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PCVN 시편 파괴인성의 균열 깊이 영향에 대한 Scaling 모델 해석
박상윤(Sang Yun Park),이호진(Ho Jin Lee),이봉상(Bong Sang Lee) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.4
Standard procedures for a fracture toughness testing require very severe restrictions for the specimen geometry to eliminate a size effect on the measured properties. Therefore, the used standard fracture toughness data results in the integrity assessment being irrationally conservative. However, a realistic fracture in general structures, such as in nuclear power plants, may develop under the low constraint condition of a large scale yielding with a shallow surface crack. In this paper, cleavage fracture toughness tests have been made on side-grooved PCVN (precracked charpy V-notch) type specimens (10 by 10 by 55 ㎜) with various crack depths. The constraint effects on the crack depth ratios were evaluated quantitatively by the developed scaling method using the 3-D finite element method. After the fracture toughness correction from scaling model, the statistical size effects were also corrected according to the standard ASTM E 1921 procedure. The results were evaluated through a comparison with the T0 of the standard CT specimen. The corrected T0 for all of the PCVN specimens showed a good agreement to within 5.4℃ regardless of the crack depth, while the averaged PCVN T0 was 13.4℃ higher than the real CT test results.
Boundary Energy를 이용한 안정적인 손 영역 검출에 관한 연구
박상윤(Sang Yun Park),이응주(Eung Joo Lee) 한국멀티미디어학회 2009 한국멀티미디어학회 학술발표논문집 Vol.2009 No.1
본 연구는 복잡한 배경에서도 손 영역을 안정적으로 검출하는 시스템을 제안하였다. 손 영역의 Boundary Energy를 이용하여 피부색과 비슷한 복잡한 배경에서도 손 영역이 정확히 검출되며 얼굴의 포함 유무와 관계없이 손 영역을 검출 할 수 있다.
SA508 PCVN 시편의 균열깊이에 따른 구속력 손실 평가
박상윤(Sang-Yun Park),이호진(Ho-Jin Lee),이봉상(Bong-Sang Lee) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
In general structures, cleavage fracture may develop under the low constraint condition of large scale yielding with a shallow surface crack. However, standard procedures for fracture toughness testing require very severe restrictions of specimen geometry So the standard fracture toughness data makes the integrity assessment irrationally conservative. In this paper, cleavage fracture toughness tests have been made on side-grooved PCVN (precracked charpy V-notch) type specimens (10 by 10 by 55 ㎜) with varying crack depth. The constraint effects on the crack depth ratios are quantitatively evaluated by scaling model and Weibull stress method using 3-D finite element method. After correction of constraint loss due to shallow crack depths, the statistical size effect are also corrected according to the standard ASTM E 1921 procedure. The results showed a good agreement in the geometry correction regardless of the crack size, while some over-corrections were observed in the corrected values of T?.
전자기장과 열하중을 받는 복합재료 평판의 압전제어에 따른 동특성 변화
박상윤 ( Sang-yun Park ),송오섭 ( Ohseop Song ) 한국복합재료학회 2016 Composites research Vol.29 No.6
본 논문에서 전자기장과 열 하중을 받는 복합재료 평판에 대하여 압전재료를 이용한 압전제어를 수행하였다. 구조물에 가해지는 전자기장과 열 하중, 그리고 구성방정식에서 고려되는 압전효과가 모두 포함된 지배방정식을 FSDT 판 이론에 기초하여 Hamilton 원리에 의하여 유도하였다. 평판의 경계면에서 발생하는 제어력과 제어 모멘트는 비례제어 및 속도제어 로직에 의하여 적용되었다. 전자기장과 열 하중, 그리고 압전효과가 복합재료 평판의 동특성에 미치는 영향에 대하여 고찰하고, 압전효과 및 복합재료의 섬유각 변화를 통하여 복합재 구조물의 동특성을 효과적으로 제어 가능함을 확인하였다. Structural model of laminated composite plate based on the first order shear deformation theory and subjected to a combination of piezoelectric, electromagnetic and thermal fields is established. Coupled equations of motion are derived via Hamilton`s principle on the basis of electromagnetic and piezoelectric equations which are involved in constitutive equations. Proportional control and velocity feedback control logics are applied via boundary control moments and forces. Variations of dynamic chasracteristics of composite plate with collocated piezoelectric sensor and actuators, electromagnetic field and temperature gradient are investigated and it reveals that dynamic characteristics of structure can be effectively controlled by utilizing the piezoelectric effect and ply angles of fiber reinforced composites.