• Journal of Korean Society of Industrial and Systems Engineering
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• v.18 no.34
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• pp.129-137
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• 1995

Recently the recognition of Logistics becomes important to enterprises as a means for improving their competition, but the Korea enterpries falls for far behind in management techniques for analyzing realities and problems in the logistic compare to the advanced countries. In describing a distribution network, we have stated that it is basically a system or a set of locations that ship, receive or store material plus the routes that connect these locations. Using a Dynamic Programming on logistics, we can decrease the inventory level and increase the service level on logistics and the management performance.

• IE interfaces
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• v.14 no.1
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• pp.30-38
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• 2001

Logistics network management has become one of the most important sources of competitive advantage regarding logistics cost and customer service in numerous business segments. Logistics network simulation is a powerful analysis method for designing and planning the logistics network optimally in an integrated way. This paper introduces a logistics network simulator, LONSIM, developed by author. LONSIM deploys a mix of simulation and optimization functions to model and analysis logistics network issues such as facility location, inventory policy, manufacturing policy, transportation mode, warehouse assignment, supplier assignment, order processing priority rule, and vehicle routes. LONSIM is built with AweSim 2.1 and Visual Basic 6.0, and executed in windows environment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.1
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• pp.79-89
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• 2023

The inventory of many materials requires a large storage space, and the longer the storage period, the higher the potential maintenance cost. When materials are stored on a construction site, there are also concerns about safety due to the reduction of room for movement and working. On the other hand, construction sites that do not store materials have insufficient inventory, making it difficult to respond to demands such as sudden design changes. Ordering materials is then subject to delays and extra costs. Although securing an appropriate amount of inventory is important, in many cases, material management on a construction site depends on the experience of the site manager, so a reasonable material inventory management plan that reflects the construction conditions of a site is required. This study proposes an economical material management method by reflecting variables such as the status of the preceding and following activities, site size, material delivery cost, timing of an order, and quantity of orders. To this end, we set the appropriate inventory amount while adjusting related activities in the activity network, using float time for each activity, the size of the yard, and the order quantity as the main variables, and applied a genetic algorithm to this process to suggest the optimal order timing and order quantity. The material delivery cost derived from the results is set as a fitness index and the efficiency of inventory management was verified through a case application.

• Journal of Korean Society of Transportation
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• v.13 no.2
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• pp.43-58
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• 1995

This paper discusses some of the results of investigation of railroad-highway grade crossing accidents and accident-related inventory information that was collected from the Pusan District Office of the Korean National Railroads. Established statistical techniques were applied to tabulated data to obtain an accident prediction equation that estimates the expected probability of accidents at each crossing under various grade crossing situations. It was found that the most significant factor that influences the railroad crossing accidents was flagger. The other factors were train and traffic volumes, number of tracks. crossing angle, maximum timetable train speed, algebraic grade difference, and lighting facility. No significant effects was identified with railroad crossing gates. The results of the analysis and the uses of the prediction equation for the development of warrants for safety improvements are also discussed.

• Journal of Korean Institute of Industrial Engineers
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• v.35 no.1
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• pp.92-100
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• 2009

Today international trade through maritime transportation is significantly increasing. Due to this increase, shipping companies are faced with problems concerning the repositioning of empty containers from import dominant ports. The liner shipping service network has been provided to transport containers which load customers' freights. Container ships are moved on the liner shipping service network by observing the predetermined route and transportation time. This research deals with the empty containers distribution problem considering the container ship route. A mathematical model based on the mixed integer program has been introduced in this study. The objective is to minimize the total relevant costs of empty containers such as handling, leasing, and inventory holding, etc. Due to the complexity of the problem, a genetic algorithm has been suggested to solve large sized problems within a reasonable time. Numerical experiments have been conducted to show the efficiency of the genetic algorithm.

• IE interfaces
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• v.14 no.3
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• pp.255-262
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• 2001

Containerization of cargo transportation has been norm in the word wide maritime services, but containerized trades are typically unbalanced in terms of the number of inbound and outbound containers. Therefore it is critical for shipping companies to find operating policy such as the repositioning of empty containers or replenishing of short-term leasing containers from leasing companies to satisfy the freighter's demands of containers. This paper develops a simulation model using ARENA to establish shipping company's operational policy to relocate and replenish empty containers. Furthermore, this study proposes simple and heuristic empty container repositioning rules to minimize the relevant cost in terms of leasing, repositioning, and inventory holding costs.

• Journal of the Korean Operations Research and Management Science Society
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• v.6 no.1
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• pp.57-64
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• 1981

The continuous increase of crude oil consumption has struck great impact into the world economy, When we consider disadvantageous articles in contract for oil import, it would be desirable to import in batch the total quantity of crude oil contracted, but which is not available under the present situation which has many constraints This paper treats of the ways to deliver the crude oil in a given period so as to maximize the profit derived from the sales of oil products, To do this we should consider the prices of crude oil and oil products, inventory cost, transportation cost, oil refinement cost, and fluctuations of these parameters in a given period. The case of Korea Oil Corporation is treated in this paper to generalize the problem of crude oil transportation from Middle East and formulated in a mathematical programming. This programming is transformed into Dynamic Programming through specifing states, stages, payoffs, and recursive function. To clarify these procedure and methods, the case of Korea Oil Corporation is dealt with again and demonstrated in detail.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.14-20
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• 2003

Supply chain is the link that moves products between suppliers, manufactures, wholesalers, distribution, retailers and ended consumers. Supply chain management(SCM) is a way to supervise the flow of products, materials and information as they move along the supply chain. In the recent years, Most of the companies are in a hurry the introduction of SCM to obtain international competitiveness. The goal of SCM is to optimize the supply chain, which can not only reduce inventories, but may also create a higher profit margin for finished goods by giving customers exactly what they want. There are four major decision areas (location, production, inventory, transportation) in supply chain management, and there are both strategic and operational elements in each of these decision areas. This paper is concerned with the integrated production planning problem including not only the production cost but also the transportation cost in supply chains, and an efficient algorithm using genetic algorithm and quickest path method is presented to solve the problem.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.55 no.4
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• pp.176-182
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• 2006

In this paper, we explore a novel transportation container in the marine terminals. The container includes Smart Tag embedded with radio frequency(RF) chips, which is used to access information about productions and possibly incorporated with GPS systems for integrated managements of them. The proposed mechanism is valuable for decreasing cost, increasing satisfaction of customers, and preventing economic loss due to production missing, thus increase of economic efficiency is highly anticipated. Consequently, accurate and proficient management is considerably accomplished in overall procedures of inventory and currency by means of the proposed systems.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.26 no.1
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• pp.85-94
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• 2003

In this paper, a mathematical model is developed for economic design of multi-stage distribution system that consists of factory, central distribution centers, local distribution centers and retailers. The retailers are supplied products from different stage suppliers according to order size. The retailers are supplied products from factory if demand amount is large, central distribution center if medium, local distribution center if small. The economic design is to determine the economic size of facility factors that consist of distribution system. The cost factors are transportation cost from supply places to demand places, handling cost at distribution centers and inventory holding cost at retailers. It is to determine the transportation route of each retailer, the size and number of the vehicle at factory and distribution centers, the handling amount at distribution centers in order to minimize the total costs. The mathematical model is represented, the solution procedure is developed, and a numerical example is shown.