceramic. Using these industrial by-products instead of natural basalt ores, high functional product can be manufactured. This piece of investigation focused on the feasibility study for producing the basalt based glass-ceramic from recycled industrial by-products only, without any natural materials as raw materials. By controlling various process parameters like, mixture ratios of materials, heat treatment for casting, and soaking basalt based glass-ceramic were prepared. The prepared materials were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscope (SEM), thermo-gravimetry and differential thermal analysis (TG-DTA). Excellent material properties were observed.