• Publications of The Korean Astronomical Society
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• v.20 no.1 s.24
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• pp.85-95
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• 2005

We collected eleven large astronomical catalogues, which include 2MASS, USNO B1.0, GSC 2 catalogues and so on. Most of these catalogues are the frequently used by astronomers for all sorts of applications. But the researches are faced with the problem of accessing these databases because these catalogues contain from tens millions up to thousands of millions of records. So we developed a web application system to manage these large catalogues, the main purpose of the web application is to allow a powerful and efficient querying activity on these catalogues through internet by using a simple web interface. User could retrieve the query result in variety of formats including plain text, HTML, Microsoft Excel format (XLS), and VOTable. Furthermore, user also could display and analyze result graphically by using a powerful interactive visualization tools named VOPlot which was developed by the Virtual Observatory-India (VOI) project.

• Korean Institute of Interior Design Journal
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• v.18 no.6
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• pp.158-165
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• 2009

Ever since the industrial revolution, large cities have become a field of new lifestyle and urbanization, causing climate change and environmental pollution. As a result, countermeasures for revolving these problems is needed. In addition, large cities in the information age have become a space where each nation executes its public policy to express the competitiveness of each city. In this study, countermeasures for the environmental crises caused by urbanization as well as the sustainable spatial designs for the cities are investigated as a new source of urban competitiveness, and the environmental aesthetics for designing public space is considered. The purpose of this study is to suggest a direction for sustainable designs and planning that is applicable to public space. According to the definition of sustainability, the items of the spatial implementation of ecological, economical and social sustainability are categorized. Based on this categorization, the sustainable designs of public space are classified into five types, and a comprehensive analysis of good public spaces from previous literature is conducted. The concepts of design and three elements--public space, sustainability, and their instrumental meanings, are integrated in this study. The significance of this study lies in the actual application of the classification to the planning and design of sustainable public space in cities, rather than being a conceptual classification.

• Journal of the Korean Institute of Educational Facilities
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• v.26 no.5
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• pp.25-36
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• 2019

School gymnasium is a multi-purpose large space building for various events and physical education activities, and is a facility that requires an approach to the desirable structural design, besides mechanical problems of structure against loads. For the integrated structure design concerning the architectural features, the major considerations of gymnasium planning that are the internal and external shape of the gymnasium, the space scale with structure members, the structural efficiency by members weight reduction and openness of the gymnasium space will have to take into account in the structural planning. From this point of view, the several cases of the school gymnasium were investigated and the parametric analyses were performed to the models using the various structural system. The parameters were the composition elements of structure system that are profile of structure, rigidity of member, connection and anchorage and stability. At the result, It was presented that the profile of structure member was the most influential factor to structural efficiency and the effect of the form and space of gymnasium. Also the design informations of structure design having the various feature of form and space were presented for the initial gymnasium planning.

• Journal of Information Processing Systems
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• v.18 no.3
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• pp.374-388
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• 2022

Database systems usually have many parameters that must be configured by database administrators and users. RocksDB achieves fast data writing performance using a log-structured merged tree. This database has many parameters associated with write and space amplifications. Write amplification degrades the database performance, and space amplification leads to an increased storage space owing to the storage of unwanted data. Previously, it was proven that significant performance improvements can be achieved by tuning the database parameters. However, tuning the multiple parameters of a database is a laborious task owing to the large number of potential configuration combinations. To address this problem, we selected the important parameters that affect the performance of RocksDB using random forest. We then analyzed the effects of the selected parameters on write and space amplifications using analysis of variance. We used a genetic algorithm to obtain optimized values of the major parameters. The experimental results indicate an insignificant reduction (-5.64%) in the execution time when using these optimized values; however, write amplification, space amplification, and data processing rates improved considerably by 20.65%, 54.50%, and 89.68%, respectively, as compared to the performance when using the default settings.

