• Proceedings of the KSME Conference
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• 2008.11a
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• pp.684-689
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• 2008

In this study, homogenization method combined with the effective interface model for the characterization of properties of the nanoparticulate composites is developed. In order to characterize particle size effect of nanocomposites, effective interface model has been developed. The application range of analytical micromechanics approach is limited because a simple analytical approach is valid only for simple and uniform geometry of fiber particles. Therefore this study focuses on the analysis of mechanical properties of the effect interface through the continuum homogenization method instead of using analytical micromechanics approach. Using the homogenization method, elastic stiffness properties of the effective interface are numerically evaluated and compared with the analytically obtained micromechanics solutions. The suggested homogenization method is expected to be applied to optimization problems for nanocomposite design.

• Computers and Concrete
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• v.25 no.5
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• pp.461-470
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• 2020

This paper presents a numerical study on structural behavior of hammer head pier cap beams, extended on verges and reinforced with carbon fiber reinforced polymer (CFRP) plates. A 3-D finite element (FE) model along with a simplified analytical model are presented. Concrete damage plasticity (CDP) was adapted in the FE model and an analytical approach predicting the CFRP anchor strength was adapted in both FE and analytical model. Total five quarter-scaled pier cap beams with various CFRP reinforcing schemes were experimentally tested and analyzed with numerical approaches. Comparison between experimental results, FE results, analytical results and current ACI guideline predictions was presented. The FE results showed good agreement with experimental results in terms of failure mode, ultimate capacity, load-displacement response and strain distribution. In addition, the proposed strut-and-tie based analytical model provides the most accurate prediction of ultimate strength of extended cap beams among the three numerical approaches.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.3
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• pp.468-474
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• 1997

The chemical composition and hypocholoesterolaemic effect of Nostoc commune were studied. Proximate analysis data, composition of dietary fiber and oxalic acid-ammonium oxalate soluble substance of Nostoc commune were presented. Thirty rats were fed with the one of the following diet for three weeks: The control diet contained 0.75% cholesterol, 0.25% sodium cholate and 5% cellulose powder, CF was cholesterol free, PNC, ONC and RNC diet contained 7.2% powder, 2.2% extracts and 5% residue of Nostoc commune respectively. The lipid components of serum were assayed. The concentration of the total cholesterol was significantly lower in PNC, ONC than the control. The concentration of the total cholesterol was significantly lower in PNC, ONC than the control. The concentration of HDL-choloesterol was significantly higher in PNC than the control. The concentration of LDL, VLDL and chylomicron were comparatively lower in CF and PNC. The concentration of seum triglyceride and phospholipid was lower in PNC group than in the other group.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.824-828
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• 2003

On February 20, 2003, the FCC, the regulator in US, adopted its UNE triennial Review decision, the most sweeping ruling affecting the telecommunications industry since 1996. The FCC adopted a policy of preserving access to the legacy network, while deregulating new, "next generation" networks utilizing fiber facilities. Baby bell like Verizon, SBC strongly insisted that the FCC should relax the unbundling rules to be enlarged the network investment of telecommunication providers. However, this FCC′s determination looks like the partial acceptance of their assertions. This paper mainly will review the existing studies about the impact of UNEs on investment incentives and then find out some implications to be applied in Korea.

• Journal of Mechanical Science and Technology
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• v.14 no.5
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• pp.477-482
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• 2000

This study discusses a non-contact optical technique (electronic speckle pattern interferometry) that is well suited for thermal deformation measurement without any surface preparation and compensating process. Fiber reinforced plastics ($[0]_{16},\;[0/90]_{8S}$) were analyzed by ESPI to determine their thermal expansion coefficients. The thermal expansion coefficient of the transverse direction of a uniaxial composite is evaluated as $48.78{\times}10^{-6}(1/^{\circ}C)$. Also, the thermal expansion coefficient of the cross-ply laminate $[0/90]_{8S}$ is numerically estimated as $3.23{\times}10^{-6}(1/^{\circ}C)$ that is compared with that measured by ESPI.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1280-1285
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• 2003

In the developement of LNG cargo, the current concern focuses on the slim design of insulation layer to increase the LNG carrying capacity. Not only thermal stability with BOR(Boil-Off Rate) but structual stability against the LNG weight and the sloshing phenomenon must be also considered. In this paper, we applied the stitched sandwitch composite called the 3X-Board which is stitched through the core thickness direction using glass fiber to the LNG cargo. We evaluated the thermal and structural characteristics of 3X-Board by changing the core thickness and the material, in order to explore a validity for the slim design through the finite element analysis.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.175-179
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• 1998

The insulation of cable which used for Ultra-High Voltage(UHV) underground power transmission requires excellent insulation capability for high voltage. The typical insulation materials are used XLPE, EPR, etc, but insulation efficiency of these is affected by void or alien substances, existed at the inside of insulators. In this paper, the partial discharge patterns of the defects within insulation cable are observed and analyzed. In this test, void, fiber and metal inclusions which possibly exist in cables, are simulated and investigated the patterns of partial discharges for each models Also the relations between calculated field strength and the insulation breakdown voltage. The experiment shows distinct partial discharge patterns in accordance with the kinds of defects within Insulation cable.

• Electrical & Electronic Materials
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• v.10 no.9
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• pp.922-929
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• 1997

As the size of semiconductor devices shrinks in the horizontal as well as vertical dimension it is difficult to estimate the transport-velocity of electron because they drift in non-equilibrium with a few scattering. In this paper HYbrid Monte Carlo simulator which employs the drift-diffusion model for hole-transport and Monte Carlo model for electron-transport in order to reduce the simulation time and increase the accuracy as well has been developed and applied to analyze the electron-transport in InAlAs/InGaAs HBT which is attractive for an ultra high speed active device in high speed optical fiber transmission systems in terms of the velocity and energy distribution as well as cutoff frequency.

• Journal of Korea Foundry Society
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• v.28 no.4
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• pp.175-178
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• 2008

우주선, 항공기, 수송차량 등은 기능은 집적 다양화 그리고 성능의 고도와 됨에 따라 에너지 효율성을 위해 구조부재의 경량화가 중요성은 증가되고 있다. 경량화 구조부재 재료 중에는 알루미늄 합금, 세라믹, 복합재료 등이 개발되어 우주선, 항공기, 수송차량 구조부재에 적용하기 위한 많은 연구가 이루어지고 있다. 이들 중, 20세기 초 알루미늄합금이 초 경량화 구조부재로서 많이 이용되었다. 본 논문에서는 경량화 재료 중 이방성을 가지는 복합재료를 구조부재에 적용하였다. 그러나 구조부재에 적용되기 위한 이방성 복합 재료는 강한 충격 이후 취성의 특징 때문에 하중과 흡수에너지가 급속히 감소하는 단점을 가지고 있다. 그래서 이방성 복합재료의 각 층간을 완전히 접합하여 성질이 매우 우수한 부재를 제작할 수 있는 Autoclave 성형법으로 제작하였다. 이방성 복합재료 중 CFRP를 설계 메커니즘 변수에 따라 Autoclave 성형을 하고 하중과 흡수에너지가 높음 평가하기 위해 굽힘실험을 하였다.

• Composites Research
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• v.30 no.6
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• pp.410-415
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• 2017

This paper predicted deformation due to thermal residual stress in composites using finite element analysis. Temperature cycle, Model shape, Laminate angle, Stacking sequence, chemical shrinkage of resin, and thermal expansion are affect composite deformation. Compare the results of the analytical model with the actual model of the same shape. This paper suggests that the analytical results can be applied to actual Model.