High Electrochemical Activity of Bi₂O₃-based Composite SOFC Cathodes

Jung, Woo Chul,Chang, Yun-Jie,Fung, Kuan-Zong,Haile, Sossina The Korean Ceramic Society 2014 한국세라믹학회지 Vol.51 No.4

Due to high ionic conductivity and favorable oxygen electrocatalysis, doped $Bi_2O_3$ systems are promising candidates as solid oxide fuel cell cathode materials. Recently, several researchers reported reasonably low cathode polarization resistance by adding electronically conducting materials such as (La,Sr)$MnO_3$ (LSM) or Ag to doped $Bi_2O_3$ compositions. Despite extensive research efforts toward maximizing cathode performance, however, the inherent catalytic activity and electrochemical reaction pathways of these promising materials remain largely unknown. Here, we prepare a symmetrical structure with identically sized $Y_{0.5}Bi_{1.5}O_3$/LSM composite electrodes on both sides of a YSZ electrolyte substrate. AC impedance spectroscopy (ACIS) measurements of electrochemical cells with varied cathode compositions reveal the important role of bismuth oxide phase for oxygen electrocatalysis. These observations aid in directing future research into the reaction pathways and the site-specific electrocatalytic activity as well as giving improved guidance for optimizing SOFC cathode structures with doped $Bi_2O_3$ compositions.

Robust nanostructures with exceptionally high electrochemical reaction activity for high temperature fuel cell electrodes

Jung, WooChul,Gu, Kevin L.,Choi, Yoonseok,Haile, Sossina M. The Royal Society of Chemistry 2014 Energy & environmental science Vol.7 No.5

<P>Metal nanoparticles are of significant importance for chemical and electrochemical transformations due to their high surface-to-volume ratio and possible unique catalytic properties. However, the poor thermal stability of nano-sized particles typically limits their use to low temperature conditions (<500 °C). Furthermore, for electrocatalytic applications they must be placed in simultaneous contact with percolating ionic and electronic current transport pathways. These factors have limited the application of nanoscale metal catalysts (diameter <5 nm) in solid oxide fuel cell (SOFC) electrodes. Here we overcome these challenges of thermal stability and microstructural design by stabilizing metal nanoparticles on a scaffold of Sm<SUB>0.2</SUB>Ce<SUB>0.8</SUB>O<SUB>2−<I>δ</I></SUB> (SDC) films with highly porous and vertically-oriented morphology, where the oxide serves as a support, as a mixed conducting transport layer for fuel electro-oxidation reactions, and as an inherently active partner in catalysis. The SDC films are grown on single crystal YSZ electrolyte substrates by means of pulsed-laser deposition, and the metals (11 μg cm<SUP>−2</SUP> of Pt, Ni, Co, or Pd) are subsequently applied by D.C. sputtering. The resulting structures are examined by TEM, SIMS, and electron diffraction, and metal nanoparticles are found to be stabilized on the porous SDC structure even after exposure to 650 °C under humidified H<SUB>2</SUB> for 100 h. A.C. impedance spectroscopy of the metal-decorated porous SDC films reveals exceptionally high electrochemical reaction activity toward hydrogen electro-oxidation, as well as, in the particular case of Pt, coking resistance when CH<SUB>4</SUB> is supplied as the fuel. The implications of these results for scalable and high performance thin-film-based SOFCs at reduced operating temperature are discussed.</P> <P>Graphic Abstract</P><P>Combination of nanostructured ceria and nanoscale metal particles leads to unprecedented activity for hydrogen and methane electro-oxidation along with excellent morphological stability. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3ee43546f'> </P>

Investigating Performances of Takeover Activities using Google Trend Search Volume Index

Kyounghun Bae,Hail Jung,Daejin Kim 한국재무학회 2018 한국재무학회 학술대회 Vol.2018 No.05

Ways to measuring public attention are important questions, and many researchers use indirect measures to capture investors’ attention such as trading volume (Hou et al., 2008), extreme returns (Barber and Odean, 2008), and news and headlines (Yuan, 2008). On this research, we use Google search volume index which provides a direct measure to detect people’s interest. Using M&A data of the United States, we investigate the causality over search volume query changes on takeover returns. We find abnormal trends in Google search volume index such as volume reaching the spike before the mergers announcements. We present that earlier search volume hits the spike, more outperforming on both acquirer and target sides. We further believe that our research can contribute to the academia as a novel method to detect possible information leakage problem.

