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Impact loads generated by tandem cavitation bubble on solid wall

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Journal of Hydrodynamics 2022年第3期34卷 467-482页

作者： Nyo Me Thet Naing Jaehyun park seung-Ho Hyun Rho-Taek Jung School of Naval Architecture and Ocean Engineering University of UlsanUlsanKorea School of Electrical Engineering University of UlsanUlsanKorea Foundation for Industry Cooperation University of UlsanUlsanKorea

Experiments on two cavitation bubbles,which are generated at the same instant,with three different sizes near solid wall are conducted and their impulses on the boundary are registered by polyvinylidene fluoride(PVDF)*** to being near the boundary,bubble interactions and deformed features are in contrast with those in infinite fluid *** this paper,five morphologies of bubble deformation during growth and collapse phases are observed by high-speed *** profiles are strongly influenced by inter-bubble distance(η),stand-off distance from boundary(γ),and bubble size *** of photographs coupled with sensor measurements enabled qualitative investigation of two bubble interactions on the *** sensor data acquisition,it is confirmed that lower bigger bubble with upper smaller bubble configuration produces highest impulses on the boundary compared with other vertical arrangements of the tandem cavitation bubble employed in this study.

关键词： Two bubbles spark-generated bubble impulse polyvinylidene fluoride(PVDF)

A Regional Economy's Resistance to the COVID-19 Shock: Sales Revenues of Micro-, Small-, and Medium-Sized Enterprises in South Korea

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International Journal of Disaster Risk Science 2022年第2期13卷 190-198页

作者： Seong-Jin Lee Joong-Hoo park seung-Min Cha Donghyun Kim Department of Public Policy and Management.Pusan National University Busan 46241South Korea Department of Urban Planning and Engineering Pusan National UniversityBusan 46241South Korea

The coronavirus disease 2019(COVID-19) is a global pandemic that has heavily impacted not only the health sector, but also the economic sector in *** countries have projected a negative economic impact, and the effect on micro-, small-, and medium-sized enterprises(MSMEs) is predicted to be significantly *** study estimated the regional resistance of MSME sales revenues and identified the regional economic factors that affect resistance by analyzing South Korea, a country with one of the lowest economic impact projections from COVID-19. Resistance was estimated by comparing sales revenues and changes in resistance observed during the early COVID-19 period to those recorded in the same weeks(weeks 6 to 9) of 2019. The factors that affect regional resistance were determined by conducting robust regression and spatial regression analyses. The results show that the number of confirmed COVID-19 cases, a direct risk factor, is negatively related to regional resilience, while diversity is positively related to regional resistance. To improve the regional resistance against uncertain events, this study recommends increased diversity among regional industrial structures to reduce the duration of the early shock of an unexpected adverse event.

关键词： COVID-19 Economic resistance MSMEs South Korea

Evaluation of early-age strains and stresses in roller-compacted concrete pavement

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Journal of Traffic and Transportation Engineering(English Edition) 2022年第1期9卷 93-105页

作者： Tetsya Sok Young Kyu Kim Jun Young park seung Woo Lee Public Infrastructure Department Ministry of Public Works and TransportPhnom Penh 12100Cambodia Institute for Disaster Prevention Gangneung-Wonju National UniversityGangneung-si 25457South Korea Korea Expressway Research Institute Korea Expressway CorporationHwaseong-si 18489South Korea Civil Engineering Department Gangneung-Wonju National UniversityGangneung-si 25457South Korea

