• Title/Summary/Keyword: 비선형 예측

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Performance improvement of active noise control using on-line estimation of secondary path transfer function (부가경로 전달함수의 온라인 예측에 의한 능동소음제어의 성능 향상)

  • Kim, Heung-Seob;Sohn, Dong-Gu;Oh, Jae-Eung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.2
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    • pp.281-287
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    • 1997
  • In the conventional inverse modeling method for on-line modeling of the secondary path transfer function, the signal to noise ratio between the arbitrary random signal and the plant noise have to keep at -10 - -20 dB. For these reasons, the modeling can't be exactly implemented by the conventional method alone and the convergence time for modeling becomes too long. In this study, by combining the conventional inverse modeling method with an adaptive line enhancer, or with an adaptive noise canceller, a rigorous transfer functions of secondary path modeling and the control of a primary noise have been implemented simultaneously.

A Roundness Evaluation of Al-6061 Turning by Orthogonal Table and Multiple Linear Regression (직교배열에 의한 선삭과 회귀분석방법에 의한 Al-6061의 진원도 평가)

  • Jang, Sung-Min;Back, Si-Young
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.1
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    • pp.45-50
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    • 2012
  • This paper on analysis of roundness error after boring turning of Al-6061 materials with CNC lathe. Experiment applying turning parameters is based on experimental design method. A design and analysis of experiments is conducted to study the effects of these parameters on the roundness error using the S/N ratio and analysis of ANOVA. Multiple linear regression analysis is applied to compare experimental with predicted data in consideration of roundness error. To fixation pressure and the opening which are a turning parameter, the cutting depth and feed speed respected the objective attainment of dissertation and to be applied the result they investigated.

Adaptive echo canceller combined with speech coder for mobile communication systems (이동통신 시스템을 위한 음성 부호화기와 결합된 적응 반향제거기에 관한 연구)

  • 이인성;박영남
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.23 no.7
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    • pp.1650-1658
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    • 1998
  • This paper describes how to remove echoes effectively using speech parameter information provided form speech coder. More specially, the proposed adaptive echo canceller utilizes the excitation signal or linearly predicted error signal instead of output speech signal of vocoder as the input signal for adaptation algorithm. The normalized least mean ssquare(NLMS) algorithm is used for the adaptive echo canceller. The proposed algorithm showed a fast convergece charactersitcis in the sinulatio compared to the conventional method. Specially, the proposed echo canceller utilizing the excitation signal of speech coder showed about four times fast convergence speed over the echo canceller utilizing the output speech signal of the speech coder for the adaptation input.

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A Study on the Prediction of Fatigue Life by use of Probability Density Function (확률밀도함수를 이용한 피로균열 발생수명 예측에 관한 연구)

  • 김종호
    • Journal of Advanced Marine Engineering and Technology
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    • v.23 no.4
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    • pp.453-461
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    • 1999
  • The estimation of fatigue life at the design stage is very important in order to arrive at feasible and cost effective solutions considering the total lifetime of the structure and machinery compo-nents. In this study the practical procedure of prediction of fatigue life by use of cumulative damage factors based on Miner-Palmgren hypothesis and probability density function is shown with a $135,000m^3$ LNG tank being used as an example. In particular the parameters of Weibull distribution taht determine the stress spectrum are dis-cussed. At the end some of uncertainties associated with fatigue life prediction are discussed. The main results obtained from this study are as follows: 1. The practical procedure of prediction of fatigue life by use of cumulative damage factors expressed in combination of probability density function and S-N data is proposed. 2. The calculated fatigue life is influenced by the shape parameter and stress block. The conser-vative fatigue design can be achieved when using higher value of shape parameter and the stress blocks divded into more stress blocks.

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The Development of an Event Rainfall-Runoff Model in Small Watersheds (홍수 사상에 대한 소유역 강우-유출 모형 개발)

  • 이상호;이길성
    • Water for future
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    • v.27 no.3
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    • pp.145-158
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    • 1994
  • The linear reservoir rainfall-runoff system was developed as a rainfall-runoff event simulation model. It was achieved from large modification of runoff function method. There are six parameters in the model. Hydrologic losses consist of some quantity of initial loss and some ratio of rainfall intensity followed by initial loss. The model has analytical routing equations. Hooke and Jeeves algorithm was used to model calibration. Parameters were estimated for flood events from '84 to '89 at Seomyeon and Munmak stream gauges, and the trends of major parameters were analyzed. Using the trends, verifications were performed for '90 flood event. Because antecedent fainfalls affect initial loss, future researches are required on such effects. The estimation method of major parameters should also be studied for real-time forecasting.

