• Title, Summary, Keyword: Model

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THE DEVELOPMENT OF A ZERO-INFLATED RASCH MODEL

  • Kim, Sungyeun;Lee, Guemin
    • The Pure and Applied Mathematics
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    • v.20 no.1
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    • pp.59-70
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    • 2013
  • The purpose of this study was to develop a zero-inflated Rasch (ZI-Rasch) model, a combination of the Rasch model and the ZIP model. The ZI-Rasch model was considered in this study as an appropriate alternative to the Rasch model for zero-inflated data. To investigate the relative appropriateness of the ZI-Rasch model, several analyses were conducted using PROC NLMIXED procedures in SAS under various simulation conditions. Sets of criteria for model evaluations (-2LL, AIC, AICC, and BIC) and parameter estimations (RMSE, and $r$) from the ZI-Rasch model were compared with those from the Rasch model. In the data-model fit indices, regardless of the simulation conditions, the ZI-Rasch model produced better fit statistics than did the Rasch model, even when the response data were generated from the Rasch model. In terms of item parameter ${\lambda}$ estimations, the ZI-Rasch model produced estimates similar to those of the Rasch model.

A Multilevel Model Integration for Collaborative Decision Making (협동적 의사결정을 위한 다단계 모형 통합)

  • 권오병;이건창
    • Journal of the Korean Operations Research and Management Science Society
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    • v.23 no.2
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    • pp.103-129
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    • 1998
  • Corporate level decision making with multiple decision makers in a consistent way is essential in Decision Support System. However, since the decision makers have different interests and knowledge, the models used by them are also different in their level of abstraction. This makes decision makers waste a lot of efforts for an integrated decision making. The purpose of this paper is to propose an integration mechanism so that collaborative decision making models may be used synthetically in multi-abstraction level. Models are classified as multimedia model, mathematical model, qualitative model, causal & directional model, causal model, directional model and relationship model according to the level of abstraction. The proposed integration mechanism consists of model interpretation phase. model transformation phase, and model integration phase. Specifically, the model transformation Phase is divided into (1) model tightening mode which gather information to make a model transformed into upper level model, and (2) model relaxing mode which makes lower level model. In the model integration phase, models of same level are to be integrated schematically. An illustrative M&A-decision example is given to show the possibility of the methodology.

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Analyses of Fracture Tube Tearing using Gurson Model and Shear Failure Model (Gurson Model과 Shear Failure Model을 이용한 파쇄튜브의 찢어짐 해석)

  • Yang, Seung-Yong;Kwon, Tae-Su;Choi, Won-Mok
    • Journal of the Korean Society for Railway
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    • v.11 no.3
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    • pp.280-285
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    • 2008
  • Two kinds of failure model, that is, the Gurson model and a shear failure model were used for the finite element analyses of simple and notch tensile specimens and axial compression of a fracture tube with initial saw-cuts. The parameter values for the shear failure model were determined by a combined experimental and numerical analysis of the notch tensile specimens. After fitting the numerical parameters such as the yielding stress and the fracture shear strains, the Gurson model and the shear failure model were applied to the analysis of the fracture tube. Although the Gurson model and the shear failure model showed similar fracture behavior for the case of the tensile specimens, the respective results were different in the axial force and the crack growth rate of the fracture tube. That is, the shear failure model required more axial force to make the cracks propagate along the tube than the Gurson model. These are believed to show the lack of damage evolution process of the shear failure model. To decide which model is better in the tube analysis, experimental verification will be necessary.

A Linear Reservoir Model with Kslman Filter in River Basin (Kalman Filter 이론에 의한 하천유역의 선형저수지 모델)

  • 이영화
    • Journal of Environmental Science International
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    • v.3 no.4
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    • pp.349-356
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    • 1994
  • The purpose of this study is to develop a linear reservoir model with Kalman filter using Kalman filter theory which removes a physical uncertainty of :ainfall-runoff process. A linear reservoir model, which is the basic model of Kalman filter, is used to calculate runoff from rainfall in river basin. A linear reservoir model with Kalman filter is composed of a state-space model using a system model and a observation model. The state-vector of system model in linear. The average value of the ordinate of IUH for a linear reservoir model with Kalman filter is used as the initial value of state-vector. A .linear reservoir model with Kalman filter shows better results than those by linear reserevoir model, and decreases a physical uncertainty of rainfall-runoff process in river basin.

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대학도서관의 복본수 결정기법에 관한 연구

  • 양재한
    • Journal of Korean Library and Information Science Society
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    • v.13
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    • pp.131-166
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    • 1986
  • This study is designed to review the methods of duplicate copies decision making in the academic library. In this thesis, I surveyed queueing & markov model, statistical model, and simulation model. The contents of the study can be summarized as follows: 1) Queueing and markov model is used for one of duplicate copies decision-making methods. This model was suggested by Leimkuler, Morse, and Chen, etc. Leimkuler proposed growth model, storage model, and availability model through using system analysis method. Queueing theory is a n.0, pplied to Leimkuler's availability model. Morse ad Chen a n.0, pplied queueing and markov model to their theory. They used queueing theory for measuring satisfaction level and Markov model for predicting user demand. 2) Another model of duplicate copies decision-making methods is statistical model. This model is suggested by Grant and Sohn, Jung Pyo. Grant suggested a model with a formula to satisfy the user demand more than 95%, Sohn, Jung Pyo suggested a model with two formulars: one for duplicate copies decision-making by using standard deviation and the other for duplicate copies predicting by using coefficient of variation. 3) Simulation model is used for one of duplicate copies decision-making methods. This model is suggested by Buckland and Arms. Buckland considered both loan period and duplicate copies simultaneously in his simulation model. Arms suggested computer-simulation model as one of duplicate copies decision-making methods. These methods can help improve the efficiency of collection development and solve some problems (space, staff, budget, etc, ) of Korean academic libraries today.

