• Laser Solutions
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• v.16 no.2
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• pp.7-11
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• 2013

Recently advanced laser processing is widely introduced to improve the efficiency of micro part production and to reduce the rate of inferior goods. In this paper the trend of delamination of single layer with both thin copper and polyimide according to the variation of copper thickness was investigated using the coupled thermal-structural analysis of ANSYS. From these analyses results, some conclusions were obtained. Firstly, the maximum temperature was increasing with respect to decrease of copper thickness. Secondly the maximum strain which was in general estimation the main effect of the delamination was observed in case of the copper thickness of $5{\mu}m$. Finally the trend of the delamination was decreasing with increasing the thickness of copper layer.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.79-81
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• 2001

논리적 정확성과 시간적 제약의 만족을 중요시하는 실시간 시스템은 시간이 경과함에 따라 그 기능이 다른 것들로 변화되는 mode change를 요구할 수도 있으며, 그 시간적 제약의 엄격함에 따라 경성 실시간 시스템과 연성 실시간 시스템으로 나눌 수 있다. 유닉스 계열의 운영체제를 확장한 운영체제인 Linux는 연성 실시간을 지원하도록 개발되었으며 이 Linux에 최소의 변경을 가해 경성 실시간을 지원하기 위한 RTLinux가 개발되었다. RTLinux 버전 2.0은 다중 프로세서 시스템을 지원할 수 있도록 재 설계되었지만, 다중 프로세서 환경에서 주어진 태스크들을 각 프로세서에서 정확하고 효율적으로 실행시키기 위한 구체적인 프로세서할당 및 스케줄링 기능은 제공되지 않고 있다. 이러한 사항들을 만족시키기 위해 본 논문에서는 다중 프로세서 환경에서 mode change되는 태스크들이 각각의 mode 범위 내에서 정확하고 효율적으로 실행될 수 있도록 프로세서를 할당하고 스케줄링하는 RTLinux스케줄러를 제시하고 구현하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.57.1-57.1
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• 2011

본 논문에서는 소음을 저감하고 구조적 안전도를 향상시키기 위하여 10kW급 소형 복합재 풍력터빈 블레이드를 해석, 설계하였다. 풍력터빈 블레이드 설계의 기본 사항에 맞추어 블레이드의 스팬 길이는 약 4m, 중량은 30kg 내외가 되도록 설정하였다. 풍력발전기용 블레이드는 경량화가 중요하므로 유리섬유복합재 (glass fiber reinforce pastics), 탄소섬유복합재 (carbon fiber reinforced plastics)가 사용되었다. 본 설계에서는 Carbon prepreg (WSN3KY), Carbon UD(UIN150c), E-glass 등을 사용하였다. 상용 유한요소 프로그램인 NASTRAN을 이용해 Carbon prepreg (WSN3KY), Carbon UD (UIN150c)의 탄소섬유복합재만으로 구성된 블레이드 구조해석을 수행한 결과 중량 조건 및 강도의 안전도는 충족되었으나, 높은 가격을 감안하여 E-glass와 조합하여 블레이드를 재설계할 예정이다. 이번 설계는 소형 풍력발전용 블레이드 설계이므로 좌굴은 고려하지 않았으며, 향후 필요에 따라서 좌굴 및 피로해석도 수행하여 검증할 예정이다. 그리고 블레이드가 복합재로 구성되면 감쇠력이 감소할 가능성이 있다. 탄소섬유복합재로만 구성된 블레이드 구조해석에서도 최대 40cm의 변형이 예측되었으며, 감쇠값 저하 문제도 고려하여야 될 것 같아 BEMT (Blade Element Momentum Theory) 공력모델을 이용해 구조-유체 연성 결합 해석을 수행할 계획이다.

• Journal of Korean Society of Steel Construction
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• v.19 no.6
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• pp.643-653
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• 2007

The ultimate bending strength and flexural ductility performance of longitudinally stiffened plate girders fabricated with mild steel were investigated utilizing nonlinear incremental finite element analysis. AASHTO LRFD (2002) design specifications were reviewed for possible application of longitudinally stiffened plate girders as compact sections. In order to investigate compact section requirements for plate girders with longitudinal stiffeners in webs, a number of full-scale plate girders were modeled and analyzed up to the collapse under pure bending condition. It was found that the slenderness of sub panel of the webs, the stiffness of longitudinal stiffeners, and the slenderness of compression flanges are key parameters governing the flexural ductility of the plate girders. It was also found from finite element analysis that longitudinally stiffened plate girder sections can satisfy compact section requirements both in full plastic moment capacity and flexural ductility requirement. New design equations have been proposed for longitudinally stiffened plate girders to be treated as compact sections.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.6
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• pp.11-20
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• 2014

