• 제목/요약/키워드: Mixed-effect model

검색결과 568건 처리시간 0.029초

Implementation Strategy and Effect Analysis of MES for a Small and Medium PCB Production Company based on BPR Methodology (BPR 방법론에 기반한 중소 PCB 제조업체의 MES 구축 전략과 효과분석)

  • Kim, Gun-Yeon;Jin, Yoo-Eui;Noh, Sang-Do;Choi, Sang-Su;Jo, Yong-Ju;Choi, Seog-Ou
    • IE interfaces
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    • 제24권3호
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    • pp.231-240
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    • 2011
  • Manufacturing enterprises have been doing their best endeavors to obtain competitiveness using various methodologies, such as information technology. In order to achieve competitiveness, they are adopting manufacturing execution system (MES). MES is a total management system that manages from the beginning of the production by product order until the quality inspection of the finished product. And MES is an inter-mediator for supplementation of information gap between ERP and inspection machine and equipment. This paper describes on establishment of effective strategy based on BPR methodology and implementation of MES small and medium PCB manufacturing company with multiple-types of products and mixed process flows. And then we proposed evaluation model based on balanced score card (BSC) for considering non-finance elements as well as finance elements. With evaluation model, we analyzed benefits and effects of MES.

Dynamic response of post-tensioned rocking wall-moment frames under near-fault ground excitation

  • Feng, Ruoyu;Chen, Ying;Cui, Guozhi
    • Earthquakes and Structures
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    • 제15권3호
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    • pp.243-251
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    • 2018
  • The dynamic responses of a rocking wall-moment frame (RWMF) with a post-tensioned cable are investigated. The nonlinear equations of motions are developed, which can be categorized as a single-degree-of-freedom (SDOF) model. The model is validated through comparison of the rocking response of the rigid rocking wall (RRW) and displacement of the moment frame (MF) against that obtained from Finite Element analysis when subjected ground motion excitation. A comprehensive parametric analysis is carried out to determine the seismic performance factors of the RWMF systems under near-fault trigonometric pulse excitation. The horizontal displacement of the RWMF system is compared with that of MF structures without RRW, revealing the damping effect of the RRW. Frame displacement spectra excited by trigonometric pulses and recorded earthquake ground motions are constructed. The effects of pulse type, mass ratio, frame stiffness, and wall slenderness variations on the displacement spectra are presented. The paper shows that the coupling with a RRW has mixed results on suppressing the maximum displacement response of the frame.

Biofilm formation on denture base resin including ZnO, CaO, and TiO2 nanoparticles

  • Anwander, Melissa;Rosentritt, Martin;Schneider-Feyrer, Sibylle;Hahnel, Sebastian
    • The Journal of Advanced Prosthodontics
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    • 제9권6호
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    • pp.482-485
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    • 2017
  • PURPOSE. This laboratory study aimed to investigate the effect of doping an acrylic denture base resin material with nanoparticles of ZnO, CaO, and $TiO_2$ on biofilm formation. MATERIALS AND METHODS. Standardized specimens of a commercially available cold-curing acrylic denture base resin material were doped with 0.1, 0.2, 0.4, or 0.8 wt% commercially available ZnO, CaO, and $TiO_2$ nanopowder. Energy dispersive X-ray spectroscopy (EDX) was used to identify the availability of the nanoparticles on the surface of the modified specimens. Surface roughness was determined by employing a profilometric approach; biofilm formation was simulated using a monospecies Candida albicans biofilm model and a multispecies biofilm model including C. albicans, Actinomyces naeslundii, and Streptococcus gordonii. Relative viable biomass was determined after 20 hours and 44 hours using a MTT-based approach. RESULTS. No statistically significant disparities were identified among the various materials regarding surface roughness and relative viable biomass. CONCLUSION. The results indicate that doping denture base resin materials with commercially available ZnO, CaO, or $TiO_2$ nanopowders do not inhibit biofilm formation on their surface. Further studies might address the impact of varying particle sizes as well as increasing the fraction of nanoparticles mixed into the acrylic resin matrix.

