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Impregnation approach for poly(vinylidene fluoride)/tin oxide nanotube composites with high tribological performance

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Journal of Materials Science & Technology 2020年第2期37卷 19-25页

作者： Min su park Jin Kyu Kim Tong-Seok Han Jung Tae park Jong Hak Kim Department of Chemical and Biomolecular Engineering Yonsei University50 Yonsei-roSeodaemun-guSeoul03722Korea Department of Civil and Environmental Engineering Yonsei University50 Yonsei-roSeodaemun-guSeoul03722Korea Department of Chemical Engineering Konkuk University120 Neungdong-roGwangjin-guSeoul05029Korea

We report a composite material with the high tribological performance,which consists of onedimensional SnO2 nanotubes(ST)and a high molecular weight poly(vinylidene fluoride)(PVDF)matrix in terms of *** of PVDF in N,N-dimethylformamide(DMF)resulted in a facile penetration of PVDF into the inner hollow voids of ST,leading to the close *** between PVDF and ST results in a beneficial effect on the chain arrangement of PVDF,providing anα-phase with better tribological *** ST incorporation,the friction coefficient decreased by 85.0%to 0.408,and the specific wear rate decreased by 69.1%to 0.412,demonstrating the pivotal role of ST as a self-lubricating material due to a large interactive area and PVDF chain rearrangement.

关键词： SnO2 nanotube Composite Friction coefficient Wear rate

Net Effect of Short-Term Smoking Cessation on Mental Health Changes:Inverse Probability of Treatment Weighting and Difference-in-Differences Method

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International Journal of Mental Health Promotion 2024年第9期26卷 745-755页

作者： Ji-su park Tae-Hyeon Lee Il-su park Busan Eastern Branch of Korea Association of Health Promotion Busan47734Republic of Korea Department of Biomedical Health Science Graduate SchoolDong-Eui UniversityBusan47340Republic of Korea Department of Healthcare Management Dong-Eui UniversityBusan47340Republic of Korea

Background:In response to the need for research clearly demonstrating the net effect of smoking cessation on mental health status,considering the causal relationship between smoking cessation and changes in mental health status,this study was ***,this study aimed to examine the net effect of short-term smoking cessation on five specific mental health metrics and the overall mental health status ***:We used data from the first wave of the Korean Health Panel(KHP)survey(2011–2013,2016–2018)and focused on men aged 19 years and older,to explore the effects of smoking *** compared mental health status before and after cessation among current non-smokers who had quit smoking and continuous *** ensured homogeneity between the two groups via inverse probability of treatment weighting(IPTW)and employed a difference-in-differences(DID)analysis to assess changes in mental health *** study controlled for factors that could influence mental health and explored the net effect of short-term smoking cessation through difference-in-differences model using multiple regression ***:The results showed that short-term smoking cessation significantly alleviated mental and physical stress(psults highlight a meaningful link between positive health behavior changes,such as smoking cessation,and enhanced mental ***,the application of temporal variables further improved the understanding of the causal relationship between health behaviors and mental health.

关键词： Smoking cessation mental health Korea health panel survey BEPSI-K IPTW DID

Recent application of biochar on the catalytic biorefinery and environmental processes

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Chinese Chemical Letters 2019年第12期30卷 2147-2150页

作者： Hyung Won Lee Heejin Lee Young-Min Kim Rae-su park Young-Kwon park School of Environmental Engineering University of SeoulSeoul 02504Republic of Korea Department of Environmental Engineering Daegu UniversityGyeongsan 38452Republic of Korea Department of Bioenvironmental&Chemical Engineering Chosun College of Science&TechnologyGwangju 61453Republic of Korea

Lignocellulosic biomass is an abundant and environment-friendly source for renewable energy *** value and application of biochar,which is obtained from the thermochemical conversion of biomass,is increasing rapidly because of its high carbon content and *** property of biochar,such as surface area,porosity,and number of functional groups,can be improved by controlling the conditions of biomass conversion,biochar activation,and functionalization *** production and activation of biochar as well as its potential use for soil remediation,pollutant adsorption,and biorefinery have been reviewed extensively over recent *** paper provides a conceptual approach for biochar production and activation together with its application as a catalyst for biorefineries and the removal of environmental contaminants.

