• 한국금형공학회:학술대회논문집
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• 2008.06a
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• pp.31-34
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• 2008

The L-bending of inner-structure bonded sandwich sheet metal is examined to reduce springback and defects of bent parts. The specimen is composed of top and bottom layers and a middle layer with dimple type-inner-structure and each layer is bonded by resistance welding. This specimen with hollow type-inner-structure shows different bending characteristics from the conventional sandwich sheet metals with solid type-inner-structure. The experiments were conducted for two kinds of working conditions, that is, clearance and movement of first bent specimen for second bending. The deformed profile, bend angle and springback were investigated and compared and then the proper working conditions for L-bending of sandwich sheet metal were prosed.

• Journal of Bio-Environment Control
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• v.30 no.4
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• pp.251-256
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• 2021

This study aimed to compare the growth and production of paprika (Capsicum annuum) planted directly on a coir substrate slab according to the bending methods. The existing root direction was bent to 0° (I-type), 90° (L-type), and 180° (U-type), respectively. The weekly average growth such as stem length, diameter, and leaf area tended to be the highest in the I-type bending, but there was no statistical difference. Root weight at 46 weeks after planting was also about 1.3 to 1.7 times heavier in the I-type than the L- and U-type bending. As the yield produced by 330 plants by bending methods, the initial yield was the highest in the U-bending, but then the highest in the I-bending. Accordingly, the total yield was the highest in I-bending. Consequently, when planting on coir substrates directly in paprika cultivation, the I-type bending should be considered most suitable for securing root and plant vigor in the early stages of planting and for enhancing fruiting stability.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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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.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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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.

• Progress in Superconductivity and Cryogenics
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• v.7 no.2
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• pp.11-15
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• 2005

The I$_{c}$ degradation behavior of Bi-2223 tapes bent at RT and 77K were investigated using the bending device invented by Goldacker. Test results on fixing the tape at RT and 17K showed no difference. At 17K and RT bending, the critical strain was 0.67 and 0.50$\%$, respectively, for the VAM-l tape. For the AMSC tape, it was 0.94 and 0.88$\%$, respectively. These results show that there is additional residual stress in the superconducting filaments to be bent at 17K which shifts the formation of cracks into smaller bending radii. This was proved by computational analysis based on the mixture rule of composites. For the VAM-l tape, the Ie degradation behavior using the Goldacker type device shifted to higher strain levels at about 0.5$\%$, as compared with the FRP sample holders which have a critical bending strain of about 0.24$\%$. Also, for the externally reinforced AMSC tape, Ie degradation using the Goldacker type device begins at a higher strain level, at 0.88$\%$ as compared with using FRP sample holders, at 0.74$\%$. The difference between both cases can be explained by the tensile' and thermal stresses that the tapes were subjected to during fixing (soldering) when the FRP sample holders were used.

• Journal of Welding and Joining
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• v.24 no.3
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• pp.55-59
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• 2006

This paper is concerned with a study on cyclic bending load of bus folding door pillar including adhesive bonding and spot welding. Three specimen types were used such as spot welding, I-type adhesive bonding and M-type adhesive bonding in this study. The tensile-shear tests were carried out to evaluate the tensile-shear strength of these three specimen types. Also four-point bending tests were carried out to evaluate the static and dynamic bending load. From the results, using adhesive bonding has a better effect on the static and dynamic bending load than using spot welding. Therefore, manufacturing better structural products can be expected by applying hybrid welding using adhesive and spot welding to those.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.10a
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• pp.53-60
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• 1999

The bending buckling behavior of circular cylindrical shell is studied. The classical analysis by Love type solution and the package program LUSAS for the structural analysis are used to estimate the critical stresses of circular cylindrical shells under axial compression and bending loads. In this paper, the Love type of buckling equation is carefully investigated and numerical results are presented for a wide range of radius-to-thickness (R/t) ratios and length-to-radius (L/R) ratios. These results show that the maximum critical bending stress is about 30~80% greater than the critical compressive stress

• Elastomers and Composites
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• v.44 no.4
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• pp.378-383
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• 2009

In this study, the use of 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. In order to improve the accuracy of forming analysis, more precise modeling of core shape and consideration of work-hardening of previous core forming are carried out. 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 post-buckling behavior.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.861-865
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• 1998

A plate-type linear ultrasonic motor using logitudinal and bending multi-vibration mode was designed and fabricated for the application to card-forwarding device. The stator consisted of PZ-PT-PMS piezoelectric ceramic plate and stainless steel. The performances of the motor were measured. As the experimental results, no-load speed of the motor was 0.6m/s when applied voltage was $80\textrm{V}_{rms}$ in resonance frequency. Starting torque was 1.4 mNm and maximum efficiency was 1.2%.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.9
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• pp.888-896
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• 2011

In this paper, we studied characteristics of the bent antenna febricated on Flexible-PCB. Flexible-PCB consisting of a polyimide has dielectric constant 3.5, thickness 0.125 mm. Proposed antennas which operates at Bluetooth band are a rectangular loop antenna and a loop antenna with inverted-L type stub. We compared the input matching and radiation characteristics of the proposed antennas under eight kinds of bending conditions.