• Title/Summary/Keyword: Empirical Dynamic Model

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LARGE EDDY SIMULATION OF THE COMPRESSIBLE FLOW OVER A OPEN CAVITY (큰에디모사기법을 이용한 공동 주위의 압축성유동 해석)

  • 오건제
    • Journal of the Korean Society of Propulsion Engineers
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    • v.7 no.1
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    • pp.40-48
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    • 2003
  • Large eddy simulation is used to investigate the compressible flow over a open cavity, The sub-grid scale stresses are modeled using the dynamic model. The compressible Navier-Stokes equations are solved with the sixth order accurate compact finite difference scheme in the space and the 4th order Runge-Kutta scheme in the time. The results show a typical flow pattern of the shear layer mode of oscillation over the cavity. The votical disturbances, the roll-up of vorticity, and impingement and scattering of vorticity at the downstream cavity edge can be seen in the shear layer. Predicted acoustic resonant frequency is in good agreement with that of the empirical formula. The mean flow streamlines are nearly horizontal along the mouth of the cavity. The pressure has its minimum value in the vortex core inside the cavity.

A Study on the Dynamic Relationship between Cultural Industry and Economic Growth

  • He, Yugang
    • The Journal of Asian Finance, Economics and Business
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    • v.5 no.4
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    • pp.85-94
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    • 2018
  • The cultural industry is treated as the sunrise industry in modern society. It has taken an increasing role in promoting the economic growth. Due to this, this paper attempts to explore the dynamic relationship between cultural industry and the economic growth. On the grounds of Cobb-Douglas production function, the cultural industry is regarded as a determinant such as the labor input and the capital input to impact the economic growth. Meanwhile, the quarterly datum form 2000-Q1 to 2017-Q4 are employed to perform an empirical analysis via the vector error correction model. The GDP is treated as an independent variable. The input of capital, the input of labor and the total input of cultural industry are treated as dependent variables. Furthermore, a menu of statistical approaches such as the co-integration test and the impulse response function will be used to testify the dynamic relationship between cultural industry and economic growth. Via the Johansen co-integration test, the results report that the cultural industry has a obviously positive effect on economic growth. Through the vector error correction estimation, the results also report that the cultural industry also has a significantly positive effect on economic growth, but less than that of the Johansen co-integration test. This paper provides a view that the cultural industry is a kind of a determinant to promote the economic growth. Therefore, the China's government should pay much attention to the cultural industry construction.

Numerical investigation of the impact of geological discontinuities on the propagation of ground vibrations

  • Haghnejad, Ali;Ahangari, Kaveh;Moarefvand, Parviz;Goshtasbi, Kamran
    • Geomechanics and Engineering
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    • v.14 no.6
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    • pp.545-552
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    • 2018
  • Blast-induced ground vibrations by a significant amount of explosives may cause many problems for mining slope stability. Geological discontinuities have a significant influence on the transmission of dynamic pressure of detonation and according to their position relative to the slope face may have damaging or useful impacts on the slope stability. In this study, the effect of geological discontinuities was investigated by modelling a slope with geological discontinuities through applying the dynamic pressure in three-dimensional discrete element code (3DEC). The geological discontinuities in four states that generally apperceived in mine slopes are considered. Given the advantages of the pressure decay function defined by some researcher, this type of function was used to develop the pressure-time profile. The peak particle velocities (PPV) values were monitored along an axis by utilization of Fish programming language and the results were used as an indicator to measure the effects. As shown in the discontinuity-free model, PPV empirical models are reliable in rocks lacking discontinuities or tightly jointed rock masses. According to the other results, the empirical models cannot be used for the case where the rock mass contains discontinuities with any direction or dip. With regard to PPVs, when the direction of discontinuities is opposite to that of the slope face, the dynamic pressure of detonation is significantly damped toward the slope direction at the surface of discontinuities. On the other hand, when the discontinuities are horizontal, the dynamic pressure of detonation affects the rock mass to a large distance.

