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Park, Joohyuk,Park, Minjoon,Nam, Gyutae,Kim, Min Gyu,Cho, Jaephil American Chemical Society 2017 NANO LETTERS Vol.17 No.6
<P>Zn-air batteries suffer from the slow kinetics of oxygen reduction reaction (ORR) and/or oxygen evolution reaction (OER). Thus, the bifunctional electrocatalysts are required for the practical application of rechargeable Zn-air batteries. In terms of the catalytic activity and structural stability, pyrochlore oxides (A(2)[B(2-x)A(x)]O7-y) have emerged as promising candidates. However, a limited use of A-site cations (e.g., lead or bismuth cations) of reported pyrochlore catalysts have hampered broad understanding of their catalytic effect and structure. More seriously, the catalytic origin of the pyrochlore structure was not clearly revealed yet. Here, we report the new nano crystalline yttrium ruthenate (Y-2[Ru2-xYx]O7-y) with pyrochlore structure. The prepared pyrochlore oxide demonstrates comparable catalytic activities in both ORR. and OER, compared to that of previously reported metal oxide-based catalysts such as perovskite oxides. Notably, we first find that the catalytic activity of the Y-2[Ru2-xYx]O7-y is associated with the oxidations and corresponding changes of geometric local structures of yttrium and ruthenium ions during electrocatalysis, which were investigated by in situ X-ray absorption spectroscopy (XAS) in real-time. Zn-air batteries using the prepared pyrochlore oxide achieve highly enhanced charge and discharge performance with a stable potential retention for 200 cycles.</P>
Park, Joohyuk,Risch, Marcel,Nam, Gyutae,Park, Minjoon,Shin, Tae Joo,Park, Suhyeon,Kim, Min Gyu,Shao-Horn, Yang,Cho, Jaephil Royal Society of Chemistry 2017 ENERGY AND ENVIRONMENTAL SCIENCE Vol.10 No.1
<P>Oxygen reduction reaction (ORR) or oxygen evolution reaction (OER) electrocatalysts including carbon-, non-precious metal-, metal alloy-, metal oxide-, and carbide/nitride-based materials are of great importance for energy conversion and storage technologies. Among them, metal oxides (<I>e.g.</I>, perovskite and pyrochlore) are known to be promising candidates as electrocatalysts. Nevertheless, the intrinsic catalytic activities of pyrochlore oxides are still poorly understood because of the formation of undesirable phases derived from the synthesis processes. Herein, we present highly pure single crystalline pyrochlore nanoparticles with metallic conduction (Pb2Ru2O6.5) as an efficient bi-functional oxygen electrocatalyst. Notably, it has been experimentally shown that the covalency of Ru-O bonds affects the ORR and OER activities by comparing the X-ray absorption near edge structure (XANES) spectra of the metallic Pb2Ru2O6.5and insulating Sm2Ru2O7for the first time. Moreover, we followed the interatomic distance changes of Ru-O bonds using<I>in situ</I>X-ray absorption spectroscopy (XAS) to investigate the structural stabilities of the pyrochlore catalysts during electrocatalysis. The highly efficient metallic Pb2Ru2O6.5exhibited outstanding bi-functional catalytic activities and stabilities for both ORR and OER in aqueous Zn-air batteries.</P>
( Yunhwan Park ),( Eunyoung Ko ),( Kwangwook Park ),( Changhyun Woo ),( Jaeyoung Kim ),( Sanghun Lee ),( Sanghun Park ),( Yun-a Kim ),( Gyutae Park ),( Jungseok Choi ) 한국축산학회 2022 한국축산학회지 Vol.64 No.1
It is impossible to know the amount of pork primal cut by pig carcass grade which is determined only by carcass weight and backfat thickness in the Korean Pig Carcass System. The aim of this study was to investigate the correlation between the pig carcass grade and the amount of pork primal cut estimated with AutoFom III. A total of 419,321 Landrace, Yorkshire, and Duroc (LYD) pigs were graded with the Korean Pig Carcass Grade System. Amounts of belly, neck, loin, tenderloin, spare ribs, shoulder, and ham were estimated with AutoFom III. Regression equations for seven primal cuts according to each grade were derived. There were significant differences among the three carcass grades due to heteroscedasticity variance (p < 0.0001). Three regression equations were derived from AutoFom III estimation of primal cuts according to carcass grades. The coefficient of determination of the regression equation was 0.941 for grade 1<sup>+</sup>, 0.982 for grade 1, and 0.993 for grade 2. Regression equations obtained from this study are suitable for AutoFom III software, a useful tool for the analysis of each pig carcass grade in the Korean Pig Carcass Grade System. The high reliability of predicting the amount of primal cut with AutoFom III is advantageous for the management of slaughterhouses to optimize their product sorting in Korea.
대규모 언어모델을 활용한 저자원 언어에 대한 Few-Shot 교차 언어 요약 기법
박규태(Gyutae Park),이환희(Hwanhee Lee) 대한전자공학회 2024 대한전자공학회 학술대회 Vol.2024 No.6
Cross-lingual summarization (XLS) aims to generate a summary in a target language different from the source language document. While large language models (LLMs) have shown promising zero-shot XLS performance, their few-shot capabilities on this task remain unexplored, especially for low-resource languages with limited parallel data. In this report, we investigate the few-shot XLS performance of various models, including fine-tuned mT5, GPT-3.5, GPT-4. Our findings highlight the potential of few-shot learning for improving XLS performance and the need for further research in designing LLM architectures and pre-training objectives tailored for this task. We recommend future work to explore more effective few-shot learning strategies and investigate the transfer learning capabilities of LLMs for cross-lingual summarization.
Nam, Gyutae,Park, Joohyuk,Kim, Sun Tai,Shin, Dong-bin,Park, Noejung,Kim, Youngsik,Lee, Jang-Soo,Cho, Jaephil American Chemical Society 2014 NANO LETTERS Vol.14 No.4
<P>Electrocatalysts facilitating oxygen reduction reaction (ORR) are vital components in advanced fuel cells and metal-air batteries. Here we report Ketjenblack incorporated nitrogen-doped carbon sheets derived from gelatin and apply these easily scalable materials as metal-free electrocatalysts for ORR. These carbon nanosheets demonstrate highly comparable catalytic activity for ORR as well as better durability than commercial Vulcan carbon supported Pt catalysts in alkaline media. Physico-chemical characterization and theoretical calculations suggest that proper combination of graphitic and pyridinic nitrogen species with more exposed edge sites effectively facilitates a formation of superoxide, [O<SUB>2(ad)</SUB>]<SUP>−</SUP>, via one-electron transfer, thus increasing catalytic activities for ORR. Our results demonstrate a novel strategy to expose more nitrogen doped edge sites by irregular stacked small sheets in developing better electrocatalysts for Zn-air batteries. These desirable architectures are embodied by an amphiphlilic gelatin mediated compatible synthetic strategy between hydrophobic carbon and aqueous water.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2014/nalefd.2014.14.issue-4/nl404640n/production/images/medium/nl-2013-04640n_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl404640n'>ACS Electronic Supporting Info</A></P>