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Choi, Jongkwan,Ha, Taejun,Park, Jihye,Lee, Young-Su,Han, Heung Nam,Lee, Joonho,Shim, Jae-Hyeok Elsevier 2019 JOURNAL OF ALLOYS AND COMPOUNDS Vol.784 No.-
<P><B>Abstract</B></P> <P>Mechanochemical synthesis of the Ce<SUB>3</SUB>Al<SUB>11</SUB> powder was performed through a reaction among CeCl<SUB>3</SUB>, AlCl<SUB>3</SUB> and NaH powders. α-Ce<SUB>3</SUB>Al<SUB>11</SUB> particles with an average size of 250 nm were obtained. The catalytic effect of the synthesized Ce<SUB>3</SUB>Al<SUB>11</SUB> on the hydrogen sorption properties of NaAlH<SUB>4</SUB> was investigated. The hydrogen absorption kinetics of NaAlH<SUB>4</SUB> with Ce<SUB>3</SUB>Al<SUB>11</SUB> was significantly enhanced and the hydrogen capacity was improved compared to those properties of NaAlH<SUB>4</SUB> with CeCl<SUB>3</SUB>. This can be attributed to the fine distribution of the Ce<SUB>3</SUB>Al<SUB>11</SUB> catalyst in NaAlH<SUB>4</SUB> during ball milling. Although the volume of the NaAlH<SUB>4</SUB> pellets generally tends to increase during the hydrogen sorption cycles, the volume expansion of the pellet of NaAlH<SUB>4</SUB> with Ce<SUB>3</SUB>Al<SUB>11</SUB> was relatively low with a small pore fraction compared to that of the pellet of NaAlH<SUB>4</SUB> with conventional chloride catalysts such as CeCl<SUB>3</SUB>, TiCl<SUB>3</SUB> and TiCl<SUB>4</SUB>. The use of a nonchloride catalyst appears to provide an effective approach for suppressing the volume expansion of NaAlH<SUB>4</SUB> pellets during the hydrogen sorption cycles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel mechanochemical method for the synthesis of Ce<SUB>3</SUB>Al<SUB>11</SUB> was proposed. </LI> <LI> The catalytic effect of Ce<SUB>3</SUB>Al<SUB>11</SUB> on hydrogen sorption of NaAlH<SUB>4</SUB> was investigated. </LI> <LI> Ce<SUB>3</SUB>Al<SUB>11</SUB> particles were finely distributed in NaAlH<SUB>4</SUB> through ball milling. </LI> <LI> Hydrogen absorption kinetics of NaAlH<SUB>4</SUB> with Ce<SUB>3</SUB>Al<SUB>11</SUB> was significantly enhanced. </LI> <LI> Volume expansion of NaAlH4 pellets was minimized with Ce<SUB>3</SUB>Al<SUB>11</SUB> addition during cycling. </LI> </UL> </P>
Physical Training Gesture Recognition Using Wristwatch Wearable Devices
Taejune Ahn,Jeawon Park,Jaehyun Choi 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.6
Lately, many companies have launched smart watch products with their own strong points, drawing consumers’ attention. A smart watch has changed our life and made it more convenient, offering some different experiences compared to existing smart phones. More importantly, health care using this device has increasingly been the subject of people’s attention and studies. Most of the existing studies have explored mobile devices and multiple sensors recognizing activities related to the routine such as walking, running, and going up and down the stairs. This study has focused on the use in physical training. We made a wearable device with some features of a smart watch, and studied how to make it recognize the activity the user is performing with the built-in accelometer and gyroscope. It is expected to be helpful for the individuals to manage their own exercise systematically and be practical in the health care industry.