• Title, Summary, Keyword: Transfer function

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Road Noise Estimation Based on Transfer Path Analysis Using a Simplified Tire Vibration Transfer Model (단순화된 타이어 진동전달 모델의 전달경로분석법을 이용한 로드노이즈 예측기술 개발)

  • Shin, Taejin;Park, Jongho;Lee, Sangkwon;Shin, Gwangsoo;Hwang, Sungwook
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.2
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    • pp.176-184
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    • 2013
  • Quantification of road noise is a challenging issue in the development of tire noise since its transfer paths are complicated. In this paper, a simplified model to estimate the road noise is developed. Transfer path of the model is from wheel to interior. The method uses the wheel excitation force estimated throughout inverse method. In inversion procedure, the Tikhonov regularization method is used to reduce the inversion error. To estimate the wheel excitation force, the vibration of knuckle is measured and transfer function between knuckle and wheel center is also measured. The wheel excitation force is estimated by using the measured knuckle vibration and the inversed transfer function. Finally interior noise due to wheel force is estimated by multiplying wheel excitation force in the vibro-acoustic transfer function. This vibro-acoustic transfer function is obtained throughout measurement. The proposed method is validated by using cleat excitation method. Finally, it is applied to the estimation of interior noise of the vehicle with different types of tires during driving test.

Dynamic analysis of TRIGA Mark-II reactor (TRIGA Mark-II 원자로의 동특성 해석)

  • 이양수
    • 전기의세계
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    • v.14 no.6
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    • pp.8-13
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    • 1965
  • The TRIGA Mark-II Reactor is very simple to analyze the dynamic characteristics, so that the heat transfer function of the reactor fuel rod is able to be considered as a over-all feedback transfer function. The heat transfer dynamics of the fuel rod is derived under some assumptions. And the over-all reactor transfer function is analytically calcu- lated and it is compared with the measured value. The reactor dynamics and the stability are analyzed by means of the Root-Locus and the Nyquist.

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Estimation of rail irregularity using wavelet transfer function (웨이브렛 전달함수를 이용한 궤도틀림 추정)

  • Yoon, Seok-Jun;Choi, Bai-Sung;Lee, Hyeung-Jin;Kim, Man-Cheol;Choi, Sung-Hoon;Shin, Soo-Bong
    • Proceedings of the KSR Conference
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    • pp.330-337
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    • 2010
  • This paper shows an algorithm for identifying track irregularities using wavelet transfer function along the railway. An equivalent SISO wavelet transfer function is defined using continuous wavelet transform by the measured track geometry and acceleration at a bogie of a train. The estimated track geometry is made by inverse continuous wavelet transform from the regressed signals of measured acceleration signal and the pre-defined wavelet transfer function. The estimated rail irregularity geometry is evaluated by the coherence function and comparison of FRF(Frequency Response Function). As a result of evaluated outcome, This algorithm is regarded as appropriate for estimation of rail irregularity.

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Transfer Function Model Forecasting of Sea Surface Temperature at Yeosu in Korean Coastal Waters (전이함수모형에 의한 여수연안 표면수온 예측)

  • Seong, Ki-Tack;Choi, Yang-Ho;Koo, Jun-Ho;Lee, Mi-Jin
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.20 no.5
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    • pp.526-534
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    • 2014
  • In this study, single-input transfer function model is applied to forecast monthly mean sea surface temperature(SST) in 2010 at Yeosu in Korean coastal waters. As input series, monthly mean air temperature series for ten years(2000-2009) at Yeosu in Korea is used, and Monthly mean SST at Yeosu station in Korean coastal waters is used as output series(the same period of input). To build transfer function model, first, input time series is prewhitened, and then cross-correlation functions between prewhitened input and output series are determined. The cross-correlation functions have just two significant values at time lag at 0 and 1. The lag between input and output series, the order of denominator and the order of numerator of transfer function, (b, r, s) are identified as (0, 1, 0). The selected transfer function model shows that there does not exist the lag between monthly mean air temperature and monthly mean SST, and that transfer function has a first-order autoregressive component for monthly mean SST, and that noise model was identified as $ARIMA(1,0,1)(2,0,0)_{12}$. The forecasted values by the selected transfer function model are generally $0.3-1.3^{\circ}C$ higher than actual SST in 2010 and have 6.4 % mean absolute percentage error(MAPE). The error is 2 % lower than MAPE by ARIMA model. This implies that transfer function model could be more available than ARIMA model in terms of forecasting performance of SST.