• Proceedings of the Korea Society of Design Studies Conference
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• 2002.05b
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• pp.32-33
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• 2002

• The Bulletin of The Korean Astronomical Society
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• v.28 no.2
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• pp.51-51
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• 2003

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.47.2-47.2
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• 2015

We present a large scale structure consisting of eight galaxy filaments around the Virgo cluster in the window of -20 Mpc < SGX, SGZ < 20 Mpc, and 4 Mpc < SGY < 32 Mpc using the HyperLEDA database. While six of the filaments were reported in previous studies, two filaments are newly found in this study. We exploited a large number of faint ($M_B$ < -10) galaxies in comparison with previous studies, which facilitates defining filaments more clearly. The previously known filaments are all in SGY < 16 Mpc and appear to distribute in association with the Virgo cluster in galaxy distribution. Moreover, peculiar velocities of galaxies in these filaments show a distinct offset from the Hubble flow indicating their infall motion toward the Virgo cluster. All of these results confirm that these filamentary structures are under the gravitational influence of the Virgo cluster. Both of the newly discovered filaments are located beyond the 'zero-velocity surface' of the Virgo cluster. One of them is associated in the NGC5353/4 group and the other one appears to penetrates the W and M group of the Virgo cluster. The filamentary structure around the Virgo cluster consisting mainly of the dwarf galaxies allows us to achieve a better understanding of large scale structure and its influence on the build-up of the galaxy cluster at z~0.

• Tunnel and Underground Space
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• v.28 no.4
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• pp.304-324
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• 2018

Singapore government is strongly promoting the development and utilization of underground space in national level due to the nature of the city state which lacks the land. As well as conventional underground utilization in shallow depth such as metro and underground roads, large rock cavern utilization has been started after the successful completion of the underground ammunition depot in the rock, and Jurong Rock Cavern, the second large underground cavern project has just been completed. In this paper, after evaluating the conditions of the underground development in rock mass through the analysis of the geology of Singapore, the history and current status of underground development are examined. Several creative development plans from Singapore government such as underground reservoirs, underground automation logistics systems and underground warehouses storage etc. are introduced with technical issues. This paper also discusses the problems and issues related to the development of large underground space in rock mass in Singapore. It is expected that such active development of underground space in Singapore can give many opportunities and also challenges for rock engineering and industry in the future.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.8
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• pp.4006-4020
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• 2018

In recent years, one of the most remarkable 5G technologies is massive multiple-input and multiple-output (MIMO) system which increases spectral efficiency by deploying a large number of transmit-antennas (eg. tens or hundreds transmit-antennas) at base station (BS). However, conventional massive MIMO system using single-polarized (SP) transmit-antennas increases the size of the transmit-array proportionally as the number of transmit-antennas increases. Hence, size reduction of large-scale transmit-array is one of the major concerns of massive MIMO system. To reduce the size of the transmit-array at BS, dual-polarized (DP) transmit-antenna can be the solution to halve the size of the transmit-array since one collocated DP transmit-antenna deploys vertical and horizontal transmit-antennas compared to SP transmit-antennas. Moreover, proposed DP massive MIMO system increases the spectral efficiency by not only in the space domain but also in the polarization domain whereas the conventional SP massive MIMO system increases the spectral efficiency by space domain only. In this paper, the comparative performance of DP and SP massive MIMO systems is analyzed by space division multiple access (SDMA) and space-polarization division multiple access (SPDMA) respectively. To analyze the performance of DP and SP massive MIMO systems, DP and SP spatial channel models (SCMs) are proposed which consider depolarized propagation channels between transmitter and receiver. The simulation results show that the performance of proposed 32 transmitter (Tx) DP massive MIMO system improves the spectral efficiency by about 91% for a large number of user equipments (UEs) compare to 32Tx SP massive MIMO system for identical size of the transmit-array.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.53.3-54
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• 2015

We are developing large arrays of X-ray microcalorimeters for applications in X-ray astronomy. X-ray microcalorimeters can detect the energy of X-rays with extremely high resolution. High-resolution Imaging spectroscopy enabled by these arrays will allow us to study the hot and energetic nature of the Universe through the detection of X-rays from astronomical objects such as neutron stars or black holes. I will introduce the state-of-the-art X-ray microcalorimeters being developed at NASA/GSFC and the future X-ray observatory missions based on microcalorimeters.