• Communications for Statistical Applications and Methods
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• 제9권3호
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• pp.825-834
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• 2002

Poisson processes are widely used in reliability and survival analysis. In particular, multiple event time data in survival analysis are routinely analyzed by use of Poisson processes. In this paper, we consider large sample properties of nonparametric Bayesian models for Poisson processes. We prove that the posterior distribution of the cumulative intensity function of Poisson processes is consistent under regularity conditions on priors which are Levy processes.

• 한국농공학회논문집
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• 제62권4호
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• pp.45-51
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• 2020

The poisson's ratio was obtained from the effective vertical stress and horizontal stress of consolidation-undrained test. It was analyzed void ratio verse poisson's ratio. At the result, the effective friction angle was increase with relative density increased, was decreased the poisson's ratio. The empirical equation of void ratio and poisson's ratio was showed very high correlation r²=0.846. The empirical equation was showed that the smaller the void ratio in the fine grained soil than granular soil. In the case of 0.85 times the correlation analysis equation of granular and fine grained soil, the experimental results were shown very similarly. In especially, the poisson's ratio prediction results was shown within 5% of the error range, was revalidation 0.85 times the correlation analysis equation using the void ratio. In this study, correlation analysis equation of the granular and fine grained soil was more reliability of the poisson's ratio prediction results apply to the void ratio than dry unit weight.

• Structural Engineering and Mechanics
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• 제19권6호
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• pp.707-720
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• 2005

The bending stress formula that taking into account the transverse deformation is developed for plane-curved, untwisted isotropic beams subjected to loadings that result in deformations in the plane of curvature. In order to account the transverse Poisson contraction effect, a new constitutive relation between force resultants, moment resultants, mid-plane strains and deformed curvatures for a curved plate is derived in a $6{\times}6$ matrix form. This constitutive relation will provide the fundamental basis to the analyses of curved structures composing of isotropic or anisotropic materials. Then, the bending stress formula of a curved isotropic beam can be deduced from this newly developed curved plate theory. The stress predictions by the present analysis are compared to those by the analysis that neglected the Poisson contraction effect. The results show that the Poisson effect becomes more significant as the Poisson ratio and the curvature are getting larger.

• 한국수자원학회논문집
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• 제37권1호
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• pp.13-19
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• 2004

본 연구에서는 포아송 과정을 이용하여 과우해의 재현기간 및 지속특성을 정량화 해 보았다. 대상 지점은 서울 지점으로 하였고 1911년 이후의 자료를 이용하였다. 먼저 포아송 과정을 적용하기 위한 최대 절단수준은 대략 평균에서 표준편차의 50%를 뺀 정도로 결정되었고, 이러한 절단수준에 대해 관측치와 포아송 과정을 비교하였다. 특히, 과우해의 평균 재현기간 및 지속기간은 관측치와 아주 유사한 값을 나타냄을 확인할 수 있었으며, 이는 가뭄을 정량화 하는 경우에도 포아송 과정이 효과적으로 이용될 수 있음을 나타낸다.

• 대한조선학회논문집
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• 제32권3호
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• pp.62-71
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• 1995

비압축성 가정하에 Navier-Stokes 방정식을 이용하여 비정상 점성유동을 수치해석하기 위해서는 매시간 단계에서 타원형 압력 Poisson 방정식의 해를 구해야 하며, 이에 많은 계산시간이 소요된다. 본 논문에서는 직접법을 이용하여 압력 Poisson 방정식을 수치해석하였으며, 분할수 증가에 따른 소요시간 문제를 다루었다. Green 정리를 압력 Poisson 방정식에 적용하면 주어진 문제는 경계치문제로 변환되고, convolution 형의 영역적분은 F.F.T.를 이용하여 계산시간을 단축할 수 있어, 직접법 이용시 소요시간은 경계치문제의 해를 구하는 데에 좌우된다. 직접법의 검증을 위하여 해석해를 알고 있는 경우에 대하여 수치해석하였고, 물체경계조건과 정합문제에 관하여 수치해석 하였는데. 분할수가 (n.n) 시 O($n^{3}$) 미만의 계산시간으로 수치해석할 수 있었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.694-697
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• 2003

Materials with specific micro-structural shape can exhibit negative Poisson's ratio. These materials can be widely used in structural applications because of their high resilience and resistance to impact. Specially, in the field of artificial implant's material, they have many potential applications. In this study, we investigated the Poisson's ratio and the ratio(E$_{e}$/E) of the elastic modulus of rotational particle structures based on structural design variables using finite element method. As the ratio of fibril's length to particle's diameter increased and the ratio of fibril's diameter to fibril's length decreased fixing the fibril's angle with 45 degree. the negative Poisson effect of rotational particle structures increased. The ratio of elastic modulus of these structures decreased with Poisson's ratio. The results show the reasonable values as compared with the previous analytical results.s.

