• 제목/요약/키워드: Response time index

검색결과 446건 처리시간 0.032초

PID제어를 위한 실용적인 기준 모델 제안과 성능개선 (Proposal of Practical Reference-Model and It's Performance Improvement for PID Control)

  • 허정규;양경욱
    • 동력기계공학회지
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    • 제11권3호
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    • pp.66-72
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    • 2007
  • This study proposed new method to decide the reference model necessary for design PID controller. In generally, control design problems using the reference model have the following two factors. One factor is that numerical model of the controlled system can be obtained extremely, and the other is that specification for the closed-loop dynamic performance is pure moderate. Therefore, the control design procedure is essentially based on the partial reference model matching which offers a reasonable method to simplify the design and the controller configuration under the controlled system uncertainty. ITAE(Integral of time-multiplied absolute error) performance index and Kitamori method etc. which were used a reference model method had a limit to settling time and rising time of reference model that it arrived to steady state response according to the controlled system. On this study, if it only knew peak time of overshoot and settling time by measurement signal of the controlled system, it can be made the reference model easily. We proposed new method to improve performance index of the reference model superior to existing reference model index and illustrate the numerical simulation results to show the effectiveness of proposed control method design.

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Sensor selection approach for damage identification based on response sensitivity

  • Wang, Juan;Yang, Qing-Shan
    • Structural Monitoring and Maintenance
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    • 제4권1호
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    • pp.53-68
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    • 2017
  • The response sensitivity method in time domain has been applied extensively for damage identification. In this paper, the relationship between the error of damage identification and the sensitivity matrix is investigated through perturbation analysis. An index is defined according to the perturbation amplify effect and an optimal sensor placement method is proposed based on the minimization of that index. A sequential sub-optimal algorithm is presented which results in consistently good location selection. Numerical simulations with a two-dimensional high truss structure are conducted to validate the proposed method. Results reveal that the damage identification using the optimal sensor placement determined by the proposed method can identify multiple damages of the structure more accurately.

Dynamic response of functionally graded plates with a porous middle layer under time-dependent load

  • Dergachova, Nadiia V.;Zou, Guangping
    • Computers and Concrete
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    • 제27권3호
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    • pp.269-282
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    • 2021
  • A dynamic analytical solution for a simply supported, rectangular functionally graded plate with a porous middle layer under time-dependent load based on a refined third-order shear deformation theory with a cubic variation of in-plane displacements according to the thickness and linear/quadratic transverse displacement is presented. The solution achieved in the trigonometric series form and rests on the Green's function method. Two porosity types and their influence on material properties, and mechanical behavior are considered. The network of pores is assumed to be empty or filled with low-pressure air, and the material properties are calculated using the power-law distribution idealization. Numerical calculations have been carried out to demonstrate the accuracy of the kinematic model for the dynamic problem, the effect of porosity, thickness of porous layers, power-law index, and type of loading on the dynamic response of an imperfect functionally graded material plate.

The Impacts of the COVID-19 Pandemic on the Movement of Composite Stock Price Index in Indonesia

  • ZAINURI, Zainuri;VIPHINDRARTIN, Sebastiana;WILANTARI, Regina Niken
    • The Journal of Asian Finance, Economics and Business
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    • 제8권3호
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    • pp.1113-1119
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    • 2021
  • This study aims to determine the impact of the news coverage of the COVID-19 pandemic on the composite stocks' movement (IHSG) in Indonesia. This study used secondary data of daily time series with an observation range of March 2020-June 2020. This study used three main variables, namely, COVID-19 news, the daily price of a composite stock market index (IHSG), and interest rate. This study clarifies pandemic news into two forms to facilitate quantitative analysis, namely, good news and bad news. Both pandemic news conditions, which have been clarified, are then processed into the index and reprocessed along with two other variables using vector autoregressive (VAR). The results showed that the good news have a dominant effect on developing the composite stock price index (IHSG) in Indonesia during the COVID-19 pandemic. Although the good news dominates the composite stock price index (IHSG) movement in Indonesia, the bad news must also be anticipated. By implementing a series of macroeconomic policies that follow the conditions of the composite stock price index (IHSG) movements on the stock exchange floor, the bad news response can decrease the potential for a decline in investor confidence, so that the financial system's macroeconomic stability is maintained.

