• Journal of Positioning, Navigation, and Timing
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• 제11권2호
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• pp.99-107
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• 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.

• 한국조경학회지
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• 제47권2호
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• pp.28-48
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• 2019

본 연구는 1920~1999년까지 매스미디어에 나타난 국내 도시재생의 시대적 동향을 의미연결망(Semantic-Network Analysis)분석방법을 활용하여 도시재생에 대한 인식을 파악하고, 향후 지향해야 할 정책적 시사점을 예견하는데 목적이 있다. 분석 결과, 시대별로 기사수가 증가함에 따라 사회적 현상과 이슈의 상호관계가 복잡하게 얽혀서 도시재생의 의미가 형성되어 온 것으로 분석되었다. 전반적으로 '도시'와 '재생' 키워드도 시대별로 등장 빈출이 다르게 나타났는데, 특히 도시개발이 심화되는 1970년을 기점으로 '도시'와 '재생'이 밀접하게 관련되어 나타나는 것으로 분석되었다. 시대적 변천에 따라 '도시'는 1990년도에 이를수록 등장빈도가 높게 나타났으나, '농촌'의 등장빈도가 급격히 하향하는 것으로 분석되었다. 이는 1990년대까지의 도시문제 해결 정책의 부작용으로 나타난 슬럼화 및 침체 현상이 대부분 도시에 집적되어 있었으며, 재생에 있어서 농촌보다 도시의 물리적 환경을 개선하는 목표 중심으로 정책적 논의가 진행되었기 때문으로 해석된다. 1970년대 이후 '개발'과 '재생'의 키워드 분포가 양적 증가 추세를 보이는데, 도시의 외연적 성장을 위한 개발로 인해 도시의 양극화 현상은 두드러지게 나타나 결국 환경적 위협의 가속화를 초래했던 시대적 상황과 인식이 같은 흐름을 보이는 것으로 나타났다. 특히 '재생'의 키워드는 주로 환경문제와 직결되는 쓰레기, 폐품, 오염, 공해 등과 같은 키워드와 연관되어 등장하였는데, 이러한 환경문제의 대두는 1980년대 이후 지속가능성에 대한 관심, 환경 및 생태 친화적 기술과 분야의 발전을 촉진시키는 계기가 되었다. 도시재생과 관련하여 허브 역할을 수행하는 키워드로 '도시', '재생', '환경'의 등장 빈출이 1990년대에 이를수록 증가하는 것으로 나타났는데, 이는 도시재생의 촉발이 사회문제로 제기되었던 '환경'과 밀접한 관계가 있음을 시사한다.

• 대한교통학회:학술대회논문집
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• 대한교통학회 1995년도 제28회 학술발표회
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• pp.22-42
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• 1995

• 한국통신학회논문지
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• 제38A권12호
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• pp.1054-1060
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• 2013

본 논문에서는 도심 교차로에서 경로 이탈 확률을 낮추어 줄 수 있는 차량 통신용 라우팅 알고리즘을 제안한다. 차량이 밀집된 도심의 교차로 지역에서는 차량들의 방향 전환으로 잦은 네트워크 단절과 패킷 전송지연 문제를 발생 시킬 수 있다. 본 논문에서는 이러한 문제점을 개선하기 위해 전송 노드 선정 과정에서 같은 진행방향의 노드를 이웃 노드로 선정하여 교차로에서 네트워크 단절의 비율을 낮출 수 있는 VANET (Vehicular Ad-hoc Network)용 라우팅 알고리즘을 제안한다. 시뮬레이션을 통한 성능분석 결과는 제안하는 알고리즘이 기존 라우팅 알고리즘에 비해 도심 교차로에서 경로 이탈 확률을 약 10% 감소시키며 네트워크 단절 비율을 5% 감소시킴을 보인다.

• 한국지능시스템학회논문지
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• 제19권6호
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• pp.766-772
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• 2009

일반적으로 풍력발전은 광범위한 영역에 지속적인 바람을 요구하는 대형 시스템 위주로 개발이 되어왔다. 그러나 소형 풍력발전 시스템은 사용자에게 보다 친숙하고, 대형에 비해 보다 광범위한 적용이 가능하다는 점 때문에 최근 이에 대한 관심이 증가되고 있는 실정이다. 이에 본 연구에서는 배터리 충전에 효과적으로 도입될 수 있는 도시형 풍력발전을 위한 프로토타입 시스템에 대해 기술하며, 프로토타입 시스템에 효과적으로 도입될 수 있는 인공신경망 기반의 최대 전력점 추종 알고리즘을 제안하고자 한다. 또한 Matlab기반의 다양한 시뮬레이션 및 실제 시스템 설계를 통해 제안된 기법의 유용성을 확인하고자 한다.

• Journal of Electrical Engineering and Technology
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• 제8권4호
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• pp.889-898
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• 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.

• 건축역사연구
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• 제12권3호
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• pp.65-86
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• 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
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• 제22권3호
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• pp.9-16
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• 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.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.132-140
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• 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.

• 한국측량학회지
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• 제36권5호
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• pp.335-341
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• 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.