• Title/Summary/Keyword: Continuous-Time Model

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Bootstrap Confidence Intervals for the INAR(p) Process

  • Kim, Hee-Young;Park, You-Sung
    • Communications for Statistical Applications and Methods
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    • v.13 no.2
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    • pp.343-358
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    • 2006
  • The distributional properties of forecasts in an integer-valued time series model have not been discovered yet mainly because of the complexity arising from the binomial thinning operator. We propose two bootstrap methods to obtain nonparametric prediction intervals for an integer-valued autoregressive model : one accommodates the variation of estimating parameters and the other does not. Contrary to the results of the continuous ARMA model, we show that the latter is better than the former in forecasting the future values of the integer-valued autoregressive model.

Experimentally Evaluation of a Liquid Pool Spreading Model with Continuous Release (연속누출을 가지는 액체 풀 확산 모델의 실험적 평가)

  • KIM, TAEHOON;DO, KYU HYUNG;KIM, MYUNGBAE;HAN, YONG-SHIK;CHOI, BYUNG-IL
    • Transactions of the Korean hydrogen and new energy society
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    • v.26 no.6
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    • pp.659-665
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    • 2015
  • In this study, an experimental investigation is performed for evaluation of a liquid pool spreading model with continuous release. The model considered in this study was developed based on a concept which means that the liquid pool spreading is governed by a balance between an inertia force from gravity and a frictional force from friction with the ground under the whole base of the liquid pool. For evaluation of the model, experimental study is performed. Experimental apparatus is setup for measuring release rate, spreading velocity, and evaporation rate from a liquid pool. The experimental results are compared with results from the model. By applying release and evaporation rates obtained from experiments to solving the model, liquid pool radius variation according to time can be obtained. For evaluation of an effect of friction force in the spreading model, results obtained from the models with and without the friction force are compared with those obtained from the experiments. As a result, it is shown that there exists a large deviation between the results obtained from the model without the friction force and the experimental results. On the other hand, the tendency of liquid pool radius variation according to time is similar between the results obtained from the model without the friction force and the experimental results.

A Study on Simulation of Desulfurization in a Continuous Fluidized Bed Using Natural Manganese Ore (천연망간광석을 이용한 연속식 유동층 반응기에서 탈황모사에 관한 연구)

  • Hong, Sung Chang
    • Korean Chemical Engineering Research
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    • v.43 no.2
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    • pp.278-285
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    • 2005
  • In the present work, a reaction of sulfur removal and simulation of desulfurization based on the grain model and two-phase theory were studied using natural manganese ore (NMO) as a sorbent in a continuous fluidized bed reactor. The effect of desulfurization was investigated through the grain model considered the change of pore structure as a function of desulfurization time, particle size of NMO, and diffusion velocity of $SO_2$ in the pores. Among these parameters, the diffusion of $SO_2$ in the pores of NMO was the most important factor. Moreover, the reaction of sulfur removal and desulfurization in a continuous fluidized bed reactor using NMO as a sorbent could be well predict through the grain model and two-phase theory, respectively.

On the Fuzzy Control of Nonlinear Dynamic Systems with Inaccessible States

  • Kim, Kwangtae;Joongseon Joh;Woohyen Kwon
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 1998.06a
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    • pp.331-336
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    • 1998
  • A systematic design method for PDC(Parallel Distributed Compensation)-type continuous time Takagi-Sugeno(T-S in short) fuzzy control systems which have inaccessible states is developed in this paper. Reduced-dimensional fuzzy state estimator is introduced from existing T-S fuzzy model using the PDC structure of Wang et al. [1] LMI(Linear Matrix Inequalities) problems which represent the stabililty of the reduced-dimensional fuzzy state estimator are derived. Pole placement constraints idea for each rules is adopted to determine the estimator gains and they are also revealed as LMI problems. these LMI problems are combined with Joh et al's [7][8] LMI problems for PDC -type continuous time T-S fuzzy controller design to yield a systematic design method for PDC -type continuous time T-S fuzzy control systems which have inaccessible states.

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A Study on the Design Method of a Continuous Time Deadbeat Controller (연속시간 유한정정제어기의 설계방법 고찰)

  • 김성열;이금원
    • 제어로봇시스템학회:학술대회논문집
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    • 2000.10a
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    • pp.326-326
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    • 2000
  • Continuous time system deadbeat controller(CdbC) has been studied mainly since 1992 especially by Japan researchers. They suggested delay elements. These elements stem from the finite Laplace Transform which is the starting point in deadbeat control system design in continuous time system. Every transfer function is established by these elements. From some conditions such as internal model stability and peasibility of a CdbC controller. unknown polynomials or coefficients can be calculated. In this paper, optimal pole placement of the closed loop system is suggested. From this. a CdbC controller with lower order can be obtained which attains the same level of weighted sensitivity function's H$_{\infty}$ norm used as a measure of the robustness property as existing CdbCs.

