• Journal of Korean Society of Transportation
• /
• v.22 no.6
• /
• pp.109-120
• /
• 2004

Since the late of 1990, there have been number of studies on the required number of probe vehicles and/or optimal aggregation interval sizes for travel time estimation and forecasting. However, in general one to five minutes are used as aggregation intervals for the travel time estimation intervals for the travel time estimation and/or forecasting of loop detector system without a reasonable validation. The objective of this study is to deveop models for identifying optimal aggregation interval sizes of loop detector data for travel time estimation and prediction. This study developed Cross Valiated Mean Square Error (CVMSE) model for the link and route travel time forecasting, The developed models were applied to the loop detector data of Kyeongbu expressway. It was found that the optimal aggregation sizes for the travel time estimation and forecasting are three to five minutes and ten to twenty minutes, respectively.

• Journal of Korean Society of Transportation
• /
• v.18 no.3
• /
• pp.55-76
• /
• 2000

We propose a general solution methodology for identifying the optimal aggregation interval sizes as a function of the traffic dynamics and frequency of observations for four cases : i) link travel time estimation, ii) corridor/route travel time estimation, iii) link travel time forecasting. and iv) corridor/route travel time forecasting. We first develop statistical models which define Mean Square Error (MSE) for four different cases and interpret the models from a traffic flow perspective. The emphasis is on i) the tradeoff between the Precision and bias, 2) the difference between estimation and forecasting, and 3) the implication of the correlation between links on the corridor/route travel time estimation and forecasting, We then demonstrate the Proposed models to the real-world travel time data from Houston, Texas which were collected as Part of the Automatic Vehicle Identification (AVI) system of the Houston Transtar system. The best aggregation interval sizes for the link travel time estimation and forecasting were different and the function of the traffic dynamics. For the best aggregation interval sizes for the corridor/route travel time estimation and forecasting, the covariance between links had an important effect.

• 한국ITS학회:학술대회논문집
• /
• v.2006 no.10
• /
• pp.50-55
• /
• 2006

• Proceedings of the KOR-KST Conference
• /
• 1999.10a
• /
• pp.440-445
• /
• 1999

• Journal of the Korea Society of Computer and Information
• /
• v.15 no.5
• /
• pp.133-141
• /
• 2010

Contents adaptation is a technology which converts one content to another content used in various devices. Specially, synchronization of inter-media which are included in a document is needed. There are various proposals and solutions for synchronization of inter-media. In the paper, I present "TATS : Temporal Aggregate Tree Strategy" model, which is used for specifying the temporal relationship among media in series of time. In the TATS model, aggregate tree, a sort of a binary tree, is generated from the execution time of those media. Using this aggregate tree, I implemented the inter-media synchronizations.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.18 no.1
• /
• pp.56-73
• /
• 2019

Probe-based systems have been gaining popularity in advanced traveler information systems. However, the high possibility of providing inaccurate travel-time information due to the inherent time-lag phenomenon is still an important issue to be resolved. To mitigate the time-lag problem, different prediction techniques have been applied, but the techniques are generally regarded as less effective for travel times with high variability. For this reason, current 5-min aggregated data have been commonly used for real-time travel-time provision on highways with high travel-time fluctuation. However, the 5-min aggregation interval itself can further increase the time-lags in the real-time travel-time information equivalent to 5 minutes. In this study, a new scheme that uses both individual probe and 5-min aggregated travel times is suggested to provide reliable real-time travel-time information. The scheme utilizes individual probe data under congested conditions and 5-min aggregated data under uncongested conditions, respectively. As a result of an evaluation with field data, the proposed scheme showed the best performance, with a maximum reduction in travel-time error of 18%.

• Proceedings of the Korean Information Science Society Conference
• /
• 1998.10b
• /
• pp.389-391
• /
• 1998

데이터 웨어하우스에서는 시간에 따라 변화되는 데이터를 관리함으로써 좀더 정확하게 요약화된 정보를 제공할 수 있다. 거의 모든 데이터 웨어하우스는 원시 데이터로 관계형 데이터베이스를 사용하지만, 관계형 데이터베이스는 시간 데이터에 대해 실제적인 지원을 하지 않는다. 그러므로 시간 변이 데이터에 대한 정확한 정보를 얻기가 어렵다. 본 논문에서는 이러한 시간 변이 데이터의 지원이 가능한 시간지원 데이터 웨어하우스를 설계하고자 한다. 이를 위해, 기존의 데이터 웨어하우스에서 원시 데이터로 사용하는 관계형 데이터베이스에 시간지원질의 처리 계층을 결합하는 방법을 보이고, 시간지원 데이터의 간격 시간에 대한 요약화 방법으로 시간지원 집계 트리 전략을 소개한다.

