• Journal of the Economic Geographical Society of Korea
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• v.20 no.2
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• pp.189-213
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• 2017

This study seeks to critically examine the significance and limits of the cluster adaptive cycle model for analysis of cluster evolution and to propose research issues for future analysis of cluster evolution based on this critical examination. Until the 1980s, research on industrial complexes including clusters was based on a 'static perspective' that focuses on the aspect of economic space at a specific point in time, but the research paradigm has recently shifted to a 'dynamic perspective' focusing on 'evolution' of 'complex adaptive systems'. As a result, the adaptive cycle model has attracted attention as an analysis tool of dynamically evolving clusters. However, the cluster adaptive cycle model has emerged by being appropriately modified and expanded according to the properties of the cluster and its evolution. The cluster adaptive cycle model is a comprehensive analysis framework that identifies the characteristics of cluster evolution in terms of resource accumulation, interdependence, and resilience and classifies cluster evolution paths into six different categories. Nevertheless, there is still a need for further discussion and supplementation in terms of theoretical and empirical research to expand and deepen the model. Therefore, research issues for future analysis of cluster evolution are to specify and elaborate the cluster evolution model, to emphasize the concept of resilience, and to verify the applicability and usefulness of the model through empirical research.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.60.3-61
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• 2016

Galaxy morphology involves complex effects from both secular and non-secular evolution of galaxies. Although it is a final product of galaxy evolution, it gives a clue to the processes that the a galaxy has gone through. Galaxy clusters are the sites where the most massive galaxies are found, and thus the most dramatic merger histories are embedded. Our deep imaging program (${\mu}{\sim}28\;mag\;arcsec^{-2}$), KASI-Yonsei Deep Imaging Survey for Clusters (KYDISC), targets 14 Abell clusters at z = 0.016 - 0.14 using IMACS/Magellan telescope and MegaCam/CFHT to investigate cluster galaxies especially on low surface brightness features related to galaxy interactions. We visually classify galaxy morphology based on criteria related to secular or merger related evolution and find that the morphological mixture of galaxies varies considerably from cluster to cluster. Moreover it depends on the characteristics (e.g. cluster mass) of cluster itself which implies that environmental effects in cluster scale is also an important factor to the evolution of galaxies together with intrinsic (secular) and galaxy merger. Our deep imaging survey for morphological inspection of cluster galaxies with low surface brightness is expected to be a useful basis to understand the nature of cluster galaxies and their internal/external evolutionary path.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.35.1-35.1
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• 2016

Nearby galaxy clusters and their surrounding regions represent the current endpoint of evolution galaxy cluster evolution. We present a new catalog of 1589 galaxies, what we call Extended Virgo Cluster Catalog (EVCC), in wider area of the Virgo cluster based on the Sloan Digital Sky Survey (SDSS) Data Release 7. The EVCC covers an area 5.2 times larger than the footprint of the classical Virgo Cluster Catalog, and reaches out to 3.5 times the virial radius of the Virgo cluster. The EVCC contains fundamental information such as membership, morphology, and photometric parameters of galaxies. The EVCC defines a comprehensive galaxy sample covering a wider range in galaxy density that is significantly different from the inner region of the Virgo cluster. It will be the foundation for forthcoming galaxy evolution studies in the extended Virgo cluster region, complementing ongoing and planned Virgo cluster surveys at various wavelengths. We also present the large scale structures in the field around the Virgo cluster. We identified seven galaxy filaments and one possible sheet in three dimensions of super-galactic coordinates based on the HyperLEDA database. By examining spatial distribution and Hubble diagram of galaxies, we found that six filaments are directly associated with the main body of the Virgo cluster. On the other hand, one filament and one sheet are structures located at background of the main body of Virgo cluster. The EVCC and the filament structures will be the foundation for forthcoming studies of galaxy evolution in various environments as well as buildup of the galaxy cluster at z ~ 0, complementing ongoing and planned Virgo cluster surveys at various wavelengths.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.46.1-46.1
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• 2017

Late-type galaxies falling into a cluster would evolve being influenced by the interactions with both the cluster and the nearby cluster member galaxies. Most numerical studies, however, tend to focus on the effects of the former with little work done on those of the later. We thus perform numerical study on the evolution of a late-type galaxy falling radially toward the cluster center interacting with neighbouring early-type galaxies, using N-body, hydrodynamical simulations. Based on the information about the typical galaxy encounters obtained by using the galaxy catalog of Coma cluster, we run the simulations for the cases where a Milky Way Galaxy-like late-type galaxy, flying either edge-on or face-on, experiences six consecutive collisions with twice more massive early-type galaxies having hot gas in their halos. Our simulations show that the evolution of the late-type galaxy can be significantly affected by the high-speed multiple collisions with the early-type galaxies, such as on the cold gas content and the star formation activity, particularly through the hydrodynamic interactions between the cold disk and the hot gas halos. By comparing our simulation results with those of others, we claim that the role of the galaxy-galaxy interactions on the evolution of late-type galaxies in clusters could be comparable with that of the galaxy-cluster interactions, depending on the dynamical history.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.33.2-33.2
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• 2018

