• Title/Summary/Keyword: low-precision

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Dvnarnic Reswnse of Laminated Com~osite Shell under Low-Velocity Impact (복합적층쉘의 저속충격에 대한 동적 거동 해석)

  • 조종두;조영훈
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1994.10a
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    • pp.969-974
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    • 1994
  • The dynamic behavior of graphite/epoxy laminated composite shell structure due to low-velocity impact is investigated using the finite element method. In this analysis, the Newmark's constant-acceleration time integration algorithm is used. The impact response such as contact force, central deflection and dynamic strain history form shell structure analysis are compared with those form the plate non-linear analysis. The effects of curvature, impact velocity and mass of impactor on the composite shell are discussed.

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Friction Properties of Carbon Coated Ultra-thin Film using Taguchi Experimental Design (다구찌 실험계획법을 이용한 탄소코팅 초박막의 마찰특성)

  • 안준양;김대은;최진용;신경호
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.4
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    • pp.143-150
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    • 2003
  • Frictional properties of ultra-thin carbon coatings on silicon wafer were investigated based on Taguchi experimental design method. Sensitivity analysis was performed with normal load, relative humidity, deposition process, and coating thickness as the variables. It was found that despite low thickness, the carbon coating resulted in relatively low friction coefficient. Also, the frictional behavior was affected significantly by humidity and normal load.

Computer Simulation and Control performance evaluation of Ultra Precision Positioning Apparatus using DC Servo Motor (DC Servo Motor를 이용한 초정밀 위치결정기구의 컴퓨터 시뮬레이션 및 제어성능 평가)

  • 박기형;김재열;윤성운;이규태;곽이구;송인석;한재호
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.9 no.6
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    • pp.164-169
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    • 2000
  • Recently, High accuracy and precision are required in various industrial field especially, semiconductor manufacturing apparatus, Ultra precision positioning apparatus, Information field and so on. Positioning technology is a very important one among them. As such technology has been rapidly developed, this field needs the positioning accuracy as high as submicron. It is expected that the accuracy of 10nm and 1nm is required in precision work and ultra precision work field, respectively by the beginning of 2000s. High speed and low vibration are also needed. This work deals with the design method and control system of Ultra precision positioning apparatus. Control performance and stability analysis were performed in advance by modeling and designing the controller with Simulink.

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Temperature Characteristics of Cascade Refrigeration System by Pressure Adjustment

  • Chung Han-Shik;Jeong Hyo-Min;Kim Yeong-Geun;Rahadiyan Lubi
    • Journal of Mechanical Science and Technology
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    • v.19 no.12
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    • pp.2303-2311
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    • 2005
  • Super low temperature has many applications nowadays, from the chemical processing, automotives manufacturing, plastic recycling, etc. Considering of its wide application in the present and the future, study of the super-low temperature refrigeration system should be actively carried out. Super low state temperature can be achieved by using multi-stage refrigeration system. This paper present the development and testing of cascade refrigerator system for achieving super-low temperature. On this experiment, two different types of HCFCs refrigerants are utilized, R-22 and R-23 were applied for the high stage and the low-pressure stage respectively. The lowest temperature in the low-pressure evaporator that can be achieved by this cascade refrigeration system is down to $-85^{\circ}C$. This experiment is aimed to study the effect of inlet pressure of the low-pressure stage evaporator and low-pressure stage compressors inlet pressure characteristics to the overall temperature characteristics of cascade refrigeration system.