• Journal of Korean Society of Transportation
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• v.22 no.5
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• pp.123-137
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• 2004

The study on traffic assignment is actively being performed which reflect networks status using time. Its background is increasing social needs to use traffic assignment models in not only hardware area of road network plan but also software area of traffic management or control. In addition, multi-class traffic assignment model is receiving study in order to fill a gap between theory and practice of traffic assignment model. This model is made up of two, one of which is multi-driver class and the other multi-vehicle class. The latter is the more realistic because it can be combined with dynamic model. On this background, this study is to build multidynamic model combining the above-mentioned two areas. This has been a theoretic pillar of ITS in which dynamic user equilibrium assignment model is now made an issue, therefore more realistic dynamic model is expected to be built by combining it with multi-class model. In case of multi-vehicle, FIFO would be violated which is necessary to build the dynamic assignment model. This means that it is impossible to build multi-vehicle dynamic model with the existing dynamic assignment modelling method built under the conditions of FIFO. This study builds dynamic network model which could relieve the FIFO conditions. At the same time, simulation method, one of the existing network loading method, is modified to be applied to this study. Also, as a solution(algorithm) area, time dependent shortest path algorithm which has been modified from existing shortest path algorithm and the existing MSA modified algorithm are built. The convergence of the algorithm is examined which is built by calculating dynamic user equilibrium solution adopting the model and algorithm and grid network.

• The Korean Journal of Applied Statistics
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• v.36 no.4
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• pp.349-360
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• 2023

Dynamic Nelson-Siegel model is widely used in modeling term structure of interest rates for financial products. In this study, we explain dynamic Nelson-Siegel model from the perspective of the state space model and explore Bayesian approaches that can be applied to that model. By applying SOFR term rate data to the Bayesian dynamic Nelson-Siegel model, we confirm the performance and compare it with other competing models such as Vasicek model, dynamic Nelson-Siegel model based on the frequentist approach, and the two-factor Bayesian dynamic Nelson-Siegel model. We also confirm that the Bayesian dynamic Nelson-Siegel model outperformed its competitors on SOFR term rate data based on RMSE.

• Journal of Korean Society of Transportation
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• v.26 no.6
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• pp.123-132
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• 2008

Dynamic origin-destination (OD) trip matrix has been widely used for transportation fields such as dynamic traffic assignment, traffic operation and travel demand management, which needs precise OD trip matrix to be collected. This paper presents a quasi-dynamic OD matrix estimation model and applies it to real road network for collecting the dynamic OD matrix. The estimation model combined with dynamic traffic assignment program, DYNASMART-P, is based on GPS embedded in PDA, which developed for collecting sample dynamic OD matrix. The sample OD matrix should be expanded by the value of optimal sampling ratio calculated from minimization program. From application to real network of Jeju, we confirm that the model and its algorithm produce a reasonable solution.

• Journal of Korean Society of Transportation
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• v.15 no.2
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• pp.51-66
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• 1997

실시간 변화하는 교통상황을 파악하고 교통혼잡을 완화시키려는 각종 교통정책들을 개발하고 평가하기 위하여 동적 통행배정모형에 대한 연구가 지속되고 있으며 상당한 성과 를 이루고 있다. 그러나 이론적인 어려움과 계산량과 과다로 기존의 모형들은 대부분 단순 가로망을 대상으로 적용되어 왔으며 대규모 가로망에 적용하는 데는 상당한 어려움을 겪고 있다. 본 연구의 목적은 실제 가로망에 쉽게 적용할 수 있는 휴리스틱 동적 통행배정모형을 개발하고 이를 해석할 수 있는 알고리즘을 개발하는 데 있다. 개발되는 모형은 변동부등식 (variational inequality)으로 구축되며 알고리즘은 휴리스틱 알고리즘(heuristic disagonalized algorithm)을 개발한다. 예제 가로망을 대상으로 개발된 모형을 평가하며 도출된 해가 Wrdrop의 균형해(equilibrium)임을 보인다.

• Journal of Korean Society of Transportation
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• v.17 no.4
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• pp.71-84
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• 1999

The purpose of this study is to construct a dynamic traffic analysis model using the existing traffic flow theory in order to develope a dynamic traffic assignment technique. In this study the dynamic traffic analysis model was constructed using Daganzo's CELL TRANSMISSION THEORY which was considered more suitable to dynamic traffic assignment than the other traffic flow theories. We developed newly the diverging split module, the cost update module and the link cost function and defined the maximum waiting time decision function that Daganzo haven't defined certainly at his Papers. The output that resulted from the simulation of the dynamic traffic analysis model with test network I and II was shown at some tables and figures, and the analysis of the bottleneck and the HOV lane theory showed realistic outputs. Especially, the result of traffic assignment using the model doesn't show equilibrium status every time slice but showed that the average travel cost of every path maintains similarly in every time slice. It is considered that this model can be used at the highway operation and the analysis of traffic characteristics at a diverging section and the analysis of the HOV lane effect.

