• 천문학회보
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• 제44권1호
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• pp.56.1-56.1
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• 2019

The concordance LCDM model has been very successful at reproducing a wide range of observations. However, the nature of its main components, such as dark energy, dark matter, and inflation, are still unkown. Therefore, it is of prime importance to question the underlying hypotheses of the model and tests there prediction. While most constraints have been obtained assuming a LCDM universe, model-independent approaches, which do not make assumptions regarding the model, are a powerful approach. To falsify the LCDM model, I applied model-indepedent methods to the latests available data to test different aspects of the concordance model, such as the FLRW metric, the curvature, dark energy as the cosmological constant, and gravity as general relativity. The Universe is consistent with flat-LCDM with GR. However, at z>1, tensions start to appear, and more data are required.

• 디지털산업정보학회논문지
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• 제13권1호
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• pp.173-183
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• 2017

The purpose of this study is to find out the difference of sense of self-efficacy and stress encountering strategy of university students under the stress situation depending on the smart-phone user group (addiction group, general user group). For this purpose, the study issues are established as follows. First, it has analyzed what is the correlation of smart-phone addiction, sense of self-efficacy, and stress encountering strategy. Second, it has studied if there is any difference of sense of self-efficacy and stress encountering strategy for the smart-phone user group. In order to verify such study issues, For 1,670 university students in the Chungcheong area, smart-phone addiction scale, sense of self-efficacy scale, and stress encountering method scale were administered. Looking into the study result, first, as a result of the relativity analysis, it displayed the correlation of preference of test difficulty, self-control efficacy and important negative from the smart-phone addiction and sense of self-efficacy. In addition, all sub-variables of smart-phone addiction and avoidance orientation from the stress encountering strategy displayed the important positive correlation, and from the smart-phone addiction, the virtual world orientation and pursuit of social-support displayed the important negative correlations, and all sub-variables (interference with ordinary living, virtual world striving direction, withdrawal, resistance) of smart-phone addiction and problem solving-orientation displayed the negative correlation. Second, as a result of verification for the difference of the smart-phone addiction group and general use group following the sense of self-efficacy, the general use group is shown to have higher self-control efficacy sense than the addiction group. And third, as a result of verifying the difference of stress encountering following the smart-phone addiction group and general use group, the addiction group is shown to be lower than the general use group in terms of social support pursuit and problem solution orientation with the avoidance orientation shown to be higher. This type of result is expected to provide the base data when developing the smart-phone addiction preventive education program by finding out in details for the characteristics of smart-phone addiction group for university students.

• 천문학회보
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• 제40권1호
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• pp.43.3-44
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• 2015

We analyze the clustering of large scale structure in the Universe in a model independent method, accounting for anisotropic effects along and transverse to the line of sight. A large sample of 690,000 galaxies from The Baryon Oscillation Spectroscopy Survey Data Release 11 are used to determine the Hubble expansion H, angular distance D_A, and growth rate GT at an effective redshift of z=0.57. After careful bias and convergence studies of the effects from small scale clustering, we find that cutting transverse separations below 40 Mpc/h delivers robust results while smaller scale data leads to a bias due to unmodelled nonlinear and velocity effects. The converged results are in agreement with concordance LCDM cosmology, general relativity, and minimal neutrino mass, all within the $68{\backslash}%$ confidence level. We also present results separately for the northern and southern hemisphere sky, finding a slight tension in the growth rate -- potentially a signature of anisotropic stress, or just covariance with small scale velocities -- but within $68{\backslash}%$ CL.

• Macromolecular Research
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• 제8권3호
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• pp.131-136
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• 2000

The synthesis of poly(2-ethynylpyridine) having glycidyl functionality was performed by the direct polymerization of 2-ethynylpyridine and epibromohydrin under mild reaction conditions without any initiator and catalysts. The polymerization proceeded well to give the resulting poly(2-ethynylpyridinium bromide) with a glycidyl functionality having relativity high molecular weight in high yields. The polymer structure was characterized by various instrumental methods to have the conjugated polymer backbone structure having glycidyl functionality. This ionic polymer was completely soluble in water, methanol, DMF, DMSO, and N,N-dimethylacetamide, but insoluble in THF, toluene, acetone, nitrobenzene, and n-hexane. This polymer system exhibited the UV-visible absorption around 300 and 520 nm and red photoluminescence spectrum around 725 nm.

