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Segmented tomographic evaluation of structural degradation of carbon support in proton exchange membrane fuel cells

Journal of Energy Chemistry 2022年第11期31卷 359-367,I0010页

作者： Jung A.Hong Min-Hyoung Jung sung Yong Cho Eun-Byeol park Daehee Yang Young-Hoon Kim Sang-Hyeok Yang Woo-sung Jang jae Hyuck Jang Hyo June Lee sungchul Lee Hu Young Jeong Young-Min Kim Department of Energy Science Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea Fuel Cell Core Parts Development Cell Hyundai Mobis Co.Ltd.Uiwang 16082Republic of Korea Electron Microscopy&Spectroscopy Team Korea Basic Science Institute(KBSI)Daejeon 34133Republic of Korea Graduate School of Semiconductor Materials and Devices Engineering Ulsan National Institute of Science and Technology(UNIST)Ulsan 44919Republic of Korea

The variation of the three-dimensional(3D)structure of the membrane electrode of a fuel cell during proton exchange cycling involves the corrosion/compaction of the carbon *** increasing degradation of the carbon structure continuously reduces the electrocatalytic performance of proton exchange membrane fuel cells(PEM-FCs).This phenomenon can be explained by performing 3D tomographic analysis at the ***,conventional tomographic approaches which present limited experimental feasibility,cannot perform such evaluation and have not provided sufficient structural information with statistical significance thus ***,a reliable methodology is required for the 3D geometrical evaluation of the carbon ***,we propose a segmented tomographic approach which employs pore network analysis that enables the visualization of the geometrical parameters corresponding to the porous carbon structure at a high *** approach can be utilized to evaluate the 3D structural degradation of the porous carbon structure after cycling in terms of local surface area,pore size distribution,and their 3D *** geometrical parameters of the carbon body were demonstrated to be substantially reduced owing to the cycling-induced *** information enables a deeper understanding of the degradation phenomenon of carbon supports and can contribute to the development of stable PEM-FC electrodes.

关键词： Electron tomography Fuel cell Proton exchange membrane Membrane electrode assembly Carbon corrosion

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EXPERIMENTAL ESTIMATION OF A SCALING EXPONENT FOR TIP VORTEX CAVITATION VIA ITS INCEPTION TEST IN FULL-AND MODEL-SHIP

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Journal of Hydrodynamics 2012年第5期24卷 658-667页

作者： LEE Jeung-Hoon JUNG jae-Kwon LEE Kyung-Jun HAN jae-Moon park Hyung-Gil SEO Jong-Soo Samsung Ship Model Basin(SSMB) Marine Research InstituteSamsung Heavy IndustriesScience TownDaejeon 305-380Korea

Tip vortex cavitation noise of marine propeller became primary concems to reduce hazardous environmental impacts from commercial ship or to keep the underwater surveillance of naval ships. The investigations of the tip vortex and its induced noise are normally conducted through the model test in a water cavitation tunnel. However the Reynolds number of model-test is much smaller than that of the full-scale, which subsequently results in the difference of tip vortex cavitation inception. Hence, the scaling law between model- and full-scales needs to be identified prior to the prediction and assessment of propeller noise in full scale. From previous researches, it is generally known that the incipient caivtation number of tip vortex can be represented as a power of the Reynolds number. However, the power exponent for scaling, which is the main focus of this research, has not been clearly studied yet. This paper deals with the estimation of scaling exponent based on tip vortex cavitation inception test in both full- and model-scale ships. Acoustical measurements as well as several kind of signal processing technique for an inception criterion suggest the scaling exponent as 0.30. The scaling value proposed in this study shows slight difference to the one of most recent research. Besides, extrapolation of model-ship noise measurement using the proposed one predicts the full-scale noise measurement with an acceptable discrepancy.

