• 한국컴퓨터정보학회논문지
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• 제21권1호
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• pp.59-64
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• 2016

This paper suggests heuristic algorithm with O(mn) polynomial time complexity using Excel for partially survivable networks optimization problem of cellular telecommunication systems with m cells and n hubs. This problem only can be get the solution using linear programming or LINGO software package. The proposed algorithm connects the cell to hubs in ring network with minimum cost as the connection diversity of each cell. If the traffic of ring network (T) is T>2K for ring capacity (K), we adjust the maximum cost hub to MTSO that has a ascending order of (D/DC)/${\Delta}^+$ cell with each cell traffic demand (D) and ${\Delta}^+$=(MTSO cost-maximum cost hub) than we get the $T{\leq}2K$. Finally, we adjust MTSO to the removed maximum cost hub for the cell with 2K-$T{\geq}$(D/DC) and $_{max}{\Delta}^-$. While we using like this simple method, the proposed algorithm can be get the same optimal solution for experimental data as linear programing and LINGO software package.

• 산업공학
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• 제20권2호
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• pp.216-226
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• 2007

In code-division multiple-access (CDMA) systems with soft handoff, mobile station (MS) within soft handoff region can use multiple radio channels and receive their signals from multiple base stations (BSs) simultaneously. In this paper, the effects of soft handoff region ratio (SHRR) on reverse link of a CDMA cellular system are analytically investigated. In order to analyze the network performance and quality of service (QoS) perceived by users more realistically, both the soft capacity increasing factor and the traffic load variation affected by SHRR are jointly considered and a two-dimensional continuous time Markov chain (CTMC) model is built. In the numerical example, it is observed that the optimal guard channel exists according the variations of the traffic load and propagation conditions when the proper value of SHRR is determined.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권4호
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• pp.1216-1231
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• 2021

With the increase in the population of our cities and the rapid increase in the number of private cars, urban traffic has become more and more congested. At this stage, urban public transportation has become one of the main ways to improve urban traffic congestion. Aiming at the problem of how to improve the basic capacity of buses in multi-line transfer stations, this paper conducts simulation research based on anylogic software. Through micro-simulation analysis of vehicles entering, stopping, and exiting the station, combined with the delay model theory, the vehicle is given Stop organization optimization and station layout improvement methods, so that vehicles can run in the station more stably, smoothly and safely. Case analysis shows that applying this method to the roadside parking problem, the main and auxiliary bus stations have a significant improvement in operating capacity compared with the conventional tandem double bus stations, and the service level of the main and auxiliary bus stations has been significantly improved.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권3호
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• pp.874-890
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• 2021

With the widespread deployment of the fifth-generation (5G) communication networks, various real-time applications are rapidly increasing and generating massive traffic on backhaul network environments. In this scenario, network congestion will occur when the communication and computation resources exceed the maximum available capacity, which severely degrades the network performance. To alleviate this problem, this paper proposed an intelligent resource allocation (IRA) to integrate with the extant resource adjustment (ERA) approach mainly based on the convergence of support vector machine (SVM) algorithm, software-defined networking (SDN), and mobile edge computing (MEC) paradigms. The proposed scheme acquires predictable schedules to adapt the downlink (DL) transmission towards off-peak hour intervals as a predominant priority. Accordingly, the peak hour bandwidth resources for serving real-time uplink (UL) transmission enlarge its capacity for a variety of mission-critical applications. Furthermore, to advance and boost gateway computation resources, MEC servers are implemented and integrated with the proposed scheme in this study. In the conclusive simulation results, the performance evaluation analyzes and compares the proposed scheme with the conventional approach over a variety of QoS metrics including network delay, jitter, packet drop ratio, packet delivery ratio, and throughput.

• 한국항행학회논문지
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• 제28권4호
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• pp.450-458
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• 2024

도심항공교통 (UAM; urban air mobility)의 상용화 가능성이 증가하고 있지만, 대규모 UAM 운항의 안전성을 확보하기 위한 기술적 기반은 아직 부족하다. 본 논문은 UAM 교통관리체계 내 전략적 충돌 관리 적용 방안을 도출하기 위해, 기존 항공 교통에서 활용되는 전략적 충돌 관리 기법과 UAM 관련 연구 및 기술 동향을 분석하였다. 이를 통해, 수요 및 수용량 관리 기법이 UAM 충돌 관리에 적용될 가능성이 크며, 시스템 전체론적인 접근의 필요함을 확인하였다. 특히, 비행시간의 불확실성과 대규모 운영 상황에서의 효과적인 구현을 위해 필요한 사항으로 데이터 공유, 확률론적 접근 방법 등이 식별되었다.