• 한국실내디자인학회논문집
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• 제15권1호
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• pp.47-54
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• 2006

Stages, in the theatrical spaces, were space, which incorporates aspects of cities. Hence, the stages have been constituted to materialize sequence of city, which has exact number, proportion and order of ideal city. In addition, it has accomplished change, which depends on type of performance with the social condition and culture of generation, city has. However, the original form of theatrical space were forgotten on account of the various changes of theatrical form with modem movement since the end of 19th century, and theatrical space, which does not relate with its space of city, was started to constitute. Particularly in contemporary society, the theatre can give vitality to the citizens, and also theatrical architecture as a commercial code has been a general form, though it takes important role, which improves cultural value with technical improvement of cities development of society. Thus, this study analyzed urbanity ,which theatres have incorporated historically, and deduced a correlativity from to be based on constitution of space in visual, perceptual, spatial constitution and functional role. Focused on published SPAC international competition, it was interpreted by contemporary focus, therefore, this experiment suggests constitution of theatrical spaces of information, takes urbanity, through to analyze visual, perceptual, spatial constitution and functional role in context of contemporary city.

• 천문학회보
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• 제44권1호
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• pp.59.1-59.1
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• 2019

Immediate vicinity of a supermassive black hole (SMBH) is an important place to test general relativity in strong gravity regime. Also, this is a place where mass accretion and jet formation actively occurs at the centers of active galaxies. Theoretical studies predict presence of bright ring-like emission encircling an accreting SMBH with a diameter of about 5 Schwarzschild radii, and a flux depression at the center (i.e., BH shadow). Direct imaging of the BH shadow is accordingly of great importance in modern astrophysics. However, the angular sizes of the horizon-scale structures are desperately small (e.g., ~40-50 microarcseconds (uas) diameter for the nearest best candidates). This poses serious challenges to observe them directly. Event Horizon Telescope (EHT) is a global network of sensitive radio telescopes operating at 230 GHz (1.3 mm), providing ultra-high angular resolution of 20 uas by cutting-edge very long baseline interferometry techniques. With this resolution, EHT aims to directly image the nearest SMBHs; M87 and the galactic center Sgr $A{\ast}$ (~40-50 uas diameters). In Spring 2017, the EHT collaboration conducted a global campaign of EHT and multiwavelength observations of M87 and Sgr $A{\ast}$, with addition of the phased ALMA to the 1.3mm VLBI array. In this talk, I review results from past mm-VLBI and EHT observations, provide updates on the results from the 2017 campaign, and future perspectives.

• 천문학회보
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• 제46권2호
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• pp.43.5-44
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• 2021

In the local Universe, the gravitational effects of mass density fluctuations exert perturbations on galaxies' redshifts on top of Hubble's Law, called 'peculiar velocities'. These peculiar velocities provide an excellent way to test the cosmological model in the nearby Universe. In this talk, we present new cosmological constraints using peculiar velocities measured with the 2MASS Tully-Fisher survey (2MTF), 6dFGS peculiar-velocity survey (6dFGSv), the Cosmicflows-3 and Cosmicflows-4TF compilation. Firstly, the dipole and the quadrupole of the peculiar velocity field, commonly named 'bulk flow' and 'shear' respectively, enable us to test whether our cosmological model accurately describes the motion of galaxies in the nearby Universe. We develop and use a new estimators that accurately preserves the error distribution of the measurements to measure these moments. In all cases, our results are consistent with the predictions of the Λ cold dark matter model. Additionally, measurements of the growth rate of structure, fσ8 in the low-redshift Universe allow us to test different gravitational models. We developed a new estimator of the "momentum" (density weighted peculiar velocity) power spectrum and use joint measurements of the galaxy density and momentum power spectra to place new constraints on the growth rate of structure from the combined 2MTF and 6dFGSv data. We recover a constraint of fσ8=0.404+0.082-0.081 at an effective redshift zeff=0.03. This measurement is also fully consistent with the expectations of General Relativity and the Λ Cold Dark Matter cosmological model.

