• Title/Summary/Keyword: 최단 접근 거리

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A Robust and Efficient Method to Compute the Closest Approach Distance between Two Ellipsoids (두 타원체 사이의 최단 접근 거리를 구하는 안정적이며 효율적인 방법)

  • Choi, Min Gyu
    • Journal of Korea Game Society
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    • v.19 no.6
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    • pp.99-106
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    • 2019
  • This paper addresses a method to compute the closest approach distance between two ellipsoids in their inter-center direction. This is the key technique for collision detection and response between ellipsoids. We formulate a set of conditions with the inter-center distance, the contact point and the contact normal vector of the two externally-contacting ellipsoids. The equations are solved robustly and efficiently using a hybrid of Newton's method and the bisection method with root bracketing. We demonstrate the robustness and efficiency of the proposed method in various experiments.

On Mathematical Distance on Internal (인터넷 상에서의 수학적 거리)

  • Kang Mi-Yeon;Chung Won-Ho;Kye S. H
    • Proceedings of the Korean Information Science Society Conference
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    • 2005.07a
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    • pp.910-912
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    • 2005
  • 실제 공간에서 네트워크를 통해 지역적으로 산재해 있는 통신 노드들에 관한 최단거리 문제 등을 위시한 각종 지리적 요소를 지니고 있는 문제들을 다루는 것은 복잡할 뿐만 아니라, 환경 및 상태 의존적이라 용이하지 않다고 할 수 있다. 본 논문에서는 네트워크를 통해 존재하는 실제 공간상에서의 지리적 성격의 문제를 특정 공간상의 문제로 매핑하여, 형식화(formalization)함으로써, 그 공간상에서의 수학적 문제로 변환하여 접근할 수 있는 효율적이고 간단한 방법을 제안한다. 그리하여 인터넷상에서의 2 노드 간의 최단 거리 문제를 위한 접근으로서, 본 논문에서 제안된 공간상에서의 두 노드 간의 수학적 거리를 정의하여 정형화된 수학적 최단거리를 구하도록 한다.

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Micro-scale Public Transport Accessibility by Stations - KTX Seoul Station Case Study - (정류장 단위의 미시적 대중교통 접근성 분석 - KTX 서울역 사례연구 -)

  • Choi, Seung U;Jun, Chul Min;Cho, Seong Kil
    • Journal of Korean Society for Geospatial Information Science
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    • v.24 no.1
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    • pp.9-16
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    • 2016
  • As the need of eco-friendly transportation systems for sustainable development increases, public transport accessibility has been considered as an important element of transportation system design. When analyzing the accessibility, shortest path algorithms can be utilized to reflect the actual movement and we can obtain high resolution accessibility for all other stations on the network with shortest distance and time. This study used the algorithm improved by reflecting the penalty of number of transfers and waiting time of overlapped routes to get the accessibility. KTX Seoul Station is a target place and this algorithm is applied to multi-layer subway bus network of Seoul to calculate the accessibility, therefore this study presented the accessibility of KTX Seoul station by stations.

Finding the shortest distance between all pairs of nodes in circular sparse networks by decomposition algorithm (Circular sparse network에서 분할법을 이용한 최단거리 결정)

  • Jun-Hong Kim;Young-Bae Chung
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.26 no.1
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    • pp.47-53
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    • 2003
  • 이 논문은 환(環)을 형성하는 부분네트웍들로 이루어진 sparse network의 특수한 형태에서 최단거리 결정을 위한 효율적인 앨고리즘을 제안한다. 제시된 앨고리즘은 소위 비환(非換) 형태의 sparse network에 대한 최단거리 결정 앨고리즘의 확장이라 할 수 있다. 도우넛 형태를 갖는 sparse network에 대해 최단거리 결정을 위한 접근법으로 하나는 정점제거 방법이고, 다른 하나는 선분제거 방법이다. 여기서 제안된 앨고리즘은 일반적인 n-degree circular sparse network으로 확대될 수 있다.

