• Journal of Korean Port Research
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• v.10 no.2
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• pp.51-59
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• 1996

The management of liner shipping company is an extremely complex activities, especially if a company aims to simultaneously optimize the cost and service of the company's operations in a competitive environment. This paper investigates the control process of containers in a typical container liner shipping and proposes day by day operational model for empty container control in the maritime container transportation system. We proposed a linear programming model for empty container control in container liner shipping and the computational results show utilities of the model.

• Journal of Forest and Environmental Science
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• v.32 no.2
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• pp.189-195
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• 2016

Logging equipment and method have a major influence on harvesting productivity and cost. This study investigated the productivity and operational costs of tree-length cable yarding system using HAM300, a domestically developed tower yarder. We tested HAM300 for thinning operation in Pinus densiflora stands at Gangreung, Gangwon-do on April, 2014. To assess the productivity we conducted time study for each stage of the operation. When the average time/cycle was examined for each stage of the operation, the longest was for yarding (241 sec), followed by delimbing (237 sec), felling (153 sec), and processing (103 sec). Furthermore, productivity for felling was $8.6m^3/hr$, followed by delimbing ($5.1m^3/hr$), yarding ($3.5m^3/hr$), and processing ($8.1m^3/hr$). The total cost for the tree-length logging system was $58,446won/m^3$, of which the majority was incurred by the yarding cost at $46,217won/m^3$ (79.3%), whereas the lowest cost was for felling at $2,359won/m^3$ (4.1%). We suggest that it is necessary to foster specialized operators and provide training in operating the tower yarder thereby implementing efficient harvesting system resulting from low-cost yarding.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.4
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• pp.460-466
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• 2018

With the development of information technology, the scale of computer software system is constantly expanding. Reliability and cost of software development have a great impact on software quality. In this study, based on the software failure interval time data, a comparative analysis was performed on the characteristics of the software development cost model based on the lifetime distribution following the Type-2 Gumbel and Erlang distribution in the NHPP model. As a result, the trends of the cost curves for the Go-Okumoto model and the proposed Erlang model and the Type-2 Gumble model both decreased in the initial stage and gradually increased in the latter half of the failure time. Also, Comparing the Erlang model with the Type-2 Gumble model, we found that the Erlang model is faster and more cost-effective at launch. Through this study, Software operators should remove possible defects from the testing phase rather than the operational phase to reduce defects after the software release date, it is expected to be able to study the prior information needed to understand the characteristic of software development cost.

• Journal of Korea Society of Industrial Information Systems
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• v.23 no.4
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• pp.69-79
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• 2018

We performs the cost-benefit analysis, an economical analysis technique, to measure the effect of a shared public supercomputer. The costs of two given alternatives, to share the public supercomputer in a national center and to employ their own supercomputers in the organizations under the necessity, will be estimated and compared for decision making. In the case of sharing, we can simply predict the cost based on the results of the previous public supercomputer. The cost of individual introduction, however, is almost unpredictable since it has a remarkable variability due to the required system performances, locations, human factor, and so on. Accordingly, an objective and valid method to estimate the cost of individual cases will be proposed in this research. Finally, we analyze the economic effect of operating public supercomputer by comparing the sharing cost with that of the individual employs. The results of analysis confirms that the sharing public supercomputer will reduce the operational cost about 10.3 billion won annually compared with the individual introduction. Accordingly, it is expected that the sharing public supercomputer will bring a considerable economical effect.

