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        검색결과 137

        1.
        2024.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Carbon foam composites containing hollow microspheres, reinforced by carbon nanotubes (CNTs) and montmorillonite (MMT), have been developed as the thermal insulation and EMI shielding layer. The effects of additive amounts of CNTs/ MMT on microstructure and properties of the carbon foam composites were investigated. Results showed that carbon foam composites had hierarchical porous structure, with CNTs and MMT being relatively uniformly dispersed in the composites. The addition of multiscale additives improved the mechanical, electromagnetic shielding effectiveness and thermal insulation properties of carbon foam composites. The composites containing 0.2 wt.% CNTs and 5 wt.% MMT, showed outstanding compressive strength, up to 8.54 MPa, increased by 116% to pure carbon foam. Their electromagnetic shielding effectiveness was as high as 65 dB, increased by 75%. Due to the hierarchical porous structure and MMT’s heat barrier effect, carbon foam composites presented remarkable thermal insulation properties. The minimum thermal conductivity was 0.45 W·m−1·K−1 at 800 °C. Their exceptional thermal protection can also be evidenced by ablation resistance under flame at 1000 °C. Therefore, such multifunctional carbon-based composites are ideal for use in thermal protection.
        4,000원
        2.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, in order to develop an foaming tablet product using yuzu powder, yuzu powder was manufactured using different drying methods such as freeze-drying, 60℃ drying, and 40℃ drying, and then quality characteristics and functionality were analyzed. The naringin content per g of yuzu powder was 8.9 mg for freeze-drying and 8.8 mg for 60℃ drying, and the hesperidin content per g of yuzu powder was highest at 53.6 mg for freeze-drying and 46.2 mg for 60℃ drying. followed by 40℃ drying (41.7 mg). The tyrosinase inhibitory activity of 60℃ dried powder was found to be twice as high as that of freeze dried powder. Accordingly, in order to develop an inner beauty product, foaming tablets were manufactured using hot air dried powder, and the quality characteristics and functional ingredients of the final foaming tablets were investigated. The foaming tablet prepared with yuzu powder content of 10 and 15% showed an inhibitory activity of tyrosinase of 73.7 %, which was 1.6 times higher than that of ascorbic acid (1 mM), which was a positive control, confirming its melanin production inhibition effect.
        4,000원
        3.
        2024.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the aromatic carbon content of epoxy resin (EP) increased via carbon tar pitch (CTP) modification, and the CTP occurred self-polymerization reaction. The carboxyl and hydroxyl groups of CTP and the hydroxyl and carboxyl groups of EP occurred chemical cross-linking reaction. CTP and graphitization treatment promoted EP CF carbon crystal growth. The graphitization degree of pure EP CF and 40 wt% CTP modified EP CF are 8.42% and 44.21%, respectively. With the increase CTP content, the cell size, ligament junction and density of graphitization modified EP CF gradually increased, while the number of pores and cells gradually decreased. The cell size, ligament junction size and density of 40 wt% CTP modified graphitization EP CF increased to 1200 μm, 280 μm and 0.5033 g/cm3, respectively. EP CF exhibits entangling carbon ribbon and isotropic amorphous carbon. The 40 wt% CTP modified EP CF is composed of evenly distributed amorphous resin carbon and graphite domain CTP carbon. The graphitization modified EP CF improved electrical conductivity, and the electrical conductivity of 40 wt% CTP modified EP CF is 126.6 S/m. The compressive strength can be decided by EP carbon strength and its char yield, and graphitization 40 wt% CTP modified EP CF reached 4.9 MPa. This study provides some basis for preparation and application of CTP modified EP CF.
        4,000원
        4.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Self-myofascial release using a foam roller has short-term effects for improving muscle function and joint range of motion (ROM) and reducing delayed onset muscle soreness (DOMS) after exercise. Objectives: The purpose of our study was to examine the muscle physiological changes for each set in self-myofascial release of the hamstring muscles using a foam roller in order to provide basic data for the most effective program composition for improving muscle tension, stiffness, and flexibility of the hamstring muscles. Design: A quasi-experimental clinical trial. Methods: To confirm the effect of self-myofascial release of the hamstring muscles using a foam roller, muscle tone and stiffness of the hamstring muscles were measured. As an intervention method, the study subject performed four sessions of self-myofascial release by moving a foam roller back and forth on the posterior thigh muscle of the right leg. Results: There were statistically significant changes in the stiffness of the biceps femoris and the flexibility of the hamstring muscles. Conclusion: Self-myofascial release with foam rolling is an effective intervention method for increasing hamstring flexibility and ROM, and it is recommended as effective to perform self-myofascial release for three to four sessions to maintain normal muscle tone and stiffness of the hamstring muscles.
