• 전산구조공학
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• 제8권4호
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• pp.17-23
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• 1995

Based on the present FEM study for negative Poisson's-ratio UHMWPE, the following conclusions seem expected. 1) Negative Poisson's-ratio UHMWPE transfers less stresses to the subchondral or peripheral iliac bone, compared to the conventional UHMWPE with Poission's-ratio. 2) Negative Poisson's-ratio cup reduces stresses in UHMWPE cup itself as well as metal backing, and subchondral bone. 3) The reduction in periacetabular mechanical stresses would significantly reduce the rate of fatigue failure and consequently reduce the incidence of aseptic loosening of the cup due to wear or bone resorption.

• 한국항공우주학회지
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• 제31권2호
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• pp.57-62
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• 2003

MEMS(미소전기기계시스템) 박막의 푸와송비 측정을 위한 미소굽힙기법이 제안되었다. 푸와송비 측정에 민감한 쌍원시편(두 개의 원모양)을 설계하고 표면미세가공 공정을 사용하여 제작하였다. 미소압입기로 하중을 가한 쌍원시편의 하중-변위 곡선을 분석하여 푸와송비를 측정할 수 있었다. 제안도니 미소굽힘기법은 표면미세가공에 적합하여 소자제작과정에서의 동시측정이 가능하고(in-situ measurement), 소자가 위치해 있는 작은 영영에서의 물성을 국부적으로 측정할 수 있는 장점이 있다. 제안된 기법을 검증하기 위하여 저압화학기상증착법에 의하여 증착된 2.3㎛ 다결정실리콘(Poly-silicon)의 푸와송비를 측정하였다. 실험에 사용된 다결정실리콘막의 푸와송비는 0.2569 이고 쌍원시편의 강성에 대한 측정표준편차는 2.66% 이었다.

• Steel and Composite Structures
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• 제21권1호
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• pp.57-72
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• 2016

The Poisson ratio reduction of symmetric hygrothermal aged $[{\theta}_m/90_n]_s$ composite laminates containing a transverse cracking in mid-layer is predicted by using a modified shear-lag model. Good agreement is obtained by comparing the prediction models and experimental data published by Joffe et al. (2001). The material properties of the composite are affected by the variation of temperature and transient moisture concentration distribution in desorption case, and are based on a micro-mechanical model of laminates. The transient and non-uniform moisture concentration distribution give rise to the transient Poisson ratio reduction. The obtained results represent well the dependence of the Poisson ratio degradation on the cracks density, fibre orientation angle of the outer layers and transient environmental conditions. Through the presented study, we hope to contribute to the understanding of the hygrothermal behaviour of cracked composite laminate.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.465-472
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• 2003

Creep Poisson's ratio reported by previous experimental studies on multiaxial creep of concrete was controversial. The Poisson's ratio is very sensitive to small experimental error that is inevitably induced, and the sensitivity may cause the controversy. It is difficulty to find out the properties on multiaxial creep of concrete. Therefore, a new approach method to analyze the test results is needed to precisely understand the properties on multiaxial creep of concrete. In this study, microplane model is used as a new approach method in analyzing the multiaxial creep test data. The six data sets extracted from the literature are fitted from regression analysis. Double-power law as a model representing volumetric and deviatoric creep evolutions on microplane is used, and six parameters in volumetric and deviatoric compliances are determined on the assumption that the volumetric and deviatoric creep strains are linearly proportional to corresponding stresses. The optimum fits give very accurate description of the test data. The Poisson's ratio calculated from the optimum fits varies with time and does not depends on the stress states, namely, uniaxial, biaxial, and triaxial stress states. Regression analysis is also performed on the assumption that the Poisson's ratio remains constant with titre. The constant Poisson's ratio can be use in practice without serious error.

• 터널과지하공간
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• 제23권1호
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• pp.66-77
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• 2013

경상분지 퇴적암, 사암, 셰일, 이암, 역암 및 응회암 시료 404개를 대상으로 재하-재재하 가압조건으로 포아송비와 체적 변형률 거동을 분석하였다. 하중증가에 따라 포아송비는 증가, 수렴 및 감소거동을 나타내며 증가거동이 월등히 우세하였다. 체적 변형률 거동은 하중 증가에 따라 정상거동, 양의거동 및 음의거동을 나타내고 있으며 정상거동 양상이 매우 우세하였다. 실무에서 사용하중은 매우 낮은데 이 범위에서 포아송비는 매우 높거나 혹은 낮은 값을 표출하는 바, 이의 적용은 현장시료의 실험을 통한 결과값 선택에서 설계조건을 고려하여 선택해야 할 것이다.

