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폐쇄성 수면무호흡증 환자에서 구개수구개인두성형술 후 폐용적의 변화
강기석,장백암,백승훈,김은석,강정한 대한이비인후과학회 2002 대한이비인후과학회지 두경부외과학 Vol.45 No.1
Background and Objectives:The objective of this research was to study the change of lung volume after uvulopalatoph-aryngoplasty (UPPP) in obstructive sleep apnea (OSA) patients. Materials and Methoid:Eight OSA patients were pa-rticipated in this study. These patients were treated with UPPP at Seoul adventist hospital. Vital capacity (VC), inspiratory capacity (IC), expiratory residual volume (ERV) and FEV1, FEV1/FVC, FEV25-75% were determined by standard spirometry at the preoperative, at 3 postoperative days and 1 postoperative month. Results:Vital capacity (VC) was significantly larger at 3 post-operative days (3.58± 0.87 L, mean± SD) than those at pre-operative (3.12± 0.69 L, mean± SD)OSA (p=0.047). FEV1 (L) was larger at 3 post-operative days (2.91± 0.76 L, mean± SD) than those at pre-operative (2.68± 0.85 L, mean± SD), but was not significantly correlated statically (p=0.249). Conclusion:We found significant core-lation betwen preopeative and postoperative VC, IC. (Korean J Otolaryngol 2002;45:51-5)
High energy density of the lithium-rich layered oxides (LLO) and new lithium diffusion model for LLO
강기석 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
Cobalt-free layered lithium-rich nickel manganese oxides, Li[Li<sub>x</sub>Ni<sub>y</sub> Mn<sub>1-x-y</sub>]O<sub>2</sub>, are one of the promising positive electrode materials for lithium rechargeable batteries because of their high energy density and low materials cost. However, substantial voltage decay is inevitable upon electrochemical cycling, which makes this class of materials less practical. In my talk, we demonstrate that the voltage decay of the electrode is correlated to Mn<sup>4+</sup>/Mn<sup>3+</sup> redox activation and subsequent cation disordering, which can be remarkably suppressed via simple compositional tuning to induce the formation of Ni<sup>3+</sup> in the pristine material. By implementing our new strategy, the Mn<sup>4+</sup>/Mn<sup>3+</sup> reduction is subdued by an alternative redox reaction involving the use of pristine Ni<sup>3+</sup> as a redox buffer, which has been designed to be widened from Ni<sup>3+</sup>/Ni<sup>4+</sup> to Ni<sup>2+</sup>/Ni<sup>4+</sup>, without compensation for the capacity in principle. Negligible change in the voltage profile of modified LLNMO is observed upon extended cycling, and manganese migration into the lithium layer is significantly suppressed.
강기석 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1
The use of biologically occurring redox centers holds a great potential in designing sustainable energy storage systems. Yet, to become practically feasible, it is critical to explore optimization strategies of biological redox compounds, along with in-depth studies regarding their underlying energy storage mechanisms. In this talk, a molecular simplification strategy combined with nano architecture is demonstrated to tailor the redox unit of pteridine derivatives in practical rechargeable batteries, which are essential components of ubiquitous electron transfer proteins in nature. It is applied to pteridine systems of alloxazinic structure in lithium/sodium rechargeable batteries, and their reversible tautomerism is unveiled during energy storage. Through the molecular tailoring, the pteridine electrodes can show outstanding performance, delivering 533 Wh kg<sup>-1</sup> within 1 hour and 348 Wh kg<sup>-1</sup> within 1 minute, as well as high cyclability retaining 96% of the initial capacity after 500 cycles at 10 Ag<sup>-1</sup>. Our strategy combined with experimental and theoretical studies enriches the pool of sustainable energy materials and suggests guidance for the rational design for organic redox centers.