• Title/Summary/Keyword: empirical modeling

Search Result 965, Processing Time 0.027 seconds

Prediction of Ozone Concentration in Suwon by Empirical Kinetic Modeling Approach (EKMA를 이용한 수원시의 장래 오존농도 예측)

  • 서정배;장영기
    • Proceedings of the Korea Air Pollution Research Association Conference
    • /
    • 1999.10a
    • /
    • pp.368-370
    • /
    • 1999
  • 고농도의 오존 농도를 예측ㆍ평가하기 위해서는 대상지역의 기상조건과 풍상쪽(up wind)으로부터의 오존ㆍ오존전구물질(precursor)의 중ㆍ장거리이동, VOCs 및 NOx의 배경농도 및 배출량과 관련된 VOC/NOx의 농도 특성을 파악하는 것이 필수적이다. 따라서 대상지역의 VOCs/NOx의 농도 특성에 따라 차후 고농도의 오존 생성을 예방하기 위한 오존전구물질의 저감대책이 결정되어지므로 대상지역의 광화학특성을 파악하는 것이 선행되어져야 한다.(중략)

  • PDF

Dynamics of Industry Consolidation and Sustainable Competitive Strategy: An Empirical Portrait of Korean Telecommunications Industry (신생 하이테크 산업의 동적 성장 과정과 생존 경쟁 전략: 한국 이동 전화 산업 실증 분석)

  • Kim Bo-Won;Park Gyeong-Bae
    • Proceedings of the Korean Operations and Management Science Society Conference
    • /
    • 2004.10a
    • /
    • pp.17-20
    • /
    • 2004
  • This research is focusing on industry dynamics of Korean Mobile Telecommunications Industry. Industry data from 1997 to April 2004 are used to analyze industry dynamics through variety use of case study and system dynamics modeling. As results, we found the importance of initial endowment, firm reputation, and handset subsidy strategy. Along with these player-based characteristics, government impacts on dynamics of competition are also investigated.

  • PDF

MSET PERFORMANCE OPTIMIZATION THROUGH REGULARIZATION

  • HINES J. WESLEY;USYNIN ALEXANDER
    • Nuclear Engineering and Technology
    • /
    • v.37 no.2
    • /
    • pp.177-184
    • /
    • 2005
  • The Multivariate State Estimation Technique (MSET) is being used in Nuclear Power Plants for sensor and equipment condition monitoring. This paper presents the use of regularization methods for optimizing MSET's predictive performance. The techniques are applied to a simulated data set and a data set obtained from a nuclear power plant currently implementing empirical, on-line, equipment condition monitoring techniques. The results show that regularization greatly enhances the predictive performance. Additionally, the selection of prototype vectors is investigated and a local modeling method is presented that can be applied when computational speed is desired.

Experimental Investigation and Modeling of the Specific Enthalpy Distribution in a Spray Cone

  • Ellendt, N.;Uhlenwinkel, V.
    • Proceedings of the Korean Powder Metallurgy Institute Conference
    • /
    • 2006.09a
    • /
    • pp.58-59
    • /
    • 2006
  • In Spray Forming, specific enthalpy is a key parameter in the deposition process as it influences the thermal condition of the impinging droplets as well as that of the deposit surface. An empirical model for the distribution of specific enthalpy in the spray cone was developed as an easy to handle alternative to numerical models with which the descriptive partial differential equations are solved numerically. The model results were compared with the experimental data to validate its applicability.

  • PDF

Omnichannel's Perception Effect on Omnichannel Use and Customer-Brand Relationship (옴니채널의 지각된 편리성과 유용성이 옴니채널 사용과 소비자-브랜드 관계에 미치는 영향)

