• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1995년도 춘계학술대회논문집
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• pp.211-223
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• 1995

The purpose of the present study is to examine shearing mechanism through rigidplastic finite element analysis. Difficulties arise in simulating shearing process due tothe narrow shear band formation andlackof proper fracture resolve these difficulties by using adaptive mesh generation crriterion. The simulation results are obtained for various punch clearances and these are compared with existing experimental results. It is shown that FEM simulation technique can be used to further understand the shearing mechanism.

• 한국축산식품학회지
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• 제32권5호
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• pp.578-583
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• 2012

The purpose of this study was to evaluate the ultrastructural and shear force changes of duck breast and leg meat during aging at $0^{\circ}C$. Pekin ducks (45 d old) purchased from Greemud Co. were used for this experiment, and were stored at $0^{\circ}C$ for 7 d in order to determine the changes of the meat structure using transmission electron microscopy (TEM) and shear force. At day 0, A-band, I-band, M-line and Z-line of sarcomeres were seen clearly, but sarcomeres started to lose structure and become extended in length from day 2. With extended aging periods, myofibrils were destroyed and symptoms of aging became more obvious. In the duck breast meat, some myofibrils were also destroyed at the Z-line, but were mainly destroyed at the M-line. The change in structure of duck leg meat over time was similar to that of breast meat. After five days and seven days of aging, mitochondria size and quantity were determined to be increased between the myofibrils. Shear force was decreased over time. From this study, aging at $0^{\circ}C$ was found to negatively influence the ultrastructure and shear force of duck meat.

• 한국지반공학회논문집
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• 제30권4호
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• pp.65-80
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• 2014

본 연구에서는 실제 터널 단면의 형상을 갖는 Trapdoor시험과 수치 해석을 수행하여 주변지반의 거동, 이완하중의 분포 및 점진적인 파괴 현상에 대하여 분석하였다. 지반하중은 Trapdoor의 하강에 따라 급격히 감소 후에 다시 크게 증가하여 일정한 이완하중에 도달하여 아칭효과를 확인 할 수 있었으며, 느슨 모래의 경우가 조밀 모래 보다 상대적으로 큰 값을 나타내었다. 전단대의 형성은 터널 어깨부에서 발생하여 터널 측벽에서 $63^{\circ}$(느슨) 및 $69^{\circ}$(조밀) 방향으로 시작하여 완만한 곡선을 이루며 지표를 향하여 진행하는 형상을 나타내었다. 터널 상부에서의 전단대의 폭원은 1.83b~1.92b(b는 터널폭)로서 기존 제안식으로 구한 값과 유사한 범위를 보였으나, 전단대의 높이는 대심도의 경우 터널고의 1.5~2.0배 정도로서 기존의 제안 값(약 3.0배) 보다 상대적으로 낮은 것으로 나타났다.

• 대한소아치과학회지
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• 제36권3호
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• pp.427-432
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• 2009

본 연구의 목적은 시중에 유통되고 있는 밴드 시멘트들을 종류별로 이용하여 교정용 밴드의 결합강도를 비교하고, 각 시멘트의 파절 양상을 비교하여 교정용 밴드에 대한 사용지침을 마련하는데 도움이 되고자 하였다. 100개의 발거된 인간의 제 3대구치를 이용해 실험군은 총 5개의 군으로 하였으며, 각 군당 시편수가 20개가 되도록 임의적으로 분류하였다. 실험에 사용한 밴드 시멘트는 다음과 같다; Ormco gold, Ultra $Band-Lok^{TM}$, Fuji $Ortho^{TM}$ LC, 3M $Unitek^{TM}$ Multi-Cure Glass Ionomer, $Ketac-Cem^{TM}$. Universal testing machine(Instron Corp., Canton, MA, USA)를 사용하여 최대하중값을 측정하였고, 전단결합강도 값을 계산하였다. 밴드가 탈락한 후, 탈락 부위를 평가하여 법랑질과 시멘트, 시멘트와 밴드 사이로 구분하였다. 밴드의 전단강도는 One-way ANOVA를 이용하여 통계처리 하였으며 Tukey test를 이용하여 검정하였다. 또한 탈락 부위는 Chi-squre analysis를 이용하여 통계 처리하였고, Fisher's exact test로 군간 유의성을 검정하였다. 실험 결과 평균 파절 강도는 Ormco군이 가장 높았고(2.44${\pm}$0.57), Fuji $Ortho^{TM}$군(2.24${\pm}$0.50), $Ketac-Cem^{TM}$군(2.10${\pm}$0.57), 3M $Unitek^{TM}$군(1.82${\pm}$0.43), $Band-Lok^{TM}$군(1.73${\pm}$0.28) 순이었으며, Ormco군은 $Band-Lok^{TM}$군과 3M $Unitek^{TM}$군, Fuji $Ortho^{TM}$군은 $Band-Lok^{TM}$군과만 통계적으로 유의할만한 차이를 보였다(p<0.05). 파절 양상에서 Ormco군과 $Band-Lok^{TM}$군은 서로뿐만 아니라 다른 군과 유의할만한 차이를 보였으며, Fuji $Ortho^{TM}$, 3M $Unitek^{TM}$, $Ketac-Cem^{TM}$ 군 간에는 유의한 차이가 없었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.878-883
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• 2003