Damage evaluation of seismic response of structure through time-frequency analysis technique

  • Chen, Wen-Hui;Hseuh, Wen;Loh, Kenneth J.;Loh, Chin-Hsiung
    • Structural Monitoring and Maintenance
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    • 제9권2호
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    • pp.107-127
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    • 2022
  • Structural health monitoring (SHM) has been related to damage identification with either operational loads or other environmental loading playing a significant complimentary role in terms of structural safety. In this study, a non-parametric method of time frequency analysis on the measurement is used to address the time-frequency representation for modal parameter estimation and system damage identification of structure. The method employs the wavelet decomposition of dynamic data by using the modified complex Morlet wavelet with variable central frequency (MCMW+VCF). Through detail discussion on the selection of model parameter in wavelet analysis, the method is applied to study the dynamic response of both steel structure and reinforced concrete frame under white noise excitation as well as earthquake excitation from shaking table test. Application of the method to building earthquake response measurement is also examined. It is shown that by using the spectrogram generated from MCMW+VCF method, with suitable selected model parameter, one can clearly identify the time-varying modal frequency of the reinforced concrete structure under earthquake excitation. Discussions on the advantages and disadvantages of the method through field experiments are also presented.

실시간 위협에서 Event 유형의 정형화 설계 및 구현 (Standardization Model and Implementation of Event Type in Real Time Cyber Threat)

  • 이동휘;이동춘;김귀남
    • 융합보안논문지
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    • 제6권4호
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    • pp.67-73
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    • 2006
  • 실시간 사이버위협에서 정형화 방법은 각 보안장비의 이벤트를 실시간 분석하여 인터넷 웜, 바이러스, 해킹 등의 사이버공격에 대한 네트워크 이상 징후를 임계치와 상관관계를 틀 통하여 탐지하고, 동 평가결과의 통계분석을 통해 정형화 방안 기능을 부여하고 실효성 있는 사이버공격대응시스템을 구축하는데 있다. 본 논문은 우선 위협지표 산출과 동 지표의 합산을 통한 위협평가 및 조기 경보 과정의 패키지화로 만들고, 사이버 위협 지표 계산의 기준을 설정한다. 특히 보안사고 발생 시 각 보안장비의 이벤트와 트래픽 양에 대한 정의 및 데이터베이스 입력 방법을 구체화하여 실시간 대응 및 조기예경보체계의 초석이 가능한 정형화 방안을 제시한다. 분석을 위해 축적한 90일간의 데이터 임계치 설정작업을 통해 보다 정확한 적용 값을 계산한다. 산출한 값을 토대로 정형화가 가능한 보안이벤트 정보를 표준데이터로 적용, 각 보안장비 및 HoneyNet 시스템, 기타 취약정보 등과의 상관관계를 분석하여 보안이벤트 표준지수를 산출한다.

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지연요소를 수반하는 일차계통의 패러미터 추정에 관한 연구 (A Study of Parameter Estimation for First Order System with Dead Time)

  • 하주식
    • 전기의세계
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    • 제18권1호
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    • pp.15-23
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    • 1969
  • A lot of recent researches have shown that a Pseudo Random Binary Signal is a quite effective test signal to measure the impulse response of a plant. Generally speaking, however, such a response itself is not satisfactory to determine the appropriate control parameters or control inputs. Here, the author intends to estimate the unknown parameters of the First Order Plant with Dead Time by means of correlation method using M-sequence signal. The time constant T and the dead time L of the plant are eatimated with one tracking loop by automatically adjusting delay time .tau. of M-sequence signal according to variations of T and L. In this paper, a three level M-sequence signal is used as a test signal in order to avoid troublesome operations to calculate partial derivatives of a given performance index with respect to the parameters which are usually required in the Model Method. Several experiments with analogue computer using low pass filters as averaging circuits showed good results as expected.

