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        검색결과 165

        2.
        2021.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Even in an era where 8-meter class telescopes are common, small telescopes are considered very valuable research facilities since they are available for rapid follow-up or long term monitoring observations. To maximize the usefulness of small telescopes in Korea, we established the SomangNet, a network of 0.4{1.0 m class optical telescopes operated by Korean institutions, in 2020. Here, we give an overview of the project, describing the current participating telescopes, its scienti c scope and operation mode, and the prospects for future activities. SomangNet currently includes 10 telescopes that are located in Australia, USA, and Chile as well as in Korea. The operation of many of these telescopes currently relies on operators, and we plan to upgrade them for remote or robotic operation. The latest SomangNet science projects include monitoring and follow-up observational studies of galaxies, supernovae, active galactic nuclei, symbiotic stars, solar system objects, neutrino/gravitational-wave sources, and exoplanets.
        4,600원
        6.
        2019.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Environmental pollution remains a considerable health risk source all over the world; however, hazards are usually higher in developing countries. Iraq has long been suffering from the problem of pollution and how to treat pollution. Photocatalytic degradation has turned out to be most productive process for dye degradation. In this investigation, Rhodamine B (RhB), dye has been selected for degradation under visible light illumination. To address this issue, we fabricate erbium trioxide nanoparticles (Er2O3/NPs). Erbium trioxide nanoparticles are prepared and utilized for photo-catalytic degradation. The characterization of Er2O3/NPs is described and confirmed by utilizing of XRD (X-ray diffraction) and SEM (Scanning Electron Microscopy). The average size of Er2O3 nanoparticles is observed to be 16.00 nm. Er2O3/NPs is investigated for its ability of photo-catalytic degradation through certain selected parameters such as concentration and time. The methodological results show that the synthesized Er2O3/NPs is a good photo-catalytic for Rhodamine degradation.
        4,000원
        7.
        2019.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Intensive Monitoring Survey of Nearby Galaxies (IMSNG) is a high cadence observation program monitoring nearby galaxies with high probabilities of hosting supernovae (SNe). IMSNG aims to constrain the SN explosion mechanism by inferring sizes of SN progenitor systems through the detection of the shock-heated emission that lasts less than a few days after the SN explosion. To catch the signal, IMSNG utilizes a network of 0.5-m to 1-m class telescopes around the world and monitors the images of 60 nearby galaxies at distances D < 50 Mpc to a cadence as short as a few hours. The target galaxies are bright in near-ultraviolet (NUV) with MNUV < - 18.4 AB mag and have high probabilities of hosting SNe (0.06 SN yr-1 per galaxy). With this strategy, we expect to detect the early light curves of 3.4 SNe per year to a depth of R  19:5 mag, enabling us to detect the shock-heated emission from a progenitor star with a radius as small as 0.1 R . The accumulated data will be also useful for studying faint features around the target galaxies and other science projects. So far, 18 SNe have occurred in our target fi elds (16 in IMSNG galaxies) over 5 years, confi rming our SN rate estimate of 0.06 SN yr-1 per galaxy.
        4,200원
        8.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, an empirical relationship between the energy band gap of multi-walled carbon nanotubes (MWCNTs) and synthesis parameters in a chemical vapor deposition (CVD) reactor using factorial design of experiment was established. A bimetallic (Fe-Ni) catalyst supported on CaCO3 was synthesized via wet impregnation technique and used for MWCNT growth. The effects of synthesis parameters such as temperature, time, acetylene flow rate, and argon carrier gas flow rate on the MWCNTs energy gap, yield, and aspect ratio were investigated. The as-prepared supported bimetallic catalyst and the MWCNTs were characterized for their morphologies, microstructures, elemental composition, thermal profiles and surface areas by high-resolution scanning electron microscope, high resolution transmission electron microscope, energy dispersive X-ray spectroscopy, thermal gravimetry analysis and Brunauer-Emmett-Teller. A regression model was developed to establish the relationship between band gap energy, MWCNTs yield and aspect ratio. The results revealed that the optimum conditions to obtain high yield and quality MWCNTs of 159.9% were: temperature (700ºC), time (55 min), argon flow rate (230.37 mL min–1) and acetylene flow rate (150 mL min–1) respectively. The developed regression models demonstrated that the estimated values for the three response variables; energy gap, yield and aspect ratio, were 0.246 eV, 557.64 and 0.82. The regression models showed that the energy band gap, yield, and aspect ratio of the MWCNTs were largely influenced by the synthesis parameters and can be controlled in a CVD reactor.
