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        검색결과 255

        1.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, Ni-Y2O3 powder was prepared by alloying recomposition oxidation sintering (AROS), solution combustion synthesis (SCS), and conventional mechanical alloying (MA). The microstructure and mechanical properties of the alloys were investigated by spark plasma sintering (SPS). Among the Ni-Y2O3 powders synthesized by the three methods, the AROS powder had approximately 5 nm of Y2O3 crystals uniformly distributed within the Ni particles, whereas the SCS powder contained a mixture of Ni and Y2O3 nanoparticles, and the MA powder formed small Y2O3 crystals on the surface of large Ni particles by milling the mixture of Ni and Y2O3. The average grain size of Y2O3 in the sintered alloys was approximately 15 nm, with the AROS sinter having the smallest, followed by the SCS sinter at 18 nm, and the MA sinter at 22 nm. The yield strength (YS) of the SCS- and MA-sintered alloys were 1511 and 1688 MPa, respectively, which are lower than the YS value of 1697 MPa for the AROS-sintered alloys. The AROS alloy exhibited improved strength compared to the alloys fabricated by SCS and conventional MA methods, primarily because of the increased strengthening from the finer Y2O3 particles and Ni grains.
        4,000원
        2.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Captive breeding and reintroduction are crucial strategies for conserving endangered species populations. However, fish raised in predator-free environments, show a lack of recognition of predationrelated stimuli such as chemical and visual signals. It is critical to recognize chemical signals from injured conspecifics, also known as alarm signals, and the order or shape of predators to indicate the spread of predation risk in the habitat. We conducted a laboratory experiment to determine and adjust the optimal exposure period to induce appropriate anti-predator behavior response to different types of stimuli (Chemical, Visual and Chemical+Visual) for the endangered species Microphysogobio rapidus. Our results demonstrate that predator avoidance behavior varies depending on the types of stimuli and the duration of predation risk exposure. First, the results showed captive-breed M. rapidus show lack of response against conspecific alarm signal (Chemical cue) before the predation risk exposure period and tend to increase response over predation risk exposure time. Second, response to predator (visual cue) tend to peak at 48 hours cumulative exposure, but show dramatic decrease after 72 hours cumulative exposure. Finally, response to the mixed cue (Chemical+visual) tend to peak prior to the predation risk exposure period and show reduced response during subsequent exposure periods. This experiment confirms the lack of responsiveness to conspecific alarm signals in captive-bred M. rapidus and the need for an optimal nature behavior enhancement program prior to release of endangered species. Furthermore, responsiveness to predator visual signal peak at 48 hours cumulative exposure, suggest an optimal predation risk exposure period of up to 48 hours. Key words: predator cognition, captive breeding, chemical signal, visual signal, endangered
        4,000원
        3.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study analyzed the monitoring results of fishways at 16 weirs constructed on four large Rivers to provide data helpful for the operation and management of fishways. The average utilization rate of the fishways at the weirs was confirmed to be 64.9%. When comparing the dominant species in the mainstream and fishway monitoring results, differences were observed in 9 weirs (56.3%). This indicated that the species prevalent in the mainstream were not necessarily the ones most frequently using the fishways. The average number of individuals using the fishways per day was 336. When classifying the fish species using the fishway by life type, 92.3% were primary freshwater fish, and migratory species accounted for only 5.6%. Analysis based on the season of fishway usage revealed that an average or higher number of fish species used the fishways from May to October, with the highest number of individual users occurring from June to August. Between May and July, 80% of the fish species using the fishways were in their spawning period, while during other season, less than 40% were species that move during the spawning period. The fishways that showed a significant alignment between the spawning period and the fishway passage period were Rhinogobius brunneus, Leiocassis nitidus, Squalidus chankaensis tsuchigae, Pseudogobio esocinus, Acheilognathus rhombeus, and Pungtungia herzi, in that order. When comparing the fishway monitoring results of the Gangjeong-Goryeong Weir and the Dalseong Weir with the upper part water level of the weir, both the number of fish species and individuals using the fishway showed positive correlations with the upper part water level of the weir. This suggests that a higher water level of the weir increases the inflow discharge within the fishway, leading to increased use by fish (number of individuals in Gangjeong-Goryeong Weir, P<0.001; number of species in Dalseong Weir, P<0.05). This study summarized and analyzed the results of fishway monitoring at 16 weirs built on four large Rivers, considering fishway efficiency, operation and management, monitoring period, and regulation of water level in the upper part of the weir. It is thought that this will help understand the status of fish use in fishways on large River and aid the construction, operation, and management of fishways in the future.
