• 한국도로학회논문집
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• 제16권3호
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• pp.43-50
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• 2014

PURPOSES : The dynamic modulus can be determined by applying the various theories from the Impact Resonance Testing(IRT) Method. The objective of this paper is to determine the best theory to produce the dynamic modulus that has the lowest error as the dynamic modulus data obtained from these theories(Complex Wave equation Resonance Method related to either the transmissibility loss or not, Dynamic Stiffness Resonance Method) compared to the results for dynamic modulus determined by using the Universal Testing Machine. The ultimate object is to develop the predictive model for the dynamic modulus of a Linear Visco-Elastic specimen by using the Complex Wave equation Resonance Method(CWRM) came up for an existing study(S. O. Oyadiji; 1985) and the Optimization. METHODS : At the destructive test which uses the Universal Testing Machine, the dynamic modulus results along with the frequency can be used for determining the sigmoidal master curve function related to the reduced frequency by applying Time-Temperature Superposition Principle. RESULTS : The constant to be solved from Eq. (11) is a value of 14.13. The reduced dynamic modulus obtained from the IRT considering the loss factor related to the impact transmissibility has RMSE of 367.7MPa, MPE of 3.7%. When the predictive dynamic modulus model was applied to determine the master curve, the predictive model has RMSE of 583.5MPa, MPE of 3.5% compared to the destructive test results for the dynamic modulus. CONCLUSIONS : Because we considered that the results obtained from the destructive test had the most highest source credibility in this study, the dynamic modulus data obtained respectively from DSRM, CWRM were compared to the results obtained from the destructive test by using th IRT. At the result, the reduced dynamic modulus derived from DSRM has the most lowest error.

• 한국공간구조학회논문집
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• 제22권2호
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• pp.57-64
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• 2022

In this paper, the physical model and governing equations of a shallow arch with a moving boundary were studied. A model with a moving boundary can be easily found in a long span retractable roof, and it corresponds to a problem of a non-cylindrical domain in which the boundary moves with time. In particular, a motion equation of a shallow arch having a moving boundary is expressed in the form of an integral-differential equation. This is expressed by the time-varying integration interval of the integral coefficient term in the arch equation with an un-movable boundary. Also, the change in internal force due to the moving boundary is also considered. Therefore, in this study, the governing equation was derived by transforming the equation of the non-cylindrical domain into the cylindrical domain to solve this problem. A governing equation for vertical vibration was derived from the transformed equation, where a sinusoidal function was used as the orthonormal basis. Terms that consider the effect of the moving boundary over time in the original equation were added in the equation of the transformed cylindrical problem. In addition, a solution was obtained using a numerical analysis technique in a symmetric mode arch system, and the result effectively reflected the effect of the moving boundary.

• 산업경영시스템학회지
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• 제19권40호
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• pp.1-14
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• 1996

We develop a dynamic demand forecasting model compared to regression analysis model and AutoRegressive Integrated Moving Average(ARIMA) model. The dynamic model can apply to the current dynamic data to forecasts through introducing state equation. A multiple regression model and ARIMA model using given data are designed via the model analysis. The forecasting fitness evaluation between the designed models and the dynamic model is compared with the criterion of sum of squared error.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 추계학술대회 논문집 학회본부
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• pp.345-348
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• 1988

In this paper, the dynamic characteristics of asymmetrical two-phase induction motors are investigated for improving its dynamic performances. The equations which describe the dynamic performance of asymmetrical two-phase induction motors are established and analyzed dynamic characteristics by digital computer simulation. The differential equation is solved by the algorithm of predictor-corrector method. The effects due to machine parameters are analyzed.

• 대한수학교육학회지:수학교육학연구
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• 제27권1호
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• pp.89-112
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• 2017

본 연구에서는 삼차방정식 $x^3+4x=32$의 기하학적 해법을 사례로 하여 삼차방정식 $x^3+ax=b$를 기하학적으로 해결하는 일반화 과정을 분석했다. 연구 결과, 동적 기하 환경을 활용한 문제 해결 과정에서 변수를 동적으로 이해하면서 이미 제시한 일반해를 재해석하고, 더 나아가 또 다른 일반해를 제시할 수 있게 되어 일반화의 수준이 향상되었다. 결론적으로, 문제 해결 과정에서 동적 기하 환경이 변수 이해 및 일반화 수준 향상과 관련해 학생 중심 탐구 수단으로서 유의미한 역할을 할 수 있다는 교수학적 시사점을 도출할 수 있었다.