        4,000원
        5.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Among the various rehabilitation methods for stroke patients, one method involves the use of vibration. Recently, vibration foam rollers, combining vibration with foam rolling, have been developed and are widely used. Objectives: The purpose of this study was to investigate the effects of vibration foam rolling on ankle range of motion (ROM), and gait speed in patients with stroke. Design: A randomized controlled trial. Methods: Thirty stroke patients volunteered to participate and were randomly assigned to the vibrating foam roller group (n=15) and the non-vibrating foam roller group (n=15). Active dorsiflexion ROM, and 10-meter walk (10MW) were used to evaluate ankle ROM, and gait speed before and after each exercise. The two groups performed a 30-minute foam roller exercise program. The non-vibrating foam roller group performed the same exercise program as the vibrating foam roller group, but without vibration. Results: The within-group change in active dorsiflexion ROM after the exercise was significant for both the vibrating foam roller group and the non-vibrating foam roller group (P<.05). The within-group change in 10MW after the exercise was significant for the vibrating foam roller group (P<.05), while it was not significant for the non-vibrating foam roller group (P>.05). Additionally, there was no significant difference in active dorsiflexion ROM and 10MW between the vibrating foam roller group and the non-vibrating foam roller group (P>.05). Conclusion: This study confirmed that a vibrating foam roller exercise program immediately improves ankle ROM and gait speed in stroke patients.
        4,000원
        6.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Hierarchically porous carbon foam composites with highly dispersed Fe2O3 nanoparticles confined in the foam pores, facilely fabricated by hydrolysis-driven emulsion polymerization strategy. The as-generated acidic conditions of Fe3+ hydrolysis could catalyze the polymerization of phenolic resin, and the carbon-based composite materials containing iron oxides were obtained in situ. The structural characterization results show that HCF@Fe2O3 NPs-2 electrode has the largest specific surface area (549 m2/ g) and pore volume (0.46 cm3/ g). Electrochemical results indicates that typical HCF@Fe2O3 NPs-2 electrode displays good capacitive properties. including high specific capacitance (225 F/g at 0.2 A/g current density). Excellent magnification performance (capacity retention rate 80% as current density increases from 0.2 to 10 A/g). At the same time, HCF@SnO2 NPs was successfully synthesized by replacing hydrolyzed tin tetrachloride with ferric chloride. This study provides a new idea for the preparation of metal oxide–carbon matrix composites, and also highlights the potential of such carbon foams in application of energy storage.
        4,000원
        7.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study explored a method to enhance the drying process usability of local mangoes by producing foam-mat dried powder under varying drying temperatures (50, 60, 70°C) and foam thicknesses (3, 6, 9 mm). The drying process period ranged from 60 to 390 minutes based on the set conditions, with higher temperatures and thinner foams accelerating drying. Powder chromaticity (L*, a*, and b*) demonstrated a declining trend with increasing drying temperature and foam thickness, exhibiting notable variance in chroma values. The water absorption index varied significantly, between 3.08 to 4.24, under different drying conditions, although the water solubility index remained consistent across foam-dried samples. Powder moisture content ranged from 2.53% to 3.83%, with hygroscopicity escalating with temperature and foam thickness. Vitamin C structure was compromised during the hot air drying process, especially at temperatures above 60°C. Electronic nose analysis distinguished foam-dried powder from freeze-dried powder; however, a thicker foam yielded a scent profile closer to that of freeze-dried powder. The findings provide fundamental data on mango foam drying, which is expected to improve processing and storage tech for local mangoes.
        4,000원
        8.
