• Journal of Sensor Science and Technology
• /
• v.33 no.2
• /
• pp.93-97
• /
• 2024

With the development of promising future mobility and urban air mobility (UAM) technologies, the demand for LIDAR sensors has increased. The SWIR photodetector is a sensor that detects lasers for the 3D mapping of lidar sensor and is the most important technology of LIDAR sensor. An SWIR photodetector based on QDs in an eye-safe wavelength band of over 1400 nm has been reported. QDs-based SWIR photodetectors can be synthesized and processed through a solution process and have the advantages of low cost and simple processing. However, the organic ligands of QDs have insulating properties that limit their ability to improve the sensitivity and stability of photodetectors. Therefore, the technology to replace organic ligands with inorganic ligands must be developed. In this study, the organic ligand of the synthesized PbS QDs was replaced with a MAPI inorganic ligand, and an SWIR photodetector was fabricated. The analysis of the characteristics of the manufactured photodetector confirmed that the photodetector based on MAPI-capped PbS QDs exhibited up to 26.5% higher responsivity than that based on organic ligand PbS QDs.

• Fashion & Textile Research Journal
• /
• v.20 no.1
• /
• pp.63-74
• /
• 2018

The purpose of this study is to investigate the differences in riding characteristics and helmet wearing conditions between bicycle and PMV riders so that the basis data necessary for the development of suitable helmets for each group is provided. For this purpose, riding characteristics and helmet wearing conditions of bicycle and PMV users were investigated using online survey method and then the survey results were interpreted by in-depth interview conducted for bicycle and PMV users. The online survey results showed that the PMV group showed shorter driving distance and more driving frequency than bicycle group. This short driving distance was due to the limitation of battery capacity of PMVs. Helmet wearing rate was significantly lower in PMV group than in bicycle group, which was associated with relatively low chances to drive long distance on the motorway. In the PMV group, the 'urban helmets' were mainly used, in which the appearance of helmet was priorized, but in the bicycle group, the 'road cycle helmets' were mainly used, in which the light weight or ventilation were priorized. Urban helmets caused stronger pain and more fitting problems than road cycle helmets because the head shapes of Koreans were not properly applied to the helmet design. Since the fitting problem and pain intensity were the important causes that making PMV users not wear the helmets, it is necessary to develop the urban helmets reflecting the head shapes of Koreans in order to increase the helmet wearing rate of the PMV users.

• Journal of Advanced Navigation Technology
• /
• v.24 no.5
• /
• pp.348-357
• /
• 2020

An important challenge in commercialization of eVTOL PAV is to reduce noise for urban air mobility (UAM) operation. Therefore, in this paper, noise priority routes were created to minimize the number of people affected by noise using aviation environmental design tool (AEDT) software and population distribution data for administrative districts, and noise analyses during operation were performed. Also, it was analyzed how much noise exposure could be reduced compared to the number of people affected by noise in the shortest route. Considering that the eVTOL PAV developers do not provide data, the analysis was conducted using a helicopter model. As a result, it was shown that the noise priority route that minimized the amount of noise exposure was more efficient than other routes.

• Journal of Korean Society for Geospatial Information Science
• /
• v.14 no.2 s.36
• /
• pp.77-88
• /
• 2006

Overpopulation has been one of the most serious problem of the Seoul Metropolitan Area (SMA), which consists of the City of Seoul, Incheon, and the whole of Gyeonggi Province. People have been still moving into SMA, especially being concentrated into the fringe of Seoul. This study examines the inner city decline phenomenon of SMA which can be easily found in large cities over the world, based on the demographic data of these area. In addition, this study monitors the imbalance in growing of SMA by analyzing RMI (Rank Mobility Index), and the inverse relation between the self sufficiency of the adjacent area and the commuting rate to Seoul by analyzing commuting data. Even though the total population has been unchanged, the internal change of population was substantial. The growth of Seoul Metro region was placed near the city of Seoul, especially commuter data reassured the population concentrations. The results will be useful in urban planning and growth management.

• Journal of Advanced Navigation Technology
• /
• v.27 no.5
• /
• pp.561-567
• /
• 2023

In this study, the collision risk of the UAM (Urban Air Mobility) corridor was analyzed using a collision risk model applied to the manned aircraft corridor. According to the K-UAM roadmap and operating concept, UAM is expected to fly on a designated route similar to existing manned aircraft operations and operate on two routes, traveling back and forth between the departure point and the destination point. Among domestic manned aircraft routes, the manned aircraft operation between Gimpo Airport and Jeju Airport is similar to this and takes the form of a parallel route with a lateral separation distance between the two routes. In this study, we analyzed the collision risk of the UAM corridor according to the lateral separation distance using a collision risk model used to analyze the collision risk of manned aircraft parallel routes for a similar type of UAM corridor. Based on this, we finally analyzed how many parallel routes could be installed within the width of the Han River, considering the K-UAM demonstration route.

