• Title/Summary/Keyword: relativity

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IRON LINE PROFILES FROM RELATIVISTIC ELLIPTICAL ACCRETION DISKS

  • CHANG HEON-YOUNG;CHOI CHUL-SUNG
    • Journal of The Korean Astronomical Society
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    • v.35 no.3
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    • pp.123-130
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    • 2002
  • An elliptical accretion disk may be formed by tidally disrupted debris of a flying-by star in an active galactic nucleus (AGN) or by tidal perturbation due to a companion in a binary black hole system. We investigate the iron K$\alpha$ line profiles expecting from a geometrically thin, relativistic, elliptical disk in terms of model parameters, and find that a broad and skewed line profile can be reproduced well. Its shape is variable to the model parameters, such as, the emissivity power-law index, the ellipticity of the disk, and the major axis orientation of the elliptical accretion disk. We suggest that our results may be useful to search for such an elliptical disk and consequently the tidal disruption event.

Creativity in medical education: concepts related to creative capacity

  • Kim, Yura;Lee, Young Hwan
    • Journal of Yeungnam Medical Science
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    • v.37 no.2
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    • pp.79-83
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    • 2020
  • In the 21st-century postmodernism era, which represents diversity and relativity, one of the most essential elements in the field of education is to strengthen individual human values. Accordingly, we must focus on developing capacity in order to adapt to change. It is clear that the medical field maximizes the need for new judgments to solve life-related problems constantly, and this problem-solving capacity is an essential skill for a physician. Problem-solving capacity can be achieved simultaneously with creativity to apply them in an appropriate manner based on standardized expertise and well-trained skills. Creativity is also a key element that medical education is currently pursuing. Many studies on creativity have resulted in confusion and misunderstandings on the concept of creativity due to similar terms and varied definitions, such as creation, innovation, etc. In this study, we attempt to identify the importance of creativity in medical education by comparing and organizing concepts related to creative capacity.

Falsifying LCDM: model-independent tests of the concordance model of cosmology

  • L'Huillier, Benjamin
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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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.

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Tess as Posthuman: Overturning Conventional Ideas in Tess of the D'Urbervilles (『테스』를 통해 본 포스트휴먼 시대의 인간)

  • Cho, Bu Min;Kim, Donguk
    • English & American cultural studies
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    • v.18 no.4
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    • pp.189-213
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    • 2018
  • This paper aims to show how Thomas Hardy overturns conventional ideas in opposition and eventually disrupts the hierarchical order of ideas in the Victorian society of Tess of the D'Urbervilles. Divided into four sections, such as feeling/reason, purity/impurity, femininity/masculinity, and death/life, it examines how these binaries are deconstructed in the heroine's tragic life journey. The heroine Tess of the book, who boldly crosses the boundaries marked by traditional society, turns her image as a fallen woman into that of divinity, erasing the boundary between evil and good. In doing so, Hardy leads the reader to question the system of established values and reveals the illegitimacy of absolute values, thence stressing what all one can grasp in this world is nothing else than an absence of a central value. The relativity of truth and the power of overturning established value systems advertised in the book have significant implications for today's readers as well as for the Victorians.

Thick Accretion Disk and Its Super Eddington Luminosity around a Spinning Black Hole

  • Jang, Uicheol;Kim, Hongsu;Yi, Yu
    • Journal of Astronomy and Space Sciences
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    • v.38 no.1
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    • pp.39-44
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    • 2021
  • In the general accretion disk model theory, the accretion disk surrounding an astronomical object comprises fluid rings obeying Keplerian motion. However, we should consider relativistic and rotational effects as we close in toward the center of accretion disk surrounding spinning compact massive objects such as a black hole or a neutron star. In this study, we explore the geometry of the inner portion of the accretion disk in the context of Mukhopadhyay's pseudo-Newtonian potential approximation for the full general relativity theory. We found that the shape of the accretion disk "puffs up" or becomes thicker and the luminosity of the disk could exceed the Eddington luminosity near the surface of the compact spinning black hole.

Riemann Solvers in Relativistic Hydrodynamics: Basics and Astrophysical Applications

  • IBANEZ JOSE MA.
    • Journal of The Korean Astronomical Society
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    • v.34 no.4
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    • pp.191-201
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    • 2001
  • My contribution to these proceedings summarizes a general overview on High Resolution Shock Capturing methods (HRSC) in the field of relativistic hydrodynamics with special emphasis on Riemann solvers. HRSC techniques achieve highly accurate numerical approximations (formally second order or better) in smooth regions of the flow, and capture the motion of unresolved steep gradients without creating spurious oscillations. In the first part I will show how these techniques have been extended to relativistic hydrodynamics, making it possible to explore some challenging astrophysical scenarios. I will review recent literature concerning the main properties of different special relativistic Riemann solvers, and discuss several 1D and 2D test problems which are commonly used to evaluate the performance of numerical methods in relativistic hydrodynamics. In the second part I will illustrate the use of HRSC methods in several astrophysical applications where special and general relativistic hydrodynamical processes play a crucial role.

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화이트헤드의 철학과 수학 교육

  • Yu, Chung-Hyun;Kim, Hye-Kyung
    • East Asian mathematical journal
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    • v.25 no.3
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    • pp.399-413
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    • 2009
  • Whitehead's philosophy is evaluated as an applicable philosophy and an accurate, logical explanation system about the world through mathematics. Whitehead's ideological development can be divided into mathematical research, critical consciousness about sciences and philosophical exploration. Although it is presented as a whole unified conceptual framework to understand nature and human beings which is based on modern mathematics and physics in the 20th century, Whitehead's philosophy has not been sufficiently understood and evaluated about the full meaning and mathematics educational values. In this paper, we study relations of Whitehead's philosophy and the mathematical education. Moreover, we study implicity of mathematical education.