Climate change risk and the value of cash holdings

Sanghak Choi,Hail Jung,Daejin Kim 한국재무학회 2021 한국재무학회 학술대회 Vol.2021 No.11

In this paper, we investigate the effects of the firm-level climate change risk on the marginal value of corporate cash holdings. The underlying idea is that climate change risks would induce firms to increase their demand for capital, which may also lead to an increase in the value of the cash holdings. As the climate change risk is an uncertainty for firms, investors would also positively evaluate the firm’s excess cash. A regression analysis finds a positive association between the firm-level climate change risk and the value of cash holdings. Furthermore, we also test how the green swan and financial constraint level affect the relationship. Subsample analysis shows that the market positively values the cash holdings of firms that are more sensitive to climate change and that are more financially constrained. Various robustness tests confirm that the baseline regression results are not necessarily driven by endogeneity.

Antioxidant activity and total phenolic contents of eggplant core collection

Nayoung Ro,Mesfin Haile Kebede,Bitsam Kim,Gyu-Taek Cho,Munsup Yoon,Jungro Lee,Yoon-Jung Lee 한국식품영양과학회 2022 한국식품영양과학회 학술대회발표집 Vol.2022 No.10

Electrochemically modified, robust solid oxide fuel cell anode for direct-hydrocarbon utilization

Choi, Y.,Brown, E.C.,Haile, S.M.,Jung, W. Elsevier 2016 Nano energy Vol.23 No.-

<P>A main advantage of solid oxide fuel cells (SOFCs) operating at a high temperature ( > 650 degrees C) is the flexibility of the fuel they use, specifically as they offer the possibility to utilize methane (natural gas). Unfortunately, however, the state-of-the-art SOFC anodes, composed of a nickel and an anionically conducting oxide such as yttria-stabilized zirconia (YSZ), are associated with Ni-catalyzed carbon deposition and the ensuing degradation of the anode performance. Here, we address these issues through the application of a simple, scalable, cost-effective ceramic coating method known as cathodic electrochemical deposition (CELD). Samaria-doped CeO2 (SDC) was chosen as the coating material due to its high chemical stability against carbon formation, high electronic and ionic conductivities, and favorable electrocatalytic activity toward fuel oxidation reaction. Nanostructured SDC layers with a high specific surface area were successfully coated onto Ni surfaces via CELD. The physical and chemical attributes of each coating were characterized by a range of analysis tools, in this case SEM, TEM, XRD, EDS, ICP-MS and Raman spectroscopy. An analysis of the AC impedance spectroscopy (ACIS) of Ni-patterned YSZ symmetric cells (anodelelectrolytelanode) with SDC coatings revealed significantly enhanced electrode activity toward fuel oxidation and coking stability under dry or wet methane fuel at 650 degrees C. These results suggest that the Ni-surface modification via CELD can be a feasible solution for the direct use of hydrocarbon fuels in SOFCs. (C) 2016 Elsevier Ltd. All rights reserved.</P>

충청 지역 산업단지 인근 취약 농경지에 대한 중금속 오염도 평가

홍영규(Youngkyu Hong),김진욱(Jinwook Kim),정하일(Hail Jung),김성철(Sungchul Kim) 한국토양비료학회 2022 한국토양비료학회 학술발표회 초록집 Vol.2022 No.10

지수화 방법을 활용한 산업단지 인근 농경지 토양 중금속 오염도 평가 및 토양질 평가

홍영규(Youngkyu Hong),김진욱(Jinwook Kim),정하일(Hail Jung),김성철(Sungchul Kim) 한국토양비료학회 2021 한국토양비료학회 학술발표회 초록집 Vol.2021 No.11

