• Title/Summary/Keyword: linear error equation

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The State of Charge Estimation for Lithium-Polymer Battery using a PI Observer (PI 상태관측기를 이용한 리튬폴리머 배터리 SOC 추정)

  • Lee, Junwon;Jo, Jongmin;Kim, Sungsoo;Cha, Hanju
    • The Transactions of the Korean Institute of Power Electronics
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    • v.20 no.2
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    • pp.175-181
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    • 2015
  • In this study, a lithium polymer battery (LiPB) is simply expressed by a primary RC equivalent model. The PI state observer is designed in Matlab/Simulink. The non-linear relationship with the OCV-SOC is represented to be linearized with 0.1 pu intervals by using battery parameters obtained by constant-current pulse discharge. A state equation is configured based on battery parameters. The state equation, which applied Peukert's law, can estimate SOC more accurately. SOC estimation capability was analyzed by utilizing reduced Federal Test Procedure (FTP-72) current profile and using a bi-directional DC-DC converter at temperature ($25^{\circ}C$). The PI state observer, which is designed in this study, indicated a SOC estimation error rate of ${\pm}2%$ in any of the initial SOC states. The PI state observer confirms a strong SOC estimation performance despite disturbances, such as modeling errors and noise.

Maneuverability Analysis of a Ship by System Identification Technique (시스템 검증법에 의한 조종성능(操縱性能) 해석(解析))

  • Chang-Gu,Kang;Sang-Hyun,Suh;Jae-Shin,Kim
    • Bulletin of the Society of Naval Architects of Korea
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    • v.21 no.4
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    • pp.10-20
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    • 1984
  • When the hydrodynamic coefficients of the ship maneuvering equation are estimated by captive model test, it is difficult to take account of the scale effect between model and full scale ship. This scale effect problem can be overcome by processing the sea trial data with system identification. Extended Kalman filter is used as a system identification technique for the modification of the simulation equation as well as the estimation of hydrodynamic coefficients The phenomena of simultaneous drifting of linear coefficients occur. It is confirmed that two coefficients in each pair-$(Y_v',\;Y_r'-m'u'),\;(N_v',\;N_r')$-are simultaneously drifting and all 4 coefficients are drifting together. Particularly simultaneous drifting and 2 coefficients in each pair is more significant. It is also shown that the simultaneous drifting of 4 coefficients can be reduced by choosing the input data which have the random v'/r' curve and 4 coefficients are estimated within $2{\sim}4%$ error, which may be noise level. So, it is recommended to operate the rudder randomly in sea trial or model test for the application of system identification technique.

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Development of a neural network method for measuring the energy spectrum of a pulsed electron beam, based on Bremsstrahlung X-Ray

  • Sohrabi, Mohsen;Ayoobian, Navid;Shirani, Babak
    • Nuclear Engineering and Technology
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    • v.53 no.1
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    • pp.266-272
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    • 2021
  • In the pulsed electron beam generators, such as plasma focus devices and linear induction accelerators whose electron pulse width is in the range of nanosecond and less, as well as in cases where there is no direct access to electron beam, like runaway electrons in Tokamaks, measurement of the electron energy spectrum is a technical challenge. In such cases, the indirect measurement of the electron spectrum by using the bremsstrahlung radiation spectrum associated with it, is an appropriate solution. The problem with this method is that the matrix equation between the two spectrums is an ill-conditioned equation, which results in errors of the measured X-ray spectrum to be propagated with a large coefficient in the estimated electron spectrum. In this study, a method based on the neural network and the MCNP code is presented and evaluated to recover the electron spectrum from the X-ray generated by collision of the electron beam with a target. Multilayer perceptron network showed good accuracy in electron spectrum recovery, so that for the X-ray spectrum with errors of 3% and 10%, the network estimated the electron spectrum with an average standard error of 8% and 11%, on all of the energy intervals.

