• Journal of Advanced Navigation Technology
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• v.27 no.1
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• pp.77-95
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• 2023

In this study, the conceptual design of a tilt + stopped rotor type electric vertical take-off and landing (eVTOL) aircraft was performed using design iteration. Based on Hyundai Motor's S-A1, the mission profile was defined using the concept of urban air mobility (UAM), and configuration design and aerodynamic analysis were performed using OpenVSP and XFLR5 software. After estimating the required power for the designed eVTOL, the required performance of the battery and the maximum take-off weight (MTOW) were calculated. . It was iteratively calculated using Microsoft Excel and Visual Basic Application, and a new electric motor weight estimation formula was derived. Also, the sensitivity analyses of each design variables of an eVTOL was performed using the automated program.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.30 no.1
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• pp.20-27
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• 2022

It is anticipated that there will be radical disputes over land ownership in the event of the advent of the era of UAM. As such, policy alternative is presented by analyzing and researching relevant laws at home and abroad on the means of legislating 'Regulations on compensation for use of air space above land' in preparation of such occurrence. As the results of the study, it is deemed to limit the range of the land ownership in accordance with UAM operation as follows. First, it is proposed to newly enact regulation to limit the ownership of air space of land owner to the public space above the elevation of 200m as stipulated under the Article 78 of the Aviation Safety Act. Second, as the result of analysis made for the option of making compensation from the perspective of the property right of land ownership and option of not making compensation from the perspectives of public interest and concerns in the event of operation of UAM within the air space below the elevation of 200m, it is deemed that legislative decision is necessary through more extensive studies in the future.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.8
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• pp.583-590
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• 2022

This paper presents a framework, MADAM(Multidisciplinary Analysis and Design for Advanced Mobility). For the actual UAM operation, not only aircraft performances but also demand, cost and flight scenarios are in connection; the overall framework is essential for the multidisciplinary design. In this study, the framework is developed and introduced. Demand and cost analysis of Gimpo-Samseong line in the Seoul area using the framework is conducted as an example result. Also, future ticket prices are estimated by applying changes in the aspects of major cost components and the price, ￦76,000, is calculated with the target for maximizing the total profit in the year 2035.

• Journal of the Korea Society of Computer and Information
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• v.28 no.2
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• pp.131-142
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• 2023

In this paper, we propose a new station selection algorithm to solve the illegal parking problem of shared electric scooters and improve the service quality. Recently, as a solution to the urban transportation problem, shared electric scooters are attracting attention as the first and last mile means between public transportation and final destinations. As a result, the shared electric scooter market grew rapidly, problems caused by electric scooters are becoming serious. Therefore, in this study, text data are collected to understand the nature of the problem, and the problems related to shared scooters are viewed from the perspective of pedestrians and users in 'LDA Topic Modeling', and a station extension algorithm is based on this. Some parking lots have already been installed, but the existing parking lot location is different from the actual area of tow. Therefore, in this study, we propose an algorithm that can install stations at high actual tow density using mixed clustering technology using K-means after primary clustering by DBSCAN, reflecting the 'current state of electric scooter tow in Seoul'.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.12
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• pp.819-828
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• 2022

Sensitivity of aircraft sizing depending on battery performance was studied for a generic quad tilt rotor type electric vertical takeoff and landing vehicle. The mission requirements proposed by Uber Elevate and NASA were used for initial sizing, and the calculated gross weight is ranged between 5,000lb and 11,000lb for battery specific energy range of 200-400Wh/kg in pack level and continuous discharge rate range of 4-5C. For the assumed gross weight of 7,000lb, the required battery performance was calculated with two different criteria: available power and energy, and the effects of battery specific energy and discharge rate are analyzed. The maximum discharge rate is also recommended considering failure cases such as one battery pack inoperative and one prop rotor inoperative.

