• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.440-445
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• 2002

The characteristic equation for regenerative chatter loop including a delay element replaced by a rational function is presented by a linear differential-difference equation, accounting for the dynamics of the AMB controllers, the uncut chip thickness equation and the cutting process as well as the rigid spindle dynamics itself. The chatter stability analysis of a rigid milling spindle suspended by 5-axes active magnetic bearings(AMBs) is also performed to investigate the influences of the damping and stiffness coefficients of AMBs on the chatter free cutting conditions, as they are allowed to vary within the stable region formed by the AMB control gains. Several cutting tests varying the derivative gains of the AMB were performed to investigate the regenerative chatter vibrations, and it was concluded that the theoretical analysis results are in good consistency with the test results.

• Tribology and Lubricants
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• v.13 no.3
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• pp.56-62
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• 1997

Sealing an oil-air mixture plays important roles to have an enhanced lubrication for high speed spindle. High speed spindles require non-contact type sealing mechanism. In this study, an optimum seal design to minimize leakage is concerned in the aspect of flow control. This paper categorizes geometries of mostly used non-contact type seals and analyzes each leakage characteristics to minimize a leakage on sealing area. Effect of minimum clearance and its position are considered according to variation of detail geometry. The estimation of non-leaking property is determined by amount of pressure drop in the leakage path assuming constant leakage flow. To simulate an oil jet or oil mist type high speed spindle lubrication, the working fluid is regarded as two phases that are mixed flow of oil phase and air phase. Both of the turbulence and the compressible flow model were introduced in CFD(Computational Fluid Dynamics) analysis. Design parameters has been induced to minimize leakage in limited space, and a methodological study on geometrical optimization has been conducted.

• Journal of the KSME
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• v.34 no.2
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• pp.118-125
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• 1994

미래기술은 컴퓨터와 통신이 주도하는 정보화 기술을 주축으로 점점 고성능화, 지능화 기계의 등장을 요구하며, 기계공학도 최근 그 개념 자체가 급속히 변화하고 있다. 교육계와 산업계에서는 구태의연한 교과과정에서 탈피하여 전자공학과 전산공학을 응용하는 교육과 동시에 더욱 심도 있는 기본교육을 요구하고 있다. 특히 유체공학은 현상론적 이해가 필요한 실험과학의 범주이 므로 실험실 교육이 절실한 학문이다. 미래지향적인 유체공학 실험교육의 개선방향은 개인용 컴퓨터를 적극활용하여 참여하는 실험을 필수적으로 운용하도록 유도하고 학생으로 하여금 물 리적 이해와 함께 창의적인 정보창출과 정보처리기법의 경험을 얻도록 해야한다. 아울러 다각 적이고 효율적인 실험장치를 설계하여 유체역학의 기본이론들이 충분히 이해될 수 있는 데몬스 트레이션용 실험이나 Kit형 실험도 더욱 보완될 필요가 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.281-284
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• 2003

Development of internet had centered on that offer universality of expression. But, graphic processing of expression center has many inconveniences because of method that is not structural in World Wide Web. Announced SVG that is XML application to permit efficient expression and storage of vector graphic expression, share in W3C to supplement these things. Therefore, because using SVG document in this treatise, edit vector graphic through interface that could edit expressed graphic object directly structural edit and screen that is offered in graphic edit system form and designed SVG edit system to express. This system may use usefully to efficient XML graphics processing on the GIS system and Mobile service environment and so on.

• 한국정보통신설비학회:학술대회논문집
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• 2002.08a
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• pp.85-104
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• 2002