• Journal of Korean Society of Transportation
• /
• v.35 no.3
• /
• pp.183-196
• /
• 2017

In this study, policy evaluation scheme was established to encourage the efficient implementation of EcoMobility which has been expanding gradually all around the world. A total of eight evaluation goals and 22 evaluation items are reviewed and suggested based on the three major evaluation categories of "Basic elements for EcoMobility", "Land use and transport system for EcoMobility", and "Implications and impact of EcoMobility". The results of this study are as follows: the result of AHP analysis which reflects only the hierarchical structure shows a high priority in "Elements for EcoMobility promotion", "Eco-fiendly transport infrastructure", and "Safety in transport". While in result of ANP which considered the elements' dependencies, "Eco-fiendly transport Services", "Welfare in transport", and "Environment by transport" have high weights and importances. In conclusion, this study would be useful to make reasonable judgment based on the analysis results of the two techniques in order to ensure reliability in evaluation of EcoMobility policy. Furthermore we have confirmed appropriate evaluation technique between AHP and ANP which is better to reflect the features of EcoMobility.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.21 no.6
• /
• pp.177-193
• /
• 2022

In the near future, it is expected that the use of autonomous mobility-on-demand services will increase. Considering its complicated service components, including vehicle convenience, driving and matching speed, and platform convenience, the priorities of them will need to be determined for a successful establishment. In this context, this study examined the importance rank of each service component through an online survey of potential users of autonomous mobility-on-demand services. As a result of the AHP (Analytic Hierarchy Process) with respect to the upper-level components, driving and matching speed component is selected as most important, followed by platform convenience and vehicle convenience. Mean rank analysis with respect to lower-level components showed that the in-vehicle congestion level of vehicle convenience, waiting time of driving and matching speed, and pre-booking availability of platform convenience each ranked first. Additional analysis regarding each group was conducted to establish a group-specific strategy. As a result, it would be better to focus on a vehicle than a mobile platform when designing services for the region with a high proportion of the older. Moreover, it is recommended to speed up the driving and matching speeds more than the current public transport, alleviate in-vehicle congestion, and enable the users to book the schedule in advance.

• Journal of the Korean Regional Science Association
• /
• v.36 no.3
• /
• pp.3-16
• /
• 2020

The causes and effects of intra-urban spatial inequality have received much scholarly attention. However, the effects of urban spatial inequality on resident perceptions and the mechanisms through which it is sustained and reproduced remain mostly unknown. This study aimed to investigate whether regional deprivation, the relative socioeconomic standing of a region, affects the residents' perceptions of upward social mobility. By employing the ordinal logistic multilevel model to analyze nested data collected from Seoul, South Korea, this study found that the regional deprivation has a significant negative effect on residents' perception of upward social mobility. The results of this study suggest that one way in which spatial inequality is sustained and reproduced is by the effects of regional deprivation, having negative impacts on the aspirations and socioeconomic activities of residents. This study is expected to provide meaningful implications for planning and policy aimed to combat spatial inequality.

• Journal of Advanced Navigation Technology
• /
• v.28 no.1
• /
• pp.68-76
• /
• 2024

With the recent rapid growth of the domestic and international unmanned aerial vehicle (UAV) market and the increasing importance of UAV operations in urban centers, such as UAMs, the safety management and regulatory framework for human life and property damage caused by UAV failures has been emphasized. In this study, we conducted a comparative analysis of risk-cost models that evaluate the risk of an operating area for safe UAM flight path planning, and identified the main limitations of each model to derive considerations for future model development. By providing a basic model for improving the safety of UAM operations, this study is expected to make an important contribution to technical improvements and policy decisions in the field of UAM flight path planning.

• Proceedings of the KSR Conference
• /
• 2008.06a
• /
• pp.2448-2454
• /
• 2008

Urban areas face congestion problems that diminish personal mobility and freight-transportation productivity. An increasing number of experts suggest that separating freight traffic from passenger traffic makes sense in terms of economics, the environment, and safety. Some experts suggest that underground freight transportation are the solution. The objective of this paper is to review the potential benefits and limitations of freight pipelines as a viable mode of cargo transport that can alleviate congestion on urban highways.