Analytical model for estimation of digging forces and specific energy of cable shovel

  • Stavropoulou, M.;Xiroudakis, G.;Exadaktylos, G.
    • Coupled systems mechanics
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    • 제2권1호
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    • pp.23-51
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    • 2013
  • An analytical algorithm for the estimation of the resistance forces exerted on the dipper of a cable shovel and the specific energy consumed in the cutting-loading process is presented. Forces due to payload and to cutting of geomaterials under given initial conditions, cutting trajectory of the bucket, bucket's design, and geomaterial properties are analytically computed. The excavation process has been modeled by means of a kinematical shovel model, as well as of dynamic payload and cutting resistance models. For the calculation of the cutting forces, a logsandwich passive failure mechanism of the geomaterial is considered, as has been found by considering that a slip surface propagates like a mixed mode crack. Subsequently, the Upper-Bound theorem of Limit Analysis Theory is applied for the approximate calculation of the maximum reacting forces exerted on the dipper of the cable shovel. This algorithm has been implemented into an Excel$^{TM}$ spreadsheet to facilitate user-friendly, "transparent" calculations and built-in data analysis techniques. Its use is demonstrated with a realistic application of a medium-sized shovel. It was found, among others, that the specific energy of cutting exhibits a size effect, such that it decreases as the (-1)-power of the cutting depth for the considered example application.

Numerical Simulation of Air Contaminant Dispersion around Urban City (도심지 빌딩주변 자동차 배가스 분산에 관한 연구)

  • Yu, Kyung-Seok;Ryu, Il-Kwang
    • Journal of environmental and Sanitary engineering
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    • 제21권2호
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    • pp.11-19
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    • 2006
  • Ran numerical analysis about simplicity warm current model (simple turbulence model) to examine closely distributed laying stress on NOx of contaminant that happen in downtown that building is massed and result is as following. Downtown building is massed and transfer of vehicles can know that frequent area receives greatly effect of building. Pollution displays class kind phenomenon striking in the building, class kind done pollution that show high density being mixed with pollution that happen in vehicles being flowed in again side know can. Divide velocity vector of pollution and density change to ancient city and did numerical analysis. Because NOx is flowed in diversion of water neighborhood by continuous this kind in Godo 20m point, density showed density of $0.0907mg/m^3s$, and can know that Banryuhyeon that Pollution strikes in the building at ancient city 30m point is decreased and approaches with freedom flowing without cooperation (cavity) phenomenon remarkably. Because pollution strikes in the building at distance shaft 383m point, class kind do phenomenon that know appeared notedly Nopeungeonmulgwanat between building pollution density $0.067mg/m^3$ head of a families high appear.

Customer Electronic Loyalty towards Online Business: The role of Online Trust, Perceived Mental Benefits and Hedonic Value

  • NGUYEN, Minh Ha;KHOA, Bui Thanh
    • Journal of Distribution Science
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    • 제17권12호
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    • pp.81-93
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    • 2019
  • Purpose: The success of electronic commerce businesses is the ability to retain the customers and inspire their loyalty in online shopping. The purpose of this study is to develop a model to study the effect of perceived mental benefits, online trust, and hedonic value on the elements of electronic loyalty. Research design, data and methodology: Mixed research method was applied in this study with qualitative and quantitative research method. Qualitative data was collected through focus group discussion with electronic commerce experts. Quantitative data was collected through a survey of 917 customers, in which conducted in four cities and one province in Vietnam. SmartPLS software is used for processing quantitative data. Results: The study points out that four constructs of the mental benefit concept, although not entirely, have an impact on online trust and hedonic value. At the same time, two antecedents of electronic loyalty's three elements are online trust and hedonic value. Conclusions: Through the positive influence between the elements in the conceptual model, the study has shown that the perceived mental benefits, online trust, and hedonic value are important factors to shape the electronic loyalty in developing countries, such as Vietnam. This study proposed some scientific and managerial implications.

Analytical approaches to the charging process of stratified thermal storage tanks with variable inlet temperature (변온유입 성층축열조의 충전과정에 대한 해석적 접근)

  • Yoo, Hoseon
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • 제9권1호
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    • pp.43-54
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    • 1997
  • This paper presents an approximate analytical solution to a two-region one-dimensional model for the charging process of stratified thermal storage tanks with variable inlet temperature in the presence of momentum-induced mixing. Based on the superposition principle, an arbitrary-varying inlet temperature is decomposed into inherent discontinuous steps and continuous intervals approximated as a finite number of piecewise linear functions. This approximation allows the temperature of the upper perfectly-mixed layer to be expressed in terms of constant, linear and exponential functions with respect to time. Applying the Laplace transform technique to the model equation for the lower thermocline layer subject to each of three representative interfacial conditions yields compact-form solutions, a linear combination of which constitutes the final temperature profile. A systematic method for deriving solutions to the plug-flow problem having polynomial-type boundary conditions is also established. The effect of adiabatic exit boundary on solution behaviors proves to be negligible under the actual working conditions, which justifies the assumption of semi-infinite domain introduced in the solution procedure. Finally, the approximate solution is validated by comparing it with an exact solution obtained for a specific variation of inlet temperature. Excellent agreements between them suffice to show the necessity and utility of this work.