        4,000원
        11.
        2018.10 구독 인증기관·개인회원 무료
        First Mover Advantage is already well known. It is when a company gains a position in a certain market or industry, or when it establishes a strong entry barriers through a distribution channel or a monopoly of resources. It is a concept that has been attracting attention for a long time in marketing and strategy. However, although it is possible for the starter to enjoy these various benefits, it is also true that there is a corresponding price. Therefore, the risks and costs that the starter may bear, and thus the relative benefits enjoyed by the latter, can be significant. Late Mover Advantage and so on. The fact that latecomers can enjoy a variety of benefits as well as the profits of the starters is an important consideration that must be taken into account by many companies considering entry into the market. In general, there is a very high risk of overinvestment in technology and market uncertainty. For example, China has skipped wired networks and went wireless, and many African countries have skipped wired communications and built infrastructure for wireless communications. In other words, companies that hastened to invest in fixed-line facilities in order to preoccupy the African telecom market are in a state of failure rather than expecting the interests of the starters. Another thing is that the starter has to bear more risks and costs than the latter, such as the uncertainty of demand, the risk of changing consumer preferences, and the cost of training new consumers. Also, because imitation is generally less costly than development, a latecomer entering through imitation may be in a better position if patents or other technical defenses are not available. Especially, if latecomers have excellent management ability and financial power such as excellent marketing ability, it is relatively easy to catch up with the first candidate.
        12.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        At the Bank of Korea, capital stock statistics were created by the PIM (perpetual inventory method) with fixed capital formation data. Asset classifications also included 2 categories in residential buildings, 4 non-residential buildings, 14 constructions, 9 transportation equipment, 28 machinery, and 2 intangible fixed assets. It is the Korean government accounting system which is developed much with the field of the national accounts including the valuation, but until 2008 it was consistent with single-entry bookkeeping. Many countries, including Korea, were single-entry bookkeeping, not double-entry bookkeeping which can be aggregated by government accounting standard account. There was no distinction in journaling between revenue and capital expenditure when it was consistent with single-entry bookkeeping. For example, we would like to appropriately divide the past budget accounts and the settlement accounts data that have been spent on dredging into capital expenditure and revenue expenditure. It, then, tries to add the capital expenditure calculated to FCF (fixed capital formation), because revenue expenditure is cost for maintenance etc. This could be a new direction, especially, in the estimation of capital stock by the perpetual inventory method for infrastructure (SOC, social overhead capital). It should also be noted that there are differences not only between capital and income expenditure but also by other factors. How long will this difference be covered by the difference between the ‘new series’ and ‘old series’ methodologies? In addition, there is no large difference between two series by the major asset classification level. If this is treated as a round-off error, this is a problem.
        4,000원
        13.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Although the 1997 Raw Data of the National Wealth Statistical Survey (South Korea) is timely 20-year-old data, it is meaningful as a benchmarking in the capital stock estimations of Korea, which is estimated by PIM (permanent inventory method). In the case of machinery/equipment, it is the data that can analyze in depth the changes in the industrial structure of Korea. In the case of ASL (average service life) which has economic concept, since the change of ASL is not so large, ASL yielded by the Raw Data of the 1997 National Wealth Statistical Survey is meaningful as reference value for the ASL estimated by the Bank of Korea and the National Statistical Office. As you know Japan has changed its service life due to changes in its industrial structure. However, many of its assets are still used for the years indicated in Showa (before 1989). The same trend with other countries such as Japan. However, the United States is constantly devoted to assessing the useful ASL and value of assets by distinguishing between the Hulten-Wykoff models and those not. Korea has also benchmarked the useful ASL of the United States and Japan when it conducted its own survey every 10 years by due diligence until 1997. In this study, the ‘constraint’ Iowa curve estimation by the Raw Data of the 1997 National Wealth Statistical Survey is based on the age records of the assets and the maximum age of the assets appropriately derived. And then we made modified Iowa curve by smoothing. From this modified one, we suggested ASL by asset. After 1997, the vintage disposal data directly were collected by the National Statistical Office with Oh Hyun Seung, Cho Jin Hyung, in order to estimate the useful ASL. Since then, the B/S team of the Economic and Statistics Bureau of the Bank of Korea has been working on a new concept of content training.
