• 제목/요약/키워드: model.

검색결과 159,788건 처리시간 0.115초

THE DEVELOPMENT OF A ZERO-INFLATED RASCH MODEL

  • Kim, Sungyeun;Lee, Guemin
    • 한국수학교육학회지시리즈B:순수및응용수학
    • /
    • 제20권1호
    • /
    • pp.59-70
    • /
    • 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.

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

  • 권오병;이건창
    • 한국경영과학회지
    • /
    • 제23권2호
    • /
    • pp.103-129
    • /
    • 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.

  • PDF

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

  • 양승용;권태수;최원목
    • 한국철도학회논문집
    • /
    • 제11권3호
    • /
    • pp.280-285
    • /
    • 2008
  • Gurson model과 shear failure model 두 가지 파괴모델을 이용하여 노치인장시험과 초기 균열을 가지는 파쇄튜브의 압축거동을 유한요소법으로 해석하였다. Shear failure model의 파라미터 값은 노치인장시편의 시험 및 해석을 통하여 결정하였다. 항복강도와 파괴전단변형률 등의 파라미터 값을 정한 후, Gurson model과 shear failure model을 파쇄튜브의 해석에 적용하였다. Gurson model과 shear failure model이 인장시편에 대하여는 비슷한 파괴 거동을 보여주지만 파쇄튜브의 압축력과 균열 성장 속도에서는 다른 결과를 보임을 확인하였다. 즉, shear failure model에서는 Gurson model에 비하여 균열이 전파되기 위해 더 큰 압축력이 요구되었다. 이러한 현상은 shear failure model 이 재질의 손상 과정에 대한 고려를 포함하고 있지 않기 때문인 것으로 생각된다. 어느 모델이 튜브의 해석에 적당한 지를 실험을 통하여 검증할 필요가 있다.

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

  • 이영화
    • 한국환경과학회지
    • /
    • 제3권4호
    • /
    • pp.349-356
    • /
    • 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.

  • PDF

대학도서관의 복본수 결정기법에 관한 연구

  • 양재한
    • 한국도서관정보학회지
    • /
    • 제13권
    • /
    • pp.131-166
    • /
    • 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.

  • PDF

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

  • Jee, Man-Won
    • 한국국방경영분석학회지
    • /
    • 제8권1호
    • /
    • pp.71-76
    • /
    • 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.

  • PDF

차량 모델의 복잡성이 차량동력학 해석에 미치는 영향 : 모델의 비교 및 검증 (An Effect of the Complexity in Vehicle Dynamic Models on the Analysis of Vehicle Dynamic Behaviors: Model Comparison and Validation)

  • 배상우;윤중락;이장무;탁태오
    • 한국자동차공학회논문집
    • /
    • 제8권6호
    • /
    • pp.267-278
    • /
    • 2000
  • Vehicle dynamic models in handing and stability analysis are divided into three groups: bicycle model, roll axis model and full vehicle model. Bicycle model is a simple linear model, which hag two wheels with load transfer being ignored. Roll axis model treats left and right wheels independently. In this model, load transfer has a great effect on nonlinearity of tire model. Effects of suspension system can be analyzed by using full vehicle model, which is included suspension stroke motions. In this paper, these models are validated and compared through comparison with road test, and the effects of suspension kinematics and compliance characteristics on vehicle motion are analyzed. In handling and stability analysis, roll axis model can simulate the real vehicle motion more accurately than full vehicle model. Compliance steer has a significant effect, but the effect of suspension kinematics is negligible.

  • PDF

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

  • 조수길;변현석;이태희
    • 대한기계학회논문집A
    • /
    • 제33권8호
    • /
    • pp.813-818
    • /
    • 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.

Modelling the reinforced concrete beams strengthened with GFRP against shear crack

  • Kaya, Mustafa;Yaman, Canberk
    • Computers and Concrete
    • /
    • 제21권2호
    • /
    • pp.127-137
    • /
    • 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.

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

  • 송근원;강대창
    • 보건행정학회지
    • /
    • 제13권1호
    • /
    • pp.69-97
    • /
    • 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.