• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.8
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• pp.3054-3067
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• 2015

The phenomena of higher channel cross polarization discrimination (XPD) is mainly observed for future wireless technologies such as small cell network and massive multiple-input multiple-output (MIMO) system. Therefore, utilization of high XPD is very important and space-polarization division multiple access (SPDMA) with dual-polarized MIMO system could be a suitable solution to high-speed transmission in high XPD environment as well as reduction of array size at base station (BS). By SPDMA with dual-polarized MIMO system, two parallel data signals can be transmitted by both vertically and horizontally polarized antennas to serve different mobile stations (MSs) simultaneously compare to conventional space division multiple access (SDMA) with single-polarized MIMO system. This paper analyzes the performance of SPDMA for maximum ratio transmission (MRT) in time division duplexing (TDD) system by proposed dual-polarized MIMO spatial channel model (SCM) compare to conventional SDMA. Simulation results indicate that how SPDMA utilizes the high XPD as the number of MS increases and SPDMA performs very close to conventional SDMA for same number of antenna elements but half size of the array at BS.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.564-565
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• 2019

The Internet of Things technology is regarded as the next major technology that will be the driving force behind the fourth industrial revolution. The characteristics of entities for Internet of Things application are changing more actively and actively, requiring a more detailed approach, but existing access control technologies are designed around users, requiring access control techniques that maintain efficiency and security with less system load to apply complex and variable content. Therefore, research on role-based access controls that are appropriate for Internet of Things entities is essential. In this study, the relevant research for the study of access control of the Internet of Things entities and the RBAC and AC methods that can define the properties of the various entities within the Internet of Things.

• Journal of the Society of Disaster Information
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• v.10 no.1
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• pp.49-60
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• 2014

For the demand analysis of Metropolitan Train Express project, the catchment area of station should be reevaluated considering the journey speed of it. In this paper, we estimated travel mode choice model using stated preference data including Seoul metropolitan express train and compared the parameters of access/egress travel time between existing metro and Seoul metropolitan express train. The parameter of Seoul metropolitan express train is 2.5 times smaller than that of existing metro. Consequently, the catchment area can be expanded in same proportion. It can be concluded that the result of demand forecasting can be increased by 10% accommodating the expanded catchment area.

• Journal of Advanced Navigation Technology
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• v.23 no.6
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• pp.589-596
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• 2019

With the proliferation of intelligent transportation system (ITS) with dedicated short-range communication (DSRC) deployment, there are various applications requiring different throughput and reliability performance. To meet the enhanced throughput requirements in newly generated applications, IEEE 802.11bd is proposed to standardize for support of enhanced throughput and latency, preserving the fairness with previously deployed WLAN V2X devices. One of the main features of IEEE 802.11 bd is 20 MHz transmission to support the high data rate. In this paper, the primary channel selection method is proposed to guarantee the fairness with frame transmissions with 10 MHz bandwith including communications in WLAN V2X devices deployed with IEEE 802.11p. Simulation shows that the proposed channel access method for 20 MHz transmission with primary selection preserves the fairness without the change of channel access method in wide-band transmission.

• Journal of the Korean Society for information Management
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• v.29 no.1
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• pp.135-156
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• 2012

The purpose of this study is to ascertain librarian's perceptions on their users' library access and its patterns. Interviews with seven library staff reveal physical accessibility issues including spatial relationships between libraries and other facilities such as shopping malls and schools, travel distance, transportation mode, and temporal perspectives of library access. The results from the interviews corroborate the findings from secondary analysis using household travel data. However, interviewees do not have a clear picture of how much their users travel and spend to access their libraries. This is true, even though these factors are critical to analyze physical accessibility. Based on the findings, this study makes recommendations to improve the accessibility of public libraries. Suggestions include the concept of sponsorships with other facilities, the placing of material drop-boxes on the main route, and providing library programs during lunch time.