        4,800원
        7.
        2023.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Opuntia ficus-indica (OFI), or Pricky Pear Cactus, is effective in cough, fever, pain and anti-inflammatory action, and asthma. This study aims to investigate the effect of OFI stem extract on the respiratory system of animal models induced by ovalbumin (OVA) and fine dust (PM10) and to analyze the indicator substances of OFI stem extract. In the OFI stem 50% ethanol extract (OFI-50E) administration group, the number of immune cells and inflammatory cytokines in the lungs and BAL decreased to a similar level to the positive control group administered with dexamethasone. In addition, OVA-specific IgE and airway hyper-reactivity (AHR) were significantly reduced. Also, the deposition of PM10 observed through staining of lung tissue was clearly reduced in the OFI-50E 200 mg/kg administration group. The anti-inflammatory mechanism in the lung was found to obstruct the production of inflammatory cytokines by impeding the NF-kB and MAPK pathways through the inhibition of IRAK-1 active cells. The main component of OFI stem 50% ethanol extract was identified to be narcissin. According to the study results, OFI is expected to be a respiratory health functional food.
        4,300원
        8.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Small ponds, which exhibit unstable succession pattern of plankton community, are less well studied than large lakes. Recently, the importance of small ponds for local biodiversity conservation has highlighted the necessity of understanding the dynamics of biological community. In the present study, we collected zooplankton from three small reservoirs with monthly basis and analyzed their seasonal dynamics. To understand the complicated zooplankton community dynamics of small reservoirs, we categorized zooplankton species into four groups (LALF Group, Low Abundance Low Frequency; LAHF Group, Low Abundance High Frequency; HALF Group, High Abundance Low Frequency; HAHF Group, High Abundance High Frequency) based on their occurrence pattern (abundance and frequency). We compared the seasonal pattern of each group, and estimated community diversity based on temporal beta diversity contribution of each group. The result revealed that there is a relationship between groups with the same abundance but different occurrence frequencies, and copepod nauplii are common important component for both abundance and frequency. On the other hand, species included with LALF Group throughout the study period are key in terms of monthly succession and diversity. LALF Group includes Anuraeopsis fissa, Hexarthra mira and Lecane luna. However, groups containing species that only occur at certain times of the year and dominate the waterbody, HALF Group, hindered to temporal diversity. The results of this study suggest that the species-specific occurrence pattern is one key trait of species determining its contribution to total annual biodiversity of given community.
        4,800원
        9.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        SOCS3, a suppressor of cytokine signaling 3, is known as a negative regulator of various cytokines and a tumor suppressor gene in human tumors. This study aimed to investigate the role of SOCS3 in oral squamous cell carcinoma (OSCC) and its impact on epithelial-mesenchymal transition (EMT) in OSCC cells. Although SOCS3 is recognized as a negative regulator of various cytokines and a tumor suppressor gene in human tumors, its specific effects on OSCC remain poorly understood. For the assessment of SOCS3 expression in OSCC, the UALCAN website and TCGA data were used to evaluate its expression in head and neck cancer. Additionally, immunohistochemical staining was conducted to determine the SOCS3 expression specifically in OSCC. The findings indicated a significant decrease in SOCS3 expression in tumor tissue compared to that in normal tissues. To investigate the enhancement of SOCS3 expression in OSCC cancer cell lines, IL6 treatment was administered to MC3 cells. However, no significant differences were observed in cell viability, wound healing assay, and invasion assay. Conversely, the transfection of SOCS3 siRNA into OSCC cells led to a notable increase in cell viability and statistically significant increases in wound healing and invasion assays. These results suggest that SOCS3 plays a crucial role in cell viability and EMT in OSCC, thereby contributing to oral carcinogenesis. Further research is necessary to elucidate the precise role of SOCS3 in OSCC.
