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        검색결과 949

        121.
        2021.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Sperm cryopreservation is an important method of assisted reproductive techniques and storing genetic resources. It plays a vital role in genetic improvement, livestock industrial preservation of endangered species, and clinical practice. Consequently, the cryopreservation technique is well organized through various studies, especially on Korean native cattle (Hanwoo). However, the cryopreservation technique of Korean native brindled cattle, which is one of the native cattle species in Korea, is not well organized. Therefore, it is necessary to develop a Supplementary Table technique for the cryopreservation of Korean native brindled cattle. For this purpose, it is important to first evaluate the quality of the currently produced cryopreserved sperm of Korean native brindled cattle. In this study, we randomly selected 72 individual Korean native brindled cattle semen samples collected from 8 different region research centers and used them to evaluate sperm functions. We focused on the quality evaluation of cryopreserved Korean native brindled cattle semen following the measurement of motion kinematics, capacitation status, intracellular ATP level, sperm motility, and cell viability. Then, the values of each of the eight groups were derived from various sperm parameters of nine individual samples, including sperm motility, kinematics, cellular motility, and intracellular ATP levels, which were used to compare and evaluate sperm function. Overall, differences in various sperm parameters were observed between most of the research centers. Particularly, the deviations of motility and motion kinematics were high according to the sample. Therefore, we suggest that it is necessary to develop a standard method for the cryopreservation of Korean native brindled cattle semen. We also suggest the need for sperm quality evaluation of the cryopreserved semen of Korean native brindled cattle before using artificial insemination to attain a high fertility rate.
        4,000원
        126.
        2021.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In recent years, various methods of measuring body temperature have been developed using wireless biosensors to facilitate an early detection of pregnancy and parturition in cows. However, there are no studies on real-time monitoring of cattle body temperature throughout pregnancy. Therefore, we investigated the daily mean ruminal temperature in pregnant cows throughout pregnancy using a ruminal bio-capsule sensor and then evaluated the temperature variation between pregnant and non-pregnant cows. In pregnant cows, the mean and standard deviation of ruminal temperature was 38.86 ± 0.17℃. Ruminal temperature in pregnant cows slowly decreased until 180 to 190 days after artificial insemination and after that, the temperature increased dramatically until just before parturition. Furthermore, the means ruminal temperature was significantly different between pregnant and nonpregnant cows. The mean and standard deviation of ruminal temperature were as follows: 38.68 ± 0.01℃ from days 80 to 100, 38.78 ± 0.02℃ from days 145 to 165, 38.99 ± 0.45℃ from days 200 to 220, 39.14 ± 0.38℃ from days 250 to 270 before parturition. Therefore, our results could provide useful data for early detection of pregnancy and parturition in Korean cows.
        4,000원
        127.
        2021.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Since the 2010 foot and mouth (FMD) epidemic, the Korean government has applied a FMD vaccination to pigs. A FMD vaccine is injected to pigs by intramuscular (IM) route. One of the drawbacks in FMD vaccine IM injection is that it would result in an abnormal meat on the injection spot. An abnormal meat due to FMD vaccine IM injection would cause economic loss to pig farmers. An intradermal (ID) injection would be an alternative method for FMD vaccination. The goal of current study was to compare the antibody formation rate between FMD vaccine IM injection and ID injection. The antibody formation rate was measured by the FMD serotype O vaccination percent inhibition (PI) value. In total 350 pigs (175 for FMD vaccine IM injection and 175 for FMD vaccine ID injection) were included in the study. In results, the PI values of FMD vaccine IM injection group were significantly higher than it of FMD vaccine ID injection group. However, the proportions of pigs with PI value was higher than 50, which is a legislative requirement for marketing pigs, for both FMD vaccine IM and ID injection groups at week 20 or 23 were not significantly different. The current results indicated that a FMD vaccine ID injection could be an alternative method of IM injection.
        4,000원
        128.
        2021.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Lightweight and flexible electromagnetic interference (EMI) shielding materials are in great demand for wearable EMI device. In the present work, lightweight and flexible carbon nanotube (CNT)/ferroferric oxide ( Fe3O4) composite film was made through a feasible chemical vapor deposition process for CNT film synthesis, followed by a hydrothermal reduction process for Fe3O4 coating. In the as-prepared composite, CNT film and Fe3O4 particles work as conductive skeleton and strong magnetic particle, respectively. The as-prepared composite film shows a novel EMI shielding effectiveness (SE) of 91 dB in the X-band, a small thickness of 0.09 mm and a low density of 0.86 g/cm3, which is superior to most of the carbonbased EMI materials.
