• Journal of the Korean Institute of Intelligent Systems
• /
• v.13 no.3
• /
• pp.342-347
• /
• 2003

It is essential to develop an algorithm for the estimate of link travel velocity and for the supply and control of travel information in the context of intelligent transportation information system. The paper proposes the fuzzy logic based prediction of link travel velocity. Three factors such as time, date and velocity are considered as major components to represent the travel situation. In the fuzzy modeling, those factors were expressed by fuzzy membership functions. We acquire position／velocity data through GPS antenna with PDA embedded probe vehicles. The link travel velocity is calculated using refined GPS data and the prediction results are compared with actual data for its accuracy.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.18 no.5
• /
• pp.142-155
• /
• 2019

This study was conducted with the aim of developing a system to collect taxi GPS probe information to prevent link defects and to improve the accuracy of the standard link-based travel speed by determining when to go into and come out the link. For this purpose, a framework and algorithm consisting of a five-step process for standard link-based map matching and individual vehicle travel speed are presented and used it to calculate the average travel speed of the service link. Two on-site surveys of Teheran and Hakdong-ro were conducted to verify the results by the methods proposed in this paper. On the basis of the overall time of the field survey, the deviation in the travel speed was 0.2 km/h and 0.6 km/h, the accuracy was 99% and 96%, and the MAPE(Mean Absolute Percentage Error) was 1% and 4% in Teheran and Hakdong-ro, respectively. These results were more accurate thand those obtained using conventional methodologies without standard links.

• Journal of Korean Society of Transportation
• /
• v.16 no.2
• /
• pp.197-207
• /
• 1998

지능형교통체계(ITS)환경 하에서 요구되는 정보서비스의 기본적인 형태는 통행속도, 지체정도, 통행시간등으로 대별 되어질 수 있다. 그 중 통행시간의 기본적 요소로서 링크통행시간을 산출하기 위한 제반 기법을 소개하였고, 특히 GPS를 이용한 링크통행시간 산정기법을 본 고에서는 제시하였다. 현재 GPS를 장착한 차량이 고유의 목적 (예를 들면, 위치파악 및 배차등의 목적으로)을 위해서 점차 늘어나고 있는 추세인 만큼 (개인택시조합등) 이러한 자원을 부수적으로 이용할 수 없는지에 대한 활용방안의 여부가 논문을 작성하는 계기가 되었다. 이를 위해서 본 고에서는 구체적으로 GPS 원시테이터, 수치도로지도 (GIS포함) 및 무선데이터망을 이용하여 링크 통행시간을 산출하는 기법이 이를 위해서 본 고에서는 구체적으로 제시되었으며, 이들을 통한 교통정보의 수집 가능성을 제안하였다. 중간 결과로서 실제 가로주행조사를 통해서 얻어진 링크통행시간과 본 연구에서 게시된 GPS를 통해 얻어진 링크통행시간과 비교해 보면 오창의 범위가 10%내외로서 판명되어 그나마 동적교통정보 수집조건이 열악한 우리실정에 큰 자원이 될 수 있다는 확신을 얻을 수 ? 있었다. 한편, 본 연구에서 수행되지 못하였으나 추가연구로서 반드시 수행되었으면 하는 몇가지의 항목이 결론부에 함께 제시되었다.

• Journal of Korean Society of Transportation
• /
• v.18 no.5
• /
• pp.57-67
• /
• 2000

Two fuzzy travel time estimators for interrupted traffic flow were developed based on field survey data and simulation data 7hat is collected from DETSIM, which is microscopic traffic simulation model that car-following theory is applied. One is FETTOS(Fuzzy Estimator of Travel Time using Occupancy and Spot speed) and the other is FETTOS(Fuzzy Estimator of Travel Speed using Volume and Occupancy). Fuzzy logic controller was applied to the estimators to deal with non-linear relationship between traffic variables and travel time. According to results of simulation and field survey. estimation of travel time can be modeled by using percent occupancy better than any other traffic variables. Detector location from storyline and signal timing Plan of intersection are affected to estimate travel time. With a few findings, the estimator was constructed and its performance was tested for observed travel time data and simulated data. FETTOS which needs signal timing plan and detector location estimates travel time with accurate better than FETSVO does. However. FETSVO has excellent transferability because the estimator needs set of input data only; volume and time mean speed.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
• /
• 2008.10a
• /
• pp.177-181
• /
• 2008