• 한국전산구조공학회논문집
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• 제29권6호
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• pp.583-590
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• 2016

본 논문은 강형식 기반의 MLS 차분법에 Rayleigh 감쇠효과를 적용한 동적균열진전 해석기법을 제시한다. Rayleigh 감쇠 효과가 반영된 동적 평형방정식과 구성방정식을 도출하고, MLS 미분근사식을 이용하여 지배방정식들을 이산화하였다. 평형방정식뿐만 아니라 구성방정식에서도 감쇠효과를 적절하게 고려하여 기존의 무요소 강정식화 기법에서 고려하지 못했던 비례감쇠 알고리즘을 구현하였다. 시간관련 항을 포함한 동적 평형방정식은 중앙차분법(central difference method)을 이용하여 시간적분 하였고, 속도에 대한 차분식을 lagging시켜 이산화 방정식을 간소화시켰다. 균열의 기하학적 특성은 표면력 '0'인 자연경계 조건을 균열면에 놓인 절점들에 부과하여 묘사하였으며, 균열성장으로 인해 해석단계마다 변하는 절점의 생성 및 이동 효과를 계방정식 구성에 반영하였다. 단일균열과 다중균열을 갖는 수치예제를 통해서 제안된 수치기법의 정확성을 검증하였으며, 비례감쇠 효과의 고려가 동적균열진전 해석결과에 미치는 영향을 보였다.

• 대한수학회보
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• 제52권4호
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• pp.1241-1252
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• 2015

In this paper, we study the dynamical bifurcation of the modified Swift-Hohenberg equation on a periodic interval as the system control parameter crosses through a critical number. This critical number depends on the period. We show that there happens the pitchfork bifurcation under the spatially even periodic condition. We also prove that in the general periodic condition the equation bifurcates to an attractor which is homeomorphic to a circle and consists of steady states solutions.

• Korean Journal of Mathematics
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• 제24권4호
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• pp.637-645
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• 2016

In this paper, we study dynamical Bifurcation of the Burgers-Fisher equation. We show that the equation bifurcates an invariant set ${\mathcal{A}}_n({\beta})$ as the control parameter ${\beta}$ crosses over $n^2$ with $n{\in}{\mathbb{N}}$. It turns out that ${\mathcal{A}}_n({\beta})$ is homeomorphic to $S^1$, the unit circle.

• 농업과학연구
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• 제49권1호
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• pp.61-75
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• 2022

The first purpose of this study is to evaluate the usefulness of pork traceability data, which is monthly time-series data, and to draw implications with regard to its usefulness. The second purpose is to construct a dynamic ecological equation model (DEEM) that reflects the biological characteristics at each growth stage, such as pregnancy, birth and growth, and the slaughter of pigs, using traceability data. With the monthly pig model devised in this study, it is expected that the number of slaughtered animals (supply) that can be shipped in the future is predictable and that policy simulations are possible. However, this study was limited to traceability data and focused only on building a supply-side model. As a result of verifying the traceability data, it was found that approximately 6% of farms produce by mixing great grand parent (GGP), grand parent (GP), parent stock (PS), and artificial insemination (AI), meaning that it is necessary to separate them by business type. However, the analysis also showed that the coefficient values estimated by constructing an equation for each growth stage were consistent with the pig growth outcomes. Also, the model predictive power test was excellent. For this reason, it is judged that the model design and traceability data constructed with the cohort and the dynamic ecological equation model system considering biological growth and shipment times are excellent. Finally, the model constructed in this study is expected to be used as basic data to inform producers in their decision-making activities and to help with governmental policy directions with regard to supply and demand. Research on the demand side is left for future researchers.

• 한국항공우주학회지
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• 제30권3호
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• pp.8-16
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• 2002

헬리콥터 비행 시뮬레이션을 위한 로터 운동방정식을 implicit formulation 형태로 유도하였다. 좌표계 사이의 상대운동을 고려한 일반화된 벡터 kinematics 를 유도하고 이를 적용하여 브레이드 임의 위치 에서 관성속도 및 관성가속도를 구하였다. 유도된 속도 및 가속도 벡터를 이용하여 플래핑, 리드래그 및 토오크 방정식 등을 implicit form으로 유도하였다. 브레이드 스팬에 따른 공간 적분 방법을 살펴보고, 다양한 힌지형상 및 힌지배열 순서에 관계없이 응용영역을 확장할 수 있음을 밝혔다. DAE(Differential Algebraic Equation) 형태를 갖는 본 연구의 결과식을 이용하여 동특성 계산을 위한 시간적분법을 검토하였다.