关键词： tip vortex cavitation underwater radiated noise scaling exponent

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Recent Advancement in Modeling Seafloor Dissipative Mechanism in Shallow Water

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China Ocean Engineering 2008年第1期22卷 1-10页

作者： Philip L.-F.LIU Yong sung park School of Civil and Environmental Engineering Cornell University

In this paper, the recent development in modeling seabed dissipative mechanisms in shallow water is reviewed. Specifically, laminar and turbulent boundary layer solutions as well as viscous mud flow solutions under transient waves are presented. These analytical solutions are compared with experimental data for both solitary waves and cnoidal waves. Very goed agreement is ohtained. The Boussinesq equations with boundary layer effects and the muddy seabed effects are also shown.

关键词： seabed dissipative mechardsms boundary layer Boussinesq equations

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Highly flexible and transparent conducting silver nanowire/ZnO composite film for organic solar cells

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Nano Research 2014年第9期7卷 1370-1379页

作者： Myungkwan Song Jong Hyun park Chang Su Kim Dong-Ho Kim Yong-Cheol Kang sung-Ho Jin Won-Yong Jin jae-Wook Kang Surface Technology Division Korea Institute of Materials Science Changwon 641-831 Republic of Korea OLED Development Group LG Display Co. Ltd. Gyeonggi-do 413-811 Republic of Korea Department of Chemistry Pukyong National University 45 Yongso-ro Nam-Gu Busan 608-737 Republic of Korea Department of Chemistry Education Graduate Department of Chemical Materials and Institute for Plastic Information and Energy Materials Pusan National University Busan 609-735 Republic of Korea The Graduate School of Flexible and Printable Electronics Polymer Materials Fusion Research Center Chonbuk National University Jeonju 561-756 Republic of Korea

High efficiency and flexible inverted organic solar cells have been fabricated using solution-processed silver nanowire/zinc oxide composite transparent electrodes. The transparent electrodes showed a low sheet resistance of -13 ff）.sq-1 and high transmittance of -93% as well as superior mechanical flexibility. Power conversion efficiencies of -7.57% and -7.21% were achieved for devices fabricated on glass and plastic substrate, respectively. Moreover, the flexible devices did not show any degradation in their performance even after being folded with a radius of-480 μm.

关键词： silver nanowire flexible transparent conductingelectrode inverted organic solar cell

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Characterization of smooth muscle, enteric nerve, interstitial cells of Cajal, and fibroblast-like cells in the gastric musculature of patients with diabetes mellitus

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World Journal of Gastroenterology 2016年第46期22卷 10131-10139页

作者： Kyung Sik park Kwang Bum Cho Il Seon Hwang jae Hyung park Byung Ik Jang Kyeong Ok Kim sung Woo Jeon Eun Soo Kim Chang Sik park Joong Goo Kwon Department of Internal Medicine Keimyung University School of Medicine Department of Pathology Keimyung University School of Medicine Department of Physiology Keimyung University School of Medicine Department of Internal Medicine Youngnam University College of Medicine Department of Internal Medicine Kyungpook National University School of Medicine Department of Advanced Materials Convergence Korea Institute of Ceramic Engineering and Technology Department of Internal Medicine Catholic University of Daegu School of Medicine

AIM To investigate histologic abnormalities in the gastric smooth muscle of patients with diabetes mellitus(DM).METHODS Full-thickness gastric specimens were obtained from patients undergoing surgery for gastric cancer. H&E stain and Masson's Trichrome stain were performed to assess the degree of fibrosis. Immunohistochemical staining using various antibodies was also performed [antibodies against protein gene product 9.5(PGP9.5), neuronal nitric oxide synthase(n NOS), vasoactive intestinal peptide(VIP), neurokinin-1(NK1) receptor, c-Kit, and platelet-derived growth factor receptor-alpha,(PDGFRα)]. Immunofluorescent staining and evaluation with confocal microscopy were also *** Twenty-six controls and 35 diabetic patients(21 shortduration patients and 14 long-duration patients) were included. There were no significant differences in basic demographics between the two groups except in mean body mass index(BMI)(higher in the DM group). Proportions of moderate-to-severe intercellular fibrosis in the muscle layer were significantly higher in the DM group than in the control group(P < 0.01). On immunohistochemical staining, c-Kit- and PDGFRα-positive immunoreactivity were significantly decreased in the DM group compared with the control group(P < 0.05). There were no statistically significant differences in PGP9.5, n NOS, VIP, and neurokinin 1 expression. On immunofluorescent staining, cellularity of interstitial cells of Cajal(ICC) was observed to decrease with increasing duration of *** Our study suggests that increased intercellular fibrosis, loss of ICC, and loss of fibroblast-like cells are found in the smooth muscle of DM patients. These abnormalities may contribute to changes in gastric motor activity in patients with DM.

