• 제목/요약/키워드: Multi-Level Modeling

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A Development of Inflow Forecasting Models for Multi-Purpose Reservior (다목적 저수지 유입량의 예측모형)

  • Sim, Sun-Bo;Kim, Man-Sik;Han, Jae-Seok
    • Proceedings of the Korea Water Resources Association Conference
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    • 1992.07a
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    • pp.411-418
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    • 1992
  • The purpose of this study is to develop dynamic-stochastic models that can forecast the inflow into reservoir during low/drought periods and flood periods. For the formulation of the models, the discrete transfer function is utilized to construct the deterministic characteristics, and the ARIMA model is utilized to construct the stochastic characteristics of residuals. The stochastic variations and structures of time series on hydrological data are examined by employing the auto/cross covariance function and auto/cross correlation function. Also, general modeling processes and forecasting method are used the model building methods of Box and Jenkins. For the verifications and applications of the developed models, the Chungju multi-purpose reservoir which is located in the South Han river systems is selected. Input data required are the current and past reservoir inflow and Yungchun water levels. In order to transform the water level at Yungchon into streamflows, the water level-streamflows rating curves at low/drought periods and flood periods are estimated. The models are calibrated with the flood periods of 1988 and 1989 and hourly data for 1990 flood are analyzed. Also, for the low/drought periods, daily data of 1988 and 1989 are calibrated, and daily data for 1989 are analyzed.

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An Integrated Approach to Linking Job Love with Contextual Factors and Performance: An Empirical Study from Pakistan

  • BIBI, Naila;SAEED, Bilal Bin;AFRIDI, Muhammad Asim
    • The Journal of Asian Finance, Economics and Business
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    • v.9 no.5
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    • pp.157-169
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    • 2022
  • Job love is an emerging phenomenon, which is the utmost approach to fulfilling employees' and organizations' mutual interests, especially performance. The current study aims to define and extend the existing proposed construct of "loving one's job" as job love. It provides a novel theoretical multi-level framework of job love, contextual factors, and performance principled on the attraction-selection-attrition framework and social exchange theory through an integrated approach. This study collected cross-sectional data through a questionnaire from 332 nurses across eight tertiary hospitals in Khyber Pakhtunkhwa, Pakistan. The findings are based on the structural equation modeling technique (SEM) at multi-levels. The results show significant relationships between job love, contextual factors, and performance at the individual and organization levels. There are some insignificant relationships between the variables at the cross-level. Job love plays a key role for both employees and organizations. It facilitates the individuals in the recruitment process to select the job they love, be a good fit, and stay committed to that particular job and organization. This phenomenon allows people to pursue their common interests. Job love assists firms in developing human resource capacity utilization plans that satisfy the needed requirements.

Modeling and Simulation of Platform Specific Model in MPSoC Environment (MPSoC용 임베디드 소프트웨어의 PSM 모델링 및 시뮬레이션)

  • Song, In-Gwon;Oh, Gi-Young;Hong, Jang-Eui;Bae, Doo-Hwan
    • Journal of KIISE:Software and Applications
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    • v.34 no.8
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    • pp.697-707
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    • 2007
  • Since embedded software is very dependent for target hardware architecture, characteristics of the platform must be considered when designing the software. Furthermore, MPSoCs consists of heterogeneous hardware components that are specified in micro level. Thus mapping of embedded software for MPSoCs should be considered the characteristics. In this paper, we provide an approach to automatic mapping PIM (Platform Independent Model) of an embedded software to PSM(Platform Specific Model) for MPSoC(Multi Processor System On Chip) and verify its effectiveness with simulation. In the proposed approach, tasks are derived from an object oriented model based on the UML (Unified Modeling Language). And then the types of the derived tasks are identified. With the identified types and inter relationship between tasks, the tasks are assigned to appropriate heterogeneous hardware components. We expect that the approach improve accuracy of the assigning and concurrency of the deployed software.

