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        검색결과 111

        1.
        2024.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Synthesis of extremely competent materials is of great interest in addressing the energy storage concerns. Manganese oxide nanowires ( MnO2 NWs) are prepared in situ with multiwall carbon nanotubes (MWCNT) and graphene oxide (GO) using a simple and effective hydrothermal method. Powder XRD, Raman and XPS analysis are utilized to examine the structural characteristics and chemical state of composites. The initial specific discharge capacity of pure MnO2 NWs, MnO2 NWs/ MWCNT and MnO2 NWs/rGO composites are 1225, 1589 and 1685 mAh/g, respectively. The MnO2 NWs/MWCNT and MnO2 NWs/rGO composites showed stable behavior with a specific capacity of 957 and 1108 mAh/g, respectively, after 60 cycles. Moreover, MnO2 NWs/rGO composite sustained a specific capacity of 784 mAh/g, even after 250 cycles at a current density of 1 A/g showing outstanding cycling stability.
        4,200원
        4.
        2023.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Structural inversion refers to the reverse reactivation of extensional faults that influence basin shortening accommodated by contractional faults or folds. On the Korean peninsula, Miocene inversion structures have been found, but the Cretaceous rocks on Geoje Island may have undergone inversion as early as the Upper Cretaceous. To evaluate the structural inversion on Geoje Island, located on the eastern side of South Korea, and to determine the effects of preexisting weakness zones, field-based geometric and kinematic analyses of faults were performed. The lithology of Geoje Island is dominated by hornfelsified shale, siltstone, and sandstone in the Upper-Cretaceous Seongpori formation. NE and NW-oblique normal faults, conjugate strike-slip (NW-sinistral transpressional and E-W-dextral transtensional) faults, and NE-dextral transpressional faults are the most prominent structural features in Geoje Island. Structural inversion on Geoje Island was evidenced by the sinistral and dextral transpressional reactivation of the NW and NE-trending oblique normal faults respectively, under WNW-ESE/NW-SE compression, which was the orientation of the compressive stress during the Late Cretaceous to Early Cenozoic.
        4,900원
        6.
        2021.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We investigate 20 post-coronal mass ejection (CME) blobs formed in the post-CME current sheet (CS) that were observed by K-Cor on 2017 September 10. By visual inspection of the trajectories and projected speed variations of each blob, we nd that all blobs except one show irregular \zigzag" trajectories resembling transverse oscillatory motions along the CS, and have at least one oscillatory pattern in their instantaneous radial speeds. Their oscillation periods are ranging from 30 to 91 s and their speed amplitudes from 128 to 902 kms􀀀1. Among 19 blobs, 10 blobs have experienced at least two cycles of radial speed oscillations with di erent speed amplitudes and periods, while 9 blobs undergo one oscillation cycle. To examine whether or not the apparent speed oscillations can be explained by vortex shedding, we estimate the quantitative parameter of vortex shedding, the Strouhal number, by using the observed lateral widths, linear speeds, and oscillation periods of the blobs. We then compare our estimates with theoretical and experimental results from MHD simulations and uid dynamic experiments. We nd that the observed Strouhal numbers range from 0.2 to 2.1, consistent with those (0.15{3.0) from uid dynamic experiments of blu spheres, while they are higher than those (0.15{0.25) from MHD simulations of cylindrical shapes. We thus nd that blobs formed in a post-CME CS undergo kinematic oscillations caused by uid dynamic vortex shedding. The vortex shedding is driven by the interaction of the outward-moving blob having a blu spherical shape with the background plasma in the post-CME CS.
        4,000원
        10.
        2019.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The normal feeding approach of goats might be due to their precise anatomical and physiological characteristics of entity, which permit them to be highly selective, to eat legume silages and wild green grass. This review has been designed to consider the grazing behavior, fodder selection, and feed composition of goats. Various herbs and corns consumed by goats have numerous nutritive resources. Based on the general herbaceous intake activities and behavior of goats, they prefer wild grass such as grass grown in the steep hills than soft grass. Because the digestion capacity of cellulose feed has higher digestion level compared to other non-ruminants within rumen and it is advantageous to use wild forest or mountain grass which comprises high proportion of cellulose feed for goat. In South Korea, there are abundant feed resources for goats because of occupying large areas of mountains. Thus, goat production and feeding costs could be reduced if plants are used from the wild forest as a feed for goats relative to grassland grazing. Also, it is expected to contribute in improvement of goat farming with harmonious relationship between the grassland and wild forest while satisfying animal welfare and physiological desires of livestock.