• Journal of Korean Society of Transportation
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• v.19 no.3
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• pp.101-113
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• 2001

Since late 1970s. one of the principal research areas in transportation problem is dynamic traffic assignment (DTA). Although many models have been developed regarding DTA, yet they have some limits of describing real traffic patterns. This reason comes from the fact that DTA model has the time varying constraints such as state equation, flow propagation constraint, first in first out(FIFO) rule and queuing evolution. Thus, DTA model should be designed to satisfy these constraints as well as dynamic route choice condition, dynamic user equilibrium. In this respect, link-based DTA models have difficulty in satisfying such constraints because they have to satisfy the constraints for each link, while path-based DTA models may easily satisfy them. In this paper we develop a path-based DTA model. The model includes point queue theory to describe the queue evolution and simulation loading method for depicting traffic patterns in more detail. From a numerical test, the model shows promising results.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.4 no.2
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• pp.55-70
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• 1994

본 논문은 데이타베이스의 동적 기능을 모형화하기 위해서 동적 규칙을 사건과 동적 규칙 객체로 취급하여 개념적 스키마에 표현하는 동적 객체지향 데이타 모델을 제안한다. 제안된 모델에서 정적 구조와 동적 구조에 대한 개념들을 정의하고 모형화 과정에서 사용자의 이해도를 증진시키는 모델의 구성요호에 대한 그래픽 다이어그램을 제시하였다. 그리고 동적 규칙이 데이타베이스 구조에 포함됨으로써 발생가능한 정보의 불법적인 노출 또는 변경을 방지하기 위해서 BLP모델의 보안 정책을 확장하여 제안된 모델에 대한 11가지 종류의 다단계 보안 성질들을 정의하였다. 또한, 정의된 다단계 보안 성질들이 타당한가를 조사하기 위해서 패트리네트를 확장하여, 보안 성질의 검증작업을 수행하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.378-378
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• 2017

본 연구는 도시에서 발생하는 홍수에 대응하기 위해서 홍수취약요인을 구성하고 홍수 위험성을 기반으로 취약지역과 정도를 도출하는 동적의사결정 모형 구성을 목표로 한다. 취약 요인은 인명피해에 초점을 맞추었으며 발생 가능한 홍수의 규모에 따른 취약 요인의 대응역량 등을 반영하여 동적의사결정 모형을 구성하고자 한다. 홍수위험성 산정에는 예상되는 홍수 시나리오를 반영한 SWMM 모델링 결과를 이용하였으며, 취약요인은 델파이기법으로 구성하였다. 구성한 모형은 빈번하게 내수침수가 발생한 지역인 도림천 유역을 대상으로 적용성을 검토하였다. 수립된 모형은 홍수 위험성의 정도에 대하여 발생 가능한 인명피해 지역을 공간적으로 파악할 수 있도록 하며 인명피해 예상 수치를 제공할 수 있다.

• Journal of Korean Society of Transportation
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• v.25 no.4
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• pp.99-108
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• 2007

This paper presents an elastic demand stochastic user equilibrium traffic assignment that could not be easily tackled. The elastic demand coupled with a travel performance function is known to converge to a supply-demand equilibrium, where a stochastic user equilibrium (SUE) is obtained. SUE is the state in which all equivalent path costs are equal, and thus no user can reduce his perceived travel cost. The elastic demand SUE traffic assignment can be formulated based on a dynamic system, which is a means of describing how one state develops into another state over the course of time. Traditionally it has been used for control engineering, but it is also useful for transportation problems in that it can describe time-variant traffic movements. Through the Lyapunov Function Theorem, the author proves that the model has a stable solution and confirms it with a numerical example.

• The Korean Journal of Applied Statistics
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• v.15 no.2
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• pp.213-222
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• 2002

The 3-hour-interval prediction of ground-level temperature up to +45 hours in Seoul area is performed using dynamic linear models(DLM). Numerical outputs and observations we used as input values of DLM. According to compare DLM forecasts to RDAPS forecasts using RMSE, DLM improve the accuracy of prediction and systematic error of numerical model outputs are eliminated by DLM.