• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.865-869
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• 1997

In recent years, there has been increasing demand of ultra-fine grain graded cemented tungsten carbide material with high hardness and toughness which is used as high speed cutting tool for development in semiconductor, electronics and die/mold industry, which bring into limelight high-precision, high-efficient machining of sculptured surfaces. This paper deals with the performance of variation in the ultra-fine grain graded cemented tungsten carbide material such as grain size, hardness and density varied according to the volume of added elements, Co or TaC, and he changing of mixing, sintering process. Also, the performance of developing material with uniformed grain size of 0.5${\mu}{\textrm}{m}$ is compared with other domestics' & foreign companies' with analyzing and cutting performance testing.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.803-808
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• 2017

Minimum Energy Performance Standard(MEPS) has been adapted in Korea since 2008. The efficiency standard of variable speed motors is scheduled for publication shortly. In this paper, author reviews the technical trends associated with a high efficient electric motors by reference to research papers, and reviews the research direction to prepare for IE5. This paper provides an overview of high efficiency motors. Various applications have been covered.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.4A
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• pp.519-527
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• 2000

This paper suggests and analyzes the Serially Concatenated Space-Time Code(SCSTC) with the possibility of a efficient high-speed transmission in a band limited channel. The suggested code has a structure that uses the interleaver to connect the space-time code as an inner code and the convolutional code as a outer code serially. This code keeps the advantage of high-speed transmission and also has the high BER performance. The performance of the suggested system is compared with the conventional bandwidth efficient trellis coded modulation, such as a Serially Concatenated Trellis Coded Modulation (SCTCM) and a Turbo-Trellis Coded Modulation(Turbo-TCM). The results show that the suggested system has a 2.8dB and 3dB better BER performance than SCTCM and Turbo-TCM respectively in case of the transmission rate 2b/s/Hz in fading channel.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.133-138
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• 2010

This paper describes on aerodynamic characteristics of pantograph system for Next generation high speed train(HEMU-400). The pantograph which supports electric power is located on the roof. Because of this, it generate high drag, severe acoustic noise and vibration which induced unstable flow due to complex configuration. Therefore, the design of high efficient pantograph needs to increase operational speed. In this research, wind tunnel tests were performed to design a high efficient pantograph system using 1/4 scaled model which were KTX-II pantograph, single arm pantograph and periscope type pantograph with square cylinder shape panhead and optimized shape panhead. For real operational condition, flow directions were adapted by rotation of pantograph. From this results of wind tunnel, it is checked that the pantograph with optimized panhead and single arm type or periscope type has better aerodynamic performance. In addition, lift control device and spoiler in pantograph were tested to investigate the validity of application.

• Journal of Power System Engineering
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• v.14 no.6
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• pp.75-82
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• 2010

In this study, the topics for free-surface wave simulation, nonlinear hydrodynamic force, and the critical resonance frequency of so-called ${\tau}=U{\omega}/g$=1/4 are discussed. A high-order spectral/boundary element method is newly adapted as an efficient numerical tool. This method is one of the most efficient numerical methods by which the nonlinear gravity waves can be simulated and hydrodynamic forces also can be calculated in time domain. In this method, the velocity potential is expressed as the sum of surface potential and body potential. Then, surface potential is solved by using the high-order spectral method and body potential is solved by using the high-order boundary element method. By the combination of these two methods, the wave-making problems by a submerged sphere oscillating with forward speed under the free-surface are solved in time domain.

• Proceedings of the Society of Korea Industrial and System Engineering Conference
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• 2002.05a
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• pp.51-56
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• 2002

A Korea next-generation high-speed rail system represents a typical example of large- scale multi-disciplinary systems, consisting of subsystems such as train, electrical hardware, electronics, control, Information, communication, civil technology etc. The system design and acquisition data of the large-scale system must be the subject under strict configuration control and management. The system therefore, must be developed using systems engineering that is a efficient and effective methodology to design such a complex system and manage its development. This paper presents the results from a computer-aided systems engineering application to the Korea next generation high-speed railway project. Especially, the focus of the study was on requirement management and PBS management.

• 한국전산유체공학회:학술대회논문집
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• 2000.05a
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• pp.51-59
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• 2000

The Interactions of shock wave with turbulent boundary layers in high-speed flows cause complex flowfields which result in increased adverse pressure gradients, skin friction and temperature. Accurate and reliable prediction of such phenomena is needed in designing high-speed propulsion systems. Such analyses of the complex flowfields require sophisticated numerical scheme that can resolve interactions between shock wave and boundary layers accurately. Therefore the purpose of the present. article is to introduce an accurate and efficient mixed explicit-implicit generalized Galerkin finite element method. To demonstrate the validity of the theory and numerical procedure, several benchmark cases are investigated.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.951-956
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• 2007

This paper suggests a high-speed control method which is suitable for multi-joint robots using a real-time stand-alone controller for general-purpose. The fast processing controller consists of a PCI Interface Board and 2-axe PWM drivers. The PCI Interface Board consists of 32-channel PWM output ports, 32-channel Encoder Counters, 32-channel A/D Converters and 48-channel Digital I/O ports, and all the I/O data transmissions are completed within 1ms. And The 2-axe PWM driver can be redesigned easily in order to embed in each link. Experimental implementations show that the high-speed control method can be used for the real-time control which is essential to controlling of multi-body robots such as humanoid robots. Especially, it is efficient for realizing the model-based motion control in demand of much calculation time by the high I/O communication speed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.293-295
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• 2000

In this paper, we are present efficient informationalized education strategy that is used B-ISDN based on high speed network for multi-user and all process associated with it. We are proposed to be strengthen information application as providing multimedia service, international competition over construction of high speed information network, and international competition over being bring up specialist which takes the lead informationalized education policy with the based on high speed information network.

• Proceedings of the KSR Conference
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• 2001.10a
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• pp.104-110
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• 2001

During the last several years, the high speed railway system has been constructed and it is scheduled to open sometime in 2004. To fulfil its duties, it is essential to view intermodalism in the context of broader technological developments in easy access to high speed railway station. And also, to understand the economic importance of intermodal transportation, continual research is needed on the costs and distributional effects of alternative intermodal mechanisms for public works, including direct service to local station or easy transfer to other mass transportation modes. In this paper, necessary courses for local governments involvement are taken, and additional resources must be found that will benefit the entire railway system.