• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.127-131
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• 2002

This paper presents the a measured path-loss characteristics in urban line-of-sight(LOS) and non line-of-sight(NLOS) environments for 3.4, 5.3, and 6.4 ㎓ band signals. A two-ray model is applied to analyse the path-loss characteristics in LOS areas. In LOS areas, an empirical break point, whose distance is shorter than a theorical break point, is founded. Further, a sudden power level drop occurs at a transition point from LOS region to NLOS area and different path-loss exponents are occured various cases. The power level drop due to comer loss and path-loss exponents both increase as the distance between the transmitter and the corner increases.

• International Journal of Highway Engineering
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• v.17 no.2
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• pp.123-134
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• 2015

PURPOSES : The key point of a multimodal LOS (level-of-service) evaluation system is that all of the modes are mutually associated to determine each mode's LOS. For example, the LOS of the bicycle mode is measured based on not only bicycle volumes, but also automobile volumes. However, the Korea Highway Capacity Manual (KHCM) still focuses on the automobile mode in evaluating the LOS of the roads. Additionally, the KHCM's LOS of the other modes, except for the automobile, is not consistent with actual road conditions. The KHCM, therefore, needs to develop and introduce a multimodal LOS system in order to evaluate the service conditions more accurately. METHODS: As a preliminary step to the introduction of multimodal LOS research, in this study the current problem of the KHCM's LOS system through a close review and comparison with other HCMs (highway capacity manuals) was identified. Secondly, a field survey and investigation of the urban streets to apply the HCM's multimodal LOS system was conducted. Finally, a comparison analysis of the results of the HCM and KHCM LOS was performed. RESULTS: In the study, it was found that the results of the LOS for the automobile mode did not show a significant difference between the HCM and KHCM. However, the LOS of the bicycle and pedestrian mode tended to be worse in the multimodal LOS system, which results from considering the effects of the automobile mode. Moreover, it was found that many cases have the potential to improve the overall LOS conditions, while reducing the automobile capacity. CONCLUSIONS: With the introduction of the multimodal LOS system, road diet and complete streets can be easily applied to ans actual road improvement project. Ultimately, the multimodal LOS system should be introduced into the KHCM, which can then be applied to traffic impact studies and other road improvement projects for more accurate evaluations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.9
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• pp.2494-2504
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• 1996

This paper describes about the spread specturm radio wave propagation characteristics in urban microcells. The experiments are carried out with respect to the mean excess delay, the RMS delay spread, and the received maximum peak power in the two kinds of geogrphical areas, LOS area and N-LOS area, especially whose variations are observed while varying the transmission distance and tilting the transmitting antenna. The typical results obtained in pariticular urban sites in Seoul are 300-600 nsec of mean excess delay and about 75 nsec of averaged RMS delay spread for LOS area, and 270-280 nsec of mean excess delay and about 100 nsec for N-LOS area. With the transmitting antenna gilted, obsered in the experiments are increase in RMS delay spread as expected, but increase of the received power at N-LOS areas in particular.

• International Journal of Highway Engineering
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• v.14 no.6
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• pp.75-84
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• 2012

PURPOSES : This paper aims to improve the evaluation method of the Level of Service(LOS) for urban streets presented by the current Korean Highway Capacity Manual(KHCM) and suggest its utilization plan as a part of the methods to evaluate the sustainability of a transportation policy. METHODS : This paper carried out a research in 3 steps to develop a new evaluation method. First of all, this paper reviewed the previous studies related to the LOS of urban streets and the socially requested items for a sustainable transportation system. Then this paper derived an index and weight through expert questions to select an evaluation index. Lastly, this paper compared the results according to the existing evaluation methods with the new evaluation methods through case studies. This paper used an Analytic Hierarchy Process(AHP) for importance analysis and weight selection between new evaluation items and indices, and applied a Grey System Theory(GST) for a synthetic and integrated evaluation between the selected evaluation indices. RESULTS : As a result of evaluating the LOS according to the existing evaluation methods and the integrated evaluation methods using a GST through case studies, it was analyzed that new methods' results are less than or equal to the existing evaluation methods; and as a result of applying a weight between evaluation indices according to AHP, it was noticed that the total score seems to rise more when the LOS in the existing evaluation is calculated lower. It was analyzed that the LOS calculated by reflecting the newly established evaluation items and the importance between indices in this study has difference from the LOS of the existing urban streets. CONCLUSIONS : It is expected that this evaluation method can diagnose the current conditions when establishing a future sustainable traffic system and can be used for the measurement of the sustainability effects of the improvement plans and so on.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.3D
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• pp.335-345
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• 2009