        4,300원
        13.
        2023.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Taxillus yadoriki (Siebold) Dancer is a parasitic plant that grows on camellia trees and is common on Jeju Island. The branches of T. yadoriki have long been used to treat various diseases, including hypertension, diabetes mellitus, viral infections, and arthritis. Although recent studies reported that T. yadoriki has anticancer effects in various human cancer cell lines, including lung cancer, the exact molecular mechanisms supporting its anticancer effects are not well understood. This study aims to assess the anticancer effect of the methanol extract of T. yadoriki branches (METY) on mucoepidermoid carcinoma (MEC) cell lines (MC3 cells and YD15 cells) and explore its mechanism of action. Inhibitory activity of MEC cell proliferation was assessed using the CCK-8 assay. The mechanism of the anticancer effect on METY-treated MC3 cells and YD15 cells was evaluated with Hoechst 33342 stain and Western blot. After treating MC3 cells and YD15 cells with METY for 48 hours, the cytotoxicity of MC3 and YD15 cells increased, and nuclear fragmentation increased in both METY-treated MEC cells. Caspase-3 and cleaved PARP activation demonstrated apoptosis of METY-treated MEC cells. Cell proliferation inhibition with METY was alleviated in METY-treated MEC cells pretreated with zVAD-FMK, supporting the cell proliferation inhibition effect by apoptosis. METY-induced apoptosis in MEC cells occurs through MAP kinase pathways such as p38 and pAkt. MEC cell. METY-induced apoptosis of MEC cells occurs via the p38 and pAkt MAPK pathways. Therefore, METY may be a promising anticancer candidate for the MEC therapeutic strategy.
        4,000원
        14.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study carried out from March 2021 to October 2021 in the upper part (St. 1) and middle part (St. 2) section of Yongsu stream, a branch of the Geum river, using PIT telemetry to understand the movement patterns and habitat characteristics of Odontobutis interrupta, a Korean endemic species. O. interrupta collection was used kick net (5×5 mm) and fish trap (5×5 mm). After collecting fish, PIT tag insertion was performed immediately in the site. Reader (HPR Plus Reader, biomark, USA) and portable Antenna (BP Plus Portable Antenna, biomark, USA) were used for detection of fish to monitoring the tagged O. interrupta. As a result of PIT telemetry applied to 70 individuals, mean movement distance was 36.5 (SE, ±6.6) m. There was a significant difference between total length and movement distance (P≤0.05). O. interrupta was mainly identified in average water depth, 36.2±1.9 cm, average water velocity, 0.03±0.07 m s-1 and average distance from watershed, 4.4±0.3 m. Extent of rock used for habitat was varied from 32 to 4,000 cm2. There was no statistical difference between the area of the first selected rock and the area of the after selected rock (P>0.05). but there was significant difference between total length and the area of the rock except for detection before 24 hours (P<0.01). Therefore, to restore the habitat, it is considered necessary to create various substrate structures by providing various habitat environments (water depth, flow rate, stone, etc.) for each individual size.
        4,200원
        15.
        2022.12 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 용제를 전혀 사용하지않고 UV경화가 가능한 나노 실버 페이스트를 개발하였다. 무용제(solvent-free) 타입으로 개발한 나노 실버 페이스트의 점도 및 점탄성 측정하였다. 그리고 스크린인쇄로 패턴을 인쇄한 후에 UV 경화로 전극도막을 형성시켰다. 형성된 전극도막의 전도성, 연필경도, 접착력에 대해서 평가하였다. 또한 전극 도막 을 광 소결하여 전도성을 평가하였다. 마지막으로 전극도막의 경화특성은 TGA 및 FT-IR로 평가하였다. 이러한 결 과를 정리하면 UV경화만 시켰을 경우에는 전도성, 접착력, 경화특성에 대해서는 Paste(3)이 가장 우수하였다. 그러 나 광소결 후에는 Paste(1)이 가장 우수한 전도성을 얻을수있었다. 그 이유는 10nm 실버 파우더를 사용한 것이 소 결 특성이 가장 우수했기 때문이라고 판단된다.
