• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.425-430
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• 2008

To verify the system performance of portable AE leak diagnosis system which can measure with moving conditions, AE activities such as RMS voltage level, AE signal trend, leak rate degree according to AE database, FFT spectrum were measured during operation on total 11 valves of the secondary system in nuclear power plant. AE activities were recorded and analyzed from various operating conditions including different temperature, type of valve, pressure difference, valve size and fluid. The results of this field study are utilized to select the type of sensors, the frequency band for filtering and thereby to improve the signal-to-noise ratio for diagnosis for diagnosis or monitoring of valves in operation. As the final result of application study above, portable type leak diagnosis system by AE was developed. The outcome of the study can be definitely applied as a means of the diagnosis or monitoring system for energy saving and prevention of accident for power plant valve. The purpose of this study is to verify availability of the acoustic emission in-situ monitoring method to the internal leak and operating conditions of the major valves at nuclear power plants. In this study, acoustic emission tests are performed when the pressurized temperature water and steam flowed through glove valve(main steam dump valve) and check valve(main steam outlet pump check valve) on the normal size of 12 and 18 ". The valve internal leak monitoring system for practical field was designed. The acoustic emission method was applied to the valves at the site, and the background noise was measured for the abnormal plant condition. To improve the reliability, a judgment of leak on the system was used various factors which are AE parameters, trend analysis, frequency analysis, voltage analysis and amplitude analysis of acoustic signal emitted from the valve operating condition internal leak.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.3
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• pp.50-64
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• 2011

In this paper, a DC-coupled photovoltaic (PV), fuel cell (FC) and ultracapacitor hybrid power system is studied for building microgrid. In this proposed system, the PV system provides electric energy to the electrolyzer to produce hydrogen for future use and transfer to the load side, if possible. Whenever the PV system cannot completely meet load demands, the FC system provides power to meet the remaining load. The main weak point of the FC system is slow dynamics, because the power slope is limited to prevent fuel starvation problems, improve performance and increase lifetime. A power management and control algorithm is proposed for the hybrid power system by taking into account the characteristics of each power source. The main works of this paper are hybridization of alternate energy sources with FC systems using long and short storage strategies to build an autonomous system with pragmatic design, and a dynamic model proposed for a PV/FC/UC bank hybrid power generation system. A simulation model for the hybrid power system has been developed using Matlab/Simulink, SimPowerSystems and Matlab/Stateflow. The system performance under the different scenarios has been verified by carrying out simulation studies using a practical load demand profile, hybrid power management and control, and real weather data.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.04a
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• pp.70-77
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• 1996

Recently many efforts have been made to improve the efficiency of design and production of the structures using the automation system. But, this work has been progressed as independent or partial system. And, the study on the integrated system is not sufficient in application for practical problems yet. This paper deals with the fundamental concept of modeling system and application method on structural modeling. At first, the core of the integrated system is a shape modeling system that can represent the geometric and topological information. This system must be designed as an open system to be combined with each independent automation system. The appropriate concept to realize this system on structural modeling is object oriented modeling and this enables to integrate each automation system successfully, This concept was applied to automatic mesh generation. For shape modeling system, half-edge data structure that is being used in solid modeling was modified to handle the plate structure in the plane. And, to generate the triangular meshes, direct node connection method was used. And, as a result, the integrated system that generate the meshes of two dimensional structure automatically was realized. And, programmed by C++, these systems can be combined with other systems easily and have good reusability.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.3
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• pp.343-350
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• 2009

Recently ship safety regulations are being reinforced to improve maritime safety and to prevent maritime pollution by International Maritime Organization. It means that the regulation is becoming more proactive rather than reactive. In the mean time, design philosophy is also moving from rule based design to performance and simulation based design. In this paper, a study on practical application of the damage safety assessment system is carried out. The damage stability and the survivability of a cargo ship that was designed based on current regulation is investigated using performance based design tools in order to improve the safety of the design and verify the performance of the developed damage safety assessment system. To do this, damage scenarios is established and the characteristics and geometry the cargo ship is modeled. A new design alternative is proposed with small change in the internal arrangement based on safety evaluation results of the current design.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.11
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• pp.625-631
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• 2003

The purpose of this paper is to assess experimentally system stability of the 154 ㎸ transmission system due to the current of the forthcoming AC High-Speed Railway (HSR) era. It introduces a simple method to evaluate the system stability The proposed method also shows the relationship between stability and power losses, and the stability indices made by the numerical process proposed in this paper will be used to assess whether a system can be stabilized or not. This paper also presents the improvement of the stability via loss reduction using STATCOM. Reactive power compensation is often the most effective way to improve both power transfer capability and system stability. The suitable modeling of the electric railway system should be applicable to the PSS/E. In the case study the proposed method is tested on a practical system of the Korea Electric Power Corporation (KEPCO) which will be expected to accommodate the heavy HSR load. Furthermore, it prove that the compensation of voltage drop and its by-product, loss reduction is closely related to improvement of system stability.

