• Bulletin of the Korean Chemical Society
• /
• v.31 no.1
• /
• pp.196-198
• /
• 2010

• The Bulletin of The Korean Astronomical Society
• /
• v.38 no.1
• /
• pp.29.2-29.2
• /
• 2013

The presence of dark energy, suggested from Type Ia supernovae (SNe) cosmology, is the most pronounced astronomical discovery made during the past decade. The basic assumption of this discovery is that the look-back time evolution of SNe luminosity would be negligible after light-curve correction. Several recent works, however, show that there are some differences in Hubble residual among host galaxies having different morphology and mass, indicating that SNe luminosity might be affected by population age. In order to investigate this more directly, we are continuing the YONSEI (YOnsei Nearby Supernovae Evolution Investigation) project, where we are obtaining low-resolution spectra of some 60 nearby early-type host galaxies. The early-type galaxies are preferred because the mean population ages and metallicities can be estimated from the absorption lines, and they are less affected by dust extinction. In this talk, we will report our progress in determining the ages and metallicities of host galaxies to investigate their correlation with the Hubble residual.

• Journal of Astronomy and Space Sciences
• /
• v.34 no.3
• /
• pp.183-197
• /
• 2017

We present simulations of the optical-band images of high-redshift galaxies utilizing 845 near-ultraviolet (NUV) images of nearby galaxies obtained through the Galaxy Evolution Explorer (GALEX). We compute the concentration (C), asymmetry (A), Gini (G), and $M_{20}$ parameters of the GALEX NUV/Sloan Digital Sky Survey r-band images at z ~ 0 and their artificially redshifted optical images at z = 0.9 and 1.6 in order to quantify the morphology of galaxies at local and high redshifts. The morphological properties of nearby galaxies in the NUV are presented using a combination of morphological parameters, in which early-type galaxies are well separated from late-type galaxies in the $G-M_{20}$, $C-M_{20}$, A-C, and $A-M_{20}$ planes. Based on the distribution of galaxies in the A-C and $G-M_{20}$ planes, we examine the morphological K-correction (i.e., cosmological distance effect and bandshift effect). The cosmological distance effect on the quantitative morphological parameters is found to be significant for early-type galaxies, while late-type galaxies are more greatly affected by the bandshift effect. Knowledge of the morphological K-correction will set the foundation for forthcoming studies on understanding the quantitative assessment of galaxy evolution.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.10
• /
• pp.3793-3795
• /
• 2011

• Journal of The Korean Astronomical Society
• /
• v.36 no.3
• /
• pp.241-248
• /
• 2003

Owing to several observational evidences and theoretical predictions for morphological evolution of galaxies, it is now widely accepted that galaxies do evolve from late types to early ones along the Hubble sequence. It is also well established that non-axisymmetric potentials of bar-like or oval mass distributions can change the morphology of galaxies significantly during the Hubble time. Here, we review the observational and theoretical grounds of the secular evolution driven by bar-like potentials, and present the results of SPH simulations for the response of the gaseous disks to the imposed potentials to explore the secular evolution in the central regions of barred galaxies.

• Animal Systematics, Evolution and Diversity
• /
• v.7 no.1
• /
• pp.101-110
• /
• 1991

Two species of Perlidae, Oyamia coreana and Kiotina decorata which were collected in mountain valley of the Chonnam, Chonguk and Kyongnam provinces, south Korea are reported for the first time from Korea, with description of the external morphology of their eggs by SEM.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.9 no.3
• /
• pp.172-177
• /
• 2009

In this paper, a new morphology-based homomorphic filtering technique is presented to enhance features in medical images. The homomorphic filtering is performed based on the morphological sub-bands, in which an image is morphologically decomposed. An evolutionary design is carried to find an optimal gain and structuring element of each sub-band. As a search algorithm, Differential Evolution scheme is utilized. Simulations show that the proposed filter improves the contrast of the interest feature in medical images.

• Animal Systematics, Evolution and Diversity
• /
• v.8 no.2
• /
• pp.331-336
• /
• 1992

The occurrence of Enoploteuthis (Paraenoploteuthis) chunii in the Korean waters, and the following points were reported: 1. morphological variation of the protective membrane in the hectocotylized arm and 2. morphology of the spermatophore.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.19 no.5
• /
• pp.242-245
• /
• 2009

AlN crystals were grown by a sublimation process without seed crystals and the growth morphology of them was characterized. The grown AlN crystals were a polycrystalline phase, which had a diameter of $60\sim200\;{\mu}m$ and were grown with a growth rate of $0.2\sim0.5\;{\mu}n/hr$. It was observed that the as-grown crystals had a hexagonal crystal structure and revealed that these crystals were grown with a morphology of columnar morphology in the initial stage of the growth before they were enlarged in a way of a lateral growth behavior in the final stage. On the surface, a lot of pinholes were observed on the surface of crystals grown. The evolution of a growth morphology was characterized by optical and scanning electron microscopic observation.

• Animal Systematics, Evolution and Diversity
• /
• v.7 no.2
• /
• pp.233-240
• /
• 1991

The morphology and ecology of the marine hypotrichous ciliate, Oxytricha saltans (Cohn, 1866) Kahl, 1932 collected from shrimp culturing pond of Qingdao (Tsingtao, 36$^{\circ}$08'N : 120$^{\circ}$43'E) , P.R. China were investigated. collected samples were observed directly and we also observed cultured ones and stained specimens. In relation to this species were described the morphology and infraciliature in detail using protargol method, presented a new diagnosis and discussed some synonyms and the related species, Actinotricha saltans sensu Dragesco, 1963.