Enhancement of Artillery Simulation Training System by Neural Network (신경망을 이용한 포병모의훈련체계 향상방안)

  • Ryu, Hai-Joon;Ko, Hyo-Heon;Kim, Ji-Hyun;Kim, Sung-Shick
    • Journal of the military operations research society of Korea
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    • v.34 no.1
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    • pp.1-11
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    • 2008
  • A methodology for the improvement of simulation based training system for the artillery is proposed in this paper. The complex nonlinear relationship inherent among parameters in artillery firing is difficult to model and analyze. By introducing neural network based simulation, accurate representation of artillery firing is made possible. The artillery training system can greatly benefit from the improved prediction. Neural networks learning is conducted using the conjugate gradient algorithm. The evaluation of the proposed methodology is performed through simulation. Prediction errors of both regression analysis model and neural networks model are analyzed. Implementation of neural networks to training system enables more realistic training, improved combat power and reduced budget.

Finite Element Analysis to Predict Design Loads of Circular Foundation (원형기초의 설계하중 예측을 위한 유안요소해석)

  • 김성득;김미룡
    • Geotechnical Engineering
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    • v.5 no.1
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    • pp.19-26
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    • 1989
  • In this study, the finite element method for nonlinear problems is developed theroretically to see the design loads of foundation, when the circular plate resting on elasto-viscoplastic soil medium is loaded axisymmetrically. The paper shows that the plastic zone of soil medium is displayed at the near the edge of plate at the first place; when the plastic zone of soil medium is linked around central axis, the external load is termed by allowable load or design load, and then the contact pressure changes abruptly, in this case it is approved to be the risk of shear failure. The results of numerical analysis using the Mohr-Coulomb yield criterion, and experimental analysis for a appropriate safety factor are approximative, but numerical results are smaller than the value based on Terzaghi's theory.

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Analytical Study on the fatigue Behavior of Reinforced Concrete Bridge Piers under Earthquake (지진시 철근콘크리트 교각의 피로거동에 관한 해석적 연구)

  • 김태훈;이상철;신현목
    • Journal of the Korea Concrete Institute
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    • v.13 no.4
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    • pp.389-396
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    • 2001
  • This paper presents an analytical prediction of the fatigue behavior of reinforced concrete bridge piers under earthquake. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. In boundary plane at which each member with different thickness is connected, local discontinuous deformation due to the abrupt change in their stiffness can be taken into account by introducing interface element. The effect of number of load reversals with the same displacement amplitude has been also taken into account to model the reinforcing steel. The proposed numerical method for fatigue behavior of reinforced concrete bridge piers under earthquake will be verified by comparison with reliable experimental results.

Optical Temperature Sensor Based on the Etched Planar Waveguide Bragg Grating Considering Linear Thermo-optic Effect (평면 광도파로 상의 식각 브래그 격자를 이용한 광온도 센서의 개발)

  • Kook-Chan Ahn;Sang-Mae Lee
    • Journal of the Korean Society of Safety
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    • v.16 no.2
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    • pp.121-129
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    • 2001
  • This paper demonstrates the development of optical temperature sensor based on the etched planar waveguide Bragg grating. Topics include design and fabrication of the etched planar waveguide Bragg grating, investigation of the grating reflection characteristics, and temperature measurement capabilities. The typical bandwidth and reflectivity of the surface etched grating has been ~0.2nm and ~7%, respectively, at a wavelength of ~1552nm. The temperature-induced wavelength change of the optical sensor is found to be slightly non-linear over ~20$0^{\circ}C$ temperature range. Theoretical models for the grating response of the sensor based on waveguide and plate deformation theories agree with experiments to within acceptable tolerance.

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The Flight Trajectory of a Boomerang Simulated with Helicopter Theories (회전익 이론을 이용한 부메랑의 비행 궤적 연구)

  • Jang,Se-Myeong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.1
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    • pp.49-57
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    • 2003
  • The flight trajectory of a boomerang is predicted with the momentum theory (actuating disk theory) and the blade element method generally used as tools to analyze in the rotary-wing aerodynamics. Boomerangs made by students are actually compared with the computational results, utilized to get the physical intuition. The transition from helicopter mode to autogyro mode with the gyroscopic precession is observed in numerical analysis and experiment like a 'flying rotor' after the boomerang taking off. The whole system is shown to be highly nonlinear and very sensitive to the initial conditions. Various flight loci may be obtained if we change the parameters.