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        검색결과 61

        1.
        2023.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Porous carbons are considered promising for CO2 capture due to their high-pressure capture performance, high chemical/ thermal stability, and low humidity sensitivity. But, their low-pressure capture performance, selectivity toward CO2 over N2, and adsorption kinetics need further improvement for practical applications. Herein, we report a novel dual-templating strategy based on molten salts (LiBr/KBr) and hydrogen-bonded triazine molecules (melamine–cyanuric acid complex, MCA) to prepare high-performance porous carbon adsorbents for low-pressure CO2. The comprehensive investigations of pore structure, microstructure, and chemical structure, as well as their correlation with CO2 capture performance, reveal that the dual template plays the role of porogen for multi-hierarchical porous structure based on supermicro-/micro-/meso-/ macro-pores and reactant for high N/O insertion into the carbon framework. Furthermore, they exert a synergistic but independent effect on the carbonization procedure of glucose, avoiding the counter-balance between porous structure and hetero-atom insertion. This enables the preferred formation of pyrrolic N/carboxylic acid functional groups and supermicropores of ~ 0.8 nm, while retaining the micro-/meso-/macro-pores (> 1 nm) more than 60% of the total pore volume. As a result, the dual-templated porous carbon adsorbent (MG-Br-600) simultaneously achieves a high CO2 capture capacity of 3.95 mmol g− 1 at 850 Torr and 0 °C, a CO2/ N2 (15:85) selectivity factor of 31 at 0 °C, and a high intra-particle diffusivity of 0.23 mmol g− 1 min− 0.5 without performance degradation over repeated use. With the molecular scale structure tunability and the large-scale production capability, the dual-templating strategy will offer versatile tools for designing high-performance carbon-based adsorbents for CO2 capture.
        4,300원
        2.
        2020.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        스리랑카는 채소의 주년 생산에 적합한 기후를 갖고 있는 열대국가이다. 열대, 아열대 채소의 재배면적은 전체 농지(105,062 ha)의 약 3%이다. 지난 50년 동안 스리랑카에서 채소 육종에 관한 체계적인 연구가 이루어졌고 채소 부문은 지속적으로 증가하였다. 하지만 채소 육종, 재배 및 가공과 관련된 기술이 선진국에 비해 많이 뒤떨어져 있는 형편이다. 전통 육종법을 통해 개발된 다양한 농업적 형질을 가진 품종이 현재까지 스리랑카의 채소 생산에 이용되고 있지만 생명공학적 방법을 접목한 채소 품종 육종법의 중요성이 점차로 부각되고 있다. 본 논문은 스리랑카에서 중요한 채소 작물인 토마토, 고추류, 콩류, 가지 및 여주의 육종과 품종 현황을 소개하고 향후 스리랑카 육종 전망에 대해 논의하였다.
        4,000원
        4.
        2017.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The Korea Astronomy and Space Science Institute plans to develop a coronagraph in collaboration with National Aeronautics and Space Administration (NASA) and to install it on the International Space Station (ISS). The coronagraph is an externally occulted one-stage coronagraph with a field of view from 3 to 15 solar radii. The observation wavelength is approximately 400~nm, where strong Fraunhofer absorption lines from the photosphere experience thermal broadening and Doppler shift through scattering by coronal electrons. Photometric filter observations around this band enable the estimation of 2D electron temperature and electron velocity distribution in the corona. Together with a high time cadence ($<$12~min) of corona images used to determine the geometric and kinematic parameters of coronal mass ejections, the coronagraph will yield the spatial distribution of electron density by measuring the polarized brightness. For the purpose of technical demonstration, we intend to observe the total solar eclipse in August 2017 with the filter system and to perform a stratospheric balloon experiment in 2019 with the engineering model of the coronagraph. The coronagraph is planned to be installed on the ISS in 2021 for addressing a number of questions (e.g., coronal heating and solar wind acceleration) that are both fundamental and practically important in the physics of the solar corona and of the heliosphere.
        4,200원
        5.
        2016.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We report the characterization of a massive (mp = 3:91:4Mjup) microlensing planet (OGLE- 2015-BLG-0954Lb) orbiting an M dwarf host (M = 0:33  0:12M ) at a distance toward the Galactic bulge of 0:6+0:4 􀀀0:2 kpc, which is extremely nearby by microlensing standards. The planet-host projected separation is a?  1:2AU. The characterization was made possible by the wide- eld (4 deg2) high cadence (􀀀 = 6 hr􀀀1) monitoring of the Korea Microlensing Telescope Network (KMTNet), which had two of its three telescopes in commissioning operations at the time of the planetary anomaly. The source crossing time t = 16 min is among the shortest ever published. The high-cadence, wide- eld observations that are the hallmark of KMTNet are the only way to routinely capture such short crossings. High-cadence resolution of short caustic crossings will preferentially lead to mass and distance measurements for the lens. This is because the short crossing time typically implies a nearby lens, which enables the measurement of additional e ects (bright lens and/or microlens parallax). When combined with the measured crossing time, these e ects can yield planet/host masses and distance.
