• Journal of Communications and Networks
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• 제7권1호
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• pp.54-64
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• 2005

This paper presents an advanced architecture for a traffic generator capable of producing ATM traffic streams according to fully general semi-Markovian stochastic models. The architecture employs a basic traffic generator platform and enhances it by adding facilities for 'driving' the cell generation process through high-level specifications. Several kinds of optimization are employed for enhancing the software's speed to match the hardware's potential and for ensuring that traffic streams corresponding to models with a wide range of parameters can be generated efficiently and reliably. The proposed traffic generation procedure is highly modular. Thus, although this paper deals with ATM traffic, the main elements of the architecture can be used equally well for generating traffic loads on other networking technologies, IP-based networks being a notable example.

• 대한교통학회지
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• 제22권7호
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• pp.131-137
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• 2004

기존 신호최적화모형에서 횡단시간은 직진신호시간에 대한 최소녹색신호시간으로 분석가에 의해 외부에서 주어지게 된다. 이로 인하여 실제로 차량이동류들에 대한 신호시간이 교통량/포화교통량 비에 의해 적절하게 배분되지 못하고 있는 실정이다. 따라서 본 연구에서는 횡단시간을 차량이동류와 동등한 이동류로 간주하여 이들을 동시에 최적화하는 신호최적화모형을 혼합정수선형계획법(BMILP)으로 제시하였다. 이를 위하여 차량 및 보행자 이동류들이 교차로를 상충없이 통과할 수 있도록 하는 선형제약조건들과 목적함수들을 구축하였다. 제시된 모형은 적색시간에 발생되는 주 대기차량과 대기차량이 소거되는 동안에 대기차량 후미에서 발생되는 부 대기차량으로 구분하여 이들 에게 발생되는 지체시간의 상대적인 크기를 반영해주는 대기차량을 모형화하고 이를 최소화해 주는 차량 및 보행자를 위한 신호시간을 산정해주게 된다. 횡단시간과 접근로에서의 횡단보도 수 에 따라 구분된 시나리오들에 대한 모형 적용 결과 기존 TRANSYT-7F 보다 신호주기에 대한 비율이 작으면서도 큰 횡단시간을 얻을 수 있었다. 그리고 시뮬레이션 결과 TRANSYT-7F 적용시보다 지체시간이 감소되는 것으로 나타났으며 횡단시간이 클수록 그 감소효과가 큰 것으로 나타났다.

• 대한교통학회지
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• 제29권4호
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• pp.113-123
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• 2011

최근에 활발히 진행된 ITS사업과 신호개선사업으로 인해 신호제어 시스템의 온라인화와 실시간 신호제어시스템이 도입되어 교통신호제어기의 첨단화가 진행되었다. 하지만 실시간 신호제어 운영변수 산정의 기초가 되고, 현재 가장 일반적으로 이용되는 신호교차로의 제어방법으로 사용되는 TOD제어의 운영을 위한 효과적인 신호시간계획을 위한 방법론이 부재되어 왔다. TOD 시간계획의 최적화를 수행하는 과정은 신호교차로의 효율성 제고를 위해 매우 중요한 작업이며, 최적화 수행과정의 정립이 필요한 실정이다. 본 연구에서는 TOD 시간계획 작성 시 가장 선행되어야 할 Sub Area 결정 방법과 첨두시와 비첨두시의 시간 경계를 결정하는 방법론에 대해서 정의하고, 각 방법론에 의해 결정된 시간경계 구간의 신호제어 변수를 신호최적화 모형을 통해 산출하였다. 최적화된 신호제어 변수의 효과를 분석하기 위해 서울시의 동2로 간선도로 구간에 새로운 TOD 시간계획을 적용하고 필드테스트를 수행하였으며, 이러한 TOD 시간계획의 적용 효과를 사전/사후 분석을 통해 검증하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.32-35
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• 1996

Traffic signal cycle optimization is one of the most efficient ways for reducing fuel consumption and improving vehicle waiting time of highsaturated traffic conditions. But most research focused on lowsaturated traffic conditions. Only a few studies have researched traffic control for highsaturated traffic conditions. In this paper reviews the problem of conventional traffic signal system and creates optimal traffic cycle of at the bottom traffic intersection using 27 fuzzy rules. Moreover, to prevent spillback, it can adapt control even though upper traffic intersection has a different saturation rate, road length, road slope and road width.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 B
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• pp.735-738
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• 1997

The traffic congestion caused by the exploding increase of vehicles became one of the severest social problems. Among the various approaches to solve this problem, controlling the length of traffic signals appropriately according to the individual traffic situation would be the most plausible and cost-effective method. To design a traffic signal controller which has such a property as adaptive decision-making process, we adopt fuzzy logic control method(fuzzy traffic signal controller), Moreover, using genetic algorithms we obtain an optimized fuzzy traffic signal controller (GA-fuzzy traffic signal controller). To evaluate and validate the proposed fuzzy and GA-fuzzy traffic signal controller, simulation results are presented.

