• Journal of Communications and Networks
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• v.8 no.4
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• pp.369-377
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• 2006

Recently, the metropolitan area network (MAN) has attracted much attention in telecommunication research and has emerged as one of the most important research topics in the community. Several standards representing the first step for developing metropolitan networks have been published; IEEE 802.16 (WiMAX) has taken a relevant role in reaching the goal of realizing a full-service network all over a urban and suburban area. At the same time, the wireless local area networks (WLAN) have been widely used for in-home or short range communications, mainly basing on the IEEE 802.11 (WiFi) standard. A consequence is the increasing interest in interworking technology, that allows an interconnection between different standards by maintaining certain properties, mainly in terms of quality of service (QoS). One of the major issues is to design bridging devices capable of transparently interconnect different wireless technologies. In this paper, we propose two interconnection bridging solutions between WiMAX and WiFi links; the first is more based on the concept of maintaining a certain end-to-end QoS level independently from the wireless technologies used. The second method is more devoted to the reduction of the implementation complexity at the cost of no QoS assurance. The performance of the two methods are compared by resorting to computer simulations showing the advantages of each one technique.

• Journal of Environmental Science International
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• v.25 no.5
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• pp.673-681
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• 2016

The adequacy of urban air quality monitoring networks in the largest metropolitan city, Seoul was evaluated using multivariate analysis for $SO_2$, $NO_2$, CO, PM10, and $O_3$. Through cluster analysis for 5 air pollutants concentrations, existing monitoring stations are seen to be clustered mostly by geographical locations of the eight zones in Seoul. And the stations included in the same cluster are redundantly monitoring air pollutants exhibiting similar atmospheric behavior, thus it can be seen that they are being operated inefficiently. Because monitoring stations groups representing redudancy were different depending on measurement items and several pollutants are being measured at the same time in each air monitoring station, it is seemed to be not easy to integrate or transmigrate stations. But it may be proposed as follows : the redundant stations can be integrated or transmigrated based on ozone of which measures are increasing in recent years and alternatively the remaining pollutants other than the pollutant exhibiting similar atmospheric behavior with nearby station's can be measured. So it is considered to be able to operate air quality monitoring networks effectively and economically in order to improve air quality.

• International Journal of Advanced Culture Technology
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• v.6 no.3
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• pp.37-43
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• 2018

This paper measures and maps multi-dimensional residential segregation of immigrants in Seoul metropolitan area at city/county/district level as well as town level, thereby adding to our understanding of the urban structure and its spatial distribution impacted by immigration. The perspective offered here focuses on the segregation spurred by transnational migrants and their urban settlement. By drawing population data for 79 city/county/district administrative units from the Korea Immigration Service, residential segregation of immigrants in Seoul metropolitan area is measured based on Massey & Denton's four segregation indices: evenness, exposure, concentration and clustering. The empirical findings suggest that Seoul metropolitan area is highly segregated and the areas showing hyper-segregation appear in Seoul city and Gyeonggi province. As immigrants are foreseen to continue to increase in the future, this research contributes both empirically and theoretically to preliminary research on spatial segregation of immigrants by showing how ethnic places are segregated spatially through ethnic networks that support the geographic concentration of minority groups.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.559-569
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• 2016

This study examined flow between regions based on the spatial structure of the territory and characterized the flow patterns by analyzing regional networks via transportation connectivity. To accomplish this, transportation connectivity of the entire nation was examined using 2010 national express bus OD data from the Korea Transport Database. After the initial analysis, 2010 car OD data describing networks in seven regions (125 cities and districts), Gangwon-do, Gyeongsangnam-do, Gyeongsangbuk-do, Jeollanam-do, Jeollabuk-do, Chungcheong-do and Seoul, were analyzed to identify transportation connectivity. The results revealed that Korea has strong triangular-belt-shaped transportation connectivity that connects among metropolitan areas in the Jeolla and Gyeongsang areas. Particular zones are set by regional characteristics and functional connectivity for each zone. The results of this study will be useful as a basic material to establish development strategies and customized regional policy development, as well as balanced development.