        4,000원
        16.
        2022.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To optimize initial cooling conditions, forced-air cooling was applied to freshly harvested oak mushrooms at 2 levels (0oC for 30 minutes, at 0oC for 1 hour) followed by room cooling at 3 levels (-3oC for 1 day, 0oC for 1 day, 3oC for 1 day). After initial cooling, the oak mushrooms were packaged with PVC film, then held in a storage room at 1oC for 6 weeks. Quality characteristics and percentage marketability were then investigated. As a control, Mushrooms were placed in storage with no initial cooling. The quality factors impacting marketability of fresh oak mushrooms were color change and appearance of decay. Off-odor did not occur or developed only slightly, so it did not affect oak mushroom quality within 6 weeks of low temperature storage. In all treatment groups, the shelf life in which 100% marketability was maintained was up to 3 weeks. At week 5, percent marketability of the 3 treatment groups 1 hour room cooling treatment at 0°C, 1 hour forced air cooling, and control was 100%. 80% In the group that underwent 30 min forced air cooling retained 80% marketability, and the group exposed to 1 day in room cooling at -3oC retained 86.7% marketability. At week 6 of 1oC storage, the marketability ratio was 80% in the 1 day room cooling at 0oC group, 66.7% in the 1 day room cooling at 3oC group, 46.7% in the 1 hour forced air cooling group, and 33% or less in all other treatment groups. Therefore, the most suitable initial cooling parameter to extend shelf-life of oak mushrooms is 1 day of in room cooling at 0oC immediately after harvest.
        4,000원
        17.
        2022.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The first step is to determine the principal dimensions of the design ship, such as length between perpendiculars, beam, draft and depth when accomplishing the design of a new vessel. To make this process easier, a database with a large amount of existing ship data and a regression analysis technique are needed. Recently, deep learning, a branch of artificial intelligence (AI) has been used in regression analysis. In this paper, deep learning neural networks are used for regression analysis to find the regression function between the input and output data. To find the neural network structure with the highest accuracy, the errors of neural network structures with varying the number of the layers and the nodes are compared. In this paper, Python TensorFlow Keras API and MATLAB Deep Learning Toolbox are used to build deep learning neural networks. Constructed DNN (deep neural networks) makes helpful in determining the principal dimension of the ship and saves much time in the ship design process.
        4,000원
        20.
        2022.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Estuary is important in terms of biodiversity because it has the characteristics of transition waters, created by the mixing of fresh- and seawater. The estuarine water circulation provides a variety of habitats with different environments by inducing gradients in the chemical and physical environment, such as water quality and river bed structure, which are ultimately the main factors influencing biological community composition. If the water circulation is interrupted, the loss of brackish areas and the interception of migration of biological communities will lead to changes in the spatial distribution of biodiversity. In this study, among the sites covered by the Estuary Aquatic Ecosystem Health Assessment, we selected study sites where changes in biodiversity can be assessed by spatial gradient from the upper reaches of the river to the lower estuarine area. The α-, γ- and β-diversity of diatom, benthic macroinvertebrates, and fish communities were calculated, and they were divided into open and closed estuary data and compared to determine the trends in biodiversity variation due to estuarine circulation. As results, all communities showed higher γ-diversity at open estuary sites. The benthic macroinvertebrate community showed a clear difference between open and closed estuaries in β-diversity, consequently the estuarine transects were considered as a factor that decreases spatial heterogeneity of their diversity among sites. The biodiversity trends analyzed in this study will be used to identify estuaries with low γ- and β-diversity by community, providing a useful resource for further mornitoring and management to maintain estuarine health.
        4,800원
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