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        검색결과 132

        42.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A new discrete bis-dithiolene complex, [ PPh4]2[Zn(DMED)2] (1; DMED = 1,2-dicarbomethoxy-1,2-dithiolate) with sulfurbased radical character was synthesized and structurally characterized. Complex 1 is stable and exhibits a square planar geometry around the zinc metal. 1 forms nanospheres through a one-pot water-induced self-assembly in a mixture of solvents (acetonitrile–water). These nanospheres were further decorated with water-soluble carbon nanotubes (wsCNTs) through hydrogen bonding between the peripheral –COOCH3 groups of 1 and surfacial carboxyl groups of wsCNTs to assemble into a spherical nanocomposite. The as-prepared nanocomposite showed fluorescence emissions in visible region due to the separation of energy states of the nanospheres assisted by wsCNTs, suggesting the future possibilities of these new materials for use in biomedical application.
        4,000원
        43.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The present study was designed to determine the effect of barn or cycle of grazing on changes of biochemical metabolites in prepartum and changes of milk composition in postpartum of dairy cows. For this purpose, a total of sixteen 25 months old Holstein primiparous dairy cows were allocated in two groups (n=8) with an average body weight of 571.61 ± 35.30 kg (Barn) and 578.10 ± 39.20 kg (Grazing). The study was conducted from June 2018 to October 2018. Results revealed that barn raised dairy cows had a higher increase in their serum albumin and calcium level on day 14 prepartum. However, the level of palmitic acid, saturated fatty acid increased significantly, and the level of fat, oleic acid, γ-linoleic acid, arachidonic acid and unsaturated fatty acids decreased significantly in barn raised dairy cow’s milk on day 14 postpartum. There were no significant differences observed with respect to all other biochemical metabolites, fatty acids and minerals between barn raised and cycle grazing dairy cows during prepartum and postpartum. Our study results could serve to a better understanding of barn raised cow with respect to changes of biochemical metabolites in prepartum and changes of milk composition, fatty acids and minerals content in grazing dairy cows in postpartum for estimating their physiological status.
        4,000원
        44.
        2019.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Given the important status of students as major stakeholders of the National English Curriculum, this study investigated specific needs of curriculum-takers for an English curriculum and compared the results with analyses of curriculum evaluation from curriculum-completers. We implemented a needs assessment survey targeting 68 elementary school students (current curriculum-takers) and an evaluation survey targeting 27 high school students (curriculum-completers) in Korean EFL context. Results showed similarities between students’ needs and evaluation in terms of the ideal time for starting English education and time allotments. However, we found significant gaps between the two groups in several domains related to their specific goals of learning English. While the current curriculum-takers showed a high motivation to learn English for both instrumental purposes and integrative purposes, the curriculum-completers were strongly biased toward instrumental purposes. Our findings provide useful insight into curriculum development and improvement for seeking educational effectiveness in EFL settings. This study also provides helpful resources for conducting needs and evaluation analyses.
        6,400원
        47.
        2019.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present an analysis of the chemical abundances and kinematics of six low-mass dwarf stars, previously claimed to be candidate hypervelocity stars (HVSs). We obtained moderate-resolution ($R\sim6000$) spectra of these stars to estimate the abundances of several chemical elements (Mg, Si, Ca, Ti, Cr, Fe, and Ni), and derived their space velocities and orbital parameters using proper motions from the \gaia\ Data Release 2. All six stars are shown to be bound to the Milky Way, and in fact are not even considered high-velocity stars with respect to the Galactic rest frame. Nevertheless, we attempt to characterize their parent Galactic stellar components by simultaneously comparing their element abundance patterns and orbital parameters with those expected from various Galactic stellar components. We find that two of our program stars are typical disk stars. For four stars, even though their kinematic probabilistic membership assignment suggests membership in the Galactic disk, based on their distinct orbit l properties and chemical characteristics, we cannot rule out exotic origins as follows. Two stars may be runaway stars from the Galactic disk. One star has possibly been accreted from a disrupted dwarf galaxy or dynamically heated from a birthplace in the Galactic bulge. The last object may be either a runaway disk star or has been dynamically heated. Spectroscopic follow-up observations with higher resolution for these curious objects will provide a better understanding of their origin.
        4,500원
        54.
        2018.05 구독 인증기관·개인회원 무료
        This research evaluates the applicability of ponded ash in the production of backfill material. From various ponded ash/sand ratios, cement, and air foam conditions, test specimens were developed to investigate many engineer properties of backfill material. Then, the falling weight deflectometer and excavation tests were carried out to determine the behavior of the material in the actual testbed. The test results suggested that all mixtures achieved optimal flowability performance with acceptable stiffening time. It is indicated that the compressive strength increased as ponded ash and cement contents increased, but the strength decreased with an increase in air-foam content or number of freeze-thaw cycles. From the testbed results, it was found that utilizing 100% ponded ash in the production of backfill material is very promising for sustainable development purpose.
