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Ex situ aging effect on sulfonated poly(ether ether ketone) membrane:Hydration-dehydration cycling and hydrothermal treatment

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Journal of Energy Chemistry 2022年第7期31卷 583-592,I0014页

作者： Seung-Young choi kyeong Sik Jin Polymer&Materials Chemistry Department of ChemistryLund UniversitySE-22100Sweden Center for Hydrogen·Fuel Cell Research Korea Institute of Science and Technology(KIST)Seoul 02792Republic of Korea Pohang Accelerator Laboratory Pohang University of Science and Technology(POSTECH)PohangKyungbuk 37673Republic of Korea

Prolonged hydrothermal treatment for sulfonated poly(ether ether ketone) membranes induces mechanical degradation and developing hydrophilic-hydrophobic phase separation, simultaneously. The enhanced phase separation provides incremental proton conductivity to the membranes, whereas mechanical degradation drastically reduces device stability. On this basis, we describe here the effects of two different ex situ aging processes on sulfonated poly(ether ether ketone) membranes: hydrationdehydration cycling and prolonged hydrothermal treatment. Both aged membranes exhibited enhanced phase separation under the hydrated conditions, as characterized by small angle X-ray ***, when the aged membranes were dried again, the nanostructure of the membranes aged via the hydration-dehydration cycling was recoverable, whereas that of the membranes aged via prolonged hydrothermal treatment was irreversible. Furthermore, the two differently aged membranes showed clear differences in thermal, mechanical, and electrochemical properties. Finally, we implemented both aged membranes in fuel cell application. The sample aged via hydration-dehydration cycling maintained its improved cell performance, whereas the sample aged via hydrothermal treatment showed drastically reduced cell performance after durability test for 50 h.

关键词： Sulfonated poly(ether ether ketone) Humidity cycle test Ex situ aging Proton exchange membrane Fuel cell

wave-Tide-Surge Coupled Simulation for Typhoon Maemi

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China Ocean Engineering 2013年第2期27卷 141-158页

作者： Byung Ho choi Byung Il Min kyeong Ok Kim Jin Hee Yuk Department of Civil and Environmental Engineering Sungkyunkwan University Marine Environments & Conservation Research Division Korea Institute of Ocean Science & Technology Supercomputing Center Korea Institute of Science and Technology Information

The main task of this study focuses on studying the effect of wave-current interaction on currents, storm surge and wind wave as well as effects of current induced wave refraction and current on waves by using numerical models which consider the bottom boundary layer and sea surface roughness parameter for shallow and smooth bed area around Korean Peninsula. The coupled system （unstructured-mesh SwAN wave and ADCIRC） run on the same unstructured mesh. This identical and homogeneous mesh allows the physics of wave-circulation interactions to be correctly resolved in both models. The unstructured mesh can be applied to a large domain allowing all energy from deep to shallow waters to be seamlessly followed. There is no nesting or overlapping of structured wave meshes, and no interpolation is required. In response to typhoon Maemi （2003）, all model components were validated independently, and shown to provide a faithful representation of the system＇s response to this storm. The waves and storm surge were allowed to develop on the continental shelf and interact with the complex nearshore environment. The resulting modeling system can be used extensively for prediction of the typhoon surge. The result show that it is important to incorporate the wave-current interaction effect into coastal area in the wave-tide-surge coupled model. At the same time, it should consider effects of depth-induced wave breaking, wind field, currents and sea surface elevation in prediction of waves. Specially, we found that：（1） wave radiation stress enhanced the current and surge elevation otherwise wave enhanced nonlinear bottom boundary layer decreased that, （2） wind wave was significantly controlled by sea surface roughness thus we cautiously took the experimental expression. The resulting modeling system can be used for hindcasting （prediction） the wave-tide-surge coupled environments at complex coastline, shallow water and fine sediment area like areas around Korean Peninsula.

关键词： typhoon Maemi finite element model tide-surge-wave coupling

Simulation of Storm Surge and wave Due to Typhoon Isewan(5915)

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China Ocean Engineering 2015年第4期29卷 473-488页

作者： Jin-Hee YUK kyeong Ok KIM Han Soo LEE Byung Ho choi Disaster Management HPC Technology Research Center Korea Institute of Science and Technology Information Marine Radionuclide Research Center Korea Institute of Ocean Science & Technology Graduate School of Science and Engineering Saitama University Department of Civil and Environmental Engineering Sungkyunkwan University

An integrally coupled wave-tide-surge model was developed and then applied to the simulation of the wave-typhoon surge for the typhoon Isewan （typhoon Vera （5915））, which is the strongest typhoon that has struck Japan and caused incalculable damage. An integrally coupled tide-surge-wave model using identical and homogeneous meshes in an unstructured grid system was used to correctly resolve the physics of wave-circulation interaction in both models. All model components were validated independently. The storm surge and wave properties such as the surge height, the significant wave height, wave period and direction were reproduced reasonably under the meteorological forcing, which was reprocessed to be close to the observations. The resulting modeling system can be used extensively for the prediction of the storm surge and waves and the usual barotropic forecast.

