• Journal of Positioning, Navigation, and Timing
• /
• v.11 no.2
• /
• pp.99-107
• /
• 2022

Urban Air Mobility (UAM) such as a drone taxi is one of the future transportations that have recently been attracting attention. Along with the construction of an urban terminal, an accurate landing system for UAM is also essential. However, in urban environments, reliable Global Navigation Satellite Systems (GNSS) signals cannot be received due to obstacles such as high-rise buildings which causes multipath and non-line of sight signal. Thus, the positioning result in urban environments from the GNSS signal is unreliable. Consequently, we propose the Ultra-Wideband (UWB) network to assist the soft landing of UAM on a vertiport. Since the positioning performance of UWB network depends on the layout of UWB anchors, it is necessary to optimize the layout of UWB anchors. In this paper, we propose a two-steps genetic algorithm that consists of binary genetic algorithm involved multi objectives fitness function and integer genetic algorithm involved robust solution searching fitness function in order to optimize taking into account Fresnel hole effects.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.47 no.2
• /
• pp.28-48
• /
• 2019

This research is aimed at identifying the perception associated with urban regeneration and predicting policy implications of future directions by analyzing the trend of urban regeneration depicted in the mass media by utilizing SNA (Semantic-Network Analysis) techniques. As the number of articles has increased, it is noted through analysis that the interrelationships between social phenomena and issues have combined to form the meaning of urban regeneration. Overall, 'urban' and 'regeneration' keywords also appeared at different periods, with 'urban' closely related to 'regeneration' starting in 1970 when urbanization was becoming more prevalent. It was analyzed that the frequency of 'urban' appeared more frequently in the early 1990s, while the frequency of 'rural' decreased sharply. Until the 1990s, the slums and the recession that appeared as side effects of urban problem-solving policies were mostly concentrated in cities. Policy discussions were conducted with the goal of improving the physical environment of cities rather than concentrating on the surrounding rural areas. The distributions of the keywords 'development' and 'regeneration' have increased quantitatively since the 1970s, and urban polarization has exploded due to the development of the external growth of cities, mirroring the trend of accelerated environmental threats. In particular, the keywords for 'regeneration' emerged mainly related to environmental problems, which led to the need for urban regeneration, and environmentally and ecologically friendly development. The emergence of "urban," "regeneration" and "environment" as keywords having to do with urban regeneration grew in the 1990s. This suggests that urban regeneration is now linked to "environment", as that has become a social issue.

• Proceedings of the KOR-KST Conference
• /
• 1995.12a
• /
• pp.22-42
• /
• 1995

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38A no.12
• /
• pp.1054-1060
• /
• 2013

This paper proposes a vehicle ad-hoc network (VANET) routing algorithm to reduce the probability of routing path discontinuity in urban intersections. In urban intersections, the vehicles may frequently change their moving directions. It can cause the disconnection of routing path and the increase of a packet transmission delay. In order to resolve this problem, the proposed routing algorithm exploits the information of moving directions in urban intersections. In this way, the proposed algorithm can reduce the probability of the local maximum which causes the increase of the number of routing hops and packet transmission delay. Simulation results show that the proposed algorithm can reduce the local maximum probability by 10% and increase the successful packet transmission ratio by 5% compared to the conventional VANET routing algorithms.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.19 no.6
• /
• pp.766-772
• /
• 2009

Generally, wind industry has been oriented to large power systems which require large windy areas and often need to overcome environment restrictions. However, small-scale wind turbines are closer to the consumers and have a large market potential, and much more efforts are required to become economically attractive. In this paper, a prototype of a small-scale urban wind generation system for battery charging application is described and a neural network based MPPT(Maximum Power Point Tracking) algorithm which can be effectively applied to urban wind turbine system is proposed. Through Matlab based simulation studies and actual implementation of the proposed algorithm, the feasibility of the proposed scheme is verified.

