• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.149-151
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• 2005

We have studied the environmental effect on optical-NIR color gradients of 273 nearby elliptical galaxies. Color gradient is a good tool to study the evolutionary history of elliptical galaxies, since the steepness of the color gradient reflects merging history of early types. When an elliptical galaxy goes through many merging events, the color gradient can be get less steep or reversed due to mixing of stars. One simple way to measure color gradient is to compare half-light radii in different bands. We have compared the optical and near infrared half-light radii of 273 early-type galaxies from Pahre (1999). Not surprisingly, we find that $r_e(V)s$ (half-light radii measured in V-band) are in general larger than $r_e(K)s$ (half-light radii measured in K-band). However, when divided into different environments, we find that elliptical galaxies in the denser environment have gentler color gradients than those in the less dense environment. Our finding suggests that elliptical galaxies in the dense environment have undergone many merging events and the mixing of stars through the merging have created the gentle color gradients.

• Journal of The Korean Astronomical Society
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• v.43 no.4
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• pp.105-113
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• 2010

We study the dynamical evolution of the M87 globular cluster (GC) system using the most advanced and realistic Fokker-Planck (FP) model.By comparing our FP models with both mass function (MF) and radial distribution (RD) of the observed GC system, we find the best-fit initial (at M87's age of 2-3 Gyr) MF and RD for three GC groups: all GCs, blue GCs, and red GCs. We estimate the initial total mass in GCs to be $1.8^{+0.3}_{-0.2}{\times}10^{10}M_{\bigodot}$, which is about 100 times larger than that of the Milky Way GC system. We also find that the fraction of the total mass currently in GCs is 34\%. When blue and red GCs are fitted separately, blue GCs initially have a larger total mass and a shallower radial distribution than red GCs. If one assumes that most of the significant major merger events of M87 have ended by the age of 2-3 Gyr, our finding that blue (metal-poor) GCs initially had a shallower radial distribution supports the major merger scenario for the origin of metallicity bimodality.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.06a
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• pp.163-165
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• 2014

In this paper, we propose a world's first programmable video processing platform for video quality enhancement of 8K ($7680{\times}4320$) UHD (Ultra High Definition) TV at 60 frames per second. To support huge computation and memory bandwidth of video quality enhancement for 8K resolution, the proposed platform has unique features like symmetric multi-cluster architecture for data partitioning, ring data-path between clusters to support data pipelining, on-the-fly processing architecture to reduce DDR bandwidth, flexible hardware to accelerating common kernel in video enhancement algorithms. In addition to those features, general programmability of SRP (Samsung reconfigurable processor) as main core of the proposed platform makes it possible to upgrade continuously video enhancement algorithm even after the platform is fixed. This ability is very important because algorithms for 8K DTV is under development. The proposed sub-system has been embedded into SoC (System on Chip) and new 8K UHD TV using the programmable SoC is expected at CES2015 for the first time in the world.

• The Korean Journal of Cytopathology
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• v.16 no.1
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• pp.41-46
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• 2005

Carcinoid tumors of the thymus are vanishingly rare, and the characteristic cytologic findings of this condition have never before been reported in Korea. Recently, we encountered a 58-year-old woman who had been suffering from general weakness and weight loss for several months. Radiological imaging revealed a large anterior mediastinal mass. A fine needle aspiration biopsy (FNAB) of the mass showed predominantly scattered single cells, as well as some loose clusters of small cells with scanty cytoplasm. Some of these small cells exhibited plasmacytoid features, with moderately granular cytoplasm. We also discuss the cytological differential diagnosis between thymic carcinoid and other mediastinal tumors.

• Journal of Astronomy and Space Sciences
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• v.31 no.2
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• pp.121-130
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• 2014

Essential ideas, successes, and difficulties of Areal Density Analysis (ADA) for color-magnitude diagrams (CMD's) of resolved stellar populations are examined, with explanation of various algorithms and strategies for optimal performance. A CMD-generation program computes theoretical datasets with simulated observational error and a solution program inverts the problem by the method of Differential Corrections (DC) so as to compute parameter values from observed magnitudes and colors, with standard error estimates and correlation coefficients. ADA promises not only impersonal results, but also significant saving of labor, especially where a given dataset is analyzed with several evolution models. Observational errors and multiple star systems, along with various single star characteristics and phenomena, are modeled directly via the Functional Statistics Algorithm (FSA). Unlike Monte Carlo, FSA is not dependent on a random number generator. Discussions include difficulties and overall requirements, such as need for fast evolutionary computation and realization of goals within machine memory limits. Degradation of results due to influence of pixelization on derivatives, Initial Mass Function (IMF) quantization, IMF steepness, low Areal Densities ($\mathcal{A}$), and large variation in $\mathcal{A}$ are reduced or eliminated through a variety of schemes that are explained sufficiently for general application. The Levenberg-Marquardt and MMS algorithms for improvement of solution convergence are contained within the DC program. An example of convergence, which typically is very good, is shown in tabular form. A number of theoretical and practical solution issues are discussed, as are prospects for further development.