关键词： Diabetes mellitus Interstitial cells of Cajal Fibroblast-like cell Gastroparesis Enteric nerve system

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Flexible electronics based on one-dimensional and two-dimensional hybrid nanomaterials

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InfoMat 2020年第1期2卷 33-56页

作者： Jihun park jae Chul Hwang Gon Guk Kim Jang-Ung park Department of Materials Science and Engineering Nano Science Technology InstituteYonsei UniversitySeoulRepublic of Korea Center for Nanomedicine Institute for Basic Science(IBS)Yonsei-IBS InstituteSeoulRepublic of Korea

Research on flexible or wearable electronics has been grown remarkably due to the advent of nanomaterials,such as metal nanowires,graphene,or transition metal *** each nanomaterial has mechanical and electrical characteristics that can be applied into flexible electronics,the limitations of each nanomaterial are also *** order to overcome the limitations of these nanomaterials,research on the hybrid structures of nanomaterials has been extensively *** this study,we introduce the properties of one-dimensional nanomaterials,twodimensional nanomaterials,and their hybrid *** then,we provide information concerning various flexible electronics based on these nanomaterials.

关键词： flexible electronics hybrid nanomaterials one-dimensional nanomaterials two-dimensional nanomaterials wearable electronics

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A Study of BERT-Based Classification Performance of Text-Based Health Counseling Data

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Computer Modeling in Engineering & Sciences 2023年第4期135卷 795-808页

作者： Yeol Woo sung Dae Seung park Cheong Ghil Kim Namseoul University CheonanChungcheongnam-doKorea

The entry into a hyper-connected society increases the generalization of communication using ***,research to analyze big data accumulated in SNS and extractmeaningful information is being conducted in various *** particular,with the recent development of Deep Learning,the performance is rapidly improving by applying it to the field of Natural Language Processing,which is a language understanding technology to obtain accurate contextual *** this paper,when a chatbot system is applied to the healthcare domain for counseling about diseases,the performance of NLP integrated withmachine learning for the accurate classification ofmedical subjects from text-based health counseling data becomes *** the various algorithms,the performance of Bidirectional Encoder Representations from Transformers was compared with other algorithms of CNN,RNN,LSTM,and *** this purpose,the health counseling data of Naver Q&A service were crawled as a *** was used to classify medical subjects according to symptoms and the accuracy of classification results was *** simulation results show that KoBERTmodel performed high performance by more than 5%and close to 18%as large as the smallest.

关键词： BERT NLP deep learning healthcare machine learning

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Aging Analysis Framework of Windows-Based Systems through Differential-Analysis of System Snapshots

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Computers, Materials & Continua 2022年第12期73卷 5091-5102页

作者： Eun-Tae Jang sung Hoon Baek Ki-Woong park SysCore Lab Sejong UniversitySeoul05006Korea Department of Computer System Engineering Jungwon UniversityChungcheongbuk-do28024Korea

