Browsing by Author "Hung, C."

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Active-set sequential quadratic programming method with compact neighbourhood algorithm for the multi-polygon mass production cutting-stock problem with rotatable polygons
(2009-09-01)
Yu, M. T.
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Lin, T. Y.
;
Hung, C.
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機械工程學系
;
Department of Mechanical Engineering
The cutting-stock problem, which considers how to arrange the component profiles on the material without overlaps, can increase the utility rate of the sheet stock, and is thus a standard constrained optimisation problem. In some applications the components should be placed with specific orientations, but in others the components may be placed with any orientation. This study presents an overlap index and it is much more suitable for the active-set SQP method which can reduce the time spend for constraint consideration. Using this method, various object orientations can be considered easily and the number of object on the sheet stock can be improved by up to eight percent. (C) 2009 Elsevier B.V. All rights reserved.
Biomechanical Differences of Coflex-F and Pedicle Screw Fixation in Stabilization of TLIF or ALIF Condition - A Finite Element Study
(2010)
Lo, C. C.
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Tsai, K. J.
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Zhong, Z. C.
;
Hung, C.
;
機械工程學系
Lumbar interbody fusion is a common procedure for treating lower back pain related to degenerative disc diseases. The Coflex-F is a recently developed interspinous spacer, the makers of which claim that it can provide stabilization similar to pedicle screw fixation. Therefore, this study compares the biomechanical behavior of the Coflex-F device and pedicle screw fixation with transforaminal lumbar interbody fusion (TLIF) or anterior lumbar interbody fusion (ALIF) surgeries. This study used a validated three-dimensional finite element model of the L1-L5 lumbar intact spine. To simulate TLIF surgery, left lateral total facetectomy and partial discectomy were performed at the L3/L4 segment of this intact model. An AVS-TL moon cage (Stryker Orthopaedics) was implanted in the L3/L4 segment and using a Coflex-F device or pedicle screw fixation. To simulate ALIF surgery, partial discectomy and total nuclectomy were performed at the L3/L4 segment of this intact model. A SynCage-Open cage (Synthes Spine, Inc.) was implanted into the L3/L4 segment and combined with a Coflex-F device or pedicle screw fixation. A 400 N follower load and a 10 Nm moment were applied to the intact model to mimic four physiological motions. All four implanted models were subjected to 400 N follower load and specific moments in accordance with the hybrid test method. The results show that the Coflex-F device combined with ALIF surgery can provide stability similar to that of pedicle screw fixation combined with TLIF or ALIF surgery. Also, both the posterior instrumentations (Coflex-F and pedicle screw fixation) combined with TLIF surgery had lower stability than combined with ALIF surgery.
Finite element prediction of the lens shape of moulded optical glass lenses
(2011)
Tsai, Y-C
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Hung, C.
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Hung, J-C
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Tseng, S-F
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交大名義發表
Glass moulding is a high-volume fabrication method suitable for producing optical components embedded in computer, communication, and consumer products, such as optical glass lenses in the camera modules of mobile phones. Despite the advantages of glass moulding, several difficulties encountered in the manufacturing process have yet to be overcome. The most critical issue is deviation between the formed lens and the original lens shape design. To overcome this obstacle, this study constructs a precise material model for optical glass with detailed thermal expansion, structural relaxation, and stress relaxation properties obtained from material experiments. This study also uses finite element analysis (FEA) to predict lens shape by incorporating this precise material model at 30 degrees C above At (which is widely adopted by the industry). A subsequent verification moulding experiment demonstrates consistency between the predicted and experimental results. This study establishes and confirms a comprehensive FEA model for predicting the shape of moulded glass lenses.
Sequential quadratic programming method with a global search strategy on the cutting-stock problem with rotatable polygons
(2012-06-01)
Yu, M. T.
;
Lin, T. Y.
;
Hung, C.
;
機械工程學系
;
Department of Mechanical Engineering
The cutting-stock problem, which considers how to arrange the component profiles on the material without overlaps, can increase the utility rate of the sheet stock. It is thus a standard constrained optimization problem. In some applications the components should be placed with specific orientations, but in others the components may be placed with any orientation. In general, the methods used to solve the cutting-stock problem usually have global search strategies to improve the solution, such as the Genetic Algorithm and the Simulated Annealing Algorithm. Unfortunately, many parameters, such as the temperature and the cooling rate of the Simulated Annealing method and the mutation rate of the Genetic Algorithm, have to be set and different settings of these parameters will strongly affect the result. This study formulates the cutting-stock problem as an optimization problem and solves it by the SQP method. The proposed method will make it easy to consider different orientations of components. This study also presents a global search strategy for which the parameter setting is easy.