• 한국ITS학회 논문지
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• 제19권4호
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• pp.30-44
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• 2020

기존 논문들처럼 지체시간 감소만으로 PPLT 특성을 반영하여 PPLT의 적용 여부를 판단하는 것은 한계가 있다. 이에 본 논문에서는 지체시간 외에 통과 좌회전 교통량, 상충위험수를 사용하여 PPLT 적용방안을 제시하였다. 분석결과 좌회전 교통량이 용량 이상이면서 많을수록, 대향 직진 교통량은 용량 미만이면서 적을수록 PPLT 효과가 증가하였다. 그러나 좌회전 교통량이 용량 미만에서는 선행 신호대기 차량들이 비보호로 교차로를 통과하게 되어 지체시간은 일부 감소하지만 전체 통과 좌회전 교통량은 증가하지 않고 상충위험률은 증가하게 된다. 그리고 대향 직진 차로수가 1, 2차로에서는 상충위험수가 유사하지만 3차로 이상이 되면 크게 증가한다. 또한 PLT와 PPLT의 통과 좌회전 교통량 차이는 지체시간 차이와 유사한 패턴을 보이면서 지체시간보다 PPLT 적용 범위가 더 넓고 상충위험수와 연관성이 높게 분석되었다. 따라서 PPLT의 교통류 특성과 상충위험수 등을 고려하기 위해서는 통과 좌회전 교통량이 지체시간보다 유리하다. 즉, PLT와 PPLT의 통과 좌회전 교통량, 지체시간 차이와 대향직진 3차로 이상에서의 상충위험수를 동시에 고려하여 PPLT 적용 여부를 판단하면 지체시간만을 적용해온 기존 방안에 비해 합리적인 방안이 될 수 있을 것으로 판단된다.

• 대한교통학회지
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• 제12권1호
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• pp.117-132
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• 1994

Drivers select approach lane according to various traffic situations as well as their destination. This behavior affects the utilization of lanes and capacity analysis at urban signalized intersections. This paper presents the concept, behavior of lane utilization, and the lane utilization factors which included in the study. Preparation of Korean Highway Capacity Manual (1992). Lane utilization is affected by various traffic and geometric factors which are roadway side friction, median friction, and number of lanes, etc. and it converges to an equal utilization as the degree of saturation (V/C ratio) increase. Lane utilization factor is suggested by the degree of saturation and the number of lanes, and it is presented in this paper.

• 한국컴퓨터정보학회논문지
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• 제7권4호
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• pp.150-156
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• 2002

ITU-R에서 제시된 가입자의 기준수율(Reference Throughput)을 이용하여 IMT-2000 ATM-MSC 교환기의 트래픽 처리용량을 분석한다 IMT-2000 가입자가 요구하는 서비스를 크게 회선(음성, 회선교환 데이터. 대화식 고속 멀티미디어)와 패킷교환(단문 메시지 표준 멀티미디어, 고속 멀티미디어) 서비스로 분류하고 옥내, 보행자 및 차량용의 가입자 이용 환경을 고려한다. 음성서비스에 대해 AAL type 2를 고려하고 옥내：보행자：차량용=40：40：20%의 비율을 가정하며 256 규모의 ATM-MSC 교환기를 고려한다.

• 정보기술과데이타베이스저널
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• 제8권2호
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• pp.41-60
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• 2001

Despite the growth in Internet users, demand for multi-medial, large data files and resulting explosive growth in data traffic, there has been lack of investment in Middle-Mile, interconnection of various networks, resulting in bottleneck effect, which is acerbating. One strategy to overcome such network bottleneck is Content Delivery Network (CDN). CDN does not achieve efficient delivery of large file data through physical improvement/increase in network capacity, but by delivering large file contents, the cause of bottlenecks, from distributed servers. Since it is impracticable to physically improve networks capacity to accommodate the growth in internet traffic, CON, by strong CPs contents at cache servers deployed at major ISPs networks, is able to deliver requested contents to the requesting Web clients without the loss of data and long latency.

• ETRI Journal
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• 제21권4호
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• pp.9-22
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• 1999

This paper considers a problem of configuring both physical backbone and logical virtual path (VP) networks in a reconfigurable asynchronous transfer mode (ATM) network where links are subject to failures. The objective is to determine jointly the VP assignment, the capacity assignment of physical links and the bandwidth allocation of VPs, and the routing assignment of traffic demand at least cost. The network cost includes backbone link capacity expansion cost and penalty cost for not satisfying the maximum throughput of the traffic due to link failures or insufficient link capacities. The problem is formulated as a zero-one non-linear mixed integer programming problem, for which an effective solution procedure is developed by using a Lagrangean relaxation technique for finding a lower bound and a heuristic method exploited for improving the upper bound of any intermediate solution. The solution procedure is tested for its effectiveness with various numerical examples.