• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.603-604
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• 2015

Standard thin disk theory predicts that an inner disk region dominated by radiation pressure is thermally unstable. However, this kind of instability isn't detected in the observations of X-ray binaries. In this work, we revisit this issue by investigating the stability of a thin disk with magnetically driven winds. It is found that the disk winds can help to make a thin disk stable by taking away most of the energy released in the disk, resulting in a much cooler disk. The disk can always be stable even for a very weak initial field strength ${\beta}_{p,0}{\leq}400$ when ${\alpha}=0.05$ and $B{\phi}=10B_p$ are adopted.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.43.2-43.2
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• 2018

The line-of-sight component in the relative motion of galaxy pairs sources the redshift space distortion (RSD) in galaxy surveys. By knowing the probability density function (PDF) of pair-wise motions and projecting it to the line-of-sight direction, one can compute the RSD effect precisely. I present the pair-velocity PDF of dark matter and galaxies in the Horizon-run 4 simulation. I also derive a model motivated by the perturbation theory which fits the results fairly well. I also discuss the application of the model in constraining the cosmology.

• The Journal of Korean Philosophical History
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• no.35
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• pp.385-413
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• 2012

This thesis is a study on the relation of between Xiangshu Zhouyi Theory and mathematics, Zhouyi Theory as the one of the study of Chinese classics, was formed by Zhouyi' Eight Diagrams, the theory of Yinyangwuxing and the knowledge of natural science in Han dynasty. 'Xiangshu' had been regarded as the important concept and theory in the history of Zhouyi Theory From the beginning of Han dynasty to the end of Qing dynasty. At this developing of this Periodical Change, 'Xiangshu' had been endoded in the expression system of mathematics. This thesis considers binary system and surplus nembers, multiple and progression, magic square and circular constant, a proportional expression from Zhouyi Theory point of view. Xiangshu Zhouyi theory got the answer of these questions like the origin of Zhouyi, interpreting Guayao-word and Cosmology by using those expression systems of mathematics. Besides mathematics, Xiangshu Zhouyi theory was also related to astronomy, medicine, etc. Xiangshu Zhouyi theory had kept the pace with the general development of natural science. This thesis from the premise that Xiangshu Zhouyi theory kept the pace with natural science, summing up the mathematical expression system in the history of Zhouyi theory, proves that Xiangshu Zhouyi theory had developed according as the conditions of natural science.

• Journal of the Daesoon Academy of Sciences
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• v.33
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• pp.31-62
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• 2019

The purpose of this article is to study on the Daesoon Cosmology of the Correlative Relation between Mugeuk and Taegeuk. Daesoon cosmology is a cosmology based on the juxtaposition between the Gucheon Sangje and the world. In this article, I would like to say that this theory in Daesoon Thought was developed in three stages: the phase of the Mugeuk Transcendence of Gucheon Sangje, the stage of the Taegeuk Immanence, and the phase of the Grand Opening of the Later World between Mugeuk and Taegeuk as a correlative gentle reign. First of all, the phase of the Mugeuk Transcendence of Gucheon Sangje has been revealed as a yin-yang relationship. The stage of the Taegeuk Immanence represents the togetherness of harmony and co-prosperity between yin and yang, and the phase of the Grand Opening of the Later World between Mukeuk and Taegeuk refers to the unshakable accomplishment of its character and energy. It will be said that this is due to the practical mechanism in the correct balance of yin-yang making a four stage cycle of birth, growth, harvest, and storage. In addition, the Daesoon stage of the settlement of yin and yang is revealed as a change in the growth of all things and the formation of the inner circle. The mental growth reveals the characteristics of everything in the world, each trying to shine at the height of their own respective life as they grow up energetically. The dominant culture of cerebral communion renders a soft and elegant mood and combines yin and yang to elevate the heavenly and earthly period through transcendental change into sympathetic understanding. The stage of the Grand Opening of the Later World between Mugeuk and Taegeuk is one of the earliest days of the lunar month and also the inner circle of Taegeuk. It is in line with Ken Wilbur's integrated model as a step to the true degrees to develop into a world with brightened degrees. It is a beautiful and peaceful scene where celestial maidens play music, the firewood burns, and the scholars command thunder and lightning playfully. Human beings achieve a state of happiness as a free beings who lives as gods upon the earth. This is the world of theGrand Opening of the Later World between Mugeuk and Taegeuk. Daesoon Thought was succeeded by Dojeon in 1958, when Dojeon emerged as the successor in the lineage of religious orthodoxy and was assigned the task of handling Dao in its entirety. In addition, Daesoon is a circle and represents freedom and commonly shared happiness among the populous. Cosmology in the Daesoon Thought will enable us to understand deep dimensions and the identity of members as individuals within an inner circle of correlation between transcendence and immanence. This present study tries to analyze the public effects philologically and also the mutual correlation by utilizing the truthfulness of literature and rational interpretation. The outlook for the future in Daesoon Thought also leads to the one-way communication of Daesoon as a circle.

