• Journal of the Society of Disaster Information
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• v.17 no.3
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• pp.655-666
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• 2021

Purpose: This study is to develop a method for measuring dynamic speeding risks using vehicle trajectory big data and to demonstrate the feasibility of the devised speeding index. Method: The speed behaviors of vehicles were analysed in microscopic space and time using individual vehicle trajectories, and then the boundary condition of speeding (i.e., boundary speed) was determined from the standpoint of crash risk. A novel index for measuring the risk exposure of speeding was developed in microscopic space and time with the boundary speed. Result: A validation study was conducted with vehicle-GPS trajectory big data and ground-truth vehicle crash data. As a result of the analysis, it turned out that the index of speeding-risk exposure has a strong explanatory power (R²=0.7) for motorway traffic accidents. This directly indicates that speeding behaviors should be analysed at a microscopic spatiotemporal dimension. Conclusion: The spatial and temporal evolution of vehicle velocity is very variable. It is, hence, expected that the method presented in this study could be efficaciously employed to analyse the causal factors of traffic accidents and the crash risk exposure in microscopic space using mobility trajectory data.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.4
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• pp.13-21
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• 2011

Update of road facilities database such as road sign, traffic lights, and street lights is interesting business in a local government. Recently, existing road facilities database, aerial photo and topographic map are referred for the installation and complement of road facilities. But it is difficult to comprehend road facilities' condition and additional expenses may appear in field survey. Therefore, it is necessary to establish and update road facility DB and many studies has been carried out to efficiently collect road related spatial data. In this study, the establishment of various complicated road facility DB was conducted by images that had been obtained by digital camera with a built-in bluetooth and DGPS. Results showed that road facility DB was constructed effectively and suggested the possibility of road facility management using images based on coordinate through accuracy analyses using total-station surveying. And using digital camera and DGPS is expected to effective real-time update and management of road facility DB.

• Information Systems Review
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• v.10 no.2
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• pp.97-121
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• 2008

There are relatively inactive discussions about applying ubiquitous technology (uT) to traditional marketplace. If u-Market which affords to promote customer shopping convenience and on/offline shopping experience is implemented, then traffic of visiting customers as well as the revenue of the market will increase. Ultimately, it will lead to revitalizing traditional market. For this purpose, we developed a realistic u-Market service scenario with restricted uT considering spatial limitation and poor infrastructure of the physical marketplace. Based on u-Market service scenario, we have empirically investigated the determinants of u-Market service acceptance of the actual customers of traditional marketplace. We hope the results of this study will help in improvement of u-Market system development and service feasibility.

• Journal of the Korean association of regional geographers
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• v.14 no.6
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• pp.718-735
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• 2008

Park-and- Rides are intermodal transfer facilities providing a staging location for travellers to transfer between transportation modes. They are an alternative to alleviate transportation problems such as traffic congestion and air pollution in metropolitan areas. Siting Park-and-Ride facilities belongs to a kind of multi-criteria spatial decision making problems being associated with a combination of various location factors. The purpose of this paper is to provide a method and procedure to evaluate the location suitability of Park-and-Ride facilities using GIS(Geographic Information Systems). Using GIS-based suitability analysis, land value, landuse, road accessibility, public transportation accessibility, possibility to intercept automobile trips, distance to activity center and competition with existing facilities were evaluated as location factors. The suitabilities of individual factors were combined to produce a composite map with a specific weight scheme. Then a given number of sites with high suitability score were selected as potential facility locations and their demand were evaluated based on a commutershed with parabolic shape. The suggested method and procedure will provide useful information in determining Park-and-Ride sites and designing their structure.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.11
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• pp.2447-2458
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• 2009

Ad hoc wireless networks operate without any infrastructure where a node can be a source and a router at the same time. This indispensably requires high throughput and low delay performance throughout the wireless network coverage span, particularly under heavy traffic conditions. Recent research on using multiple antennas in beam-forming or multiplexing modes over a wireless channel has shown promising results in terms of high throughput and low delay. Directional antennas have shown to increase spatial reuse by allowing multiple transmitters and receivers to communicate using. directional beams as long as they do not significantly interfere with each other. However directional antenna performance asymptotically approaches the omni-directional performance in a high density ad hoc network. Simulation results in QualNet validate that average throughput and packet corruption ratio of directional antenna approach omni-directional performance. Moreover, we further highlight some important issues pertaining to the directional antenna performance in wireless networks.

