• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.9 no.4
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• pp.78-85
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• 1995

This paper covers stability and stabilization of Multi-Excited Induction Motor used in numberous electric equipment system of industrial field. The induction motor with multi-excitation has tow sets of three-phase system : One is connected to the AC source to supply most power required at the load, and the other is to the inverter for variable frequency and/or magnitude of voltage. The conventional induction motor is operated under single excitation mode only, that is called induction mode. But in multi-excited induction motor both the induction mode and the synchronous mode are possible, and the proposed multi-excited induction motor can be driven as a synchronous motor by the extra three-phase input. At the synchronous mode the efficiency is improved so higher than that at induction mode or conventional induction motor. The rating of the inverter used for speed control of numberous electric equipment system can be reduced upto one-tenth of that for conventional induction motor. Also the cost and maintenance fee of multi-excited induction motor can be reduced compared to any other motor.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1995.04a
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• pp.73-81
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• 1995

In Korea, the pilot construction of the first high-speed railroad on the Seoul-Pusan has already started 2 years ago. In the thesis, an attempt is made to develop reliability-based integrity-assessment models for the computer-aided control and maintenance of high-speed railroad bridges. The strength limit state models for PC railroad bridges encompass the bending and shear strengths as well as the strength interaction equations which simultaneously take into the element and system reliablities of the proposed limit states and reliability models. Then, the actual load carrying capacity and the realistic safety of bridges are evaluated using the system reliability-based equivalent strength, and the results are compared with those of the element reliability-based or conventional methods. Various parametric studies are performed for the proposed reliability-based safety and integrity-assessment models using the actual PC box girder bridges used in the pilot construction. And the sensitivity analyses are performed for the basic random variables included in strength limit state models. It is concluded that proposed models may be practically applied for the rational assessment of safety and integrity of high speed railroad bridges.

• Journal of KIBIM
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• v.3 no.3
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• pp.1-8
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• 2013

In general, a two-dimensional platform were used to manage the structural inspection information. But we performed a study on utilizing 3D model to input and display the information of structure inspection. Coarse and Fine model of structure were used to input the information. 3D model combined with database built from record plan and field inspections data and rating will provide more intuitive and effective environment for inspectors in bridge maintenance.

• Journal of Korea Society of Digital Industry and Information Management
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• v.13 no.1
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• pp.197-211
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• 2017

In recent years, it is natural that the development and the maintenance of information systems are strongly dependent on outside service providers for economic reasons, especially in public sector. There has been an unexpected growth in the number of selection activities for outsourcing related works. At this time, selection of the contractor generally considers the proposals received based on the RFP(requested for proposal) and determines the ranking by experts committee. However, it is difficult even for expert giving a specific numeric score in weighting criteria or rating alternatives. In this context, an extended fuzzy TOPSIS method is applied for selection problem of IT proposals. A numerical illustration is also provided to demonstrate the applicability of the approach. This approach is very practical to help decision makers in assessing proposals during the selection phase under uncertainties.

• Journal of Construction Engineering and Project Management
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• v.1 no.2
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• pp.1-10
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• 2011

Bridges are critical and valuable components in any road and rail transportation network. Therefore bridge remediation has always been a top priority for asset managers and engineers, but identifying the nature of true defect deterioration and associated remediation treatments remains a complex task. Nowadays Decision Support Systems (DSS) are widely used to assist decision makers across an extensive spectrum of unstructured decision environments. The main objective of this research is to develop a requirements-driven methodology for bridge monitoring and maintenance which has the ability to assess the bridge condition and find the best remediation treatments using Simple Multi Attribute Rating Technique (SMART); with the aim of maintaining a bridge within acceptable limits of safety, serviceability and sustainability.

• New & Renewable Energy
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• v.6 no.4
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• pp.41-49
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• 2010

Over the last decade, wind turbine industry has rapidly increased around world. These days many parts of the wind generators are induction generator. But it has some problems such as gearbox failure, rotor excitation and maintenance. Thus many manufacturers are considered permanent magnet synchronous generator named PMSG and direct drive. PMSG uses NdFeB magnet has many the advantage compare with induction generator. In this study, 3MW class outer rotor type PMSG for wind turbine is proposed. The generator features 2.6m stator outer radius, 1200mm stator length, 81 pole pairs, 14 rated rpm, 42kN/$m^2$ shear force density and 94.2% efficiency. Design and analysis generator using FEM program. Then calculate and derivate no load voltage, losses, conductor temperature. To reduce total harmonic distortion and cogging torque, the stator is applied the stator skewing. And to evaluate the designed generator, compare with other generators by active mass per rating torque and torque density.

• Proceedings of the KSR Conference
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• 2001.05a
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• pp.431-436
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• 2001

Rockfall has long been a serious problem, especially derailment of train running on the track in mountainous regions. The purpose of this study is to suggest the reasonable items of check and evaluation to railroad rock slopes for safe maintenance and management of rockfall-worried railroad sites. Therefore, main and sub items were extracted from the survey of foreign and other authorities' cases and evaluation table (temporary) composed of items classified by important degree was suggested. To evaluate the availability and reasonability of items, statistical analysis based on field investigation namely SMR(Slope Mass Rating) and explanation values was carried.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1095-1097
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• 1993

The double excited induction motor has two sets of three-phase system : One is connected to the ac source to take care of energy convertion, and the other is to the inverter controlable frequency and/or magnitude of voltage, both of the induction mode and the synchronous mode are possible in double excitation motor, and the proposed double excitation motor can be driven as a synchronous motor by the extra three-phase input. At the synchronous mode the efficiency is improved so higher than that at induction mode or induction motor. The rating of the inverter used for speed control can be reduced upto one-fifth of that for conventional induction motor. Also the cost and maintenance fee of double excitation induction motor can be reduced compared to any other motors.

• Journal of Intelligence and Information Systems
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• v.10 no.2
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• pp.111-131
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• 2004

Software change is an essential operation for software evolution. To maintain the system competently, managers as well as developers must be able to understand the structure of the system but the structure of software is hidden to the developers and managers who need to change it. In this paper, we present a system (OntCIA) for supporting change impact analysis for rating and billing domain based on the semantic web technology. The basic idea of OntCIA is to build a domain knowledge base using an OWL ontology and RDF to implement change impact analysis system that would support the managers and software developers in finding out information about structure of large software system. OntCIA allows users to incrementally build an ontology in rating and billing domain and provides useful information in response to user queries concerning the code, such as, for example 'Find the modules which have a role for confirming new subscription'. The strengths of OntCIA are its architecture for easy maintenance as well as semantic indexing by automatic reasoning.

• Journal of Digital Convergence
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• v.13 no.1
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• pp.439-447
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• 2015

The game industry has a very important position. However, a problem with the game rating and legal issues so called "Internet Game Shutdown System" is with significant impact. So, this study looking for many information on this issue, over the course of the study of solutions was looking for a way to contribute to the game industry. The status of the domestic game industry and the institutional and legal problems were studied. In this study, for the development of the game industry, the government's policy support is needed. And game related-government agencies should be the maintenance of law and institutions and reasonable arrangements for the work of government agencies.