• 한국국방경영분석학회지
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• 제17권2호
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• pp.72-89
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• 1991

In transportation network problems, it is often desirable to select multiple number of the shortect paths. On problems of finding these paths, algorithms have been developed to choose single shortest path, k-shortest paths and k-shortest paths via p-specified nodes in a network. These problems consider the time as the main factor. In wartime, we must consider availability as well as time to determine the shortest transportation path, since we must take into account enemy's threat. Therefore, this paper addresses the problem of finding the shortest transportation path considering both time and availability. To accomplish the objective of this study, values of k-shortest paths are computed using the algorithm for finding the k-shortest paths. Then availabilties of those paths are computed through simulation considering factors such as rates of suffering attack, damage and repair rates of the paths. An optimal path is selected using any one of the four decision rules that combine the value and availability of a path.

• 한국국방경영분석학회지
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• 제16권2호
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• pp.105-117
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• 1990

In the transportation network problems, it is often more desirable to select multiple number of optimal parths to prepare for additional constratints being imposed than to choose single optimal path. This paper addresses 'the problem of finding the k-shortest paths visiting p-specified nodes in a network'. The solution method is derived and the example of application is shown. The keypoint for determining the k-shortest paths via p-specified nodes is to combine the Shier's k-shortest path algorithm and the principle of optimality of dynamic programming method. Finally, for a transportation network problem consisting of national main routes, the k-shortest paths via some specified cites are obtained by using the solution method developed here.

• 제어로봇시스템학회논문지
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• 제8권9호
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• pp.795-802
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• 2002

We present a new dynamic routing scheme for multiple autonomous guided vehicles (AGVs) systems. There have been so many results concerned with scheduling and routing of multiple AGV systems; however, most of them are only applicable to systems with a small number of AGVs under a low degree of concurrency. With an increased number of AGVs in recent applications, these AGV systems are faced with another problem that has never been occurred in a system with a small number AGVs. This is the stop propagation problem. That is, if a leading AGV stops then all the following AGVs must stop to avoid any collision. In order to resolve this problem, we propose a nonstop preferential detour (NPD) algorithm which is a new dynamic routing scheme employing an election algorithm. For real time computation, we introduce two stage control scheme and propose a new path searching scheme, k-via shortest path scheme for an efficient dynamic routing algorithm. Finally, the proposed new dynamic routing scheme is illustrated by an example.

• 대한산업공학회지
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• 제32권3호
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• pp.226-235
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• 2006

Telematics is expected to be one of the fastest growing businesses in information technology area. It may create a new emerging market in industry related to automotive, telecommunications, and information services. Especially vehicle navigation service is considered as a killer application among telematics service applications. The current vehicle navigation service typically recommends a single path that is based on the traveling time or distance from the origin to the destination. The system provides two options for users to choose either via highway or via any road. Since the traffics and road conditions of big cities are very complicated and dynamic, the demand of multi-path guidance system is increasing in telematics market. The multi-path guidance system should allow drivers to choose a path based on their individual preferences such as traveling time, distance, or route familiarity. Using the Lawler's algorithm, it is possible to find multiple paths; however, due to the lengthy computational time, it is not suitable for the real-time services. This study suggests a computationally feasible and efficient heuristic multiple paths finding algorithm that is reliable for the real-time vehicle navigation services.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2004년도 추계학술대회 및 정기총회
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• pp.225-228
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• 2004

The generalized knapsack problem, or gknap is the combinatorial optimization problem of optimizing a nonnegative linear functional over the integral hull of the intersection of a polynomially separable 0 - 1 polytope and a knapsack constraint. Among many potential applications, the knapsack, the restricted shortest path, and the restricted spanning tree problem are such examples. We prove via the ellipsoid method the equivalence between the fully polynomial approximability and a certain pseudo-polynomial separability of the gknap polytope.

• ETRI Journal
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• 제28권6호
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• pp.815-818
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• 2006

In the global Internet, a constraint-based routing algorithm performs the function of selecting a routing path while satisfying some given constraints rather than selecting the shortest path based on physical topology. It is necessary for constraint-based routing to disseminate and update link state information. The triggering policy of link state updates significantly affects the volume of update traffic and the quality of services (QoS). In this letter, we propose an adaptive triggering policy based on link-usage statistics in order to reduce the volume of link state update traffic without deterioration of QoS. Also, we evaluate the performance of the proposed policy via simulations.