• 한국도로학회논문집
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• 제15권6호
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• pp.125-133
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• 2013

PURPOSES : The purpose of this study is to propose delay-minimizing operation methodology of a signalized intersection based upon optimization of lane-uses on approaching lanes for an intersection. METHODS : For the optimization model of lane-uses, a set of constraints are set up to ensure feasibility and safety of the lane-uses, traffic flow, and signal settings. Minimization of demand to saturation flow ratio of a dual-ring signal control system is introduced to the objective function for delay minimization and effective signal operation. Using the optimized lane-uses, signal timings are optimized by delay-based model of TRANSYT-7F. RESULTS : It was found that the proposed objective function is great relation with delay time for an intersection. From the experimental results, the method was approved to be effective in reducing delay time. Especially, cases for two left-turn lanes reduced greater delays than those for a left turn lane. It is noticed that the cases for different traffic volume by approach reduced greater delays than those for the same traffic volume by approach. CONCLUSIONS : It was concluded that the objective function is proper for lane-uses optimizing model and the operation method is effective in reducing delay time for signalized intersections.

• ETRI Journal
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• 제43권5호
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• pp.799-811
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• 2021

This paper considers a challenging problem: to simultaneously optimize the cost and the quality of service in opaque wavelength division multiplexing (WDM) networks. An optimization problem is proposed that takes the information including network topology, traffic between end nodes, and the target level of congestion at each link/ node in WDM networks. The outputs of this problem include routing, link channel capacities, and the optimum number of switch ports locally added/dropped at all switch nodes. The total network cost is reduced to maintain a minimum congestion level on all links, which provides an efficient trade-off solution for the network design problem. The optimal information is utilized for dynamic traffic in WDM networks, which is shown to achieve the desired performance with the guaranteed quality of service in different networks. It was found that for an average link blocking probability equal to 0.015, the proposed model achieves a net channel gain in terms of wavelength channels (𝛾_w) equal to 35.72 %, 39.09 %, and 36.93 % compared to shortest path first routing and 𝛾_w equal to 29.41 %, 37.35 %, and 27.47 % compared to alternate routing in three different networks.

• 한국경영과학회지
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• 제34권1호
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• pp.61-83
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• 2009

This study developed a variable demand traffic assignment model by stable dynamics. Stable dynamics, suggested by Nesterov and do Palma[19], is a new model which describes and provides a stable state of congestion in urban transportation networks. In comparison with the user equilibrium model, which is based on the arc travel time function in analyzing transportation networks, stable dynamics requires few parameters and is coincident with intuitions and observations on congestion. It is therefore expected to be a useful analysis tool for transportation planners. In this study, we generalize the stable dynamics into the model with variable demands. We suggest a three stage optimization model. In the first stage, we introduce critical travel times and dummy links and determine variable demands and link flows by applying an optimization problem to an extended network with the dummy links. Then we determine link travel times and path flows in the following stages. We present a numerical example of the application of the model to a given network.

• 한국정보통신학회논문지
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• 제25권4호
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• pp.572-580
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• 2021

네트워크에서 전송지연을 줄이고 신뢰성을 높이기 위해 주로 고성능 및 고출력의 네트워크 장비를 사용하여 네트워크 품질을 보장하고 있다. 본 논문에서는 다수의 물리적 케이블로 이루어진 번들 링크를 가진 네트워크에서 트래픽 전송 시 소모되는 에너지를 최소화하기 위한 최적화 알고리즘을 제안한다. 제안된 최적화 알고리즘은 메타휴리스틱방식 중 하나인 타부서치 알고리즘을 적용하였으며, 각 트래픽에 대하여 소스 노드와 목적지 노드의 경로상에 있는 케이블을 최소로 선택하여 전송에너지가 최소화되도록 설계하였다. 제안된 최적화 알고리즘은 네트워크상의 모든 트래픽에 대하여 전송상에 사용되는 케이블의 수와 링크 효율 관점에서 성능평가가 수행되었으며, 성능평가 결과에서 이전에 제안된 방식보다 우수한 성능을 확인할 수 있었다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.129-145
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• 2020

The article presents a systematic approach to design of marine navigation channels parameters resulting from manoeuvring and operational safety. Relations between the parameters of waterway system elements and the conditions of safe ship operation have been determined and the objective function of waterway parameters' optimization problems has been minimized with respect to variables of construction and operation costs. These costs have been functionally associated to variables of channel width at the bottom and fairway depth. The method of fairway's width computation at specified safe depth at the preliminary and detailed stages of waterway design has been proposed. The results of this method application have been illustrated with two examples: 1. The modernization of Szczecin-Swinoujscie fairway aimed at accepting vessels of 60,000 DWT capacity. 2. Construction of an approach channel leading to a newly built container terminal in Swinoujscie harbour (Poland), handling ocean-going container ships of 20,000 TEU capacity.