Fossil galaxy cluster has a dominant central elliptical galaxy (${\Delta}M12$ >2 in 0.5Rvir) embedded in highly relaxed X-ray halo, which indicates dynamically stable and passively evolved system. These features are expected as a final stage of the cluster evolution in the hierarchical structure formation paradigm. It is known that Abell 2261(A2261 hereafter) is classified as a fossil cluster, but has unusual features such as a high central X-ray entropy (i.e., non-cool core system), which is not expected in normal fossil clusters. We perform a kinematic study with a spectroscopic data of 589 galaxies in the A2261 field. We define cluster member galaxies using the caustic method and discover a new second bright galaxy at ~1.5 Rvir (nearly the splash-back region). It implies the current fossil state of the cluster can break in the near future. In addition, with three independent substructure finding methods, we find that A2261 has many substructures within 3 Mpc from the center of the cluster. These findings support that A2261 is not in a dynamically stable state. We argue that A2261 is in a transitional phase of dynamical evolution of the galaxy cluster and maybe previously defined fossil cluster does not mean the final stage of the evolution of galaxy clusters.

• Journal of the Korean Academic Society of Industrial Cluster
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• v.2 no.1
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• pp.1-13
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• 2008

Despite growing recognition of the significance of industrial clusters to regional economic success, there has been only limited attention paid to the effectiveness of cluster policies in old industrial regions. Many of these regions still retain functioning industrial clusters, or have clusters which are adopting new strategies as part of a process of regeneration. This paper argues that the effectiveness of cluster policies in old industrial regions depends upon the extent to which they recognise the evolutionary nature of industrial clusters. It reviews the literature on the transformation of old industrial regions in Europe, and examines how cluster policies have risen to prominence as a policy tool. These strands ate brought together in an exploration of cluster policies in old industrial regions. A brief case study is presented of the evolution of the steel industry supply chain in north east England. The conclusions focus upon the data requirements that form a starting point for informed policy intervention into presses of cluster evolution.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.56.2-56.2
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• 2010

M87, a cD galaxy in the Virgo cluster, has 3-10 times larger enclosed mass than the Milky Way at any given galactocentric radius. Thus the globular cluster (GC) system in M87 is expected to have undergone a more significant dynamical evolution than that of the Milky Way if it had started from the same initial mass function (MF) and radial distribution (RD) as the Milky Way. The evolution of MF and RD of the M87 GC system has been calculated using an advanced, realistic Fokker-Planck (FP) model that considers dynamical friction, disk/bulge shocks, and eccentric cluster orbits. We perform hundreds of FP calculations with different initial cluster conditions, and then search a wide parameter space for the best-fit initial GC MF and RD that evolves into the observed present-day GC MF and RD. We also find best-fit initial MFs and RDs for blue and red GC groups, separately.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.64.1-64.1
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• 2016

We study the evolution of a late-type galaxy (LTG) in a rich cluster environment by using N-body/SPH simulations. To do that we perform a set of simulations of a LTG falling in a Coma-like cluster and also the LTG colliding with early-type galaxies (ETGs) multiple times in the cluster environment. We use a catalog of the Coma cluster in order to estimate the typical number of collisions and the closest approach distances that a LTG would experience in the cluster. We investigate the cold gas depletion and star formation quenching of our LTG model influenced by the hot cluster gas as well as the hot halo gas of the colliding ETGs.

• Journal of The Korean Astronomical Society
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• v.46 no.4
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• pp.173-181
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• 2013

We trace the dynamical evolution of dark matter (DM) content in NGC 6397, one of the native Galactic globular clusters (GCs). The relatively strong tidal field (Galactocentric radius of ~ 6 kpc) and short relaxation timescale (~0.3 Gyr) of the cluster can cause a significant amount of DM particles to evaporate from the cluster in the Hubble time. Thus, the cluster can initially contain a non-negligible amount of DM. Using the most advanced Fokker-Planck (FP) method, we calculate the dynamical evolution of GCs for numerous initial conditions to determine the maximum initial DM content in NGC 6397 that matches the present-day brightness and velocity dispersion profiles of the cluster. We find that the maximum allowed initial DM mass is slightly less than the initial stellar mass in the cluster. Our findings imply that NGC 6397 did not initially contain a significant amount of DM, and is similar to that of NGC 2419, the remotest and the most massive Galactic GC.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.46.2-46.2
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• 2014

Galaxy morphology is involved complex effects of both secular and non-secular evolution of galaxies. Although it is a final product of a galaxy evolution, it may give a clue for the process that the galaxy suffer. Galaxy clusters are the sites where the most massive galaxies are found, and the most dramatic merger histories are embedded. Morphology study in nearby universe, e.g. Virgo cluster, is well established, but for clusters at z ~ 0.1 it is only focused on bright galaxies due to observational limits. Our optical deep imaging of 14 Abell clusters at z = 0.014 - 0.16 using IMACS f/2 on a Magellan Badde 6.5-m telescope and MegaCam on a 3.8-m CFHT enable to classify detailed morphology. For the galaxies in our data, we investigated their morphology with several criteria related to secular or merger related evolution. Our research on detailed morphology of thousands of galaxies through deep imaging would give a general census of cluster galaxies and help to estimate the evolution of cluster galaxies.