• 충청수학회지
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• 제26권3호
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• pp.501-516
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• 2013

The well-known Vlasov-Poisson equation describes plasma physics as nonlinear first-order partial differential equations. Because of the nonlinear condition from the self consistency of the Vlasov-Poisson equation, many problems occur: the existence, the numerical solution, the convergence of the numerical solution, and so on. To solve the problems, a viscosity term (a second-order partial differential equation) is added. In a viscosity term, the Vlasov-Poisson equation changes into a parabolic equation like the Fokker-Planck equation. Therefore, the Schauder fixed point theorem and the classical results on parabolic equations can be used for analyzing the Vlasov-Poisson equation. The sequence and the convergence results are obtained from linearizing the Vlasove-Poisson equation by using a fixed point theorem and Gronwall's inequality. In numerical experiments, an implicit first-order scheme is used. The numerical results are tested using the changed viscosity terms.

• Computers and Concrete
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• 제32권3호
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• pp.303-311
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• 2023

An analysis of the Poisson's ratios influence of single walled carbon nanotubes (SWCNTs) based on Sander's shell theory is carried out. The effect of Poisson's ratio, boundary conditions and different armchairs SWCNTs is discussed and studied. The Galerkin's method is applied to get the eigen values in matrix form. The obtained results shows that, the decrease in ratios of Poisson, the frequency increases. Poisson's ratio directly measures the deformation in the material. A high Poisson's ratio denotes that the material exhibits large elastic deformation. Due to these deformation frequencies of carbon nanotubes increases. The frequency value increases with the increase of indices of single walled carbon nanotubes. The prescribe boundary conditions used are simply supported and clamped simply supported. The Timoshenko beam model is used to compare the results. The present method should serve as bench mark results for agreeing the results of other models, with slightly different value of the natural frequencies.

• International Journal of Safety
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• 제8권2호
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• pp.26-30
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• 2009

In this study, the Poisson effect on resonant frequency behaviors of the unconstrained piezoelectric patch is investigated. The electromechanical impedance models for the un-bonded patch are derived from the two existing bonded patch models and numerical analysis for a given piezoelectric material is performed. From the analysis, it is found that the Poisson effect is not important as long as the electromechanical impedance model is used to predict the locations of resonant frequencies. However, Poisson effect should be considered when predicting the location of the largest resonant frequency of the patch since the amplitude responses are different with the model used.

• 한국수자원학회논문집
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• 제37권10호
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• pp.813-822
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• 2004

본 연구에서는 경기도 지역을 중심으로 관측자료로 부터 아울러 포아송 과정을 적용하여 가뭄의 재현 및 지속특성을 정량화하고 그 공간분포를 비교 분석해 보았다. 본 연구에서는 관측된 월 강수량 자료를 가뭄지수인 SPI로 변환하여 분석에 이용하였다. 특히, 가뭄의 공간분포 특성 파악을 위해 관측길이가 서로 다른 자료에 포아송 과정을 적용하는 경우의 장ㆍ단점 등을 파악해 보고자 하였다. 본 연구의 결과를 요약하면 다음과 같다. (1) 포아송 과정을 이용한 가뭄의 정량화는 특히 관측기록이 짧은 경우에 유리한 것으로 나타났다. 공간적으로 가까운 위치에 있는 두 지점의 특성이 관측기록의 길이에 덜 민감해 짐에 따라 전체적으로 유사한 특성을 나타냄을 확인할 수 있었다. (2) 지점별 관측기록의 길이가 크게 다른 경우 모형에 의한 가뭄의 공간적 특성 파악이 단순히 관측자료를 이용한 경우에 비해 우월할 수 있다. 본 연구의 경우에 있어서도 모형을 이용한 경우 가뭄의 공간분포가 관측을 직접 분석하여 얻은 가뭄의 공간분포보다 뚜렷하게 나타남을 확인할 수 있었다.