• Proceedings of the KSR Conference
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• 2007.11a
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• pp.784-791
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• 2007

Most operational organization and railway authority which conduct scheduled maintenance(SM) have carried out the preventive maintenance(PM) based on the information provided from supplier and manufacturer of railway system. However these activities are far away from reality and low the efficiency, it is because an appropriate methods for system selection didn't take into account for improving maintenance efficiency. Therefore, the current SM tasks and maintenance activities lead to lots of spend on the cost and time. To solve the above problem, this thesis presents new approach methodology. This proposes the criteria for reliability centered maintenance(RCM) system selection through level of quantification of each parameter, i.e, frequency, severity and maintenance cost, etc. To do this, the field operation data and information of maintenance cost are essential. As applying this methodology, we can look forward to improving efficiency of PM/SM, and reducing cost.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.11
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• pp.1547-1554
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• 1998

The object of this study was to develop an economic assessment program for the optimal design of the cogeneration systems composed of combining engine, generator, waste heat recovery exchanger, absorption chiller, and boiler, etc. The energy demand categorized by electric power, heating, cooling and water supply was determined by statistical data of the existing cogeneration systems. An economic assessment was performed by comparing the total cost of cogeneration system with that of non-cogeneration system. The total cost was evaluated by adding initial investment to operational cost considering efficiency of equipment, cost of equipment, fuel and electricity. To confirm the validity of the developed program, a hotel building with an area of $127,960m^2$ was selected, and the simulated results were compared with the measured data. The difference between the simulated and the measured values for the selected hotel building was approximately 12% for annual electric consumption.

• Journal of Agricultural Extension & Community Development
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• v.3 no.1
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• pp.43-54
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• 1996

Citrus farming become one of highly potent area for the farmer s income in the Asia region. Because of its favorable taste and distinctive aroma, attractive color, and nutritional values, market demand has increased steadily along with the income increases in the region. However, realization of the potent have been constrained due to poor orchard management, frequent occurrences of pest and diseases, and a high cost in production besides of the market failures. Cutting down of production cost should be an operational goal to obtain mope profit where marketing structure has yet been underdeveloped. The objective of this study was to provide a comparative information to those program efforts of searching comparative advantage in production. For the three countries, reduction of labor cost by reduction of chemical application frequency was recommended while pursuing further mechanization in those operation such as in pruning, harvesting and pest control. Adoption of the IPM (integrated pest management) will be useful to reduce the number of spraying chemicals with changed knowledge and attitude of the farmers.

• Journal of the military operations research society of Korea
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• v.27 no.2
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• pp.1-24
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• 2001

As the weapon systems of the 21st century are becoming more and more performance /technoloriven, it is only becoming more expensive to obtain the weapon systems. Therefore, it is absolutely vital for every nation to find a way to reduce cost objectives. As CAIV is a strategy that entails setting aggressive, yet realistic cost objectives when defining operational requirements and acquiring defense systems and managing achievement of these objectives, we believe that it is essential for us to find out what it is and how we can adopt it so that we can provide ourselves with highly capable systems that are affordable. Therefore, In this paper we will give a brief overview of CAIV that is one of the main acquisition strategies adopted by DoD of U.S. including some case studies of CAIV. Furthermore, the paper will analyze stated cost objectives in our country and suggest realistic opportunities for cost reduction.

• Journal of the Korea Society of Computer and Information
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• v.23 no.8
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• pp.133-142
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• 2018

Subway metro scheduling is one of the most important problems impacting passenger convenience today. To operate efficiently, the Seoul metro uses regular, periodic schedules for all lanes, both north and southbound. However, many past studies suggest that non-periodic scheduling would better optimize costs. Since the Seoul metro is continuously facing a deficit, adopting a non-periodic schedule may be necessary. Two objectives are presented; the first, to minimize the average passengers' waiting time, and the second, to minimize total costs, the sum of the passenger waiting time, and the operational costs. In this paper, we use passenger smart card data and a precise estimation of transfer times. To find the optimal time-table, a genetic algorithm is used to find the best solution for both objectives. Using Python 3.5 for the analysis, for the first objective, we are able to reduce the average waiting time, even when there are fewer trains. For the second objective, we are able to save about 4.5 thousand USD with six fewer trains.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.1940-1949
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• 2015