  • Yim, Duk-Soon;Han, Sang-Seol
    • Journal of Distribution Science
    • /
    • v.14 no.7
    • /
    • pp.83-90
    • /
    • 2016
  • Purpose - This study focuses on new type distribution channel that named as Omnichannel. Omnichannel is developed from Multichannel which is used in many distribution channels to buy or selling goods. Omnichannel basically needs an Information and Communications Technologies(ICT) to use, so researcher conduct a Technology Acceptance Model(TAM) to research model. Customer-brand relationship was used as dependent variable to focus on the role of Omnichannel. Research design, data, and methodology - The subject of this study is customer who purchase goods or service through omnichannel. Based on the literature from the preceding research analysis of TAM and customer-brand relationship, this study was constructed by the reference to previous studies, final research model design for figure out casual relationship among perceived ease of use, perceived usefulness, omnichannel use and customer-brand relationship. From 2016 February 3 to March 17, questionnaire survey targeted customers who use online and offline channels. 273 questionnaire survey had conducted, then, 252 survey data were available for empirical analysis. Researcher provide descriptive statistics for checking generality. Cronbach's alpha value was used to check the reliability of data. Exploratory factor analysis was used for purification of values and eigenvalue checking. After EFA, Confirmatory factor analysis was used to prepare structural equation modeling with executing structural equation modeling for confirming hypothesis which developed by researcher. Results - The main results of this empirical study are as follows. First, omnichannel's perceived ease of use has positive significant effect on perceived usefulness(estimate: 0.579). Moreover, omnichannel's perceived ease of use and perceived usefulness has positive significant effect on omnichannel use(estimate: 0.325,0.648). Second, using omnichannel has positive significant effect on brand-customer relationship(estimate: 0.521). Every hypothesis adopted as researcher designed. This study found out the intermediate relationship between perceived ease of use and omnichannel use by investigating hypothesis. Conclusions - Base on the empirical result, this study confirmed that TAM theory perceived has relation with omnichannel. First, factors of TAM has positive effect on omnichannel use, so it highlights the important role of customer based interface and usefulness. Especially, perceived usefulness has high indirect influence on ease of use and use of omnichannel. It seems that when customers try to decide use or not use omnichannel, customers focus on percept benefits from omnichannel. Thus, a provider should applicate attractive price table, accurate product or service information and high switching cost strategy to emphasize the usefulness of omnichannel. Second, using omnichannel enhances the relationship between customers and brand, because there are more time and frequency to serve customers. It is important because good relationship between customers can increase the future's financial performance through word of mouse, positive brand image and loyalty to brand or company. Finally, despite of empirical result and implications, this study has limitations. First, there are only a few previous studies about omnicahnnel, so literature reviews are restricted. While set up the factors which can affect the use of omnichannel, next study should be considered with broader theories or models(ex: contingency theory). Second, omnichannel has developed from multichannel, so comparative analysis is needed between these methods because there is a possibility about different forte character of each distribution system on customer's consuming patterns.

A Study on Neural Network Modeling of Injection Molding Process Using Taguchi Method (다구찌방법을 이용한 사출성형공정의 신경회로망 모델링에 관한 연구)

  • Choe, Gi-Heung;Yu, Byeong-Gil;Hong, Tae-Min;Lee, Gyeong-Don;Jang, Nak-Yeong
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.20 no.3
    • /
    • pp.765-774
    • /
    • 1996
  • Computer Integrated Manufacturing(CIM) requires models of manufacturing processes to be implemented on the computer. These models are typically used for determining optimal process control parameters or designing adaptive control systems. In spite of the progress made in the mechanistic modeling, however, empirical models derived from experimental data play a maior role in manufacturing process modeling. This paper describes the development of a meural metwork medel for injection molding. This paper describes the development of a nueral network model for injection molding process. The model uses the CAE analysis data based on Taguchi method. The developed model is, then, compared with the traditional polynomial regression model to assess the applicabilit in practice.

A Study of Modeling PEM Fuel Cell System Using Multi-Variable Optimization Technique for Automotive Applications (다변수 최적화 기법을 이용한 자동차용 고분자전해질형 연료전지 시스템 모델링에 관한 연구)

  • Kim, Han-Sang;Min, Kyoung-Doug;Jeon, Soon-Il;Kim, Soo-Whan;Lim, Tae-Won;Park, Jin-Ho
    • 한국신재생에너지학회:학술대회논문집
    • /
    • 2005.11a
    • /
    • pp.541-544
    • /
    • 2005
  • This study presents the integrated modeling approach to simulate the proton exchange membrane (PEM) fuel cell system for vehicle application. The fuel cell system consisting of stack and balance of plant (BOP) was simulated with MATLAB/Simulink environment to estimate the maximum system power and investigate the effect of BOP component sizing on system performance and efficiency. The PEM fuel cell stack model was established by using a semi-empirical modeling. To maximize the net efficiency of fuel cel1 system, multi-variable optimization code was adopted. Using this method the optimized operating values were obtained according to various system net power levels. The fuel cell model established was co-linked to AVL CRUISE, a vehicle simulation package. Through the vehicle simulation software, the fuel economy of fuel cell powered electric vehicle for two types of driving cycles was presented and compared. It is expected that this study tan be effectively employed in the basic BOP component sizing and in establishing system operation map with respect to net power level of fuel cell system.

