• 천문학회보
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• 제40권1호
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• pp.57.4-57.4
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• 2015

Light bending by gravity was the key prediction of general relativity. Solar eclipse expedition of 1919 provided the observational support for the theory of general relativity. Diverse gravitational lensing, i.e., light bending, phenomena have been speculated and predicted by general relativity and ultimately discovered many years later. Gravitationally lensed quasars, luminous arcs, weak lensing, and microlensing have provided invaluable information about the distribution of matter, especially of dark matter, and the cosmology. Gravitational lensing is one of the most spectacular manifestation of general relativity and will remain as an extremely useful astrophysical tools in the future.

• 대한수학회지
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• 제38권2호
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• pp.321-336
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• 2001

A Feynman functional formulation is given for the Global Positioning System, GPS. Both the sequential and analytic Feynman functionals are presented for the classical, exterior, gravity problems which included rigid body rotations, special relativity and some general relativity corrections. A mathematically rigorous approach is introduced whose solutions exist, are unique and which depend continuously on the intial data. This formulation is convergent and has the finite approximation property. It is emphasized that all of the problems studied are classical (not quantum) evolution systems.

• 천문학회보
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• 제45권1호
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• pp.48.3-48.3
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• 2020

Using redshift-space distortion, I reconstruct the growth history as a smooth function using model independent methods. Assuming general relativity, I obtain the expansion history independently of the dark energy model, and test it to the supernovae data. The results are consistent with general relativity as gravity and the cosmological constant as dark energy, although interestingly negative dark energy densities are not ruled out by the data at z~0.7 to 1.

• 대한수학회보
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• 제24권1호
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• pp.31-37
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• 1987

I want to focus on developments in the areas of general relativity and gauge theory. The topics to be considered are the singularity theorms of Hawking and Penrose, the positivity of mass, instantons on the four-dimensional sphere, and the string picture of quantum gravity. I should mention that I will not have time do discuss either classical mechanics or symplectic structures. This is especially unfortunate, because one of the roots of differential geometry is planted firmly in mechanics, Cf. [GS]. The French geometer Elie Cartan first formulated his invariant approach to geometry in a series of papers on affine connections and general relativity, Cf. [C]. Cartan was trying to recast the Newtonian theory of gravity in the same framework as Einstein's theory. From the historical perspective it is significant that Cartan found relativity a convenient framework for his ideas. As about the same time Hermann Weyl in troduced the idea of gauge theory into geometry for purposes much different than those for which it would ultimately prove successful, Cf. [W]. Weyl wanted to unify gravity with electromagnetism and though that a conformal structure would fulfill thel task but Einstein rebutted this approach.

• 천문학회지
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• 제34권4호
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• pp.215-224
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• 2001

We present the whole basis of numerical method and useful formulae for general relativistic magnetohydrodynamic simulations in Kerr space-time.

• 인문언어
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• 제2권1호
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• pp.7-42
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• 2002

This paper reexamines ideas about linguistic relativity in the light of new interest in the theoretical climate. The original idea is based on the incommensurability of the semantic structures of different languages. On this view, language, thought, culture are deeply interconnected, so that each language might be associated with it a distinctive world view. Throughout this work I utilize the historico-epistemological standpoint to dissect the conceptual structure of this principle. In the introduction I will of for a justification of choice of the theme. Section 1 will address some essential definition of the linguistic principle and insist on the necessity to elaborate a typological spectrum of relativism and universalism. In the second section some important landmarks of linguistic relativity were marked from Plato to Humboldt via Condillac and Herder. 1 will subdivide the relativity hypothesis into 3 theses which are interlated. In the final section the epistemological structure of the linguistic principle will be analysed in some detail by providing my exposition of Sapir-Whorf hypothesis. By way of conclusion I will present the works of Wierzbicka who demonstrated the lexicons of different languages suggest different conceptual universes. By rejecting analytical tools derived from the English language she proposed instead a natural semantic metalanguage based on lexical universals, which is made up of universal semantic primitives. In this paper we attempted to construct a general problematics of linguistic relativity, focolizing on the Sapir-Whorf hypothesis. We devided this very problematic question into its ontological and epistemological dimensions. In particular the ambivalance of Whorf's relativity is discussed in some detail. Also, an archeological survey of this subtle question on the relation between language, thinking and culture was provided. (from Aristotle to Humboldt, via Condillac and Nitzche). In conclusion this investigation underlines the necessity of preparing the cultural linguistics to enlarge the scope of contempory linguistics.

• 천문학회보
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• 제40권1호
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• pp.58.1-58.1
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• 2015

Gravitational-wave has been predicted by Einstein's general relativity in 1916, but its direct detection has failed to date despite of the persistent efforts in the last fifty years in the ground-based gravitational wave detectors. In the centennial year of the birth of general relativity, 'advanced LIGO', one of the most promising Earth-based gravitational wave detectors, plans to start commissioning for the successful discovery of gravitational waves. In addition, a pathfinder satellite of eLISA project, a space-based GW antenna by European Space Agency (ESA), will be launched in the mid of this year. In this talk, we review the current status of gravitational waves detection experiments and discuss its scientific impacts and the possibility of opening the new age of astronomy.

• 천문학회보
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• 제40권1호
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• pp.57.5-58
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• 2015

We describe relations between modern cosmology and general relativity in the historical context. We reveal some ironies imbedded in Einstein's final correction of his gravitational field equation in the context of cosmology in 1917 which has apparently opened a new era of modern physical cosmology. The ugly (according to Einstein) correction term was introduced only to build a static cosmology which turns out to be in flat contradiction with observation. Somehow, however, it is the correction term which has saved the modern cosmology from the genuine creativity of nature continuously revealed by astronomical observations. Whether the present precision cosmology is also a correct one is often ignored by the practitioners but still a pressing open question left for future theoretical and observational pursuits.

• 호남수학학술지
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• 제45권2호
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• pp.316-324
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• 2023

The P-curvature tensor has been studied in the space-time of general relativity and it is found that the contracted part of this tensor vanishes in the Einstein space. It is shown that Rainich conditions for the existence of non-null electro variance can be obtained by P_𝛼𝛽. It is established that the divergence of tensor G_𝛼𝛽 defined with the help of P_𝛼𝛽 and scalar P is zero, so that it can be used to represent Einstein field equations. It is shown that for V₄ satisfying Einstein like field equations, the tensor P_𝛼𝛽 is conserved, if the energy momentum tensor is Codazzi type. The space-time satisfying Einstein's field equations with vanishing of P-curvature tensor have been considered and existence of Killing, conformal Killing vector fields and perfect fluid space-time has been established.

• 대한수학회보
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• 제46권1호
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• pp.61-66
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• 2009

We provide a generalized Myers theorem under integral curvature bound and use this result to obtain a closure theorem in general relativity.