• 대한기계학회논문집A
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• 제37권5호
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• pp.609-617
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• 2013

본 논문은 무인 자율 주행을 위한 최소 시간 경로계획 알고리즘에 대해서 제안하였다. 최소 시간 경로계획 문제는 경로의 기하학적인 형상에 대한 고려뿐만이 아니라 차량 동역학까지 고려해야 하는 최적 문제이다. 경로계획은 후보 경로 생성 알고리즘과 속도 최적화 알고리즘으로 구성된다. 후보 경로 생성 알고리즘은 최단 거리 경로와 최고 속도 경로를 조합하여 후보경로를 생성한다. 속도 최적화 알고리즘은 차량의 주행성능 한계와 타이어 마찰 한계를 고려하여 각 후보 경로의 최고 속도를 계산한다. 이렇게 계산된 경로와 속도를 이용하여 각 후보 경로의 주행 시간을 계산하고 가장 작은 주행 시간의 경로를 최단시간 경로로 도출한다. 그리고 제안한 알고리즘은 CarSim 과 Matlab/Simulink 를 사용한 시뮬레이션을 통해 검증하였다.

• Journal of information and communication convergence engineering
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• 제8권6호
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• pp.623-629
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• 2010

A geographical routing protocol is typically utilized for a route selection of VANET. Even if it is conceptually well adapted into VANET, message delivery tends to be unreliable with frequent network partitions, which mainly come from the inherent characteristics such as high mobility and irregular traffic density. In this paper, we deal with a method to enable reliable message delivery with reflecting the traffic density on routing decision. By concatenating the message delivery cost of each of inbetween junction section, $1^{st}$ and $2^{nd}$ shortest paths are initially determined. When it is not possible to deliver the message on a junction on the 1st path, we utilize two novel ideas, that is, letting the message stay on the junction to find out a new relay node, and putting a replicated copy to reach via a detour path. By using the NS-2 network simulator, our method has been examined in terms of message delivery rate and delay. It shows that our method is much efficient than the other method in the low density environment, while it brings similar results in the high density environment.

• 한국통신학회논문지
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• 제40권11호
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• pp.2205-2217
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• 2015

생체모방 라우팅 프로토콜은 동적 환경에서 집단 생명체가 분산 자율적인 방식으로 최적 경로를 찾아가는 원리를 이용하여 네트워크 토폴로지 변화에 따라 오버헤드를 줄이며, 라우팅 성능을 극대화하고, 경로 단절시 빠른 복구가 가능하다. 본 논문에서는 이동 애드혹 네트워크를 위한 생체모방 라우팅 프로토콜을 제안한다. 제안 방식은 추가적인 오버헤드 없이 라우팅 정보를 얻기 위하여 무선 매체의 엿듣기(overhearing) 기능을 사용한다. 엿듣기를 통해 출발지와 목적지 사이의 최단 경로 주변에 페로몬을 확산시키고, 확산된 페로몬을 기반으로 확률적 경로 탐색을 수행하여 출발지와 목적지 간 유용한 대체 경로를 확보한다. 이와 같은 방식으로 제안 프로토콜은 제어 오버헤드를 줄이면서 최신의 라우팅 정보를 획득할 수 있다. 시뮬레이션 결과 제안하는 생체모방 라우팅 프로토콜은 기존 AODV 및 AntHocNet 프로토콜 보다 우수한 라우팅 성능을 보여주면서 AntHocNet 보다 오버헤드를 크게 감소시킨다.

• 한국게임학회 논문지
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• 제4권2호
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• pp.13-20
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• 2004

우리는 도망자-추적자 게임 풀이에 관심이 많다. 도망자가 추적자를 피해 미로를 탈출하는 게임이다. 도망자가 추적자를 유인하기도 하고 벽을 이용해 교묘히 피하기도 한다. 경험에 의하면 수작업으로 풀기에는 매우 어려운 단계들도 있었다. 게임을 풀기 위한 방법으로 모델 체킹 기법을 사용하였다. 모델 체킹은 게임의 모든 상태 공간을 넓이 우선 방식으로 철저하게 탐색하기 때문에 게임을 풀 수 있는 가장 짧은 경로인 최적의 답을 구할 수 있다. 다행히 풀이 과정에서 상태 폭발 문제는 일어나지 않았고, 게임 풀이 결과를 임베디드 시스템인 레고 마인드스톰에 응용하였다. 도망자, 추적자에 해당하는 두 대의 에이전트를 만들어 게임을 구현하고 실험하여 풀이가 정확한 지를 실제 확인할 수 있었다.