• International Journal of Computer Science & Network Security
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• v.22 no.12
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• pp.212-216
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• 2022

Space based constellation network is a kind of ad hoc network in which users are self-organized without center node. In space based constellation network, users are allowed to enter or leave the network at any given time. Thus, the number of active users is an unknown and time-varying parameter, and the performance of the network depends on how accurately this parameter is estimated. The so-called problem of active user identification, which consists of determining the number and identities of users transmitting in space based constellation network is discussed and a novel active user identification method is proposed in this paper. Active user identification code generated by transmitter address code and receiver address code is used to spread spectrum. Subspace-based method is used to process received signal and judgment model is established to identify active users according to the processing results. The proposed method is simulated under AWGN channel, Rician channel and Rayleigh channel respectively. Numerical results indicate that the proposed method obtains at least 1.16dB E_b/N₀ gains compared with reference methods when miss alarm rate reaches 10^-3.

• Journal of Communications and Networks
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• v.11 no.3
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• pp.287-296
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• 2009

Although asymptotic bounds of wireless network capacity have been heavily pursued, the answers to the following questions are still critical for network planning, protocol and architecture design: Given a three-dimensional (3D) network space with the number of active users randomly located in the space and using the wireless communication technology, what are the expected per-flow throughput, network capacity, and network transport capacity? In addition, how can the protocol parameters be tuned to enhance network performance? In this paper, we focus on the ultra wideband (UWB) based wireless personal area networks (WPANs) and provide answers to these questions, considering the salient features of UWB communications, i.e., low transmission/interference power level, accurate ranging capability, etc. Specifically, we demonstrate how to explore the spatial multiplexing gain of UWB networks by allowing appropriate concurrent transmissions. Given 3D space and the number of active users, we derive the expected number of concurrent transmissions, network capacity and transport capacity of the UWB network. The results reveal the main factors affecting network (transport) capacity, and how to determine the best protocol parameters, e.g., exclusive region size, in order to maximize the capacity. Extensive simulation results are given to validate the analytical results.

• Korean Institute of Interior Design Journal
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• v.16 no.3 s.62
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• pp.58-65
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• 2007

The residential space of super high-rise buildings, having a form of a huge three-dimensional vertical city, affect the residents psychologically and qualitatively according to the line of flow. Because of these affects, the system of the line of flows is a very important factor. In this study, we recognize the super high-rise apartment's line of flow as a semantic network system based on case studies. And we also understand the mutual relationship by analyzing each space to recognize what effect it does on the residential environment. Furthermore, to bring up a better semantic network system for super high-rise apartment's line of flows is our goal. According to the case studies, the semantic network of the line of flow consists of 3 parts: the functional network, economical network and unit network. The functional network is composed of the 'need' and 'has', while the economical network includes variable walls that can be changed following the user's taste and eccentric positioned living rooms that protect personal privacy. Therefore the economical network started to appear while the personal value changed according to the improvement of the social condition. Finally, the unit network is a network that effects each unit that has ambiguous boundaries due to the appropriate arrangement between transitional spaces. And the unit network is based on the functional network.

• Journal of Forest and Environmental Science
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• v.32 no.1
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• pp.1-9
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• 2016

Accessibility of urban green space, as an important index of evaluating the service level of urban green space, not only shows the resident's access to green space, but also reflects the environment quality of urban living. Since the quantity, area and space distribution of the patches in urban green space directly affect the function of urban green space and the quality of urban environment, the research on the accessibility of urban green space holds great significance to improve the service of urban green space and the living environment quality. Based on GIS software, this research uses the road network and the population distribution data of Nanjing's city proper to conduct quantitative analysis of the accessibility of park green space and the convenience for residents to travel under different forms of transportation. After the case analysis, the author tests the application of road network in studying the accessibility of urban park green space and proposes a GIS-based method to study the accessibility and the rational layout of urban green space.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.77.2-77.2
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• 2021

Starting with the observation of sunspots in 1987, Korea Astronomy and Space Science Institute (KASI) has developed and installed various ground-based instruments for space weather research in Korea. Recently, SNIPE and CODEX are also being developed as space-based instruments. Expansion of the observation area and simultaneous observation have become important in the study of space weather. We have started Next-Generation Space Weather Observation Network Project this year. In order to establish a solar observation network, we planned to develop the Next Solar Telescope (NxST) which is a solar imaging spectrograph, and to install three NxST in the northern hemisphere. And we also planned to develop the Thermosphere-Ionosphere-Mesosphere Observation System (TIMOS), Global Navigation Satellite System (GNSS), and Geomagnetic packages, and install them in about ten sites over the world, for the purpose of establishing a global observation network for the near-earth space weather. We can take simultaneously observed space weather data in the global area, and are expecting it will play an important role in the international community for space weather research. We also have a strategy to secure observational technologies necessary for big space missions in the future, through this project.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.241-241
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• 2012

MOGABA is a project monitoring of gamma-ray bright AGN(Active Galactic Nuclei). Since May 2011, we have observed total flux, degree of linear polarization, and polarization angle of about twenty AGN once a week at 22, 43 and 86GHz using KVN(Korean VLBI Network) 21m radio telescopes. We have observed variation of total flux of BLLAC and OJ287 from May 2011 to March 2012. We have observed flares of total flux at 22GHz for those sources from October 2011 to November 2011. In this paper we report the variation of total flux, degree of linear polarization and polarization angle at 22, 43, 86GHz for BLLAC and OJ287.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.239.2-239.2
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• 2012

We report preliminary results of MOGABA project for monitoring total flux density, linearly polarized flux, and polarization angle at 22, 43 and 86GHz of Gamma-ray bright AGN (Active Galactic Nuclei) with KVN (Korean VLBI Network) 21-m radio telescopes. The project has been conducted in one year since May 2011 with an effective monitoring cycle of 1 week, observing four main objects (3C 454.3, BL Lac, 3C 273, and 3C 279). More objects were included in the source list when they had flared in Gamma-ray. Especially, we included a compact radio source at the Galactic center, SgrA* since Jan. 2012. In this paper, we report the current status of the project and preliminary results for the monitoring observations.

• Journal of the Korean Institute of Landscape Architecture
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• v.37 no.5
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• pp.53-63
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• 2009

This study aims at presenting a plan to build an open space network system in the city of Daejeon, assuming that parks and the green space system as a broad concept are to make a network by connecting open spaces such as parks, green spaces, squares, pedestrian roads, historical spots, etc. In the case of old downtown in Daejeon, this study examined the possibility of applying an open space network in the city of Daejeon and categorize them according to the findings from examining the case area, which enables to make a plan for building an open space network system in Daejeon. As a result, public offices and business buildings as an active open space have public open spaces in front of buildings and these front public open spaces are connected to pedestrian roads(gray open space). Since these pedestrian roads are consequently connected to large parks and rivers(green or blue open space), this overall spatial sequence can form an open space system. In addition, parks and green spaces, which have been fundamental elements so far, exist in relatively small and scattered areas at the center of the city. Hence, more parks and green space are needed to improve a park and green space system. However, it is very difficult to create new parks and green spaces in downtown, especially in old downtown areas. Therefore making an open space network system which spreads out over the whole city will form a healthy open space network in the downtown area.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.258-260
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• 2006

In this paper, we designed a embedded system that will perform a primary role of Tangible Space implementation. This hardware includes function of image capture through camera interface, image process and sending off image information by LAN (local area network) or WLAN(wireless local area network). We define this hardware as a network based Visual Agent Platform for Tangible Space

• Bulletin of the Korean Space Science Society
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• 2009.04a
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• pp.56.2-56.2
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• 2009