        4,000원
        129.
        2021.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The Ozone Dynamics Investigation Nano-Satellite (ODIN) is a CubeSat design proposed by Chungnam National University as contribution to the CubeSat Competition 2019 sponsored by the Korean Aerospace Research Institute (KARI). The main objectives of ODIN are (1) to observe the polar ozone column density (latitude range of 60 to 80 in both hemispheres) and (2) to investigate the chemical dynamics between stratospheric ozone and ozone depleting substances (ODSs) through spectroscopy of the terrestrial atmosphere. For the operation of ODIN, a highly ecient power system designed for the speci c orbit is required. We present the conceptual structural design of ODIN and an analysis of power generation in a sun synchronous orbit (SSO) using two di erent con gurations of 3U solar panels (a deployed model and a non-deployed model). The deployed solar panel model generates 189.7 W through one day which consists of 14 orbit cycles, while the non-deployed solar panel model generates 152.6 W. Both models generate enough power for ODIN and the calculation suggests that the deployed solar panel model can generate slightly more power than the non-deployed solar panel model in a single orbit cycle. We eventually selected the non-deployed solar panel model for our design because of its robustness against vibration during the launch sequence and the capability of stable power generation through a whole day cycle.
        4,000원
        130.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The aim of this study is to investigate fashion activism that supports sustainability by pursuing social transformation through social media. This is achieved by publicizing the environmental and labor problems of the fashion industry. For this study, a literary survey and netnography were conducted from January 2017 to November 2020. We classified and analyzed environmental and labor issues that could be considered fashion activism on social media. The results are as follows. First, movements for conscious consumption appeared as #haulternative, #fashionourfuture, #SecondHandSeptember, and #wornwear projects. These movements are concerned with buying used goods, re-dressing clothes owned by individuals, and transforming and wearing them with new methods. Second, activism for environmental protection includes #fashionOnclimate by Global Fashion Agenda and Sustainable Fashion Matterz’ #Watermatterz. These movements are directly involved in learning about the seriousness of environmental destruction caused by the fashion industry and participating in environmental protection with critical awareness. Third, the #whomademyclothes and the Clean Clothes Campaign are activism for improving the working environment, and are playing a role in publicizing labor issues by informing the general public about inadequate working conditions linked to the fashion industry. Thus, fashion activism on social media examined in this study can contribute to visualizing chronic problems that hinder sustainable development within the fashion industry.
        4,800원
        131.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To meet the increased performance and cost requirements of commercial supercapacitor, a N and O self-doped hierarchical porous carbon is fabricated via a green and simple self-activation route utilizing leaves of wild hollyhock as raw materials. Comparing to commercial activated carbon, the reported material exhibits some marked merits, such as simple and green fabrication process, low cost, and superior capacitance performance. The specific surface area of the obtained N and O codoped hierarchical porous carbon arrives 954 m2 g−1, and the content of the self-doped nitrogen and oxygen reaches 2.64 at.% and 7.38 at.%, respectively. The specific capacitance of the obtained material reaches 226 F g− 1 while the specific capacitance of the symmetric supercapacitor arrives 47.3 F g− 1. Meanwhile, more than 90.3% of initial specific capacitance is kept under a current density of 20 A g− 1, and no arresting degradation is observed for capacitance after 5000 times cycle, perfectly demonstrating the excellent cycle and rate capability of the obtained material. The obtained N and O co-doped hierarchical porous carbon are expected to be an ideal substitution for commercial activated carbon.
        4,200원
        132.