Generally, density is used as a measure of effectiveness (MOE) of the level of service (LOS) for the basic segment of the roadway facility, but can not express the operational condition of the roadway facility properly because there can be an error in the computed density compared with the density measured in the field. Thus, the purpose of this study is to investigate the real-time traffic characteristic data (traffic flow, speed, occupancy, headway, spacing, etc.) from the detectors installed on the mainline section of urban freeway under the study, analyze the maximum flow rate from the relationship between the real-time traffic characteristics collected, and evaluate the LOS criteria within the basic segment of the urban freeway based on the relationship between the occupancy and the v/c ratio depending on the level of service.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.2
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• pp.15-22
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• 1996

This paper presents the generalized method of the prediction of the LOS propagating characteristics in an urban microcell by using theray tracing technique. Whereas the received power is calculated by the finite number of pths, 4~10, on an urban steet, the RMS delay spread is comuted by using the sufficient rays of convergence. To take into account the infinite number of paths the technique of the numbering scheme of image antennas was presented by using the rectangular pulse. As to this the existing restriction of the finitte number of paths was relaxed. based on the method of extending the number of paths and the canyon model the received power and RMS delay spread are computed and their differences according to the number of paths are compared at the frequencies of both 1GHz and 2GHz, respectively.

• Journal of the Korean Society for Railway
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• v.13 no.3
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• pp.339-348
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• 2010

The government continues to make efforts to improve effectiveness, integration and connectivity of public transportation systems. But there have been only a few studies about it. This paper addresses the quality evaluation of pedestrian facility service in transfer stations at urban railroad. LOS (Level Of Service) model of urban railroad by facility based on the body ellipse and density recalculated considering the recent Korean body standard and the suggested Pedestrian Moving Equivalent (PME) and Pedestrian Waiting Equivalent (PWE). For LOS model for the ticket booths and ticket vending machines, queuing theory has been applied to determine LOS of Pedestrians. And the importance weights among the pedestrian facilities is obtained by applying AHP analysis. Lastly, this paper shows and discusses the evaluation results of overall LOS of pedestrian facilities of five urban railroad transfer stations in Seoul.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.3
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• pp.305-317
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• 2015

The function failure of present major facilities is likely to lead to failure of related systems and/or whole facilities, increasing the necessity for protection of infrastructures, main structures, and major industrial facilities. In addition, safe and efficient management for urban infrastructure (waterworks and sewerage facilities, electricity, telecommunications, roads, etc) installed in the basement or on large cities grounds at various public areas is required. Recently in response to this demand, efforts for vitalizing asset management are being made such as enacting related laws and developing asset management system in the U.S., Australia, Europe and other advanced countries with the concept for a new maintenance. In our county, identifying maintenance system problems such as aging and rapid increasing of existing infrastructures and decision-making about updating maintenance is required for systematic and organizational maintenance. In this study, by comparing and observing the LOS(Level of Service) of each countries' waterworks and risk-based LOS, we suggest the direction of future urban water infrastructure management systems for more effective management.

• Journal of Korean Society of Transportation
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• v.25 no.2 s.95
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• pp.83-93
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• 2007

Pedestrians and vehicle users should be treated with equal importance in urban street design. However, current street design suggests that the design criteria for sidewalks is based on the functional hierarchy of the vehicles, therefore it is necessary to develop sidewalk design standards that give more weight to pedestrians rather than vehicles. For this, this study suggests that the level of service of pedestrians should be considered in the process of designing sidewalks. Currently, level of service (LOS) criteria for pedestrians in the Korean Highway Capacity Manual are based on pedestrian volume, but the volume of pedestrians is seldomly estimated in practice. So, the current LOS criteria has limitations in terms of practical use. Also, the study assumes that the pedestrian flow rate is hardly the dominant factor that could affect the LOS of pedestrians at most urban sidewalks. In this context, the study considers a new LOS for sidewalk design based on the comfort of pedestrians while passing pedestrians coming from the opposite direction. Then the study attempts to link the new LOS criteria to the land use patterns using data of pedestrian traffic characteristics acquired from the field. In addition to this, the scope in which the suggested criteria can be applied is suggested.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.3
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• pp.529-534
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• 2016

The paper suggests risk management methodology for alleviating casuality accidents at urban railway stations. Risk management deals with countermeasures for reducing accident probability or consequences to reach at the certain level of risk. First of all, Economic evaluations using cost and benefit for all the alternatives are performed. The alternatives exceeding B/C ratio greater than 1, each alternative is applied in the order of higher B/C ratio. this process is repeated when the level of risk is reduced as low as reasonably practical (ALARP). In order to determine the level of ALARP, Level of Service (LOS) for casuality risk at urban railway stations is proposed. The ALARP level is set to the LOS "C". Finally, a case study is applied to the Jongno 3-ga station, which is a highest risky station among all the stations operated by Seoul Metro and Seoul Metropolitan Rapid Transit Cooperation (SMRT).