• 소성∙가공
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• 제16권8호
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• pp.590-595
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• 2007

This paper introduces a new approach to take account of bending history in finite element inverse analysis during sheet metal forming process. A modified membrane element was adopted for finite element inverse analysis so that bending-unbending energy was additionally imposed in the total plastic energy, predicting bending-unbending regions using the geometry of the final shape and tools. An algorithm was applied to a cylindrical cup deep drawing process. The blank shape and the distribution of the thickness strain were compared with those obtained from the incremental finite element analysis in order to evaluate the effect of the bending history. The algorithm reduced the difference between the results of the inverse analysis from those of the incremental analysis due to bending history. The analysis was also carried out with the variation of the thickness of the initial blank to investigate the effect of bending deformation. The results showed that the difference was remarkably reduced as the thickness of the initial blank increased. This indicates that the finite element inverse analysis cooperated with the suggested scheme is useful to obtain more accurate results, especially when bending effects are significant.

• Journal of Welding and Joining
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• 제28권4호
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• pp.41-48
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• 2010

The purpose of this study is to establish the control method of the global bending distortion caused by fabrication process of hatch-cover in a container ship. In order to do it, the transitional behavior of global bending distortion in the deck of hatch-cover during fabrication process was measured by 3-dimensional measuring instrument. From the results, the principal factor controlling the global bending distortion was identified as the bending moment associated with the longitudinal shrinkage force and transverse shrinkage caused by welding and flame heating and the change of the centroid axis of hatch-cover in each fabrication process. Therefore, in this study, with the predictive equations of the longitudinal shrinkage force and transverse shrinkage caused by welding and flame heating and the simplified thermo elastic method, the predictive method for the global bending distortion was established and verified by comparing with the measured result. Based on the results, the amount of reverse bending distortion of main stiffeners was determined to prevent the global bending distortion of hatch-cover.

• 한국광학회지
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• 제12권4호
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• pp.289-293
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• 2001

금속 모세관을 이용하여 일반적인 단일모드 광섬유를 결합함으로써 매크로 벤딩(macro bending)을 측정할 수 있는 광섬유 센서를 제작하였다. 매크로 벤딩에 의한 곡률 반지름이 감소함에 따라 각도 정렬 오차가 증가하여 투과되는 빛의 에너지가 감소하게 되므로 매크로 벤딩을 측정할 수 있었다. 측정 범위는 곡률 반지름 20mm에서 85mm의 영역이었다. 사용한 광섬유 격자의 중심 파장은 각각 1543.3 nm, 1549.5nm이고 최대 벤딩 손실을 -11.19dB였다. 이 센서와 광섬유 브래그 격자를 이용하여 다중점 측정이 가능함을 보였다.

• Journal of the Korean Wood Science and Technology
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• 제24권1호
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• pp.95-99
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• 1996

The bending and compression strength properties of two types Rhus verniciflua specimens, which made of no heat-treated wood and heat-treated wood for urushiol extraction, were measured. The heat-treated specimens were finger-jointed with either resorcinol-phenol or polyurethane resin adhesives, and the vertical type bending strength property was also measured in these specimens. The results obtained are as follows ; 1. The correlation coefficient between the compression strength and specific gravity in the specimens of no heat-treated and heat-treated wood was high. However there was no difference in compression strength property as affected by heat treatment. 2 The correlation coefficient between the bending strength and specific gravity in the specimens of no heat-treated and heat-treated wood was also high. However, there was no difference in bending strength property as affected by heat treatment. 3 The bending test showed high correlation between modulus of elasticity and modulus of rupture for the specimens made of no heat-treated and heat-treated wood. However, there was no difference in bending strength property between the specimens made of heat-treated and no heat-treated wood. 4. The efficiencies of bending strength test on the finger-jointed specimens of heat-treated wood with resorcinol-phenol and polyurethane resin adhesives were 0.85, 0.81. respectively.

• Elastomers and Composites
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• 제41권2호
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• pp.125-130
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• 2006

폴리우레탄(PU)과 폴리에틸렌비닐아세터이트(EVA) 미드솔이 스포츠화의 굽힘 강성에 미치는 영향을 이해하기 위하여 두께와 경도가 다른 중창으로 스포츠화를 제조하여 중창이 스포츠화의 굽힘특성에 미치는 영향을 고찰하였다. 스포츠화의 굽힘 모멘트는 굽힘 각도 $19^{\circ}$에서 나타나기 시작했으며, 이 초기 굽힘각도는 중창의 경도나 두께에 무관한 것으로 나타났다. 중창의 경도 및 두께가 증가함에 따라 스포츠화의 굽힘 모멘트의 값은 현저하게 증가하는 경향을 나타내었다. 발포체 시트나 미드솔 자체만으로 비교하였을 때보다 스포츠화의 굽힘 강성이 미드솔의 두께나 경도 등 신발의 설계에 따라 더욱 크게 영향을 받는 것으로 나타났다.