An Adaptive IIR Pre-equalizer for Terrestrial DTV Transmitters (지상파 DTV 송신기를 위한 적응 IIR 전치등화기)

  • Kim Hyoung-Nam;Kim Wan-Jin;Kwon Dae-Ken
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.3A
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    • pp.328-336
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    • 2006
  • A novel pre-equalization method for terrestrial DTV transmitters is presented. A pre-equalizer has been used in transmitters to correct group delay and amplitude distortions caused by a channel filter. In the proposed pre-equalizer, an equation-error adaptive IIR filtering scheme is adopted unlike the conventional pre-equalization using FIR filtering schemes. The pole-zero modelling property of IIR filters improves the signal-to-noise ratio and may deal with diverse linear distortions existing in DTV transmitters as well as the channel filter distortion. Simulation results show that the proposed IIR pre-equalizer performs better than the FIR pre-equalizer in terms of the residual mean-square error.

NOVEL GEOMETRIC PARAMETERIZATION SCHEME FOR THE CERTIFIED REDUCED BASIS ANALYSIS OF A SQUARE UNIT CELL

  • LE, SON HAI;KANG, SHINSEONG;PHAM, TRIET MINH;LEE, KYUNGHOON
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.25 no.4
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    • pp.196-220
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    • 2021
  • This study formulates a new geometric parameterization scheme to effectively address numerical analysis subject to the variation of the fiber radius of a square unit cell. In particular, the proposed mesh-morphing approach may lead to a parameterized weak form whose bilinear and linear forms are affine in the geometric parameter of interest, i.e. the fiber radius. As a result, we may certify the reduced basis analysis of a square unit cell model for any parameters in a predetermined parameter domain with a rigorous a posteriori error bound. To demonstrate the utility of the proposed geometric parameterization, we consider a two-dimensional, steady-state heat conduction analysis dependent on two parameters: a fiber radius and a thermal conductivity. For rapid yet rigorous a posteriori error evaluation, we estimate a lower bound of a coercivity constant via the min-θ method as well as the successive constraint method. Compared to the corresponding finite element analysis, the constructed reduced basis analysis may yield nearly the same solution at a computational speed about 29 times faster on average. In conclusion, the proposed geometric parameterization scheme is conducive for accurate yet efficient reduced basis analysis.

Measurement of High Electric Field Using Linear Electric-Optic Effect of Crystalline SiO$_2$ (SiO$_2$의 전기 광학 효과를 이용한 고전계 측정)

  • 김요희;이대영
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.17 no.2
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    • pp.142-152
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    • 1992
  • This paper presentes a new method to measure high electric field (or high voltage) by using crystalline SiO2 which has very high half wave voltage. There are many difficulties in measuring high electric field using other crystals which have generally low half wave voltage.By applying Stokes parameter and Mueller matrix. We derive optical modulation equation in the sensor which is composed of a polarizer, and Mueller matrix, we derive optical modulation equation in the sensor which is composed of a polarizer, a Pokels material, and an analyzer, We theoretically analyzed electro-optic effect, and calculated the phase retardation and half wave volt age of the birefringent material. The designed optical valtage sensor has very excellent linearity up to 20KV without divided volt-age. The maximum error was measured within 3%. Before annealing of Sio2 crystal, the maximum variation of the output voltage is 7.5% with varying temperature from \ulcorner20˚c to 60˚c. But, after annealing of SiO2 crystal, the output voltage variation is improved within 1%error.

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Analysis of Wave Transmission Characteristics on the TTP Submerged Breakwater Using a Parabolic-Type Linear Wave Deformation Model

