• 경영과정보연구
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• 제29권3호
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• pp.51-69
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• 2010

본 연구의 목적은 우리나라 M&A시장에서 합병신고서 제출일 직전 합병당사자가 모-자회사 관계인 경우에 그 합병목적(동기)을 서베이하였고, 합병신고서 제출일 전 후 목적(동기)별로 공시효과를 실증분석하였다. 서베이 실증분석의 결과, 우리나라 모-자회사 합병의 주요한 목적(동기)으로는 효율성 증대, 경쟁력 강화 및 사업 다각화 등으로 서베이되었고, 이 중 효율성 증대가 가장 높은 비중을 차지하고 있는 것으로 조사되었다. 합병신고서 제출일 전 후 합병기업은 평균적으로 정(+)의 초과수익률을 얻는 것으로 나타났고, 합병 목적(동기)별 공시효과에서는 사업다각화의 합병 목적(동기)이 평균적으로 가장 높은 누적평균초과수익률(CAR)을 얻는 것으로 나타났다.

• 천문학논총
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• 제26권2호
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• pp.71-87
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• 2011

Gravitational waves are predicted by the Einstein's theory of General Relativity. The direct detection of gravitational waves is one of the most challenging tasks in modern science and engineering due to the 'weak' nature of gravity. Recent development of the laser interferometer technology, however, makes it possible to build a detector on Earth that is sensitive up to 100-1000 Mpc for strong sources. It implies an expected detection rate of neutron star mergers, which are one of the most important targets for ground-based detectors, ranges between a few to a few hundred per year. Therefore, we expect that the gravitational-wave observation will be routine within several years. Strongest gravitational-wave sources include tight binaries composed of compact objects, supernova explosions, gamma-ray bursts, mergers of supermassive black holes, etc. Together with the electromagnetic waves, the gravitational wave observation will allow us to explore the most exotic nature of astrophysical objects as well as the very early evolution of the universe. This review provides a comprehensive overview of the theory of gravitational waves, principles of detections, gravitational-wave detectors, astrophysical sources of gravitational waves, and future prospects.

• 천문학논총
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• 제30권2호
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• pp.463-464
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• 2015

It has been suggested that only the most luminous AGNs ($L{\gtrsim}10^{45}erg/s$) are triggered by galaxy mergers, while less luminous AGNs ($L{\sim}10^{43}erg/s$) are driven by other internal processes. The lack of merging features in low luminosity AGN host galaxies has been a primary argument against the idea of merger triggering of low luminosity AGNs. But a merger, especially a rather minor one, might still have played an important role in low luminosity AGNs, as minor merging features at low luminosities are more difficult to identify than major merging features. Using SNUCAM on the 1.5 m telescope at Maidanak observatory, we obtained deep optical images of NGC 7743, a barred spiral galaxy classified as a Seyfert 2 AGN with a low bolometric luminosity of $5{\times}10^{42}erg/s$. Surprisingly, we discovered a merging feature around the galaxy, which indicates past merging activity in the galaxy. This example indicates that the merging fraction of low luminosity AGNs may be much higher than previously thought, hinting at the importance of galaxy mergers even in low luminosity AGNs.

• 천문학회보
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• 제44권1호
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• pp.38.2-38.2
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• 2019

S0 galaxies are mostly known to be formed in dense environments from spiral progenitors. Recently, however, a new formation scenario has been suggested that field S0s can be formed from elliptical progenitors. The Sombrero galaxy (M104, NGC 4594) is a massive disk galaxy located in the field environment, and its morphological type has been controversial from Sa to E. Thus, it is an ideal target to test the new scenario. We trace the giant halo of M104 with globular clusters to test this scenario. From the wide images obtained with CFHT/MegaCam, we find a large number of globular clusters in this galaxy. We also confirm their membership by measuring the radial velocities from the spectra obtained with MMT/Hectospec. The color distribution of these globular clusters is bimodal, and blue (metal-poor) globular clusters are more spatially widely spread than red (metal-rich) globular clusters. This indicates that M104 hosts a giant metal-poor halo as well as an inner metal-rich halo. Combining this result with the fact that M104 is unusually massive and brighter than other spiral galaxies, we infer that M104 was indeed a massive elliptical galaxy that had formed a metal-rich halo by gas-rich mergers and a metal-poor halo by gas-poor mergers. In addition, we find young star clusters around the disk of M104, which shows that the disk formed after the spheroidal halos had formed. In conclusion, we suggest that M104 was originally a massive elliptical galaxy and was transformed to a lenticular galaxy by acquiring its disk later.

• 천문학회보
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• 제46권2호
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• pp.40.3-41
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• 2021