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.205-209
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• 2008

The current representative supporting tool for seeing an exhibition is PDA, which is an information provider that is being activated in famous galleries in the world. It has been successful in making spectators' traffic line for exhibition free and in Overcoming time and spatial restrictions, but it still provides uniform information. And the field of its activities is 'inside' of an exhibition hall so it has some limitations in terms of two-directional communication. In order to overcome such limitations, this study intends to deduce applications for the activation of continuous communication in the changing exhibition environment from before spectators see an exhibition to after they see an exhibition, to design a prototype, and further, to improve the level of the exhibition culture.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6B
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• pp.517-526
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• 2006

In order to achieve high capacity and reliable link quality in wireless communication, the significant efforts should be concentrated on mitigating interference between cells. To solve the interference problem, the newly introduced concept of a Distributed Wireless Communication System (DWCS) can provide the capability of joint control of the signals at multiple cells. This paper proposes a new concept of virtual cell: the Dual Virtual Cell (DVC), and also proposes DVC employment strategy based on DWCS network. The proposed system manages two kinds of virtual cell. One is the Active Virtual Cell which exists for user's actual data traffic and the other is the Candidate Virtual Cell which contains a set of candidate antennas to protect user's link quality from performance degradation or interruption. The proposed system constructs DVC by using antenna selection method. Also, for multi-user high-rate data transmission, the proposed system introduces multiple antenna technology to get a spatial and temporal diversity gam and exploits space-Time Trellis Codes known as STTC to increase a spectral efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8C
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• pp.731-741
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• 2009

Optical repeater is often installed at the isolated area. Spatial separation makes it possible to reduce the inter-code interference when secondary scrambling codes are used for traffic connected through repeater. In this paper, we propose five secondary scrambling code usage scenarios with the aids of optical repeater to maximize the user capacity. In order to evaluate the performance, dynamic system level simulation is performed. We also propose a base station-repeater switching where each active users can change access points by comparing the channel condition from base station and repeater thorough secondary common pilot channel (S-CPICH) signal to noise-interference ratio (SINR). Moreover, primary-secondary scramble code replacing scheme is proposed which replaces secondary scramble code with primary scramble code when a call using primary scramble code is ended and its corresponding OVSF code is available to users using the secondary scramble code

• The Journal of the Korea Contents Association
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• v.6 no.1
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• pp.72-79
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• 2006

Recently, a MMORPG(Massively Multi-play Online Role Playing Game) has built distribute server by Seamless world. This paper proposes an efficient collision detection method. DLS is used to dynamically adjust spatial subdivisions in each the boundary regions of distribute server We use an index table to effectively utilize the relationships between in the nodes and can perform the collision detection efficiently by reconstructing nodes of the tree. Also, we maintain the information for the boundary region to efficiently detect the collections and adjust the boundary regions between distributed servers by using DLS. As the DLS uses pointers, the information for each server is not needed and the boundary regions between the distributed servers are efficiently searched. Using node index points, the construction table can be made to find between ray and neighborhood node, In addition, processes for Network traffic reduce because a copy of the boundary regions is not needed when a object moves with realtime.

• Journal of the Korean Association of Geographic Information Studies
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• v.10 no.4
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• pp.189-197
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• 2007

GIS is the tool widely used for the practical solution of spatial problems in every region regardless of the language and ideology. In this paper research trends and tendencies of GIS in North Korea are reviewed compared with those in South Korea. For this purpose, academic publications on GIS in North Korea are surveyed and classified according to main subjects in GIS. Such classification by main subjects of GIS in North Korea are conducted on the basis of the classification of research trends and tendencies of GIS in South Korea. As a result, researches in North Korea are mainly focused upon such fields as geodetic surveying and measurement, map manufacture, atmospheric phenomena, agriculture and disasters, while there are few studies related to such fields as national GIS policy and circulation, GIS education, internet-based GIS, and traffic, to name but a few. Most parts of applied data are based on low and medium resolution image such as meteorological satellite images, Landsat images, and so on. This reflects the low level of the development of GIS DB infrastructure in North Korea.