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The Effect of Worker Heterogeneity in Learning and Forgetting on System Productivity (학습과 망각에 대한 작업자들의 이질성 정도가 시스템 생산성에 미치는 영향)

  • Kim, Sungsu
    • Journal of the Korean Operations Research and Management Science Society
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    • 제40권4호
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    • pp.145-156
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    • 2015
  • Incorporation of individual learning and forgetting behaviors within worker-task assignment models produces a mixed integer nonlinear program (MINLP) problem, which is difficult to solve as a NP hard due to its nonlinearity in the objective function. Previous studies commonly assume homogeneity among workers in workforce scheduling that takes account of learning and forgetting characteristics. This paper expands previous researches by considering heterogeneous individual learning/forgetting, and investigates the impact of worker heterogeneity in initial expertise, steady-state productivity, learning and forgetting on system performance to assist manager's decision-making in worker-task assignments without tackling complex MINLP models. In order to understand the performance implications of workforce heterogeneity, this paper examines analytically how heterogeneity in each of the four parameters of the exponential learning and forgetting (L/F) model affects system performance in three cases : consecutive assignments with no break, n breaks of s-length each, and total b break-periods occurred over T periods. The study presents the direction of change in worker performance under different assignment schedules as the variance in initial expertise, steady-state productivity, learning or forgetting increases. Thus, it implies whether having more heterogenous workforce in terms of each of four parameters in the L/F model is desired or not in different schedules from the perspective of system productivity measurement.

The Roles of Health Consciousness and Service Quality toward Customer Purchase Decision

  • TRAN, Tung Anh;PHAM, Ngan Thi;PHAM, Kien Van;NGUYEN, Linh Cam Tran
    • The Journal of Asian Finance, Economics and Business
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    • 제7권8호
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    • pp.345-351
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    • 2020
  • The study investigates how marketing mix factors are mediated by health consciousness and service quality in creating fresh fruit buying decisions of customers in Vietnam. This study employs samples of customers in Vietnam via the survey questionnaire. The authors have used a total of 256 responses that acquired the valid criteria. The compound of data analysis comprises reliability test, validity test, exploratory factor analysis, group analysis and multiple regression analysis to structure the hypothesized model. Respectively, the structural equation model (SEM) is applied to conduct the multiple multivariate equations. By the assumption of causal-effect relationship between independent variables such as marketing mixed factors, and mediator as health consciousness and service quality, which potentially impact on purchase decision; the SEM method is deployed. The results reveal that consumers have paid no attention to the marketing mix factors, but they care much about service quality and health consciousness. Thus, health consciousness and service quality are effective mediators. These findings are new and contribute to the consumer behavior and retail marketing literature. The findings of this study can provide assistance to managers in the given field to understand more easily the consumer behavior about fresh fruits, then improve their own performance.

Incompressible smoothed particle hydrodynamics modeling of thermal convection

  • Moballa, Burniadi;Chern, Ming-Jyh;Odhiambo, Ernest
    • Interaction and multiscale mechanics
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    • 제6권2호
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    • pp.211-235
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    • 2013
  • An incompressible smoothed particle hydrodynamics (ISPH) method based on the incremental pressure projection method is developed in this study. The Rayleigh-B$\acute{e}$nard convection in a square enclosure is used as a validation case and the results obtained by the proposed ISPH model are compared to the benchmark solutions. The comparison shows that the established ISPH method has a good performance in terms of accuracy. Subsequently, the proposed ISPH method is employed to simulate natural convection from a heated cylinder in a square enclosure. It shows that the predictions obtained by the ISPH method are in good agreements with the results obtained by previous studies using alternative numerical methods. A rotating and heated cylinder is also considered to study the effect of the rotation on the heat transfer process in the enclosure space. The numerical results show that for a square enclosure at, the addition of kinetic energy in the form of rotation does not enhance the heat transfer process. The method is also applied to simulate forced convection from a circular cylinder in an unbounded uniform flow. In terms of results, it turns out that the proposed ISPH model is capable to simulate heat transfer problems with the complex and moving boundaries.