        2023.11 구독 인증기관·개인회원 무료
        Copper hexacyanoferrate (Cu-HCF), which is a type of Prussian Blue analogue (PBA), possesses a specific lattice structure that allows it to selectively and effectively adsorb cesium with a high capacity. However, its powdery form presents difficulties in terms of recovery when introduced into aqueous environments, and its dispersion in water has the potential to impede sunlight penetration, possibly affecting aquatic ecosystems. To address this, sponge-type aluminum oxide, referred to as alumina foam (AF), was employed as a supporting material. The synthesis was achieved through a dip-coating method, involving the coating of aluminum oxide foam with copper oxide, followed by a reaction with potassium hexacyanoferrate (KHCF), resulting in the in-situ formation of Cu-HCF. Notably, Copper oxide remained chemically stable, which led to the application of 1, 3, 5-benzenetricarboxylic acid (H3BTC) to facilitate its conversion into Cu-HCF. This was necessary to ensure the proper transformation of copper oxide into Cu-HCF on the AF in the presence of KHCF. The synthesis of Cu-HCF from copper oxide using H3BTC was verified through X-ray diffraction (XRD) analysis. The manufactured adsorbent material, referred to as AF@CuHCF, was characterized using Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). These analyses revealed the presence of the characteristic C≡N bond at 2,100 cm-1, confirming the existence of Cu-HCF within the AF@CuHCF, accounting for approximately 3.24% of its composition. AF@CuHCF exhibited a maximum adsorption capacity of 34.74 mg/g and demonstrated selective cesium adsorption even in the presence of competing ions such as Na+, K+, Mg2+, and Ca2+. Consequently, AF@CuHCF effectively validated its capabilities to selectively and efficiently adsorb cesium from Cs-contaminating wastewater.
        9.
        2023.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Graphene-derived materials are an excellent electrode for electrochemical detection of heavy metals. In this study, a MnO2/ graphene supported on Ni foam electrode was prepared via ultrasonic impregnation and electrochemical deposition. The resulting electrode was used to detect Pb(II) in the aquatic environment. The graphene and MnO2 deposited on the Ni foam not only improved active surface area, but also promoted the electron transfer. The electrochemical performance towards Pb(II) was evaluated by cyclic voltammetry (CV) and square wave anodic stripping voltammetry (SWASV). The prepared electrode exhibited lower limit of detection (LOD, 0.2 μM (S/N = 3)) and good sensitivity (59.9 μAμM−1) for Pb(II) detection. Moreover, the prepared electrodes showed good stability and reproducibility. This excellent performance can be attributed to the strong adhesion force between graphene and MnO2, which provides compact structures for the enhancement of the mechanical stability. Thus, these combined results provide some technical considerations and scientific insights for the detection of heavy metal ions using composite electrodes.
        4,000원
        10.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: The application of exercise therapy and manual therapy to the thoracic spine is a widely used method of treating neck pain. Nevertheless, studies on the application of foam rollers and vibrating foam rollers to patients with neck pain are lacking. Objectives: To investigated the immediate effects of thoracic spine foam rolling and vibration foam rolling on pain and range of motion (ROM) in patients with chronic neck pain. Design: Randomized crossover trials. Methods: 24 patients with chronic neck pain participated in the study. The study subjects measured pain and ROM. Subjects were divided into vibration foam roller group, foam roller group, and control group. Results: Pain was not significantly different between and within groups (P<.05). There was a significant difference in flexion, extension, left rotation, and right rotation ROM in the vibration foam roller group after intervention (P<.05). There was a significant difference in flexion and extension ROM in the foam roller group after intervention (P<.05). There was a significantly greater increased extension ROM in vibration foam roller and foam roller groups compared with the control group (P<.0167). Conclusion: Thoracic spine foam rolling and vibration foam rolling improve ROM when treating patients with chronic neck pain. Therefore, it is recommended to use it in combination with other treatments
        4,000원
        11.
        2022.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Environmental issues such as global warming due to fossil fuel use are now major worldwide concerns, and interest in renewable and clean energy is growing. Of the various types of renewable energy, green hydrogen energy has recently attracted attention because of its eco-friendly and high-energy density. Electrochemical water splitting is considered a pollution-free means of producing clean hydrogen and oxygen and in large quantities. The development of non-noble electrocatalysts with low cost and high performance in water splitting has also attracted considerable attention. In this study, we successfully synthesized a NiCo2O4/NF electrode for an oxygen evolution reaction in alkaline water splitting using a hydrothermal method, which was followed by post-heat treatment. The effects of heat treatment on the electrochemical performance of the electrodes were evaluated under different heat-treatment conditions. The optimized NCO/NF-300 electrode showed an overpotential of 416 mV at a high current density of 50 mA/cm2 and a low Tafel slope (49.06 mV dec-1). It also showed excellent stability (due to the large surface area) and the lowest charge transfer resistance (12.59 Ω). The results suggested that our noble-metal free electrodes have great potential for use in developing alkaline electrolysis systems.