关键词： Biomass Thermochemical conversion Biochar Activation Catalyst

Experiments and computer simulation analysis of impact behaviors of micro-sized abrasive in waterjet cutting of thin multiple layered materials

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中国有色金属学会会刊：英文版 2012年第S3期22卷 864-869页

作者： Jung-Han LEE Kang-su park Myung Chang KANG Bo Sik KANG Bo sung SHIN Engineering Research Center Pusan National University National Core Research Center Pusan National University Mechanical System Safety Research Division Korea Institute of Machinery and Materials

The abrasive waterjet (AWJ) is now widely used in the advanced cutting processes of polymers,metals,glass,ceramics and composite materials like thin multiple-layered material (TMM).Various research and development efforts have recently been made to understand the science of ***,the interaction mechanism between a workpiece and high-velocity abrasive particles still remains a complicated *** this work,the material removal mechanisms of AWJ such as micro penetration and micro dent were experimentally *** addition,a new computer simulation model considering high strain rate effect was proposed to understand the micro impact behavior of high-velocity micro-sized abrasives in AWJ cutting.

关键词： abrasive waterjet thin multiple layered materials micro-sized abrasive micro penetration micro dent

Application of response surface method for optimal transfer conditions of multi-layer ceramic capacitor alignment system

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Journal of Central South University 2011年第3期18卷 726-730页

作者： park su-seong KIM Jae-min CHUNG Won-jee SHIN O-chul School of Mechatronics Changwon National University

The multi-layer ceramic capacitor (MLCC) alignment system aims at the inter-process automation between the first and the second plastic *** a result of testing performance verification of MLCC alignment system,the average alignment rates are 95% for 3216 chip,88.5% for 2012 chip and 90.8% for 3818 *** MLCC alignment system can be accepted for practical use because the average manual alignment is just 80%.In other words,the developed MLCC alignment system has been upgraded to a great extent,compared with manual *** on the successfully developed MLCC alignment system,the optimal transfer conditions have been explored by using *** simulations using ADAMS has been performed according to the cube model of *** using MiniTAB,the model of response surface has been established based on the simulation *** optimal conditions resulted from the response optimization tool of MiniTAB has been verified by being assigned to the prototype of MLCC alignment system.

关键词： multi-layer ceramic capacitor (MLCC) alignment system response surface method (RSM) MiniTAB ADAMS

Topology optimization of reactive material structures for penetrative projectiles

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Defence Technology（防务技术） 2022年第7期18卷 1205-1218页

作者： Shinyu Kim Saekyeol Kim Taekyun Kim Sangin Choi Tae Hee Lee Jung su park Sang-Hyun Jung Department of Automotive Engineering Hanyang University222 Wangsimni-roSeongdong-guSeoul04763Republic of Korea The 4th R&D Institute Agency for Defense Development35Yuseong P.O.BoxDaejeon34186Republic of Korea

Recently,reactive materials have been developed for penetrative projectiles to improve impact resistance and energy ***,the design of a reactive material structure,involving shape and size,is challenging because of difficulties such as high non-linearity of impact resistance,manufacturing limitations of reactive materials and high expenses of penetration *** this study,a design optimization methodology for the reactive material structure is developed based on the finite element analysis.A finite element model for penetration analysis is introduced to save the expenses of the *** resistance is assessed through the analysis,and result is calibrated by comparing with experimental *** on the model,topology optimization is introduced to determine shape of the *** design variables and constraints of the optimization are proposed considering the manufacturing limitations,and the optimal shape that can be manufactured by cold spraying is *** on the optimal shape,size optimization is introduced to determine the geometric dimensions of the *** a result,optimal design of the reactive material structure and steel case of the penetrative projectile,which maximizes the impact resistance,is *** the design process proposed in this study,reactive material structures can be designed considering not only mechanical performances but also manufacturing limitations,with reasonable time and cost.

关键词： Reactive material Penetrative projectile Topology optimization Manufacturing constraint Cold gas dynamic spray Additive manufacturing

A Self‑Regenerable Fiber Sloughing Its Heavy Metal Skin for Ultrahigh Separation Capability

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Advanced Fiber Materials 2023年第6期5卷 2127-2142页

作者： Youngkyun Jung Ji su park Kyung‑Won Jung Young Gun Ko Jae‑Woo Choi Center for Water Cycle Research Korea Institute of Science and TechnologySeoul 02792Republic of Korea Center for Bionics Korea Institute of Science and TechnologySeoul 02792Republic of Korea Department of Chemical Engineering and Materials Science Sangmyung UniversitySeoul 03016Republic of Korea Division of Energy&Environment Technology KIST SchoolKorea University of Science and Technology(UST)Seoul 02792Republic of Korea

