• Management Science and Financial Engineering
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• 제4권2호
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• pp.1-13
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• 1998

The Shortest Path Problem in Time-dependent Networks, where the travel time of each link depends on the time interval, is not realistic since the model and its solution violate the Non-passing Property (NPP:often referred to as FIFO) of real phenomena. Furthermore, solving the problem needs much more computational and memory complexity than the general shortest path problem. A new model for Time-dependent Networks where the flow speeds of each link depend on time interval, is suggested. The model is more realistic since its solution maintains the NPP. Solving the problem needs just a little more computational complexity, and the same memory complexity, as the general shortest path problem. A solution algorithm modified from Dijkstra's label setting algorithm is presented. We extend this model to the problem of Minimum Expected Time Path in Time-dependent Stochastic Networks where flow speeds of each link change statistically on each time interval. A solution method using the Kth-shortest Path algorithm is presented.

• 한국농공학회지
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• 제40권1호
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• pp.106-117
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• 1998

The nature of stress-path dependency, the principle that governs deformations in granular soil, and the use of Lade's double work-hardening model for predicting soil response for a variety of stress-paths have been investigated, and are examined The test results and the analyses presented show that under some conditions granular soils exhibit stress-path dependent behavior. For stress-paths involving unloading or reloading, the stress-path with the higher average stress level produces the larger strains, whereas all stress-paths having the same intial states of stress, and involving only primary loading conditions, produce strains of similar magnitudes. Experimental evidence indicates that the stress- path dependent response obtained from the double work-hardening model is also observed for real soils. It is concluded that the influence of stress history on the friction angle is negligible and the strains increment direction is uniquely determined from the state of stress but is not perpendicular to the yield surface. The strains calculated from Lade's double work-hardening model are in reasonable agreement with those measured.

• Journal of Mechanical Science and Technology
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• 제15권2호
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• pp.210-216
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• 2001

This paper presents an analytical study that can predict the path-dependent forming limit of anisotropic sheet materials that experience various combinations of strain paths. To predict the forming limit diagrams(FLD), the proposed analytical procedure is performed within the framework of the Marciniak and Kuczynski(M-K) approach by using the Barlat and Lians non-quadratic anisotropic yield criterion and introducing the effect of the existence of a strain gradient over a stretching punch. The predicted path-dependent forming limit of an anisotropic sheet has been compared with the published experimental results. It has been found that the predicted path-dependent forming limits are in good agreement with the experimental data.

• 대한교통학회지
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• 제24권5호
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• pp.77-88
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• 2006

본 연구는 복합교통망의 실시간적 운영전략에 활용 가능한 동적 K최소시간경로탐색알고리즘을 제안하는 것을 목적으로 한다. 이를 위해 정적 K경로탐색에 적용되었던 전체경로삭제방안을 동적 최적경로탐색알고리즘에 확장 적용함으로써 복합교통망에서 시간종속적으로 변화하는 수단-링크 통행시간과 수단-링크간의 환승비용에 기초하여 경로를 순차적으로 탐색하는 K경로알고리즘을 제시하였다. 특히, 링크기반동적표지를 적용함으로써 수단간 환승시 발생되는 환승이동, 환승대기 및 기타 환승행태를 용이하게 모사하면서 최적해를 도출하도록 하였다. 최적식과 함께 제시된 알고리즘은 복잡도계산을 통해 효율성을 살펴보았으며. 버스와 지하철로 구성된 소규모 가상네트워크에 대해 적용해 봄으로써 알고리즘의 검증 및 활용성을 검토해 보았다.