        2020.12 구독 인증기관 무료, 개인회원 유료
        L-ascorbic acid (L-AA; vitamin C) induces apoptosis in cancer cells. This study aimed to elucidate the molecular mechanisms of L-AA-induced apoptosis in human laryngeal epidermoid carcinoma Hep-2 cells. L-AA suppressed the viability of Hep-2 cells and induced apoptosis, as shown by the cleavage and condensation of nuclear chromatin and increased number of Annexin V-positive cells. L-AA decreased Bcl-2 protein expression but upregulated Bax protein levels. In addition, cytochrome c release from the mitochondria into the cytosol and activation of caspase-9, -8, and -3 were enhanced by L-AA treatment. Furthermore, apoptosis-inducing factor (AIF) and endonuclease G (EndoG) were translocated into the nucleus during apoptosis of L-AA-treated Hep-2 cells. L-AA effectively inhibited the constitutive nuclear factor-κB (NF-κB) activation and attenuated the nuclear expression of the p65 subunit of NF-κB. Interestingly, L-AA treatment of Hep-2 cells markedly activated Akt and mitogen-activated protein kinase (MAPK; extracellular signal-regulated kinase 1/2, p38, and c-Jun N-terminal kinase [JNK]) and and LY294002 (Akt inhibitor), SB203580 (p38 inhibitor) or SP600125 (a JNK inhibitor) decreased the levels of Annexin V-positive cells. These results suggested that L-AA induces the apoptosis of Hep-2 cells via the nuclear translocation of AIF and EndoG by modulating the Bcl- 2 family and MAPK/Akt signaling pathways.
        4,000원
        133.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Naval weapons systems of the Republic of Korea are acquired through the Defense Planning Management System. Recently, acquisition of some naval ships have been delayed, and the causes of the delays have been recognized as inappropriate project management at the Execution Phase. However, we argue that the delay problem in naval ships acquisition should be approached, with due regard for the entire Defense Planning Management System. That is, We should try to investigate from Planning Phase to those of Programming, Budgeting and Execution Phases. Therefore, in this study, we investigated the actual cases of the delay in naval acquisition at all phases of the Defense Planning Management System. Based on the investigation, we tried to identify the naval ship Acquisition Delay Factors and find out the Weights of those factors. As the next step, we calculated the Influence Measures on the naval missions, including the Cost of Naval Capability Gap derived from the delays in acquisition of naval ships. As a final step, we calculated the Acquisition Delay Measures based on the interrelationship between the Acquisition Delay Factors and the Influence Measures. Then we evaluated and analyzed what the results stand for. Finally, we made suggestions for future improvement. The improvement suggestions we made for preventing delay in acquisition of naval ships in this study are as follows. First, we need a shift in perception. It is necessary to measure the Acquisition Delay Factors in acquiring naval ships and manage them from the Planning Phase. Second, resolution must be concerted efforts. All relevant agencies, not just a few, should work together to resolve the problems of acquisition delay. Third, analysis must be based on the accumulation of data. This allows the elaborating of naval ship Acquisition Delay Factors and Delay Measures. If this research method is applied to other military weapons systems in the future, we may be able to not just identify the Acquisition Delay Factors in acquisition of other military weapons systems, but also pursue improvement in those cases.
        4,200원
        134.
        2020.11 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this work, Ag3PO4/In2S3 nanocomposites with low loading of In2S3 (5-15 wt %) are fabricated by two step chemical precipitation approach. The microstructure, composition and improved photoelectrochemical properties of the asprepared composites are studied by X-ray diffraction pattern (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), photocurrent density, EIS and amperometric i-t curve analysis. It is found that most of In2S3 nanoparticles are deposited on the surfaces of Ag3PO4. The as-prepared Ag3PO4/ In2S3 composite (10 wt%) is selected and investigated by SEM and TEM, which exhibits special morphology consisting of lager size substrate (Ag3PO4), particles and some nanosheets (In2S3). The introduction of In2S3 is effective at improving the charge separation and transfer efficiency of Ag3PO4/In2S3, resulting in an enhancement of photoelectric behavior. The origin of the enhanced photoelectrochemical activity of the In2S3-modified Ag3PO4 may be due to the improved charge separation, photocurrent stability and oriented electrons transport pathways in environment and energy applications.
        4,000원
        137.
        2020.11 구독 인증기관·개인회원 무료
        A central focus area of this study is to investigate the distinctive way religion influences consumer behaviour in their consumption of brands by exploring the dynamics that take place when a brand transgression violates a religious norm. Specifically, the Halal consumption context was used in this study, where the brand transgression involved a breach by Halal-certified brands. This study applies the disconfirmation paradigm and posits that a brand transgression involving a violation of a religious norm, results in a unique disconfirmation of expectations that is beyond a consumer-brand relationship. Essentially, the present research explores trust levels and behavioural intentions after a brand transgression and the effectiveness of recovery strategies in mitigating the negative effects of a transgression. A scenario-based experimental approach was used to operationalise this research.