Developing efficient separation materials for recovering metal resources from aqueous environments is crucial for the sustainable water–food–energy nexus,which addresses the interdependence between energy production,water production,and energy *** material-based separation processes have demonstrated outstanding ***,electric energy and chemicals are used to frequently replace the separation materials used in such processes owing to their short life *** study presents a methodology for designing the self-regenerable fiber(SRF)according to the types of metals through a self-regeneration *** SRF can semi-permanently recover the metal resources from water through a repetitive adsorption–crystallization–detachment process of metal ions on its *** ionic metal resources are adsorbed and crystallized with the counter-anions on the SRF ***,the metal crystals are self-detached from the SRF surface by the collision between the crystals and curvature and non-sticky surface of the ***,a module containing the SRF maintains its metal recovery capability even during continuous injection of the metal solution without its *** findings highlight the significance of interfacial engineering and further guide the rational design of energy/environmentally friendly resource recovery modules.

关键词： Self-regeneration model Self-regenerable fiber Semi-permanent adsorption capability Metal crystal growth-detachment

Fabrication of 3D Printed PCL/PEG Polyblend Scaffold Using Rapid Prototyping System for Bone Tissue Engineering Application

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Journal of Bionic Engineering 2018年第3期15卷 435-442页

作者： su A park Sang Jin Lee Ji Min Seok Jun Hee Lee Wan Doo Kim Il Keun Kwon Department of Nature-Inspired Nanoconvergence Systems Korea Institute of Machinery and Materials 156 Gajeongbuk-ro Yuseong-gu Daejeon 34103 Republic of Korea Department of Dental Materials School of Dentistry Kyung Hee University 26 Kyungheedae-ro Dongdaemun-gu Seou102447 Republic of Korea

Three-dimensional （3D） printing is a novel process used to manufacture bone tissue engineered scaffolds. This process allows for easy control of the architecture at the micro structure. However, the scaffold properties are typically limited in terms of cellular activity at the scaffold surface due to the printed materials properties. In this study, we developed a polycaprolactone （PCL） blended with polyethylene glycol （PEG） 3D printed scaffold using a rapid prototyping system. The manufactured scaffolds were then washed out to form small pores on the surface in order to improve the scaffolds hydrophilicity. We analyzed the resultant material by using Scanning Electron Microscopy （SEM）, water absorption, water contact angle, in vitro WST-1, and the Bradford assay. Additionally, cells incubated on the fabricated scaffolds were visualized by Confocal Laser Scanning Microscopy （CLSM）. The developed scaffolds exhibited small pores on the strand surface which served to increase hydrophilicity as well as improve cellular proliferation and increase total protein content. Our findings suggest that the presence of small pores on the scaffolds can be used as an effective tool for improving implant cellular interaction. This research indicates that these modified scaffolds can be considered useful for bone tissue engineering applications to improve human health.

关键词： polycaprolactone polyethylene glycol polyblend 3D printing porosity bone tissue engineering

Fabrication and characterization of 3D scaffold using 3D plotting system

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Chinese Science Bulletin 2010年第1期55卷 94-98页

作者： LEE Jun-Hee park su-a park KoEun KIM Jae-Hyun KIM Kyung-Shik LEE Jihye Kim WanDoo Bio-Mechatronics Team Division of Nano-Machinery Korea Institute of Machinery and Materials (KIMM) Nano-Mechanics Team Division of Nano-Machinery Korea Institute of Machinery and Materials (KIMM) Nano-Mechatronics Team Division of Nano-Machinery Korea Institute of Machinery and Materials (KIMM)

In this paper, we design and fabricate a 3D scaffold using rapid prototyping (RP) technology for tissue engineering. The scaffold should have a three-dimensional interconnected pore network. We fabricate a polycaprolactone (PCL) scaffold with interconnecting pores and uniform porosity for cell ingrowth using a 3D plotting system. In order to keep the three dimensional shape under mechanical loading while implanted, we design an oscillating nozzle system to increase elastic modulus and yield strength of PCL strand. We characterize the influence of pore geometry, compressive modulus of the scaffold, elastic modulus and yield strength of the strand using SEM, dynamical mechanical analysis (DMA) and Nano-UTM. Finally the cell responses on scaffolds are observed.

关键词：三维形状绘图系统表征支架制作动态机械分析弹性模量细胞反应