        4,000원
        12.
        2022.10 구독 인증기관·개인회원 무료
        The dismantlement of the Kori Unit 1 and Wolsong Unit 1 nuclear power plants is scheduled. Since about 40% of the cost of dismantling nuclear power plants is the cost of disposing of generated wastes, it is important to secure recycling technologies. Among them, low and intermediate level radioactive wastes are made of porous filters and adsorbent materials of ceramic foam to remove nuclides such as C-14, I, and Xe generated during nuclear dismantling. In order to remove a large amount of nuclides, physical properties such as a specific surface area and porosity of a ceramic foam filter are important, however when a heat treatment temperature is increased to increase the strength of the filter, the nuclides removal ability is reduced. In order to remove a large amount of nuclides, physical properties such as a specific surface area and porosity of a ceramic foam filter are important, however when a heat treatment temperature is increased to increase the strength of the filter, the nuclides removal ability is reduced. Therefore, in this study, the foam filter performance was improved by applying a sacrificial material to increase the specific surface area and porosity of the ceramic foam filter. The sacrificial material is burned out with polyurethane (PU) of the green filter before the heat treatment temperature to increase the strength of the ceramic foam filter so that it can be maintained as pores, thereby improving the specific surface area and porosity. The sacrificial materials and melting temperature (Tm) reviewed in this study were anthracite (530~660°C), PMMA (160°C), Cellulose acetate (260~270°C), and aluminum particle (660°C), and their effect on the manufacture of foam filters was studied by applying this. The specific surface part and porosity of the foam filter were improved when anthracite and aluminum particle were added, and PMMA and Cellulose acetate, which are relatively low temperature melting points, were burned out at a temperature lower than PU, and thus their physical properties were not greatly affected. The physical properties and specific surface part and porosity of ceramic foam filters manufactured using various sacrificial materials will be discussed.
        13.
        2022.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The recycling of solid waste materials to fabricate carbon-based electrode materials is of great interest for low-cost green supercapacitors. In this study, porous carbon foam (PCF) was prepared from waste floral foam (WFF) as an electrode material for supercapacitors. WFF was directly carbonized at various temperatures of 600, 800, and 1,000 oC under an inert atmosphere. The WFF-derived PCF (C-WFF) was found to have a specific surface area of 458.99 m2/g with multi-modal pore structures. The supercapacitive behavior of the prepared C-WFF was evaluated using a three-electrode system in a 6 M KOH aqueous electrolyte. As a result, the prepared C-WFF as an active material showed a high specific capacitance of 206 F/g at 1 A/g, a rate capability of 36.4 % at 20 A/g, a specific power density of 2,500 W/kg at an energy density of 2.68 Wh/kg, and a cycle stability of 99.96 % at 20 A/g after 10,000 cycles. These results indicate that the C-WFF prepared from WFF could be a promising candidate as an electrode material for high-performance green supercapacitors.
        4,000원
        14.
        2022.05 구독 인증기관·개인회원 무료
        Radioactively contaminated metal components from a nuclear power plant must be decontaminated to reduce the risk of radiation exposure to workers, which can be cleaned using a foam decontamination used to reduce the amount of wastewater significantly. Metal components with a fixed radioactive contamination can be effectively decontaminated using a foam consist of 0.5wt% nonionic surfactant, 0.5 M H2SO4, and 0.2 M Ce(SO4)2. However, strongly acidic wastewater is generated from the decontamination method, which contains a high concentration of the nonionic surfactant and ionic materials with radioactive nuclides. This wastewater must be treated as a stable form. In this study, an integrated process of precipitation and low pressure distillation was evaluated for the treatment of wastewater. It was confirmed that the surfactant and ionic materials were effectively removed from the wastewater through the integrated process.
        15.
