• Journal of Information Technology and Architecture
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• v.10 no.1
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• pp.79-91
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• 2013

This paper proposes a systematic methodology that could be used to decide which one shows the best performance among space filling curves (SFCs) in applying lower-dimensional transformations to histogram sequences. A histogram sequence represents a time-series converted from an image by the given SFC. Due to the high-dimensionality nature, histogram sequences are very difficult to be stored and searched in their original form. To solve this problem, we generally use lower-dimensional transformations, which produce lower bounds among high dimensional sequences, but the tightness of those lower-bounds is highly affected by the types of SFC. In this paper, we attack a challenging problem of evaluating which SFC shows the better performance when we apply the lower-dimensional transformation to histogram sequences. For this, we first present a concept of spatial locality, which comes from an intuition of "if the entries are adjacent in a histogram sequence, their corresponding cells should also be adjacent in its original image." We also propose spatial locality preservation metric (slpm in short) that quantitatively evaluates spatial locality and present its formal computation method. We then evaluate five SFCs from the perspective of slpm and verify that this evaluation result concurs with the performance evaluation of lower-dimensional transformations in real image matching. Finally, we perform k-NN (k-nearest neighbors) search based on lower-dimensional transformations and validate accuracy of the proposed slpm by providing that the Hilbert-order with the highest slpm also shows the best performance in k-NN search.

• Journal of Astronomy and Space Sciences
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• v.3 no.1
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• pp.41-51
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• 1986

Two-photometric light curves(Oh and Chen 1984) of the eclipsing binary TX UMa have been analyzed by the method of differential corrections of the model of Wilson and Devinney (1971). The system found to be simi-detached with the cooler and less massive component filling its Roche lobe. The absolute dimensions have been derived from the results of the photometric solutions with the spectroscopic elements of Hiltner(1945). It is assumed that the B8V primary component is on the zero main sequence stage of the core hydrogen burning and the secondary is at the core contraction stage after the shell hydrogen burning stage according to the Iben's (1967) evolutional tracks for $3.0m_\odot$ and $1.0m_\odot$ .

• Journal of Astronomy and Space Sciences
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• v.26 no.2
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• pp.141-156
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• 2009

Through the photometric observations of the near-contact binary, XZ CMi, new BV light curves were secured and seven times of minimum light were determined. An intensive period study with all published timings, including ours, confirms that the period of XZ CMi has varied in a cyclic period variation superposed on a secular period decrease over last 70 years. Assuming the cyclic change of period to occur by a light-time effect due to a third-body, the light-time orbit with a semi-amplitude of 0.0056d, a period of 29y and an eccentricity of 0.71 was calculated. The observed secular period decrease of $-5.26{\times}10^{-11}d/P$ was interpreted as a result of simultaneous occurrence of both a period decrease of $-8.20{\times}10^{-11}d/P$ by angular momentum loss (AML) due to a magnetic braking stellar wind and a period increase of $2.94{\times}10^{-11}d/P$ by a mass transfer from the less massive secondary to the primary components in the system. In this line the decreasing rate of period due to AML is about 3 times larger than the increasing one by a mass transfer in their absolute values. The latter implies a mass transfer of $\dot{M}_s=3.21{\times}10^{-8}M_{\odot}y^{-1}$ from the less massive secondary to the primary. The BV light curves with the latest Wilson-Devinney binary code were analyzed for two separate models of 8200K and 7000K as the photospheric temperature of the primary component. Both models confirm that XZ CMi is truly a near-contact binary with a less massive secondary completely filling Roche lobe and a primary inside the inner Roche lobe and there is a third-light corresponding to about 15-17% of the total system light. However, the third-light source can not be the same as the third-body suggested from the period study. At the present, however, we can not determine which one between two models is better fitted to the observations because of a negligible difference of $\sum(O-C)^2$ between them. The diversity of mass ratios, with which previous investigators were in disagreement, still remains to be one of unsolved problems in XZ CMi system. Spectroscopic observations for a radial velocity curve and high-resolution spectra as well as a high-precision photometry are needed to resolve some of remaining problems.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.6
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• pp.124-136
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• 2019

Autonomous driving at intersections requires assistance by exchanging traffic information between traffic objects due to the intersection of various vehicles and complicated driving environment. For this reason, traffic information exchange between adjacent intersections is required, but the node ID representing the intersection in the Korean standard node link system have limitations in updating intersections and identifying location information of intersections through IDs due to the configuration system including serial numbers. In this paper, we designed a coordinate-based intersection ID configuration system created by processing and merging two-dimensional coordinates of intersections to include location information in the intersection ID. In order to verify the applicability of the proposed intersection ID, we applied a new intersection ID to domestic intersections and confirmed that there are no duplicate values. Coordinate-based intersection ID reduces data size by 60% compared to existing node ID, and enables spatial queries such as searching for nearby intersections and extracting intersections in specific areas in the form of boxes without GIS tools. Therefore, coordinate-based intersection ID is expected to be more scalable and utilized than existing node ID.