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        검색결과 1,538

        1.
        2024.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the mid-eastern part of the Yellow Sea, large-scale shelf ridges originated from erosion on sand-mud successions that have been presently eroded by strong tidal currents. A three-layered in situ geoacoustic model is provided down to 50 m for the subbottom sedimentary succession of a 45 m water depth using the Hamilton method. The succession is divisible into two-type units of Type-A and Type-B using high-resolution seismic profiles with a deep-drilled YSDP-104 core of 44.0 m in depth below the seafloor. Type-A unit mainly comprises sandy or gravelly sediments, whereas Type-B unit mostly consists of tidal muddy sediments with some thinner sand beds. P-wave speed values are positively compatible with the mean grain size and sediment type of the core sediments. For actual modeling, the geoacoustic property values of the models were compensated to in situ depth values below the seafloor. The detailed geoacoustic model contributes to simulating sound transmission through the sedimentary successions in erosional shelf ridges of variable geoacoustic properties distributed in shallow-water environments of the mid-eastern Yellow Sea.
        4,200원
        3.
        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
        4.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper explores the potential application of carbon nanotubes (CNTs) in the construction industry, as CNTs can effectively serve as nano-fillers, bridging the voids and holes in cement structures. However, the limited dispersibility of CNTs in water necessitates the use of dispersing agents for achieving uniform dispersion. In this study, two kinds of cement superplasticizers, polycarboxylate ether (PCE) and sulfonated naphthalene formaldehyde (SNF) were employed as dispersing agents to improve the interfacial affinity between CNTs and cement, and to enhance the strength of the cement nanocomposites. Contact angle experiments revealed that the utilization of PCE and SNF effectively addressed the interface issues between CNTs and cement. As a result, the cement nanocomposite with a CNT to PCE ratio of 1:2 exhibited an approximately 6.6% increase in compressive strength (73.05 MPa), while the CNT:SNF 1:2 cement composite showed a 4.7% increase (71.72 MPa) compared to plain cement (68.52 MPa). In addition, the rate of crack generation in cement nanocomposites with CNTs and dispersing agents was found to be slower than that of plain cement. The resulting cement nanocomposites, characterized by enhanced strength and durability, can be utilized as safer materials in the construction industry.
        4,600원
        5.
        2024.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this work, we investigated the photo-degradation performance of MnO2-SiC fiber-TiO2 (MnO2-SiC-TiO2) ternary nanocomposite according to visible light excitation utilizing methylene blue (MB) and methyl orange (MO) as standard dyes. The photocatalytic physicochemical characteristics of this ternary nanocomposite were described by X-ray diffraction (XRD), scanning electron microscopy (SEM), tunneling electron microscopy (TEM), ultraviolet-visible (UV-vis), diffuse reflectance spectroscopy (DRS), electrochemical impedance spectroscopy (EIS), photocurrent and cyclic voltammogram (CV) test. Photolysis studies of the synthesized MnO2-SiC-TiO2 composite were conducted using standard dyes of MB and MO under UV light irradiation. The experiments revealed that the MnO2-SiC-TiO2 exhibits the greatest photocatalytic dye degradation performance of around 20 % with MB, and of around 10 % with MO, respectively, within 120 min. Furthermore, MnO2-SiC-TiO2 showed good stability against photocatalytic degradation. The photocatalytic efficiency of the nanocomposite was indicated by the adequate photocatalytic reaction process. These research results show the practical application potential of SiC fibers and the performance of a photocatalyst composite that combines these fibers with metal oxides.
        4,000원
        6.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Despite its anticancer activity, cisplatin exhibits severe testicular toxicity when used in chemotherapy. Owing to its wide application in cancer therapy, the reduction of damage to normal tissue is of imminent clinical need. In this study, we evaluated the effects of catechin hydrate, a natural flavon-3-ol phytochemical, on cisplatin-induced testicular injury. Methods: Type 2 mouse spermatogonia (GC-1 spg cells) were treated with 0-100 μM catechin and cisplatin. Cell survival was estimated using a cell proliferation assay and Ki-67 immunostaining. Apoptosis was assessed via flow cytometry with the Dead Cell Apoptosis assay. To determine the antioxidant effects of catechin hydrate, Nrf2 expression was measured using qPCR and CellROX staining. The anti-inflammatory effects were evaluated by analyzing the gene and protein expression levels of iNOS and COX2 using qPCR and immunoblotting. Results: The 100 μM catechin hydrate treatment did not affect healthy GC-1 spg cells but, prevented cisplatin-induced GC-1 spg cell death via the regulation of anti-oxidants and inflammation-related molecules. In addition, the number of apoptotic cells, cleaved-caspase 3 level, and BAX gene expression levels were significantly reduced by catechin hydrate treatment in a cisplatin-induced GC-1 spg cell death model. In addition, antioxidant and anti-inflammatory marker genes, including Nrf2 , iNOS, and COX2 were significantly downregulated by catechin hydrate treatment in cisplatintreated GC-1 cells. Conclusions: Our study contributes to the opportunity to reintroduce cisplatin into systemic anticancer treatment, with reduced testicular toxicity and restored fertility.
