• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.6
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• pp.26-36
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• 2021

In this study, a deep learning model for predicting the queue length was developed using the information collected from the image detector. Then, a multiple regression analysis model, a statistical technique, was derived and compared using two indices of mean absolute error(MAE) and root mean square error(RMSE). From the results of multiple regression analysis, time, day of the week, occupancy, and bus traffic were found to be statistically significant variables. Occupancy showed the most strong impact on the queue length among the variables. For the optimal deep learning model, 4 hidden layers and 6 lookback were determined, and MAE and RMSE were 6.34 and 8.99. As a result of evaluating the two models, the MAE of the multiple regression model and the deep learning model were 13.65 and 6.44, respectively, and the RMSE were 19.10 and 9.11, respectively. The deep learning model reduced the MAE by 52.8% and the RMSE by 52.3% compared to the multiple regression model.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.2 no.1 s.2
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• pp.63-73
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• 2003

COSMOS(Cycle, Offset, Split Model for Seoul), a real-time traffic adaptive signal system. estimates queue lengths on each approach on the basis of arithmetic average spot speeds calculated on loop detectors installed at each of two adjacent lanes. In this paper, A new method, a traffic volume-weighted average method, was studied and compared with the existing arithmetic average method. It was found that the relationship between the ratio of volumes of two lanes and the difference of average speed of each lane has a linear form. With field data, The two methods were applied and the proposed method shows more stable and reasonable queue estimation results.

• The Transactions of the Korea Information Processing Society
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• v.5 no.1
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• pp.33-39
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• 1998

A queueing model for performance evaluation of finite buffered inter-node communication system is proposed in this paper. Each components are modeled as M/M/I/B queues to obtain the steady state probabilities and ar-rival rate and to analyze finite buffer behavior, The overall sysrem is integrated as series queues with blocking. Average delay and throughput are the performance measures studied in this analysis. The analytical results are first validated through simulation. Next, the effect of buffer length is discussed using the proposed model.

• Journal of the Korea Society for Simulation
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• v.16 no.2
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• pp.75-81
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• 2007

Previous queue inference has been studied with some limits. Larson's inference engine, which is the basis for this paper, also processed with basic assumption that arrival process is poisson process. Our inference method, which relaxes the poisson process assumption, must be a useful tool for looking into unobservable inside of queueing systems, as well as calculating accurate system performance. This paper employs these inference methods and proves the validity. Then we apply this method to system analysis for more complicated models. At first, we suggest methods to system with known number of servers, then expand to unknown number of servers. For validating our inference approach, we run some simulation models and compare true values with our results.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.866-872
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• 2005

본 연구는 비축출형 우선순위 2-계층 대기행렬을 다룬다. 각 계층별 고객들은 마코비안 도착과정(Markovian arrival process, MAP)에 의하여 시스템에 도착하고, 각 계층마다 고유의 임계점을 갖는다. 시스템 내에 고객들이 존재하지 않으면 서어버는 유휴해지고 어느 계층이든지 상관없이 계층에 부여된 임계점에 먼저 도달하면 서어버는 서비스를 시작한다. 우선순위가 높은 고객들을 먼저 서비스하는 비축출형 우선순위 서비스규칙을 따른다. 본 연구에서는 각 계층별 고객들의 대기시간분포에 대한 라플라스(Laplace-Stieltjes) 변환과 평균 대기시간을 유도한다.

• Journal of the Korea Society for Simulation
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• v.23 no.3
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• pp.1-9
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• 2014

Traditional workflow time analyses have been performed treating an activity as an independent M/M/1queueing system. Using the general forms of performance measures in the M/M/1 system, various aspects of analyses can be performed. Especially, on the time analysis of an AND structure in a workflow system, the mean system sojourn time can be formalized by applying the performance measures of M/M/1 system. In the real workflow system, the AND structure cannot be described correctly under the assumption of independent M/M/1 systems. To overcome this limitation, this research makes the assumption that the all activities for a task starts simultaneously. In this situation, the theoretical solution can be derived using the performance measures of the M/G/1 system. In addition, the simulation modeling method will be proposed to analyze the AND structure of a real workflow system. Finally, some numerical results from the theoretical solutions and simulation models will be provided for verification. The main performance measures used in this research are mean queueing time and mean sojourn time.

• Journal of Korean Institute of Industrial Engineers
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• v.22 no.3
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• pp.377-385
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• 1996

We present an approximate algorithmic approach for the m-server fork-join queueing system with infinite queue capacity. We analyze the system size and queue waiting time. We assume Poisson arrival process and independent exponential service times.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.265-267
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• 2000

가공물을 한 개씩 작업하는 단일작업기계와 여러 개의 가공물을 한꺼번에 작업하는 배치 기계를 포함한 재진입 라인 시스템에서 각 기계가 고장이 일어날 수 있고, 불량품이 발생할 때, 이 시스템에서의 가공물의 생산주기를 구하는 방법을 Mean Value Analysis(MVA)를 이용하여 제시하고자 한다. 배치 기계와 고장 발생, 불량품 발생 등의 이유의 이런 시스템은 승법형 대기행렬 모형으로 모형화 할 수 없다. 본 논문에서는 각 기계에서의 체류 시간을 구하여 전 시스템의 생산 주기를 구하는 방법을 MVA 를 이용하여 제시한다.

• Journal of the Korean Operations Research and Management Science Society
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• v.7 no.1
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• pp.5-9
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• 1982

우리나라 경영학계 내지는 기업경영에 경영과학(Management Science)의 여러가지 기법이 정식으로 소개되기 시작한 것은 70년대 후반이라고 생각된다. 경영과학의 기법에는 선형계획법·재고관리모형·대기행렬모형·모의(Simulation) 모형·네트웍(Network) 모형 등 여러가지가 있지만, 이중 선형계획법이 우리에게 가장 익숙한 모형이고 기업의 실제 문제해결에도 가장 많이 이용되고 있다. 지금 소개하고자 하는 목표계획법도 경영과학기법의 하나로 모형계획법과 매우 유사한 기법이다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.2
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• pp.22-34
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• 2011

This paper presents the investigation results of a research on how engineers can analyze the economic effect of the ETCS(Electronic Toll Collection System) installed to minimize the vehicle delays on freeway tollgates during toll payments. This research considered this economic effect to occur in the form of vehicle passing time reductions at the ETCS, and the multi-service queuing theory was applied to estimate these values. This research found: 1) When vehicles approaching tollgates show Poisson distribution and the service time of the ETCS shows Exponential distribution, the multi-service queuing theory would be applicable for estimating vehicle passing times at toll-gates, 2) Despite the ETCS placement, exit sections of tollgates give a greater reduction of vehicle passing times than entering sections due to more delays at conventional toll payments, and 3)The ETCS would not guarantee vehicle passing time reductions all the time, because in such a case as many vehicles were queuing at the ETCS, the total delay level for a toll gate would increase greatly. In addition, in order to examine the accuracy of the estimated vehicle passing values, this research compared the values from the multi-service queuing theory with the observed values from a set of field survey values at freeway toll-gates, and found that the two values were in a good agreement with a very low error range of 1-3 seconds per vehicle. Based on this result, the multi-service queuing theory was recommended for practice.