• Journal of Aerospace System Engineering
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• v.16 no.3
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• pp.42-51
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• 2022

An eVTOL aircraft, which is required to operate with low pollution/low noise in urban environments, mostly use battery-powered electric propulsion systems as power sources, not traditional propulsion systems such as reciprocating or turbine engines. Accordingly, certification preparation for the electric propulsion system and securing the safety of the electric propulsion system, are important issues. In the U.S., special technical standards equivalent to FAR Part 33 were issued to certify electric engines, and in Europe, various special conditions were established to certify electric propulsion systems. Thus, in Korea, the technical standards for the electric propulsion system for eVTOL aircraft must also be prepared in line with the U.S. and Europe. In this paper, SC E-19, the technical standard of the electric/hybrid propulsion system (EHPS) in special conditions, was analyzed. Additionally, securing the safety of the electric propulsion system of the aircraft are proposed, through the collaboration of SC E-19 technical standards with the existing aircraft safety evaluation procedure ARP 4761. Finally, through a case study of the Ehang 184 electric propulsion system, it has been confirmed that the proposed safety assurance method is applicable at the aircraft level.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.6
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• pp.124-140
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• 2023

The rapid growth in shared E-scooters worldwide has led to many studies on the topic. The results of these studies are still in the early stages, and the main factors affecting trips are being identified. In particular, the development of trip-generation models is very important for transportation planning, and a new transportation mode for developing the models for shared E-scooters is lacking both domestically and internationally. This study aims to develop a trip generation model for shared E-scooters using significant variables by thoroughly reviewing previous studies. The trip characteristics of major service areas and other areas may differ owing to the trip characteristics of the mode. The trip generation models were developed based on the service trip density by dividing the areas by service level. The factors affecting shared E-scooter trips in major service areas included the presence of universities, closeness centrality, and cultural areas, while factors affecting the trips in minor service areas included the presence of universities, betweenness centrality, and trip distance. The developed models provide basic information that can be used to establish transport policies for introducing shared E-scooters in cities in the future.

• Journal of Aerospace System Engineering
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• v.17 no.2
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• pp.26-37
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• 2023

Urban air mobility (UAM) is being developed as part of the next-generation aircraft, which could be a viable solution to entrenched problems of urban traffic congestion and environmental pollution. A new airport platform called vertiport as a space where UAM can take off and land vertically is also being introduced. Noise regulations for UAM will be strict due to its operation in a highly populated urban area. Ground effects caused by vertiport can directly affect aerodynamic forces and noise characteristics of UAM. In this study, ground effects of vertiport on aerodynamic loads, vorticity field, and far-field noise were analyzed using Lattice-Boltzmann Method (LBM) simulation and Ffowcs Williams and Hawkings (FW-H) acoustic analogy with a permeable surface method.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.5
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• pp.28-41
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• 2022

A road system with CV(Connected Vehicle)s, which is often referred to as a cooperative intelligent transportation system (C-ITS), provides various road information to drivers using an in-vehicle warning system. Road environments with CVs induce drivers to reduce their speed or change lanes to avoid potential risks downstream. Such avoidance maneuvers can be considered to improve driving behaviors from a traffic safety point of view. Thus, empirically evaluating how a given in-vehicle warning information affects driving behaviors, and monitoring of the correlation between them are essential tasks for traffic operators. To quantitatively evaluate the effect of in-vehicle warning information, this study develops a method to calculate compliance rate of drivers where two groups of speed profile before and after road information is provided are compared. In addition, conventional indexes (e.g., jerk and acceleration noise) to measure comfort of passengers are examined. Empirical tests are conducted by using PVD (Probe Vehicle Data) and DTG (Digital Tacho Graph) data to verify the individual effects of warning information based on C-ITS constructed in Seoul metropolitan area in South Korea. The results in this study shows that drivers tend to decelerate their speed as a response to the in-vehicle warning information. Meanwhile, the in-vehicle warning information helps drivers to improve the safety and comport of passengers.