• 한국안전학회지
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• 제13권2호
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• pp.45-53
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• 1998

A method to predict the creep behavior of fiber-reinforced ceramic composites at high temperatures was suggested based on finite element modeling using constituent creep equations of fiber and matrix and showed good agreement with the experimental results. The effects of matrix creep behavior, fiber volume fraction, and residual stresses on the composite creep behavior were also investigated. The results showed that the primary behavior of composites was greatly affected by that of matrix but post-primary behavior was governed by fiber creep characteristics. The increase of fiber volume fraction from 15 vol% to 30 vol% caused the 50% and 40% decrease of steady-state creep rates and total creep strains at $1200^{\circ}C$, 180MPa, respectively. Feasible compressive residual stresses in the matrix caused by different thermal expansion coefficients between the fiber and the matrix could significantly reduce total creep strains of the composite. The creep deformation mechanism in the fiber-reinforced ceramic composites could be explained by the stress transfer and redistribution in the fiber and matrix due to different creep characteristics of its constituents.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
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• pp.257-260
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• 2002

This paper describes the pixel of AMOLED(act ive matrix organic light emitting diode) driving circuit by poly-sl technology. The area per pixel is 278um$\times$278um in 120$\times$160(2.2 inch) Driving the OLEDS with active matrix leads to the lower voltage operation, the lower peak pixel currents and the display with much greater efficiency and brightness The role of the active matrix is to provide a constant current throughout the entire frame time and is eliminating the high currents encountered In the passive matrix approach, This design can support the high resolutions expected by the consumer because the current variation specification is norestricted. The pixel has been designed driving TFT threshold voltage cancellation circuit and wide aperture ratio circuit that communizes 4 pixel. The test simulation results and layout are 11% per threshold-current var Eat ion and 12.5% the aperture ratio of increase.

• 한국전산구조공학회논문집
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• 제17권4호
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• pp.351-363
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• 2004

비보존력을 받는 보-부재의 질량행렬, 탄성강도행릴, circulatory비보존력의 방향변화로 인한 load correction강도행력, 그리고 Winkler 및 Pasternak지반강도행렬을 고려한 운동방정식을 유도하고 divergence 및 flutter에 의한 안정성 해석을 수행한다. 또한 내적 및 외적 감쇠계수를 운동방정식에 포함시킴으로써 감쇠효과를 고려하고, 2차 고유치문제의 해법(quadratic eigen problem solution)을 적용하여 flutter에 미치는 영향을 조사한 후, Beck's column, Leipholz's column 및 Hauger's column에 대하여 비보존력의 방향파라미터 ${\alpha}$에 대한 임계하중의 영향, 내적 및 외적 감쇠계수 및 Winkler 및 Pasternak지반에 의한 임계하중의 영향을 각각 조사한다.

• 한국정보통신학회논문지
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• 제18권4호
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• pp.913-919
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• 2014

본 연구는 지하공사에 적용되는 흙막이 공법 중 4개 공법을 대상으로 영향요인들의 상대적인 가중치를 분석하여 최적의 흙막이 공법을 선정하는 방법에 대한 연구이다. 도심지에 적합한 흙막이 공법 선정을 위한 주요 영향영역과 영향요인들을 설문조사를 통해 분석하여 이를 토대로 매트릭스 분석을 이용하여 흙막이 선정 방법을 제안하였고, 대안별 공법들을 대안 평가기준의 중요도를 통하여 가중치 및 대안 평가기준을 종합 분석함으로써 영향 영역들의 중요도를 평가하여 최적 대안을 분석하였다. 다양한 제한요소를 고려해야 하는 지하 흙막이 공법 선정을 위한 분석 시 IT분야의 정보처리기술과의 융합은 많은 제한조건을 체계적으로 분석하여 최적화하는데 효과적이다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1994년도 봄 학술발표회 논문집
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• pp.57-64
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• 1994

The purpose of this paper is to find minimum surface shape of pneumatic structure using the finite element method. The pneumatic membrane structure is a kind of large deformation problem and very flexible composite material, which mean geomatric nonlinearity. It is not to resist for compression and resultant moment. As the displacement due to internal pressure is getting bigger, it should be considered the direction of forces. It becomes non-linear problem with the non-conservative force. The follower-force depends on the deformation and the direction of force is normal to each element. The solution process is obtained the new stiffness matrix (load correction matrix) depending on deformation through each iterated step. However, the stiffness matrix have not the symmetry and influence on the time of covergence. So in this paper Newton-Rhapson method for solving non-linear problem and for using symmetic matrix, the load direction is changed in each iterated step using the transformation matrix.