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Combining Regression Model and Time Series Model to a Set of Autocorrelated Data

  • Jee, Man-Won
    • Journal of the military operations research society of Korea
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    • v.8 no.1
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    • pp.71-76
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    • 1982
  • A procedure is established for combining a regression model and a time series model to fit to a set of autocorrelated data. This procedure is based on an iterative method to compute regression parameter estimates and time series parameter estimates simultaneously. The time series model which is discussed is basically AR(p) model, since MA(q) model or ARMA(p,q) model can be inverted to AR({$\infty$) model which can be approximated by AR(p) model. The procedure discussed in this articled is applied in general to any combination of regression model and time series model.

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Selection Method of Global Model and Correlation Coefficients for Kriging Metamodel (크리깅 메타모델의 전역모델과 상관계수 선정 방법)

  • Cho, Su-Kil;Byun, Hyun-Suk;Lee, Tae-Hee
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.8
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    • pp.813-818
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    • 2009
  • Design analysis and computer experiments (DACE) model is widely used to express efficiently nonlinear responses in the field of engineering design. As a DACE model, kriging model can approximately replace a simulation model that is very expensive or highly nonlinear. The kriging model is composed of the summation of a global model and a local model representing deviation from the global model. The local model is determined by correlation coefficient with the pre-sampled points, where the accuracy and robustness of the kriging model depends on the selection of proper correlation coefficients. Therefore, to achieve the robust kriging model, the range of the correlation coefficients is explored with respect to the degrees of the global model. Based on this study we propose the proper orders of the global model and range of parameters to make accurate and robust kriging model.

Determinants of the Community Health Service Utilization (지역 보건서비스의 산출에 영향을 미치는 요인)

  • 송근원;강대창
    • Health Policy and Management
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    • v.13 no.1
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    • pp.69-97
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    • 2003
  • This study focuses on the determinants of the community health service utilization. Theories suggest seven models for community health service utilization, which are divided largely into two groups such as Health Service Supply Model and Health Service Demand Model: Supply Model includes Medical Implements Model, Personnel and Budget Model, Management System Model, Staffs' Behavior Model, Service Quality Model; Demand Model includes Area Model and Clients' Characteristics Model. This paper tests how the above models influence on the community health service utilization. After interviewing some administrative staffs of the Community Health Service Center at Pusan, questionnaires were made and mailed to the staffs of 198 Korean Community Health Service Center as a universe, among which from 98 centers we got response. Analyzing the data from the questionnaires, we found "the number of personnels in the health service center" and "demands for medical service" as important variables to affect the utilization of the community health service center. These two variables are typical factors representing Supply Model and Demand Model each. However, the variables selected from Management System Model, Administrative Behavior Model, Service Quality Model and Area model are not significant in a statistical sense. The paper suggests that to recruit the personnels, especially nurses, and to make out the demands of the clients for health service be the precedent conditions to increase the utilization of the Community Health Service Centers in Korea.ce Centers in Korea.

Modelling the reinforced concrete beams strengthened with GFRP against shear crack

  • Kaya, Mustafa;Yaman, Canberk
    • Computers and Concrete
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    • v.21 no.2
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    • pp.127-137
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    • 2018
  • In this study, the behavior of the number of anchorage bolts on the glass-fiber reinforced polymer (GFRP) plates adhered to the surfaces of reinforcing concrete (RC) T-beams was investigated analytically. The analytical results were compared to the test results in term of shear strength, and midpoint displacement of the beam. The modelling of the beams was conducted in ABAQUS/CAE finite element software. The Concrete Damaged Plasticity (CDP) model was used for concrete material modeling, and Classical Metal Plasticity (CMP) model was used for reinforcement material modelling. Model-1 was the reference specimen with enough sufficient shear reinforcement, and Model-2 was the reference specimen having low shear reinforcement. Model-3, Model-4 and Model-5 were the specimens with lower shear reinforcement. These models consist of a single variable which was the number of anchorage bolts implemented to the GFRP plates. The anchorage bolts of 2, 3, and 4 were mutually mounted on each GFRP plates through the beam surfaces for Model-3, Model-4, and Model-5, respectively. It was found that Model-1, Model-3, Model-4 and Model-5 provided results approximately equal to the test results. The results show that the shear strength of the beams increased with increasing of anchorage numbers. While close results were obtained for Model-1, Model-3, Model-4 and Model-5, in Model-2, the rate of increase of displacement was higher than the increase of load rate. It was seen, finite element based ABAQUS program is inadequate in the modeling of the reinforced concrete specimens under shear force.

A Model Formalization Methodology of Discrete Event Simulation with Formal Tools (형식 도구를 이용한 이산사건 시뮬레이션의 모델 형식화 방법론)

  • ;;Jeong, Young Sik;Baik, Doo Kwon
    • Journal of the Korean Operations Research and Management Science Society
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    • v.17 no.3
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    • pp.79-99
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    • 1992
  • The DEVS (Discrete Event system Specification) formal model for discrete event simulation is a hierarchical, modular model. Because the DEVS formal model has a mathematical structure, it provides a theoretic background of discrete event simulation model. However, the DEVS formal model is difficult to understand because of its mathematical structure. Also, since the DEVS formal model is often constructed by heuristic, subjective method of model designer from the model, a systematic model built-in methodology does not exist. In this paper, we propose the model formalization methodology from an informal model to the DEVS formal model. For this formalization methodology, we introduce formal tools for model construction based on the DEVS ( from an informal model : Event Dependency Graph (EDG) for the event analysis and State Representation Graph(SRG) for the system state analysis.

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