• Journal of The Korean Association For Science Education
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• v.16 no.2
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• pp.146-153
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• 1996

The study reported here is a part of the Korean Science Education Database (SEDB) project, a long-term effort to improve science education by providing educational information to science educators. The purpose of the SEDB project is to improve access to science resources available to teachers, students, parents, and others. Three educational database have been investigated and discussed in depth. The Educational Resources Information Center (ERIC) that is the largest education database in the world and the Eisenhower National Clearinghouse for Mathematics and Science Education (ENC) that is creating an easy-to-use catalog of mathematics and science curriculum materials have been investigated on the aspect of system and operation. The pilot form of the SEDB developed in this study has committed itself to reaching audiences that include practitioners and policymakers. The SEDB should be a collection of the most up-to-date and comprehensive listing of science curriculum materials in the nation, because educators need better access to the best instructional materials and programs to continually improve science education our nation's science. The researchers recommend the practical tips for developing an effective science education database.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.44
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• pp.213-238
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• 2009

This thesis examines the problems faced in the clearance procedures of Korea's e-customs system for which improvements are necessary, and suggests various ways of overcoming those problems. Practical implications regarding the advancement of Korea's e-customs system are as follows. First, the substructure of the e-customs clearance system, which is the basis for the establishment of a global single window, should be developed into a more modern and advanced system. Second, additional improvements in the law are required to render the broad array of Internet-based export and import documents legally binding. Third, customized services should be provided in order to improve the operating efficiency of the e-customs clearance system. Fourth, the reputation of Korea's e-customs clearance system should be raised via the strengthening of a cooperative system between concerned parties, including exporters and importers. This innovative approach to systematic improvements will come about when we can simplify current customs clearance procedures and establish a fairer customs inspection administration regime. Additionally, when we review the methods intrinsic to our customs system, we must emphasize the urgency of proper completion of related systems and arrangements in the trade business and similar fields.

• Journal of Korean Society for Quality Management
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• v.45 no.3
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• pp.379-391
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• 2017

Purpose: The study proposes extended application of reviewing and developing international quality assurance system for useful and practical quality stabilization of foreign military product. There are several problems with quality assurance activities for foreign military products. To improve theses problems, this study researches measures and effects of entrustment of quality assurance activities to suppliers group abroad by utilizing the system. Methods: In order to carry out the research, consignment system for international quality assurance activity of advanced country has been analysed through this study. By applying the consignment system to the case of foreign military product, the possibility and effects of consignment is researched. Results: Through this study the procedure and substance of the international quality assurance system is verified. The quality assurance activities were consigned to suppliers group by utilizing the system, thus application basis for international quality assurace activities is established. Conclusion: Defense Import through The Quality Assurance System of trade countries using the International Quality Assurance System suggests the solution to endemic problems. The Introduction Military Product with the Quality Assurance System of Korean Government improves the competitiveness of defense export.

• Journal of Convergence for Information Technology
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• v.10 no.8
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• pp.239-249
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• 2020

In this study, 205 graduates of beauty majors were surveyed for the purpose of the study to analyze the differences between factors in each major by examining the impact of the perception of beauty education courses on site utilization, job utilization, and job satisfaction. The study found that practical skills were required as a supplemental major subject, and the theory

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.4
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• pp.12-18
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• 1995

To improve the performance of diesel automobile engine, we designed new fuel supply system named ultrasonic fuel supply system. The performance test of diesel automobile engine carried out to examine possibility of practical use of ultrasonic fuel supply system to test engine. This paper deals with the comparative results of performance test of diesel automobile engine in terms of smoke, HC, SFC, PS, thermal, efficiency, torque. Following are obtained result. 1) In naturally aspirated diesel engine, when we use ultrasonic fuel supply system output, fuel consumptions are improved and exhaust gas reduced significantly. 2) In turbo-charging diesel engine both using of ultrasonic fuel supply system and using of conventional injector, engine performance and exhaust gas temperature are almost constant. 3) In turbo-charging diesel engine, when we use ultrasonic fuel supply system, NOx are emitted approximately 3.5% higher than total average. 4) In turbo-charging diesel engine, when we use ultrasonic fuel supply system, smoke and CO are 17% and 11.8% improved respectively.