A study for female college students of somatotype and MBTI personality type (여대생의 체형과 MBTI 성격유형에 관한 연구)

  • Kim, Jin-Ah;Lee, Jeong-Ran
    • Journal of Fashion Business
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    • v.14 no.1
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    • pp.11-26
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    • 2010
  • This study was carried out using personal measurement for female college students who have a great interest in fashion at 20-24 age, and examined somatotype character. As a means of a character type test, the grades were laid by using MBTI which proved to be objective, and relativity between character types was laid by conducting correlation analysis. The conclusions which can be drawn from this study are as followed. 1. In 4 preference index, which was classified by MBTI, Sensing(S) type was the highest of 17.27% at the average and 68.5% at the distribution rate each. The average of Extraversion(E) type was 14.56% and it's distribution rate was 64.5%. Index of types were : Intuition(N) 12.49%, Introversion(I) 11.75%, Perceiving(P) 12.50%. Average distribution rate of each types were : N 31.5%, I 35.5%, P 40.3%. And average of Sensing(S) type was the lowest, 11.09%. Like American Students, the subjects of this study showed higher in the E type than in the I type. The distribution rate of 16 character types of MBTI were : ESTJ 18.5%, ESFP 13.7%, ISTJ and ESFJ 9.7%. But INTP and INFP were low, 2.4% and 0.8%. 2. Average sizes of subjects for this study were : height 160.49cm, weight 51.83kg, bust 83.22cm, waist 65.49cm, hips 90.70cm. As compared with measurement of women at 20-24 age of Size Korea(2004), the subjects of this study showed less, about 0.2-5cm in height, 0.2-2cm in circumference except in waist, and 0.5-3.6cm in length. 3. After examining the relativity between personal measurement categories of the subjects and character type through the MBTI, Extraversion(E) type showed inverse correlation in stature, height, biacromial breadth, and subcutaneous fat thickness of posterior iliospinale. Contrary to the E type, the Introversion(I) type showed positive correlation. Sensing(S) type showed inverse correlation only in biacromial breadth, Intuition(N) type showed positive correlation in most categories including height, width and the subcutaneous fat thickness. Thinking(T) type showed positive correlation in bust point-bust point, chest depth and hip width. Feeling(F) type, on the other hand, showed inverse correlation. The Judging(J) type showed inverse correlation in stature, height, length and the parts of chest. In contrast, Perceiving(P) type showed positive correlation in other categories including biacromial breadth, same as the J type.

Relations between Normal Serum Gamma-glutamyltransferase and Risk Factors of Coronary Heart Diseases according to Age and Gender (연령과 성별에 따른 정상 혈청 Gamma-glutamyltransferase와 관상동맥질환 위험인자와의 관계)

  • Kwon, Se Young;Na, Young Ak
    • Korean Journal of Clinical Laboratory Science
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    • v.48 no.1
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    • pp.22-29
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    • 2016
  • Serum gamma-glutamyltransferase (GGT) has been widely used as a marker of alcohol intake and liver failure. Recently, the relativity between GGT and various diseases has been identified with growing interest. In this study, we examined relativity between GGT value and risk factors of coronary heart diseases among those with normal GGT value, excluding heavy drinkers. Specifically, we compared the differences based on age and gender. Data from the 2011 KNHNES were used (N=3,619). When the subjects were categorized according to quartile based on the serum GGT levels, there was 10~20, 21~27, 28~38, 39~71 IU/L in men, and 6~12, 13~16, 17~22, 23~42 IU/L in women. The mean of most variables was the highest in the $4^{th}$ quartile (Q4), however age and LDL Cholesterol were the highest in the $2^{nd}$ quartile (Q2) in men. The FRS and 10-year CHD risk was the highest in the $2^{nd}$ quartile in men, and the highest in the $4^{th}$ quartile in women. Increased GGT was correspondingly linked with age in women but age was the highest in GGT in the $2^{nd}$ quartile in men. In the 70's, the highest Q1 and Q2 was in men and the highest Q3 and Q4 in women. Although GGT value was within the normal range, increased GGT showed correlation with various risk factors. The FRS and 10-year CHD risk showed different patterns according to age and gender along with increased GGT value.

Citing Pattern Analysis based on Cited-by Linking Data of DOI Journals in the Field of Natural Sciences & Engineering (Cited-by Linking 데이터 기반 자연과학 및 공학 분야 학술논문 인용 패턴 분석)

  • Seo, Sun Kyung;Choi, Ho Nam;Kim, Byung-Kyu;Choi, Seon-Heui;Kim, Jeong Hwan
    • Journal of the Korean Society for information Management
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    • v.33 no.2
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    • pp.157-176
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    • 2016
  • Cited-by Linking Service is one of the CrossRef's information services that allows you to discover how your publications are being cited and to incorporate that information into your online publication platform. This study tries to investigate citation patterns in the field of both Natural Science and Engineering using all of DOI assigned articles and Cited-by Linking data which are accumulated and managed by KISTI. The investigating approach is designed to verify the theory of 1) cognitive accessibility, 2) 'perceived quality and significance' and 3) 'subject relativity'. For cognitive accessibility verification the fulltext language portion of Korean and English between "Cited DOI Source Data" and "NOT Cited DOI Source Data" was compared. For perceived quality and significance verification the availability of the "Cited DOI Source Data" and "NOT Cited DOI Source Data" from SCIE and SCOPUS was employed. For subject relativity DOI data were classified and analysed on the basis of OECD subject classification scheme. Findings are that global citability is closely related to the fulltext language of the articles and their quality and significance. And in the natural science field most of citations are from the same subject categories, while relatively more citations are from other subject categories in the engineering field.