关键词： typhoon Isewan storm surge wave tide coupled wave-tide-surge model

Inorganic shell nanostructures to enhance performance and stability of metal nanoparticles in catalytic applications

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Rare Metals 2020年第7期39卷 767-783页

作者： Inhee choi Hyeon kyeong Lee Gyoung woo Lee Jiyull Kim Ji Bong Joo Department of Life Science University of SeoulSeoul 02504Republic of Korea Division of Chemical Engineering Konkuk UniversitySeoul 05029Republic of Korea

In this article,we review the recent progress and our research activity on the synthesis of inorganic shell nanostructures to enhance the catalytic performance and stability of metal nanoparticles in catalytic ***,we introduce general synthetic strategies for the fabrication of inorganic nanoscale shell layers,including template-assisted sol-gel coating,hydrothermal(or solvothermal)synthesis and the self-templating *** also discuss recent examples of metal nanoparticles(NPs)with nanoscale shell layers,namely core-shell,yolk-shell and multiple NPs-embedded nanoscale *** then discuss the performance and stability of metal particles in practical catalytic ***,we conclude with a summary and perspective on the further progress of inorganic nanostructure with nanoscale shell layers for catalytic applications.

关键词： Nanostructures Inorganic shell Metal nanoparticle Stabilization Performance enhancement Catalyst

Effect of the Bottom Topography on Tsunami Propagation in the East (Japan) Sea

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China Ocean Engineering 2008年第2期22卷 277-290页

作者： choi Byung-Ho PELINOVSKY Efim JEON Chul-Kyoo KIM kyeong-Ok Department of Civil and Environmental Engineering Sungkyunkwan University Department of Nonlinear Geophysical Processes Institute of Applied PhysicsNizhny Novgorod 603950 Russia

A study of tsunami events in the East （Japan） Sea using continuous Galerkin finite element model, aiming at reproducing tsunami waves generated by underwater earthquakes in 1983 and 1993 respectively has been performed focusing on the geographic extent of a topographic feature in the East （Japan） Sea. Numerical models can be the proper tools to study the combined effects of realistic topography. Subsequently, using the FEM based two-dimensional model we have simulated the smoothed and flattened topographic effects by removal of Yamato Rise and seamounts for the cases of tthe 1983 Central region earthquake tsunami and the 1993 southwestern Hokkaido earthquake tsunami. The results have shown that there will be higher tsunamis along the eastern coasts of Korea in general except some areas, like Sokcho with removal of topographic highs, thus providing complicated bottom topography of the East （Japan） Sea as effective tsunami energy scattering.

关键词： Yamato Rise 1983 central East (Japan) Sea tsunami 1993 southwestern Hokkaido tsunami

3D engineered tissue models for studying human-specific infectious viral diseases

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Bioactive Materials 2023年第3期21卷 576-594页

作者： kyeong Seob Hwang Eun U Seo Nakwon choi Jongbaeg Kim Hong Nam Kim Brain Science Institute Korea Institute of Science and Technology(KIST)Seoul02792Republic of Korea School of Mechanical Engineering Yonsei UniversitySeoul03722Republic of Korea Yonsei-KIST Convergence Research Institute Yonsei UniversitySeoul03722Republic of Korea Division of Bio-Medical Science&Technology KIST SchoolKorea University of Science and Technology(UST)Seoul02792Republic of Korea KU-KIST Graduate School of Converging Science and Technology Korea UniversitySeoul02841Republic of Korea

Viral infections cause damage to various organ systems by inducing organ-specific symptoms or systemic multi-organ *** on the infection route and virus type,infectious diseases are classified as respiratory,nervous,immune,digestive,or skin *** these infectious diseases can widely spread in the com-munity and their catastrophic effects are severe,identification of their causative agent and mechanisms un-derlying their pathogenesis is an urgent *** infection-associated mechanisms have been studied in two-dimensional(2D)cell culture models and animal models,they have shown limitations in organ-specific or human-associated pathogenesis,and the development of a human-organ-mimetic system is ***,three-dimensional(3D)engineered tissue models,which can present human organ-like physiology in terms of the 3D structure,utilization of human-originated cells,recapitulation of physiological stimuli,and tight cell–cell interactions,were ***,recent studies have shown that these models can recapitulate infection-associated *** this review,we summarized the recent advances in 3D engineered tissue models that mimic organ-specific viral ***,we briefly described the limitations of the current 2D and animal models in recapitulating human-specific viral infection ***,we provided an overview of recently reported viral infection models,focusing particularly on organ-specific infection ***,a future perspective that must be pursued to reconstitute more human-specific infectious diseases is presented.

