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Spent coffee grounds as supporting materials to produce bio-composite PCM with natural waxes
Yoo, Jiwon,Chang, Seong Jin,Wi, Seunghwan,Kim, Sumin Elsevier 2019 CHEMOSPHERE - Vol.235 No.-
<P><B>Abstract</B></P> <P>Novel kinds of bio composite Phase change materials were prepared by the use of bio-wastes. Of the by-products, coffee wastes, which is currently consumed and abandoned as coffee as a drink, was used as the supporting material for PCM. It was found through chemical composition of FTIR of SCBW, SCPW, SCGW and that the coffee wastes were effectively vacuum impregnated into each natural wax. As a result of TGA, the thermal stability of SCBW, SCPW, SCGW and SCNW was checked. In addition, the DSC results were used to determine the heat storage performance of each material. Micro-morphological analysis with FE-SEM showed whether the impregnation was successful. The use of bio-compatible PCM by-products is economical as well as environmentally friendly and is sufficient for building applications in terms of thermal performance compared to other bio-composites.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Composites are made with PCM using coffee grounds as supporting materials. </LI> <LI> Bio-supporting material and bio-PCM are vacuum impregnated to create a complete bio-composites. </LI> <LI> Analyze thermal performance of coffee grounds itself and coffee grounds impregnated with PCM. </LI> <LI> SCGs hardly restricted the phase change behavior of PCM (wax). </LI> <LI> Dynamic heat transfer analysis shows that wax/SCG composite has time lag effect. </LI> </UL> </P>
Chang, Jiwon,Hong, Ji Won,Chae, Hyunsik,Kim, Han Soon,Park, Kyung Mok,Lee, Kyoung In,Yoon, Ho-Sung The Korean Society of Phycology 2013 ALGAE Vol.28 No.1
A freshwater cyanobacterium, Phormidium autumnale KNUA026, was isolated from puddles of icy water in Gyeongsan City, South Korea and its potential as a biofuel feedstock was investigated. Maximal growth was obtained when the culture was incubated at $25^{\circ}C$ and around pH 9.0. The total lipid content of the isolate was approximately 14.0% of dry weight and it was found that strain KNUA026 was able to autotrophically synthesize heptadecane ($C_{17}H_{36}$) which can be directly used as fuel without requiring a transesterification step. As this benthic cyanobacterium was capable of forming thick mats, it could be easily harvested by gravitational settling and this property may reduce the cost of production in commercial applications. Hence, P. autumnale KNUA026 appears to be a promising resource for use in the production of microalgae-based biofuels.
Initial Positioning of a Smart Actuator Using Dual Absolute Encoders
Jiwon Choi,Chang-Hyuk Lee,Young-bong Bang 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10
In order to precisely control motor positions, most motor systems use an encoder as the feedback sensor. In the case of a simple system, an incremental encoder and limit switches are used for initial position setting. However, this system loses the current position data when the power goes down and the final position is changed due to an external force. For this reason, absolute encoders are used in full-fledged systems and to facilitate the best performance, a high-resolution absolute encoder should be directly attached at the output axis. However high-resolution absolute encoders are usually large and expensive, and in many cases, it is structurally difficult to directly install the absolute encoder to the output axis. An alternative to this direct sensing of the output angle is a multiturn absolute encoder, which is attached to the motor shaft. However, the multiturn absolute encoder also loses its position data when the backup battery runs out and an external force is applied. In this paper, we therefore suggest a dual absolute encoder system, in which one absolute encoder is attached to the motor shaft and the other low-resolution absolute encoder is attached to the output shaft of the harmonic drive speed reducer (the output shaft of a smart actuator). The required conditions for the errorless operation of this dual encoder system are derived and verified by simulations and experiments.