Network Structures of The Metropolitan Seoul Subway Systems (서울 대도시권 지하철망의 구조적 특성 분석)

  • Park, Jong-Soo;Lee, Keum-Sook
    • Journal of the Economic Geographical Society of Korea
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    • v.11 no.3
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    • pp.459-475
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    • 2008
  • This study analyzes the network structure of the Metropolitan Seoul subway system by applying complex network analysis methods. For the purpose, we construct the Metropolitan Seoul subway system as a network graph, and then calculate various indices introduced in complex network analysis. Structural characteristics of Metropolitan Seoul subway network are discussed by these indices. In particular, this study determines the shortest paths between nodes based on the weighted distance (physical and time distance) as well as topological network distance, since urban travel movements are more sensitive for them. We introduce an accessibility measurement based on the shortest distance both in terms of physical distance and network distance, and then compare the spatial structure between two. Accessibility levels of the system have been getting up overall, and thus the accessibility gaps have been getting lessen between center located subway stops and remote ones during the last 10 years. Passenger traffic volumes are explored from real passenger transaction databases by utilizing data mining techniques, and mapped by GIS. Clear differences reveal between the spatial patterns of real passenger flows and accessibility. That is, passenger flows of the Metropolitan Seoul subway system are related with population distribution and land use around subway stops as well as the accessibility supported by the subway network.

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Development of Integrated Accessibility Measurement Algorithm for the Seoul Metropolitan Public Transportation System (서울 대도시권 대중교통체계의 통합 시간거리 접근성 산출 알고리즘 개발)

  • Park, Jong Soo;Lee, Keumsook
    • Journal of the Korean Regional Science Association
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    • v.33 no.1
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    • pp.29-41
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    • 2017
  • This study proposes an integrated accessibility measurement algorithm, which is applied to the Seoul Metropolitan public transportation system consisting of bus and subway networks, and analyzes the result. We construct a public transportation network graph linking bus-subway networks and take the time distance as the link weight in the graph. We develop a time-distance algorithm to measure the time distance between each pair of transit stations based on the T-card transaction database. The average travel time between nodes has been computed via the shortest-path algorithm applied to the time-distance matrix, which is obtained from the average speed of each transit route in the T-card transaction database. Here the walking time between nodes is also taken into account if walking is involved. The integrated time-distance accessibility of each node in the Seoul Metropolitan public transportation system has been computed from the T-card data of 2013. We make a comparison between the results and those of the bus system and of the subway system, and analyze the spatial patterns. This study is the first attempt to measure the integrated time-distance accessibility for the Seoul Metropolitan public transportation system consisting of 16,277 nodes with 600 bus routes and 16 subway lines.

A Study on the Criteria for Collision Avoidance of Naval Ships for Obstacles in Constant Bearing, Decreasing Range (CBDR) (방위끌림이 없는 장애물에 대한 함정의 충돌회피 기준에 관한 연구)

  • Ha, Jeong-soo;Jeong, Yeon-hwan
    • Journal of Navigation and Port Research
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    • v.43 no.6
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    • pp.377-383
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    • 2019
  • Naval ships that are navigating always have the possibility of colliding, but there is no clear maneuvering procedure for collision avoidance, and there is a tendency to depend entirely on the intuitive judgment of the Officer Of Watch (OOW). In this study, we conducted a questionnaire survey when and how to avoid collision for the OOW in a Constant Bearing, Decreasing Range (CBDR) situation wherein the naval ships encountered obstacles. Using the results of the questionnaire survey, we analyzed the CBDR situation of encountering obstacles, and how to avoid collision in day/night. The most difficult to maneuver areas were Pyeongtaek, Mokpo, and occurred mainly in narrow channels. The frequency appeared on average about once every four hours, and there were more of a large number of ships encountering situations than the 1:1 situation. The method of check of collision course confirmation was more reliable with the eye confirmation results, and priority was given to distance at closest point of approach (DCPA) and time at closest point of approach (TCPA). There was not a difference in DCPA between the give-way ship and stand-on ship, but a difference between day and night. Also, most navigators prefer to use maneuvering & shifting when avoiding collisions, and steering is 10-15°, shifting ±5knots, and the drift course was direction added stern of the obstacles to the direction of it. These results will facilitate in providing officers with standards for collision avoidance, and also apply to the development of AI and big data based unmanned ship collision avoidance algorithms.