• Korean Journal of Acupuncture
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• 제21권4호
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• pp.145-156
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• 2004

Objective : The following study was undertaken in order to seek the acupuncture operation method of ${\ll}$Sang Han Lun(傷寒論)${\gg}$ Liu-Jing-Bian-Zheng(六經辨證). Methods : Based on the documents quoted in ${\ll}$Sang Hang Za Bing Lun.Xu Wen(傷寒雜病論 序文)${\gg}$ of 'Zhang, Zhong-Jing(張仲景)', the relativity of the theory of Jing-Mai(經脈) and Liu-Jing-Bian-Zheng of convalescence. Results : 1. ${\ll}$ Sang Han Lun${\gg}$ Liu-Jing-Bian-Zheng has succeeded and was developed based on Liu-Jing-Fen-Zheng(六經分證) of ${\ll}$Su Wen Re Lun(素問.熱論)${\gg}$. 2. Liu-Jing-Bing became the general principle of Fen-Jing(分經) and Ding-Zheng(定證) that may be applicable to Fenghan(風寒), Wenre(溫熱), Lili(역려) and Zabing(雜病). 3. Most commentators of ${\ll}$ Sang Han Lun${\gg}$ in the Song, Ming and Ching Dynasties of ${\ll}$ Sang Han Lun${\gg}$ interpreted the Liu-Jing-Bing in physiological and pathological aspects of Rong-Wei(榮衛)

• 대한수학회지
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• 제48권4호
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• pp.669-689
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• 2011

The notion of quasi-Einstein manifolds arose during the study of exact solutions of the Einstein field equations as well as during considerations of quasi-umbilical hypersurfaces. For instance, the Robertson-Walker spacetimes are quasi-Einstein manifolds. The object of the present paper is to study Lorentzian quasi-Einstein manifolds. Some basic geometric properties of such a manifold are obtained. The applications of Lorentzian quasi-Einstein manifolds to the general relativity and cosmology are investigated. Theories of gravitational collapse and models of Supernova explosions [5] are based on a relativistic fluid model for the star. In the theories of galaxy formation, relativistic fluid models have been used in order to describe the evolution of perturbations of the baryon and radiation components of the cosmic medium [32]. Theories of the structure and stability of neutron stars assume that the medium can be treated as a relativistic perfectly conducting magneto fluid. Theories of relativistic stars (which would be models for supermassive stars) are also based on relativistic fluid models. The problem of accretion onto a neutron star or a black hole is usually set in the framework of relativistic fluid models. Among others it is shown that a quasi-Einstein spacetime represents perfect fluid spacetime model in cosmology and consequently such a spacetime determines the final phase in the evolution of the universe. Finally the existence of such manifolds is ensured by several examples constructed from various well known geometric structures.

• 복식
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• 제59권1호
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• pp.14-28
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• 2009

Exoticism, by definition, is 'the charm of the unfamiliar', usually because of associations with a distant country. In the western-centric world, exoticism implies non-western or oriental style. The purpose of this study was to identify Koreans' perception of "Exoticism", and to compare the perception of exotic fashion image according to gender and education differences. Empirical study was composed of two parts focusing on gender and education effects respectively. For the first part, data were collected by self-administered questionnaires distributed to 280 respondents at 2 universities and 2 high schools during August and September 2005. The sample was consisted of 140 male and 140 female. A measurement, including 24 image adjectives to evaluate 16 fashion stimuli, was developed. Data were analyzed by descriptive statistics, correlations, t-test, and MDS. There was no difference in the perception of exotic fashion image according to gender. Both gender groups perceived exotic image as western image and non-exotic image as oriental image. Thus it could be said that Koreans perceive western-based fashion as foreign and exotic. This finding implies the relativity of "Exoticism." In the second part, the measurement and the analysis methods were the same with the first part. The respondents were consisted of 70 fashion majored female students and 70 non-fashion majored female students. There was considerable difference between fashion and non-fashion major groups in their perception of exotic fashion image. Whereas non-fashion major group perceived exotic image as western image and non-exotic image as oriental image, fashion major group perceived exotic image as both western and oriental image. This result suggested that fashion major group have western-centered conception as well as general perception character of Korean.