저온 고체산화물 연료전지를 위한 니켈기반 박막 연료극의 제작 및 전기화학적 특성 분석

학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2017. 2. 차석원.In this study, various types of pure nickel (Ni) and Ni-based cermet anodes were fabricated onto nanoporous substrates and applied to thin-film solid oxide fuel cells (SOFCs) for low temperature operation. Sputtering technique was utilized to fabricate the experimental fuel cells by sequential deposition of anodes, electrolytes, and cathodes on the substrate materials. Depending on its nanostructure, the pure Ni anodes exhibited comparable performance to the optimized platinum (Pt) anode at 500 ℃. However, compared to the optimized Pt anode cell, the polarization resistances of the pure Ni anode cells were significantly larger. In order to reduce the polarization resistance of Ni-based anodes and obtain better electrochemical characteristics, a Ni/Ni-based cermet bilayer anode structure was introduced. For optimization of the Ni-based cermet, five types of Ni-yttria stabilized zirconia (Ni-YSZ) composite films were fabricated via co-sputtering method and electrochemically investigated. As a result, a Ni-YSZ film fabricated by co-sputtering method with 50 W DC and 100 W RF powers showed the lowest polarization resistance. Therefore, this Ni-YSZ film was selected as Ni-YSZ layer of the Ni/Ni-YSZ bilayer anode. For Ni layer, a 150 nm-thick pure Ni anode, which showed the best performance among the fabricated pure Ni films, was employed. This 150 nm-thick pure Ni film was sputtered with DC 200 W under 5 mTorr argon (Ar) atmosphere. On the nanoporous substrate, the Ni-based bilayer anode, YSZ electrolyte, and Pt cathode was sequentially deposited to fabricate a full cell. At 500 ℃, the peak power density of the full cell was about 37 % higher (282 mW/cm2) than that of the optimized Pt anode cell (205 mW/cm2). Moreover, the Ni-based bilayer anode cell exhibited much lower ohmic and polarization resistances compared to other fabricated cells. This shows the acceptability of non-noble metal anode for low-temperature SOFCs.Chapter 1. Introduction 1 1.1. Study Background 1 1.1.1. Fuel Cells. 1 1.1.2. Solid Oxide Fuel Cells. 3 1.1.3. Thin-film SOFCs 6 1.2. Purpose of Research. 9 Chapter 2. Experimental Details 12 2.1. Fabrication of Experimental Cells. 12 2.2. Fabrication of Various Anodes 13 2.2.1. Fabrication of the Optimized Pt Anode 13 2.2.2. Fabrication of Pure Ni Anodes. 13 2.2.3. Fabrication of Ni-YSZ Cermet Anodes. 16 2.2.4. Fabrication of a Ni/Ni-YSZ Bilayer Anode. 17 2.3. Film and Cell Characterization. 18 Chapter 3. Result and Discussion 19 3.1. Investigating Various Pure Ni Anode Structures. 19 3.1.1. Porous Ni Anodes. 19 3.1.2. Dense Ni Anodes. 24 3.2. Investigating Various Ni-YSZ Anodes. 29 3.3. Ni/Ni-YSZ Bilayer Anodes 34 Chapter 4. Conclusion 38 Bibliography 40 국문초록 50Maste

Walking Aided Apparatus of lifting type

본 발명이 제안하는 리프트식 보행보조장치은 양끝단이 지면에 맞닿도록 양쪽 측면에 각각 구비된 지주프레임과, 소정의 폭 간격으로 상기 지주프레임을 연결, 결속하는 링크프레임 이외에, 상기 지주프레임의 상단 내측에 구비되며, 지면으로부터 수직 및 수평 방향으로 슬라이딩과 동시에 회동가능한 리프트 바를 포함하는 것으로, 수동에서부터 전동식까지 포함한다.본 발명의 실시예에 따르면, 수직은 물론, 수평 방향으로 동시에 슬라이딩과 회동을 병행할 수 있도록 구성된 리프트 바로부터 거동이 불편한 사용자가 혼자 보행을 위한 이동은 물론, 의자나 소파 등으로부터 앉거나 일어서는 일상생활 중의 동작까지 보조함으로써, 별다른 도움없이 독립적인 활동을 보장할 수 있는 기술적 효과를 얻는다