关键词： 3D engineered tissue model Infectious viral disease Infection route Pathology In vivo-mimicking

Tidal Forecast for Final Closure of Saemangeum Tidal Dike

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China Ocean Engineering 2010年第3期24卷 467-480页

作者： Byung Ho choi Jae wan HA Kwang Oh KO Dae Soo EO kyeong Ok KIM Department of Civil and Environmental Engineering Sungkyunkwan University Hyundai E&C Co. Ltd. Korea Rural Community Corporation Korea Ocean Research & Development Institute

The Saemangeum project includes well-developed tidal flats, two estuaries of the Mankyeong and Dongjin rivers, and a chain of small iskands in the outer area off the dike by reclaiming a surface area of 40100 ha. A long sea dike of 30 km has been constructed in the mid-west area of Korea. This paper describes the construction of tidal dikes focusing on the final closure operation performed in April, 2006 employing intermediate technology. Predictive modelling was also carried out to predict the real-time flow fields during the gradual closure operation of the final stage.

关键词： mathematical modelling dams barrages & reservoirs hydraulics & hydrodynamics sea defence

Development of real-time onion disease monitoring system using image acquisition

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Frontiers of Agricultural Science and Engineering 2018年第4期5卷 469-474页

作者： Du-Han KIM kyeong-Hwan LEE Chang-Hyun choi Tae-Hyun choi Yong-Joo KIM Department of Biosystems Machinery Engineering Chung-Nam National UniversityDaejeon 305-764Republic of Korea Department of Rural and Biosystems Engineering Chonnam National UniversityGwangju 500-757Republic of Korea Department of Bio-Mechatronic Engineering Sungkyunkwan UniversitySuwonGyeonggi 440-746Republic of Korea Sensoreye R&D Solutions Daejeon 302-861Republic of Korea

In this study, real-time disease monitoring was conducted on onion which is the most representative crop in Republic of Korea, using an image acquisition system newly developed for the mobile measurement of phenotype. The purpose of this study was to improve the accuracy of prediction of disease and state variables by processing images acquired from monitoring. The image acquisition system was consisted of two parts, a motorized driving system and a PTZ(pan, tilt and zoom) camera to take images of the plants. The acquired images were processed as follows. Noise was removed through an image filter and RGB(red, green and blue) colors were converted to HSV(hue, saturation and value), which enabled thresholding of areas with different colors and properties for image binarization by comparing the color of onion leaf with ambient areas. Four objects with the most significant browning in the onion leaf to the naked eye were selected as the samples for data acquired. The thresholding method with image processing was found to be superior to the naked eye in identifying accurate disease areas. In addition, it was found that the incidence of disease was different in each disease area ratio. As a result, the use of image acquisition system in image processing analysis will enable more prompt detection of any changes in the onion and monitoring of disease outbreaks during the crop lifecycle.

关键词： imaging acquisition system disease downy mildew onion

An improvement of snow/cloud discrimination from machine learning using geostationary satellite data

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International Journal of Digital Earth 2022年第1期15卷 2355-2375页

作者： Donghyun Jin kyeong-Sang Lee Sungwon choi Noh-Hun Seong Daeseong Jung Suyoung Sim Jongho woo Uujin Jeon Yugyeong Byeon Kyung-Soo Han Division of Earth Environmental System Science (Major of Spatial Information System Engineering) Pukyong National UniversityBusanKorea Korea Institute of Ocean Science and Technology Korea Ocean Satellite CenterBusanKorea BK21 FOUR Project of the School of Integrated Science for Sustainable Earth Environmental Disaster Pukyong National UniversityBusanKorea

Snow and cloud discrimination is a main factor contributing to errors in satellite-based snow *** address the error,satellite-based snow cover performs snow reclassification tests on the cloud pixels of the cloud mask,but the error still *** Learning(ML)has recently been applied to remote sensing to calculate satellite-based meteorological data,and its utility has been *** this study,snow and cloud discrimination errors were analyzed for GK-2A/AMI snow cover,and ML models(Random Forest and Deep Neural Network)were applied to accurately distinguish snow and *** ML-based snow reclassified was integrated with the GK-2A/AMI snow cover through *** used the S-NPP/VIIRS snow cover and ASOS in situ snow observation data,which are satellite-based snow cover and ground truth data,as validation data to evaluate whether the snow/cloud discrimination is *** ML-based integrated snow cover detected 33–53%more snow compared to the GK-2A/AMI snow *** terms of performance,the F1-score and overall accuracy of the GK-2A/AMI snow cover was 73.06%and 89.99%,respectively,and those of the integrated snow cover were 76.78–78.28%and 90.93–91.26%,respectively.

关键词： Geostationary satellite GK-2A/AMI snow cover product snow/cloud discrimination machine learning remote sensing