• Proceedings of the KOR-KST Conference
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• 1996.06a
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• pp.43-49
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• 1996

In this paper, the south-north railway transportation demand and the present situation of Huning line(from Shanghai to Nanjing) are analyzed, and the important significance and the simulation, we also discuss the transportation organization plans, the transportation capacities, the stage by stage implement programs and the comprehensive social economic benefits on the condition of raising the train speed on Huning line.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.44-51
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• 2019

Designing sophisticate ship structures that satisfy several design criteria simultaneously with minimum weight and cost is an important engineering issue. For a ship structure composed of a shell and stiffeners, this issue is more serious because their mutual effect has to be addressed. In this study, a two-stage optimization method is proposed for the conceptual design of stiffeners in a ship's prow. In the first stage, a topology optimization method is used to determine a potential stiffener distribution based on the optimal results, whereupon stiffeners are constructed according to stiffener generative theory and the material distribution. In the second stage, size optimization is conducted to optimize the plate and stiffener sections simultaneously based on a parametric model. A final analysis model of the ship-prow structure is presented to assess the validity of this method. The analysis results show that the two-stage optimization method is effective for stiffener conceptual design, which provides a reference for designing actual stiffeners for ship hulls.

• Journal of Navigation and Port Research
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• v.33 no.4
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• pp.271-275
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• 2009

A strategic decision making on location selection for product transportation includes many tangible and untangible factors. To choose the best locations is a difficult job in the sense that objectives usually conflict with each other. In this paper, we consider a multi stage multi criteria transshipment problem with different types of items to be transported from the sources to the destination points. For the optimization of the problem, a goal programming formulation will be presented in which the location selection for each product type will be determined under the multi objective criteria. In the study, we generalize the transshipment model with a variety of product types and finite number of different intermediate nodes between origins and destinations. For the selection of the criteria we selected the costs(fixed cost and transportation cost), location numbers, and unsatisfied demand for each type of products in multi stage transportation, which are the main goals in transshipment modelling problems. The related conditions are also modelled through linear formats.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.43
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• pp.139-144
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• 1997

The objective of this study is to establish an actual optimization strategy for the traditional multi-stage distribution system which consists of factory warehouse, central distribution warehouse, and regional distribution warehouse under the basic assumption of distribution system. A minimization algorithm of total operating cost in a multi-stage distribution system was developed by expanding the previously existing algorithm through consideration of additional transportation environment. Alternative non-linear transportation costs for the same travel distance can be applied for the multi-stage distribution system by estimating the corresponding characteristic values through the collection of the actual data representing the change of transportation circumstances.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.3
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• pp.261-272
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• 2014

Home appliances go through a couple of packaging stages from the plant to consumers. The primary packaging, inner packaging for each part, happens for protection after products leave the plant. The secondary packaging happens in the unit of product, ensuring cushioning packaging to protect products from movement. The final tertiary packaging is for transportation and delivery. Each stage of product packaging, however, costs a lot of money because of disposable packaging materials used in each stage including vinyl, tapes, Styrofoam, and corrugated cardboards. Discarded packaging materials also cause environmental problems. In an effort to come up with a measure to solve those problems, this study proposed a plan to minimize logistics costs with semi-permanent packaging materials to replace disposable ones including Styrofoam, vinyl, and corrugated cardboards in the stages of inner packaging, cushioning packaging, product unit-based packaging, and transportation. The study also developed a model to cut down logistics costs by reducing various packaging stages including the primary, secondary, and tertiary stage only to the secondary one through module-type products instead of the transportation- and delivery-type ones, as well as demonstrated the excellence of the study through numerical analysis.

• Journal of the Korean Operations Research and Management Science Society
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• v.34 no.1
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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.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.3
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• pp.1-11
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• 2016

The present study aims to evaluate transfer resistance factors in railway stations and draw new implications. The data used for the model estimation are RP (revealed preference) data and SP (stated preference) data. Two types of models were used for the analysis: integration model which combined line-haul stage, transfer stage and shuttle stage and separation model which assessed the three stages separately. The results revealed that while bulk freight shippers mainly focused on line-haul stage, they put emphasis on transfer stage as well. It's especially notable that transfer stage was considered more important than shuttle stage. Therefore, in future transportation policies concerning rail freight, it would be crucial not only to enhance the competitiveness of line-haul stage but also make improvements in transfer stage regarding railway stations.