• Journal of Electrical Engineering and Technology
• /
• v.8 no.4
• /
• pp.889-898
• /
• 2013

The shortest-path searching algorithm must not only find a global solution to the destination, but also solve a turn penalty problem (TPP) in an urban road transportation network (URTN). Although the Dijkstra algorithm (DA) as a representative node-based algorithm secures a global solution to the shortest path search (SPS) in the URTN by visiting all the possible paths to the destination, the DA does not solve the TPP and the slow execution speed problem (SEP) because it must search for the temporary minimum cost node. Potts and Oliver solved the TPP by modifying the visiting unit from a node to the link type of a tree-building algorithm like the DA. The Multi Tree Building Algorithm (MTBA), classified as a representative Link Based Algorithm (LBA), does not extricate the SEP because the MTBA must search many of the origin and destination links as well as the candidate links in order to find the SPS. In this paper, we propose a new Link-Based Single Tree Building Algorithm in order to reduce the SEP of the MTBA by applying the breaking rule to the LBA and also prove its usefulness by comparing the proposed with other algorithms such as the node-based DA and the link-based MTBA for the error rates and execution speeds.

• Journal of architectural history
• /
• v.12 no.3
• /
• pp.65-86
• /
• 2003

After 1960s, a radical change was taken place in the modern urban theories which were developped by many architects and planners like Ebenezer Howard, Tony Garnier, Le Corbusier, Ludwig Hiberseimer, and Patrick Abercrombie. Many contemporary architects like Kevin Lynch, Aldo Rossi, Christopher Alexander, Colin Rowe, Rem Koolhaas, and Bernard Tschumi have a view that modern urban theories lost their abilities to organize and control new realities so that new urban theories was needed in order to cope with urban problems in the 1960s. In this study, we are to examine contemporary urban theories in comparison with modern urban theories and to clarify the role of discourse of language in its emergence. In consequence we can detect four main themes in the process of transformation from modern urban theories to contemporary urban theories : from functionalism to formalism, from historicism to archeology, from space to placeness, and from hierarchical organization to network. And we can prove that such themes basically depend on the discourse of language.

• International Journal of Computer Science & Network Security
• /
• v.22 no.3
• /
• pp.9-16
• /
• 2022

The relevance of the topic is determined by the existence of inconsistencies between economic and environmental aspects of innovative development of urban logistics infrastructure, as well as the conflict of public, state and private commercial interests in this issue. The purpose of the article is to determine the principles and effective tools for innovative development of urban logistics infrastructure, taking into account pandemic constraints. The influence of the environmental aspect on the dynamics of transport flows was analyzed in detail and characterized, the scheme of determining the optimal solution for the development of the city was proposed considering the compromise between economic and ecological interests of society, state and business entities. A scheme of innovative development of urban logistics infrastructure under pandemic constraints was also developed. Materials of the article are relevant for developers of city plans, managers of urban logistics infrastructure, employees of enterprises participating in transport and logistics markets, scientists, and doctoral students.

• Proceedings of the KSR Conference
• /
• 2009.05a
• /
• pp.132-140
• /
• 2009

The Cradle(R) is specialized systems engineering tool that developed by 3SL(Structure Software System Limited) that has headquarters in U.K. and U.S.A.. It is recognized as the fastest growing Computer-Aided Systems Engineering Tool(CASE Tool). We built up requirements management database by using Cradle(R) on urban maglev program in Korea. So Cradle(R) provide a network function, is available accesses of clients in external organization that is associated on urban maglev program by the internet. However the network function of Cradle(R) require an opening of some a specific network ports and may causes a decreasing network speed. In this paper, we propose the method to establish an user environment of a requirements management database that overcome constraints on network condition.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.36 no.5
• /
• pp.335-341
• /
• 2018

The KDE (Kernel Density Estimation) technique in GIS (Geographic Information System) has been widely used as a method for determining whether a phenomenon occurring in space forms clusters. Most human-generated events such as traffic accidents and retail stores are distributed according to a road network. Even if events on forward and rear roads have short Euclidean distances, network distances may increase and the correlation between them may be low. Therefore, the NKDE (Network-based KDE) technique has been proposed and applied to the urban space where a road network has been developed. KDE is being studied in the field of business GIS, but there is a limit to the microscopic analysis of economic activity along a road. In this study, the NKDE technique is applied to the analysis of urban phenomena such as the density of shops rather than traffic accidents that occur on roads. The results of the NKDE technique are also compared to pedestrian networks and road centerline networks. The results show that applying NKDE to microscopic trade area analysis can yield relatively accurate results. In addition, it was found that pedestrian network data that can consider the movement of actual pedestrians are necessary for accurate trade area analysis using NKDE.