Ecological Correlates of Cardiovascular Disease Risk in Korean Blue-collar Workers: A Multi-level Study (다수준 분석을 이용한 한국 생산직 근로자의 심혈관질환 위험에 대한 생태학적 요인)

  • Hwang, Won Ju;Park, Yunhee
    • Journal of Korean Academy of Nursing
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    • v.45 no.6
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    • pp.857-867
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    • 2015
  • Purpose: The purpose of this study was to investigate individual and organizational level of cardiovascular disease (CVD) risk factors associated with CVD risk in Korean blue-collar workers working in small sized companies. Methods: Self-report questionnaires and blood sampling for lipid and glucose were collected from 492 workers in 31 small sized companies in Korea. Multilevel modeling was conducted to estimate effects of related factors at the individual and organizational level. Results: Multilevel regression analysis showed that workers in the workplace having a cafeteria had 1.81 times higher CVD risk after adjusting for factors at the individual level (p =.022). The explanatory power of variables related to organizational level variances in CVD risk was 17.1%. Conclusion: The results of this study indicate that differences in the CVD risk were related to organizational factors. It is necessary to consider not only individual factors but also organizational factors when planning a CVD risk reduction program. The factors caused by having cafeteria in the workplace can be reduced by improvement in the CVD-related risk environment, therefore an organizational-level intervention approach should be available to reduce CVD risk of workers in small sized companies in Korea.

Constitutive Equations Based on Cell Modeling Method for 3D Circular Braided Glass Fiber Reinforced Composites

  • Lee, Wonoh;Kim, Ji Hoon;Shin, Heon-Jung;Chung, Kwansoo;Kang, Tae Jin;Youn, Jae Ryoun
    • Fibers and Polymers
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    • v.4 no.2
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    • pp.77-83
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    • 2003
  • The cell modeling homogenization method to derive the constitutive equation considering the microstructures of the fiber reinforced composites has been previously developed for composites with simple microstructures such as 2D plane composites and 3D rectangular shaped composites. Here, the method has been further extended for 3D circular braided com-posites, utilizing B-spline curves to properly describe the more complex geometry of 3D braided composites. For verification purposes, the method has been applied for orthotropic elastic properties of the 3D circular braided glass fiber reinforced com-posite, in particular for the tensile property. Prepregs of the specimen have been fabricated using the 3D braiding machine through RTM (resin transfer molding) with epoxy as a matrix. Experimentally measured uniaxial tensile properties agreed well with predicted values obtained for two volume fractions.

A Study on the modeling and operation control of a variable speed synchronous wind power system (가변속 동기형 풍력발전 시스템 모델링 및 운전제어에 대한 연구)

  • Huh, Hyun;Lee, Jaehak
    • The Journal of the Korea institute of electronic communication sciences
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    • v.10 no.8
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    • pp.935-944
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    • 2015
  • This study performs the dynamic modeling and the simulation of variable speed wind power system and implements the models of wind speed, wind turbine & PMSG, and MPPT & pitch control as well. The simulation of wind turbine was performed by using the power coefficient and other simulation parameters which were extracted with reference to the commercial 5MW class wind turbine data. As the result of this simulation, MPPT control is confirmed, maintaining the maximum power coefficient as far as the rated speed 12[m/s]. Over 12[m/s] wind speed, this wind power system makes it possible to keep the stable output by controlling the pitch angle.

Optimum design of steel frame structures considering construction cost and seismic damage

  • Kaveh, A.;Fahimi-Farzam, M.;Kalateh-Ahani, M.
    • Smart Structures and Systems
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    • v.16 no.1
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    • pp.1-26
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    • 2015
  • Minimizing construction cost and reducing seismic damage are two conflicting objectives in the design of any new structure. In the present work, we try to develop a framework in order to solve the optimum performance-based design problem considering the construction cost and the seismic damage of steel moment-frame structures. The Park-Ang damage index is selected as the seismic damage measure because it is one of the most realistic measures of structural damage. The non-dominated sorting genetic algorithm (NSGA-II) is employed as the optimization algorithm to search the Pareto optimal solutions. To improve the time efficiency of the proposed framework, three simplifying strategies are adopted: first, simplified nonlinear modeling investigating minimum level of structural modeling sophistication; second, fitness approximation decreasing the number of fitness function evaluations; third, wavelet decomposition of earthquake record decreasing the number of acceleration points involved in time-history loading. The constraints of the optimization problem are considered in accordance with Federal Emergency Management Agency's (FEMA) recommended seismic design specifications. The results from numerical application of the proposed framework demonstrate the efficiency of the framework in solving the present multi-objective optimization problem.