Minor mergers leave behind long lived, but extremely faint and extended tidal features including tails, streams, loops and plumes. These act as a fossil record for the host galaxy's past interactions, allowing us to infer recent accretion histories and place constraints on the properties and nature of a galaxy's dark matter halo. However, shallow imaging or small homogeneous samples of past surveys have resulted in weak observational constraints on the role of galaxy mergers and interactions in galaxy assembly. The Rubin Observatory, which is optimised to deliver fast, wide field-of-view imaging, will enable deep and unbiased observations over the 18,000 square degrees of the Legacy Survey of Space and Time (LSST), resulting in samples of potentially of millions of objects undergoing tidal interactions. Using realistic mock images produced with state-of-the-art cosmological simulations we perform a comprehensive theoretical investigation of the extended diffuse light around galaxies and galaxy groups down to low stellar mass densities. We consider the nature, frequency and visibility of tidal features and debris across a range of environments and stellar masses as well as their reliability as an indicator of galaxy accretion histories. We consider how observational biases such as projection effects, the point-spread-function and survey depth may effect the proper characterisation and measurement of tidal features, finding that LSST will be capable of recovering much of the flux found in the outskirts of L* galaxies at redshifts beyond local volume. In our simulated sample, tidal features are ubiquitous In L* galaxies and remain common even at significantly lower masses (M*>10^10 Msun). The fraction of stellar mass found in tidal features increases towards higher masses, rising to 5-10% for the most massive objects in our sample (M*~10^11.5 Msun). Such objects frequently exhibit many distinct tidal features often with complex morphologies, becoming increasingly numerous with increased depth. The interpretation and characterisation of such features can vary significantly with orientation and imaging depth. Our findings demonstrate the importance of accounting for the biases that arise from projection effects and surface-brightness limits and suggest that, even after the LSST is complete, much of the discovery space in low surface-brightness Universe will remain to be explored.

• 무역학회지
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• 제48권1호
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• pp.263-285
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• 2023

본 연구는 동남아시아와 인도네시아 시장에서 성공적인 슈퍼앱 Gojek의 비즈니스 모델, 성장과정 그리고 성공요인에 대해서 살펴보는 데 목적이 있다. Gojek의 비즈니스 모델 분석은 많은 기업들이 비즈니스 모델 수립에 활용하여 온 비즈니스 캔버스(9 Block)를 중심으로 살펴보았다. Gojek의 성장 과정은 Timeline을 기반으로 구성하였다. Gojek 1.0 단계는 차량호출 서비스를 시작하는 시기부터, Gojek 2.0은 생활밀착형 플랫폼으로 도약하는 단계, Gojek 3.0은 국내외 사업 확장과 다각화 과정, Gojek 4.0은 Tokopedia와 합병을 통한 GoTo 로 변화하며 더 높은 도약을 설정하는 단계로 살펴보았다. 이를 토대로 Gojek의 성공요인을 ① Hyperlocalization ② 퍼스트 모바일 ③ 미션 실천을 통한 사랑받는 기업 ④ 금융의 포용성 제공 ⑤ 인수합병와 파트너십을 통한 사업 확장 및 다각화⑥ 해외시장 진입 ⑦ 다양한 파트너와 투자유치 ⑧ Lock-in효과와 초 개인화로 나타내었다. 본 연구를 통해 얻은 시사점과 연구의 한계와 방향성을 논하였다.

• 천문학논총
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• 제27권4호
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• pp.287-288
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• 2012

Radio-loud active galaxies have been found to exhibit a close connection to galactic mergers and host galaxy star-formation quenching. We present preliminary results of an optical spectroscopic investigation of the AKARI NEP field. We focus on the population of radio-loud AGN and use photometric and spectroscopic information to study both their star-formation and nuclear activity components. Preliminary results show that radio-AGN are associated with early type, massive galaxies with relatively old stellar populations.

• 유통과학연구
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• 제12권7호
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• pp.45-51
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• 2014

Purpose - This study aims to explore the success of Lotte Mart in the global market, as well as examining the factors related to its entry methods. Research design, data, and methodology - This study analyzed the differences between Lotte Mart and E-mart in terms of their market entry methods, based on references and secondary data. This study is based on qualitative research that analyzes actual cases. Based on the results, this study analyzed and discussed actual cases based on references and secondary data, including newspaper interviews on Lotte Mart. Results - Lotte Mart succeeded in adapting to local markets it did this by ensuring the use of both mergers and acquisitions (M&As) and greenfield methods. In contrast, E-mart utilized only greenfield methods. Conclusions - The findings of this study may not be generalized to all industries, as only Lotte Mart was examined using the case analysis method. Therefore, the successful market entry modes of various companies should be explored in terms of FDI.

• 천문학회지
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• 제37권5호
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• pp.471-476
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• 2004

We propose an analytical model to estimate the influence of a merger on the thermal SZ effect. Following observations we distinguish between subsonic and transonic mergers. Using analytical velocity fields and the Bernoulli equation we calculate the excess pressure around a moving subcluster for an incompressible subsonic gas. Positive excess around the stagnation point and negative excess on the side of the subcluster lead to characteristic signatures in the SZ map, of the order of $10\%$ compared to the unperturbed signal. For a transonic merger we calculate the change in the thermal spectral SZ function, resulting from bow shock accelerated electrons. The merger shock compression factor determines the power law tail of the new non-thermal electron population and is directly related to a shift in the crossover frequency. This shift is typically a few percent towards higher frequencies.

• 천문학회보
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• 제40권2호
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• pp.29.2-29.2
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• 2015

Interactions such as mergers and flybys play a fundamental role in shaping galaxy morphology. We used the Horizon Run 4 cosmological N-body simulations to study the aligments of spins and shapes of interacting haloes as a function of the halo mass and large-scale density. Interactions preferentially occur in the plane of rotation, and in the direction of the major axis of prolate haloes, and the trajectories are preferentially radial and prograde. We found a very strong alignment of the shapes already at redshift as high as 4. The spins are initially unaligned or even anti-aligned, and become more and more aligned as the redshift decreases. The alignment signals are stronger and evolve more at lower densities, and mass plays a secondary role.