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        검색결과 24

        1.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The telescope to be onboard SPICA (Space Infrared Telescope for Cosmology and Astrophysics) has an aperture diameter of 2.5 m and its imaging performance is to be diffraction-limited at a wavelength of 20 μm at the operating temperature of <8 K. Because manufacturing precise autocollimating at mir- rors (ACFs) with sizes comparable to the SPICA telescope is not technically feasible, we plan to use sub-aperture stitching interferometry through ACFs for optical testing of the telescope. We have verified the applicability of the sub-aperture stitching technique to the SPICA telescope by performing stitching experiments in a vacuum at a room temperature, using the 800-mm telescope and a 300-mm ACF. We have also developed a new method to reduce uncertainties possibly caused by cryogenic and gravitational deformations of ACFs.
        3,000원
        2.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        For future space IR missions, such as SPICA, it is crucial to establish an experimental method for eval- uating the performance of mid-IR detectors. In particular, the wavelength dependence of the sensitivity is important but difficult to be measured properly. We are now preparing a testing system for mid-IR Si:As/Si:Sb detectors on SPICA. We have designed a cryogenic optical system in which IR signal light from a pinhole is collimated, passed through an optical filter, and focused onto a detector. With this system, we can measure the photoresponse of the detector for various IR light using optical lters with different wavelength properties. We have fabricated aluminum mirrors which are adopted to minimize thermal distortion effects and evaluated the surface figure errors. The total wavefront error of the optical system is 1.3 μm RMS, which is small enough for the target wavelengths (20-37 μm) of SPICA. The point spread function measured at a room temperature is consistent with that predicted by the simulation. We report the optical performance of the system at cryogenic temperatures.
        3,000원
        3.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper reviews the legacy of the SPCIA Coronagraph Instrument (SCI) of which the primary scienti c objective is the characterization of Jovian exoplanets by coronagraphic spectroscopy in the infrared. Studies on binary shaped pupil mask coronagraphs are described. Cryogenic active optics is discussed as another key technology. Then approaches to observing habitable zones in exoplanetary systems with a passively-cooled space infrared telescope are discussed. The SCI was dropped in a drastic change of the SPICA mission. However, its legacy is useful for space-borne infrared telescopes dedicated for use in exoplanetary science in the future, especially for studies of biomarkers.
        3,000원
        4.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper reviews the requirements for far-infrared astronomy in the period following the SPICA satellite in the late 2020's. We take a very long view of the state of FIR astronomy and what facilities will be required in a twenty year timeframe. We show that spatial resolution to match that of observatories operating in the optical and mid-infrared and the radio will be a necessity. Moreover this high spatial resolution must be combined with high spectral and photometric sensitivity to provide the data required to further our understanding of planetary formation mechanisms, the history of star formation through cosmic time and the feedback between active galactic nuclei and their host galaxies in controlling star formation. We review three possible conceptual mission scenarios and comment on the possibility of realising them in the coming deades.
        4,000원
        5.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We present project updates of the next-generation infrared space mission SPICA (Space Infrared Tele- scope for Cosmology and Astrophysics) as of November 2015. SPICA is optimized for mid- and far-infrared astronomy with unprecedented sensitivity, which will be achieved with a cryogenically cooled (below 8 K), large (2.5 m) telescope. SPICA is expected to address a number of key questions in various fields of astrophysics, ranging from studies of the star-formation history in the universe to the formation and evolution of planetary systems. The international collaboration framework of SPICA has been revisited. SPICA under the new framework passed the Mission Definition Review by JAXA in 2015. A proposal under the new framework to ESA is being prepared. The target launch year in the new framework is 2027/28.
        4,000원
        6.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We propose a cosmological survey to probe star formation and nuclear activity in galaxies at redshifts of z=2-4 by polycyclic aromatic hydrocarbon (PAH) features using the SPICA mid-infrared instrument (SMI) with a spectral resolution of R=20. We will cover a wavelength range of 20-36 μm that corresponds to z=2-4 for the PAH features (11.3, 7.7, and 6.2 μm). The sensitivity will be 1 X 10-19 W/m2 (5 σ) in case of a reference survey that covers 4 arcmin2 field in a one-hour observation. It corresponds to LIR=2 X 1011 L⊙ at z=3 and will give us more than 10000 galaxies in a 450 hour survey.