안전 농산물 생산을 위해서는 토양 관리가 중요하며 특히 산업단지 인근 취약 농경지의 경우 주변 환경 특성에 따라 복합적인 중금속 오염이 발생할 수 있다. 따라서, 본 연구의 목적은 지역별 차이에 따른 복합 중금속 오염의 오염도를 지수화 모델을 사용하여 평가하며 또한 토양질 모델을 사용하여 중금속 오염에 따른 토양질의 변화를 분석하는 것이다. 토양 시료는 10개의 충청북도 지역 산업단지 인근 농경지에서 총 100점의 표토 시료를 채취하였으며 중금속 분석은 총함량 분석법으로 분석하였다. 중금속 분석 결과 토양 오염 우려 기준을 초과하는 농경지 토양은 없었으며 각 중금속별 검출 농도는 다음과 같다. 비소 (As)의 경우 평균 5.15 mg kg<SUP>-1</SUP> 으로 검출 범위는 0.30~15.8 mg kg<SUP>-1</SUP> 이였으며 카드뮴 (Cd)의 경우 평균 0.40 mg kg<SUP>-1</SUP>, 검출 범위는 0.02~1.46 mg kg<SUP>-1</SUP> 수준이었다. 구리 (Cu), 니켈 (Ni), 납 (Pb), 아연 (Zn)의 평균 농도는 각각 11.1 (0.00~48.9), 11.4 (0.45~42.8), 14.7 (0.68~145.9), 85.4 (4.06~240.1) mg kg<SUP>-1</SUP> 이었다. 중금속 결과를 지수화 모델을 활용하여 평가한 결과 연구 대상 지역 농경지의 지수화 범위는 0.02~0.24 로 충주시에 위치한 산업 단지 인근 농경지의 지수값이 0.24로 가장 높았으며 제천시에 위치한 산업단지 인근 농경지 토양이 0.02로 가장 낮은 지수값을 나타내었다. 토양질을 평가하기 위해 pH, EC, 유기물, 유효인산, CEC를 지수화 모델에 적용하여 평가하였다. 각 인자를 산출하여 종합적으로 평가한 결과 제천시 산업단지 인근 농경지가 가장 높은 3.20으로 나타났으며, 청주시 산업단지 인근 농경지에서 0.69로 가장 낮게 나타났다. 지수화 모델을 적용한 토양 내 중금속 오염도 평가 방법은 복합 중금속에 대한 오염도 평가뿐 아니라 오염토양에 대한 복원 시 우선 순위를 결정할 수 있는 방법으로 활용 가능하다. 또한 중금속 오염에 따른 토양질 평가를 통해 오염에 따른 토양의 특성 변화를 예측하여 향후 토양 관리를 위한 기초 자료로 활용이 가능할 것으로 사료된다.

Association of variations in TPH1 and HTR2B with gestational weight gain and measures of obesity.

Kwak, Soo Heon,Park, Byoung Lae,Kim, Hail,German, Michael S,Go, Min Jin,Jung, Hye Seung,Koo, Bo Kyong,Cho, Young Min,Choi, Sung Hee,Cho, Yoon Shin,Shin, Hyoung Doo,Jang, Hak C,Park, Kyong Soo NAASO, the Obesity Society 2012 Obesity Vol.20 No.1

<P>Serotonin is involved in appetite regulation and energy homeostasis. Recently, it has been reported that 5-hydroxytryptamine receptor 2B (Htr2b) and tryptophan hydroxylase 1 (Tph1) play major role in β-cell proliferation in mouse during pregnancy. We investigated the genetic association of HTR2B and TPH1 with risk of gestational diabetes mellitus (GDM) and measures of obesity, in 869 Korean GDM women and carefully selected 632 nondiabetic control subjects. Six single-nucleotide polymorphisms (SNPs) in HTR2B and ten SNPs in TPH1 were selected for genotyping according to their tagging status. Genetic variants in HTR2B and TPH1 were not associated with the risk of GDM. In GDM women, SNPs of TPH1 were significantly associated with weight gain during pregnancy. In nondiabetic controls, SNPs of TPH1 were associated with waist circumference and BMI. We also found that a variant of TPH1 (rs623580) was associated with BMI in a genome-wide association study comprised of 8,842 subjects. Although genetic variants in HTR2B and TPH1 were not associated with risk of GDM, we found significant association of these variants with measures of obesity. However, further replication studies in a different population are required to confirm our findings.</P>

The Industrial Application of Artificial Intelligence-based Optical Character Recognition in Modern Manufacturing Innovations

Qing Tang,YoungSeok Lee(이영석),Hail Jung(정하일),Taehyun Yoon(윤태현) 한국통신학회 2023 한국통신학회 학술대회논문집 Vol.2023 No.11