• 소성∙가공
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• 제15권9호
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• pp.635-640
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• 2006

Sandwich sheet with inner structure is expected to find many applications because of high stiffness to mass ratio. However, low resistance to the compressive pressure in the thickness direction is a dominating factor in the formability of sandwich sheet. In this study, sandwich sheet with pyramid type core is considered. For the compressive characteristics in the thickness direction, experiments and finite element simulations are carried out. In the experiment, deformation behavior is observed and discussed as the compression proceeds. It is shown that a corresponding finite element simulation can give a reasonable agreement with experiment in terms of maximum pressure. However, simulation shows some discrepancy from the experiment in terms of compressive pressure-displacement characteristics. The reasons for this discrepancy are studied in the geometrical imperfectness of sandwich sheet. It is also observed that most of deformation is dominated by buckling mode of pyramid legs.

• 전기학회논문지
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• 제59권3호
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• pp.664-668
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• 2010

This paper presents a System-On-a-chip (SoC) for embedded image processing and pattern recognition applications that need Gaussian Pyramid structure. The system is fully implemented into Field-Programmable Gate Array (FPGA) based on the prototyping platform. The SoC consists of embedded processor core and a hardware accelerator for Gaussian Pyramid construction. The performance of the implementation is benchmarked against software implementations on different platforms.

• 한국멀티미디어학회논문지
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• 제19권7호
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• pp.1154-1158
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• 2016

This paper presents a System-On-a-chip for embedded image processing applications that need Gaussian Pyramid structure. The system is fully implemented into Field-Programmable Gate Array (FPGA) based on the prototyping platform. The SoC consists of embedded processor core and a hardware accelerator for Gaussian Pyramid construction. The performance of the implementation is benchmarked against software implementations on different platforms.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.316-319
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• 2008

The L-bending of inner-structure bonded sandwich sheet metal is examined by using a bending die attached to the material testing machine. The specimen is composed of top and bottom layers and a middle layer of pyramid-core structure and each layer is bonded by brazing. The variables chosen for experiments were clearance between punch and die, location of bend line on the specimen surface and clamping type of specimen during L-bending. Effects of these variables on deformation of specimen around die-corner radius were investigated. It was shown that the irregular shapes of recess are formed in the inner layer of bended parts and they greatly depend on working conditions.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.560-563
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• 2008

A condensed model is proposed for the simulation of forming of sandwich sheet with pyramid core. A corresponding finite element analysis for L-type bending is carried out to prove the accuracy and the effectiveness. Simulation results are compared with those of experiment. Deformation shape and post-buckling behavior by simulation are in good agreement with those of experiment for the considerable range of deformation. From the comparison of force-displacement curve, it is shown that the proposed model shows good prediction of the forming force compared to the experiment. Thus, the effectiveness of the proposed method is sufficiently demonstrated.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.266-267
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• 2007

Sandwich sheet with inner structure is expected to find many applications because of high stiffness to mass ratio. In order to simulate forming of sandwich sheet with pyramid core, an effective simulation method is required. Compared to the expensive model using solid elements, cost effective model using simplified elements such as shells and beams is developed. By comparing two models in terms of the cost and accuracy for unit cell deformation, a developed model shows some advantages over the model using solid elements. Evolution of two kind of forming limits, face buckling and core buckling are successfully expressed by developed model. Developed model is also applied in the simulation of square cup drawing and L-type bending. The corresponding experiments are carried out. Deformation shape and wrinkling behavior are compared and discussed. It is found that simulation results using a developed model are in good agreement with experiments.

• Elastomers and Composites
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• 제44권4호
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• pp.378-383
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• 2009

본 연구에서는 피라미드 형상의 코어재를 갖는 복합판재의 성형해석을 위한 축약모델의 사용이 제안되었다. L형 굽힘성형에 대하여 유한요소해석에 의한 해석을 수행하여 제안된 축약모델의 정확성과 유효성이 검증되었다. 성형해석의 정확성을 향상하기 위하여 코어의 보다 상세한 모델링과 코어성형에 의한 가공경화의 고려가 수행되었다. 변형형상과 성형하중곡선에 대하여 비교하였으며 실험과 좋은 일치를 보였다. 힘-하중 곡선의 비교에서 본 해석이 좌굴후변형거동을 잘 예측할 수 있음을 보였다.

• Current Optics and Photonics
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• 제7권5호
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• pp.496-503
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• 2023

We present a detailed analysis of the light extraction efficiency (LEE) of a core-shell nanorod light emitting diode (LED) using finite-difference time-domain (FDTD) simulations. We found that the LEE has a deep dependence on source positions and polarization directions based on the calculated LEE results for every x and z position inside the core-shell nanorod structure. The LEEs are different for the upper part (pyramid) and the lower part (sidewall) of the core-shell nanorod owing to total internal reflection (TIR) and the generated optical modes in the structure. As a result, the LEE of sidewall is much larger than that of pyramid. The averaged LEE of the core-shell nanorod LED is also investigated with variable p-GaN thickness, n-GaN thickness, and height for the design guidelines for the optimized LEE of core-shell nanorod LEDs.

• 수산해양기술연구
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• 제40권4호
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• pp.351-359
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• 2004

본 연구에서는 실선에 적용된 알루미늄 하니콤 샌드위치 판 (AHSP)을 저자가 제안한 심재의 형상이 피라미드인 알루미늄 샌드위치 판의 구조적 특성 및 진동특성을 검토해 보았다. 알루미늄 피라미드 샌드위치 판(APSP)의 기초 자료로 쓰일 수 있게 심재의 각도변화, 높이변화 및 면재와 심재의 두께변화에 따른 구조적 특성을 검토한 결과 APSP가 강도 및 강성에서 우수함을 보였으며, 질량대비 큰 강성 때문에 고유진동수도 다소 크게 평가되었다.

• 전기학회논문지
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• 제60권1호
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• pp.156-160
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• 2011

This paper describes the design and implementation of a System-on-a-Chip (SoC) for pattern recognition to use in embedded applications. The target Soc consists of LEON2 core, AMBA/APB bus-systems and custom-designed accelerators for Gaussian Pyramid construction, lighting compensation and histogram equalization. A new FPGA-based prototyping platform is implemented and used for design and verification of the target SoC. To ensure that the implemented SoC satisfies the required performances, a pattern recognition application is performed.