• Korea journal of population studies
• /
• v.22 no.2
• /
• pp.5-45
• /
• 1999

이 논문의 목적은 우리 나라에서 인구증가나 인구억제 등 인구에 관한 국민들의 가치관의 변화를 살펴보기 위한 것이다. 여기서 말하는 가치란 특정한 사회구조의 산물이며 동시에 그 사회를 구성하는 개인들의 행위의 동기가 되며 행위의 지침이 되는 모든 태도와 관심을 말한다. 우리 나라는 1960년대 초부터 정부가 주도하여 실시한 가족 계획 사업을 국민들이 적극적으로 받아 들여 출산율의 억제에 성공한 대표적인 나라로 손꼽힌다. 이에 따라 우리 나라에서는 많은 조사 특히 인구억제를 위한 피임 및 자녀수에 대한 조사연구를 했다. 이들 조사는 대부분 질문표를 이용한 조사였기에 실제 상황에 접하지 않고 가상적인 상황을 설정하여 그에 대한 반응을 알아 낸 자료이기에 실제상황에 봉착했을 때 꼭 그와 같이 행동하리라는 보장은 없다. 위와 같은 단점을 고려하여 주요 신문의 사설을 국민감정과 가치를 대변하는 가장 적합한 자료로 이용했다. 우리 나라에서 지난 수십년간 가장 큰 영향을 미친 대중매체는 신문이었으며 또한 오늘날까지 계속 발간되고 있는 신문으로서 동아일보와 조선일보를 손꼽을 수 있다. 1955년부터 1996년 말까지 두 신문이 밝나한 사설의 수는 30,000여 편을 넘는다. 인구에 간접적으로 관련되는 사설의 수는 수백 수천편에 달하겠으나 직접적으로 관련된 사설을 130편으로 집계되었다. 이 자료를 인구증가, 산아제한 및 가족계획, 법 및 정책, 인구 재분배, 수도권 인구 억제, 인구와 사회문제, 노동력과 취업, 및 인구자료-센서스 등 8가지 범주로 구분했다. 이들 각각에 대한 관점을 5년 간격으로 제시하고 마지막으로 역년(曆年) 5년 간격으로 그 주요 쟁점의 변화를 요약했다.

• Journal of Digital Convergence
• /
• v.12 no.6
• /
• pp.155-160
• /
• 2014

When we collect marketing data, we can only obtain the bimonthly or quarterly data but the monthly data be available. If we evaluate or predict monthly market condition or establish monthly marketing strategies, we need to disaggregate these bimonthly or quarterly data to the monthly data. In this paper, for bimonthly or quarterly data, we introduce some methods of disaggregation to monthly data. These disaggregation methods include the simple average method, the growth rate method, the weighting method by the judgment of experts, and variable decomposition method using 12 month moving cumulative sum. In this paper, we applied variable decomposition method to disaggregate for bimonthly data of sum of electronics sales in a European country. We, also, introduce how to use this method to predict the future data.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.9 no.6
• /
• pp.63-82
• /
• 2010

In spite of continuous road construction, traffic congestion has been worsening by radical vehicle's increase and development of surroundings near expressway. Thus, the necessity of traffic management and the needs of provision of traffic information to drivers are raised. In order to solve traffic problems, such as traffic congestion, search for optimal congestion management technique and evaluation of the effect of optimal solution should be examined prior to practice of optimal alternative. However, existing traffic analysis model and simulation programs as tools to search and evaluate optimal alternative are not sufficient to reflect traffic flow characteristics, domestic road and traffic conditions and to link up to Freeway Traffic Management Systems (FTMS). Hence, to use existing traffic analysis and simulation tools are followed by hard work to need a lot of time and cost. Therefore, in this research, Expressway TRaffic Analysis Model (ExTRAM) based on Freeway Traffic Management Systems (FTMS) was developed to apply it into congestion management easily.