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Development of Multiple Transient Storage Model Using Particle Tracking Method (입자추적방법을 이용한 다중저장대모형 개발)

  • Cheong, Tae-Sung;Seo, Il-Won
    • Journal of Korea Water Resources Association
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    • v.37 no.4
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    • pp.257-271
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    • 2004
  • To evaluate behavior in representing solute transport in natural streams, the storage zone model of the axially periodic transient storage zones is developed. The periodic transient storage zone model and continuous storage zone model are verified using the parameters and the tracer concentration vs. time curves observed in laboratory channels. The periodic storage zone model best fit the measured concentration vs. time curves, while the continuous storage model fails to describe some fluctuations and the plateau region of the tail occurring in a discontinuous transient storage system. Dispersion data from Shingobee River, Minnesota, U. S. A. show that the concentration curves simulated by the proposed model fit the observed concentration curves well.

A Statistical Model for Severe Acute Respiratory Syndrome

  • Hong, Yeon-Woong
    • Journal of the Korean Data and Information Science Society
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    • v.14 no.3
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    • pp.615-622
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    • 2003
  • The severe acute respiratory syndrome(SARS) is a novel infectious disease with global impact. The rapid worldwide spread of SARS has led to 30 countries reporting cases of July 13, 2003. In this paper, we develop a statistical model for SARS-caused-death data under some assumptions. The model developed is a continuous time Markov process with a constant intensity for each stage.

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Intelligent Digital Redesign of Uncertain Nonlinear Systems : Global approach (불확실성이 포함된 비선형 시스템에 대한 전역적 접근의 지능형 디지털 재설계)

  • Sung Hwachang;Joo Younghoon;Park Jinbae;kim Dowan
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 2005.11a
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    • pp.95-98
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    • 2005
  • This paper presents intelligent digital redesign method of global approach for hybrid state space fuzzy-model-based controllers. For effectiveness and stabilization of continuous-time uncertain nonlinear systems under discrete-time controller, Takagi-Sugeno(TS) fuzzy model is used to represent the complex system. And global approach design problems viewed as a convex optimization problem that we minimize the error of the norm bounds between nonlinearly interpolated linear operators to be matched. Also by using the power series, we analyzed nonlinear system's uncertain parts more precisely. When a sampling period is sufficiently small, the conversion of a continuous-time structured uncertain nonlinear system to an equivalent discrete -time system have proper reason. Sufficiently conditions for the global state -matching of the digitally controlled system are formulated in terms of linear matrix inequalities (LMls). Finally, we prove the effectiveness and stabilization of the proposed intelligent digital redesign method by applying the chaotic Lorentz system.

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Model Indentification and Discrete-Time Sliding Mode Control of Electro-Hydraulic Systems (전기-유압 서보 시스템의 모델규명 및 이산시간 슬라이딩 모드 제어)

  • 엄상오;황이철;박영산
    • Journal of Advanced Marine Engineering and Technology
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    • v.24 no.1
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    • pp.94-103
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    • 2000
  • This paper describes the model identification and the discrete-time sliding mode control of electro-hydraulic servo systems which are composed of servo valves, double-rod cylinder and load mass. The controlled plant is identified as a 3th-order discrete-time ARMAX model obtained from the prediction error algorithm, where a nominal model and modeling errors are zuantitatively constructed. The discrete sliding mode controller for 3th-order ARMAX model is designed in discrete-time domain, where all states are observed from Kalman filter. The discrete sliding mode controller has better tracking performance than that obtained from continuous-time sliding mode controller, in experiment.

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A Study on Microblog Service Continuous Use Intention: Focusing on Influence (마이크로블로그 서비스의 지속사용의도에 관한 연구)

  • Kim, Gyung-Jun;Lee, Ho;Son, Soo-Min
    • The Journal of Information Systems
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    • v.23 no.1
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    • pp.73-91
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    • 2014
  • Microblog is emerging as a new communication service because of its usefulness and real-time accessability. Recently, microblog services, such as twitter and me2day in Korea, are getting a great attention. Continuous use intention is critical to sustain the service. However, most recent studies are based on Technology Acceptance Model(TAM) and Expectation Confirmation Model(ECM). These models are only focused on individual factors and overlook social influence factors. Social influence has been indicated as a critical factor of technology adoption and diffusion in social context(Davis, 1989; Fulk et al., 1987). In this study, we explore factors related to social influence which effect on continuous use intention for 'me2day' that is one of the most famous microblog in Korea. The purpose of this study is to understand continuous use intention and examine the relationship among social influence factors, social presence, and continuous use intention. To understand the phenomenon of continuous use intention in microblog service, this study employed social influence theory and expanded it by adding personal network exposure and group norm as additional social influence factors. The results show that social identity, group norms, and social presence positively influences continuous use intention. Contrary to our expectation, personal network exposure does not influence on continuous use intention. Academically, this research can contribute to microblog research field through elucidating the relationship among social influence factors, social presence, and continuous use intention. Although there is not enough research which is considered social influence factors as major explanation for continuous use intention, this study can give novel point of view to understand continuous use intention of microblog. Practically, service providers could consider ways to encourage users to continually use microblog service by reinforcing social influence factors and social presence.