• Journal of the Korea Society for Simulation
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• v.15 no.4
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• pp.143-151
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• 2006

This paper deals with the simulation model for design and operations of A-Mart logistic center for low temperature products. In developed simulation model, receiving docks, digital classification system (DCS), shipping docks, material handling devices and manual sorting stations are considered. Five types of cargo such as fruits, palletized fruits, delicatessen and fisheries, vegetables and refrigerated cargoes 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, DCS capacity, 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 DCS throughput, utilization of operators at each station, receiving docks utilization and folk-lift utilization are considered for the alternative evaluation.

• Journal of Navigation and Port Research
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• v.27 no.1
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• pp.31-40
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• 2003

Because yard monitoring system is a part of real-time operation system and yard planning system, most planers, in container terminal, Busan Port, can not consider real-time and exact yard situation and container information such as position of equipments or movement of container with current planning system when export yard planning os established. Therefore, many planers recognize the limit of current planning system and try to find the solution to get over it. The reason of this, heuristic algorithms for the export yard the limit of current planning ,operating on monitoring system, are suggested and integrated export yard planning system is designed and developed in this paper.

• Journal of Korea Port Economic Association
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• v.33 no.2
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• pp.83-96
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• 2017

As a way to address global warming, among the renewable energy sources, there have been heavy investments worldwide for the development of offshore wind farms. However, such development has a drawback: investment costs are higher than those for onshore wind farms due to required operations such as offshore transportation and installation. In particular, delays in installation due to adverse maritime weather conditions are factors that affect the economics of offshore wind farms' operation. Therefore, in this study, we analyze the optimal schedule of the construction of an offshore wind farm from a macro perspective by considering the weather conditions in Korea. For this purpose, we develop a mathematical model and apply it to a 2.5 GW offshore wind farm project on the southwestern coast of the country. We use data from the Korea Meteorological Agency for maritime weather conditions and attempt to reflect the actual input data based on precedent cases overseas. The results show that it takes 6 months to install 35 offshore wind turbines. More specifically, it is pointed out that it is possible to minimize costs by not working in winter.

• Journal of Global Scholars of Marketing Science
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• v.11
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• pp.183-207
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• 2003

The human resource management is a very important thing to an airline call center. It may lead the call center to success or fail. The call center managers have to make appropriate decisions how many persons are inputted into the operation for each unit time and all day. In this study, a method is suggested to get an optimal staffing for each unit time using Integer Programming. The Integer Programming model can be used to solve the efficiency problem of the call center's staffing and scheduling. And call certer manager can adopt this model into the operations of the call center without any difficulties or modifications.

• Proceedings of the CALSEC Conference
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• 1999.07a
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• pp.277-299
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• 1999

Since Chrysler Motor Co. had experienced the digital development system in the beginning of 1990's, most of leading automobile companies are trying to apply a digital information system for their own business process reengineering based upon concurrent engineering system from product planning phase. This is called as virtual DMU(Digital Mock-Up) system instead of the traditional PMU(Physical Mock-Up) system. By using the virtual prototype, all of the design requirements and system specifications can be checked, changed and optimized more quickly and more efficiently. This paper consists of five chapters for the DMU information system. In the 1$^{st}$ chapter, the principle of digital design system is suggested by using four basic modules such as product design module, process design module, manufacturing system design module and central control module. The basic scheme of DMU is introduced with the benefits of application in the chapter 2. In the chapter 3, a digital design process of new car development is explained with the detailed DMU design and design review processes. In the chapter 4, the practical DMU manufacturing techniques and applications are introduced as CAD/CAM analyses, DPA(Digital Pre-Assembly)reviews for development, production, operation and maintenance phases, digital tolerance analyses and digital factory analyses for assembling line simulation, automated robot welding processes, production jig ＆ fixtures and painting process simulation. Finally, the activities of digital design support; CAS-styling, CAE-engineering and CAT-testing are summarized for design optimization in the chapter 5. As today's automobile manufactures and related business organizations are struggling to compete in the global marketplace, they are concentrating on efficient use of DMU information system to reduce the new car development cost, to have shorten the delivery schedule and to improve product design quality. To meet the demand of those automobile industries on digital information systems, the CALS(Computer aided Acquisition and Logistics Support) and EC(Electronic Commerce)initiative has been focused as a dominant philosophy in defense ＆ commercial industries, specially automobile industries.s.