        4,000원
        7.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        From 2020, Korean Animal and Plant Quarantine Agency has reset the withdrawal time (WT) for veterinary drugs typically used in livestock in preparation for the introduction of positive list system (PLS) program in 2024. This study was conducted to reset the MRL for tiamulin (TML) in broiler chickens as a part of PLS program introduction. Forty-eight healthy Ross broiler chickens were orally administered with TML at the concentration of 25 g/L (TML-1, n=24) and 50 g/L (TML-2, n=24) for 5 days through drinking water, respectively. After the drug treatment, tissue samples were collected from six broiler chickens at 1, 2, 3 and 5 days, respectively. According to the previously established analysis method, residual TML concentrations in poultry tissues were determined using LC-MS/MS. In TML-1, TML in all tissues was detected less than LOQ at 2 days after drug treatment. In TML-2, TML in liver and kidney was detected more than LOQ at 2 days after treatment. According to the European Medicines Agency’s guideline on determination of withdrawal periods, withdrawal periods of TML-1 and TML-2 in poultry tissues were established to 0 and 2 days, respectively. In conclusion, the estimated WT of TML in poultry tissues is shorter than the current WT recommendation of 5 days for TML in broiler chickens.
        4,000원
        8.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: This study focused on reproductive traits in Hanwoo cattle, specifically the environmental factors affecting gestation length and birth weight. Methods: The records of 1,540 cows calved at the Hanwoo Research Institute from 2015 to 2023 were examined. This study analyzed two populations, linebreeding Hanwoo (LBH) and general Hanwoo (GH), with all cows undergoing estrus synchronization and artificial insemination. The R software was used to compare the differences between the two populations and analyze the environmental factors affecting each trait. Results: The results showed that the average gestation length for LBH was 283.28 ± 5.93 days, which was significantly shorter than that of the GH, which had an average of 285.63 ± 6.21 days (p < 0.001). The average birth weight of LBH calves was 25.10 ± 3.69 kg, significantly lighter than GH calves, which weighed 27.26 ± 4.11 kg on average (p < 0.001). Analysis of environmental factors revealed significant differences in the gestation length of LBH based on dam parity, year, and season of calving. However, no significant differences were observed based on calf sex. For LBH, birth weight showed significant differences based on dam parity, year of calving, and sex of the calf, but not the season of calving. In GH, gestation length varied with dam parity and calving season, but not with calving year or calf sex. The GH birth weight showed differences based on dam parity, year of calving, and calf sex, but not the season of calving. Conclusions: Reproductive traits in the Hanwoo cattle industry are economically vital but are heavily influenced by environmental factors due to their low heritability. An accurate evaluation of the genetic potential of these traits requires an analysis of the environmental factors affecting them. The results of this study serve as foundational data for predicting the potential for genetic improvement in the gestation length and birth weight of Hanwoo cattle.
        4,000원
        9.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: In healthy dentin conditions, odontoblasts have an important role such as protection from invasion of pathogens. In mammalian teeth, progenitors such as mesenchymal stem cells (MSCs) can migrate and differentiate into odontoblast-like cells, leading to the formation of reparative dentin. For differentiation using stem cells, it is crucial to provide conditions similar to the complex and intricate in vivo environment. The purpose of this study was to evaluate the potential of differentiation into odonto/ osteoblasts, and compare co-culture with/without epithelial cells. Methods: MSCs and epithelial cells were successfully isolated from dental tissues. We investigated the influences of epithelial cells on the differentiation process of dental pulp stem cells into odonto/osteoblasts using co-culture systems. The differentiation potential with/without epithelial cells was analyzed for the expression of specific markers and calcium contents. Results: Differentiated odonto/osteoblast derived from dental pulp tissue-derived mesenchymal stem cells with/without epithelial cells were evaluated by qRT-PCR, immunostaining, calcium content, and ALP staining. The expression of odonto/ osteoblast-specific markers, calcium content, and ALP staining intensity were significantly increased in differentiated cells. Moreover, the odonto/osteogenic differentiation capacity with epithelial cells co-culture was significantly higher than without epithelial cells co-culture. Conclusions: These results suggest that odonto/osteogenic differentiation co-cultured with epithelial cells has a more efficient application.
        4,000원
        10.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The increase in the use of artificial intelligence (AI) in the workplace has introduced changes to traditional working environments. However, these are changes not only to employee productivity but also to how employees feel and think about their work. Based on prior research that has suggested connections between employees’ perceptions of AI and their emotions and thoughts at work, the present study tested a moderated mediation model in which the perception of AI opportunity is indirectly related to job insecurity via employee hope, with tenure as a moderator. Data obtained from 290 Korean full-time employees illustrated that the perception of AI opportunity was negatively related to job insecurity through hope acting as a mediator. In addition, this indirect relationship was found to be dependent on the moderating role of tenure. Specifically, at lower levels of tenure, the aforementioned indirect relationship was statistically significant, but at higher levels of tenure, this indirect relationship was no longer found to be statistically significant. The implications, limitations, and future research directions of this study are discussed.
        4,600원
        11.
        2024.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, laser-induced graphene oxide (LIGO) was synthesized through a facile liquid-based process involving the introduction of deionized (DI) water onto polyimide (PI) film and subsequent direct laser irradiation using a CO2 laser (λ = 10.6 μm). The synthesized LIGO was then evaluated as a sensing material for monitoring changes in humidity levels. The synthesis conditions were optimized by precisely controlling the laser scribing speed, leading to the synthesis of LIGO with different structural characteristics and varying oxygen contents. The increased number of oxygen-containing functional groups contributed to the hydrophilic properties of LIGO, resulting in a superior humidity sensing capabilities compared with laser-induced graphene (LIG). The LIGO-based sensors outperformed LIG-based sensors, demonstrating approximately tenfold higher sensing responsivity when detecting changes at each humidity level, along with 1.25 to 1.75 times faster response/recovery times, making LIGO-based sensors more promising for humidity-monitoring applications. This study demonstrated laser ablation in a renewable and natural precursor as an eco-friendly and energy-efficient approach to directly synthesize LIGO with controllable oxidation levels.
        4,500원
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