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A Study on Optimal Braking Control Using Adhesion Coefficient
Hanmin Lee,Gildong Kim,Sunghwan Park 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-
The brake systems of the rolling stocks are generally consisted of electrical and mechanical brake systems. Because of its inherent structure of the each brake system, the electrical brake system is mainly used at the high speed range while the mechanical brake system is used at the relatively lower speed range. It is desirable for the rolling stocks to apply the entire electrical brake system. However, since the brake force from electric brake system is not enough to stop the rolling stock within the legal stop distance. Therefore, the mechanical brake system is indispensable to rolling stocks. In general, the vast majority of the world trains are equipped with mechanical braking systems which use compressed air as the force to push block on to wheels or pads on to discs. These mechanical systems are known as air brake or pneumatic brakes. For the air brake system, basically huge scale air compressor is equipped and the long pipe line is complexively connected. Since mass of these air brake components, it is difficult to be a light weight equipment and the long pipe line raise the maintenance problem. In order to overcome these problems of air brake system, the hydraulic brake system is proposed in this research. The hydraulic brake system makes the whole weight of brake equipment be light and large braking force can be applied. Therefore, in this research, the optimal control using adhesion coefficient to apply the hydraulic brake system is reviewed.
Wafer-Level Double-Layer Nonconductive Films for Flip-Chip Assembly
Lee, SeYong,Lee, HanMin,Shin, Ji-Won,Kim, Woojeong,Choi, Taejin,Paik, Kyung-Wook IEEE 2017 IEEE transactions on components, packaging, and ma Vol.7 No.8
<P>3-D chip-stacking packages and 3-D through silicon via (TSV) vertical interconnection are popular flip-chip assembly methods. Cu-pillar/SnAg micro bumps have usually been used for vertical interconnections in the 3-D TSV chip stacking. These vertical interconnections are fabricated using a thermocompression bonding method with nonconductive films (NCFs). The fabrication heat and pressure lead to molten solder wetting the pad. However, the deformed molten solder on the sidewall of the Cu-pillar results in an increase in solder and Cu-pillar contact interfaces. As a result, more Sn is consumed and Kirkendall voids occur at the solder joint. Novel double-layer NCFs (D-NCFs) can solve the problem of solder wetting the sidewall of the Cu-pillar. D-NCFs are two NCF layers, consisting of a fast-curing top NCF layer and a slower-curing bottom NCF layer. The top NCF layer is designed to have a curing onset temperature below the melting temperature of the solder, to prevent the molten solder wetting the Cu-pillar sidewall. The bottom NCF layer, which has a slower curing property and flux ability, helps the molten solder wet the pads. In this paper, D-NCFs were investigated for the wafer-level (WL) processing of 40-mu m fine-pitch Cu-pillar/SnAg micro bump chip assemblies. The D-NCFs properties were first adjusted for WL capability, and then bonding conditions were optimized in terms of solder wetting on the Cu-pillar and electrical interconnection. As a result, the D-NCFs were found to significantly increase the amount of Sn solder remaining between the Cu-pillar/SnAg/Cu interconnection, and also to decrease Sn consumption.</P>
Disassembly Information Model for Sustainable Manufacturing
Hanmin Lee,Seongwhan Park,Shaw C. Feng (사)한국CDE학회 2010 한국CAD/CAM학회 국제학술발표 논문집 Vol.2010 No.8
Manufacturing industry is facing major challenges, such as resources depletion, global climate change, environmental pollution, and ensuring the social well being of future generations. Reuse and recycle become necessary for sustainable development. Disassembly of end-of-service-life products is a key operation to separate a product into reusable and recyclable parts. This paper describes an information model for disassembly in the Unified Modeling Language. A description of the classes and their relationships on disassembly features, disassembly equipment, disassembly workflow, and operations of separations are included in the paper. A case study on a car suspension design is conducted to test the model.