        4,000원
        6.
        2015.09 KCI 등재 구독 인증기관·개인회원 무료
        We have been performing daily VLBI monitoring of the ux density of Sagittarius (Sgr) A* at 22 GHz from February 2013 to August 2014 using a sub-array of the Japanese VLBI Network (JVN). The purpose of this monitoring is to explore the ux density variability at daily time resolution for a period longer than one year with the G2 cloud approaching. The ux density of Sgr A* is basically stable during the observational period, though there are some small variations. The average and scattering range are consistent with the previously observed values. We have observed no strong are of Sgr A* although it is near the expected peri-center passing.
        7.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We present a kinematic study of the parsec-scale radio jet in OJ 287, one of the most studied BL Lac objects, during γ-ray ares, to explore the relation between parsec-scale radio jet activity and γ-ray emission. The 22-GHz light curve of OJ 287 show three obvious are events around 2011 May, 2011 October, and 2012 March. The second radio are occurred during the γ-ray aring period, and the third radio are seemed to precede the γ-ray are by one month. One jet component moved outward with respect to the core component with an apparent superluminal speed (~ 11c) from 2010 November to 2011 November. Then it changed direction, moving apparently inward in 2011 November, when the γ-ray are occurred. The observed apparent inward motion of the jet at 22 GHz could be caused by a new jet component, unresolved at 22 GHz, in the innermost region.
        3,000원
        8.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We use ALLWISE data release W1- and W2-band epoch photometry collected by the Wide-Field Infrared Survey Explorer (WISE) to determine slopes of the period-luminosity relations for RR Lyrae stars in 15 globular clusters in the corresponding bands. We further combine these results with V- and K-band photometry of Galactic field RR Lyrae stars to determine the metallicity slopes of the log PF - [Fe/H]-MK, log PF - [Fe/H]-MW1, and log PF - [Fe/H]- MW2 period-metallicity-luminosity relations. We infer the zero points of these relations and determine the kinematical parameters of thick-disk and halo RR Lyraes via statistical parallax, and estimate the RR Lyrae-based distances to 18 Local-Group galaxies including the center of the Milky Way.
        4,000원
        10.
        2012.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We have performed a systematic study of interstellar dust grains in various environments of galaxies. AKARI has revealed the detailed properties of dust grains not only in star-forming regions but also in regions not relevant to star formation, some of which are found not to follow our old empirical knowledge. Because of its unique capabilities, AKARI has provided new knowledge on the processing of large grains and polycyclic aromatic hydrocarbons (PAHs). For example, we detect PAHs from elliptical galaxies, which show unusual spectral features and spatial distributions, demonstrating importance of material processing in the interstellar space. We find that copious amounts of large grains and PAHs are flowing out of starburst galaxies by galactic superwinds, which are being shattered and destroyed in galactic haloes. We discover evidence for graphitization of carbonaceous grains near the center of our Galaxy, providing a clue to understanding the activity of the Galactic center. We review the results obtained from our AKARI program, focusing on the processing of carbonaceous grains in various environments of galaxies.
        4,000원
        12.
        2011.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The aim of this study was to evaluate the post-thawed characteristics of leopard cat semen. In this experiment, semen was collected from two leopard cats (A and B) at wild animal center in Seoul Grand Park in Korea. After collection, the sperms were washed with D-PBS and diluted by the freezing medium (Irvine science, USA) and stored in liquid nitrogen. The post-thawed concentration was for A and for B. The viability of post-thawed sperm from A and B individual was 24.0% and 19.0%, respectively. Pre-freezing motility of A and B individual semen was 68.54% and 56.65. Leopard cat A had more normal sperm than that of B (69.5% vs. 54.5%). Acrosome integrity analysis detected live (14.5% vs. 9.0%), damage (39.0% vs. 44.0%) and dead (46.0% vs. 47.0%) in leopard cat A and B, respectively. The present results concluded that leopard cat semen can be collected successfully by electro-ejaculation method and cryopreserved successfullyfor future use in different assisted reproductive technologies. The cryopreservation protocol needs to be modified for increasing post-thawed viability of leopard cat spermatozoa.
        4,000원
        13.
        2008.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Experiments with a URT-0.5 accelerator (0.5 MeV, 50 ns, 1 kW) generating a nanosecond electron beam for irradiation of silver nitrate in various liquid solutions (water and toluene) were performed with the aim of producing silver nanopowders. A radiochemical reaction allows making weakly agglomerated pure Ag powders with particles of 10-15 nm and 30-50 nm in size by irradiation in toluene and water respectively. The injection of the nanosecond electron beam energy to the solution is optimal. As the absorbed dose increases, the output of the radiochemical reaction does not grow, but more agglomerated powders are synthesized.
        4,000원
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