Earticle

기업결합 시뮬레이션 모형은 과점 시장에서 가격과 산출량의 결정에 대한 구조적(structural) 분석을 함으로써 기업결합 시 관련 기업의 상품가격 변화와 그에 따른 후생의 변화를 직접적으로 계산할 수 있도록 한다. 기존의 기업결합 시뮬레이션 모형은 일면시장(one-sided market)에서 판매자의 가격변화에 따른 수요변화, 즉 수요탄력성에 기반하여 개발되었다. 본 논문에서는 양면시장의 특성을 지닌 인터넷 쇼핑몰 시장에서의 기업결합의 경쟁효과 평가에 활용될 수 있는 이론적 모형을 도출한다.

Merger simulation models evaluate unilateral merger effects by predicting welfare and price changes. Previous models are developed to analyze merger effects in one-sided market. In this paper, we develop a merger simulation model to analyze the unilateral effects in a two-sided market. We apply the tool to evaluate the merger effect between two Internet shopping malls.

We present our study on a comparison of dark matter halo merger history from the runs using different numerical simulation codes. To analyze the uncertainty caused by the use of different N-body calculation methods, we compare the results from two cosmological hydrodynamic simulation codes GADGET-2 and RAMSES, which use a TreePM algorithm and the Adaptive Mesh Refinement(AMR) technique respectively. We perform cosmological dark matter-only simulations with the same parameter set and initial condition for both. The dark matter halo mass functions from two simulation runs correspond well with each other, except for lower mass haloes. The discrepancy on the low-mass haloes in turn causes a notable difference in halo merger rate, especially for the case of extremely minor merger. The result from GADGET-2 predicts that most haloes undergo more number of mergers with small haloes than that from RAMSES, independent of halo mass and environment. However, in the context of the study on galaxy evolution, such extreme minor mergers generally do not have strong effects on galaxy properties such as morphology or star formation history. Hence, we suggest that this uncertainty could be quantitatively negligible, and the results from two simulations are reliable even with only minor difference in merger history.

Abell 115 is a renowned cluster merger at z=0.197. It exhibits an asymmetric X-ray distribution with cometary tails and a megaparsec-sized radio relic stretching in the northeastern direction from the core of the northern cluster. Many observations have concluded that this cluster merger has a large impact parameter, but there has been no numerical analysis on the structure of Abell 115. In this study, we simulate Abell 115 with Gadget2 N-body/SPH code to reproduce the X-ray and weak lensing features of Abell 115. We find a new plausible merger scenario of Abell 115, wherein the northern cluster is currently in an outgoing phase. The predicted X-ray emission has a similar morphology to the observed tail of the northern cluster. However, in order to reproduce the observed line-of-sight velocity and projected distance while maintaining the two systems gravitationally bound, the system should possess a large projection angle, which makes the shock look considerably more diffused than the observed radio relic.