This paper presents an Enhanced Particle Swarm Optimization (EPSO) to solve short-term hydrothermal scheduling (STHS) problem with non-convex fuel cost function and a variety of operational constraints related to hydro and thermal units. The operators of the conventional PSO are dynamically controlled using exponential functions for better exploration and exploitation of the search space. The overall methodology efficiently regulates the velocity of particles during their flight and results in substantial improvement in the conventional PSO. The effectiveness of the proposed method has been tested for STHS of two standard test generating systems while considering several operational constraints like system power balance constraints, power generation limit constraints, reservoir storage volume limit constraints, water discharge rate limit constraints, water dynamic balance constraints, initial and end reservoir storage volume limit constraints, valve-point loading effect, etc. The application results show that the proposed EPSO method is capable to solve the hard combinatorial constraint optimization problems very efficiently.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.1
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• pp.15-21
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• 2015

This paper presents the feasibility study on $CO_2$ carrier for carbon dioxide marine geological storage. Conceptual design was carried out to acquire $CO_2$ carriers by retrofitting existing vessels and new ship-building. Based on conceptual design, the acquisition cost of $CO_2$ carriers was estimated. Finally, necessary expense and number of ships were estimated based on operational plans for the assumed scenario.

• Journal of the Korea Safety Management & Science
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• v.10 no.3
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• pp.117-126
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• 2008

RFID system the key technology of ubiquitous era, has been emphasized in logistics. Logistic enterprises are required to apply RFID systems considering their investment costs, actual effectiveness, operational satisfaction and so on. For such a purpose, many applicable methods of RFID system have been developed A method that RFID tags are directly attached to products or pallets is utilized in most cases. However, this method requires expensive investment cost, frequent replacement of damaged tags for the small and medium (SM) third party logistics. In this paper, we analyze statistically the current status and requirements of SM third party logistics. Based on their requirements, we propose the realtime warehousing-delivery management by the method to attach a RFID tag to each warehouse rack, together with the economy analysis index in order to evaluate economical efficiency. Consequently, this method is expected to reduce Investment cost and to improve operational effectiveness and satisfaction.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.639-640
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• 2015

Traditional construction planning based on historical data and heuristic adjustment can no longer incorporate all the operational details and guarantee the expected performance. The variation between the expected and the actual production leads to cost overruns or delay. Although predicting reliable productivity on construction site is getting more important, the difficulty of this increases. In this regard, this paper suggested to develop BIM-integrated simulation framework. This framework could predict productivity dynamics by considering factors affecting on construction productivity at operational phase. We developed the following processes; 1) enabling a BIM model to produce input data for simulation; 2) developing the construction operation simulation; 3) running simulation using BIM data and obtaining productivity results. The BIM-integrated simulation framework was tested with structural steel erection model because steel erection work is one of the most critical process influencing on the whole construction budget and duration. We could improve to predict more dynamic productivity from this framework, and this reliable productivity helps construction managers to optimize resource allocation, increase schedule reliability, save storage cost, and reduce material loss.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.114-115
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• 2018

This paper studies a mechanism for cost-effective analysis of big data in the cloud environment. Recently, as a storage of electronic medical records can be managed outside the hospital, there is a growing demand for cloud-based big data analysis in small-and-medium hospitals. This paper firstly analyze the Amazon Elastic MapReduce which is a popular cloud framework for big data analysis, and proposes a cost model for analyzing big data using Amazon EMR with less cost. Using the proposed model, the user can construct a cost-effective computing cluster, which maximize the effectiveness of the analysis per operational cost.