Cumulative Effects of Trade Liberalization : The Case of Korean Manufacturing (무역자유화의 동태적 누적효과: 한국 제조업)

  • Park, Soonchan
    • Economic Analysis
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    • v.17 no.4
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    • pp.30-51
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    • 2011
  • Since the previous studies on the effects of trade liberalization implicitly assume that trade liberalization affects economic performance only in any point in time, they inevitably are static. Static evaluations fail to account for cumulative dynamic effects of trade liberalization that affect continuously economic performance. This paper tries to fill this gap of the previous studies in this field, estimating cumulative effects of trade liberalization on economic performance by employing an dynamic version of empirical model. One of important empirical issue is controlling bias from endogeneity. To resolve this problem, this paper employes system GMM that uses lagged first-differences as instruments for level equations and lagged levels as instruments for first-differences equations. It improves upon cross-section estimators because it controls for the potential bias induced by the omission of industry-specific effects and the endogeneity of all regressors. This study investigates the effects of trade liberalization in Korean manufacturing for the period from 1988 to 2005 and finds that cumulative dynamic effects of trade liberalization are present and bigger than static effects.

Wind-induced dynamic response and its load estimation for structural frames of single-layer latticed domes with long spans

  • Uematsu, Yasushi;Sone, Takayuki;Yamada, Motohiko;Hongo, Takeshi
    • Wind and Structures
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    • v.5 no.6
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    • pp.543-562
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    • 2002
  • The main purpose of this study is to discuss the design wind loads for the structural frames of single-layer latticed domes with long spans. First, wind pressures are measured simultaneously at many points on dome models in a wind tunnel. Then, the dynamic response of several models is analyzed in the time domain, using the pressure data obtained from the wind tunnel experiment. The nodal displacements and the resultant member stresses are computed at each time step. The results indicate that the dome's dynamic response is generally dominated by such vibration modes that contribute to the static response significantly. Furthermore, the dynamic response is found to be almost quasi-static. Then, a series of quasi-static analyses, in which the inertia and damping terms are neglected, is made for a wide range of the dome's geometry. Based on the results, a discussion is made of the design wind load. It is found that a gust effect factor approach can be used for the load estimation. Finally, an empirical formula for the gust effect factor and a simple model of the pressure coefficient distribution are provided.

Empirical Study of Dynamic Chinese Corporate Governance Based on Chinese-listed Firms with A Panel VAR Approach

  • Shao, Lin;Zhang, Li;Yu, Xiaohong
    • The Journal of Industrial Distribution & Business
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    • v.8 no.1
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    • pp.5-13
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    • 2017
  • Purpose - In this article, a dynamic model like a VAR is an appropriate choice for estimating the possible interrelationship between ownership structure and firm performance as a dynamic process. Research design, data, and methodology - Data of this work are collected from Chinese stock exchange including 350 Chinese-listed firms during the period of 1999-2012. We hypothesize that this interrelationship dynamically exists between ownership structure and firm performance. To examine the correlation, a panel Vector Auto-regression (PVAR) approach generated by GMM method is utilized to test the possible dynamic relation embedded in corporate governance. Another two dynamic analysis solutions such as orthogonalized impulse-response function and variance decomposition are also used simultaneously. Results - Findings of this study indicate the evidence that dynamically endogenous relationship exists between ownership structure and firm performance. Further, there is a dynamical correlation between investment and performance. Impulse response and variance decomposition illustrate that impact of a shock to variables themselves is the main source for their variability. Conclusions - The conclusion in this study is that there is a bidirectional and inter-temporal effect between proportion of ownership and corporate performance for a long run in accordance with impulse response function. Overall, our results suggest that corporate governance in China is more market oriented.

