• The Bulletin of The Korean Astronomical Society
• /
• v.39 no.1
• /
• pp.36.1-36.1
• /
• 2014

The correlation between mass of Type Ia Supernova (SN Ia) host galaxies and Hubble residual is now well-established. The origin of this relation, however, is yet to be understood. We have used low-resolution spectra of early-type hosts from YONSEI (YOnsei Nearby Supernovae Evolution Investigation) project to measure central velocity dispersion and Lick/IDS absorption indices. By using the Evolutionary Population Synthesis (EPS) models, luminosity-weighted mean age and metallicity of host galaxies were determined from $H{\beta}$ and absorption lines. Here we will discuss the correlation between the velocity dispersion, which indicates the mass of galaxies, and mean age of stellar population in our sample of early-type host galaxies.

• The Bulletin of The Korean Astronomical Society
• /
• v.41 no.1
• /
• pp.66.4-67
• /
• 2016

Our recent investigation (Lee et al. 2015) suggests that the presence of double red clump in the Milky Way bulge is another manifestation of multiple populations observed in halo globular clusters. The origin of Helium enhancement in the 2nd generation population (G2), however, is not yet fully understood. Here we investigate the origin of this super-Helium-rich population in the framework of self-enrichment scenario. We find that chemical enrichments and pollutions by asymptotic giant branch stars and winds of massive rotating stars can naturally reproduce the observed Helium enhancement. The Helium to metal enrichment ratio appears to be ${\Delta}Y/{\Delta}Z=6$ for G2, while the standard ratio, ${\Delta}Y/{\Delta}Z=2$, is appropriate for G1, which is probably enriched mostly by typeII supernovae.

• The Bulletin of The Korean Astronomical Society
• /
• v.38 no.2
• /
• pp.62.2-62.2
• /
• 2013

Recent spectroscopic observations have provided evidence for complex chemical evolution by supernovae and/or asymptotic giant branch (AGB) stars in the two metal-poor globular clusters (GCs) NGC2419 and M15. In particular, the horizontal branches (HBs) of these metal-poor GCs are very extended in the Hertzsprung-Russell diagram. The origin of these peculiar features, as well as that for the Sandage period-shift effect observed in these clusters, are yet to be understood. Here we show, by constructing population models including the Nitrogen enhanced subpopulation, that the second generation populations in these clusters would be enhanced not only in Helium, but also in Nitrogen. This working hypothesis can simultaneously explain the observed extended feature on the HB and the period-shift of RR Lyrae variables.

• Journal of Technology Innovation
• /
• v.5 no.1
• /
• pp.113-149
• /
• 1997

This paper, searching for the origin of the science and technology policy, is one of the research series on the original form of current S&T policy such as origin, evolution and changing patterns. Without understanding the origin, it is very difficult to understand the evolution and the current change of the policy. To answer this question, 2 kinds of conditions are set: 4 concepts for the origin of a policy and also 4 conditions for the S&T policy itself. As the origin of a policy, 4 concepts are set such as independence, continuance, diffusion and modern state as a policy body. Also as conditions for S&T policy, there may be 4 conditions such as policy targets, policy functions, administration body and the usage of the name of the policy. S&T can be distinguished as science, technology and S&T along it's development path. There, hence, are 2 origins of science and technology policy. French policy for modern science at the late 18th century and the establishment of the Agency of Science and Technology Policy of Japan in 1956 can be pointed out as the origin of the policy. The former can be called as the origin for natural science, and the latter as the origin for S&T. This study implies that new paradigm of S&T policy is a reflection for both the needs of new S&T and social needs. When there were big problems in a society and when there appeared new S&T, they exploited new S&T vigorously. This has been remained as a rememberable monuments in the history of the S&T policy.

• The Bulletin of The Korean Astronomical Society
• /
• v.40 no.1
• /
• pp.79.2-79.2
• /
• 2015

The $M_{BH}-{\sigma}$ relation for galaxies is a stand-out illustration of the co-evolution of galaxies and their central supermassive black holes (SMBHs); however, how this co-evolution occurs and whether this relation holds for SMBHs of the early universe is still a matter of debate. In order to study this at higher redshifts, quasi-stellar objects (QSOs) are the best targets, due to their large sample size and effective $M_{BH}$ estimation. Nevertheless, it is difficult to examine properties of their host galaxies, simply due to the sheer brightness of the QSO itself. Here, we discuss a distinctive method in studying these QSO host galaxies, via gravitational lensing (GL). GL offers a unique approach in determining the mass of the lens object, in this case the host galaxy. QSOs from the SDSS quasar catalog were searched in the Hubble Space Telescope archives, and GL features around them were visually inspected. One such candidate is SDSS J1114-00; to increase its robustness as a GL system candidate, it was observed with the Inamori-Magellan Areal Camera & Spectrograph (IMACS) on the Magellan Baade Telescope at Las Campanas Observatory, to check whether the GL features have identical colors, meaning they are likely to originate from the same source. After confirmation of such GL systems, a sufficiently large sample will enable us to examine the $M_{BH}-{\sigma}$ relation at various redshifts, and in turn, investigate the co-evolution of SMBHs and their host galaxies.

