• Journal of the Korean Operations Research and Management Science Society
• /
• v.31 no.3
• /
• pp.81-96
• /
• 2006

We consider a rental company that dynamically manages Its capacity level through capacity addition and return While serving customer with its own capacity, the company expands its capacity by renting items from an outside source so that it can avoid lost opportunities of rental which occur when stock is not sufficient. If stock becomes sufficiently large enough to cope with demands, the company returns expanded capacity to the outside source. Formulating the model into a Markov decision problem, we identify an optimal capacity management Policy which states when the company should expand its capacity and when it should return expanded capacity after capacity addition. Since it is intractable to analytically find the optimal capacity management policy and the optimal size of capacity expansion, we present a numerical procedure that finds these optimal values based on the value iteration method. Numerical analysis is implemented and we observe monotonic properties of the optimal performance measures by system parameters, which are meaningful in developing effective heuristic policies.

• Korean Management Science Review
• /
• v.30 no.3
• /
• pp.71-79
• /
• 2013

This paper investigates and selects the areas that need to be improved in R&D and production management of small and medium size companies. The study on the capability of R&D and production management shows that the areas for evaluating of the R&D and production management levels are composed of 8 elements : R&D resource, R&D support and experience, long-term operations strategy, intermediate range planning, short-term planning, subcontractor management, logistics and inventory management, and quality management. The investigation of the gap between the importance of the areas and the capability of SMEs shows that the most important things are to consolidate supply chain, to improve product and process competitiveness using quality improvement, and to enhance production management through sophisticated short-term planning. The detailed analysis also shows that the areas that need to be improved depend on the size and sales of the company.

• Journal of the military operations research society of Korea
• /
• v.31 no.1
• /
• pp.58-72
• /
• 2005

RFID(Radio Frequency Identification) is one of key technologies in ubiquitous computing. RFID system comprises tag, reader, and computer application. The tag is a small electronic chip, which is attached to a thing such as item, pallet, container. The reader has an tiny antenna obtaining the identification information of the things by radio frequency, and provides the information to the computer application for a business. In this paper we have proposed the military application of RFID and its implementation policy for the Korean armed forces. We believe that The principle application area would be logistics TAV(total asset visibility) and resource management, and the implementation should be achieved step by step considering the advancement of RFID technology and government policy.

• Journal of Korea Port Economic Association
• /
• v.22 no.1
• /
• pp.175-198
• /
• 2006

This paper presents a network capacity model that can be used as an analytical tool for strategic planning and resource allocation for multimodal transportation systems. In the context of freight transportation, the multimodal network capacity problem (MNCP) is formulated as a mathematical model of nonlinear bi-level optimization problem. Given network configuration and freight demand for multiple origin-destination pairs, the MNCP model is designed to determine the maximum flow that the network can accommodate. To solve the MNCP, a heuristic solution algorithm is developed on the basis of a linear approximation method. A hypothetical exercise shows that the MNCP model and solution algorithm can be successfully implemented and applied to not only estimate the capacity of multimodal network, but also to identify the capacity gaps over all individual facilities in the network, including intermodal facilities. Transportation agencies and planners would benefit from the MNCP model in identifying investment priorities and thus developing sustainable transportation systems in a manner that considers all feasible modes as well as low-cost capacity improvements.

• IE interfaces
• /
• v.20 no.1
• /
• pp.21-32
• /
• 2007

This paper deals with the simulation model for A-Mart logistic center design and operations. In developed simulation model, receiving docks, conveyor sorter, conveyor system, shipping docks, material handling devices and manual sorting stations are considered. Three types of cargo such as transfer center cargo, distribution center cargo and supermarket cargo are considered. The simulation model and process animation are developed using the simulation package ARENA. Among various design and operation alternatives consisting of the number of workers of receiving dock, allocation of receiving docks by cargo types, conveyor sorter velocity, the number of folk-lift, the number of manual sorting operators and overall layout, the best alternatives of each subsystem are selected by simulation analysis. The major performance measures such as sorter throughput, utilization of operators at each station, receiving docks utilization and folk-lift utilization are considered for the alternative evaluation.