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Seismic response of RC frames under far-field mainshock and near-fault aftershock sequences

  • Hosseini, Seyed Amin;Ruiz-Garcia, Jorge;Massumi, Ali
    • Structural Engineering and Mechanics
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    • 제72권3호
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    • pp.395-408
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    • 2019
  • Engineered structures built in seismic-prone areas are affected by aftershocks in addition to mainshocks. Although aftershocks generally are lower in magnitude than that of the mainshocks, some aftershocks may have higher intensities; thus, structures should be able to withstand the effect of strong aftershocks as well. This seismic scenario arises for far-field mainshock along with near-field aftershocks. In this study, four 2D reinforced concrete (RC) frames with different numbers of stories were designed in accordance with the current Iranian seismic design code. As a way to evaluate the seismic response of the case-study RC frames, the inter-story drift ratio (IDR) demand, the residual inter-story drift ratio (RIDR) demand, the Park-Ang damage index, and the period elongation ratio can be useful engineering demand parameters for evaluating their seismic performance under mainshock-aftershock sequences. The frame models were analyzed under a set of far-field mainshock, near-fault aftershocks seismic sequences using nonlinear dynamic time-history analysis to investigate the relationship among IDR, RIDR, Park-Ang damage index and period ratio experienced by the frames. The results indicate that the growth of IDR, RIDR, Park-Ang damage index, and period ratio in high-rise and short structures under near-fault aftershocks were significant. It is evident that engineers should consider the effects of near-fault aftershocks on damaged frames that experience far-field mainshocks as well.

VAR 모형을 이용한 주가, 금리, 물가, 주택가격의 관계에 대한 실증연구 (An Empirical Analysis on the Relationship between Stock Price, Interest Rate, Price Index and Housing Price using VAR Model)

  • 김재경
    • 유통과학연구
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    • 제11권10호
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    • pp.63-72
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    • 2013
  • Purpose - This study analyzes the relationship and dynamic interactions between stock price index, interest rate, price index, and housing price indices using Korean monthly data from 2000 to 2013, based on a VAR model. This study also examines Granger causal relationships among these variables in order to determine whether the time series of one is useful in forecasting another, or to infer certain types of causal dependency between stochastic variables. Research design, data, and methodology - We used Korean monthly data for all variables from 2000: M1 to 2013: M3. First, we checked the correlations among different variables. Second, we conducted the Augmented Dickey-Fuller (ADF) test and the co-integration test using the VAR model. Third, we employed Granger Causality tests to quantify the causal effect from time series observations. Fourth, we used the impulse response function and variance decomposition based on the VAR model to examine the dynamic relationships among the variables. Results - First, stock price Granger affects interest rate and all housing price indices. Price index Granger, in turn, affects the stock price and six metropolitan housing price indices. However, none of the Granger variables affect the price index. Therefore, it is the stock markets (and not the housing market) that affects the housing prices. Second, the impulse response tests show that maximum influence on stock price is its own, and though it is influenced a little by interest rate, price index affects it negatively. One standard deviation (S.D.) shock to stock price increases the housing price by 0.08 units after two months, whereas an impulse shock to the interest rate negatively impacts the housing price. Third, the variance decomposition results report that the shock to the stock price accounts for 96% of the variation in the stock price, and the shock to the price index accounts for 2.8% after two periods. In contrast, the shock to the interest rate accounts for 80% of the variation in the interest rate after ten periods; the shock to the stock price accounts for 19% of the variation; however, shock to the price index does not affect the interest rate. The housing price index in 10 periods is explained up to 96.7% by itself, 2.62% by stock price, 0.68% by price index, and 0.04% by interest rate. Therefore, the housing market is explained most by its own variation, whereas the interest rate has little impact on housing price. Conclusions - The results of the study elucidate the relationship and dynamic interactions among stock price index, interest rate, price index, and housing price indices using VAR model. This study could help form the basis for more appropriate economic policies in the future. As the housing market is very important in Korean economy, any changes in house price affect the other markets, thereby resulting in a shock to the entire economy. Therefore, the analysis on the dynamic relationships between the housing market and economic variables will help with the decision making regarding the housing market policy.

마이크 사용시 강의실내의 음향특성 (The Acoustic Character of Classroom as Using Microphone)

  • 이채봉;강대기
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2003년도 춘계학술대회논문집
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    • pp.786-790
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    • 2003
  • The purpose of this research is to observe that the acoustic characters of classroom have some difference by several conditions. TSP has used to measure impulse response and such physical indexes as RT(Reverberation Time), D$\sub$50/, and STI(Speech-Transmission-Index) are computed by it. we investigate difference under some conditions such as when students were present at each classroom and when was not so, and when professor used a microphone and unused it. In this study, we found that reverberation time when people take a seat is lower than was not so. we wish to help one who work for construction industry, as they build a kind of classroom

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