Browsing by Author "Lee, Yen-Jung"

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Effect of lath microstructure on the mechanical properties of flow-formed C-250 maraging steels
(2007-04-25)
Lee, Yen-Jung
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Kung, Ming-Chueh
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Lee, I-Kang
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Chou, Chang-Pin
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機械工程學系
A solution treated C-250 maraging steel tubing pre-form was cold forward flow-formed into a seamless tube to attain a 79% wall thickness reduction. Various heat treatments were then conducted on the tube to strengthen the material. This study found that although direct aging treatment could generate the tensile strength exceeded the specification's requirement in all the heat treatment attempts, the C-250 steel suffered loss of ductility in percentage elongation. Through "solution + aging" treatment, the steel's ductility was much improved and tensile properties can still meet the specification. The pre-treatment of high homogenization temperature could produce coarse lath martensitic microstructure and result in a decrease of the tensile strength of the C-250 steel. Furthermore, the C-250 steel also showed the presence of seemingly globular precipitates within the lath structure. Detailed discussion of mechanical properties obtained for each of the heat-treated steels in terms of microstructures and metallographic works was presented. (c) 2006 Elsevier B.V. All rights reserved.
On Simultaneous Escape Routing of Length Matching Differential Signalings
(2013-01-01)
Lee, Yen-Jung
;
Chen, Hung-Ming
;
Chin, Ching-Yu
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
In substrate or PCB design, the escape routing problem is considered an essential part and has been widely studied in literature. There are industrial tools and some studies that work on simultaneous escape routing and escape routing of differential pairs on dense circuit boards. However, to route differential pairs simultaneously considering length-matching is still an important and on-going research problem. In this work, inspired by prior state-of-the-arts, we have implemented an integrated approach that achieves simultaneous escape routing considering length matching of differential pairs, our method avoids time-consuming ILP solutions in finding length-matching differential signal paths. Experimental results show that our approach can efficiently and effectively obtain length-matching of differential pairs on simultaneous escape routing to reduce differential-pair skews, compared with B-escape router we reimplemented.