• IE interfaces
• /
• v.19 no.1
• /
• pp.1-8
• /
• 2006

The mobile communication network has to offer good quality of services (QoS), high capacity, and more coverage at a lower cost. However, with the increase of cellular user, the shortage of capacity due to unbalanced call distribution and lack of QoS are common. This paper deals with dynamic sectorization for efficient resource management to solve load unbalancing among microcells in CDMA (Code Division Multiple Access) microcellular system. Dynamic load balancing can be effected by grouping micro-cells properly and grouping can be developed through a routing mechanism. Therefore, we use ants and their routes to choose the optimum grouping of micro-cells into sectors using Multiple Ant Colony System (MACS)in this paper.

• Industrial Engineering and Management Systems
• /
• v.11 no.1
• /
• pp.103-113
• /
• 2012

A yard in a container terminal is a temporary storage space before containers are loaded onto the target vessel or delivered to consignees. For improving the utilization of the space in the yard and the efficiency of loading and discharging operations, it is important that operation plans must be carefully constructed in advance. A heuristic method is suggested to solve operation space planning problems considering workloads on handling equipment as well as space availabilities. The operation plans in this paper includes quay crane (QC) schedules and space plans for multiple vessels considering the workload in the container yard of container terminals. This paper evaluates the effectiveness of a space planning method and the performance of a new QC scheduling method using a simulation model.

• International Journal of Advanced Culture Technology
• /
• v.9 no.3
• /
• pp.23-33
• /
• 2021

"China's Western Development Policy" has brought multiple opportunities to the development of tourism in Southwest China including Sichuan, Guizhou, Yunnan, Chongqing and Tibet. The 4 provinces and 1 municipality overall show a certain degree of accumulation effect and coordinated development in tourism due to their location, traffic and traditional economic cooperation. This study takes the Southwest China as the research object and utilized the spatial dislocation model and the tourism spatial misalignment index to estimate the mismatch degree between tourism resources and tourism income among provinces and try to find out the internal reason background. The results show that each of the five provinces has its own advantages in index of economy, tourism resources, human resource, and transportation, leading to differences in the center of gravity of the entire region in all aspects. In view of the results of spatial dislocation analysis, suggestions for improvement and optimization are put forward to promote the high-quality development of tourism in Southwest region. development.

• Journal of the Korea Society for Simulation
• /
• v.27 no.2
• /
• pp.125-137
• /
• 2018

Simulations have been used to evaluate the efficiency of logistics or manufacturing systems and predict the outcomes of the systems. New simulation models are needed to evaluate new alternative plants and layouts during the resource design process. Although it is easy to handle minor changes in parameters by modifying a simulation model, it takes considerable time and effort for simulation modelers to alter the layout, which involves changes in many simulation sub-models. Therefore, this study proposes a method to transfer information in AutoCAD layout to the simulation model automatically. This study also defines a standard document as an Excel Form, and suggests a method to transfer information on the basic layouts, processes, resources, and workers to a simulation model automatically. A simulation tool, called Tecnomatix Plant Simulation 9.0, was used for this study. The proposed approach in this study was applied to a semiconductor wafer factory for a case study.

• Journal of Environmental Science International
• /
• v.26 no.8
• /
• pp.977-991
• /
• 2017

The purpose of this study is to establish common indicators that constitute a "low-carbon green city" and determine their priorities from the perspective of Incheon Metropolitan City with a view to help develop its climate change strategy strategic city. Several major cities, domestic and overseas, were benchmarked to come up with preliminary indicators consisting of six areas, twenty two planning factors, and 74 indicators. In order to evaluate the validity and relevance of preliminary indicators, expert FGI (Focus Group Interview) was conducted that changed the numbers of final indicators to six areas, twenty two planning factors, and 82 indicators. Finally, AHP (Analytic Hierarchy Process) was conducted to assign relative importance (i.e. weights) to each indicator. Through the layering process of AHP, the upper category of "field" and lower category of "planning factors" were set up as policy prerequisites for constructing a low-carbon green city (6 fields, 22 planning factors). The AHP results for the first level (fields), green city space was ranked first, followed by energy and resource circulation, green traffic, ecological preservation, green logistics, and governance. Among all planning factors, land use, energy efficiency, traffic system improvement, location planning, securing of ecological area, efficiency of logistics, and cooperative organization showed the highest priorities.