• 한국수학교육학회지시리즈B:순수및응용수학
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• 제3권1호
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• pp.47-52
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• 1996

We consider the third order linear homogeneous differential equation L$_3$(y) = y(equation omitted) ＋ P($\chi$)y' ＋ Q($\chi$)y = 0 (E) P($\chi$) $\geq$ 0, Q($\chi$) ＞ 0 and P($\chi$)/Q($\chi$) is nondecreasing on [${\alpha}$, $\infty$) for some real number ${\alpha}$. (1) In this paper we discuss the distribution of zeros of solutions and a condition of oscillatory for equation (E).(omitted)

• 한국도로학회논문집
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• 제14권6호
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• pp.121-129
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• 2012

PURPOSES : Traffic accidents at intersections have been increased annually so that it is required to examine the causations to reduce the accidents. However, the current existing accident models were developed mainly with non-linear regression models such as Poisson methods. These non-linear regression methods lack to reveal complicated causations for traffic accidents, though they are right choices to study randomness and non-linearity of accidents. Therefore, to reveal the complicated causations of traffic accidents, this study used structural equation methods(SEM). METHODS : SEM used in this study is a statistical technique for estimating causal relations using a combination of statistical data and qualitative causal assumptions. SEM allow exploratory modeling, meaning they are suited to theory development. The method is tested against the obtained measurement data to determine how well the model fits the data. Among the strengths of SEM is the ability to construct latent variables: variables which are not measured directly, but are estimated in the model from several measured variables. This allows the modeler to explicitly capture the unreliability of measurement in the model, which allows the structural relations between latent variables to be accurately estimated. RESULTS : The study results showed that causal factors could be grouped into 3. Factor 1 includes traffic variables, and Factor 2 contains turning traffic variables. Factor 3 consists of other road element variables such as speed limits or signal cycles. CONCLUSIONS : Non-linear regression models can be used to develop accident predictions models. However, they lack to estimate causal factors, because they select only few significant variables to raise the accuracy of the model performance. Compared to the regressions, SEM has merits to estimate causal factors affecting accidents, because it allows the structural relations between latent variables. Therefore, this study used SEM to estimate causal factors affecting accident at urban signalized intersections.

• 호남수학학술지
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• 제27권2호
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• pp.205-209
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• 2005

In this paper we discuss on the uniquenss of the solution of partial differential equations: (1) $${\frac{{\partial}w}{{\partial}{\bar{z}}}}=F(z,\;w,\;{\frac{{\partial}w}{{\partial}z}}}+G(z,\;w.{\bar{w})$$ in the sobolev space $W_{1,p}(D)$.

• Korean Journal of Mathematics
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• 제28권2호
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• pp.295-309
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• 2020

In this paper we study the growth of solutions of some non-linear complex differential equations in connection to Brück conjecture using the theory of complex differential equation.

• 대한수학회보
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• 제54권2호
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• pp.667-677
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• 2017

Let $F{\subseteq}{\mathbb{P}}^3$ be a smooth surface of degree $3{\leq}d{\leq}9$ whose equation can be expressed as either the determinant of a $d{\times}d$ matrix of linear forms, or the pfaffian of a $(2d){\times}(2d)$ matrix of linear forms. In this paper we show that F supports families of dimension p of pairwise non-isomorphic, indecomposable, Ulrich bundles for arbitrary large p.

• 한국방사선학회논문지
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• 제7권1호
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• pp.93-98
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• 2013

이 연구의 목적은 6 MV 광자 빔에 대한 광자극형광나노닷선량계(OSLnD)의 교정을 조사하는 데 있다. OSLnD의 선량반응 분석으로부터 선형 및 비선형 교정의 선량범위들은 결정을 하였다. 교정 및 교정식의 정확성을 평가하기 위하여 교정 및 품질관리선량계의 세트들은 만들어서 사용하였다. 교정들은 각각 0~300 cGy 및 20~1300 cGy 선량범위에서 선형 및 비선형적으로 수행하였다. 교정의 오차들은 선형 및 비선형 교정에 대하여 품질관리선량계들의 측정으로부터 각각 0.1% 이하로 얻었다. 이 연구는 6 MV 광자 빔에 대한 OSLnD의 교정식을 제공한다.

• Steel and Composite Structures
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• 제14권1호
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• pp.73-83
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• 2013

In this paper Hamiltonian Approach (HA) have been used to analysis the nonlinear free vibration of Simply-Supported (S-S) and for the Clamped-Clamped (C-C) Euler-Bernoulli beams fixed at one end subjected to the axial loads. First we used Galerkin's method to obtain an ordinary differential equation from the governing nonlinear partial differential equation. The effect of different parameter such as variation of amplitude to the obtained on the non-linear frequency is considered. Comparison of HA with Runge-Kutta 4th leads to highly accurate solutions. It is predicted that Hamiltonian Approach can be applied easily for nonlinear problems in engineering.

• 항공우주기술
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• 제13권2호
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• pp.60-65
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• 2014

본 논문에서는 적분 행렬을 이용한 수치적분 방법을 연구하였다. 비선형 운동방정식에 대한 빠른 수치적분을 수행하기 위해, 적분 행렬을 이용한 개선된 fixed point iteration 방법을 소개한다. 예제로는 궤도 운동에 대한 수치적분 예를 고려한다. 수치 예제를 통하여, 본 논문에서 연구되는 알고리듬이 적분의 정밀도는 크게 저하시키지 않음과 동시에, 계산시간 측면에서 효과적이라는 것을 보인다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.800-804
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• 2005

In this paper, the radiated sound pressure induced by low velocity impact is obtained by solving the Rayleigh integral equation. For structurally radiated noise, the sound field is directly coupled to the structural motion. Therefore the impact response should be analyzed. It is well known that the presence of the delamination in a composite laminate introduces a local flexibility which changes the dynamic characteristic of the structure. The 2-D simplified delamination model is used to analyze the impact response. And the 3-D non-linear finite element model is developed using gap element to avoid the overlap and penetration between the upper and lower sub-laminates at delamination region. Predicted impact response using 2-D equivalent delamination model are compared with the numerical ones from the 3-D non-linear finite element model.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.731-736
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• 2000

The vibration of an axially moving string is studied when the string has geometric non-linearity and translating acceleration. Based upon the von karman strain theory, The equation for the longitudinal vibration is linear and uncoupled, while the equation for the transverse vibration is non-linear and coupled between the longitudinal and transverse deflections. The governing equations are discretized by using the Galerkin approximation. With the discretized nonlinear equations, the time responses are investigated by using the generalized-${\alpha}$ method.