Younki Lee
Pohang University of Science and Technology
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Publication
Featured researches published by Younki Lee.
Scientific Reports | 2016
Kun Joong Kim; Byung Hyun Park; Sun Jae Kim; Younki Lee; Hongyeul Bae; Gyeong Man Choi
Miniaturized solid oxide fuel cells (micro-SOFCs) are being extensively studied as a promising alternative to Li batteries for next generation portable power. A new micro-SOFC is designed and fabricated which shows enhanced thermal robustness by employing oxide-based thin-film electrode and porous stainless steel (STS) substrate. To deposit gas-tight thin-film electrolyte on STS, nano-porous composite oxide is proposed and applied as a new contact layer on STS. The micro-SOFC fabricated on composite oxide- STS dual layer substrate shows the peak power density of 560 mW cm−2 at 550 °C and maintains this power density during rapid thermal cycles. This cell may be suitable for portable electronic device that requires high power-density and fast thermal cycling.
Scientific Reports | 2015
Younki Lee; Docheon Ahn; J.-Y. Kim; Young-Hwue Kim; Sung-Woo Cho; Min Ahn; Mann-Ho Cho; M. S. Jung; Duck-Kyun Choi; Min-Cherl Jung; Yabing Qi
We fabricated and characterized the material with Mn (10 at.%: atomic percent) doped In3Sb1Te2 (MIST) using co-sputtering and synchrotron radiation, respectively. The MIST thin film showed phase-changes at 97 and 320°C, with sheet resistances of ~10 kΩsq (amorphous), ~0.2 kΩsq (first phase-change), and ~10 Ωsq (second phase-change). MIST did not exhibit any chemical separation or increased structural instability during either phase-change, as determined with high-resolution x-ray photoelectron spectroscopy. Chemical state changes were only depended for In without concomitant changes of Sb and Te. Apparently, doped Mn atoms can be induced with movement of only In atoms.
Scientific Reports | 2016
Younki Lee; Suyoun Lee; T. Sasaki; Kyu-Sik Kim; Doyeol Ahn; Min-Cherl Jung
We fabricated C-doped (1.5 wt.%) In3Sb1Te2 (CIST) thin films with amorphous phase (a-CIST) using a sputter method. Two electrical-phase-changes at 250 and 275 °C were observed in the sheet resistance measurement. In order to understand the origin of these electrical-phase-changes, all samples were characterized by XRD, TEM, and HRXPS with synchrotron radiation. In a-CIST, only weak Sb-C bonding was observed. In the first electrical-phase-change at 250 °C, strong Sb-C bonding occurred without an accompanying structural/phase change (still amorphous). On the other hand, the second electrical-phase-change at 275 °C was due to the structural/phase change from amorphous to crystalline without a chemical state change.
Solid State Ionics | 2010
Younki Lee; Jong Hoon Joo; Gyeong Man Choi
Solid State Ionics | 2011
Younki Lee; Dong Young Kim; Gyeong Man Choi
Solid State Ionics | 2014
Sun Woong Kim; Younki Lee; Gyeong Man Choi
Journal of Power Sources | 2014
Younki Lee; Young Min Park; Gyeong Man Choi
Fuel Cells | 2015
Hongyeul Bae; Younki Lee; Kun Joong Kim; Gyeong Man Choi
216th ECS Meeting | 2009
Younki Lee; Gyeong Man Choi
Solid State Ionics | 2013
Younki Lee; Jong Hoon Joo; Gyeong Man Choi