• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.35.1-35.1
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• 2021

RR Lyrae stars are sensitive probe for the precision stellar astrophysics and also for the cosmic distance scale thanks to their well-defined near-infrared Period-Luminosity relations (PLRs). These horizontal branch variables can be used for primary calibration of the first-rung of population II distance ladder providing an evaluation of the ongoing tension between Cepheid-Supernovae based Hubble constant and the Planck results. Therefore, absolute calibration of RR Lyrae PLRs is now crucial to complement or test the tip of the red giant branch based distances, and in turn, population II star based Hubble constant measurements. While the pulsation models of RR Lyrae can reproduce most observables, they predict a significant metallicity effect on their JHKs-band PLRs that is inconsistent with so-far limited observational studies. We remedy this inconsistency of metallicity dependence in RR Lyrae PLRs by combining their near-infrared observations in the globular clusters of different mean-metallicities with the new parallaxes from the Gaia early data release 3 (EDR3). Our empirical results on Period-Luminosity-Metallicity (PLZ)relations are consistent with theoretical predictions but the precision of absolute calibrations is still affected by the parallax uncertainties and the systematic zero-point offset present in the Gaia EDR3.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.10
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• pp.949-955
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• 2007

This paper proposes an efficient localization algorithm in the RFID sensor space for the precise localization of a mobile robot. The RFID sensor space consists of embedded sensors and a mobile robot. The embedded sensors, that is tags are holding the absolute position data and provide them to the robot which carries a reader and requests the absolute position fur localization. The reader, it is called as antenna usually, gets several tag data at the same time within its readable range. It takes time to read all the tags and to process the data to estimate the position, which is a major factor to deteriorate the localization accuracy. In this paper, an efficient algorithm to estimate the position and orientation of the mobile robot as quickly as possible has been proposed. Along with the algorithm, a new allocation of the tags in the RFID sensor space is also proposed to improve the localization accuracy. The proposed algorithms are demonstrated and verified through the real experiments.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.23.2-23.2
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• 2008

We presented the accurate absolute dimensions and distances of fifteen main sequence eclipsing binaries. The photometric and spectroscopic solutions of the binary systems were determined by analyzing light curves and radial velocity curves collected from the literature using the Wilson-Devinney computer code. The fifteen double-line spectroscopic binaries consist of nine detached systems; QX Car, AH Cep, CW Cep, ZZ Cep, XY Cet, RX Her, V451 Oph, VV Pyx and V760 Sco, six semi-detached systems; LY Aur, IU Aur, AO Cas, DM Per, V Pup and HU Tau. The temperatures of the binary systems were determined from their colors using the color-temperature calibrations. Then the temperature of each component star were determined using the temperature ratio which was adjusted from the light curves. We estimated the possible Z values and ages for the detached systems by adopting the Y2 (Yonsei-Yale) stellar evolutionary tracks. The derived distances are in good agreement of the Hipparcos distances whose error of parallax is within 10 %. Finally these well-investigated systems will be used as the standard eclipsing binaries.

• Journal of Astronomy and Space Sciences
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• v.15 no.1
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• pp.83-90
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• 1998

With a total 2780 eclipsing binary systems in the Catalogue of Approximate Photometric and Absolute Elements of Eclipsing Variable Stars by Svechnikov & Kuznetsova(1990), the empirical relations between the systemic mass and orbital argular momentum have been examined. It is found that, during the its evolution, the total orbital argular momentum of the eclipsing binary sustem is not conserved. It decreases gradually, though not at a constant rate, until the system becomes into contact from initially detached via semi-detached system.

• Journal of Astronomy and Space Sciences
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• v.23 no.2
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• pp.91-96
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• 2006

We use near-infrared observations of eight selected Galactic globular clusters to estimate their distances by comparing the observed and theoretically predicted K magnitudes of the red giant branch bumps and tips. The K magnitude levels of the RGB bump and tip have been measured from the luminosity function of the selected RGB stars in the clusters. Theoretical absolute $M_k$ magnitudes of the RGB bump and tip are taken from the Yonsei-Yale isochrones. Comparing the observed apparent K magnitude with the derived absolute $M_k$ magnitude, we calculate the distance moduli of the clusters. We discuss the dependency of the derived distance modulus on the cluster age and the uncertainty of the distance measurement from the near-infrared photometry of the RGB bump and tip.