The Relationship between Dynamic Capabilities, Marketing Capabilities, and Environmental Turbulence: An Empirical Study from China

  • ZHANG, Chun Xia;BANG, Ho Yeol
    • The Journal of Asian Finance, Economics and Business
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    • v.8 no.12
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    • pp.529-540
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    • 2021
  • This study proposes a model and attempts to illustrate the relationship between the frequency of dynamic capability utilization and marketing capabilities, and how market, technology, and competitor turbulence may affect these relationships. The findings suggest that in a highly turbulent environment, frequent use of sensing and integration capabilities may cause certain changes in the impact of marketing capabilities, and in a highly competitive environment, marketing capabilities are positively correlated with company performance. The sample consists of 212 enterprises of China with a three-year vertical data span. The partial least square program Smart-PLS was used for data analysis. The careful management of dynamic capabilities (i.e., relational, sensory, and inclusive) is required to address environmental conditions to achieve capacity alignment and ultimately enhance performance. Our findings demonstrate that relationship capabilities are valuable to the organization and might even help improve its sensing and integrating capabilities. In a highly competitive environment, marketing capabilities contribute the most to company performance. The more frequent the environmental turbulence, the higher the impact of integration capabilities on marketing capabilities. This situation necessitates the organization's usage of dynamic capabilities to modify its marketing approach effectively between stable and turbulent environments.

Do Consumers, Buying Apparel Product Postpone Purchase in the Belief of Price Break? (국내 의류제품 고객은 가격할인을 기다리며 구매를 늦추는가?)

  • Lee, Yun-Kyung;Sun, Jin-Hwang
    • Journal of Global Scholars of Marketing Science
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    • v.15 no.1
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    • pp.81-103
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    • 2005
  • This study intends to examine whether consumers, especially buying apparel product postpone purchase in the beliefs of price break in the near future. For this research objectives, the dynamic price expectation effect model for apparel product is proposed and is applied to weekly sales data and price information of 43 women's apparel brands from a department store over the spring season. The main results are summarized as follows. 1. Dynamic price expectation effect model is developed and the model is more robust to apparel product than Gutenberg model, which is not considered these conditions. 2. By applying the model to empirical data, we find out the price expectation effect in the apparel product; concretely there are 23 brands out of 43 brands. This study confirms the price expectation effects in the apparel product theoretically and extends the research boundary of price expectation effects.

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Development of a Mechanistic Model for Hydrogen Generation in Fuel-Coolant Interactions

  • Lee, Byung-Chul;Park, Goon-Cherl;Chung, Chang-Hyun
    • Nuclear Engineering and Technology
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    • v.29 no.2
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    • pp.99-109
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    • 1997
  • A dynamic model for hydrogen generation by Fuel-Coolant Interactions(FCI) is developed with separate models for each FCI stage, coarse mixing and stratification. The model includes the physical concept of FCI, semi-empirical heat and mass transfer correlation and the concentration diffusion equation with the general non-zero boundary condition. The calculated amount of hydrogen, which is mainly generated in stratification, is compared with the FITS experiments. The model developed in this study shows a good agreement within a range of 10 % fuel oxidation rate and predicts the controlled mechanism of the chemical reaction very well. And this model predicts more accurately than the previous works. It is shown from the sensitivity study that the higher initial temperature of fuel particle is, the larger the reaction rate is. Up to 2700 K of temperature of the particle, the reaction rate increases rapid, which can lead to metal ignition.

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Atomistic modeling for 3D dynamci simulation of ion implantation into crystalline silicon

  • 손명식;강정원;변기량;황호정
    • Proceedings of the IEEK Conference
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    • 1998.06a
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    • pp.421-424
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    • 1998
  • In this paper are presented a newly proposed 3D monte carlo (MC) damage model for the dynamic simulation in order to more accurately and consistently predict the implant-induced point defect distributions of the various ions in crystalline silicon. This model was applied to phosphorus implants for the ULSI CMOS technology developement. In additon, a newly applied 3D-trajectory split method has been implemented into our model to reduce the statistical fluctuations of the implanted impurity and the defect profiles in the relatively large implanted area as compared to 1D or 2D simulations. Also, an empirical electronic energy loss model is proposed for phosphorus and silicon implants. The 3D formations of the amorphous region and the ultra-shallow junction around the implanted region could be predicted by using our model, TRICSI(Transport ions into crystal-silicon).

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