• Korean Chemical Engineering Research
• /
• v.59 no.4
• /
• pp.487-492
• /
• 2021

In this study, the electrochemical properties of pitch coated silicon sheets/graphite anode materials were investigated. Using NaCl as a template, silicon sheets were prepared through the stöber method and the magnesiothermic reduction methode. In order to synthesize the anode composite, the silicon sheets and graphite were combined with SDBS. The pitch coated silicon sheets/graphite was synthesized using THF as a solvent for the anode material composite. The physical properties of the prepared anode composites were analysed by XRD, SEM, EDS and TGA. The electrochemical performances of the prepared anode composites were performed by the current charge/discharge, rate performance, cyclic voltammetry and EIS tests in the electrolyte LiPF₆ dissolved solvents (EC:DMC:EMC=1:1:1 vol%). As the silicon composition of silicon sheets/graphite composite material increased, the discharge capacity also increased, but the cycle stability tended to decrease. The anode material of pitch coated silicon sheets/graphite composite (silicon sheets:graphite=3:7 weight ratio) showed the initial discharge capacity of 1228.8 mAh/g and the capacity retention ratio of 77% after 50 cycles. From these results, it was found that the cycle stability of pitch coated silicon sheets/graphite was improved.

• Clinical and Experimental Pediatrics
• /
• v.51 no.3
• /
• pp.267-275
• /
• 2008

Purpose : To determine whether primary snoring could be distinguished from obstructive sleep apnea syndrome (OSAS) by clinical evaluation and symptom scores. Methods : 56 snoring and 20 asymptomatic subjects were recruited and polysomnography was used to confirm that there were 39 OSAS, 17 primary snoring, and 20 control subjects. We evaluated the size of the childrens adenoids and tonsils. Parents completed sleep disordered breathing scale (SDBS) and obstructive sleep apnea 18 (OSA-18) questionnaires for use as symptom scores, as well as an attention deficit hyperactivity disorder rating scale-IV (ADHD RS-IV). Results : There were no differences between primary snoring and OSAS in terms of tonsil and adenoid size, SDBS ($9.4{\pm}4.6\;vs\;10.8{\pm}4.5$), and OSA-18 score ($61.1{\pm}25.1\;vs\;71.2{\pm}8.4$). The patients with OSAS ($15.8{\pm}7.9$) and PS ($22.2{\pm}9.4$) had a higher ADHD RS-IV score than the control subjects ($2.9{\pm}3.3$). There was no difference in the ADHD RS-IV scores of patients with primary snoring and OSAS. Conclusion : We confirmed that clinical evaluation could not distinguish OSAS and primary snoring. In addition, our study suggests that primary snoring as well as OSAS is associated with attention deficit hyperactivity disorder.