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        검색결과 9

        1.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The electrochemical properties of a CFX cathode were improved by defluorination of the surface with a N2 plasma and using a silica wafer. Compared to the N2 plasma treatment alone, when the CFX and silica were reacted together, the C-F bonds were modified and the surface was etched efficiently, so defluorination was enhanced. An electrochemical analysis confirmed that Half-cells prepared by treating CFx and silica with nitrogen plasma exhibited a capacity of about 400 mAh/g at 5C. In addition, it was confirmed that the loss of charge transfer was reduced by up to 71% compared to that for pristine CFX. As shown by a GITT analysis, when the CFx and silica were treated with N2 plasma together, the ion conductivity gradually increased due to a decrease in the ion diffusion barriers and the formation of a carbon layer. Therefore, this is a simple and effective way to improve the conductivities of CFX cathode materials with the energy of a N2 plasma and the silica-fluorine reaction.
        4,000원
        2.
        2024.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        It was found in this study that fluorinated microporous carbon aerogels with enhanced hydrophobicity could be successfully prepared by direct fluorination to separate water-in-oil emulsions at high flux. The fluorinated carbon aerogel (F-CA) surface treated by the fluorination method had a water contact angle of 151.2° and could immediately absorb oil. In addition, the unique network structure of F-CA and its hydrophobicity allow surfactant-stabilized water-in-oil emulsions to be effectively and simply separated under gravity without requiring external forces such as vacuum or pressurization. The network structure of F-CAs consists of randomly connected spherical particles that form fluorinated permeation channels, which induce high flux during emulsion separation. The F-CA spherical particles have nanosized pores and high hydrophobicity, which repel and trap water droplets to increase the separation purity. Therefore, F-CA exhibited excellent performance, such as high filtrate purity (up to 99.9954%) and flux (up to 11,710 L/m2h). Furthermore, F-CA reusability was demonstrated as it did not lose its hydrophobicity and maintained its performance even after repeated use. This type of aerogel has great potential to be utilized throughout various environmental fields, including oil remediation.
        4,200원
        3.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The effects of different plasma agent species ( CF4, N2) over the conductivity of CFX cathode material were identified. Both plasma treatments have surface etching effect, while the CF4 plasma treatment has C–F bond modification effect and the N2 plasma treatment has defluorination effect. The changes of surface chemical species and porosity along the plasma agent were elucidated. Moreover, the electrochemical properties of plasma-treated CFX confirmed the effects of plasma treatments. The charge-transfer resistance of plasma-treated CFX was maximum 60.3% reduced than the pristine CFX. The effects of surface chemical modification coupled with etching along the plasma gas agents were compared and identified with their reaction mechanisms.
        4,000원
        4.
        2024.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Fluorine heteroatoms were introduced to increase the limited specific capacitances of electric double-layer capacitors (EDLCs), and the effects of the fluorine atoms were analyzed. To introduce the fluorine, a CF4 plasma treatment was used that introduced the fluorine atoms quickly. Among the fluorine functional groups in the F6-ACA framework, the semi-ionic C–F bonds induced rapid charge transfer and imparted pseudocapacitance. Consequently, we achieved a specific capacitance of 325.68 F/g for the F6-CA sample at 0.5 A/g. By analyzing the contributions of the electric double-layer capacitance and the pseudocapacitance, we determined that the contribution from the pseudocapacitance was 37.57%. A remarkable specific capacitance retention rate of 95.87% was obtained over 1000 charge/discharge cycles with a high current density of 3 A/g. Additionally, the semi-ionic C–F bonds reduced the charge transfer resistance ( Rct) by 36.8%. Therefore, the specific capacitance was improved by the fluorine heteroatoms, and the semi-ionic C–F bonds played a pivotal role in this improvement.
        4,000원
        6.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Canine hyperadrenocorticism, a prevalent endocrine disorder characterized by excessive cortisol production. Notably, hypercoagulability leading to pulmonary thromboembolism (PTE) poses a substantial concern. PTE may be underestimated because of the rapid dissolution of canine thrombi postmortem. However, traditional coagulation assays face challenges in early detection of hypercoagulability. Therefore, this study explored the use of thromboelastography (TEG) as a diagnostic tool for identifying hypercoagulability in dogs with hyperadrenocorticism. A total of 31 dogs visited the Gyeongsang Animal Medical Center between 2018 and 2022, comprising 21 dogs with hyperadrenocorticism and 10 controls who underwent clinical and coagulation analyses. Hyperadrenocorticism was diagnosed using a low-dose dexamethasone stimulation test or adrenocorticotropin hormone stimulation test, and conventional laboratory parameters and coagulation parameters, such as the prothrombin time, activated partial thromboplastic time, fibrinogen, and TEG results, were compared between the groups. Clinical data revealed significantly elevated monocyte, platelet, alanine aminotransferase, alkaline phosphatase, triglyceride, and cholesterol concentrations in dogs with hyperadrenocorticism, which were attributed to excess cortisol secretion (p<0.05). TEG analysis demonstrated significantly decreased K values and increased α and MA values in hyperadrenocorticism dogs (p<0.05), indicating a shortened clotting time and enhanced clot strength, suggestive of hypercoagulability. TEG effectively highlights hypercoagulability in dogs with hyperadrenocorticism and provides valuable insights in predicting blood clot formation. Although predicting clot formation in dogs remains complex owing to multifactorial influences, this study underscores the potential utility of TEG in enhancing such predictions for dogs with hyperadrenocorticism.
        4,200원
        8.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        For the commercialization of hydrogen energy, a technology enabling safe storage and the transport of large amounts of hydrogen is needed. Porous materials are attracting attention as hydrogen storage material; however, their gravimetric hydrogen storage capacity (GHSC) at room temperature (RT) is insufficient for actual use. In an effort to overcome this limitation, we present a N-doped microporous carbon that contains large proportion of micropores with diameters below 1 nm and small amounts of N elements imparted by the nitrogen plasma treatment. The N-doped microporous carbon exhibits the highest total GHSC (1.59 wt%) at RT, and we compare the hydrogen storage capacities of our sample with those of metal alloys, showing their advantages and disadvantages as hydrogen storage materials.
        4,000원
        9.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we investigate the opportunity of using waste tire char as a cathode material for lithium-ion primary batteries (LPBs). The char obtained by carbonizing waste tires was washed with acid and thermally fluorinated to produce CFX. The structural and chemical properties of the char and CFX were analyzed to evaluate the effect of thermal fluorination. The carbon structure of the char was increasingly converted to CFX structure as the fluorination temperature increased. In addition, the manufactured CFX- based LPBs were evaluated through electrochemical analysis. The discharge capacity of the CFX reached a maximum of 800 mAh/g, which is comparable to that of CFX- based LPBs manufactured from other carbon sources. On the basis of these results, the use of waste tire char-based CFX as a cathode material for LPBs is presented as a new opportunity in the field of waste tire recycling.
        4,000원