• 한국초전도ㆍ저온공학회논문지
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• 제11권4호
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• pp.12-15
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• 2009

The $I_c$ degradation behavior of critical current in differently processed YBCO and SmBCO CC tapes with IBAD template has been investigated. It has been known that the residual strain in the CC tape will influence the shape of the $I_c$-strain window; $I_c$ may show a peak value if there exist a residual strain induced in the tape during manufacturing. The difference of residual strain may be resulted from the adopted different deposition techniques. In this study, bending test of CC tapes has been done using the Goldacker bending test rig which can produce both compressive and tensile bending strain continuously or alternately to the sample. For SmBCO CC tapes, in continuous compressive bending test, $I_c$ showed a minimal increase and did not degrade up to the largest strain that can be applied using the bending rig equivalent to 1.15% based on the sample thickness. However, in the case of alternate application of compressive and tensile bending strain, $I_c$ showed a larger degradation and a lower reversible limit when compared with the case of continuous application of the bending strain. When $I_c$ started to degrade significantly at the tension side, the reversibility ended, also at the compression side which is resulted from the permanent deformation like delamination or cracks that was induced due to tensile bending strain.

• 한국운동역학회지
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• 제21권3호
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• pp.327-334
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• 2011

The objective of this study was to develop a scientific approach for investigating Korean dance in detail, and to examine the intense expressions and various movements, which are based on Danjeon breathing. For the purpose, we analyzed the movement changes and distribution of forces resulting from the switch in movement between exhalation and inhalation while bending, which is the most basic movement in Korean dance. The following conclusions were drawn from this study. In Korean dance, bending with breathing involves less back-and-forth-movement and more up-and-down movement, as compared to bending without breathing; this indicates greater body stability and a wider range of movements while bending with breathing. In addition, less time is required for bending with breathing at the point of switching from exhalation to inhalation, and it involves less movement of the supporting leg; thus, vending with breathing involves faster switching from bending movements to extending movements. While bending, the raised leg goes through a less smooth curve while breathing, which indicates stronger movement of the toes. Bending with breathing requires a greater braking force than bending without breathing, and the vertical force, generated by switching from exhalation to inhalation, is transferred to extending movements using the ground load. The results of this study can be potentially employed to investigate the expressions used in Korean dance on th basis of its principle of forces. Korean dance has evolved into various creative forms, and basic analytical studies of these diverse forms and related breathing methods re required in the future.

• Journal of the Korean Wood Science and Technology
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• 제29권2호
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• pp.118-125
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• 2001

본 연구에서는 소나무의 고부가적 이용을 위한 휨가공 특성을 조사하였다. 먼저 휨가공에 영향을 미치는 수종 특성에 대하여 조사하였다. 다음으로 섬유경사각과 휨가공 특성의 관계에 대하여 조사하였다. 시험편은 섬유경사각 $0^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, $90^{\circ}$와 치수 $10mm(T){\times}20mm(R){\times}350mm(L)$로 제작하였다. 휨가공 전의 고주파조사 시간은 30, 60, 90, 120초로 하였다. 본 연구의 결과는 다음과 같다. 1. 섬유경사각의 크기는 휨가공에 있어 탄성계수와 높은 상관이 있었으며, 섬유경사각이 커질수록 휨가공 성능이 크게 증가하였다. 2 강도적인 측면을 고려할 때, 지나치게 큰 섬유경사각은 강도가 약하기 때문에 휩가공채의 용도에 따라 적당한 섬유경사각의 크기가 조정되어야 할 것으로 판단되었다. 3. 휨가공성은 수종에 따라 현저하게 차이가 있는 것으로 조사되었고 수종특성이 명백히 존재하였다.

• 한국의류산업학회지
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• 제6권4호
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• pp.497-502
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• 2004

The mechanical properties of jean slacks to the type of cutting lines in knee region and the bending time, after doing bending 0 times, 500 times, and 1500 times, the effects of whether or not cutting line, the fabric direction of the cutting area, and the number of cutting lines were investigated for tensile, shearing, compression, and mixing value of mechanical properties. The results are as follows: EM to bending times were larger in order of weft

• 대한기계학회논문집A
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• 제34권3호
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• pp.341-346
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• 2010

이종 접합재($\beta-Si_3N_4/S45C$)의 굽힘강도와 인장강도에 미치는 시험편 형상의 영향을 정량적으로 평가하였다. 평균 굽힘강도와 평균 인장강도는 원형단면 시험편이 4각형 단면 시험편보다 약간 높았다. 또한, 초음파(AE)를 이용하여 균열발생응력을 성공적으로 측정할 수 있었으며, 균열발생응력은 굽힘강도의 60~80% 이었다. 아울러, 세라믹측 접합계면 근처의 잔류응력 측정을 굽힘강도 시험전에 X선 회절법에 의해 실시하였으며, 굽힘강도와 균열발생응력은 잔류응력 증가와 더불어 감소하였다. 마지막으로 인장시험에서 굽힘변형률 성분의 영향을 평가하였으며, 인장강도는 굽힘변형률 성분의 증가와 더불어 감소하고 굽힘강도의 약 80%에 해당되었다.