• 제목/요약/키워드: Linear scale

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레이저를 이용한 광학식 리니어 스케일의 분해능 향상에 관한 연구 (High resolution linear scale using collimated LASER)

  • 박윤창;정경민
    • 한국공작기계학회:학술대회논문집
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    • 한국공작기계학회 1999년도 춘계학술대회 논문집
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    • pp.170-174
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    • 1999
  • The main scale of linear scale greatly affects on the precision of displacement measurement. Especially when needing the long range measurement, the length of main scale should be increased accordingly. In this paper, we propose a linear scale that uses laser interference pattern as main scale for long range measurement. The linear scale is similar to Michelson interferometer excepting that the reference mirror is tilted so as to obtain interference fringe pattern and a grating panel is attached on a quadratic photo diodes. Four kinds of grating having phase differences of 0, $\pi$ /4, $\pi$ /2, 3 $\pi$ /4 are arranged on the panel. The experimental results show that signals of - quadratic photo diode, A, B,$\overline{A}$ and $\overline{B}$ are cosine wavelike and successive signals have phase difference of $\pi$/4 each other. So the proposed method can achieve improved measurement resolution.

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Ne-Ne 레이저의 간섭을 이용한 고정밀 리니어 스케일의 제작에 관한 연구

  • 전병욱;박두원;이명호;한응교
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 1991년도 춘계학술대회 논문집
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    • pp.176-194
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    • 1991
  • A study on the Manufactiring of High-Precision Linear Scale by the Use of He-Ne Laser Interference Of late, along with the advancement of procision machining technology, the reauirement of super-precision measurement increases as time goes on, and the precision and accuracy of standard scale which is a basis of procision measurement has been cognized as a oriterion of industrial development in a nation. Up to now, mechanical and chemical methods have been widely employed to carve scale lines on linear scale, and it is impossible for the linear scale manufactured by means of those methods to guarantee the measurement with sub-micron level owing to errors attended with various problems. And the measuring length also bears errors subjected to the influence of surroundings condition, and shows inefficient circumstances in measurement on the ground of the complexity of measuring procedure as well as massive measuring apparatus. Hence in this paper, we described on technology by which we can carve scale lines thru optical method under the condition of laboratory by using rhcoherence of He-Ne two-mode stabilized laser and in turn, put it to practical use as linear scale for the measurment of lengrh. In this researchin the case of setting scale interval to 20 .mu. m, we employed super-precision scale-carving device associated by Ar larser and acoustic optical modulator in lieu of flsahing lamp scale-carving device, and we consequently obtained superior linear scales carved with precision and accuracy of .+-. 0.3 .mu. m.

Multiscale method and pseudospectral simulations for linear viscoelastic incompressible flows

  • Zhang, Ling;Ouyang, Jie
    • Interaction and multiscale mechanics
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    • 제5권1호
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    • pp.27-40
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    • 2012
  • The two-dimensional incompressible flow of a linear viscoelastic fluid we considered in this research has rapidly oscillating initial conditions which contain both the large scale and small scale information. In order to grasp this double-scale phenomenon of the complex flow, a multiscale analysis method is developed based on the mathematical homogenization theory. For the incompressible flow of a linear viscoelastic Maxwell fluid, a well-posed multiscale system, including averaged equations and cell problems, is derived by employing the appropriate multiple scale asymptotic expansions to approximate the velocity, pressure and stress fields. And then, this multiscale system is solved numerically using the pseudospectral algorithm based on a time-splitting semi-implicit influence matrix method. The comparisons between the multiscale solutions and the direct numerical simulations demonstrate that the multiscale model not only captures large scale features accurately, but also reflects kinetic interactions between the large and small scale of the incompressible flow of a linear viscoelastic fluid.

Developing Objective Linear Scale Data from Subjective Tests for Consumer Products

  • Ko, Young Chan;Park, Jong-Moon
    • 펄프종이기술
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    • 제48권1호
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    • pp.19-26
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    • 2016
  • In the consumer products industry, it has been highly desirable to develop objective test methods to replace subjective evaluation methods. In developing an objective test method, subjective evaluation data should be on a linear scale. According to Thurstone's theory of comparative judgment, a%-preference from a paired-comparison test can be converted to a linear-scale value. The required number (N) of paired-comparison tests increases dramatically as the number of products increases. This problem should be solved by classifying the total products into several subgroups consisting of 3-4 products in each group. By doing so, it can not only significantly reduce the number of required paired-comparison tests, but it can also obtain more reliable, reproducible data.

