• Journal of Communications and Networks
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• 제6권2호
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• pp.173-181
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• 2004

This paper shows a technique for regulating the rate emitted by UWB mobile terminals. This technique is designed to adapt the emission rate to the effects of channel capacity variations. We assume that individual flows are shaped at edge routers by means of dual leaky buckets. The proposal is based on the evaluation of certain parameters, which reflect the channel status, sent to the application layer. This information is generated by the scheduler designed to guarantee appropriate channel sharing for the various traffic components. We describe some results which highlight how performance depends on the specific operating conditions, as well as on the traffic descriptors of the flows, their reciprocal difference, and performance requirements.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.66-66
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• 2000

In this parer, we introduce an algorithm to control flows of the traffic in multi-intersections. It is pointed out that the main problem in traffic control is how to resolve the congested situations for the particular time-durations and directions. The heavy load to a certain direction usually leads the intersection to congested situations, and the adjacent intersections are affected. We control and analyze the traffic flow of multi-intersections consisting of five intersections, in which four intersections are linked to the four directions of the central one. The entrance of vehicles of each direction is described using the concept of probability. We compare the performance of the pretimed signal controls to the traffic adaptive signal controller using a Petri Net simulation tool, Exspect.

• Journal of Information Processing Systems
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• 제7권1호
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• pp.1-16
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• 2011

With the increasing number of vehicles in use in our daily life and the rise of traffic congestion problems, many methods and models have been developed for real time optimisation of traffic lights. Nevertheless, most methods which consider real time physical queue sizes of vehicles waiting for green lights overestimate the optimal cycle length for such real traffic control. This paper deals with the development of a generic hybrid model describing both physical traffic flows and control of signalised intersections. The firing times assigned to the transitions of the control part are considered dynamic and are calculated by a simplified optimisation method. This method is based on splitting green times proportionally to the predicted queue sizes through input links for each new cycle time. The proposed model can be easily translated into a control code for implementation in a real time control system.

• 전자공학회논문지S
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• 제34S권3호
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• pp.1-11
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• 1997

Since the radio spectrum is limited, future wireless system will have micro cellular architecture in order to provide multimedia traffic services on personal communicatons network. The small coverage area of micro cellular systems results in frequent hadnoffs and location updates. We focuse on network load and terminal power due to frequent location updates and propose a location tracking scheme using embedded-pager PCS terminals. The proposed scheme is expected to minimize theconsumption of PCS terminal powr and improve the receiving rate of callee because of the power saving mechanism and the embedded-pager PCS terminal. This paper proposes signaling flows among the network elements for the proposed location tracking scheme. The signaling flows are accomodated to not only the existed network architectures but alsothe ATM backbone network arcitecture. To verify the signaling flows, we used petri-Net model. The resutls show that the signaling flows are suitable to our proposed location tracking scheme.

• Journal of Information Processing Systems
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• 제13권6호
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• pp.1544-1553
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• 2017

The network coding mechanism has attracted much attention because of its advantage of enhanced network throughput which is a desirable characteristic especially in a multi-hop wireless network with limited link capacity such as the device-to-device (D2D) communication network of 5G. COPE proposes to use the XOR-based network coding in the two-hop wireless network topology. For multi-hop wireless networks, the Distributed Coding-Aware Routing (DCAR) mechanism was proposed, in which the coding conditions for two flows intersecting at an intermediate node are defined and the routing metric to improve the coding opportunity by preferring those routes with longer queues is designed. Because the routes with longer queues may increase the delay, DCAR is inefficient in delivering real-time multimedia traffic flows. In this paper, we propose a network coding-aware routing protocol for multi-hop wireless networks that enhances DCAR by considering traffic load distribution and link quality. From this, we can achieve higher network throughput and lower end-to-end delay at the same time for the proper delivery of time-sensitive data flow. The Qualnet-based simulation results show that our proposed scheme outperforms DCAR in terms of throughput and delay.

• 한국경영과학회지
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• 제11권2호
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• pp.13-26
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• 1986

This paper considers the routing problem in session-based communication network, particularly where the pattern of message transmission is characterized by non-bifurcated traffic flows. Due to the discreteness property of its solution space, the problem is formulated as normalized mlticommodity network flows with integer restrictions and an effective penalty system is suggested to solve it. To show its effectiveness, a simple example and a preliminary computational experience are provided. Finally, numerous application areas of the algorithm are suggested.

