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Carbon/epoxy composite foot structure for biped robots
Lee, Jinyi,Lee, Dongyoung,Park, Jongwon,Choi, Ilbeom,Lim, Jun Woo,Kim, Soohyun,Lee, Dai Gil Elsevier 2016 COMPOSITE STRUCTURES -BARKING THEN OXFORD- Vol.140 No.-
<P><B>Abstract</B></P> <P>Although aluminum structures are generally used for robot structures due to their high specific strength, aluminum feet for fast running biped robots are vulnerable to fatigue failure due to the low fatigue limit and low vibration damping of aluminum structures under repeated impact loadings on the feet. On the other hand, carbon/epoxy composites not only have a much higher specific fatigue limit but also have a higher material damping than that of aluminum.</P> <P>In this study, a carbon/epoxy composite foot structure of a biped robot was developed. The composite foot structure was designed for optimum performances such as weight saving, natural frequency, damping, and compliance for vibration isolation. Then its performances were analytically and experimentally obtained and compared with those of an aluminum foot structure. Finally, an optimum configuration of the composite foot structure was suggested for the reliable dynamic performance of the biped robot.</P>
스프레이 분사에서 나오는 연료 입자의 크기 및 연료비의 홀로그래픽적 결정
李起白,金奎南,李大吉,李錫熙,南昌熙,張光洙 부산대학교 공과대학 1981 硏究報告 Vol.22 No.-
For the determination of particle size the forward-scatter holography is studied. The methods of hologram construction and image reconstruction using He-Ne laser are described. The conditions of the reconstructed images are compared according to the far field number. With this system, measurement of particle size lessthan 10 μm is not possible and the accuracy is within 5%. To obtain the higher resolving power the improvement of the optical system is needed.
Method for exposing carbon fibers on composite bipolar plates
Lee, Dongyoung,Lim, Jun Woo,Nam, Soohyun,Choi, Ilbeom,Lee, Dai Gil Elsevier 2015 COMPOSITE STRUCTURES -BARKING THEN OXFORD- Vol.134 No.-
<P><B>Abstract</B></P> <P>The carbon/epoxy composite bipolar plate is an ideal substitute for the brittle graphite bipolar plate for proton exchange membrane fuel cells (PEMFCs) and vanadium redox flow batteries (VRFBs) because of its high mechanical properties and easy manufacturing. However, due to the resin-rich area that forms on its surface, the carbon/epoxy composite bipolar plate requires an expanded graphite coating to decrease the areal specific resistance (ASR). The expanded graphite coating not only increases the manufacturing costs but also has very low mechanical properties.</P> <P>In this work, an innovative manufacturing method that exposes carbon fibers on the surface of the carbon/epoxy composite bipolar plate was developed. Soft release films were inserted between the mold and the composite to prevent the formation of a resin-rich area and to expose carbon fibers on the surface of the bipolar plate. The developed method considerably decreased the ASR of the carbon composite bipolar plate without an expanded graphite coating, which satisfied the target established by the Department of Energy (DOE) of United States. The effects of the soft layer on the mechanical and electrical properties of the carbon composite bipolar plate were investigated.</P>
Lee, Kwan Ho,Kim, Byoung Jung,Yoon, Soon Ho,Lee, Dai Gil Informa UK (TaylorFrancis) 2009 Journal of adhesion science and technology Vol.23 No.4
<P>Since metal foils such as aluminum, copper or nickel foils have been used in composite structures for radiation shielding and EMI protection in space environments, high adhesive bonding strength and durability between metal foils and composites under large temperature variations are very important. In this study, the strength of co-cure bonded joint between an aluminum foil and a composite has been investigated, with three different aluminum surface treatments such as standard PAA (Phosphoric Acid Anodization) procedure, abrasion with sandpaper, and carbon black pasting on the metal foils. From the double cantilever beam (DCB) tests, it was found that the interlaminar peel strength with carbon black pasting improved 60% compared to the laminate without any surface treatment. Also it was found that the interlaminar peel strength of the co-cure carbon/epoxy composite-aluminum foil hybrid laminate with the carbon black pasting on the aluminum foil did not decrease after many thermal cycles from 30°C to −196°C.</P>
Electro-mechanical properties of the carbon fabric composites with fibers exposed on the surface
Lee, Dongyoung,Lee, Dai Gil Elsevier 2016 COMPOSITE STRUCTURES -BARKING THEN OXFORD- Vol.140 No.-
<P><B>Abstract</B></P> <P>The carbon/epoxy composite is an ideal substitute for the brittle graphite bipolar plate of the proton exchange membrane fuel cell (PEMFC) because of its high mechanical property and productivity. However, composite bipolar plate suffered from high electrical contact resistance due to the resin-rich area formed on the surface. In order to decrease the contact resistance, “soft layer method”, which could expose bare carbon fibers on the composite surface, was developed. The soft layer method significantly improved the electrical properties of the unidirectional continuous carbon fiber/epoxy composite at the expense of slight degradation of the mechanical properties.</P> <P>In this work, the soft layer method was improved further to develop the carbon fabric/epoxy composite bipolar plate for the PEMFC. Compared to the conventional composite bipolar plates, the developed composite bipolar plates showed superior electrical properties as well as significant increase in the mechanical properties and gas tightness.</P>