In the structural design of a roller-compacted concrete pavement(RCCP), it is crucial to estimate strain and stress developments in the RCCP slab realistically. Since the RCCP mix uses less cement and lower amount of water, shrinkage strain and concrete temperature during the hardening stage are expected to be reduced as compared to those of conventional concrete mixture, resulting in a reduction of the concrete early-age deformation and stress developments in the RCCP slab. In this paper, early-age concrete strain and stress developments in RCCP slab subjected to environmental loads were evaluated. A full-scale test section of RCCP under real climatic conditions was monitored. The early-age total strains,stress-independent strains, shrinkage strains, and coefficient of thermal expansion(CTE) of the RCCP were measured and analyzed. Using the results of measured strains, in-situ CTE and shrinkage strain, and temperature, the early-age concrete stress development is computed by incorporating a viscoelastic property of the early-age concrete. The results revealed that the shrinkage strain of the RCCP is quite low as compared to that of conventional concrete. The early-age stress developments in the RCCP slab are strongly governed by the thermal-induced stresses. Shrinkage-induced stresses were quite small and might be negligible in a preliminary estimation of early-age stress developments in the RCCP slab.

关键词： Road engineering Roller-compacted concrete pavement Concrete strain Concrete stress Shrinkage strain Environmental loads

Carbon-Coated Three-Dimensional MXene/Iron Selenide Ball with Core–Shell Structure for High-Performance Potassium-Ion Batteries

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Nano-Micro Letters 2022年第1期14卷 278-294页

作者： Su Hyun Yang Yun Jae Lee Heemin Kang seung-Keun park Yun Chan Kang Department of Materials Science and Engineering Korea UniversityAnam-DongSeongbuk-GuSeoul 136-713Republic of Korea Department of Advanced Materials Engineering Chung-Ang University4726 Seodong-daeroDaedeok-myeonAnseong-siGyeonggi-do 17546Republic of Korea

Two-dimensional(2D)MXenes are promising as electrode materials for energy storage,owing to their high electronic conductivity and low diffusion ***,similar to most 2D materials,MXene nanosheets easily restack during the electrode preparation,which degrades the electrochemical performance of MXene-based materials.A novel synthetic strategy is proposed for converting MXene into restacking-inhibited three-dimensional(3D)balls coated with iron selenides and *** strategy involves the preparation of Fe_(2)O_(3)@carbon/MXene microspheres via a facile ultrasonic spray pyrolysis and subsequent selenization *** 3D structuring effectively prevents interlayer restacking,increases the surface area,and accelerates ion transport,while maintaining the attractive properties of ***,combining iron selenides and carbon with 3D MXene balls offers many more sites for ion storage and enhances the structural robustness of the composite *** resultant 3D structured microspheres exhibit a high reversible capacity of 410 mAh g^(−1) after 200 cycles at 0.1 A g^(−1) in potassium-ion batteries,corresponding to the capacity retention of 97% as calculated based on 100 *** at a high current density of 5.0 A g^(−1),the composite exhibits a discharge capacity of 169 mAh g^(−1).

关键词： MXene Spray pyrolysis Iron selenide Potassium-ion batteries 3D structures

Nanoscale visualization of hot carrier generation and transfer at non-noble metal and oxide interface

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Journal of Materials Science & Technology 2022年第3期98卷 151-159页

作者： Ranveer Singh Qadeer Akbar Sial seung-ik Han Sanghee Nah Ji-Yong park Hyungtak Seo Department of Materials Science and Engineering Ajou UniversitySuwon16499Republic of Korea Department of Energy Systems Research Ajou UniversitySuwon16499Republic of Korea Seoul Center Korea Basic Science InstituteSeoul02841Republic of Korea Department of Physics Ajou UniversitySuwon16499Republic of Korea

The conversion efficiency of energy-harvesting devices can be increased by utilizing hot-carriers(HCs).However,due to ultrafast carrier-carrier scattering and the lack of carrier injection dynamics,HC-based devices have low *** the present work,we report the effective utilization of HCs at the nanoscale and their transfer dynamics from a non-noble metal to a metal oxide interface by means of real-space photocurrent mapping by using local probe techniques and conducting femtosecond transient absorption(TA)*** photocurrent maps obtained under white light unambiguously show that the HCs are injected into the metal oxide layer from the TiN layer,as also confirmed by conductive atomic force *** addition,the increased photocurrent in the bilayer structure indicates the injection of HCs from both layers due to the broadband absorption efficiency of TiN layer,passivation of the surface states by the top TiN layer,and smaller barrier height of the ***,electrostatic force microscopy and Kelvin probe force microscopy provide direct evidence of charge injection from TiN to the MoO_(x)film at the *** TA absorption spectra show a strong photo-bleaching signal over wide spectral range and ultrafast decaying behavior at the picosecond time scale,which indicate efficient electron transfer from TiN to MoO_(x).Thus,our simple and effective approach can facilitate HC collection under white light,thereby achieving high conversion efficiency for optoelectronic devices.