최근 정부(정보통신부)는 사이버 아파트를 포함하여 초고속 정보통신망을 2005년까지 구축하여 각 가정당 10Mbps의 고속 정보통신서비스를 실현한다는 계획을 발표하고, 초고속 정보통신을 활성화하므로 정보통신 선진국 진입을 위하여 "초고속 정보통신 건물 인증제도"를 발표, 현재 시행하고 있다. (1999.7 제정발표) 그러나 시행 과정에서 아파트 중앙 관리실에 있는 MDF 이후의 광케이블과 기타 공사는 건설회사에서 시공하고 중앙 관리실 MDF 이전의 광케이블 공사와 중앙관리실 LAN시설 등의 공사는 통신 전문업체로 하여금, 입주자 별도 부담금으로 시공하고 있다. (컨소시엄구성) 최근 아파트 분양열기 고조로 건설회사 마다 "초고속 정보통신아파트"인증 1등급이라고 선전 및 분양광고 중인데 실제는 "1등급"이 아니고 "2등급" 또는 "3등급"인 경우가 있어, 정부가 목표하는 각 가정당 10Mbps, 개인당 2Mbps 고속정보통신 서비스는 실현성 문제점이 있다. 정부의 인증심사 기준에 중앙관리실 장비 등에 대한 것은 심사기준에 누락되어 있고 또 사생활 정보보호를 위한 대응기술, 시스템 준비 정도까지 포함하여 종합적으로 평가한 뒤 인증을 부여하여야 한다는 것이 본인의 연구 초점이다. 사이버 아파트란 광통신을 주축으로 영상과 음성, 데이터를 자유 자재로 전송 처리하는 초고속 정보통신망을 이용하는 것으로 LAN 장비를 이용하여 각 세대간 통신은 물론 누구나 인터넷을 사용할 수 있는 기능이 있는 설계된 아파트를 말한다. 사이버 아파트의 네트워크에는 금융, 홈쇼핑, 예약, 지역정보, 관공서, 의료서비스, 레저 생활정보 등 차별화된 콘텐츠 확보가 필요하다. 본 연구의 핵심은 사이버 아파트의 현 실태와 문제점, 정부의 인증심사 기준의 미비점과 문제점, 사이버 아파트의 기능, 구성요소, 시스템 구축, 서버활용도, 장비들에 관한 것과 그리고 정부의 사이버 아파트 육성정책, 정보보호 대책과 관련업체들의 동향 등을 연구하여 요약 정리하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.788-791
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• 2002

The present Web surroundings is composed of HTML(Hypertext Mark-up Language) and thereby users obtains web informations mainly in GUI(Graphical User Interface) environment by clicking mouse in order to keep up with hyperlinked informations. However it is very inconvenient to work in this environment comparing with easily accessed one in which human's voice is utilized for obtaining informations. Using VoiceXML, resulted from XML, for supplying the information through telephone on the basis of the contemporary matured technology of voice recognition/synthesis to work out the inconvenience problem, this paper presents the research results about VoiceXML Web Browser designed and implemented for realizing its technology.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12C
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• pp.249-254
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• 2001

A receiver ASIC for fiber optic modules of STM-1 optical communication has been fabricated with 0.65 $\mu\textrm{m}$ CMOS technology. The ASIC has a limit amplifier circuit for the 155.52 Mbps data reshaping, and a clock extraction circuit for the 155.52 MHz clock recovery. The ASIC has an acquisition aid and LOS monitoring circuit for properly operation with near 155.52 MHz clock frequency in case of the data loss due to transmission line open or data transfer fail. Measured results show that the circuit reshapes data from 5 mV to 1 V wide range of input voltage condition, add it recovers system clock with stable on any condition.

• Journal of Korea Game Society
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• v.21 no.6
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• pp.111-124
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• 2021

Starting with painting, it is the frame that plays the main role in movies, cartoons, and games as well as the act of attracting the audience's attention. Knowing about a frame is to be able to read and use the frame. Therefore, this paper deals with frames of digital games, especially multiple frames that complement the limited configuration of primary frames. In this paper, frame within frames are classified into structural frames, which are the basic components of the game, temporal frames, which reflect player behavior, and surface frames representing the characteristics of existing visual media. Through this, we examine the aspects of frame within a frame as digital game design equipment. This paper is meaningful in that it derives the possibility of using frame within a frame of games in the future and provides a mechanism for frame within a frame analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3357-3362
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• 2014

The purpose of this research was to develop a resonance electric power generator to harvest vibration energy while the vehicle is driving on a road surface. The electric power generator in the paper was designed using the resonance phenomenon to effectively respond to vibrations from the road surface, which is a comparatively small energy source. Vibration displacement analysis using MATLAB and transient analysis using Ansys MAXWELL, which is a commercial electromagnetic analysis program, was performed to predict the input velocity for the generator and verify the electric power generation. If this electric power generator is applicable to hybrid or electric vehicles, it can be valuable around an automotive electric system and help maintain the performance of the vehicle battery.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1497-1508
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• 1993

Real-time mobile robot controllers usually have been designed focused on control theory without paying attention to the importance of system integration. This paper demonstrates that autonomous mobile robots require a real-time controller with a wide range of capabilities in addition to control theory. An architectural frame work supporting these capabilities has been designed in actual hardware environments. Individual modules such as a path planner, a path tracking controller, position estimators, wheel controllers and other cruical elements have been successfully integrated into the control system using this frame work. The overall performance of the system was investigated via a series of tracking experiments with a prototype mobile robot named LCAR deveoped in the laboratory. The context of the research involves the architecture, its implementation and experimental results.