• Bulletin of the Korean Chemical Society
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• 제23권11호
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• pp.1541-1544
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• 2002

The concentration of B in steels is important due to its influence on mechanical properties of steel such as hardenability, hot workability, and creep resistance. An analytical method has been developed to determine B in steel samples by high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). National Institute of Standard and Technology Standard Reference Material (NIST SRM) 348a was analyzed to validate the analytical method. The steel sample was digested in a centrifuge bottle with addition of aqua regia and $^{10}B$ spike isotope. Sample pH was then adjusted to higher than 10 to precipitate most matrix elements such as Fe, Cr, and Ni. After centrifugation, the supernatant solution was passed through a cation exchange column to enhance the matrix separation efficiency. B recovery efficiency was about 37%, while matrix removal efficiency was higher than 99.9% for major matrix elements. The isotope dilution method was used for quantification and the determined B concentration was in good agreement with the certified value.

• 소음진동
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• 제7권4호
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• pp.571-578
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• 1997

Recently, many general-purpose packages for fluid-structure interaction problems have been announced. However, they have a lot of limitations to model structures in the fluid-structure interaction problems reasonably. Utilizing general-purpose packages such as MSC/NASTRAN and SYSNOISE, in this paper, a method to slove the radiation scattering problems with some accuracy in the fluid-structure interaction problems was developed. Using a simple model, the results from the presented method here are compared with those from SYSNOISE. The result shows quite a good agreement between the two methods. The problems, which could not be solved by SYSNOISE, were tried to solve with the presented method and results were presented. It was proved that this method could be safely used to solve fluid-structure interaction problems.

• 한국세라믹학회지
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• 제29권1호
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• pp.23-28
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• 1992

Alumina ceramics was reinforced by in-situ formation of La-${\beta}$-aluminate in ${\alpha}$-alumina matrix. The powder mixture of which composition is (100-12x)Al2O3+x(La2O3+11Al2O3) was prepared for the formation of La-${\beta}$-aluminate in ${\alpha}$-alumina matrix. The amount of La-${\beta}$-aluminate in the matrix was controlled by varing x which is number of moles. The dense composite was produced by sintering at 1600$^{\circ}C$ in air or hot-pressing at 1550$^{\circ}C$ under 30 MPa. Bending strength and fracture toughness were increased, resulting from the grain growth inhibition and the crack deflection and crack bridging mechanism when La-${\beta}$-aluminate was produced in ${\alpha}$-alumina matrix.

• 약학회지
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• 제28권4호
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• pp.217-221
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• 1984

Nylon microcapsules of sodium salicylate containing three different matrixes, acacia, gelatin and formalized gelatin, were prepared by interfacial polymerization and the effect of the matrix on the dissolution rate of sodium salicylate from its nylon microcapsule was investigated. The microcapsules were spherical and their particle diameter increased in proportion to the amount of matrix. The surface was different from each other according to the kind and the amount of matrix when observed by the scanning electron microscopy. The dissolution rate of sodium salicylate from its microcapsules was decreased by increase of the amount of matrix and the formalized gelatin most decreased the dissolution rate of drugs.

• 융합경영연구
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• 제7권1호
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• pp.39-50
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• 2019

Purpose - The article views the theoretical basis of adaptation concentric matrix models in the analysis of the financial condition of the organization. Presented the elements counting procedures in the assessment of economic stability. Research design, data, and Methodology - Used the economic indicates in the concentric matrix models. The article views the specific using the concentric matrix models in the analysis of the financial condition of the organization. Results - The concentric matrix models can be adaptation to the analysis of financial conditions of organizations and to the comparative analysis. In the process of analysis of economic stability can be used "a field of efficiency". The classical variant of methods is transformed. The detailed assessment of influence of individual factors defined the additional methods. Conclusions - In the article the methods are demonstrated on the material of organization (Hyundai Elevator Co, China Communications Construction Company).