  • Jeong, Jin-Hwan;Kim, Jin-Hoon;Lee, Jung-Lyul
    • Journal of Ocean Engineering and Technology
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    • v.35 no.1
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    • pp.82-90
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    • 2021
  • Owing to the advantages of assuring the best views and seawater exchange, submerged breakwaters have been widely installed along the eastern coast of Korea in recent years. It significantly contributes to promoting the advancement of shorelines by partially inhibiting incident wave energy. Observations were carried out by a pressure-type wave gauge in the Bongpo Beach to evaluate the coefficients of wave transmission via a submerged breakwater, and the results obtained were compared with those of existing conventional equations on the transmission coefficient derived from hydraulic experiments. After reviewing the existing equations, we proposed a transmission coefficient equation in terms of an error function. Although it exhibited robust relationships with the crest height and breaking coefficient, deviations from the observed data were evident and considered to be triggered by the difference in the incident wave climate. Therefore, in this study, we conducted a numerical experiment to verify the influence of wave period on the coefficients of wave transmission, in which we adopted a parabolic-type mild-slope equation model. Consequently, the deviation from calculated results appears to practically cover all deviation range in the observed data. The wave period and direction of the incident wave increased, the transmission coefficient decreased, and the wave direction was determined to demonstrate a relatively significant influence on the transmission coefficient. It was inferred that this numerical study is expected to be used practically in evaluating the design achievement of the submerged breakwater, which is adopted as a countermeasure to coastal beach erosion.

Iterative Target Localization Method for Distributed MIMO Radar System (반복적 연산을 이용하는 Distributed MIMO 레이다 시스템의 위치 추정 기법)

  • Shin, Hyuksoo;Chung, Young-Seek;Yang, Hoon-Gee;Kim, Jong-mann;Chung, Wonzoo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.28 no.10
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    • pp.819-824
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    • 2017
  • This paper presents a target localization scheme for distributed Multi-input Multi-output(MIMO) radar system using ToA measurements obtained from multiple transmitter and receiver pairs. The proposed method can locate the target from an arbitrary initial point by iteratively finding the Taylor linear approximation equation. The simulation results show that proposed method achieves the better mean square error(MSE) performance than the existing target localization methods, and furthermore, attains Cramer-Rao Lower Bound(CRLB).

A Stability Analysis of the Magnetic Bearing System Subject to Sensor dislocation Error -Discussion on Nonlinear Magnetic Force Model- (센서의 설치 오차에 따른 자기베어링 지지 로터계의 안정도에 관한 연구 -비선형 자기력 모델에 대한 고찰-)

  • 정재일;김종원
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.799-805
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    • 1996
  • In many cases, the magnetic farce model is linearized at the origin in designing the controller of a magnetic bearing system. However. this linear assumption is violated by the unmodeled nonlinear effect such as sensor dislocation and backup bearing dislocation. Therefore, a direct probe into the nonlinear magnetic force model in an active magnetic bearing system is necessary. To analyze the nonlinear magnetic force model of a magnetic bearing system, phase plot analysis which is to plot the numerical solution of the nonlinear equation in several initial points in the interested region is applied. Phase plot analysis is used to observe a nonlinear dynamic system qualitatively (not quantitatively). With this method, we can get much useful information of the nonlinear system. Among this information, a bifurcation graph that represents stability and locations of fixed points is essential. From the bifurcation graph, a stability criterion of magnetic bearing system is derived.

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Stress Analysis of Linear Elastic Solid Problems by using Enhanced Meshfree Method based on Fast Derivatives Approximation (고속 도함수 근사화에 의해 개선된 무요소법을 이용한 선형탄성 고체문제의 응력해석)

  • 이상호;김효진;윤영철
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2002.10a
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    • pp.583-590
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    • 2002
  • Point collocation method based on the fast derivatives approximation of meshfree shape function is applied to solid mechanics in this study. Enhanced meshfree approximation with approximated derivative of shape function is reviewed, and formulation of linear elastic solid mechanics by point collocation method is presented. It implies that governing equation of solid mechanics with strong form is directly formulated without no numerical integration cells or grid. The regularity of weight function is not required due to a use of approximated derivative, so we propose the exponential type weight function that is discontinuous in first derivative. The convergence and stability of the proposed method is verified by passing the generalized patch test. Also, the efficiency and applicability of the proposed method in solid mechanics is verified by solving types of solid problems. Numerical results show that not only a use of proposed weight function leads lower error and higher convergence rate than that of the conventional weight functions, but also the improved collocation method with derivative approximation enables to compute the derivatives of shape function very fast and accurately enough to replace the classical direct derivative calculation.

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