• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.46.3-46.3
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• 2017

We investigate the changes of galaxy spin orientation in dense environments using hydrodynamical cosmological zoom-in simulations for 17 galaxy clusters. This study reveals that the spin axes of satellite galaxies become more unstable when the satellites have lower initial $V/{\sigma}$, orbits with smaller pericenter distance, and higher merger rates after infall into the model clusters. The satellite galaxies involved in mergers after infall experience twice larger angular changes of spin axes than those without mergers. We also find that perturbation exerted by environments or neighboring galaxies strongly correlates with the stability of spin orientation and final $V/{\sigma}$. On the other hand, the size or stellar mass density of the satellites are not significantly affected by mergers or perturbation in cluster environments.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.52.1-52.1
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• 2017

The discovery of GW150914, black hole - black hole merger via gravitational waves (GWs) opened a new window to observe the Universe. GW frequencies from heavenly bodies and early Universe are expected to span between sub-nHz up to kHz. At present, GW detectors on Earth (LIGO, Virgo, KAGRA, LIGO-India) aims frequency ranges between 10-2000 Hz. The space-borne GW detector and Pulsar Timing Array targets mHz and nHz sources. Starting in March 2017, the KKN (KASI-KISTI-NIMS) collaboration launched a pilot study of SLGT (Superconducting Low-frequency Gravitational-wave Telescope). This project is funded by NST (Korea Institute of Science and Technology). The main detection bands expected for SLGT ranges between 0.1-10Hz, which is complementary of LIGO-type detectors and LISA for multi-band GW observation. We will present an overview of the SLGT project and report the status of the NST pilot study. We will also present prospective of GW astronomy with SLGT.

• Journal of the Korean Society of Costume
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• v.53 no.4
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• pp.17-29
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• 2003

Long Sleeve Costume is often seen not only in ancient China but also in various neighboring places throughout the time. Costumes show the societies cultural preferences and values at that time, and Long Sleeve Costume is no exception. In my research, 1 focused on the time period from Han Dynasty to Tang dynasty in ancient China. During Han dynasty, Shenyl style robe(심의형 포) was widely worn, and it shows very little foreign cultural influence. For the period of Wei·Jin Southern and Northern Dynasties, foreign aspects of costume started to show up Possibly due to the influence of Buddhism and influx of foreign tribes. For instance, it is not too difficult to find hufu (호복) as well as Shenyl style robe, and it appears this Wei Jin Southern and Northern Dynasties may have been a transitional period of accommodating two cultures without complete merger. Now, when it comes to Tang dynasty, we observe a creation of new cultural form in costume after adopting exotic culture. Because Sh ny style robe. often observed for a long time in Chinese history, disappeared, and tuanling(단영) and fanling(번영) became the main stream in their costume style in Tang dynasty.

• Journal of The Korean Astronomical Society
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• v.49 no.4
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• pp.145-155
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• 2016

The Sausage radio relic is the arc-like radio structure in the cluster CIZA J2242.8+5301, whose observed properties can be best understood by synchrotron emission from relativistic electrons accelerated at a merger-driven shock. However, there remain a few puzzles that cannot be explained by the shock acceleration model with only in-situ injection. In particular, the Mach number inferred from the observed radio spectral index, M_radio ≈ 4.6, while the Mach number estimated from X-ray observations, M_X−ray ≈ 2.7. In an attempt to resolve such a discrepancy, here we consider the re-acceleration model in which a shock of M_s ≈ 3 sweeps through the intracluster gas with a pre-existing population of relativistic electrons. We find that observed brightness profiles at multi frequencies provide strong constraints on the spectral shape of pre-existing electrons. The models with a power-law momentum spectrum with the slope, s ≈ 4.1, and the cutoff Lorentz factor, γ_e,c ≈ 3−5×10⁴, can reproduce reasonably well the observed spatial profiles of radio fluxes and integrated radio spectrum of the Sausage relic. The possible origins of such relativistic electrons in the intracluster medium remain to be investigated further.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.9
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• pp.241-249
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• 2020

This study aims to empirically examine the effect of foreign direct investment (FDI) and corruption on the development of public-service sectors in 10 ASEAN countries. It then investigates whether this relationship is different between two FDI compositions including greenfield FDI and FDI in the form of cross-border merger and acquisitions (M&As). Using a panel database of 10 ASEAN countries during the period 1996-2015 from various sources including the World Development Indicators of the World Bank and UNCTAD, we first find that FDI strongly and positively contributes to the development of the public-service sectors in the recipient nations, except for the electricity sector. However, we show that this relationship is dependent on the type of FDI modes of entry. Specifically, while greenfield investment exerts a beneficial influence on the development of telecommunication and transportation sectors, cross-border M&A has no effect on these sectors, perhaps because of the distinct differences among three public service sectors. Finally, we found that in a highly corrupt environment, aggregate FDI might have no influence on all three public-service sectors, possibly because the two contradictory influences of the interaction terms between corruption and two FDI sub-types seem to cancel each other out.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.4
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• pp.422-427
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• 2003

The purpose of this study analyzes the effects of M＆A between conglomerate and non-conglomerate corporational with 57 samples of firms during the period from 1990 to 1997 right before IMF. financial crisis. These models employed to measure effects of M＆A in this paper are both market model and market adjusted return model using test of t-statistics. Results of this article show that negative excess returns are observed for non-conglomerate mergers and positive excess gains are exhibited for conglomerate mergers. This implies that conglomerate mergers are more effective than firm specialization in terms of merger effects.