Time-distance Accessibility Computation of Seoul Bus System based on the T-card Transaction Big Databases (교통카드 빅데이터 기반의 서울 버스 교통망 시간거리 접근성 산출)

  • Park, Jong Soo;Lee, Keumsook
    • Journal of the Economic Geographical Society of Korea
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    • v.18 no.4
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    • pp.539-555
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    • 2015
  • This study proposes the methodology for measuring the time-distance accessibility on the Seoul bus system based on the T-card transaction databases and analyzes the results. T-card transaction databases contain the time/space information of each passenger's locations and times of the departure, transfers, and destination. We introduce the bus network graph and develop the algorithms for time-distance accessibility measurement. We account the average speed based on each passenger's get-in and getoff information in the T-card data as well as the average transfer time from the trip chain transactions. Employing the modified Floyd APSP algorithm, the shortest time distance between each pair of bus stops has been accounted. The graph-theoretic nodal accessibility has been given by the sum of the inverse time distance to all other nodes on the network. The results and spatial patterns are analyzed. This study is the first attempt to measure the time-distance accessibility for such a large transport network as the Seoul bus system consists of 34,934 bus stops on the 600 bus routes, and each bus route can have different properties in terms of speed limit, number of lanes, and traffic signal systems, and thus has great significance in the accessibility measurement studies.

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GIS Optimization for Bigdata Analysis and AI Applying (Bigdata 분석과 인공지능 적용한 GIS 최적화 연구)

  • Kwak, Eun-young;Park, Dea-woo
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2022.05a
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    • pp.171-173
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    • 2022
  • The 4th industrial revolution technology is developing people's lives more efficiently. GIS provided on the Internet services such as traffic information and time information makes people getting more quickly to destination. National geographic information service(NGIS) and each local government are making basic data to investigate SOC accessibility for analyzing optimal point. To construct the shortest distance, the accessibility from the starting point to the arrival point is analyzed. Applying road network map, the starting point and the ending point, the shortest distance, the optimal accessibility is calculated by using Dijkstra algorithm. The analysis information from multiple starting points to multiple destinations was required more than 3 steps of manual analysis to decide the position for the optimal point, within about 0.1% error. It took more time to process the many-to-many (M×N) calculation, requiring at least 32G memory specification of the computer. If an optimal proximity analysis service is provided at a desired location more versatile, it is possible to efficiently analyze locations that are vulnerable to business start-up and living facilities access, and facility selection for the public.

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A Study on Improvement of Gravity model Decay Function of Transporting Demand Forecasting Considering Space Syntax (Space Syntax를 이용한 교통수요예측의 중력모형 저항함수의 개선방안)

  • Jang, Jin-Young
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.3
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    • pp.617-631
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    • 2019
  • In the four-step demand model, a gravity mode is used most commonly at the trip distribution stage. The purpose of this study was to develop a new friction factor that can express the accessibility property as a single friction factor to compensate for the variable limits of the gravity model parameters (travel time, travel cost). To derive a new friction factor, a new friction factor was derived using the space syntax that can quantify the characteristics of the urban space structure, deriving the link-unit integration degree and then using the travel time and travel distance relationship. Calibration of the derived friction factor resulted in a similar level to that of the existing friction factor. As a result of verifying the various indicators, the explanatory power was found to be excellent in the short - and long - distance range. Therefore, it is possible to derive and apply the new friction factor using the integration index, which can complement the accessibility beyond the limit of the existing shortest distance, and it is believed to be more advantageous in future utilization.