Sensitivity Analysis Using TPA for Slosh Noise of Fuel Tank (TPA 방법을 이용한 연료탱크의 슬로싱 소음에 관한 민감도 해석)

  • Cha, Hee-Bum;Yoon, Seong-Ho
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.8
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    • pp.766-770
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    • 2007
  • Fuel sloshing in a vehicle fuel tank generates a reluctant low frequency noise, called slosh noise. To reduce slosh noise, whilst many approaches have used the Computational Fluid Dynamics method to first identify fuel behavior in a fuel tank, this paper applies the Transfer Path Analysis method. It is to find contribution of each transfer path from noise transfer function, vibration transfer function and acceleration. Then the final goal is to attenuate slosh noise by controlling them. To this aim, two types of models are studied. One is the decoupled model in which some of connection points of the fuel tank with the vehicle underbody are separated. The other is the modified model which is created by changing noise transfer function and acceleration from the original model. The analysis and validation test results show that the transfer path analysis can be an approach to enhancing slosh noise.

Sensitivity Analysis using TPA for Slosh Noise of Fuel Tank (TPA 방법을 이용한 연료탱크의 슬로싱 소음에 관한 민감도 해석)

  • Cha, Hee-Bum;Yoon, Seong-Ho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.356-360
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    • 2007
  • Fuel sloshing in a vehicle fuel tank generates a reluctant low frequency noise, called slosh noise. To reduce slosh noise, whilst many approaches have used the Computational Fluid Dynamics method to first identify fuel behavior in a fuel tank, this paper applies the Transfer Path Analysis method. It is to find contribution of each transfer path from noise transfer function, vibration transfer function and acceleration. Then the final goal is to attenuate slosh noise by controlling them. To this aim, two types of models are studied. One is the decoupled model in which some of connection points of the fuel tank with the vehicle underbody are separated. The other is the modified model which is created by changing noise transfer function and acceleration from the original model. The analysis and validation test results show that the transfer path analysis can be an approach to enhancing slosh noise.

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A Study on the Identification of Underdamped Process Control System (과소제동 공정제어시스템의 식별에 대한 연구)

  • Seo, Byeong-Seol
    • Journal of the Korean Society for Precision Engineering
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    • v.4 no.3
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    • pp.35-43
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    • 1987
  • A new analytic method for the identification of process control system is presented. A second and a third order transfer function are considered as the estimated model function. For the second order transfer function, the new method is compared with the exisiting ones, simulation results show that the new method is superior to the existing ones. And also, In case of the third order transfer function which is difficult to analyze mathematically, system identification is tried.

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Analysis of Optical Transfer Function and Phase Error of the Modified Triangular Interferometer

  • Kim, Soo-Gil;Ryeom, Jeong-Duk
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.1
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    • pp.10-18
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    • 2007
  • We synthesize and analyze the optical transfer function(OTF) of the modified triangular interferometer(MTI) using two-pupil synthesis method and we present the optimal MTI, which can obtain any bipolar function by combining a wave plate and a linear polarizer. Also, we analyze its potential phase error sources caused by polarization components.

Inflow Noise Characteristics of the Sensor in Low Wave Number Region Using Transfer Function (전달함수를 이용한 저파수 영역에서의 센서 유입 소음 특성 연구)

  • Park, Ji-hye;Lee, Jongkil;Shin, Ku-kyun;Cho, Chi-yong
    • 대한공업교육학회지
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    • v.34 no.1
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    • pp.238-251
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    • 2009
  • The noise itself that affects the sensor array is defined as the noise which happens in the place where the system is installed and the circumference noise which comes from the ocean. The array structure for detecting acoustic signal in the underwater effected turbulent layer flow noise. In this paper to design the conformal array spectral density function was introduced and several cases of flow induced noise which affect transfer function were simulated. Modified Corcos wall pressure model was used as turbulent boundary layer flow noise. The effect of noise has been reduced as integrated sum of transfer function has been reduced by decreasing elastomer thickness and density when kx is in low wave number area. Also the characteristics of transfer function by Corcos wall pressure displayed the product of frequency density function. This simulation results can be applied to the conformal array design in unmmaned underwater vehicle in the near future.

Modeling of Time Delay Systems using Exponential Analysis Method

  • Iwai, Zenta;Mizumoto, Ikuro;Kumon, Makoto;Torigoe, Ippei
    • 제어로봇시스템학회:학술대회논문집
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    • pp.2298-2303
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    • 2003
  • In this paper, very simple methods based on the exponential analysis are presented by which transfer function models for processes can easily be obtained. These methods employ step responses or impulse responses of the processes. These can also give a more precise transfer function model compared to the well-known graphical methods. Transfer functions are determined based on Prony method, which is one of the oldest and the most representative methods in the exponential analysis. Here, the method is reformed and applied to obtain the so-called low-order transfer function with pure time delay from the data of the step response. The effectiveness of the proposed method is examined through several numerical examples and experiments of the 2-tank level control process.

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