• 천문학회보
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• 제43권1호
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• pp.53.1-53.1
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• 2018

During a major solar eruption, the erupting plasma is possibly out of the equilibrium ionization state because of its rapid heating or cooling. The non-equilibrium ionization process is important in a rapidly evolving system where the thermodynamical time scale is shorter than the ionization or recombination time scales. We investigate the effects of non-equilibrium ionization on EUV and X-ray observations by the Atmospheric Imaging Assembly (AIA) on board Solar Dynamic Observatory and X-ray Telescope (XRT) on board Hinode. For the investigation, first, we find the emissivities for all the lines of ions of elements using CHIANTI 8.07, and then we find the temperature responses multiplying the emissivities by the effective area for each AIA and XRT passband. Second, we obtain the ion fractions using a time-dependent ionization model (Shen et al. 2015), which uses an eigenvalue method, for all the lines of ion, as a function of temperature, and a characteristic time scale, $n_et$, where $n_e$ and t are density and time, respectively. Lastly, the ion fractions are multiplied to the temperature response for each passband, which results in a 2D grid for each combination of temperature and the characteristic time scale. This is the set of passband responses for plasma that is rapidly ionized in a current sheet or a shock. We investigate an observed event which has a relatively large uncertainty in an analysis using a differential emission measure method assuming equilibrium ionization state. We verify whether the observed coronal plasmas are in non-equilibrium or equilibrium ionization state using the passband responses.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• 제26권1호
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• pp.43-58
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• 1998

The Kwinana Shoreline Fumigation Experiment (KSFE) took place at Fremantle, WA, Australia between January 23 and February 8, 1995. The CSIRO DAR LIDAR measured plume sections from near the Kwinana Power Station (KPS) stacks to up to about 5 km downstream. It also measured boundary layer aerosols and the structure of the boundary layer on some occasions. Both stages A and C of KPS were used as tracers at different times. The heart of the LIDAR system is a Neodymium-doped Yttrium-aluminum-garnet (Nd:YAG) laser operating at a fundamental wavelength of 1064 nm, with harmonics of 532 nm and 355 nm. For these experiments the third harmonic was used because the UV wavelength at 355 nm is eye safe beyond about 50 m. The laser fires a pulse of light 6 ns in duration (about 1.8 m long) and with an energy (at the third harmonic) of about 70 mJ. This pulse subsequently scattered and absorbed by both air molecules and particles in the atmosphere. A small fraction of the laser beam is scattered back to the LIDAR, collected by a telescope and detected by a photo-multiplier tube. The intensity of the signal as a function of time is a measure of the particle concentration as a function of distance along the line of the laser shot. The smoke plume was clearly identifiable in the scans both before and after fumigation in the thermal internal boundary layer (TIBL). Both power station plumes were detected. Over the 9 days of operation, 1,568 plumes scans (214 series) were performed. Essentially all of these will provide instantaneous plume heights and widths, and there are many periods of continuous operation over several hours when it should be possible to compile hourly average plume statistics as well. The results of four days LIDAR observations of the dispersion of smoke plume in the TIBL at a coastal site are presented for the case of stages A and C.

• Archives of Plastic Surgery
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• 제47권3호
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• pp.242-249
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• 2020

Background The Exoscope is a novel high-definition digital camera system. There is limited evidence signifying the use of exoscopic devices in microsurgery. This trial objectively assesses the effects of the use of the Exoscope as an alternative to the standard operating microscope (OM) on the performance of experts in a simulated microvascular anastomosis. Methods Modus V Exoscope and OM were used by expert microsurgeons to perform standardized tasks. Hand-motion analyzer measured the total pathlength (TP), total movements (TM), total time (TT), and quality of end-product anastomosis. A clinical margin of TT was performed to prove non-inferiority. An expert performed consecutive microvascular anastomoses to provide the exoscopic learning curve until reached plateau in TT. Results Ten micro sutures and 10 anastomoses were performed. Analysis demonstrated statistically significant differences in performing micro sutures for TP, TM, and TT. There was statistical significance in TM and TT, however, marginal non-significant difference in TP regarding microvascular anastomoses performance. The intimal suture line analysis demonstrated no statistically significant differences. Non-inferiority results based on clinical inferiority margin (Δ) of TT=10 minutes demonstrated an absolute difference of 0.07 minutes between OM and Exoscope cohorts. A 51%, 58%, and 46% improvement or reduction was achieved in TT, TM, TP, respectively, during the exoscopic microvascular anastomosis learning curve. Conclusions This study demonstrated that experts' Exoscope anastomoses appear non-inferior to the OM anastomoses. Exoscopic microvascular anastomosis was more time consuming but end-product (patency) in not clinically inferior. Experts' "warm-up" learning curve is steep but swift and may prove to reach clinical equality.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 1996년도 봄 학술발표회 초록집
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• pp.22-22
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• 1996

