• Title/Summary/Keyword: Parametric error

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Continuous Speech Recognition based on Parmetric Trajectory Segmental HMM (모수적 궤적 기반의 분절 HMM을 이용한 연속 음성 인식)

  • 윤영선;오영환
    • The Journal of the Acoustical Society of Korea
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    • v.19 no.3
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    • pp.35-44
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    • 2000
  • In this paper, we propose a new trajectory model for characterizing segmental features and their interaction based upon a general framework of hidden Markov models. Each segment, a sequence of vectors, is represented by a trajectory of observed sequences. This trajectory is obtained by applying a new design matrix which includes transitional information on contiguous frames, and is characterized as a polynomial regression function. To apply the trajectory to the segmental HMM, the frame features are replaced with the trajectory of a given segment. We also propose the likelihood of a given segment and the estimation of trajectory parameters. The obervation probability of a given segment is represented as the relation between the segment likelihood and the estimation error of the trajectories. The estimation error of a trajectory is considered as the weight of the likelihood of a given segment in a state. This weight represents the probability of how well the corresponding trajectory characterize the segment. The proposed model can be regarded as a generalization of a conventional HMM and a parametric trajectory model. The experimental results are reported on the TIMIT corpus and performance is show to improve significantly over that of the conventional HMM.

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Modeling of a Building System and its Parameter Identification

  • Park, Herie;Martaj, Nadia;Ruellan, Marie;Bennacer, Rachid;Monmasson, Eric
    • Journal of Electrical Engineering and Technology
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    • v.8 no.5
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    • pp.975-983
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    • 2013
  • This study proposes a low order dynamic model of a building system in order to predict thermal behavior within a building and its energy consumption. The building system includes a thermally well-insulated room and an electric heater. It is modeled by a second order lumped RC thermal network based on the thermal-electrical analogy. In order to identify unknown parameters of the model, an experimental procedure is firstly detailed. Then, the different linear parametric models (ARMA, ARX, ARMAX, BJ, and OE models) are recalled. The parameters of the parametric models are obtained by the least square approach. The obtained parameters are interpreted to the parameters of the physically based model in accordance with their relationship. Afterwards, the obtained models are implemented in Matlab/Simulink(R) and are evaluated by the mean of the sum of absolute error (MAE) and the mean of the sum of square error (MSE) with the variable of indoor temperature of the room. Quantities of electrical energy and converted thermal energy are also compared. This study will permit a further study on Model Predictive Control adapting to the proposed model in order to reduce energy consumption of the building.

A Parametric Study of the Hemming Process by Finite Element Analysis (유한요소해석에 의한 헤밍 공정 변수연구)

  • Kim, Hyung-Jong;Choi, Won-Mog;Lim, Jae-Kyu;Park, Chun-Dal;Lee, Woo-Hong;Kim, Heon-Young
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.2
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    • pp.149-157
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    • 2004
  • Implicit finite element analysis of the flat surface-straight edge hemming process is performed by using a commercial code ABAQUS/Standard. Methods of finite element modeling for springback simulation and contact pair definition are discussed. An optimal mesh system is chosen through the error analysis that is based on the smoothing of discontinuity in the state variables. This study has focused on the investigation of the influence of process parameters in flanging, pre-hemming and main hemming on final hem quality, which can be defined by turn-down, warp and roll-in. The parameters adopted in this parametric study are flange length, flange angle, flanging die corner radius, face angle and insertion angle of pre-hemming punch, and over-stroke of pre-hemming and main hemming punches.

A Comparative Study on Lowflow Quantiles Estimation in Han River Basin (한강유역의 확률갈수량 추정기법 비교연구)

  • Kim, Kyung-Duk;Kim, Don-Soo;Heo, Jun-Haeng;Kim, Kyu-Ho
    • Journal of Korea Water Resources Association
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    • v.36 no.2
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    • pp.315-324
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    • 2003
  • Stream flow data was analyzed for determining the lowflow which is the standard for river maintenance flow. Lowflow quantiles were estimated based on the parametric and nonparametric methods and two methods were compared by Monte Carlo simulation study. As the results of the parametric method, three probability distributions such as gamma-2, lognormal-2 and Weibull-2, are selected as appropriate models for stream flow data of 13 stations in Han River Basins. According to simulation results, relative bias (RBIAS) and relative root mean square error (RRMSE) of the lowflow quantiles are the smallest when the applied and population models are the same. The fame statistical properties from the nonparametric models are good within the interpolation range. Among 7 bandwidth selectors used in this study, the RRMSEs of the Park and Marron method (PM) are the smallest while those of the Shoaler and Jones method (SJ) are the largest.

Are theoretically calculated periods of vibration for skeletal structures error-free?