To modify some problems of ACI shear provisions, ultimate shear strength equation considering size effect and arch action to compute shear strength in high-strength concrete beams without stirrups is presented in this research. Three basic equations, namely size reduction factor, rho factor, and arch action factor, are derived from crack band model of fracture mechanics, analysis of previous some shear equations for longitudinal reinforcement ratio, and concrete strut described as linear function in deep beams. Constants of basic equations are determined using statistical analysis of previous shear testing data. To verify proposed shear equation for each variable, namely d, , ρ, f/sub c/' and aid, about 250 experimental data are used and proposed shear equation is compared with ACI 318-99 code, CEB-FIP Model code, Kim & Park's equation and Zsutty's equation. While proposed shear equation is simpler than other shear equations, it is shown to be economical predictions and reasonable safety margin. Hence proposed shear strength equation is expected to be applied to practice shear design.

• Structural Engineering and Mechanics
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• 제38권2호
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• pp.249-259
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• 2011

Band windows are commonly used in reinforced concrete structures for the purpose of ventilation and lighting. These applications shorten the lengths of the columns and, consequently, they are subject to higher shear forces as compared with those of hollow frames. Such short columns may cause some damages during earthquakes. Hence, these effects of short columns should be minimized by choosing the dimensions of the band windows properly in order to prevent serious damages in the structure. This can be achieved by taking into account the parameters that are crucial in causing short column effect. Hence, in this study, the effects of those parameters such as the widths and heights of the band windows, the number of bays and storeys within the frame, and the heights of storeys are examined. The effects of the parameters are analyzed using time history analysis. One of the important results of these analyses, is that, the widths of the band windows should be less than 60% of the clear span between the columns, whereas, their heights should be greater than 35% of the clear storey height in order to decrease the short column effects substantially during the design of the reinforced concrete structures.

• 한국지반공학회논문집
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• 제32권3호
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• pp.49-60
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• 2016

일반적으로 흙의 파괴는 전단 변형이 집중되는 영역인 전단면의 형성과 발달에 의해 발생한다. 정규압밀 점성토의 파괴거동을 확인하기 위해 시료 내부의 변형거동 분포에 대해 평가가 필요하다. 본 연구에선 재성형된 카올리나이트 시료에 대해 평면변형률 시험을 수행하였으며, 전단 과정에서 일정 변형률 간격에서 디지털 이미지 해석을 수행하였다. 시험 결과로 도출된 응력-변형률 결과를 통해 4개의 단계를 결정하여 시료의 변형거동과 전단면 특성을 평가하였다.

• 한국생산제조학회지
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• 제9권4호
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• pp.25-33
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• 2000

The reorientations of the atoms by frictional shear deformation at the surface induce cracks at the boundary of the grain. The cracks grow and propagate in regions where the hydrostatic component of stress is least compressive because the compressive component restores the cracks by three-dimensional crystallizing $\pi$-bondings. The materials with Lder's band have very small amount of wear at the initial state. It suggests that initial frictional shear deformation be consumed to the formation of the Lder's band. The average wear amounts of the materials increase very steeply as the øu the stress-strain ratio at the ultimate point, decreases.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 추계 학술논문 발표대회
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• pp.129-133
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• 2008

For the construction of Top-Down structures, it is crucial to have a solid connection between prefounded columns and slabs. This paper presents a new construction method for the connection when using a circular Concrete Filled Tube (CFT) as a prefounded column as an alternative to currently using wide flange type columns. The development of shear studded jackets along with a shear band suitable for the circular shape of the column has been made. The details and mechanism of the connection is explained together with the results of experiments which verified the structural integrity of the connection.

• Interaction and multiscale mechanics
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• 제2권3호
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• pp.235-261
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• 2009

This study illustrates the differences between the elasto-plastic cap model and Lade's model with Cosserat rotation through the analyses of two large-scale geosynthetic-reinforced soil (GRS) retaining wall tests that were brought to failure using a monotonically increasing surcharge pressure. The finite element analyses with Lade's model were able to reasonably simulate the large-scale plane strain laboratory tests. On average, the finite element analyses gave reasonably good agreement with the experimental results in terms of global performances and shear band occurrences. In contrast, the cap model was not able to simulate the development of shear banding in the tests. In both test simulations the cap model predicted failure loads that were substantially less than the measured ones.