• Journal of Mechanical Science and Technology
• /
• v.20 no.11
• /
• pp.1891-1897
• /
• 2006

In this study, a new model to predict the effective elastic constants of composites with spherical fillers is proposed. The original Eshelby model is extended to a finite filler volume fraction without using Mori-Tanaka's mean field approach. When single filler is embedded in the matrix, the effective elastic constants of the composite are computed. The composite is in turn considered as a new matrix, where new single filler is again embedded in the matrix. The predicted results by the present model with a series of embedding procedures are compared with those by Mori-Tanaka, self-consistent, and generalized self-consistent models. It is revealed through parametric studies such as stiffness ratio of the filler to the matrix and filler volume fraction that the present model gives more accurate predictions than Mori-Tanaka model without using the complicated numerical scheme used in self-consistent and generalized self-consistent models.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.37 no.10
• /
• pp.887-894
• /
• 2013

Effective thermal conductivity of nanofluids has been predicted by using generalized self-consistent model and modified Eshelby model, which have been used for analysis of material properties of composites. A nanolayer between base fluid and nanoparticle, one of key factors for abrupt enhancement of thermal conductivity of nanofluids, is included in the analysis. The effective thermal conductivities of the nanofluid predicted by the present study show good agreement with those by models in the literature for the nanolayer with a constant or linear thermal conductivity. The predicted results by the present approach have been confirmed to be consistent with experiments for representative nanofluids such as base fluids of water or ethyleneglycol and nanoparticles of $Al_2O_3$ or CuO to be validated.

• Progress in Superconductivity and Cryogenics
• /
• v.21 no.3
• /
• pp.6-12
• /
• 2019

Extended Drude model has been used to obtain information of correlations from measured optical spectra of strongly correlated electron systems. The optical self-energy can be defined by the extended Drude model formalism. One can extract the optical self-energy and the electron-boson spectral density function from measured reflectance spectra using a well-developed usual process, which is consistent with several steps including the extended Drude model and generalized Allen's formulas. Here we used a reverse process of the usual process to investigate the extended Drude analysis when an additional low-energy interband transition is included. We considered two typical electron-boson spectral density model functions for two different (normal and d-wave superconducting) material states. Our results show that the low-energy interband transition might give significant effects on the electron-boson spectral density function obtained using the usual process. However, we expect that the low-energy interband transition can be removed from measured spectra in a proper way if the transition is well-defined or well-known.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.6
• /
• pp.2618-2623
• /
• 2013

A hybrid model is proposed to easily predict the effective thermal conductivity of composites with aligned- and coated-short fibers, whose aspect ratio is not constant. The thermal conductivities of coated fillers are computed by using the generalized self-consistent model, resulting in that composites are simply simulated by the matrix with the equivalent short fibers. Finally, the thermal conductivity of the composites is predicted using the modified Eshelby model. The predicted results by the representative models and hybrid model are compared for the composite with aligned- and coated-short fibers of single aspect ratio. It is demonstrated that the hybrid model can be applied to the composite with aligned- and short-fibers of aspect ratios, 2 and 10, without any difficulties.

• Journal of Korean Society of Transportation
• /
• v.4 no.1
• /
• pp.41-71
• /
• 1986

본 연구는 $\ulcorner$네트웍$\lrcorner$ 평형모형을 이용하여 일반비용극수(Generalized Cost function)의 모형계수를 결정하는 하나의 방법을 제시한다. 이러한 기법은 동일모형을 실현 하기 위해서는 필연적인 과정이다. 기존의 대부분의 방법은 도시통행상 발생되는 통행자의 제비용을 직접 관측하고 수집하여 모형체계를 결정하였지만 본 연구에서는 이미 활용가능한 기종점별 통행실태조사를 이용하여 통행비용을 내생적으로 결정하고 이에 따른 모형체계를 추출한다. 따라서 본 연구는 자료수집상에 야기될 수 있는 제반 문제점의 행결과 동일목적 의 산출과정을 단순화시키고 내적일관성을 추구하였다는 데에 의의가 있다. 연구의 타당성 검토를 위해 $\ulcorner$시카고$\lrcorner$ 지역에 본 모형과 방법론을 적용하고 결과를 분석하였다.