• 비파괴검사학회지
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• 제29권6호
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• pp.519-524
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• 2009

This work presents a simple technique to determine the Poisson's ratio of homogeneous solid material using a pair of low cost PVDF ultrasonic transducers. It is based on transducer's property of generating longitudinal and transversal waves depending on the excitation frequency. Mechanical tests were conducted to validate the proposed method, resulting in a good agreement between ultrasonic and mechanical techniques.

• 한국전산구조공학회논문집
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• 제23권6호
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• pp.727-737
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• 2010

Together with the Young's modulus the Poisson's ratio is another independent material parameter that governs the behavior of a structural system. Therefore, it is meaningful to evaluate separately the influence of the parameter on the random response of the structural system. To this end, a formulation dealing with the spatial randomness in the Poisson's ratio in laminated composite plates is proposed. The main idea of the paper is to transform the fraction form of the constitutive coefficients into the expanded form in an ascending order of the stochastic field function. To validate the adequacy of the formulation, a square plate is chosen and the computation results are compared with those obtained using conventional Monte Carlo simulation. It is observed that the results show good agreement with those by the Monte Carlo simulation(MCS).

• Advances in nano research
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• 제12권4호
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• pp.345-352
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• 2022

In this paper, natural frequency curves are presented for three specific end supports considering distinct values of nonlocal parameter. The vibrational behavior of zigzag double walled carbon nanotubes is investigated using wave propagation with nonlocal effect. Frequency spectra of zigzag (12, 0) double walled carbon nanotubes have been analyzed with proposed model. Effects of nonlocal parameters have been fully investigated on the natural frequency against against variation of Poisson's ratio. A slow increase in frequencies against variation of Poisson's ratio also indicates insensitivity of it for suggested nonlocal model. Moreover, decrease in frequencies with increase in nonlocal parameter authenticates the applicability of nonlocal Love shell model. Also the frequency curves for C-F are lower throughout the computation than that of C-C curves.

• Structural Engineering and Mechanics
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• 제90권6호
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• pp.543-549
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• 2024

The utilization of the fabric materials for lightweight building structures has attracted considerable attention due to the multiple functions and high strength-to-weight ratio. The mechanical properties of the fabric materials evolve with the loading cycle, especially for the Poisson's ratio that requires the full cyclic strain to determine the accurate values. The digital image correlation method has been justified but needs to meet the flexibility and complexity requirements of the fabric materials. This paper thus proposes a modified digital image correlation method to quantify the Poisson's ratio of fabric materials. To obtain the accurate Poisson's ratio of fabric materials in the cyclic experiments using non-contact measuring method, a speckle generation of the digital image correlation method is implemented to obtain the strain distribution and strain characteristics. The uniaxial cyclic experiments for the fabric materials are carried out in the warp, weft and 45° directions. The digital image correlation photos are taken when the material properties become stable in the cyclic loading. The results show that the strain distributions are non-uniform and dependent on the specimen directions. The reliable Poisson's ratios of the fabric materials in the warp, weft and 45° directions are 0.016, 1.2 and 2.6. The strain asymmetry at the maximum strain position is related with the weaving architecture. These observations and results are indispensable to understand the Poisson's ratios of fabric materials and to guide the proper analysis of the large-span membrane structures.

• 응용통계연구
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• 제27권2호
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• pp.345-355
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• 2014

단위 영역의 결점수는 일반적으로 Poisson 분포를 가정한다. 이 Poisson 분포의 확장된 형태로 ZIP(zero-inflated Poisson) 분포를 고려할 수 있는데, 이 모형은 데이터에 0이 많이 관측되는 경우 잘 적합된다고 알려져 있다. 이 논문에서는 ZIP 분포를 따르는 공정을 관리하는 GLR(generalized likelihood ratio) 관리도 절차를 제안하고 있다. 또한 제안된 GLR 관리도의 효율을 기존에 제안된 CUSUM 관리도들과 비교하였다. 그 결과 제안된 GLR 관리도는 모수의 다양한 변화에 대해 효율이 좋거나 또는 효율이 크게 떨어지지 않았고, 특히 CUSUM 관리도에서 모수가 미리 설정한 방향과 다르게 변화했을 때 효율이 크게 나빠지는 문제를 해결할 수 있는 대안이라는 결론을 얻을 수 있었다.