关键词： Non-noble metal Hot carrier Real-space photocurrent mapping Local-probe force microscopy

Absorption-Dominant mmWave EMI Shielding Films with Ultralow Reflection using Ferromagnetic Resonance Frequency Tunable M-Type Ferrites

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Nano-Micro Letters 2023年第6期15卷 1-23页

作者： Horim Lee seung Han Ryu Suk Jin Kwon Jae Ryung Choi Sang‑bok Lee Byeongjin park Composites Research Division Korea Institute of Materials Science797 ChangwondaeroSeongsan‑GuChangwonGyeongsangnam‑Do 51508Republic of Korea

Although there is a high demand for absorption-dominant electromagnetic interference(EMI) shielding materials for 5G millimeter-wave(mmWave) frequencies, most current shielding materials are based on reflection-dominant conductive materials. While there are few absorption-dominant shielding materials proposed with magnetic materials, their working frequencies are usually limited to under 30 GHz. In this study, a novel multi-band absorption-dominant EMI shielding film with M-type strontium ferrites and a conductive grid is proposed. This film shows ultralow EMI reflection of less than 5% in multiple mmWave frequency bands with sub-millimeter thicknesses, while shielding more than 99.9% of EMI. The ultralow reflection frequency bands are controllable by tuning the ferromagnetic resonance frequency of M-type strontium ferrites and composite layer geometries. Two examples of shielding films with ultralow reflection frequencies, one for 39 and 52 GHz 5G telecommunication bands and the other for 60 and 77 GHz autonomous radar bands, are presented. The remarkably low reflectance and thinness of the proposed films provide an important advancement toward the commercialization of EMI shielding materials for 5G mmWave applications.

关键词： 5G communication MmWave EMI shielding M-type ferrites

Neotectonic transpressional intraplate deformation in eastern Eurasia: Insights from active fault systems in the southeastern Korean Peninsula

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Geoscience Frontiers 2023年第4期14卷 123-136页

作者： Namgwon Kim seung-Ik park Chang Soo Cho Youngbeom Cheon Alexander L.Peace Department of Geology Kyungpook National UniversityDaegu 41566Republic of Korea Earthquake Research Center Korea Institute of Geosciences and Mineral ResourcesDaejeon 34132Republic of Korea Active Tectonics Research Center Korea Institute of Geosciences and Mineral ResourcesDaejeon 34132Republic of Korea School of Earth Environment and SocietyMcMaster UniversityHamiltonON L8S 4K1Canada

Transpression occurs in response to oblique convergence across a deformation zone in intraplate regions and plate *** Korean Peninsula is located at an intraplate region of the eastern Eurasian Plate and has been deformed under the ENE–WSW maximum horizontal compression since the late *** this study,we analyzed short-term instrumental seismic(focal mechanism)and long-term paleoseis-mic(Quaternary fault outcrop)data to decipher the neotectonic crustal deformation pattern in the south-eastern Korean ***(paleo-)seismic data acquired from an NNE–SSW trending deformation zone between the Yangsan and Ulleung fault zones indicate spatial partitioning of crustal deformation by NNW–SSE to NNE–SSW striking reverse faults and NNE–SSW striking strike-slip faults,supporting a strike-slip partitioned transpression *** instantaneous and finite neotectonic strains,estimated from the focal mechanism and Quaternary outcrop data,respectively,show discrepan-cies in their axes,which can be attributed to the switching between extensional and intermediate axes of finite strain during the accumulation of wrench-dominated ***,some major faults,including the Yangsan and Ulsan fault zones,are relatively misoriented to slip under the current stress condition but,paradoxically,have more(paleo-)seismic records indicating their role in accommodating the neotectonic transpressional *** propose that fluids,heat flow,and lithospheric structure are potential factors affecting the reactivation of the relatively misoriented major *** findings provide insights into the accommodation pattern of strain associated with the neotectonic crustal extrusion in an intraplate region of the eastern Eurasian Plate in response to the collision of the Indian Plate and the sub-duction of the Pacific/Philippine Sea Plates.