• The Bulletin of The Korean Astronomical Society
• /
• v.42 no.1
• /
• pp.49.1-49.1
• /
• 2017

In order to investigate the origin of multiple stellar populations in the halo and bulge of the Milky Way, we have constructed chemical evolution models for the low-mass proto-Galactic subsystems such as globular clusters (GCs). Unlike previous studies, we assume that supernova blast waves undergo blowout without expelling the pre-enriched gas, while relatively slow winds of massive stars, together with the winds and ejecta from low and intermediate mass asymptotic giant branch stars, are all locally retained in these less massive systems. We first applied these models to investigate the origin of super-helium-rich red clump stars in the metal-rich bulge as recently suggested by Lee et al. (2015). We find that chemical enrichments by the winds of massive stars can naturally reproduce the required helium enhancement (dY/dZ = 6) for the second generation stars. Disruption of these "building blocks" in a hierarchical merging paradigm would have provided helium enhanced stars to the bulge field. Interestingly, we also find that the observed Na-O anticorrelation in metal-poor GCs can be reproduced, when multiple episodes of starbursts are allowed to continue in these subsystems. Specific star formation history with decreasing time intervals between the stellar generations, however, is required to obtain this result, as would be expected from the orbital evolution of these subsystems in a proto-Galaxy. The "mass budget problem" is also much alleviated by our models without ad-hoc assumptions on star formation efficiency and initial mass function.

• The Bulletin of The Korean Astronomical Society
• /
• v.43 no.1
• /
• pp.46.1-46.1
• /
• 2018

In order to investigate the origin of multiple stellar populations in the halo and bulge of the Milky Way, we have constructed chemical evolution models for the low-mass proto-Galactic subsystems such as globular clusters. Unlike previous studies, we assume that supernova blast waves undergo blowout without expelling the pre-enriched gas, while relatively slow winds of massive stars, together with the winds and ejecta from low and intermediate mass asymptotic-giant-branch stars, are all locally retained in these less massive systems. We find that the observed Na-O anti-correlations in metal-poor GCs can be reproduced when multiple episodes of starbursts are allowed to continue in these subsystems. A specific form of star formation history with decreasing time intervals between the stellar generations, however, is required to obtain this result, which is in good agreement with the parameters obtained from our stellar evolution models for the horizontal-branch. The "mass budget problem" is also much alleviated by our models without ad-hoc assumptions on star formation efficiency and initial mass function. We also applied these models to investigate the origin of super helium-rich red clump stars in the metal-rich bulge as recently suggested by Lee et al. (2015). We find that chemical enrichments by the winds of massive stars can naturally reproduce the required helium enhancement (dY/dZ = 6) for the second-generation stars. Disruption of proto-globular clusters in a hierarchical merging paradigm would have provided helium enhanced stars to the bulge field.

• The Journal of the Korea Contents Association
• /
• v.21 no.6
• /
• pp.445-455
• /
• 2021

Interest in the origin of the universe and man has historically been one of the central themes of human inquiry. The question of origin is not just a matter of intellectual curiosity, but a matter of human identity and an important matter of human destiny. The traditional model presented in relation to the origin of man is largely the Christian creationism that all things originated from the Creator, the evolutionary theory that everything happened by chance and evolved from lower to higher animals, and the agnosticism that we cannot know anything about the origin. This study deals with the theory of theistic evolution, a combination of creationism and evolutionism. It is argued that the theory of the evolutionary origin was not an immediate creation, although all things originated from God, but through creation through a long evolutionary process. The theory of theistic evolution was proposed by combining two conflicting theories of origin in a Christian way, which has several essential problems, but this study pointed out two. First, the God of the Bible is reduced to the image of being confined to the laws of nature, not the Almighty Creator. Second, by interpreting the events of the Bible symbolically, it results in rejection of historicity. Therefore, it is more rational to choose either evolutionism or creationism rather than the theory of theistic evolution.

• Asian Pacific Journal of Cancer Prevention
• /
• v.16 no.6
• /
• pp.2119-2128
• /
• 2015

Cancer is the leading cause of death around the world. Anticancer activities from many functional food sources have been reported in years, but correlation between cancer prevalence and types of food with anticancer activities from crop origin center in the world as well as food source with human migration are unclear. Hunger from food shortage is the cause of early human evolution from Africa to Asia and later into Eurasia. The richest functional foods are found in crop origin centers, housing about 70% in the world populations. Crop origin centers have lower cancer incidence and mortality in the world, especially Central Asia, Middle East, Southwest China, India and Ethiopia. Asia and Africa with the richest anticancer crops is not only the most important evolution base of humans and origin center of anticancer functional crop, but also is the lowest mortality and incidence of cancers in the world. Cancer prevention of early human migrations was associated with functional foods from crop origin centers, especially Asia with four centers and one subcenter of crop origin, accounting for 58% of the world population. These results reveal that coevolution between human's anticancer activities associated with functional foods for crop origin centers, especially in Asia and Africa.

• The Bulletin of The Korean Astronomical Society
• /
• v.42 no.1
• /
• pp.48.3-48.3
• /
• 2017

In our recent investigation of the Oosterhoff dichotomy among globular clusters (GCs), we have shown that the RR Lyrae variables in the Oosterhoff groups I, II, and III are produced mostly by first, second, and third generation stars (G1, G2, and G3), respectively. Unlike GCs, RR Lyrae stars in the Local Group dwarf galaxies show Oosterhoff-intermediate characteristics. The origin of this, however, is yet to be understood. In this poster, we will present our progress in understanding the origin of this phenomenon.