• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2808-2813
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• 2011

According to opening the domestic existing lines and High-Speed Lines(HSL) depending on each section and phase-in, there were constructed in railway over state-of-the-art radio communication networks. Therefore, there have been 3 wireless communication networks in domestic railways in accordance with running sections as like VHF, TRS-ASTRO and TRS-TETRA. For instance, the VHF networks were constructed in exsiting lines and TRS-ASTRO were Kyungbu HSL phase-1 except Seoul-Kwangmyung section, downtown in Daejeon City and that of Daegu City. And it was constructed in DongDaegu-Busan section of Kyungbu HSL phase-2, Osong-Kwangju section of Honam HSL phase-1 and would be done in Kwangju-Mokpo of Hanam HSL phase-2 and Soosu-Pyungtaek of Metropolitan Area Line by TRS-TETRA. In this paper, we described some important problems of radio communication management and investigated current state of radio communication for railways. Moreover, we presented the necessity of integrated radio networks for domestic railways.

• Smart Media Journal
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• v.13 no.2
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• pp.108-121
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• 2024

In the IT industry, the complexity and volatility of corporate networks are gradually evolving, and concurrently, the significance of corporate networks is increasing. Previous research has employed network analysis to scrutinize inter-corporate trade relationships for strategic and policy making. However, previous studies focused on the overall network structure from a macroscopic perspective, presenting limitations in applicability at the individual IT corporation level. This study develops a novel research model incorporating sector and region-level network analysis based on connection strength, along with the derivation of a composite node centrality indicator. Using this methodology, we analyzed corporate networks across nine metropolitan areas using IT corporate transaction data. The results means that cities with a manufacturing base, such as Incheon, Busan, and Daegu, have recently established cooperative networks with IT companies. We also found that in the IT industry in Gwangju and Daejeon, certain companies dominate the transaction network.

• Journal of the Economic Geographical Society of Korea
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• v.17 no.1
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• pp.98-113
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• 2014

The purpose of this study is to investigate the changes in the accessibility of the Metropolitan Seoul Transit systems since 2000, in which many new subway lines have been constructed as well as other urban transit lines have been connected to the systems. We suggest an accessibility measure model for Un-fixed Transportation Networks. In order to measure the nodal accessibility based on the mobility, we apply path-distance, physical-distance, and time-distance as the distance impedance measurement. Specifically, we develop time-distance algorithms to measure the time-distance between each pairs of transit stations based on the T-card transaction databases. We apply the model to the Metropolitan Seoul Transit systems in two time points(2005 and 2011). We examine the results in terms of three distance accessibility measures. Time-distance accessibility explains better the urban land use patterns in the Metropolitan Seoul area than the other two. We visualize the spatial patterns of time-distance accessibility by applying GIS, and analyze the spatial structures of accessibility in the Metrropolitan Seoul area between two time points.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.2
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• pp.113-121
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• 2014

Objectives: This study is intended to seek credible and efficient measurements on airborne asbestos concentrations that allow immediate action by establishing complementary data through comparative analysis with existing PCM and KF-100 method real-time monitoring equipment in working areas in Seoul where asbestos-containing buildings are being demolished, including living environment surroundings. Materials: We measured airborne asbestos concentrations using PCM and KF-100 at research institutes, monitoring networks, subway stations and demolition sites of asbestos-containing buildings. Through this measurement data and KF-100 performance testing, we drew a conversion factor and applied it via KF-100. Finally we verified the relationship between PCM and KF-100 with statistical methods. Results: The airborne asbestos concentrations by PCM for the objects of study were less than the detection limit(7 fiber/$mm^2$) in three (20%) out of 15 samples. The highest concentration was 0.009 f/cc. The airborne asbestos concentrations by PCM in laboratories, monitoring networks, subway stations and demolition sites of asbestos-containing buildings were respectively $0.002{\pm}0.000$ f/cc, $0.004{\pm}0.001$ f/cc, $0.009{\pm}0.001$ f/cc, and $0.002{\pm}0.000$ f/cc. As a result of KF-100 performance testson rooftops, the conversion factor was 0.1958. Applying the conversion factor to KF-100 for laboratories, the airborne asbestos concentrations ratio of the two ways was nearly 1:1.5($R^2$=0.8852). Also,the airborne asbestos concentration ratio of the two ways was nearly 1:1($R^2$=0.9071) for monitoring networks, subway stations, and demolition sites of asbestos-containing buildings. As a result of independent sample t-tests, there was no distinction between airborne asbestos concentrations monitored in the two ways. Conclusions: In working areas where asbestos-containing buildings are being demolished, including living environment surroundings, quickly and accurately monitoring airborne asbestos scattered in the air around the working area is highly important. For this, we believea mutual interface of existing PCM and a real-time monitoring equipment method is possible.