• Korean Management Science Review
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• v.27 no.3
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• pp.15-31
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• 2010

We consider a reverse logistics network design problem for recycling. The problem consists of three stages of transportation. In the first stage products are transported from retrieval centers to disassembly centers. In the second stage disassembled modules are transported from disassembly centers to processing centers. Finally, in the third stage modules are transported from either processing centers or a supplier to a manufacturer, a recycling site, or a disposal site. The objective is to design a network which minimizes the total transportation cost. We design a cooperative coevolutionary algorithm to solve the problem. First, the problem is decomposed into three subproblems each of which corresponds to a stage of transportation. For subproblems 1 and 2, a population of chromosomes is constructed. Each chromosome in the population is coded as a permutation of integers and an algorithm which decodes a chromosome is suggested. For subproblem 3, an heuristic algorithm is utilized. Then, a performance evaluation procedure is suggested which combines the chromosomes from each of two populations and the heuristic algorithm for subproblem 3. An experiment was carried out using test problems. The experiments showed that the cooperative coevolutionary algorithm generally tends to show better performances than the previous genetic algorithm as the problem size gets larger.

• Structural Engineering and Mechanics
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• v.54 no.2
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• pp.199-219
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• 2015

This paper presents the non-destructive evaluation of a high-speed railway bridge using train-induced strain responses. Based on the train-track-bridge interaction analysis, the strain responses of a high-speed railway bridge under moving trains with different operation status could be calculated. The train induced strain responses could be divided into two parts: the force vibration stage and the free vibration stage. The strain-displacement relationship is analysed and used for deriving critical displacements from theoretical stain measurements at a forced vibration stage. The derived displacements would be suitable for the condition assessment of the bridge through design specifications defined indexes and would show certain limits to the practical application. Thus, the damage identification of high-speed railways, such as the stiffness degradation location, needs to be done by comparing the measured strain response under moving trains in different states because the vehicle types of high-speed railway are relatively clear and definite. The monitored strain responses at the free vibration stage, after trains pass through the bridge, would be used for identifying the strain modes. The relationship between and the degradation degree and the strain mode shapes shows certain rules for the widely used simply supported beam bridges. The numerical simulation proves simple and effective for the proposed method to locate and quantify the stiffness degradation.

• Smart Structures and Systems
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• v.21 no.5
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• pp.623-635
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• 2018

In order to study the mechanical behavior of shield tunnel segments during assembly stage, the in-situ tests and FDM numerical simulation were conducted based on the Foguan Shiziyang Tunnel with large cross-section. Analysis for the load state of the assembling segments in different assembly steps as well as the investigation for the changing of inner forces and longitudinal stress of segments with assembling steps were carried out in this paper. By comparing the tested results with the simulated results, the conclusions and suggestions could be drawn as follows: (1) It is the most significant for the effects on axial force and bending moment caused by the assembly of adjacent segment, followed by the insertion of key segment while the effects in the other assembly steps are relative smaller. With the increasing value of axial force, the negative bending moment turns into positive and remains increasing in most monitored sections, while the bending moment of segment B1and B6 are negative and keeping increasing; (2) The closer the monitored section to the adjacent segments or the key segment, the more significant the internal forces response, and the monitored effects of key segment insertion are more obvious than that of calculation; (3) The axial forces are all in compression during assembling and the monitored values are about 1.5~1.75 times larger than the calculated values, and the monitored values of bending moment are about 2 times the numerical calculation. The bending moment is more sensitive to the segments assembly process compared with axial force, and it will result in the large bending moment of segments during assembling when the construction parameters are not suitable or the assembly error is too large. However, the internal forces in assembly stage are less than those in normal service stage; (4) The distribution of longitudinal stress has strong influence on the changing of the internal forces. The segment side surface and intrados in the middle of two adjacent jacks are the crack-sensitive positions in the early assembly stage, and subsequently segment corners far away from the jacks become the crack-sensitive parts either.