• Management Science and Financial Engineering
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• 제10권1호
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• pp.53-75
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• 2004

Most existing studies on time-dependent networks have been focused on finding a minimum delay path given a departure time at the origin. There, however, frequently happens a situation where users can select any departure time in a certain time interval and want to spend as little time as possible on traveling the networks. In that case. the delay spent on traveling networks depends on not only paths but also the actual departure time at the origin. In this paper, we propose a new problem in time-dependent networks whose objective is to find an optimal departure time given possible departure time interval at the origin. From the optimal departure time, we can obtain a path with minimum delay among all paths for possible departure times at the origin. In addition, we present an algorithm for finding an optimal departure time by enumerating trees which remain shortest path tree for a certain time interval.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 추계학술대회 논문집
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• pp.109-112
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• 2000

This paper presents an analytical study that can predict the path-dependent forming limits for bilinear strain paths. To predict the forming limit diagrams(FLD), the analytical procedure was performed within the framework of Marciniak and Kuczynski approach by introducing the effect of the existence of strain gradient over the stretching punch. The predicted path-dependent forming limits of an anisotropic sheet were compared with the published experimental results. It was found that the predicted path-dependent forming limits were in good agreement with the experimental data.

• 한국농공학회지
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• 제38권2호
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• pp.133-144
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• 1996

To get accurate results, the realistic stress-strain relationships of soils are dependent on a number of factors such as soil types, density, stress levels and stress path. Such attempts are continuously being made by the developement of analytical models for soils incorporating all such factors. Isotropic compression-expansion test and a series of drained conventional triaxial tests with several stress path for Baekma river sand were performed to investigate parameters characteristics of Lade's single work hardening model dependant on the stress path. Using the computer program based on the regression analysis, the values of parameters for the model were determined. In conclusion, the parameters of Lade's model are little influenced by the stress paths. Though yield criterion parameters ( h, ${\alpha}$a) are much influenced by stress level and stress path, the parameters don't have influence on stress-strain behavior.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.759-762
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• 2005

Recently, Intelligent Transportation System(ITS) has been applied to satisfy increasing traffic demand every year and to solve many traffic problems. Especially, Advanced Traveller Information System(ATIS) is a transportation system to optimize the trip of each other vehicle. It is important to provide the driver with quick and comfortable path from source to destination. However, it is difficult to provide a shortest path in a road network with dynamic cost. Because the existing research has a static cost. Therefore, in this paper we propose an operator for searching traffic dependent shortest path. The proposed operator finds the shortest path from source to destination using a current time cost and a difference cost of past time cost. Such a method can be applied to the road status with time. Also, we can expect a predicted arrival time as well as the shortest path from source to destination. It can be applied to efficiently application service as ITS and have the advantages of using the road efficiently, reducing the distribution cost, preparing an emergency quickly, reducing the trip time, and reducing an environmental pollution owing to the saving the fuel.

• 한국지반공학회논문집
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• 제19권1호
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• pp.143-150
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• 2003

과압밀점토의 응력-변형 거동에 중요한 영향을 미치는 변형률 속도에 관하여 다루었다. 본 연구에서는 응력경로 회전각, 과압밀비 그리고 접근길이를 포함한 응력이력과 재하속도 이력 및 재하속도를 포함한 시간이력을 변화시켜 압밀-배수 응력경로 삼축 실험을 수행하였다. 실험 결과 모든 영향인자에 대하여 시간이 증가할수록 변형률 속도 역시 증가하였다. 또한, 회전각의 정의에 따라 상이한 변형률 속도의 값을 보였고, 과압밀비와 재하속도가 증가할수록 변형률 속도 역시 증가하였다. 응력이력에서는 응력-변형 거동과 변형률 속도간의 상관성이 존재하였지만 시간이력에서는 응력-변형-변형률 속도의 상관성을 보이지 않았다.

• 한국농공학회지
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• 제40권6호
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• pp.95-103
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• 1998

Solutions of geotechnical engineering problems require calculation of deformation and stresses during various stages of loading. Powerful numerical methods are available to make such calculation even for complicated problems. To get accurate results, realistic stress-strain relationships of soil are dependent on a number of factors such as soil type, density, stress level and stress path. Attempts are continuously being made to develope analytical models for soils incorporating all such factors. The nature of stress-path dependency, the principle that governs deformations in sand, and the use of Lade's single work-hardening model for predicting sand response for a variety of stress-paths have been investigated and are examined. The test results and the analyses presented show that under some conditions sand exhibits stress-path dependent behavior. The strains calculated from Lade's single work-hardening model are in reasonable agreement with those measured, but some discrepancies occur. The largest difference between measured and calculated strains occurs for proportional loading with increasing stresses and for stress-path directions.