• Korean Journal of Human Ecology
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• v.22 no.3
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• pp.421-436
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• 2013

International marriage is composed over 10% among total marriage in Korea. This study tried to know what kinds of social networks, especially transnational networks, the immigrant wives use for the process of being married and for the adjusting to marriage and Korean culture, and how their Korean families also are affected by the transnational networks. For the purposes of this study FGI and the interviews were applied for the immigrant wives, the multicultural husbands and the specialist groups in metropolitan city DaeGu. 18 migrant interviewees from Vietnam, China, Philippine, etc. were collected by the snow-ball sampling. 5 husbands were collected from the self-help meeting in multicultural families support center. The transnational networks of the immigrant wives in DaeGu were deterritorialized and reterritorialized actively. Migrant wives managed the close relationship with their family members of motherland, and had the networks sticky with relatives, friends, and other fore-immigrant wives from the same countries. Their migrations are characterized as 'chain migration'. Even though they acquired the Korean nationality, they have the transnational identities. They and their Korean families are interrelated and internetworked in exchanging economic resources as goods and money, human beings, love, child caring, foods and culture over local boundaries.

• Journal of Communications and Networks
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• v.7 no.2
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• pp.207-221
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• 2005

The proliferation of wireless local area networks (WLANs) offering high data rate in hot spot area have spurred the demand for possible WLANs and third-generation (3G) cellular network integration solutions as the initiative step towards 4G systems. This paper provides a novel architecture for seamless location-aware integration of WLANs into 3G cellular networks and also an analysis for the efficient handover techniques. We introduce location as a key context in secure roaming mechanism for context-aware interworking in 4G systems. The fast secure roaming with location-aware authentication is implemented at an entity called location-aware service (LAS) broker that utilizes the concepts of direction of user and pre-warming zone. The location-ware interworking architecture supports seamless roaming services among heterogeneous wireless networks including WLANs, wireless metropolitan area networks (WMANs), and 3G cellular networks. This paper also includes a description of procedures needed to implement efficient mobility and location management. We show how the LAS broker with pre-warming and context transfer can obtain significant lower latency in the vertical handover.

• Korean Journal of Human Ecology
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• v.21 no.3
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• pp.469-488
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• 2012

International marriage is composed over 10% among total marriage in Korea. Korea is changing rapidly to the multi-cultural society. The researches need to inquire into what the state of 'ethnic communities of the immigrant wives as the minorities' is and how the immigrant wives build and develop the ethnic networks longitudinally. At the beginning, this study tried to know what kinds of social networks the immigrant wives use for the process of being married and for the adjusting to marriage and Korean culture. For the purposes of this study FGI and the interviews were applied for the immigrant wives and the specialist groups in metropolitan city DaeGu. 18 interviewees from Vietnam, China, Philippine, etc.. were collected by the snow-ball sampling. The social networks of the immigrant wives in DaeGu were mainly private, but were deterritorialized and reterritorialized actively. They managed the close relationship with their family members of motherland, and had the networks sticky with relatives, friends, and other immigrant wives from the same countries. Even though they acquired the Korean nationality, they have the transnational identities. But the internet environment of Korea can contribute to activate the social networks for the ethnic communities of the immigrant wives.

• Journal of Korea Planning Association
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• v.54 no.3
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• pp.63-74
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• 2019

Korean government has implemented policies to strengthen the competitiveness of small and medium sized cities. However, since it is often difficult to enhance the competitiveness through individual projects, many local governments in metropolitan areas are working together to pursue local growth. On the other hand, small and medium sized cities that are not included in metropolitan areas due to their spatial limitations have difficulties in implementing effective growth policies. Given this background, the purpose of this study is to identify the functional correlation based on urban interactions and develop functional econometric model for the economic growth of small and medium sized cities. This study uses spatial econometrics models and functional weight matrix to identify the effects of functional networks on small and medium sized cities. The results show the effect of functional networks on the growth of small and medium sized cities and provide policy implications for regional spatial planning that addresses effective management of small and medium sized cities.

• Journal of the Korean Geographical Society
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• v.51 no.4
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• pp.541-558
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• 2016

Landfill has been a long pending issue in the Seoul Metropolitan Region since it was created. Adopting Painter's notion of "territory-effect," this paper analyzes the network formation and change of diverse actors and territory as an effect of networked relations according to four periods from the creation of the landfill to current extension of landfill use. The results are as followed. First, the network formation and composition of major actors has been changed together with historical-geographical conditions. Second, these networks created territory as an effect and re-articulated the configuration of conflicts and solidarity of diverse actors. Third, territory created as an network-effect are different in each period, and is continuously reterritorializing. These findings suggest that territory is never complete and always in the making.

• Journal of the Korean Regional Science Association
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• v.33 no.1
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• pp.29-41
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• 2017

This study proposes an integrated accessibility measurement algorithm, which is applied to the Seoul Metropolitan public transportation system consisting of bus and subway networks, and analyzes the result. We construct a public transportation network graph linking bus-subway networks and take the time distance as the link weight in the graph. We develop a time-distance algorithm to measure the time distance between each pair of transit stations based on the T-card transaction database. The average travel time between nodes has been computed via the shortest-path algorithm applied to the time-distance matrix, which is obtained from the average speed of each transit route in the T-card transaction database. Here the walking time between nodes is also taken into account if walking is involved. The integrated time-distance accessibility of each node in the Seoul Metropolitan public transportation system has been computed from the T-card data of 2013. We make a comparison between the results and those of the bus system and of the subway system, and analyze the spatial patterns. This study is the first attempt to measure the integrated time-distance accessibility for the Seoul Metropolitan public transportation system consisting of 16,277 nodes with 600 bus routes and 16 subway lines.