        2022.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Preparation of advanced functional materials from agricultural waste by eco-friendly processing route is inevitable for sustainable development. This work demonstrates the development of carbon/silica (C/SiO2) and carbon/silicon carbide (C/ SiC) composite foam monoliths of low thermal conductivity, high EMI shielding performance and reasonable compressive strength from rice husk. The C/SiO2 and C/SiC composite foams are obtained by carbonization and subsequent carbothermal reduction, respectively, of rice husk–sucrose composites consolidated by filter-pressing rice husk powder dispersed in sucrose solutions of various concentrations (300–600 g L− 1). The amorphous nature of silica in C/SiO2 and the presence of β-SiC in C/SiC are evidenced from XRD and TEM analysis. The compressive strength and thermal conductivity are depending on the foam density which is tailored by sucrose solution concentration. The compressive strength in the ranges of 0.32–1.67 and 0.19–1.19 MPa are observed for C/SiO2 and C/SiC foams, respectively, with density in the ranges of 0.26–0.37 and 0.18–0.29 g cm− 3. The C/SiO2 and C/SiC exhibited thermal conductivity in the ranges of 0.150–0.205 W m− 1 K− 1 and 0.165–0.431 W m− 1 K− 1, respectively. The C/SiO2 and C/SiC composite foams show absorption dominated EMI shielding effectiveness in the ranges of 18–38.5 dB and 20–43.7 dB, respectively. The inherent pore channels and corrugated surface structure in rice husk, electrically conducting carbon and dielectric SiO2 and SiC contribute to the total EMI shielding.
        4,500원
        16.
        2022.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Porous mullite-corundum ceramics were prepared using organic foam impregnation method with alumina and silica as raw materials. The influence of alkaline treatment and surfactant modification on polyurethane foam were studied. Effects of sintering process and material composition on porous mullite-corundum ceramics were investigated. The results show that the hang-pulp quantity of polyurethane foam increases with alkaline treatment. After treatment with 3 wt% SDS solution, the hang-pulp quantity of polyurethane foam further improved. Open porosity of sample decreased with elevation of sintering temperature and holding time, and compressive strength of sample showed a trend opposite to the change of porosity. The open porosity of the sample was enhanced by the increase of m(Al2O3/SiO2); the compressive strength decreased with increase of m(Al2O3/SiO2). However, when m(Al2O3/SiO2) was 2.5, the compressive strength of the sample reached 6.23 MPa, and the open porosity of the sample was 80.7 %.
        4,000원
        17.
        2021.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Recently, due to high theoretical capacitance and excellent ion diffusion rate caused by the 2D layered crystal structure, transition metal hydroxides (TMHs) have generated considerable attention as active materials in supercapacitors (or electrochemical capacitors). However, TMHs should be designed using morphological or structural modification if they are to be used as active materials in supercapacitors, because they have insulation properties that induce low charge transfer rate. This study aims to modify the morphological structure for high cycling stability and fast charge storage kinetics of TMHs through the use of nickel cobalt hydroxide [NiCo(OH)2] decorated on nickel foam. Among the samples used, needle-like NiCo(OH)2 decorated on nickel foam offers a high specific capacitance (1110.9 F/g at current density of 0.5 A/g) with good rate capability (1110.9 - 746.7 F/g at current densities of 0.5 - 10.0 A/g). Moreover, at a high current density (10.0 A/g), a remarkable capacitance (713.8 F/g) and capacitance retention of 95.6% after 5000 cycles are noted. These results are attributed to high charge storage sites of needle-like NiCo(OH)2 and uniformly grown NiCo(OH)2 on nickel foam surface.
        4,000원
        20.
        2021.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Although it has been reported that both self-myofascial release (SMR) with foam rolling (FR) and active static hamstring stretching (e.g., jackknife stretching) are effective in improving hamstring flexibility, no study has compared the effects of these exercises. Objectives: To compare the effects of SMR with FR and jack-knife stretching on hamstring flexibility. Design: A Randomized controlled trial. Methods: Subjects with hamstring tightness were divided into the SMR with the FR group (n=12) and the jack-knife stretching group (n=12). Subjects groups performed SMR with FR or jack-knife stretching according to group assignment. To identify changes in hamstring flexibility, the finger-to-floor distance (FFD) test, active knee extension (AKE) test, and passive straight leg raising (PSLR) test were performed at pre- and post-exercise. Results: Significant increases occurred in knee extension angle during the AKE test and hip flexion angle during the PSLR test after exercise in both groups (P<.001). Additionally, FFD and anterior pelvic tilt during the FFD test significantly increased (P<.001); however, we observed no significant interaction and main effects for the groups (P>.05). Conclusion: Both SMR with FR and jack-knife stretching are effective in improving hamstring flexibility in subjects with hamstring tightness.
        4,000원
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