• Knowledge Management Research
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• v.17 no.3
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• pp.1-21
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• 2016

To attract visitors, it is essential to make destinations understandable by developing appropriate destination image. However, managing destination image properly is very complicated in order to induce visitors. In this study, the perceived destination image of backpackers who stay in guesthouse located in Seoul is explored. The purpose of the study was to examine the image of Seoul as a tourism destination. To this end, Q methodology, a technique designed for the systematic study of subjectivity in terms of beliefs, opinions, and attitudes is employed. More specifically, the statements representing different destination images perceived by sampled backpacking visitors were Q-sorted. Results showed that four different clusters of sampled backpacking visitors present four different perceived images accordingly: Seoulizer, Patternaizer, Utilizer, and Socializer. The results of this study imply that backpackers provide idiosyncratic perceptions of destination image, which are different from those offered by general travelers who are less sensitive to travel budgets. In addition, for tourism management, based on this study's results, destination marketing planners are encouraged to perform knowledge management, develop more appropriate plans and customized marketing strategies according to different perceived destination images of backpackers.

• Child Health Nursing Research
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• v.8 no.1
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• pp.110-120
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• 2002

A phenomenological study is conducted to investigate the experience of mothers with very low birth weight. Sample of 8 mothers participate. Seven theme clusters emerge when the formulated meanings were organized into categories. The participants are 8 mothers who gave birth in the general hospital located in Kyunggi-Province and still live there. The data are collected from the intensive interviews on the experience of mothers whose baby is very low birth weight infant. Data collection is through in depth personal interviews two or three times with each mother. On the basis of the meanings of the experience of mothers with very low birth weight infant, the seven essential themes have been obtained Theme 1:Being surprised and perplexed due to the unexpected sudden delivery Theme 2:Experiencing emotional pain such as anxiety, sorrow, fear, confusion and self-blaming caused by a small and feeble baby. Theme 3: Pouring all their time and efforts into the baby under the acute tension Theme 4:Undergoing intolerable difficulties in confronting reality `Theme 5:Raising the special infant into an normal one by themselves Theme 6: Being on the vigilance for their baby even though they can be relieved Theme 7:Finding out a reward for the difficulties they have experienced The results obtained in this study will enable us to comprehensively understand the experience by mothers whose baby is very low birth weight infant and furthermore to provide a new insight which helps baby.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.43.4-44
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• 2016

The presence of multiple stellar populations is now well established in most globular clusters (GCs) in the Milky Way. The origin of this phenomenon, however, is yet to be understood. In this respect, the study of NGC 2808, an intriguing GC which hosts subpopulations with extreme helium abundances, would help to resolve this problem. In order to investigate chemical abundance patterns among different subpopulations in this GC, we have performed low-resolution spectroscopy for the red-giant-branch (RGB) stars and measured CN & CH bands, and Ca line strength. We have identified at least three subpopulations from the CN abundance distribution. This GC shows CN-CH anti-correlation following the general trend among "normal" GCs. In addition, we have cross-matched our results with the high-resolution data in literature, and found a tight correlation between CN strength and sodium abundance. However, CN is anticorrelated with oxygen abundance, as expected from the well known N(&Na)-O anticorrelation. In this talk, we will discuss the implication of these results.

• Journal of the Korea Convergence Society
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• v.9 no.7
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• pp.293-300
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• 2018

To realize various opportunities to choose careers for adolescent sports players, first, it is necessary to help them choose a job suitable for each student's aptitude. In reality, adolescent sports players absolutely have insufficient time for choosing various careers unlike general adolescents and realizing them. Thus, differentiated and specialized convergence learning materials are needed by each job cluster suitable for adolescent sports players' aptitude. The learning materials, specialized for these individual job clusters are a method to show a great effect on education with investing the minimum time, so they have a high value for utilization as necessary learning information for the realization of various opportunities to choose various careers for adolescent sports players.

• Journal of The Korean Astronomical Society
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• v.53 no.3
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• pp.59-67
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• 2020

We propose semi-analytic models for the electron momentum distribution in weak shocks that accounts for both in situ acceleration and re-acceleration through diffusive shock acceleration (DSA). In the former case, a small fraction of incoming electrons is assumed to be reflected at the shock ramp and pre-accelerated to the so-called injection momentum, p_inj, above which particles can diffuse across the shock transition and participate in the DSA process. This leads to the DSA power-law distribution extending from the smallest momentum of reflected electrons, p_ref, all the way to the cutoff momentum, p_eq, constrained by radiative cooling. In the latter case, fossil electrons, specified by a power-law spectrum with a cutoff, are assumed to be re-accelerated from p_ref up to p_eq via DSA. We show that, in the in situ acceleration model, the amplitude of radio synchrotron emission depends strongly on the shock Mach number, whereas it varies rather weakly in the re-acceleration model. Considering the rather turbulent nature of shocks in the intracluster medium, such extreme dependence for the in situ acceleration might not be compatible with the relatively smooth surface brightness of observed radio relics.