        55.
        2017.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present a study of the inexplicit connection between radio jet activity and γ-ray emission of BL Lacertae (BL Lac; 2200+420). We analyze the long-term millimeter activity of BL Lac via interferometric observations with the Korean VLBI Network (KVN) obtained at 22, 43, 86, and 129 GHz simultaneously over three years (from January 2013 to March 2016); during this time, two γ-ray outbursts (in November 2013 and March 2015) can be seen in γ-ray light curves obtained from Fermi observations. The KVN radio core is optically thick at least up to 86 GHz; there is indication that it might be optically thin at higher frequencies. To first order, the radio light curves decay exponentially over the time span covered by our observations, with decay timescales of 41185 days, 352±79 days, 310±57 days, and 283±55 days at 22, 43, 86, and 129 GHz, respectively. Assuming synchrotron cooling, a cooling time of around one year is consistent with magnetic field strengths B ∼ 2 μT and electron Lorentz factors γ ∼ 10 000. Taking into account that our formal measurement errors include intrinsic variability and thus over-estimate the statistical uncertainties, we nd that the decay timescale  scales with frequency τ ν - 0.2. This relation is much shallower than the one expected from opacity effects (core shift), but in agreement with the (sub-)mm radio core being a standing recollimation shock. We do not find convincing radio flux counterparts to the γ-ray outbursts. The spectral evolution is consistent with the `generalized shock model' of Valtaoja et al. (1992). A temporary increase in the core opacity and the emergence of a knot around the time of the second -ray event indicate that this γ-ray outburst might be an `orphan' are powered by the `ring of fi re' mechanism.
        4,300원
        58.
        2017.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to examine the effect of corn (Zea mays L.) - soybean (Glycine max L.) silage prepared by intercropping method on the nutritive value of the silage, in vitro rumen fermentation characteristics, dry matter degradability, as well as milk yield and milk composition of dairy cows. In a couple of experiments intercropped corn-soybean silage (CSBS) was compared with corn silage (CS) and/or Italian ryegrass hay (IRG). Numerically, CSBS had higher crude protein, ether extract, and lactic acid contents compared to CS. In vitro rumen fermentation analysis demonstrated that up to a 24-h incubation period, both CS and CSBS showed higher total gas production, ammonia N concentration, and dry matter degradability compared to IRG (p<0.05). The investigation on animals was conducted in a commercial dairy farm located in Gyeongju, South Korea, employing 42 Holstein cows that were divided into 2 group treatments: CS and CSBS in a completely randomized design. Although no significant difference was observed in milk yield, animals fed on CSBS showed significantly higher milk protein (p<0.05) and milk fat content (p<0.01), compared to animals fed on CS. Taken together, our findings indicate that corn-soybean silage that is cultivated, harvested, and prepared through intercropping can improve the protein content of the silage, and can also enhance in vitro rumen fermentation, dry matter degradability, and performance of dairy cattle.
        4,000원
        59.
        2017.09 구독 인증기관 무료, 개인회원 유료
        To determine the effect of the tumor necrosis factor-α (TNF-α) in odontoclast formation, we administrated a TNF-α inhibitor in rats with diabetes rats with periodontitis. The rats included in the study were divided into three groups: control rats without diabetes or periodontitis (the C group), rats with periodontitis and diabetes (the PD group), and rats with periodontitis and diabetes treated by infliximab, the TNF inhibitor (the PD+infliximab group). The PD and PD+ infliximab groups received intravenous administrations of streptozotocin (STZ, 50 mg/kg) to induce diabetes. After 7 days of STZ injections, the mandibular first molars were ligatured to induce periodontitis. The PD+infliximab group was intrapenitoneally administrated by infliximab (5 mg/kg). On days 3 and 20 after the ligature administration, odontoclast formation along root surfaces was evaluated by tartrate resistant acid phosphatase (TRAP) staining and cathepsin K immunohistochemistry. On day 3, the number of TRAP- and cathepsin K-positive cells increased more so in the PD group than in the C group. The PD+infliximab group showed a lower number of positive cells than the PD group. There was no difference in all the groups on day 20. On day 3, the cathepsin-K positive multinucleated and mononucleated cells were higher in the PD group than in the C group. The number of cathepsin-K positive multinucleated cells was lower in the PD+infliximab group than in the PD group. The PD group showed more cathepsin K-positive cells in the furcation and distal surfaces than the c group. The Cathepsin K-positive cells of the PD+infliximab group were lower than that of the PD group in furcation. These results suggest that TNF-α stimulates odontoclast formation in diabetes with periodontitis.
        4,000원
        60.
        2017.07 구독 인증기관·개인회원 무료
        Emotional sharing of brand has a power of connecting brand and consumer brand and consumer by transcending rational reason.
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