When aWindows-based system is used for an exceedingly long time,its performance degrades,and the error occurrence rate tends to *** is generally called system *** investigate the reasons for system aging,various studies have been conducted within the range of the operating system kernel to the user ***,finding an accurate reason for system performance degradation remains challenging research *** this study,system monitoring was conducted by dividing a system into‘before software installation,’‘after software installation,’and‘after software removal.’We confirmed that when a software installed in a system is removed,various system elements,such as storage and memory,are not restored to the level prior to the software ***,we established a hypothesis regarding the performance degradation of a computer system owing to repeated software installation/removal operations,investigated the correlation between system aging and repeated software installation/removal operations,and proposed a system aging analysis framework for analyzing the reason behind system *** the proposed system aging analysis framework,we aim to forcibly age a Windows-based system by repeating the software installation/removal operation by utilizing the system forced aging *** framework identifies the elements affecting system performance through a differential data analysis of the system time-series data extracted by the system performance extraction and system component snapshot ***,the aging analysis framework presented in this study is expected to be effectively utilized as an index for studying system aging.

关键词： System aging virtual machine system analysis

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Recent advances in parametric neuroreceptor mapping with dynamic PET:basic concepts and graphical analyses

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Neuroscience Bulletin 2014年第5期30卷 733-754页

作者： Seongho Seo Su Jin Kim Dong Soo Lee jae sung Lee Department of Nuclear Medicine College of Medicine Department of Brain and Cognitive Sciences College of Natural Sciences institute of Radiation Medicine Medical Research Center Institute of Radiation Medicine Medical Research Center Department of Molecular Medicine and Biopharmaceutical Sciences Graduate School of Convergence Science and Technology Department of Biomedical Sciences College of Medicine Seoul National University

Tracer kinetic modeling in dynamic positron emission tomography （PET） has been widely used to investigate the characteristic distribution patterns or dysfunctions of neuroreceptors in brain diseases. Its practical goal has progressed from regional data quantification to parametric mapping that produces images of kinetic-model parameters by fully exploiting the spatiotemporal information in dynamic PET data. Graphical analysis （GA） is a major parametric mapping technique that is independent on any compartmental model configuration, robust to noise, and computationally efficient. In this paper, we provide an overview of recent advances in the parametric mapping of neuroreceptor binding based on GA methods. The associated basic concepts in tracer kinetic modeling are presented, including commonly-used compartment models and major parameters of interest. Technical details of GA approaches for reversible and irreversible radioligands are described, considering both plasma input and reference tissue input models. Their statistical properties are discussed in view of parametric imaging.

关键词： dynamic positron emission tomography graphical analysis neuroreceptor imaging parametric image tracer kinetic modeling

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α-Lipoic acid protects against cholecystokinin-induced acute pancreatitis in rats

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World Journal of Gastroenterology 2005年第31期11卷 4883-4885页

作者： sung-Joo park Sang-Wan Seo Ok-Sun Choi Cheung-Seog park Department of Pharmacology 1 Hoegi-dong

AIM: α-Lipoic acid (ALA) has been used as an *** aim of this study was to investigate the effect of α-lipoic acid on cholecystokinin (CCK)-octapeptide induced acute pancreatitis in ***: ALA at 1 mg/kg was intra-peritoneally injected, followed by 75 μg/kg CCK-octapeptide injected thrice subcutaneously after 1, 3, and 5 h. This whole procedure was repeated for 5 d. We checked the pancreatic weight/body weight ratio, the secretion of pro-inflammatory cytokines and the levels of lipase,amylase of serum. Repeated CCK octapeptide treatment resulted in typical laboratory and morphological changes of experimentally induced ***: ALA significantly decreased the pancreatic weight/body weight ratio and serum amylase and lipase in CCK octapeptide-induced acute pancreatitis. However,the secretion of IL-1β, IL-6, and TNF-α were comparable in CCK octapeptide-induced acute ***: ALA may have a protective effect against CCK octapeptide-induced acute pancreatitis.

关键词： α-Upoic add AoJte pancreatitis Proinflammatory cytokines Cholecystokinin

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