• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.3
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• pp.338-342
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• 2014

Energy storage is a key issue when integrating large amounts of intermittent and non-dispatchable renewable energy sources into electric power systems. To maintain the instantaneous power balance and to compensate for the influence of power fluctuations from renewable sources, flexible capability for power control is needed. Adjustable Speed Pumped Storage Power Generator is pumped storage unit that is adjustable for pump output adjustments as well as the highest efficiency operations because it has fast response time. In this paper we address the adjustable speed pumped storage power generator for frequency control against the intermittence of wind turbine output and calculate the appropriate capacity of adjustable speed pumped storage power generator.

• Proceedings of the Korea Port Economic Association Conference
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• 2007.10a
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• pp.161-173
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• 2007

This paper considers the problem of determining the cargo flow and the transportation mode in each trade route while satisfying the demand. Especially, the problem incorporates short sea shipping in Korea, which is becoming more important in order to improve efficiency of Logistics. The objective is to minimize the sum of shipping and inland transportation costs. To solve optimally the problem, this paper employs a linear programming model, which is an operations research technique for optimization. The problem is formulated by extending the well-known network design problem by considering capacity at seaport and limitation of total number of vehicles. The model is solved using CPLEX, a commercial linear program software. The test results using a real cargo flow data in Korea show that the model represents closely the real situation.

• Communications for Statistical Applications and Methods
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• v.10 no.3
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• pp.1069-1086
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• 2003

This article presents the asymptotic theory of triple sampling procedure as pertain to estimating the shape parameter of Pareto distribution. Both point and confidence interval estimation are considered within the same inference unified framework. We show that this group sampling technique possesses the efficiency of Anscome (1953), Chow and Robbins (1965) purely sequential procedure as well as reduce the number of sampling operations by utilizing Stein (1945) two stages procedure. The analysis reveals that the technique performs excellent as far as the accuracy is concerned. The present problem differs from those considered by many authors, in multistage sampling, in that the final stage sample size and the parameter's estimate become highly correlated and therefore we adopted different approach.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.1
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• pp.91-96
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• 2002

Recently industry has moved towards automated operations with the goal of achieving better product quality greater productivity and reliability The pump design in characterized by extensive utilization of the related database which contains performance data. The inputs to the system are through interactive dialogue sessions and the basic input consist of flow rate, head, of fluid efficiency and the customer special requirements. These basic inputs along with the numerous rules in the knowledge bases and the mathematical modeling enable the effective design of the pump industry This paper represents the development of an automatic pump design system that was composed of a main program the data input module the drawing module the drawing edit module and was programed by the AutoLISP language under the Auto CAD program The developed system ultimately generates the design for a pump through the AutoCAD language.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.8
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• pp.1062-1068
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• 2000

The effect of heat exchanger surface treatment on the frosting/defrosting behavior in a fin-tube heat exchanger is investigated experimentally. It is found that the hydrophilic surface mainly influences on the frosting behavior, however, the hydrophobic surface gives some influence on the defrosting behavior. In view of frosting performance, surface-treated heat exchanger with either hydrophilic or hydrophobic characteristic shows a little improvement in the thermal performance than the aluminium heat exchanger with no surface treatment. The result reveals that the heat exchanger with hydrophobic surface treatment is more effective in view of the defrosting efficiency and time. The amounts of residual water on the surface-treated heat exchangers are shown to be smaller than those of the bare heat exchanger, therefore further improvements on the performance of re-operations are expected.

• Ocean and Polar Research
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• v.31 no.4
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• pp.361-368
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• 2009

An operational oceanographic system needs to be established for the preservation and management of marine environments and resources, and also to secure the safety and efficiency of marine operations in Korea. One of the major roles of operational oceanography is to deliver ocean science products which can meet the requirements of users such as marine industries, the general public, government agencies, and scientific research communities. Technical issues in relation to development of an effective operational oceanographic system in Korea are identified and discussed. Among others, cooperation among the agencies in ocean, meteorology, hydrology and environment, and also among those of neighboring countries is important for the development of an effective operational oceanographic system. The strategy for building a system that meets the demands of users, with consideration to potential problems, are explored.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.237-238
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• 2016

Rework is a major cause that adversely affects the performance of a construction project, such as schedule delay or cost overrun. In order to prevent rework, research has been mainly conducted to analyze the cause of rework, but limited to quantitatively measure cost of rework and analyze its impact on project performance. Therefore, this paper aims to analyze impact of rework cost using 369 rework items collected from 3 construction site. This research is expected to accurately determine control target of rework and to improve efficiency of business operations in construction project.

• Journal of Computational Design and Engineering
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• v.2 no.2
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• pp.119-127
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• 2015

In the case of a high-valuable asset, the Operation and Maintenance (O&M) phase requires heavy charges and more efforts than the installation (construction) phase, because it has long usage life and any accident of an asset during this period causes catastrophic damage to an industry. Recently, with the advent of emerging Information Communication Technologies (ICTs), we can get the visibility of asset status information during its usage period. It gives us new challenging issues for improving the efficiency of asset operations. One issue is to implement the Condition-Based Maintenance (CBM) approach that makes a diagnosis of the asset status based on wire or wireless monitored data, predicts the assets abnormality, and executes suitable maintenance actions such as repair and replacement before serious problems happen. In this study, we have addressed several aspects of CBM approach: definition, related international standards, procedure, and techniques with the introduction of some relevant case studies that we have carried out.

• Journal of IKEEE
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• v.19 no.4
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• pp.526-534
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• 2015

In this paper, we studied the use of the foreground and background features and SVM classifier to improve the accuracy of offline handwritten numeral recognition. The foreground features are two directional features: directional gradient feature by Kirsch operators and directional stroke feature by local shrinking and expanding operations, and the background feature is concavity feature which is extracted from the convex hull of the numeral, where the concavity feature functions as complement to the directional features. During classification of the numeral, these three features are combined to obtain good discrimination power. The efficiency of our scheme is tested by recognition experiments on the handwritten numeral database CENPARMI, where SVM classifier with RBF kernel is used. The experimental results show the usefulness of our scheme and recognition rate of 99.10% is achieved.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.223-226
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• 2004

Many extensive researches in the area of sensor's technology for corrosion monitoring in concrete structures have increasingly been carried out in recent years. This paper gives a brief discussion on the principles and usage of the role of sensors involved in both corrosion initiation and propagation steps of reinforcement corrosion monitoring in concrete structures. Special attention was given to the review of various sensing devices, selection of reliable sensing devices for detecting reinforcement corrosion at the particular environment and at the efficiency of the devices used. Various sensing operations in new and existing concrete structures are also described.