• 한국자기학회:학술대회 개요집
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• 한국자기학회 2010년도 임시총회 및 하계학술연구발표회
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• pp.64-65
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• 2010

• Steel and Composite Structures
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• 제18권3호
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• pp.673-691
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• 2015

In this paper we are particularly focusing on the dynamic crack fatigue life of a 25 m length wind turbine blade. The blade consists of composite materiel (glass/epoxy). This work consisted initially to make a theoretical study, the turbine blade is modeled as a Timoshenko rotating beam and the analytical formulation is obtained. After applying boundary condition and loads, we have studied the stress, strain and displacement in order to determine the critical zone, also show the six first modes shapes to the wind turbine blade. Secondly was addressed to study the crack initiation in critical zone which based to finite element to give the results, then follow the evolution of the displacement, strain, stress and first six naturals frequencies a function as crack growth. In the experimental part the laminate plate specimen with two layers is tested under cyclic load in fully reversible tensile at ratio test (R = 0), the fast fracture occur phenomenon and the fatigue life are presented, the fatigue testing exerted in INSTRON 8801 machine. Finally which allows the knowledge their effect on the fatigue life, this residual change of dynamic behavior parameters can be used to predicted a crack size and diagnostic of blade.

• 한국시스템다이내믹스연구
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• 제8권2호
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• pp.175-190
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• 2007

Stock market volatility largely depends on firms' value and growth opportunities. However, with the globalization of world economy, the effect of the synchronization in major countries is gaining its importance. Also, domestically, the business cycle and cash market of the country are additional factors needed to be considered. The main purpose of this research is to attest the application and usefulness of System Dynamics as a general stock market forecasting tool. Throughout this research, System Dynamics suggests a conceptual model for forecasting a KOSPI(Korea Composite Stock Price Index), taking the factors of the composite stock price indexes in traditional researches. In conclusion of this research, System Dynamics was proved to bean appropriate model for forecasting the volatility and direction of a stock market as a whole. With its timely adaptability, System Dynamic overcomes the limit of traditional statistic models.

• 한국시스템다이내믹스연구
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• 제11권2호
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• pp.29-44
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• 2010

Green growth policy is essentially a dilemmatic policy, because it has two fundamental but conflicting values, environment vs. economy. In this paper, how the dilemma in the green growth policy is perceived by the policy maker is analyzed. Two approach is taken to analyze the dilemma perception by the policy maker, the president of Korea. The first approach is an analysis of policy statements by the president, and the second approach is a cognitive map analysis of his statements. This paper discusses the different findings between two approach and points out the potential power of the cognitive map in finding policy dilemmas.

• 한국시스템다이내믹스연구
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• 제11권1호
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• pp.103-131
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• 2010

This paper aims to investigate a dynamic mechanism underlying the process of knowledge creation and growth with a focus on the 'knowledge-friendly culture' conceptually coined by Davenport and Prusak in 2000. To achieve this objective, key attributes of knowledge are first identified by exploring the generic characteristics and information and interpreting the definitions of knowledge, from which four modes of knowledge growth (Socialization, Externalization, Combination, Internalization) are delineated into a dynamic SECI model by identifying cultural attributes underlying each mode and modeling their casual relationships based on the systems thinking. Further, a series of sensitivity analysis through computer simulation were made to find how 'knowledge-friendly' cultural factors affect the knowledge growth. It is found that individual knowledge is most influenced by organization's cohesion whereas organizational knowledge is most affected by the openness of organization.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1997년도 Proceedings of the 12th KACG Technical Meeting and the 4th Korea-Japan EMGS (Electronic Materials Growth Symposium)
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• pp.223-228
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• 1997

The gas dynamics in a stagnation point upflow OMVPE reactor were studied by Raman spectroscopy. The gas temperature was measured as a function of inlet gas velocity and aspect ratio for both H$_2$ and N$_2$ carrier gases. The centerline temperature gradient was latger at higher inlet velocities and with the use of N$_2$, and only weakly dependent on the aspect ratio. a tracer molecule, CH$_4$, was used to investigate the steady state behavior of reactants in the reactor, and the use of a sweeping flow was found to be a suitable method for preventing wall deposition. The transient switching response of the gas manifold was also investigated. Under certain conditions (low velocities, unmatched flows) recirculation flows were apparent. Numerical calculations of the reactor gas dynamics gave reasonable agreement with experimental results when detailed thermal boundary conditions were included.

• 한국시스템다이내믹스연구
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• 제12권2호
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• pp.5-36
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• 2011

Seoul citizens are currently suffering from high housing price. Home prices have risen more rapidly than salaries so owning a housing unit (apartment, condominium, or single-family home) in Seoul is becoming more difficult than ever. Therefore, this research examines the behavior of average Seoul citizen in owning housing unit in Seoul, Korea, particularly in terms of the length of time required to afford a house unit. This research estimates that it will take about 18.75 years in maximum after getting a job (12.75 years after purchasing the housing unit) to own housing unit in Seoul that is currently valued at $300,000 where the growth rate of income is 2.97% and consumption price increases at a rate of 2.95% per annum. Finally in this research, the optimal growth rate of housing price is estimated ranged from 3.5 to 4.0% minimizing the loan payoff period.

• Kyungpook Mathematical Journal
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• 제57권2호
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• pp.265-285
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• 2017

In this article, a mathematical model is proposed and analyzed to study the delayed dynamics of a system having a predator and two preys with distinct growth rates and functional responses. The equilibrium points of proposed system are determined and the local stability at each of the possible equilibrium points is investigated by its corresponding characteristic equation. The boundedness of the system is established in the absence of delay and the condition for existence of persistence in the system is determined. The discrete type gestational delay of predator is also incorporated on the system. Further it is proved that the system undergoes Hopf bifurcation using delay as bifurcation parameter. This study refers that time delay may have an impact on the stability of the system. Finally Computer simulations illustrate the dynamics of the system.

• 한국결정성장학회지
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• 제11권6호
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• pp.259-263
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• 2001

The continuum model of transient point defect dynamics to predict the concentrations of interstitial and vacancy is established by estimating expressions for the thermophysical properties of intrinsic point defects. And the point defect distribution in a Czochralski-grown 200 mm silicon crystal and the location of oxidation-induced stacking fault ring(OiSF-ring) created during the cooling of crystals are calculated by using the numerical analysis. The purpose of this paper is to show that his approach lead to predictions that are consistent with experimental results. Predicted point defect distributions by transient point defect dynamic analysis are in good qualitative agreement with experimental data under widely and abruptly varying crystal pull rates when correlated with the position of the OiSF-ring .

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2000년도 춘계공동학술대회 논문집
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• pp.330-336
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• 2000

This paper discusses the potential of system dynamics modelling to support balanced scorecard. The balanced scorecard is a conceptual framework for translating an organisation's strategy into a set of performance indicators. These performance indicators are distributed across the 'classic'model's four perspective: Customers, Internal Business Processes, Financial, and Learning and Growth. This balanced scorecard, whilst having significant strength, suffers from the limitation of all performance indicator systems, namely that the interrelationships between indicators are overlooked and there is no way of taking into account the impact of delayed feedback which flows from introduction of new policy and legislative changes. System Dynamics is a methodology for understanding complex problems where there is dynamic behaviour and where feedback impacts significantly on system outcomes. System dynamics provides a rigorous basis for qualitative testing of the effects of performance indicators in complex environments such as health or social security. This can be supplemented with quantitative system dynamics simulation tools that further test the validity of indicators and the business rules implicit in them. System dynamics modelling has an important role to play in extending feedback cycle in performance measurements to a full systems approach.