• Journal of Korean Society of Rural Planning
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• v.25 no.1
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• pp.51-65
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• 2019

This study developed diagnostic system to understand the level of welfare cultural service and infrastructure in rural areas. The applicability was reviewed through the Delphi survey and the sample survey of 60 villages. The diagnostic indicators consist of three areas: the demand area, supply area, and delivery area. The demand area consists of 8 indicators, 25 indicators for welfare services and infrastructure (healthcare, social welfare) and 32 indicators for cultural services and infrastructure (culture, education, leisure sports). The service delivery area was divided into service supply area access and traffic accessibility (public transport use status and rural transport model status) by each indicator. A diagnostic system was applied to 60 villages. Services and infrastructure for rural welfare and culture were supplied more in the Si area than Gun area. The delivery area was easier to access the Gun area than Si area. In the case of traffic access, public transportation was more frequently used in the Si area than Gun area, and the rural transportation model was found to have a relatively large amount in the Gun area compared to Si area. The diagnosis system about services and infrastructure for rural welfare and culture will provide information necessary for establishment and decision making of regional development policy taking into account characteristics of rural areas in the future.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.5
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• pp.61-72
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• 2013

Next-generation ITS(Intelligent Transportation System) adopts WAVE(Wireless Access in Vehicular Environment) system which is capable of the bidirectional communication system in vehicular environments. u-Transportation system adopted WAVE communications system to show the optimal performance in terms of various services with regard to vehicle safety and traffic. In this paper, we introduce testbed of ubiquitous-Transportation system and its service. Then, we describe WAVE system for supporting next-generation ITS service. Also, we carried out tests in real road environments in order to verify communication functions of WAVE systems and its performance. We confirmed that our communication systems for supporting services meet the communication performance.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.4 no.2 s.7
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• pp.23-31
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• 2005

ITS(Intelligent Transportation System) implementing information collection services and information support services for cars of moving fast needs a communication system of special aim such as RF-DSRC(Radio Frequency Dedicated Short Range Communication). Before RSE(Road Side Equipment) and OBE(On-Board Equipment) will be able to communicate RF-DSRC, OBE first have to request Link Initialization Access using ACTC(Activation Channel) in allocated ACTS(Activation Slot) by Slotted ALOHA. Even though Link Initialization Access is a important element to decide performance of communication system, optimal mathematic modeling study of Link Initialization Access which is adapted RF-DSRC characteristics is not enoush. So, in this paper, we propose mathematical modeling about Link Initialization Access of RF-DSRC. And then we computed Link Initialization Access probability defining offer load(G) which is adapted RF-DSRC characteristics for analyzing performance of modeling.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.725-733
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• 2018

With urbanization projects involving trunk roads progressing, many simple interchanges, which separate passing traffic into the main traffic and access subtraffic, are being constructed to maximize the traffic capacity. Under the current Road Connection Rule, the access-prohibited section in an interchange is determined based on the access lane and limit distance in the complete interchange road, but separate criteria for the simple interchange are not defined. This may cause confusion in the Road Management Office's determination of the access-prohibited section in the simple interchange, or lead to the application of the criteria for the access-prohibited section in the complete interchange without considering the features of such interchange. This study conducted a comparative analysis of the domestic and overseas systems related to the installation of access section in trunk roads, such as general national roads. This paper presents a survey of the methods for applying the access-prohibited section in the interchange along with the actual cases and proposes improvement measures for a rational calculation of the access prohibited installation section in the simple interchange to minimize the downsides associated with the application of the extremely strict criteria. The proposed road connection rule improvement measures based on the consideration of the purpose of installing the simple interchange and on the consideration the features of the simple interchange are expected to prevent administration confusion by the field road management offices as well as the waste of unnecessary efforts and costs by petitioners so they can boost the service satisfaction for people and the administrative reliability.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.2
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• pp.55-60
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• 2010

The purpose of this study is to analyze compact city planning indicators that have influence on public transportation commuting of residents in the 54 medium and small-sized cities. In the study, land use and transportation infrastructure of cities and other socio-demographic variables are used as explanatory variables in a causal model. 96,552 subjects from 54 cities in korea are selected as the final sample, and a statistical analysis is carried out by applying Random Intercept Logit Model. Analysis shows that a high level of density and jobs-housing balance in the city results in more public transportation commuting. And higher access to bus and subway station influence commuting, so subway & bus stop are important factors to increase public transportation commuting