;The Kwinana Shoreline Fumigation Experiment(KSFE) took place in Fremantle, WA, Australia between 23 January and 8 February, 1995. All measurement systems performed to expectation. The CSIRO DAR(Division of Atmospheric Research) LIDAR measured plume sections from near the Kwinana Power Station(KPS) stacks to up to about 5 km downstream. It also measured boundary layer aerosols and the structure of the boundary layer on some occasions. Both stages A and C of KPS were used as tracers at different times. Radiosonde and double theodolite sounding systems measured temperature, humidity, air pressure and wind structure at the coast(Woodman Point) and at the inland(ALCOA residue dump) site at intervals of roughly two hours. These were supplemented by mid afternoon soundings(radiosonde and single theodolite) by Department of Environmental Protection(DEP) at Swanbourne. The Flinders aircraft measured wind, turbulence and temperature structure of the atmospheric boundary layer, concentrations of $C0_2,\;0_3,\;S0_2\;and\;NO_x$ in the smoke plumes and surface radiation over both land and sea. CSIRO DCET(Division of Coal and Energy Technology) vehicle successfully interceptde many smoke plumes and using a range of tracers will be able to identify the various sources much of the time. Routine data from the DEP and Kwinana Industrial Council(KIC) air quality monitoring networks were also automatically logged. Murdoch University measured surface heat flux at Hope Valldy monitoring station and also at Wattleup monitoring station for the last five days. The heart of the LIDAR system is a Neodymium-doped Yttrium-aluminumgarnet(Nd:Y AG) laser operating at a fundamental wavelength of 1064 nm, with harmonics fo 532 nm and 355 nm. A small fraction of the laser beam is scattered back to the LIDAR, collected by a telescope and detedted by a photomultiplier tube. The intensity of the signal as a function of time is a measure of the particle concentration as a function of distance along the line of the laser shot. The results of nine days special field observations are summarized in detail.etail.

• 천문학회보
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• 제41권1호
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• pp.75.4-76
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• 2016

DEEP-South (Deep Ecliptic patrol of the Southern sky) is one of the secondary science projects of KMTNet (Korea Microlensing Telescope Network). The objective of this project is twofold, the physical characterization and the discovery of small Solar System bodies, focused on NEOs (Near Earth objects). In order to achieve the goals, we are implementing a software package to detect and report moving objects in the $18k{\times}18k$ mosaic CCD images of KMTNet. In this paper, we present preliminary results of the moving object detection experiments using the prototype MODP (Moving Object Detection Program). We utilize multiple images that are being taken at three KMTNet sites, towards the same target fields (TFs) obtained at different epochs. This prototype package employs existing softwares such as SExtractor (Source-Extracto) and SCAMP (Software for Calibrating Astrometry and Photometry); SExtractor generates catalogs, while SCAMP conducts precision astrometric calibration, then MODP determines if a point source is moving. We evaluated the astrometric accuracy and efficiency of the current version of MODP. The plan for upgrading MODP will also be mentioned.

• 천문학논총
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• 제11권1호
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• pp.177-196
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• 1996

We have investigated the astronomical observational environments at the Choejung-san GEODSS site which is located at the south of Taegu, Korea. As a part of the investigation, seeing and night sky brightness were measured outside nearby the GEODSS site using the Celestron 8-inch portable reflector with $192{\times}165$ pixels Lynxx CCD camera during the period of December 1994 to April 1996. The average seeing values of 4.8 arcsecond in B filter and 5.1 arcsecond in V filter were determined using the IRAF software. These values might be overestimated and would be reduced by at least 1 arc second in both filters if they were measured by more stable telescope system with solid mount and under a dome. We also compare the average seeing value at the GEODSS site with those at three other observatories, the Bohyunsan Optical Astronomy Observatory, the Sobaeksan Optical Astronomy Observatory, and the Seoul National University Observatory, for justification of the above guess. Unfortunately the night sky brightness measurement was not successful mainly due to the short exposure time. The utilizing plan of the GEOSS site is discussed based on the average seeing value, naked-eye sky brightness measurement, analysis of the existing thirty-year weather data and twenty-year urban planning of the metropolitan Taegu city for the year of 2016.

• 천문학회보
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• 제37권2호
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• pp.209.2-209.2
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• 2012

UFFO Burst Alert & Trigger telescope (UBAT) is one of major instruments of UFFO-Pathfinder. The UBAT aims at 10 arcmin resolution localization of Gamma Ray Bursts with X-ray coded mask technique. It has $400mm{\times}400mm$ coded mask aperture, hopper, shielding and detector module with effective area of $191cm^2$. The detector module consists of an assembly of 36 64-ch MAPMTs and $25mm{\times}25mm$ pixellated YSO crystal array, and associated analog and digital electronics of about 2500 channels. We performed a vibration test using a dummy MAPMT with the detector module structure to measure the indused stress applied onto the MAPMT. We designed a sub-structure on the detector module to avoid the resonance that would otherwise deforms the detector module structure. A finite element analysis confirms the reduction of the load acceleration down to 12g. The experimental results are to be reported. Consequently, it proves that the MAPMT arrays of the flight UBAT detector module structure would survive in the space launch environment.