• Korean Management Science Review
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• v.26 no.3
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• pp.23-35
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• 2009

This study deals with the location management in WCDMA (Wideband Code Division Multiple Access) networks. The new location management method is the one of the many techniques used to provide the packet switched (PS) services effectively in WCDMA networks. WCDMA introduces RA (routing area) for the PS services in addition to LA (location area) for the circuit switched (CS) services. WCDMA system also adopts the cooperative paging and the combined area update which are to decrease signaling traffic using the PS network resources for the CS services. Considering the characteristics of the WCDMA networks, this study formulate into the mathematical programming problem for the location management. Rather than the existing researches which consider the single MSC/SGSN networks, we deal with the multi MSC/SGSN networks, where both MSC area and SGSN area should be determined as well. Fairness between traffic loads of MSC/SGSN and the system cost incurred to MSC/SGSN are also incorporated into our model, which make the model more realistic. We propose greedy algorithms for the problems, which consists of the merger of two neighboring areas and the movement of an area. Extensive experiment has been done based on the realistic problem examples. Followed by the analysis of parameter effect on the final solutions and the quality of final solutions obtained by our greedy algorithms. Our proposed model and analysis result can be used to determine WCDMA system areas and to predict the system performance measures by the determination.

• Speech Sciences
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• v.13 no.4
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• pp.69-87
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• 2006

This study aims to describe the vowel system of present-day American English and to discuss some of its phonetic variations due to regional differences. Fifteen speakers of American English from various regions of the United States produced the monophthongs of English. The vowel duration and the frequencies of the first and the second formant were measured. The results indicate that the distinction between the vowels [c] and [a] has been merged in most parts of the U.S. except in some speakers from eastern and southeastern parts of the U.S., resulting in the general loss of phonemic distinction between the vowels. The phonemic merger of the two vowels can be interpreted as the result of the relatively small functional load of the [c]-[a] contrast, and the smaller back vowel space in comparison to the front vowel space. The study also shows that the F2 frequencies of the high back vowel [u] were extremely high in most of the speakers from the eastern region of the U.S., resulting in the overall reduction of their acoustic space for high vowels. From the viewpoint of the Adaptive Dispersion Theory proposed by Liljencrants & Lindblom (1972) and Lindblom (1986), the high back vowel [u] appeared to have been fronted in order to satisfy the economy of articulatory gesture to some extent without blurring any contrast between [i] and [u] in the high vowel region.

• Journal of The Korean Astronomical Society
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• v.50 no.4
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• pp.93-103
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• 2017

We explore the shock acceleration model for giant radio relics, in which relativistic electrons are accelerated via diffusive shock acceleration (DSA) by merger-driven shocks in the outskirts of galaxy clusters. In addition to DSA, turbulent acceleration by compressive MHD modes downstream of the shock are included as well as energy losses of postshock electrons due to Coulomb scattering, synchrotron emission, and inverse Compton scattering off the cosmic background radiation. Considering that only a small fraction of merging clusters host radio relics, we favor a reacceleration scenario in which radio relics are generated preferentially by shocks encountering the regions containing low-energy (${\gamma}_e{\leq}300$) cosmic ray electrons (CRe). We perform time-dependent DSA simulations of spherically expanding shocks with physical parameters relevant for the Sausage radio relic, and calculate the radio synchrotron emission from the accelerated CRe. We find that significant level of postshock turbulent acceleration is required in order to reproduce broad profiles of the observed radio flux densities of the Sausage relic. Moreover, the spectral curvature in the observed integrated radio spectrum can be explained, if the putative shock should have swept up and exited out of the preshock region of fossil CRe about 10 Myr ago.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.4
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• pp.168-176
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• 2014

The enterprise life cycle derived from the product life cycle consists of introduction, growth, maturity and decline. The enterprise tries to reach the growth stage early and stay at the maturity stage stably through expanding its businesses and investing for the new technology. The public enterprise is not different but its life cycle is more prone to be affected by the national development and policy. A typical example can be found in the case of the quasi market SOC public enterprise which spends massive amount of fund to provide social infrastructure. After the fulfillment of its mandated mission it is exposed to the pressure of a merger or a closure usually because large portion of the debt is directly linked to the national financial stability and credit ratings. This research is focused on the variables that influence the life cycle of the quasi market SOC public Enterprise for its future competitiveness is in connection with its normalization, advancement and rationalization. In this respect, categorical variables system centering on public characteristics and profitability drew eight categorical variables such as policy outcomes, public benefit, finance and business values etc.