• Earthquakes and Structures
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• 제4권5호
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• pp.527-555
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• 2013

This paper proposes probabilistic models for estimating the seismic demands on reinforced concrete (RC) bridges with base isolation. The models consider the shear and deformation demands on the bridge columns and the deformation demand on the isolation devices. An experimental design is used to generate a population of bridges based on the AASHTO LRFD Bridge Design Specifications (AASHTO 2007) and the Caltrans' Seismic Design Criteria (Caltrans 1999). Ground motion records are used for time history analysis of each bridge to develop probabilistic models that are practical and are able to account for the uncertainties and biases in the current, common deterministic model. As application of the developed probabilistic models, a simple method is provided to determine the fragility of bridges. This work facilitates the reliability-based design for this type of bridges and contributes to the transition from limit state design to performance-based design.

• 한국정밀공학회지
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• 제20권4호
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• pp.174-182
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• 2003

Recently, medical imaging has taken interest on CAD based solution for anatomical part fabrication or finite element analysis of human body. In principle, contours representing object boundary are obtained through image processing techniques. Surface models are then approximated by a skinning method. For this, various methods should be applied to medical images and contours. The major bottleneck of the reconstruction is to remove shape inconsistency between contours and to generate the branching surface. In order to solve these problems, bi-directional smoothing and the composite contour generation method are proposed. Bi-directional smoothing has advantage of removing the shape inconsistency between contours and minimizing shrinkage effect with a large number of iterations. The composite contour by the proposed method ensures smooth transition in branching region.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.273-276
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• 2005

Packing characteristics of amorphous alloy particles were investigated by scanning electron microscopy, compositional analysis, micro-hardness test and finite element method (FEM). Electroless Ni-plating was made on the surface of the Cu-based amorphous particles before consolidation in ambient atmosphere at an intermediate region of glass transition and crystallization temperatures $(T_g\;and\;T_x)$. Some parts of the Ni-layer in the interfaces of the consolidated particles disappeared, while some of them still remained without appreciable change in compositions. No cracks or fractures were found in the particles, which may occur at low temperatures below or near $T_g$ as anticipated by the FEM analysis. Crystallization and change in hardness were not observed after consolidation.

• 소성∙가공
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• 제16권4호
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• pp.229-233
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• 2007

The present work focuses on the prediction of birefringence in injection-molded part and its improvement by rapid mold heating. To calculate birefringence, flow-induced residual stress is computed through a fully three-dimensional injection molding analysis. Then the stress-optical law is applied from which the order of birefringence can be evaluated and visualized. The birefringence patterns are predicted for a rectangular plate with a variation of mold temperature, which shows that the amount of molecular orientation and birefringence level decreases with an increase of mold temperature. The effect of mold temperature on the order of birefringence is also studied for a thin-walled rectangular strip, and the relevant results are compared with experimental measurements. Both predicted and experimental patterns of birefringence are in agreements on the observation that the birefringence level diminishes significantly when the mold temperature is raised over the glass transition temperature.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.555-556
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• 2014

In this paper, topology optimization of two-dimensional acoustic lenses is presented by using the phase field method. The objective of the optimization is to maximize the acoustic pressure at a specified domain inside the acoustic domain for a given frequency, and the constraint is imposed on the amount of the material of the acoustic lens. Topology optimization of two-dimensional acoustic lenses are obtained as the steady state of the phase transition described by the Allen-Cahn equation. The Helmholtz equation modeling the wave propagation is solved by using a finite element method. The effectiveness of the proposed method is verified by applying it for several two-dimensional acoustic lens system design problems.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1828-1830
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• 1998

In this paper, an analysis of microstrip-slotline transiton is performed using a 3D vector Finite Element Method(FEM). On the base of the analysis, power divider/combiner is designed. The optimal structure for equal power division in Ka band is also proposed.

• International Journal of Railway
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• 제5권4호
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• pp.163-166
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• 2012

Many different types of floating slab track have been developed and installed around the world to reduce vibrations and noise originating in the surrounding environment. The main objective of this study is to examine the influence of slab length on behavior of floating slab track based on rail-slab-isolator interaction. The floating slab track is modeled by the connection between rail, slab, isolator, and slab mat in the transition zone. All elements were assembled in a simplified two-dimensional (2D) finite element model (FEM). The maximum length of FST is then investigated based on the maximum additional rail stress criterion as described in UIC 774-3R since no fully accepted design criteria for the slab length in FST systems currently exist.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.899-901
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• 2004

This paper analyzes recording density according to the shape variation of Electric Probe writer, and present a shape design method for improving recording density in perpendicular electric recording device. The gradient of electric field has to be steep to improve recording density because transition region on the media becomes wider when recording. The optimum shape of electrode could be archived by using Response Surface Methodology and 2-Dimensional Finite Element Method.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권5호
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• pp.232-237
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• 2001

The transition avalanche to streamer are presented in atmospheric pressure nitrogen. The results of two-dimensional simulation are obtained by using finite Elements Method combined with Flux Corrected Transport algorithm(FEM-FCT). We modeled the negative streamer which enables to propagate with out and with photoionization. The results of simulation without photoionization and with photoionization are compared. We show that photoionization plays important roles not only in streamer formation but also in streamer propagation.

• Transactions on Electrical and Electronic Materials
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• 제15권1호
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• pp.37-40
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• 2014

A novel memory is reported, in which $Ge_2Sb_2Te_5$ (GST) has been used as a floating gate. The threshold voltage was shifted due to the phase transition of the GST layer, and the hysteretic behavior is opposite to that arising from charge trapping. Finite Element Modeling (FEM) was adapted, and a new simulation program was developed using c-interpreter, in order to analyze the small shift of threshold voltage. The results show that GST undergoes a partial phase transformation during the process of RESET or SET operation. A large $V_{TH}$ shift was observed when the thickness of the GST layer was scaled down from 50 nm to 25 nm. The novel 1 transistor PCM (1TPCM) can achieve a faster write time, maintaining a smaller cell size.