• 한국광학회지
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• 제22권3호
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• pp.151-158
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• 2011

본 논문에서는 반사형 장거리 정밀 변위 감지기용 광학계를 설계하고 실제 구성을 해 봄으로써 작동 성능을 측정한 결과를 소개하고자 한다. 10 m ~ 250 m 거리에 있는 교량 및 건축물 등의 진동 및 변위를 감지하는 장거리 변위 감지기용 광신호 송신 및 수신용 광학계를 설계하고, 관측 거리에 따라 관측 대상체에 다양한 반사광학계를 설치하여 실제 제작된 변위 감지기의 변위 감지 분해능을 측정하였다. 광신호 송신부는 두 개의 850 nm 파장대 LED와 수렴광학계로 구성되고, 수신부에서는 위치 센서(PSD: Position Sensitive Detector)와 망원형 수렴광학계가 사용되었다. 관측 대상체의 거리에 따라 10 m 거리에서는 0.1 mm 변위 분해능과 250 m 거리에서는 3 mm 이하의 변위 분해능이 가능함을 확인하였다.

• 천문학회보
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• 제43권2호
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• pp.39.2-39.2
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• 2018

RR Tel is an interacting binary system in which a hot white dwarf (WD) accretes matter from a Mira variable via gravitational capture of the stellar wind. We present a high-resolution optical spectrum of RR Tel obtained with MIKE at Magellan-Clay telescope, Chile. We find broad emission features at 6825, 7082, 7023, and $7053{\AA}$, which are formed through Raman scattering of far-UV O VI ${\lambda}{\lambda}$ 1032 and $1038{\AA}$, C II ${\lambda}{\lambda}$ 1036 and $1037{\AA}$ with atomic hydrogen. Raman O VI 6825 and 7082 features are characterized by double-peaked profiles indicative of an accretion flow with a characteristic speed ~ 30km/s, whereas the Raman C II features exhibit a single Gaussian profile with FWHM ${\sim}10{\AA}$. Monte Carlo simulations for Raman O VI and C II are performed by assuming that the emission nebula around the WD consists of the inner O VI disk with a representative scale of 1 AU and the outer part with C II sphere. The best fit for Raman profiles is obtained with an asymmetric matter distribution of the O VI disk, the mass loss rate of the cool companion ${\dot{M}}{\sim}2{\times}10^{-6}M_{{\odot}/yr}$ and the wind terminal velocity v~10 km/s. We also find O VI doublet at 3811 and $3834{\AA}$, which are blended with other emission lines. Our profile decomposition shows that the O VI ${\lambda}{\lambda}$ 3811, 3834 doublet have a single Gaussian profile with a width ~ 25 km/s. A comparison of the restored fluxes of C II ${\lambda}{\lambda}$ 1036 and 1037 from Raman C II features with the observed C II ${\lambda}1335$ leads to an estimate of a lower bound of N(CII) > $9.87{\times}10^{13}cm^{-2}$ toward RR Tel, which appears consistent with the presumed distance D ~ 2.6 kpc.

• 천문학회보
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• 제46권1호
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• pp.46.1-46.1
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• 2021

Hydrated asteroids get widespread attention for the evolution of water in the Solar System, especially thanks to the recent successes of the Hayabusa2 and OSIRIS-REx space missions. The target asteroids of these missions are believed to be fragments that have experienced aqueous alteration in their parent bodies [3]. Although hydrated asteroids have been studied well via spectroscopy, focusing on the 0.7 um or the 2.7 um absorption bands [2, 3, 4], polarimetric properties of these asteroids have rarely been investigated. In this study, we conducted a polarimetric observation of 18 C-complex main-belt asteroids with the 1.6-m Pirka telescope at the Nayoro Observatory of Hokkaido University, Japan. We used a polarimetric imaging mode of the Multi-Spectral Imager (MSI) with the standard Rc-band filter (the central wavelength at 0.64 um) [5]. As a result, we found that all of these hydrated asteroids indicate deep negative branches of their polarimetric profiles. Accordingly, the hydrated asteroids have the polarization minima (Pmin), whose values are significantly lower than any other taxonomic types of asteroids (including C-group asteroids). Because Pmin depends on albedo, particle size, and porosity of the surface materials [1], we suspect that hydrated asteroids are distinctive from other asteroids in terms of these physical properties. In this presentation, we introduce our polarimetric observation and findings. We discuss why hydrated asteroids indicate such low Pmin values, comparing Pmin with spectral features at 0.7 um and 2.7 um based on the observation results.