  • Mehanny, Sameh S.F.
    • Earthquakes and Structures
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    • v.3 no.1
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    • pp.17-35
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    • 2012
  • Simplified equations for fundamental period of vibration of skeletal structures provided by most seismic design provisions suffer from the absence of any associated confidence levels and of any reference to their empirical basis. Therefore, such equations may typically give a sector of designers the false impression of yielding a fairly accurate value of the period of vibration. This paper, although not addressing simplified codes equations, introduces a set of mathematical equations utilizing the theory of error propagation and First-Order Second-Moment (FOSM) techniques to determine bounds on the relative error in theoretically calculated fundamental period of vibration of skeletal structures. In a complementary step, and for verification purposes, Monte Carlo simulation technique has been also applied. The latter, despite involving larger computational effort, is expected to provide more precise estimates than FOSM methods. Studies of parametric uncertainties applied to reinforced concrete frame bents - potentially idealized as SDOF systems - are conducted demonstrating the effect of randomness and uncertainty of various relevant properties, shaping both mass and stiffness, on the variance (i.e. relative error) in the estimated period of vibration. Correlation between mass and stiffness parameters - regarded as random variables - is also thoroughly discussed. According to achieved results, a relative error in the period of vibration in the order of 19% for new designs/constructions and of about 25% for existing structures for assessment purposes - and even climbing up to about 36% in some special applications and/or circumstances - is acknowledged when adopting estimates gathered from the literature for relative errors in the relevant random input variables.

A Robust State Feedback Control of Gimbal System with Parametric Uncertainty (불확실성 파라미터를 포함하는 김발시스템의 상태궤환 강인제어기 설계)

  • Jeon, YeongBeom;Choi, WooSeok;Han, JiHoon;Lee, SungWoo;Kang, TaeHa
    • Journal of the Institute of Electronics and Information Engineers
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    • v.52 no.8
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    • pp.140-147
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    • 2015
  • In this paper, we propose a state feedback robust controller of 2-axis gimbal system which have bounded parametric uncertainty. The proposed controller is robust against dynamics variations of gimbal system and contains a dynamic compensator in order to improve a steady state error and a transient response. The stability of the closed-loop system is proved by Lyapunov approach. The performance of the proposed method is demonstrated by simulation on a 2-axis gimbal system.

Robust Control of the Nonlinear Hydraulic Servo System Using a PID Control Technique (PID 제어 기술을 이용한 비선형 유압 시스템의 강인 제어)

  • Yu, Sam-Hyeon;Lee, Jong-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.5
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    • pp.850-856
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    • 2001
  • Even though the hydraulic servo system has been widely used in industrial and military equipments since it has a lot of advantages, it is not easy to design controller due to the high nonlinearities and the parametric uncertainties. The dynamic behavior of the real process in the hydraulic servo system differs from that described by its model because the model is linearized. Another reason of the difference is caused by the variety of parameters, since the system parameters of the dynamic equation are affected by the operating conditions such as temperature and pressure. In this study, the designing process of the MRNC with a PID compensator is introduced and applied to the load sensing hydraulic servo system. The results show that the designed controller guarantees the robust control performance despite of both the nonlinearities and the parametric uncertainties.

A parametric bootstrap test for comparing differentially private histograms (모수적 부트스트랩을 이용한 차등정보보호 히스토그램의 동질성 검정)

  • Son, Juhee;Park, Min-Jeong;Jung, Sungkyu
    • The Korean Journal of Applied Statistics
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    • v.35 no.1
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    • pp.1-17
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    • 2022
  • We propose a test of consistency for two differentially private histograms using parametric bootstrap. The test can be applied when the original raw histograms are not available but only the differentially private histograms and the privacy level α are available. We also extend the test for the case where the privacy levels are different for different histograms. The resident population data of Korea and U.S in year 2020 are used to demonstrate the efficacy of the proposed test procedure. The proposed test controls the type I error rate at the nominal level and has a high power, while a conventional test procedure fails. While the differential privacy framework formally controls the risk of privacy leakage, the utility of such framework is questionable. This work also suggests that the power of a carefully designed test may be a viable measure of utility.

Sensorless Speed Control System Using a Neural Network

  • Huh Sung-Hoe;Lee Kyo-Beum;Kim Dong-Won;Choy Ick;Park Gwi-Tae
    • International Journal of Control, Automation, and Systems
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    • v.3 no.4
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    • pp.612-619
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    • 2005
  • A robust adaptive speed sensorless induction motor direct torque control (DTC) using a neural network (NN) is presented in this paper. The inherent lumped uncertainties of the induction motor DTC system such as parametric uncertainty, external load disturbance and unmodeled dynamics are approximated by the NN. An additional robust control term is introduced to compensate for the reconstruction error. A control law and adaptive laws for the weights in the NN, as well as the bounding constant of the lumped uncertainties are established so that the whole closed-loop system is stable in the sense of Lyapunov. The effect of the speed estimation error is analyzed, and the stability proof of the control system is also proved. Experimental results as well as computer simulations are presented to show the validity and efficiency of the proposed system.

A Robust Control of Robot Manipulators with Integral Control (적분제어를 포함하는 로봇 매니퓰레이터의 강인제어)

  • Shin, Eui-Seok;Lee, Kang-Woong
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.35S no.8
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    • pp.32-38
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    • 1998
  • In this paper, we design a robust controller for trajectory control of n-link robot manipulators with bounded parametric uncertainties. The proposed control scheme with integral control improves tracking error due to limit of the robust feedback gains and use of continuous control input for chattering rejection. The integral of the tracking error is augmented to the error system equation and the stability of the closed-loop system is achieved. The performance of the proposed method is demonstrated by simulation on a 2-link manipulator.

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