He-Ne 레이저의 간섭을 이용한 고정밀 리니어 스케일의 제작에 관한 연구 (A Study on the Manufacturing of High Precision Linear Scale Using He-Ne Laser Interference)

  • 한응교;전병욱;이명호;박두원;노병옥
    • 한국정밀공학회지
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    • 제8권3호
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    • pp.82-92
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    • 1991
  • A study on the manufacturing of High Precision Linear Scalr using He-Ne Laser interference Of late, along with the advancement of precision machining technology, the requirement of super precision measurement increases as time goes on, and the accuracy of standard scale which is a basis of precision measurement has been cognized as a criterion of industrial development in a nationl. In this paper, we described on technology by which we could carve scale lines thru optical method under the condition of laboratory by using the coherence of He-Ne two-mode stabilized laser and in turn, put it to practical use as linear scale for the measurement of length. Hence in this research in the case of setting scale interval to 20 ${\mu}m$, we employed super precision scale-carving device associated with Ar laser and acousto optic modulator in lieu of flashing lamp scale-carving device, and we obtained as experimental result superior linear scales carved within the accuracy of ${\pm}$0.3${\mu}m$.

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LMI 기법을 이용한 시간지연 대규모 불확정성 선형 시스템의 강인 안정성 (Robust Stability of Uncertain Linear Large-scale Systems with Time-delay via LMI Approach)

  • 이희송;김진훈
    • 대한전기학회논문지:전력기술부문A
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    • 제48권10호
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    • pp.1287-1292
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    • 1999
  • In large-scale systems, we frequently encounter the time-delay and the uncertainty, and these should be considered in the design of controller because these are the source of the degradation of the system performance and instability of system. In this paper, we consider the robust stability of the linear large scale systems with the uncertainties and the time-delays. The considered uncertainties are both structured uncertainty and the unstructured uncertainty. Also, the considered time-delays are time-varying having finite time derivative limits. Based on the Lyapunov theorem and the linear matrix inequality(LMI) technique, we present two sufficient conditions that guarantee the robust stability of the system. The conditions are expressed as the LMI forms which can be easily checked their feasibility by using the well-known LMI control toolbox. Finally, we show by two examples that our results are less conservative than the previous results.

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레이저의 간섭무늬를 이용한 리니어 엔코더에 관한 연구 (High resolution Linear Encoder Using Interference Fringe)

  • 박윤창
    • 한국생산제조학회지
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    • 제8권4호
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    • pp.130-135
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    • 1999
  • The main scale of linear encoder greatly effects on the precision of displacement measurement. Especially when needing the long range measurement the length of main scale should be increased accordingly. In this paper we propose a linear encoder that uses laser interference pattern as main scale for long range measurement. The linear encoder is similar to Michelson interferometer excepting that the reference mirror is tilted so as to obtain interference fringe pattern and a grating panel is attached on a quadratic photo diodes. Four kinds of grating having phase difference of 0. $\pi$/4, $\pi$/2, 3$\pi$/4 are arranged on the panel. The experimental results show that signals of quadratic photo diode A, B, {{{{ {-}atop {A } }}}} and {{{{ {- } atop {B } }}}} are cosine wavelike and successive signals have phase difference of $\pi$/4 each other. So the proposed method can achieve improved measurement resolution.

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On Testing Fisher's Linear Discriminant Function When Covariance Matrices Are Unequal

  • Kim, Hea-Jung
    • Journal of the Korean Statistical Society
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    • 제22권2호
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    • pp.325-337
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    • 1993
  • This paper propose two test statistics which enable us to proceed the variable selection in Fisher's linear discriminant function for the case of heterogeneous discrimination with equal training sample size. Simultaneous confidence intervals associated with the test are also given. These are exact and approximate results. The latter is based upon an approximation of a linear sum of Wishart distributions with unequal scale matrices. Using simulated sampling experiments, powers of the two tests have been tabulated, and power comparisons have been made between them.

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리니어 모터를 적응한 공작기계의 열변형 특성에 관한 연구 (A Study on the thermal behaviors of a machine tool with linear motors)

  • 김종진;조동우
    • 한국공작기계학회:학술대회논문집
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    • 한국공작기계학회 2002년도 추계학술대회 논문집
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    • pp.36-40
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    • 2002
  • The development of feed drive system with high speed and accuracy has been a major issue in the machine tool industry. Linear motors can be used as the efficient tool to achieve fast feed mechanism and high accuracy. However. a high speed feed drive system with linear motors can generate heat problems such as the variation of temperature distribution and the resultant thermal stress. In this paper, the important heat sources and the resultant thermal errors are presented. The thermal deformation characteristics of the machine tool with linear motors were identified, which are thermal expansion of linear scale, shrinkage, expansion and bending in the machine tool structure.

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대규모 시스템을 위한 LMI기반 비집중화 슬라이딩 모드 정적 출력 궤환 제어기 설계 (An LMI-based Decentralized Sliding Mode Static Output Feedback Control Design Method for Large Scale Systems)

  • 최환호
    • 제어로봇시스템학회논문지
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    • 제14권4호
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    • pp.381-384
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    • 2008
  • In this paper, we consider the problem of designing decentralized sliding mode static output feedback control laws for a class of large scale systems with mismatched uncertainties. We derive a sufficient condition for the existence of a linear switching surface in terms of constrained linear matrix inequalities(LMIs), and we parameterize the linear switching surfaces in terms of the solution matrices to the given constrained LMI existence conditions. We also give an LMI-based algorithm for designing decentralized switching feedback control laws. Finally, we give a design example in order to show the effectiveness of our method.