• 제어로봇시스템학회논문지
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• 제6권1호
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• pp.51-56
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• 2000

This paper presents the characteristics of the dynamic response and calibration technique on a linear variable differential transformer(LVDT). The linear error of the LVDT was proven $\pm$1% in the static calibration and $\pm$0.5% in the dynamic calibration. In this paper, the linearity error generated in the static and dynamic state of the core movement can be eliminated using the correction algorithem of the static and dynamic state derived from the least square linear approximation for the nonlinearity of the curves of direct data fitting and Lagrange polynomials. With the static and dynamic calibration method, the calibration accuracy of the LVDT can be reduced to within $\pm{0.5%.}$.

• Computers and Concrete
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• 제15권4호
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• pp.673-686
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• 2015

R-curve based on the size effect law previously developed for geometrically similar specimens (geometry type III) is extended to geometries with variable depth (geometry type I) as well as with variable notch (geometry type II), where the R-curve is defined as the envelope of the family of critical strain energy release rates from specimens of different sizes. The results show that the extended R-curve for type I tends to be the same for different specimen configurations, while it is greatly dependent on specimen geometry in terms of the initial crack length. Furthermore, the predicted load-deflection responses from the suggested R-curve are found to agree well with the testing results on concrete and rock materials. Besides, maximum loads for type II specimen are predicted well from the extended R-curve.

• Membrane and Water Treatment
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• 제3권2호
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• pp.77-98
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• 2012

A two-dimensional (2D) steady state numerical model of concentration polarisation (CP) phenomena in a membrane channel has been developed using the commercially available computational fluid dynamics (CFD) package CFX (Ansys, Inc., USA). The model incorporates the transmembrane pressure (TMP), axially variable permeate flux, variable diffusivity and viscosity, and osmotic pressure effects. The model has been verified against several benchmark analytical and empirical solutions from the membrane literature. Additionally, the model is able to predict the rejection of an arbitrary solute by the membrane using a pore model, given some basic knowledge of the geometry of the solute molecule or particle, and the membrane pore geometry. This allows for predictive design of membrane systems without experimental determination of the membrane rejection for the specified operating conditions. A demonstration of the model is presented against experimental results for two uncharged test compounds (sucrose and PEG1000) from the literature. The model will be extended to incorporate charge effects, transient simulations, three-dimensional (3D) geometry and turbulent effects in future work.

• KSBB Journal
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• 제8권3호
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• pp.272-281
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• 1993

유당을 탄소원으로 K. marxianus를 발효하는 경우, 용해산소의 농도와 조엽조건에 따른 발효의 진행 상태를 정확히 예측하였다. 예측에 필요한 고정된 계수를 갖는 양론식의 수를 singular variable decomposition 분석에 의하여 결정하고 발효의 추정에 사용될 수 었는 양론관계를 target test에 의하여 결정하였으며, 발효의 진행상태를 추정하였다 또한, 단세포 단백질을 유당으로부터 연속생산하는 경우 에너지원을 효율적으로 이용하기 위한 조업조건을 제시하였다.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권8호
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• pp.545-550
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• 2004

This paper is proposed a fuzzy neural network controller based on the vector controlled induction motor drive system. The hybrid combination of fuzzy control and neural network will produce a powerful representation flexibility and numerical processing capability. Also, this paper is proposed estimation and control of speed of induction motor using ANN Controller. The back propagation neural network technique is used to provide a real time adaptive estimation of the motor speed. The error between the desired state variable and the actual one is back-propagated to adjust the rotor speed, so that the actual state variable will coincide with the desired one. The back propagation mechanism is easy to derive and the estimated speed tracks precisely the actual motor speed. This paper is proposed the theoretical analysis as well as the simulation results to verify the effectiveness of the new method.

• 전기의세계
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• 제28권1호
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• pp.59-66
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• 1979

The linearized models on per for mance dynamics of the pulse motor have been already proposed by many others. These models exhibit certain advantages of their own because of their simple formulation, but in many cases the models are proved to be inadequate for further accurate analysis of the motor dynamics, owing to impractical and rather rough assumptions in the derivation. In this study a dynamic state transition model is induced, using the equivalent circuit obtained from the operating principle of the variable reluctance pulse motor which turns out to be nonlinear equation. This nonlinear dynamic state equation is numerically analysed by the use of UNIVAC System/3(OS/3) digital computer at hand. In the course of the dynamic analysis of the performance characteristics of a testing motor, dependance of the inertia of rotor and load, the coefficient of viscous friction between rotor and housing, and the winding resistance of the stator is discussed and a comparative study of the machine constants is carried on as related to the design problem of the motor.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.110-115
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• 2001

The spherical CVT, intended to overcome some of the limitations of existing CVT designs, is marked by its simple kinematic design, improved efficiency of the shift actuator, and IVT characteristics, i.e., the ability of smooth transition between the forward, neutral, and reverse states without the need for any brakes or clutches. And it has been promised much possibility of energy savings and various applications for small power capacity machinery. Due to the nonlinearity of the spherical CVT shifting dynamics, however the original open-loop system is inherently unstable. Hence a feedback controller is necessary to make the system stable and to achieve effective tracking performance. To do this, we designed a feedback controller that cancels nonlinearities and transforms the original nonlinear system dynamics into a stable and controllable linear one, based on the input-state linearization method.

• Communications for Statistical Applications and Methods
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• 제31권1호
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• pp.143-154
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• 2024

This paper considers a combined model of exponential smoothing (ETS) and autoregressive integrated moving average (ARIMA) models that are commonly used to forecast time series data. The combined model is constructed through an innovational state space model based on the level variable instead of the differenced variable, and the identifiability of the model is investigated. We consider the maximum likelihood estimation for the model parameters and suggest the model selection steps. The forecasting performance of the model is evaluated by two real time series data. We consider the three competing models; ETS, ARIMA and the trigonometric Box-Cox autoregressive and moving average trend seasonal (TBATS) models, and compare and evaluate their root mean squared errors and mean absolute percentage errors for accuracy. The results show that the combined model outperforms the competing models.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 추계학술대회 논문집 학회본부
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• pp.352-356
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• 1990

In this paper proposed a new analysis method that can be controlled DC separately excited motor using DC chopper. An analysis method can be broadly divided the state variables method and the state space averaging method. The state variable method is largely used for analysis method in the time area, but it is complicated analysis of the nonlinear circuit and modeling of the system. Therefore a boundary of the current continuous mode and discontinuous mode can be definited by the state space averaging method. Also this paper proposed a new approximation analysis method using state space averaging method in the discontinuous mode.

• Journal of Communications and Networks
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• 제8권2호
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• pp.220-227
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• 2006

In this paper, we present a novel approach to analyze the throughput of direct-sequence spread spectrum multiple access (DS/SSMA) unslotted ALOHA system. In the unslotted system, the departure rate of interfering transmissions is proportional to the number of current interferers that can be regarded as the system state. In order to model this state-dependency, we introduce a two-dimensional state transition model that describes the state transition of the system. This model provides a more rigorous analysis tool for the DS/SSMA unslotted ALOHA systems with both fixed and variable packet lengths. Numerical results reveal that this analysis yields an accurate system performance that coincides with the simulation results. Throughout the analysis we have discovered that the state-dependency of the departure rate causes interference averaging effect in the unslotted system and that this effect yields a higher throughput for the unslotted system than for the slotted system when supported by a strong channel coding.