• (The)Study of the Eastern Classic
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• no.66
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• pp.251-276
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• 2017

This article is an attempt to identify the difference between "Oneness between Heaven and Man(天人合一)" thought proposed by Zhoudunyi(周敦?) in 'Taijirushuo(太極圖說)' and "Cheon-In-Sim-Seong-Haap-Il(A diagram about Unifying Heaven, Human, and Mind-and-Heart)(天人心性合一)" thought presented by Kwonkun(權近) in 'Ip-Hak-Do-Seol(入學圖說)'. Oneness between Heaven and Man thought, which have developed into practical ideas centered on self-cultivation theory, have a philosophical depth and logical system by Zhoudunyi(周敦?) with 'Taijirushuo(太極圖說)' in order to summarize the metaphysical cosmology and the treatise of human nature in Dynasty Song. Zhoudunyi established the concept of Wuji(無極) corresponding to Heaven(天), and suggested unified cosmology of 'Wuji(無極)-Taiji(太極)-Yin and Yang(陰 陽)-Five elements(五行)-Human(人間)-Everything(萬物)'. His cosmology is the perception that heaven, the creator of all things, is the relationship of unity, which is connected by man as the creature and the Order(命)and Nature(性). Thus, when people restores one's nature and realized that it is a mandate from Heaven, he said that heavenly unity can be realized and become a Saint(聖人). The idea of Zhoudunyi(周敦?) comes to Zhu Xi(朱熹) about 120 years later and it is concluded to be converged the Neo-Confucianism with Lichi theory. Accordingly, Zhoudunyi(周敦?) is evaluated as the master of the Neo-Confucianism to posterity. KwonKun suggested the idea of "Cheon-In-Sim-Seong-Haap-Il(A diagram about Unifying Heaven, Human, and Mind-and-Heart)(天人心性合一)" in 'Ip-Hak-Do-Seol(入學圖說)' at the end of Goryeo Dynasty. KwonKun's "Cheon-In-Sim-Seong-Haap-Il" thought is logically coherent by adding an element of the doctrines of Chu-tzu to his teacher Yi Saek's "Chun-In-Mu-Gan" and arranging that the functions of my mind and Li(理) are all together. Whereas Zhuodunyi is concerned with the creation principle of the universe and all things, KwonKun mainly cares about Heaven(天), Human(人), and Heart (心), and Nature(性) in the view of psychology. In addition, he suggested that "Cheon-In-Sim-Seong-Haap-Il" can be achieved by self-cultivation centered of Gyeong-thought(敬思想). The idea of KwonKun has become a stepping stone to the development of the doctrines of Chu-tzu based on psychology. His ideas came to Yi Hwang about 150 year later, and are integrated into four clue-seven emotion (Sadan Chiljung四端七情) thesis and Gyeong-thought(敬思想). However, unlike the Zhoudunyi, KwonKun is not properly evaluated despite his academic accomplishments.

• Journal of The Korean Astronomical Society
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• v.37 no.5
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• pp.597-600
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• 2004

A substantial number of processes have been suggested as possible contributors to the extragalactic $\gamma$-ray background (EGRB). Yet another contribution to this background will be emission produced in hadronic interactions of cosmic-ray protons with the cluster thermal gas; this class of cosmic rays (CRs) has been shown to be responsible for the EUV emission in the Coma Cluster of galaxies. In this paper we assume the CRs in the Coma Cluster is prototypic of all clusters and derive the contribution to the EGRB from all clusters over time. We examine two different possibilities for the scaling of the CR flux with cluster size: the number density of the CRs scale with the number density of the thermal plasma, and alternatively, the energy density of the CRs scale with the energy density of the plasma. We find that in all scenarios the EGRB produced by this process is sufficiently low that it will not be observable in comparison with other mechanisms that are likely to produce an EGRB.