• Journal of Astronomy and Space Sciences
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• v.23 no.2
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• pp.97-104
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• 2006

From the BV images of the metal-poor globular cluster NGC 1904 obtained with the 2K CCD camera equipped on the BOAO 1.8m telescope, we construct (B - V, V) color-magnitude diagram of the cluster. The apparent V magnitudes of the RGB bump and tip have been measured from the luminosity function of the iteratively selected RGB stars in NGC 1904. Theoretical absolute $M_v$ magnitudes of the RGB bump and tip are estimated using the Yonsei-Yale isochrones. The distance modulus of NGC 1904 has been derived by comparing the observed apparent V magnitude with the estimated absolute $M_v$ magnitude of the RGB bump and tip.

• Journal of The Korean Astronomical Society
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• v.39 no.4
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• pp.151-155
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• 2006

Long slit spectrometers are widely used in optical and infrared bands in astronomy. Absolute flux calibration for extended sources, however, is not straightforward, because a portion of the radiation energy from a flux calibration star is blocked by the narrow slit width. Assuming that the point spread function(PSF) of the star is circularly symmetric, we develop a robust method to extrapolate the detected stellar flux to the unobscured flux using the measured PSF along the slit-length direction. We apply this method to our long slit data and prove that the uncertainty of the absolute flux calibration is less than a few percents.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2005.10a
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• pp.161-164
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• 2005

The concept of Space-time is performed while the movement of human Is imaged on coming 20th century up. Specifically it is considered that the movement of human is caused by the relativistic otherness rather than an absolute subject in space of deconstructive tendency. The purpose of this study is that I try to analyze an expression of relative space-time concept in desconstructive tendency and I have to get a concept how this kind of expression effect the contemporary commercial space. Through this study, I can get to know that the expression of relative space-time concept expresses the dynamic construction by the indeterminacy and the visual effect by the dematerialization in the contemporary commercial interior-space. According to the result of study, the concept of space get to be more meaningful, relative space-time concept and it can be attributed to the concept of human's new creative space over human's life in general.

• Journal of the Korean Statistical Society
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• v.1 no.1
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• pp.18-24
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• 1973

Study on convexity has been improved in many statistical fields, such as linear programming, stochastic inverntory problems and decision theory. In proof of main theorem in Section 3, M. Loeve already proved this theorem with the $r$-th absolute moments on page 160 in [1]. Main consideration is given to prove this theorem using convex theorems with the generalized $t$-th mean when some convex properties hold on a real linear vector space $R_N$, which satisfies all properties of finite dimensional Hilbert space. Throughout this paper $\b{x}_j, \b{y}_j$ where $j = 1,2,......,k,.....,N$, denotes the vectors on $R_N$, and $C_N$ also denotes a subspace of $R_N$.

• Bulletin of the Korean Mathematical Society
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• v.53 no.2
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• pp.561-568
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• 2016

In this paper, the effect of absolute values on the behavior of functions f in the spaces $\mathcal{Q}_K$ is investigated. It is clear that $g{\in}\mathcal{Q}_K({\partial}{\mathbb{D}}){\Rightarrow}{\mid}g{\mid}{\in}\mathcal{Q}_K({\partial}{\mathbb{D}})$, but the converse is not always true. For f in the Hardy space $H^2$, we give a condition involving the modulus of the function only, such that the condition together with ${\mid}f{\mid}{\in}\mathcal{Q}_K({\partial}{\mathbb{D}})$ is equivalent to $f{\in}\mathcal{Q}_K$. As an application, a new criterion for inner-outer factorisation of $\mathcal{Q}_K$ spaces is given. These results are also new for $Q_p$ spaces.