• 한국정보통신학회논문지
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• 제10권12호
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• pp.2221-2229
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• 2006

최근 모바일 단말기의 위치정보를 활용하는 주요 응용 중의 하나인 최적 경로 탐색 시스템은 출발지와 목적지간의 거리뿐만 아니라 탐색 되어지는 구간에 존재하는 많은 교통 상황들을 파악하고 이를 경로 탐색에 활용해야 한다. 그러나 기존의 경로 탐색 알고리즘은 교통상황들을 적절히 이용하지 못하고 있다. 이 논문에서는 새로운 최적 경로 알고리즘을 제안한다. 알고리즘은 최적 경로를 검색하기 위해 교통상황을 고려하고, 연산비용을 줄이기 위해 도로를 그리드 형태로 나누어 각각의 평균속도를 가지고 휴리스틱 가중치를 부여한다. 또한 알고리즘의 전체 수행시간, 노드 접근 횟수, 최적경로의 정확도를 항목으로 하는 실험을 수행하여 기존의 탐색 알고리즘인 Dijkstra 알고리즘과 A*알고리즘과의 성능평가를 실시하였다. 실험 결과 제안한 알고리즘이 타 알고리즘에 대해 좋은 성능을 보여주었다. 제안한 알고리즘은 향상된 응용을 지원하는 텔레매틱스 시스템에 유용하게 사용될 것으로 기대된다.

• 대한교통학회지
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• 제24권4호
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• pp.149-159
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• 2006

본 연구에서는 관측 링크통행량을 이용하여 기종점(OD) 통행량을 추정하는 두 가지 방법을 제시하며, 기존 연구들과는 달리 확률적 통행배정(stochastic traffic assignment)모형을 이용한다 확률적 통행배정모형을 이용할 경우, 운전자들이 갖고 있는 경로 대안간의 인지오차(perceived error)를 모형에 반영할 수 있으며, 링크통행량과 OD 통행량사이에 명시적인 함수관계가 존재하여 쉽게 OD 통행량을 구할 수 있다는 장점이 있다. 본 연구에서는 이런 관계식을 이용하여 두 가지의 OD통행량 추정모형을 개발하며 이를 풀기 위한 알고리듬을 제시한다. 첫 번째 모형식은 관측교통량과 추정교통량간의 차이를 최소화시키는 미분값에서 도출되며 OD통행량 추정과 관련된 변수들과의 민감도(sensitivity)값도 도출한다. 두 번째 모형식은 관측교통량에 접근하는 추정교통량의 동적과정(dynamic process)을 통하여 도출된다. 본 연구에서 제시된 OD통행량 추정모형들은 가상 예제 교통망을 대상으로 평가하며 각 모형의 장단점을 기술한다. 또한, OD통행량 추정문제가 갖는 다수의 해(multiple solutions)에 대해서도 간단히 살펴본다.

• ETRI Journal
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• 제30권2호
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• pp.183-193
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• 2008

In this paper, we propose quality of service mechanisms for flow-based routers which have to handle several million flows at wire speed in high-speed networks. Traffic management mechanisms are proposed for guaranteed traffic and non-guaranteed traffic separately, and then the effective harmonization of the two mechanisms is introduced for real networks in which both traffic types are mixed together. A simple non-work-conserving fair queuing algorithm is proposed for guaranteed traffic, and an adaptive flow-based random early drop algorithm is proposed for non-guaranteed traffic. Based on that basic architecture, we propose a dynamic traffic identification method to dynamically prioritize traffic according to the traffic characteristics of applications. In a high-speed router system, the dynamic traffic identification method could be a good alternative to deep packet inspection, which requires handling of the IP packet header and payload. Through numerical analysis, simulation, and a real system experiment, we demonstrate the performance of the proposed mechanisms.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권9호
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• pp.2191-2201
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• 2012

Traffic classification seeks to assign packet flows to an appropriate quality of service (QoS) class based on flow statistics without the need to examine packet payloads. Classification proceeds in two steps. Classification rules are first built by analyzing traffic traces, and then the classification rules are evaluated using test data. In this paper, we use self-organizing map and K-means clustering as unsupervised machine learning methods to identify the inherent classes in traffic traces. Three clusters were discovered, corresponding to transactional, bulk data transfer, and interactive applications. The K-nearest neighbor classifier was found to be highly accurate for the traffic data and significantly better compared to a minimum mean distance classifier.