• Publications of The Korean Astronomical Society
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• v.39 no.2
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• pp.53-67
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• 2024

Islamic Jamal al-Din zij and Chinese Shoushi-li(授時曆) are astronomical hand books compiled by Jamal al-Din(札馬魯丁) and Guo Shujing(郭守敬) of the Islamic and Chinese Astronomical Bureau in Yuan(元) China, respectively. Jamal al-Din zij is an Islamic zij based on the Almagest of Ptolemaios, while Shoushii-li is a calendrical treatise by the traditional Chinese calendar system. In case of the parallax correction method, however, both of them have a common origin from Indian astronomy in 6-7 Century. This paper examines and discusses the parallax theory and its origin adopted in Jamal al-Din zij and Shoushi-li as following: 1) Definitions of the parallax theory and parallax correction methods. 2) Similarities and origins of the parallax correction methods adopted in the Jamal al-Din zij and Shoushi-li. 3) Comparison of the parallax correction tables included in the Sanjufini zij of Tibet, the Huihui-lifa(回回曆法) of Ming(明) China and the Chiljeongsan-Oepyeon(七政算外篇) of Joseon(朝鮮) Korea. 4) Routes of the parallax theory transmitted from ancient Greece and India to Joseon via Islam world and China, respectively. 5) Astronomical exchanges and mutual influence between the East and the West.

• Journal of Astronomy and Space Sciences
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• v.24 no.1
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• pp.31-38
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• 2007

We have investigated the evolutionary status of 85 Peg within the framework of standard evolutionary theory. 85 Peg has been known to be a visual and spectroscopic binary system in the solar neighborhood. In spite of the accurate information of the total mass (${\sim}1.5M_{\odot}$) and the distance (${\sim}12pc$) from the HIPPARCOS parallax, it has been undetermined an individual mass, therefore the evolved status of the system. Moreover, the coupled uncertainties of chemical composition and age, make matters worse in predicting an evolutionary status of the system. Nevertheless, we computed the various possible models for 85 Peg, and then calibrated stellar parameters by adjusting to the recent observational data. Our modelling computation has included recently updated input physics and stellar theory such as opacity, equation of state, and chemical diffusion. Through a statistical assessment, we have derived a confident parameter set as the best solution which minimized $X^{2}$ within the observational error domain. Most of all, we found that 85 Peg is not a binary system but a triple system with an unseen companion 85 Peg $B_{b}\;{\sim}0.16M_{\odot}$. The aim of the present paper is (1) to provide a complete modelling of the stellar system based on the evolutionary theory, and (2) to constrain the physical dimensions such as mass, metallicity and age.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.35.1-35.1
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• 2010

Using the spectroscopic analysis and the theoretical modeling, physical properties of the nearby astrometric binary $\mu$ Cas have been determined. In spite of the well-defined parallax and astrometric orbit, there has been a chronic mass ratio problem between components. Recently, the radius of the primary component has been detected from the optical interferometric observation of the CHARA array. Using the high resolution spectroscopic analysis, we found that $\mu$ Cas have $\alpha$-enhanced chemical composition with respect to the scaled solar abundance by a factor of two. Combining our abundance analysis with recently determined physical properties, the consistent models for $\mu$ Cas have been constructed within the frame work of standard stellar theory. Through a statistical minimization between theoretical model grids, a reliable set of physical dimensions has been defined. Furthermore, the mode oscillation frequency of the best model has been calculated.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.4 no.2
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• pp.10-26
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• 1986

In a stereoscopic measurements on the aerial photogrammetric works, it is in general understood that the larger and the larger is a vertical scale exaggeration, the better and the better is height measuring precision. Despite the success with which a stereoscopic measurement has been applied to contour mapping as well as spot height measurement, no generally accepted theory for visual excess has yet been developed. This experiments aim at arrangement of a correlation between visual excess and height measuring precision. The stereoscopic measurements with parallax bar in the mirror stereoscope are carried out on the test model of which consists normal angle, wide angle and super wide angle respectively. With the result of this experiments, it is conclued that height measuring precision is proportional to the magnitude of visual excess.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.10
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• pp.777-788
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• 2006

This paper describes a displacement mapping technique which represents protruded shapes on the surface of an object. Previous approaches for image-based displacement mapping can represent only shapes depressed from the polygon surface. The proposed technique can represent shapes protruded from the underlying surface in real-time. Two auxiliary surfaces which are perpendicular to the underlying surface are added along the boundary of the polygon surface, in order to represent the pixels which overflow over the boundary of the polygon surface. The proposed approach can represent accurate silhouette of protruded shape. It can represent not only smooth displacement of protruded shape, but also abrupt displacement such as perpendicular protrusion by means of adding the supplementary texture information to the steep surface of protruded shape. By per-pixel instructions on the programmable GPU this approach can be executed in real-time. It provides an effective solution for the representation of protruded shape such as high-rise buildings on the ground.