Predictive control and modeling of a point absorber wave energy harvesting connected to the grid using a LPMSG-based power converter

  • Abderrahmane Berkani;Mofareh Hassan Ghazwani;Karim Negadi;Lazreg Hadji;Ali Alnujaie;Hassan Ali Ghazwani
    • Ocean Systems Engineering
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    • v.14 no.1
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    • pp.17-52
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    • 2024
  • In this paper, the authors explore the modeling and control of a point absorber wave energy converter, which is connected to the electric grid via a power converter that is based on a linear permanent magnet synchronous generator (LPMSG). The device utilizes a buoyant mechanism to convert the energy of ocean waves into electrical power, and the LPMSG-based power converter is utilized to change the variable frequency and voltage output from the wave energy converter to a fixed frequency and voltage suitable for the electric grid. The article concentrates on the creation of a predictive control system that regulates the speed, voltage, and current of the LPMSG, and the modeling of the system to simulate its behavior and optimize its design. The predictive model control is created to guarantee maximum energy output and stable grid connection, using Matlab Simulink to validate the proposed strategy, including control side generator and predictive current grid-side converter loops.

The Mediating Effect of Strengths Use on the Relation of Strengths Knowledge and Career Decision Level among College Students: Multi-Group Analysis based on Goal Orientation Type (대학생의 강점인식과 진로결정수준의 관계에서 강점활용의 매개효과 검증: 목표지향성 유형에 따른 다집단 분석)

  • Kim, Min-Jung;Lee, Hee-Kyung
    • The Journal of the Korea Contents Association
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    • v.17 no.12
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    • pp.600-616
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    • 2017
  • This study examined the mediating effects of strengths use on the relation of strengths knowledge and career decision level among 393 college students. To analyze the data, the structural equation modeling were used. Finally, the mediating model examined the differences between goal orientation(validation-seeking orientation, growth-seeking orientation) of Dykman by carrying out of multi-group analysis. The results were as followed. First, strengths use partially mediated the relationship between strengths knowledge and career decision level. Second, the mediating model showed variation in different goal orientation type group. In other words, strengths knowledge occurs more severely and distinctively impact on career decision level in growth-seeking group than validation-seeking group. Based on the findings, implications for counseling practice, limitations of this study and recommendations for future study were discussed.

Feasibility Study of Hierarchical Kriging Model in the Design Optimization Process (계층적 크리깅 모델을 이용한 설계 최적화 기법의 유용성 검증)

  • Ha, Honggeun;Oh, Sejong;Yee, Kwanjung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.42 no.2
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    • pp.108-118
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    • 2014
  • On the optimization design problem using surrogate model, it requires considerable number of sampling points to construct a surrogate model which retains the accuracy. As an alternative to reduce construction cost of the surrogate model, Variable-Fidelity Modeling(VFM) technique, where correct high fidelity model based on the low fidelity surrogate model is introduced. In this study, hierarchical kriging model for variable-fidelity surrogate modeling is used and an optimization framework with multi-objective genetic algorithm(MOGA) is presented. To prove the feasibility of this framework, airfoil design optimization process is performed for the transonic region. The parameters of PARSEC are used to design variables and the optimization process is performed in case of varying number of grid and varying fidelity. The results showed that pareto front of all variable-fidelity models are similar with its single-level of fidelity model and calculation time is considerably reduced. Based on computational results, it is shown that VFM is a more efficient way and has an accuracy as high as that single-level of fidelity model optimization.