• Journal of the Korean Society for Railway
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• v.17 no.6
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• pp.466-473
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• 2014

Recently, there is has been significant interest in the allocation systems of rail track capacities with considerations of the multiple train operating companies. The system indicates both a well-defined procedure and an algorithmic method to allocate the rail track capacities. Among them, this study considers the algorithmic method to derive the optimal timetable for the trains, which the companies propose together with their arrival and departure times at each station. However, most studies have focused on the adjustment of the departure and arrival times without conflicts, which could result in incompatible allocations with the line plan, which would result in an insufficient number of trains on each line to satisfy the demands. Our study presents a new optimization model and algorithm for the allocation problem in order to reflect the predetermined line plan. Furthermore, we provide the experimental results that were applied to the Korean high-speed railway network including the Suseo lines.

• Journal of Communications and Networks
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• v.18 no.2
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• pp.218-226
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• 2016

Coordination among users is an inevitable but time-consuming operation in wireless networks. It severely limit the system performance when the data rate is high. We present FC-MAC, a novel MAC protocol that can complete a contention within one contention slot over a joint frequency-code domain. When a node takes part in the contention, it generates randomly a contention vector (CV), which is a binary sequence of length equal to the number of available orthogonal frequency division multiplexing (OFDM) subcarriers. In FC-MAC, different user is assigned with a distinct signature (i.e., PN sequence). A node sends the signature at specific subcarriers and uses the sequence of the ON/OFF states of all subcarriers to indicate the chosen CV. Meanwhile, every node uses the redundant antennas to detect the CVs of other nodes. The node with the minimum CV becomes the winner. The experimental results show that, the collision probability of FC-MAC is as low as 0.05% when the network has 100 nodes. In comparison with IEEE 802.11, contention time is reduced by 50-80% and the throughput gain is up to 200%.

• Journal of Navigation and Port Research
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• v.31 no.1 s.117
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• pp.89-97
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• 2007

This paper presented a approach to the measurement of efficiency in container terminals in Korea. To perform this objective, it used Data envelopment analysis(DEA) which has particular applicability in the service sector. DEA as mathematical programming techniques enables relative efficiency ratings to be derived within a set of analysed units. So this paper investigated the efficiency employing DEA-CCR and DEA-BCC Model on data for 15 container terminals from 1998 through 2005. Results of this paper, suggested to some plan for operation strategy in Container terminals.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.60-61
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• 2013

One of the most important indicators for measuring service level and productivity of the port may be a demurrage rate. Currently, in the case of grain terminal of Busan North Port, demurrage rate are recognized at a very high level, in order to improve this, it is tilted more effort operational. In order to reduce the demurrage, there is a way expansion of facility of hardware, such as the replacement of aging equipment, and how manipulative assignment rules of the apparatus of the operation on the software side, such as changing the order of facility allocation. If the financial reasons are out of question, it is possible to expand to reduce the demurrage rate by operational way. Therefore this paper deals with how to operate some of the allocation rules and silo allocation rules of equipment to reduce the work hours with model and how to operate basic equipment and grain terminal of Busan North Port want to be seen by comparative analysis.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.05a
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• pp.57-58
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• 2018

As interest in the Internet of Things increases, technologies are being studied to handle information exchanged between things using the Internet of Things. Specially, as container terminals are automated, the use of the Internet of Things in the terminals increases and varies. However, the use of the Internet of Things to enhance the efficiency of the container terminal operation is insufficient. Currently, the container terminal shows that the arrival pattern of the external truck is concentrated at a particular time. This resuls in gate congestion and affects the waiting times of the truck. The damage is caused by environmental pollution problems and social problems in neighboring port areas. Therefore, in this thesis, we will analyze the causes of the external truck's waiting time problems affecting the gate congestion at container terminals and study methods to mitigate congestion under Internet of Things environment.