• Journal of The Korean Astronomical Society
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• v.47 no.3
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• pp.87-98
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• 2014

We develop a parallel cosmological hydrodynamic simulation code designed for the study of formation and evolution of cosmological structures. The gravitational force is calculated using the TreePM method and the hydrodynamics is implemented based on the smoothed particle hydrodynamics. The initial displacement and velocity of simulation particles are calculated according to second-order Lagrangian perturbation theory using the power spectra of dark matter and baryonic matter. The initial background temperature is given by Recfast and the temperature uctuations at the initial particle position are assigned according to the adiabatic model. We use a time-limiter scheme over the individual time steps to capture shock-fronts and to ease the time-step tension between the shock and preshock particles. We also include the astrophysical gas processes of radiative heating/cooling, star formation, metal enrichment, and supernova feedback. We test the code in several standard cases such as one-dimensional Riemann problems, Kelvin-Helmholtz, and Sedov blast wave instability. Star formation on the galactic disk is investigated to check whether the Schmidt-Kennicutt relation is properly recovered. We also study global star formation history at different simulation resolutions and compare them with observations.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.53.2-53.2
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• 2011

We combine the physics of the ellipsoidal collapse model with the excursion set theory to study the shapes of dark matter halos. In particular, we develop an analytic approximation to the nonlinear evolution that is more accurate than the Zeldovich approximation; we introduce a planar representation of halo axis ratios, which allows a concise and intuitive description of the dynamics of collapsing regions and allows one to relate the final shape of a halo to its initial shape; we provide simple physical explanations for some empirical fitting formulae obtained from numerical studies. Comparison with simulations is challenging, as there is no agreement about how to define a non-spherical gravitationally bound object. Nevertheless, we find that our model matches the conditional minor-to-intermediate axis ratio distribution rather well, although it disagrees with the numerical results in reproducing the minor-to-major axis ratio distribution. In particular, the mass dependence of the minor-to-major axis distribution appears to be the opposite to what is found in many previous numerical studies, where low-mass halos are preferentially more spherical than high-mass halos. In our model, the high-mass halos are predicted to be more spherical, consistent with results based on a more recent and elaborate halo finding algorithm, and with observations of the mass dependence of the shapes of early-type galaxies. We suggest that some of the disagreement with some previous numerical studies may be alleviated if we consider only isolated halos.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.72.3-73
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• 2021

Baryon Acoustic Oscillations (BAO) are caused by acoustic density waves in the early universe and act as a standard ruler in the clustering pattern of galaxies in the late Universe. Measuring the BAO feature in the 2-point correlation function of a sample of galaxies allows us to estimate cosmological distances to the galaxies mean redshift, , which is important for testing and constraining the cosmology model. The BAO feature is also expected to appear in the higher order statistics. In this work we measure the generalized spatial N-point point correlation functions up to 4th order. We made measurements of the 2, 3, and 4-point correlation functions in the SDSS-III DR12 CMASS data, comprising of 777,202 galaxies. The errors and covariances matrices were estimated from 500 mock catalogues. We created a theoretical model for these statistics by measuring the N-point functions in halo catalogues produced by the approximate Lagrangian perturbation theory based simulation code, PINOCCHIO. We created simulations using initial conditions with and without the BAO feature. We find that the BAO is detected to high significance up to the 4-point correlation function.

• Journal of the Korea Fashion and Costume Design Association
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• v.18 no.3
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• pp.165-181
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• 2016

This study looks into the Korean traditional costume formation and the thoughts of the Korean people that form the foundation of that Korean traditional costume formation. And the goal of this study is in linking the thoughts and formative characteristics reflected in the Korean traditional costume formation to the fractal geometry, in an attempt to reveal correlation between Korean traditional costume formation which have existed for thousands of years to contemporary science of the West. The fractal theory that appeared as the new paradigm of contemporary science displayed similarities with the traditional ideologies of Korea, and the fact that formation principles of fractal appear in the formation of Korean costume, formed based on the Korean ideologies, show magnanimous capacity of the traditional Korean culture. When we look at the concept of fractal, the word fractal refers to the structure in which the shape repeats, where small structure is similar to the whole structure in form in endlessly repeating structure. In other words, 'fractal' means a structure that geometrically untangles the concept of 'self-similarity' which possesses the same shape in parts and in whole, and its major characteristics include 'self-similarity', 'circularity' and 'repeatability'. Korean costumes were formed based on the Han-thoughts, with a structure that possesses parts within the whole and the whole within parts, in accordance with the self-similarity theory of 'fractal'. This study compared studied fractal phenomenon which appear in formation characteristics of Korean traditional costume, which were formed based on the Korean traditional ideology, in other words, Korean costume formation and formation principles of fractal geometry were compared studied.