  • PDF

Propulsion System Modeling and Reduction for Conceptual Truss-Braced Wing Aircraft Design

  • Lee, Kyunghoon;Nam, Taewoo;Kang, Shinseong
    • International Journal of Aeronautical and Space Sciences
    • /
    • v.18 no.4
    • /
    • pp.651-661
    • /
    • 2017
  • A truss-braced wing (TBW) aircraft has recently received increasing attention due to higher aerodynamic efficiency compared to conventional cantilever wing aircraft. For conceptual TBW aircraft design, we developed a propulsion-and-airframe integrated design environment by replacing a semi-empirical turbofan engine model with a thermodynamic cycle-based one built upon the numerical propulsion system simulation (NPSS). The constructed NPSS model benefitted TBW aircraft design study, as it could handle engine installation effects influencing engine fuel efficiency. The NPSS model also contributed to broadening TBW aircraft design space, for it provided turbofan engine design variables involving a technology factor reflecting progress in propulsion technology. To effectively consolidate the NPSS propulsion model with the TBW airframe model, we devised a rapid, approximate substitute of the NPSS model by reduced-order modeling (ROM) to resolve difficulties in model integration. In addition, we formed an artificial neural network (ANN) that associates engine component attributes evaluated by object-oriented weight analysis of turbine engine (WATE++) with engine design variables to determine engine weight and size, both of which bring together the propulsion and airframe system models. Through propulsion-andairframe design space exploration, we optimized TBW aircraft design for fuel saving and revealed that a simple engine model neglecting engine installation effects may overestimate TBW aircraft performance.

A Study of Modeling PEM Fuel Cell System Using Multi-Variable Optimization Technique for Automotive Applications (다변수 최적화 기법을 이용한 자동차용 고분자 전해질형 연료전지 시스템 모델링에 관한 연구)

  • Kim, Han-Sang;Min, Kyoung-Doug;Jeon, Soon-Il;Kim, Soo-Whan;Lim, Tae-Won;Park, Jin-Ho
    • New & Renewable Energy
    • /
    • v.1 no.4 s.4
    • /
    • pp.43-48
    • /
    • 2005
  • This study presents the integrated modeling approach to simulate the proton exchange membrane [PEM] fuel cell system for vehicle application. The fuel cell system consisting of stack and balance of plant (BOP) was simulated with MATLAB/Simulink environment to estimate the maximum system power and investigate the effect of BOP component sizing on system performance and efficiency. The PEM fuel cell stack model was established by using a semi-empirical modeling. To maximize the net efficiency of fuel cell system, multi-variable optimization code was adopted. Using this method, the optimized operating values were obtained according to various system net power levels. The fuel cell model established was co-linked to AVL CRUISE, a vehicle simulation package. Through the vehicle simulation software, the fuel economy of fuel cell powered electric vehicle for two types of driving cycles was presented and compared. It is expected that this study can be effectively employed in the basic BOP component sizing and in establishing system operation map with respect to net power level of fuel cell system.

  • PDF

Photochemical Modeling of July 1994 High-Ozone Episode in the Greater Seoul Area

  • Kim, Jin-Young;Ghim, Young-Sung;Kim, Yong-Pyo
    • Journal of Korean Society for Atmospheric Environment
    • /
    • v.15 no.E
    • /
    • pp.55-64
    • /
    • 1999
  • The CIT(California Institute of Technology) three-dimensional Eulerian photochemical model was applied to the Greater Seoul Area, Korea for July 24, 1994, a day of the 9-day ozone episode to understand the characteristics of photochemical air pollution problems in the area. The modeling domain was 60km$\times$60km with the girl size of 2km$\times$2km. As the base case emissions, air pollutant emission data of the National Institute of Environmental Research, Korea for the year of 1991 were used with modifications based on EKMA(Empirical Kinetic Modeling Approach) resutls. Comparisons between predicted and observed concentrations showed that the model predicted the peak concentration over the domain reasonably. It was found that the location of the peak ozone concentration was mainly decided by metorological conditions. But the model could not resolve the spatial variations of concentration station by station, which was mainly caused by localized variations in emission and meteorology.

  • PDF