        4,000원
        12.
        2018.11 구독 인증기관·개인회원 무료
        To preserve the superior genetic resources and restore the endangered species, Somatic cell nuclear transfer (SCNT) has been used widely. In Korea, the research of dog cloning has made outstanding achievements including the production of the world`s first cloned dog. Sapsaree (Sapsalgae), the representative dog of Gyeongsan-si was designated as a Korea natural monument (No. 368). This male dog used in this study has azoospermia due to unknown cause. In this study, the aim was to confirm the cause of infertility in the cell donor dog and to evaluate the reproduction potential of dog cloning using infertile male dog by SCNT. First, to confirm the infertility of the cell donor dog, the reproductive history and the testis were evaluated. The breeding histology was not recorded in individual document. In histopathology, the Sertoli cell tumor was confirmed in biopsy of the cell donor dog after death. But, these tumors are predominantly in older dogs. Second, we produced the cloned dogs with the somatic cells of the infertile dog and the appearance was similar with the cell donor dog. Also, microsatellite analysis confirmed the genetic relationship between the cell donor and clone dogs. Third, the potential breeding capacity of the cloned dog was confirmed. In T4 assay, the normal dog (same age with cloned dogs), cell donor dog, and cloned dogs was investigated. The cell donor dog with azoospermia had very low T4 level, and cloned dogs showed higher level of T4 than normal dogs. In CASA, There was no significant difference in sperm motor ability between normal dogs and cloned dogs. As a result, cloned dogs produced by SCNT had no problem regarding the reproductive function of the testis. In AI experiment, the semen of clone dogs was used to fertilize a natural female bitch and was diagnosed pregnancy by ultrasonography. In total, 7 puppies were born by normal delivery (male: 3, female: 4). In conclusion, this study confirmed that the reproduction problem of non-genetic infertility can generate a normal descendant by SCNT. Also, the first successful research to restore infertile dogs was completed. Furthermore, SCNT would be useful for the restoration of endangered species and application of superior traits.
        15.
        2018.05 구독 인증기관·개인회원 무료
        The aged asphalt binder included in RAP due to the oxidative aging, repeated vehicle load, climate process affects to the recycled asphalt mixture property and performance (stripping, port hole and premature cracking initiation) after paving. The rejuvenator commonly is used to recover the aged binder in hot mix asphalt (HMA) containing RAP; the effect of rejuvenator in HMA had been proven according to many studies for over the past several decades. Also, there are many methods for using RAP in asphalt mixture in aspects of HMA, cold asphalt mixture (CMA) and worm mix asphalt mixture (WMA), and a foamed asphalt mixture is one of them. Employing the foamed asphalt manufacturing technology, the content of RAP in recycled asphalt mixture can be increased more. The objectives of this study are to evaluate of rejuvenator influence on foamed asphalt mixture using 100% RAP based on strength change of test sample and stiffness change of recovered binder from RAP and specimen. As the results, when rejuvenator was added to make foamed asphalt mixture, MS and ITS values decreased clearly as compared with the foamed asphalt mixture without rejuvenator use. The use of rejuvenator up to 6% showed a tendency of the decrease of strength and stability remarkably. The use of rejuvenator over 6% did not decrease the strength and stability. DSR test results, the use of rejuvenator in making a foamed asphalt mixture using 100% RAP showed a recovery effect of the foamed asphalt mixture. And recovered binder from the specimen that was made adding the 6, 12 and 18% rejuvenator showed lower stiffness obviously compared to the recovered binder from RAP adding same dosage of rejuvenator.
        16.
        2017.11 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Self-cleaning and photocatalytic TiO2 thin films were prepared by a facile sol-gel method followed by spin coating using peroxo titanic acid as a precursor. The as-prepared thin films were heated at low temperature(110 °C) and high temperature (400 °C). Thin films were characterized by X-ray diffraction(XRD), Field-emission scanning electron microscopy(FESEM), UVVisible spectroscopy and water contact angle measurement. XRD analysis confirms the low crystallinity of thin films prepared at low temperature, while crystalline anatase phase was found the for high temperature thin film. The photocatalytic activity of thin films was studied by the photocatalytic degradation of methylene blue dye solution. Self-cleaning and photocatalytic performance of both low and high temperature thin films were compared.
        4,000원
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