• Journal of Astronomy and Space Sciences
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• v.38 no.1
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• pp.45-53
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• 2021

GLONASS, a satellite navigation system developed in Russia since 1976, is defunct and orbits in an unstable attitude. The satellites in these problems are not managed and there is no precise information, which can increase the risk of collisions with other space objects. In this study, detailed attitude dynamic have to be analyzed through photometry data, which requires spin period and spin axis. The light curve data is obtained by observing through the photometer at the Graz station and the power spectrum is calculated to obtain the cycle of the satellite. The geometric relationship between observer and sun is analyzed for GLONASS-50 satellite. The box-wing model is applied to obtain the phase reflection of the satellite and obtain the Irradiation of the satellite through this information. In Light Curve and Irradiation, the spin axis is calculated for each peak points with the distance square minimum technique. The spin axis of the GLONASS-50 satellite is RA = 116°, Dec = 92°.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.46.1-46.1
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• 2020

DEEP-South (DEep Ecliptic Patrol of the Southern Sky) team will start the 2nd phase of KMTNet observation in Oct 2020. The DEEP-South observation mainly consists of three survey modes: (1) Activity survey (AS) that aims at finding active phenomena of small Solar System bodies. (2) Light curve survey (LS) targets to discover and characterize light variations of asteroids. And (3) Deep drilling survey (DS) focuses on the objects beyond the orbit of Jupiter (Centaurus and trans-Neptunian objects) as well as near Earth asteroids. For asteroid family (AF) studies and target of opportunity (TO) observations for urgent photometric follow-up, targeted mode will also be used. DEEP-South team is awarded 7.0% of the telescope time at each site every year from Oct 2020 to Sep 2023 in the 2nd phase of KMTNet operation which corresponds to about 75 full nights a year for the network. In this presentation, we will introduce our survey strategy and observation plan.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.43.1-43.1
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• 2013

We present here the preliminary results of the fast variability of AGN radio light curves. The shortest time scale of minute in AGN light curves is needed to probe the AGN activity for a few reasons; First, to check if there is any kind of shortest time scale activity. Secondly, to find out what high frequency end of AGN spectra look like. For the last, to see the time delay at several wavelength bands and the change of the spectral index with time. The observation was conducted with three KVN(Korea VLBI Network) antennas with single dish cross scan mode. In order not to lose the target at any given time, whenever one station needs to observe the calibrator, the other station is on the target. Though the detailed data reduction is still going on, there might exist varying feature in the radio light curve. The more fine calibration will be done in near future and another good data set is ready for the reduction.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.37.2-37.2
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• 2021

One of the main limitations to the ground- based gravitational-wave (GW) detector sensitivity is quantum noise, which is induced by vacuum fluctuations entering the detector output port. The replacement of this ordinary vacuum field with a squeezed vacuum field has proven to be effective approach to mitigate the quantum noise in the interferometer detector and it is currently used in advanced detectors. However, the current frequency-independent squeezed vacuum cannot reduce quantum radiation pressure noise at low frequencies. A possible solution to reduce quantum noise in the broadband spectrum is the injection of frequency-dependent squeezed (FDS) vacuum. We will report the current status of squeezing experiment at KASI and introduce to the EPR (Einstein-Podolsky-Rosen) entangled state of light, which can realize FDS light without the need for an additional, external cavity.

• Bulletin of the Korean Space Science Society
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• 1996.05a
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• pp.22-22
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• 1996

No Abstract, See Full Text

• Journal of Astronomy and Space Sciences
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• v.12 no.1
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• pp.44-53
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• 1995

BVRI observatins of AW UMa were made from March to April during 13 nights in 1994 using the 35cm Schmidt-Cassegrain telescope of Department of Astronomy and Space Science, Chungbuk National University. A total of 1092 observations (273 in B, 273 in V, 273 in R, 273 in I) were obtained. We constructed the light curves of BVRI with these observations. The one time of primary minimum light of JD Hel 2449456.1502 and the two times of secondary minimum light of JD Hel 2449456.1502 and JD Hel 2449447.1567 were determined from our observations. Orbital period change of -0.d00000394 was determined from O-C diagram which was constructed with collected times of minimum lights. Mass transfer rate of $-6.4\times10^{-7}M_\odot/year$ was derived using the period changing ratio. It is suggested that the inhomogeneous distribution of transferred matter around the secondary component would produce the irregular light variation of the AW UMa system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1045-1052
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• 2011

Recently, because of complex cultural space, underground space are becoming larger. Therefore, the demand for location-based services is growing. VLC (Visible Light Communication) is based on the LED lighting infrastructure so that suitable LBS (Location-based service) is possible for the targeted places in indoor space. To experiment with indoor LBS by VLC, we measure the identification distance according to variable angles between LED and photo diode. We send the different ASCII code for each LED light, then we found the maximum identification distance is 1.75m from LED lights. From the results of this experiment, we show that indoor navigation is possible.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2007.05a
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• pp.91-94
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• 2007

The change of modern society arouse the issue of the family structure and the demand of upbringing. According to the issue, the need of the upbringing is the big interest in society. This study is on the necessity of the eco-environmental space in public child care center. The study progressed with the result of the prior study, the demand of the parents of students in eco-environmental space in child care center. The results of the study are first, the natural light source can import in sky light, side light and atrium in child care center. Second, the indoor garden and interior plants would give the natural feelings. Third, the ponds and waterways in indoor and outdoor would give the empirical experiences. And the last, the stone and clay would give the tender feelings in interior and the sand play in outdoor would give the activities. This study would be the foundation on the upcoming study of the needs of the eco-environmental spaces in child facilities.

• Korean Institute of Interior Design Journal
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• v.23 no.3
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• pp.75-82
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• 2014

The aim of this study is to review phenomenological characteristics in Alvaro Siza's works through his design intention, methods and results. As a Portuguese architect, his personal and local background as well as pursuing the essence of architecture made phenomenological characteristics of his works. The emphasis of the placeness of site and the existence of architecture has close relationship with Heidegger's concept of dwelling and the role of architecture. Although Siza has maintained white plat plane of interior space which is one of features of modern architecture, he provides dramatic and dynamic experiences of space using curved and acute angle of plane in his latter part of works. Another his phenomenological nature of buildings is a striking display of space and light which is remarkable especially in his museum designs. He made this character in adopting various shapes of double ceilings, openings and their combination with natural light which he always emphasizes. As a result, Alvaro Siza's phenomenological characteristics comes not from clear architectural or philosophical theory but from continuous practice based on pursuing the essence of architecture.

• Current Optics and Photonics
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• v.6 no.4
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• pp.420-429
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• 2022

In this paper, the details and design process of an optical system for space target detection cameras are introduced. The whole system is divided into three structures. The first structure is a short-focus visible light system for rough detection in a large field of view. The field of view is 2°, the effective focal length is 1,125 mm, and the F-number is 3.83. The second structure is a telephoto visible light system for precise detection in a small field of view. The field of view is 1°, the effective focal length is 2,300 mm, and the F-number is 7.67. The third structure is an infrared light detection system. The field of view is 2°, the effective focal length is 390 mm, and the F-number is 1.3. The visible long-focus narrow field of view and visible short-focus wide field of view are switched through a turning mirror. Design results show that the modulation transfer functions of the three structures of the system are close to the diffraction limit. It can further be seen that the short-focus wide-field-of-view distortion is controlled within 0.1%, the long-focus narrow-field-of-view distortion within 0.5%, and the infrared subsystem distortion within 0.2%. The imaging effect is good and the purpose of the design is achieved.