• Journal of the Korean Society for Railway
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• v.15 no.2
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• pp.97-103
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• 2012

Composite honeycomb sandwich plate is light and strong. It is easy to produce. It began to be applied to the bodyshell of rolling stock. Generally, weight saving amounts to 27%. However, the material cost of it is much higher than that of aluminum extrusion profile, which prevents popular use of it for bodyshell. In this paper, manufacturing processes of two light materials were compared to investigate cost impact. After cost breakdown was defined, economics of two materials was analyzed using the previous cost data. Easy production of composite bodyshell could compensate for higher material cost. Mass production of composite bodyshell can make the equipment cost lower for the composite bodyshell so that it may have strong competitiveness to the aluminum bodyshell. Operational energy saving due to weight reduction was also presented referring to the actual statistical data in a metro line.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.93-94
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• 2021

The Korean government has invested a tremendous amount of money in the last 10 years to build large public research infrastructures (LPRI). For efficient operation and maintenance of LPRI built with expensive equipment and professional engineers, reasonable budget needs to be allocated. However, it is difficult to fulfill sustainable operation and maintenance (O&M) because there is no standard on budgeting for efficient LPRI operation, including expensive equipment and manpower allocation. There have been a lot of cost assessment studies regarding O&M of high-demand facilities such as hospitals, hotels and residential buildings, but a very few on sustainable O&M of LPRI. Therefore, mid/long-term budget establishment plans for efficient LPRI O&M are required from the initial planning stage and a cost assessment model to support the plans should be developed. The objective of this paper is to propose a cost assessment model for sustainable operation and maintenance of large public research infrastructures. To do so, actual O&M data of 6 LPRI types in operation are collected, and regression analysis model (RAM) is used for development and evaluation a cost assessment model. The study result will support sustainable operation of LPRI from a business perspective and be used as basic data for continuous development of cost assessment models to establish budgets for LPRI operation from an academic perspective.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1147-1152
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• 2004

Switched Reluctance Motors have an inexpensive, intrinsic simplicity and low cost that makes them well suited to home appliance and office applications. However the motor suffering with necessity of shaft position sensor, lead to non-linearity of operations. Further, the involvement of static converters deteriorates the operational power factor. Implementation of a sensorless algorithm, can remove the need of position sensors. Also, the drive includes a compact power factor control in the input stage by implementing Zero Current Switching Quasi-Resonant Boost Technology. This paper presented, aims at optimized low line current distortion, high power factor, low cost and a shaft position sensorless Switched Reluctance Motor drive.

• Journal of the Korean Society of Systems Engineering
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• v.13 no.2
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• pp.1-8
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• 2017

The Core in Weapon system R&D is to realize the user required capabilities in limited schedule and cost. Therefore, the design of weapon system focuses to functional design for realization of requirement capabilities. However, the weapon system should not only basically bring the confidence to friendly forces bring fear to enemy forces to maximize the operational effectiveness of weapon systems and we consider the exterior design as the important factor to compete with foreign systems in international defense market besides capabilities and cost. For that reason, we made study case about the visual design decision process applied to the LVT(light tactical vehicle) project which was recent successful deployment among the many R&D projects of auto industry. Based on this case, this study suggests the necessity of the exterior design decision process the maneuver weapon system is developed.

• Journal of Korean Institute of Industrial Engineers
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• v.35 no.1
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• pp.58-72
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• 2009

The main activities of container terminals are to load container freights to vessels, discharge them from vessels, and store them in the storage yard. Container terminals make many operational plans to execute these functions effectively. If the plans do not consider enough the loads of related resources, they may have low actualities. This study discusses the optimal yard planning model which considers various resources, such as the storage yard, yard cranes, internal vehicles, and travel lanes, in container terminals. The model determines the groups and amounts of containers which are stored in each storage block by using the resource profile. The yard planning problem is represented to the multi-commodity minimal cost flow problem and is formulated to the linear programming model. In order to explain the application of the mathematical model, the numerical examples are presented. Additionally, the relationship between the average load ratio and the relocation ratio is discussed.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.686-691
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• 2005

We are concerned with the question of servicing warranties for repairable items. During the warranty period, each time an item fails the manufacturer has the obligation to restore the item to operational condition either by repairing the item or by replacing it by a new item. In this paper, we consider the repair-replacement strategies based on the condition of the failed item. For products with phase-type lifetime distributions where the phases represent the condition of the item, we develop algorithms to determine the expected cost of servicing a warranty and use it in making the repair-replacement decision. Illustrative numerical examples are presented. We also propose a dynamic strategy by taking the expected remaining warranty cost into consideration.