        4,300원
        14.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, a correlation between execution of quality management activities and their results was verified by applying the Malcolm Baldrige model (hereafter referred to as the MB model) as a quality management performance measurement indicator for small and medium enterprises (SMEs) in South Korea. To achieve this goal, we need to determine whether the categorical requirements in the MB model are recognized consistently in SMEs, as a prerequisite. To this end, factor analysis was conducted for measurement variables in each category, which revealed that the process indicator was made up of six factors and the outcome indicator was made up of five factors, like those configured in the MB model. This result can be interpreted to mean that the requirements in each category of the MB model were well produced and recognized consistently throughout SMEs in South Korea. In addition, the analysis of causality between the process indicator (quality management activities) and the outcome indicator (management results) showed high causality between them. Although the quality management levels of SMEs in South Korea are inferior to those of conglomerates or other national quality award-winning companies, this study is significant in that the causality between quality management activities and results was verified, since this study targeted SMEs in South Korea as the target of investigation. Thus, it is empirically proven that the MB model can contribute to improved management results for SMEs in Korea.
        4,000원
        17.
        2017.05 구독 인증기관·개인회원 무료
        The purpose of this study was to investigate the effect of estrus synchronization to altrenogest regumate (progesterone), PMSG/hCG, and artificial insemination (AI) on galectin-3, FGF-9 gene and protein expression. The morpho-metrical parameters of the endometrium and the number of corpora lutea (CL) were recorded. RNA was isolated from endometrial, oviduct and ovary tissues of non-synchronized (Control; n = 7) and AI synchronized (regumate, PMSG/hCG; n = 7) sows. The total number of CL was higher (P<0.05) in pigs treated with regumate/PMSG/hCG. The content of gelactin-3 and FGF-9 mRNA in pre-embryonic development stages increased on particular days, in control and studied in regumate/PMSG/hCG administered pigs. Gelactin-3 and FGF-9 were affected by regumate/PMSG/hCG treatment in the both pre-embryonic development stages (P<0.001, P<0.05) and encdometrial tissue (P<0.001, P<0.01). The regumate/PMSG/hCG treatment resulted in elevated expression of gelactin-3 (P<0.001) and FGF-9 (P<0.005) in oviduct and ovary tissues in comparison to control sows. Moreover, oviduct amount of gelectin-3 mRNA was higher in regumate/PMSG/hCG sows in comparison to the control group (P<0.05), whereas, expression characteristics of gelactin-3 and FGF-9 were investigated by hematoxylin and eosin stained and immunohistochemical staining. The results showed that galectin-3 and FGF-9 were significantly shown in the endometrium, oviduct and ovary tissues of the regumate/PMSG/ hCG. Presented data show that exogenous hormones administration can affect gene and protein expression in the sow reproductive tract.
        18.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The recent updates of the North Ecliptic Pole deep (0.5 deg2, NEP-Deep) multi-wavelength survey covering from X-ray to radio-wave is presented. The NEP-Deep provides us with several thousands of 15 μm or 18 μm selected galaxies, which is the largest sample ever made at these wavelengths. A continuous filter coverage in the mid-infrared wavelength (7, 9, 11, 15, 18, and 24 μm) is unique and vital to diagnose the contributions from starbursts and AGNs in the galaxies out to z=2. The new goal of the project is to resolve the nature of the cosmic star formation history at the violent epoch (e.g. z=1{2), and to find a clue to understand its decline from z=1 to present universe by utilizing the unique power of the multiwavelength survey. The progress in this context is brie y mentioned.
        4,000원
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