关键词： Transpression Strike-slip partition Intraplate strain accommodation Fault-slip analysis Slip tendency analysis

Winter distribution of diatom assemblages along the coastline of *** in 2010

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Acta Oceanologica Sinica 2022年第6期41卷 68-77页

作者： Joon Sang park Kyun-Woo Lee seung Won Jung Taek-Kyun Lee Hyoung Min Joo Library of Marine Samples Korea Institute of Ocean Science&TechnologyGeoje 53201R.O.Korea Marine Biotechnology Research Center Korea Institute of Ocean Science&TechnologyBusan 49111R.O.Korea Risk Assessment Research Center Korea Institute of Ocean Science&TechnologyGeoje 53201R.O.Korea Unit of Next Generation IBRV Building Program Korea Polar Research InstituteIncheon 21990R.O.Korea

Diatoms are a globally successful and eukaryotic photosynthetic organism with an ornamented silica external *** relationship between their valve morphology and habitat means that diatoms can be used as bioindicators to characterize the aquatic *** estimate the differential distribution and diversity of diatom assemblages along the coastal line,we collected phytoplankton samples from 114 coastal sites of waters of *** applied the unweighted pair-group technique using the arithmetic averages clustering method to cluster the sampling sites,apart from those where the biota consisted of other groups,such as dinoflagellates,into four regions:the Yellow Sea,South Sea,southern East Sea,and northern East *** species analysis in each region led to the selection of tychoplanktonic,chain-forming,attached species to substrates and psychrophilic indicator diatoms,respectively,each of which represented a planktonic lifestyle associated with one of the four *** study shows the diatom assemblages to serve as bioindicators of Korean coastal water in winter,and the subsequent seasonal survey will provide a starting point for the improved understanding of Korean diatom-based ecoregions,in both time and space.

关键词： diatom assemblage indicator species life-form Korean coastal waters species diversity

Plant-derived nanovesicles: Current understanding and applications for cancer therapy

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Bioactive Materials 2023年第4期22卷 365-383页

作者： Ngoc Phung Ly Hwa seung Han Myungsuk Kim Jae Hyung park Ki Young Choi Natural Product Informatics Research Center Korea Institute of Science and Technology(KIST)Gangneung25451Republic of Korea Division of Bio-Medical Science and Technology KIST SchoolUniversity of Science and Technology(UST)Seoul02792Republic of Korea School of Chemical Engineering College of EngineeringSungkyunkwan UniversitySuwon16419Republic of Korea Department of Health Sciences and Technology SAIHSTSungkyunkwan UniversitySeoul06351Republic of Korea Biomedical Institute for Convergence at SKKU Sungkyunkwan UniversitySuwon16419Republic of Korea

Plant-derived vesicles(PDVs)are membranous structures that originate from plant cells and are responsible for multiple physiological and pathological *** the last decade,PDVs have gained much attention for their involvement in different biological processes,including intercellular communication and defense response,and recent scientific evidence has opened a new avenue for their applications in cancer ***,much remains unknown about these vesicles,and current research remains *** review aims to provide a comprehensive introduction to PDVs,from their biological characteristics to purification methods,and to summarize the status of their potential development for cancer therapy.

关键词： Plant-derived vesicles Extracellular vesicles Cancer therapy Anti-cancer Drug delivery