• Journal of the Korean Geographical Society
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• v.43 no.4
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• pp.544-560
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• 2008

This study seeks to clarify the background and factors for the expansion of bus networks that connect Incheon International Airport with its hinterlands. For this research objective, this paper analyzes the relationships among the change of bus routes, competitive transportation modes, passenger fares, and the shortest time distance. Previously, the hinterlands of route bus networks that connect Gimpo International Airport were Seoul metropolitan area, Chungcheong region, Jeonju and Iksan in Jeollabuk-do(province). However, the opening of Incheon International Airport resulted in the expansion of the hinterlands of bus networks to Gangwon-do, Gwangju, and major cities in Youngnam region. Simultaneously, route bus networks also expanded in Seoul metropolitan area. Each bus route connecting Incheon International Airport with its hinterlands was opened by a single bus company or various bus companies. In many cases, due to the uncertainty of revenues or bus company's regional ties, a bus route was opened by various bus companies. In this paper, the analysis of the number of one-way route bus service and density of flight passengers shows that the frequency of the route bus service for Seoul except Gangseo-gu(ward) and for Seoul's satellite cities(Suwon, Seongnam, Anyang, Gunpo, Guri, and Osan) should be decreased. The analysis also shows that the frequency of the route bus services for the other cities, counties(Guns), and wards(gus) should be increased. In Seoul metropolitan area, although route bus fares are more expensive than subway fares, passengers use route bus more frequency than subway because time distance of route bus is shorter than that of subway and subway transfer is inconvenient. In general, outside Seoul metropolitan area, air flight is preferred in the regions that have airports. In contrast, the route bus is preferred in Daegu and other regions that do not have airports.

• Atmosphere
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• v.29 no.2
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• pp.183-196
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• 2019

High-quality and high-resolution meteorological information is essential to reduce damages due to disastrous weather phenomena such as flash flood, strong wind, and heat/cold waves. There are many meteorological observation stations operated by Korea Meteorological Administration (KMA) in Seoul Metropolitan Area (SMA). Nonetheless, they are still not enough to represent small-scale weather phenomena like convective storm cells due to its poor resolution, especially over urban areas with high-rise buildings and complex land use. In this study, feasibilities to use additional pre-existing networks (e.g., operated by local government and private company) are tested by investigating the effects of network density on the gridded horizontal distribution of two meteorological variables (temperature and precipitation). Two heat wave event days and two precipitation events are chosen, respectively. And the automatic weather station (AWS) networks operated by KMA, local-government, and SKTechX in Incheon area are used. It is found that as network density increases, correlation coefficients between the interpolated values with a horizontal resolution of 350 m and observed data also become large. The range of correlation coefficients with respect to the network density shows large in nighttime rather than in daytime for temperature. While, the range does not depend on the time of day, but on the precipitation type and horizontal distribution of convection cells. This study suggests that temperature and precipitation sensors should be added at points with large horizontal inhomogeneity of land use or topography to represent the horizontal features with a resolution higher than 350 m.

• Journal of Internet Computing and Services
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• v.4 no.6
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• pp.69-73
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• 2003

ATM and Ethernet are desirable transport mechanisms for the realization MAN(Metropolitan Area Networks). A relatively small sized switching system for MAN based on ATM is proposed and its performance is evaluated in this paper. For the performance evaluation, traffics should be firstly modeled because they are highly bursty. By varing the ratio of VBR traffics, detrimental effect of VBR traffics may be observed. Traffic load at each input port is also varied, From the results of simulation, operation conditions of the system to meet required QoS are obtained.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09b
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• pp.1110-1111
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• 2005

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.6
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• pp.67-81
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• 2011

In recently years, there are cyber-weapon aim to national infrastructure such as 'stuxnet'. Security experts of the world are paying attention to this phenomenon. The networks which controls traffic, subway, waterworks of the city are safe from threats such as computer virus, malware, because the networks were built on closed-networks. However, it's about time to develop countermeasure for the cyber-weapon. In this paper, we review status-quo of the control systems for metropolitan infrastructure and analyze the risk of industrial control system in SCADA(Supervisory Control And Data Acquisition) network. Finally, we propose a security model for control systems of metropolitan infrastructure.

• Journal of the Korean Regional Science Association
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• v.37 no.2
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• pp.49-61
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• 2021

Long-distance commuting is a problem as people living in Gyeonggi-Incheon contitue to commute to Seoul in the Seoul metropolitan area. To solve this problem, policies in the region are aiming for a self-sufficient zone formation plan and a compact city. However, urban problems caused by such long-distance commuting continue. This appears to be due to excessive density and Seoul-dependent networks. However, existing studies have focused on individual cities despite the importance of inter-city interactions, and had limitations in not considering the characteristics of the Seoul-dependent networks. Therefore, the purpose of this study is to empirically analyze the effect of the compactness on commuter travels by comprehensively considering the interactions between cities within the region using multiple regression. As a result of the analysis, it was found that that commuting efficiency increases when a network of more than a certain size is formed, and the results imply that policies should focus on fostering network centers in Incheon and Gyeonggi regions, which are outside the metropolitan area, and consider to expand the transportation networks at the regional level.