• 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.

• Journal of the Korean Operations Research and Management Science Society
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• v.30 no.3
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• pp.119-135
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• 2005

Design of location erea(LA) in a cellular network is to partition the network into clusters of cells so as to minimize the cost of location updating and paging. Most research works dealing with the LA design problem assume that the call. arrival rate and mobile flow rate are fixed parameters which can be estimated independently. In this aspect, most Problems addressed so far are deterministic LA design problems(DLADP), known to be NP hard. The mobile flow and call arrival rate are, however, varying with time and should be treated simultaneously because the call arrival rate in a cell during a day is influenced by the change of a population size of the cell. This Paper Presents a new model on IA design problems considering the time-dependent call arrival and mobile flow rate. The new model becomes a stochastic LA design problem(SLADP) because It takes into account the possibility of paging waiting and blocking caused by the changing call arrival rate and finite paging capacity. Un order to obtain the optimal solution of the LA design problem, the SIADP is transformed Into the DLADP by introducing the utilization factor of paging channels and the problem is solved iteratively until the required paging quality is satisfied. Finally, an illustrative example reflecting the metropolitan area, Seoul, is provided and the optimal partitions of a cell structure are presented.

• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.841-855
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• 2018

The purpose of this study is to estimate the available potential heat source for heat pump in the district heating supply area in the city. Unused energy potentials were estimated and integrated based on open source based data. In particular, geographical spatial analysis of recoverable heat energy density and heat demand in the heat source area of large retailers and public sauna facilities in the DH network located in the southern part of the metropolitan area (Pyeongtaek-si) was conducted. As a result of the study, the DH network area had a total potential energy of 1,741.7 toe/year for the two heat sources of large retailers and public saunas. It is estimated that 1,006.9 toe/year, which is 57.8% of the total, can be linked to the district heating. The large retailers showed a positive correlation with the floor area and energy use of 0.4937. The recoverable energy intensity was estimated to be $0.0017toe/m^2$ per unit area and $0.0069tCO_2/m^2$ for greenhouse gas emissions. In addition, public saunas were analyzed by comparing the empirical case with the theoretical calculation, and it was estimated that energy conservation estimate of 80% was $0.0315toe/m^2$ per bath area and $0.1183tCO_2/m^2$ for greenhouse gas emissions. The total potential energy amount of this area was positively correlated with the heat demand of apartment house by administrative district, and it was confirmed that it had a relatively high potential energy especially in traffic and commercial center.

• The KSFM Journal of Fluid Machinery
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• v.12 no.1
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• pp.28-34
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• 2009

The objective of this study was to draw the most suitable plan of an automatic domestic solid waste collection system for land development area. The results of this study indicated that the most suitable plan is identified as a land development area larger than 3,600,000 $m^2$ located in the metropolitan area with an incinerator system (or MBT). There are the cases smaller than the standard area but this may cause additional allotment from the residents. According to a rating method to compute the size of the most suitable plan, installation of an automatic clean network has to be minimized if the rated score is below 2.0. On the other hand, the installation is required if the rated score is above 2.5. For a certain circumstance, a cautious decision has to be made for installation of the automatic domestic solid waste collection system by considering the influence of the initial cost, sale price, residential allotment, and maintenance cost on the land development.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.569-572
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• 2003

The broadband wireless access industry, which provides high-tate network connections to stationary sites, has matured to the point at which it now has a standard for second-generation wireless metropolitan area networks. IEEE Standard 802.16, with its WirelessMAN air interface, set the stage for widespread and effective deployments worldwide. This paper presents an implementation of media access control that can be applied to BWA (Broadband Wireless Access) system. Medium access control (MAC) is a key issue in multi-access networks where a common channel is shared by many users. The designed MAC prototype roughly consists of MAC Hardware and MAC Software. The MAC Hardware part includes timing process, MAC transmission control, MAC reception control, and CRC/HCS process. The MAC Software part includes control of MAC signaling, network interface, and Physical (PHY) control. The designed MAC protocol will be integrated with the PHY of BWA in future and we can test overall system performance of MAC and PHY.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.5
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• pp.1-15
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• 1993