본 논문은 제주 택시 텔레매틱스 시스템의 운영과정에서 축적되고 있는 각 택시들의 이동이력 데이터를 기반으로 관심구간의 통행속도에 관련된 필드들을 효율적으로 추출하는 기법을 설계하고 구현한다. 구현된 인터페이스는 도로네트워크 상에서 관심구간의 양끝점을 입력받아 $A^*$ 알고리즘을 수행하여 경로상에 포함된 각 링크를 결정한 후 해당 링크 아이디를 포함하는 질의문의 스켈리튼을 생성한다. 이 질의문을 수정하여 관심구간의 속도 레코드수, 속도 평균, 승객탑승시의 속도, 요일별 시간대별 평균 속도 등 다양한 정보를 체계적으로 검색할 수 있다. 제주시 연삼로 구간에 대한 시험적 검색 결과는 승객이 탑승한 경우 전체 경우 보다 $30{\sim}50%$ 정도의 보고수, $2{\sim}4$ kmh 빠른 통행 속도 등을 보이고 있으며 시간대별 통계는 요일별 통행속도 패턴의 변화를 정량화하고 있다.

• Journal of Korean Society of Transportation
• /
• v.23 no.8 s.86
• /
• pp.171-179
• /
• 2005

This paper presents the algorithm using fuzzy inference that preestimates each link speed changed by different kinds of road situations. The elements we are considered are time zone, rainfall probability information and lane control information. This paper is consists of three parts. First of all we set up the fuzzy variables, and preestimate link speed changed by various road situations. For this process, we build the membership functions for each fuzzy variable and establish the fuzzy inference relations to find how fuzzy variables influence on link speed. Second, using backtracking method, we search the shortest route influenced by link speed changed by fuzzy inference. Third, we apply this algorithm to hypothetical network and find the shortest path. As a result, it is shown that this algorithm choose appropriate roundabout path according to the changing road situations.

• Information and Communications Magazine
• /
• v.21 no.5
• /
• pp.70-79
• /
• 2004

최적 경로 서비스를 제공하기 위해서는 구간 통행속도, 구간 통행시간, 회전 정보, 혼잡도 등과 같은 교통정보가 필요하다. 또한, 고객에게 신뢰성 있는 최적 경로를 제공하기 위해서는 실시간 교통정보 수집은 반드시 필요하며, 이러한 실시간 교통정보 수집 방법들에 대한 고찰과 검토가 선행되어야 한다. 기존의 교통정보 수집방법을 살펴보면 지점검지 방식의 경우, 수집되는 정보가 검지기 설치 지점의 지점속도(Spot Speed)이므로 해당 링크를 주행한 통행속도(통행시간)의 대표값으로 채택하기에는 다소 무리가 있으며 구간검지 방식의 경우, 일반적으로 급격한 교통류 변동에 따른 대기행렬 검지가 늦다는 단점이 있다.(중략)

• The Journal of the Korea institute of electronic communication sciences
• /
• v.9 no.12
• /
• pp.1373-1380
• /
• 2014

In order to calculate accurate traffic and traffic speed, qualified and sufficient GPS data should be provided. However, it is difficult to provide accurate traffic information using restricted GPS data from probe vehicles because of communication costs. This paper developed a algorithm that recovers links omitted by restricted GPS data with topology information, and calculate traffic speed with original links and recovered links. T traffic information service of city with a new algorithm can provide more accurate traffic and traffic speed than the original system.

• Journal of Korean Society of Transportation
• /
• v.23 no.8 s.86
• /
• pp.113-128
• /
• 2005

We propose a modified version of 'a Lazy Version of Eppstein's k shortest paths Algorithm(LVEA)' which can find the k shortest paths in total time O(m+ n log n+ K log K) in the worst-case. The algorithm we propose, since the Link repeated paths are all eliminated when enumerating k shortest paths, is No link repeated paths algorithm that is suitable in a transportation network.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.10 no.6
• /
• pp.63-73
• /
• 2011

Travel speed is an important parameter for measuring road traffic. UTIS(Urban Traffic Information System) was developed as a mobile detector for measuring link travel speeds in South Korea. After investigation, we founded that UTIS includes some missing data caused by the lack of probe vehicles on road segments, system failures and etc. Imputation is the practice of filling in missing data with estimated values. In this paper, we suggests a new model for imputing missing data to provide accurate link travel speeds to the public. In the field test, new model showed the travel speed measuring accuracy of 93.6%. Therefore, it can be concluded that the proposed model significantly improves travel speed measuring accuracy.