This paper aims at comparing and analyzing shear buckling characteristics between sinusoidal corrugation shape and trapezoidal one. For this, I adopted the equal-length trapezoidal corrugation and sinusoidal one for the analytical models, and analyzed their shear buckling characteristics through linear buckling analysis and on its theory. Generally, the shear buckling shapes of corrugated steel plates are classified into local buckling, global buckling, and interactive buckling from the two buckling modes. Sinusoidal corrugation shape, unlike trapezoidal corrugation, does not have flat sides, which causes another tendency in shear buckling mode. Especially, the changes and different aspects of shear buckling on the boundary between local buckling and global buckling appear in different corrugation shapes. According to the analysis results, interactive buckling mode appeared on the boundary of local buckling and global bucking in trapezoidal corrugation. However, in the case of corrugated steel plates with sinusoidal configuration, interactive buckling mode appeared in the part where global bucking takes place. Besides, trapezoidal shapes are of advantages on shear buckling resistance in the local buckling section, and so are sinusoidal shapes in the global buckling section.

• Journal of the Korea Concrete Institute
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• v.14 no.4
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• pp.467-473
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• 2002

The purpose of this study is to investigate the inelastic behavior and ductility capacity of reinforced concrete frame subjected to cyclic lateral load and to provide result for developing improved seismic design criteria. A computer program named RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology) for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. The strength increase of concrete due to the lateral confining reinforcement has been taken into account to model the confined concrete. In boundary plane at which each member with different thickness is connected local discontinuous deformation due to the abrupt change in their stiffness can be taken into account by introducing interface element. The effect of number of load reversals with the same displacement amplitude has been also taken into account to model the reinforcing steel. The proposed numerical method for the inelastic behavior and ductility capacity of reinforced concrete frame subjected to cyclic lateral load is verified by comparison with reliable experimental results.

• Journal of the Korean GEO-environmental Society
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• v.12 no.12
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• pp.63-70
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• 2011

Expanded Polystyrene (EPS) is a type of geosynthetic material manufactured with various strengths, unit weights, and dimensions. Due to recent advances in research on EPS, the use of EPS has increased dramatically. This super light weight material has a unit weight of approximately $0.16{\sim}0.47kN/m^3$, equivalent to 6.3~15.7 of that of most natural soils with conditions of fill materials. In spite of this advantage, it is noted that no standard method of resilient modulus test on EPS geofoam was reported and no literature on resilient modulus test methods for EPS geofoam exist. The main object of this study was to investigate feasibility of the resilient modulus of EPS when it was applied for flexible pavement. The investigation of the feasibility was completed based on the results from triaxial tests.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.1
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• pp.90-97
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• 2024

In this study, we employed Highly Ductile Cement Composite (HDCC) to evaluate the flexural performance of a RC slab that simulates the laminating structure of a seashell. To evaluate flexural performance, we produced conventional RC slab specimens, HDCC slab specimens, and HDCC-M slab specimens which biomimics a seashell's layered structure by inserting PE mesh inside the slab made of HDCC. A series of 4-point bending tests were conducted. Experimental results shows the flexural strength of the HDCC-M slab specimen was 1.7 times and 1.2 times higher than that of the RC and HDCC slab specimens, respectively. Furthermore, the ductility was evaluated using the ratio of yield deflection to maximum deflection, and it was confirmed that the HDCC slab test specimen exhibited the best ductility. This is most likely due to the fact that the inserted PE mesh separates the layers and increases ductility, while the HDCC passing through the mesh prevents the loss of load carrying capacity due to layer separation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.3
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• pp.275-282
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• 2014

Particle-reinforced metal matrix composites exhibit a strengthening effect due to the particle size-dependent length scale that arises from the strain gradient, and thus from the geometrically necessary dislocations between the particles and matrix that result from their CTE(Coefficient of Thermal Expansion) and elastic-plastic mismatches. In this study, the influence of the size-dependent length scale on the particle-matrix interface failure and ductile failure in the matrix was examined using finite-element punch zone modeling whereby an augmented strength was assigned around the particle. The failure behavior was observed by a parametric study, while varying the interface failure properties such as the interface strength and debonding energy with different particle sizes and volume fractions. It is shown that the two failure modes (interface failure and ductile failure in the matrix) interact with each other and are closely related to the particle size-dependent length scale; in other words, the composite with the smaller particles, which is surrounded by a denser dislocation than that with the larger particles, retards the initiation and growth of the interface and matrix failures, and also leads to a smaller amount of decrease in the flow stress during failure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.3
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• pp.104-111
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• 2020

The purpose of this study is to investigate the flexural behavior and plastic hinge of reinforced concrete-ECC composite beams. Ordinary portland cement was used as a binder, and high volume fly ash was also used to improve the properties of ECC. An ECC designed in this study showed high tensile strain capacity of 3.0%. Three types of beams were manufactured according to the replacement length of concrete with ECC. From the bending tests, it was found that load-bearing capacity as well as ductility of beam increased with an increase in the replacement length of concrete with ECC. Curvature ductility and plastic hinge length of beam were also increased.