In DQDB networks, the bandwidth can be increased considerably be using the EN(Erasure Node) algorithms and DR(Destination Release) algorithms. However, the important issue in implementing them is using method of extra capacity fairly. To improve it, this paper proposes AEN(Adaptive Erasure Node) algorithm which erasure function is activated by network traffic load. Its functional architecture consists of SESM, RCSM, LMSM in addition to the basic DQDB state machines (DQSM, RQM). The SESM and RCSM state machines are placed in front of the DQSM and RQM state machines in order for the node to take advantage of the newly cleared slots. This paper also presents some simulation results showing the effect of AEN algorithm on access delay, throughput and segment erasing ratio in the single and multiple priority networks. The results show that the AEN algorithm offer the better performance characteristics than existing algorithms under overload conditions.

• Journal of Korean Society of Transportation
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• v.31 no.1
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• pp.47-56
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• 2013

The present study proposed a methodology to analyze the networking efficiency of arterial road networks. The methodology was motivated to design three-dimensional networks and to analyze the networking ability quantitatively, which is a novel approach compared to existing methods depending on the two-dimensional network definition and the qualitative analysis for improving arterial road networks. The method considered the interdependence between high-level freeways and low-level highways, the ITS-based information for traffic and road conditions, and the physical networking. These three factors were quantified by a networking index (NI), and the networking efficiency was measured by a networking rate (NR). The present study proved that the networking efficiency (NR) was influenced by travel information sharing (i.e., ITS) and physical factors. This supports the fact that the integrated improvements of physical and ITS factors are necessary for an arterial road. The proposed method was applied for an actual arterial road network. It was found that the nation-wide NR was higher than that for the metropolitan area, which might be due to the difficulty in switching between high- and low-level networks and the lack of ITS functions in the metropolitan area.

• Journal of Korean Society of Transportation
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• v.17 no.3
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• pp.73-85
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• 1999

In metropolitan area, intersections having turn Prohibitions are often found and it is important to consider them in path planning. This Paper presents a new path planning method road networks having turn prohibitions. A new road network model is proposed in which an alter-native route for each turn-Prohibition is constructed in off-line using U-turn or P-turn and then Put into road network database. The proposed network model is efficient since it requires no virtual nodes that are usually used in the conventional road networks to represent turns at intersections. In order to find a shortest path with the proposed network, a new shortest path algorithm is proposed. A knot for the turn-Prohibited node is newly defined and is used in comparing the cost of the alternative route with that of the other path.

• Electronics and Telecommunications Trends
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• v.33 no.3
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• pp.1-10
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• 2018

This article presents spectrum sharing policy trends both overseas and domestically. The Federal Communications Commission recently adopted rules for the commercial use of a 150 MHz bandwidth at 3.55 to 3.7 GHz, which has been utilized for defense and satellite services. This frequency band for spectrum sharing is called the citizens broadband radio service (CBRS) band. In Europe, the related regimes for licensed shared access application at 2.3 to 2.4 GHz has been organized, and interface standardization for sharing frequency information has been completed. In Korea, efforts are being made to establish spectrum-sharing policies to improve the efficiency of the frequency utilization. This article also introduces both the IEEE 802 local area network/metropolitan area network and 3GPP standardization activities with regard to frequency sharing technologies. To effectively solve the spectrum-sharing problem in IEEE 802, standardization activities on the CBRS and the mid-band (3.7-24 GHz) are underway. 3GPP is currently developing the standardization of a licensed assisted access technology, which extends mobile communication services provided in the licensed band to unlicensed bands.

• Journal of the Society of Disaster Information
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• v.10 no.2
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• pp.192-198
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• 2014

In the current times, large-scale disasters, such as the recent sinking of Se-Wol ferry, are occurring continuously and unexpectedly. In order to minimize damage in the disaster scene, quick delivery and sharing of information between crisis management agencies is one of crucial factors that determine the scale of the damage. However, ineffective communication persists between the agencies in disaster scenes where disaster management action has to be carried out urgently. For that, this research focused on the actual condition of the inter-agency communication method and wireless operations, and also suggested the building plan of effective and efficient networking through understanding of each agency's present state and duties.