        3,000원
        7.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Submillimetre and millimetre-wave surveys with Herschel and the South Pole Telescope have revolu- tionised the discovery of strong gravitational lenses. Their follow-ups have been greatly facilitated by the multi-wavelength supplementary data in the survey fields. The forthcoming Euclid optical/near-infrared space telescope will also detect strong gravitational lenses in large numbers, and orbital constraints are likely to require placing its deep survey at the North Ecliptic Pole (the natural deep field for a wide class of ground-based and space-based observatories including AKARI, JWST and SPICA). In this paper I review the current status of the multi-wavelength survey coverage in the NEP, and discuss the prospects for the detection of strong gravitational lenses in forthcoming or proposed facilities such as Euclid, FIRSPEX and SPICA.
        4,000원
        8.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We present the current status (as of August 2014) of SPICA (Space Infrared Telescope for Cosmology and Astrophysics), which is a mission optimized for mid- and far-infrared astronomy with a cryogenically cooled 3m-class telescope. SPICA is expected to achieve high spatial resolution and unprecedented sensitivity in the mid- and far-infrared, which will enable us to address a number of key problems in present-day astronomy, ranging from the star-formation history of the universe to the formation of planets. We have carried out the "Risk Mitigation Phase" activity, in which key technologies essential to the realization of the mission have been extensively developed. Consequently, technical risks for the success of the mission have been significantly mitigated. Along with these technical activities, the international collaboration framework of SPICA has been revisited, which resulted in la arger contribution from ESA than that in the original plan. To enable the ESA participation under the new framework, a SPICA proposal to ESA is under consideration as a medium-class mission under the framework of the ESA Cosmic Vision. The target launch year of SPICA under the new framework is the mid-2020s.
        3,000원
        9.
        2014.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        체내에 과도하게 생성되는 활성산소는 산화적 스트레스를 유발할 수 있으며 세포 구성성분들을 손상시키고 각종질환의 원인이 될 수 있다. 또한 최근의 연구 결과에 따르면 비만한 사람은 정상체중을 가진 일반인들에 비해 높은산화적 스트레스 상태임이 알려졌다(Furukawa et al.,2004). 본 연구에서는 전통 한약재로 잘 알려진 하고초ethanol 추출물의 항비만 및 스트레스 억제활성을 3T3-L1및 HepG2 세포에서 평가하였다. 본 연구의 결과를 요약하자면 다음과 같다. 첫째, 50 및 100μg/mL의 하고초 추출물은 각각 대조군 대비 78.4%, 및 72.3%의 3T3-L1 세포의지방세포 분화를 억제하였다. 둘째, 100μg/mL의 하고초 추출물은 HepG2 세포에서 ethanol에 의해 유도된 세포사멸을유의적으로 보호하였다(대조군 대비 79.3%). 셋째, 10, 100및 200μg/mL의 하고초 추출물은 60μM의 AAPH 및10μM의 Cu2+로 유도된 산화적 스트레스를 농도 의존적이며 유의적으로 억제하였다. 이상의 연구결과는 하고초 추출물이 항비만 및 산화적 스트레스 억제를 통한 기능성 소재로서의 가능성을 보여주는 결과라 생각된다.
        4,000원
        13.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The SPICA (SPace Infrared Telescope for Cosmology & Astrophysics) project is a next-generation infrared space telescope optimized for mid- and far-infrared observation with a cryogenically cooled 3m-class telescope. It will achieve the high resolution as well as the unprecedented sensitivity from mid to far-infrared range. The FPC (Focal Plane Camera) proposed by KASI as an international collaboration is a near-infrared instrument. The FPC-S and FPC-G are responsible for the scientific observation in the near-infrared and the fine guiding, respectively. The FPC-G will significantly reduce pointing error down to below 0.075 arcsec through the observation of guiding stars in the focal plane. We analyzed the pointing requirement from the focal plane instruments as well as the error factors affecting the pointing stability. We also obtained the expected performance in operation modes. We concluded that the FPC-G can achieve the pointing stability below 0.075 arcsec which is the requirement from the focal plane instruments.
        4,000원
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