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Investigation into charge carrier dynamics in organic light-emitting diodes

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Nano Research Energy 2024年第2期3卷 39-46页

作者： Dong-Guang Zheng Hyeon-Dong Lee Gyeong Won Lee Dong-soo Shin Jeongwon Kim Jong-In Shim Zhiqun Lin tae-Woo Lee Dong Ha Kim Information Engineering College Hangzhou Dianzi UniversityHangzhou 311305China Department of Materials Science and Engineering Seoul National University1 Gwanak-roGwanak-guSeoul 08826Republic of Korea Department of Photonics and Nanoelectronics Hanyang University ERICA55 Hanyangdeahak-roSangnok-guAnsanGyeonggi 15588Republic of Korea Department of Chemistry and Nanoscience Ewha Womans University52Ewhayeodae-gilSeodaemun-guSeoul 03760Republic of Korea Department of Chemical and Biomolecular Engineering National University of Singapore4 Engineering Drive 4Singapore 117585Singapore School of Chemical and Biological Engineering Institute of Engineering ResearchResearch Institute of Advanced MaterialsSoft FoundrySeoul National University1 Gwanak-roGwanak-guSeoul 08826Republic of Korea Basic Sciences Research Institute(Priority Research Institute) Ewha Womans UniversitySeoul 03760Republic of Korea Nanobio∙Energy Materials Center(National Research Facilities and Equipment Center) Ewha Womans UniversitySeoul 03760Republic of Korea

Organic light-emitting diodes(OLEDs)have demonstrated remarkable advancements in both device lifetime and luminous ***,insufficient operation lifetime due to device degradation remains a major hurdle,especially for brighter *** the degradation mechanisms of OLEDs due to the degradation of functional materials and the formation of defects in device architectures continues to be a significant ***,we evaluate the degradation characteristics by scrutinizing the electrical and optical properties,as well as analyzing the charge carrier dynamics in pristine and aged states of phosphorescent OLEDs(PhOLEDs).We show that degradation mechanisms in PhOLEDs can be elucidated in terms of the ideality factors of current and luminance in pristine and aged device *** consistent shifts in distinct ideality factors across various states points out that the device degradation is attributed to the deterioration of the guest material,***-light-emitting phosphorescent ***,the incongruity in ideality factor changes between the two states indicates that the degradation results from the deterioration of non-light-emitting *** characterization experiments provide further evidence that this degradation is primarily attributed to the deterioration of CBP-host *** thorough understanding of degradation mechanisms established in this study can contribute to realizing the highly reliable PhOLEDs with a long lifetime.

关键词： organic light-emitting diodes ideality factor carrier transport processes degradation mechanism

Velocity Profiles between Two Baffles in a Shell and Tube Heat Exchanger

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Journal of Thermal Science 2015年第4期24卷 356-363页

作者： tae-Hyun Chang Chang-Hoan Lee Hae-soo Lee Kwon-soo Lee Senior Research Fellow of RESEAT Korea Institute of Science and Technology Information Korea Institute of Science and Technology Information Postdoctoral Research Fellow School of Mechanical Engineering of Kyungnam University International University of Korea

Heat exchangers are extensively utilized for waste heat recovery,oil refining,chemical processing,and steam *** this study,velocity profiles are measured using a 3D particle image velocimetry(PIV)system between two baffles in a shell and tube heat exchanger for parallel and counter *** PIV and computational fluid dynamics results show the occurrence of some strong vectors near the *** vectors are assumed due to the clearance between the inner tubes and the front ***,the major parts of the vectors are moved out through the bottom opening of the rear baffle,and other vectors produce a large circle between the two *** simulations are conducted to investigate the effects of the baffle on the heat exchanger using the Fluent *** k-εturbulence model is employed to calculate the flows along the heat exchanger.

关键词： Baffle P1V Shell and tube heat exchanger Cut off ratio CFD

Generation of mesenchymal stem-like cells for producing extracellular vesicles

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World Journal of Stem Cells 2019年第5期11卷 270-280页

作者： soo Kim tae Min Kim Brexogen Research Center Brexogen Inc. Seoul Songpa-gu 05718 South Korea Graduate School of International Agricultural Technology and Institute of Green- Bio Science and Technology Seoul National University Gangwon-do Pyeongchang 25354 South Korea

Mesenchymal stem cells (MSCs) are multipotent progenitor cells with therapeutic potential against autoimmune diseases, inflammation, ischemia, and metabolic disorders. Contrary to the previous conceptions, recent studies have revealed that the tissue repair and immunomodulatory functions of MSCs are largely attributed to their secretome, rather than their potential to differentiate into desired cell types. The composition of MSC secretome encompasses cytokines and growth factors, in addition to the cell-derived structures known as extracellular vesicles (EVs). EVs are membrane-enclosed nanoparticles that are capable of delivering biomolecules, and it is now believed that MSC-derived EVs are the major players that induce biological changes in the target tissues. Based on these EVs’ characteristics, the potential of EVs derived from MSC (MSC-EV) in terms of tissue regeneration and immune modulation has grown during the last decade. However, the use of MSCs for producing sufficient amount of EVs has not been satisfactory due to limitations in the cell growth and large variations among the donor cell types. In this regard, pluripotent stem cells (PSCs)-derived MSC-like cells, which can be robustly induced and expanded in vitro, have emerged as more accessible cell source that can overcome current limitations of using MSCs for EV production. In this review, we have highlighted the methods of generating MSC-like cells from PSCs and their therapeutic outcome in preclinical studies. Finally, we have also discussed future requirements for making this cell-free therapy clinically feasible.

关键词： Mesenchymal stem cells Extracellular vesicles Preclinical studies Exosomes

Pancreatic parenchymal injection of ethanol and octreotide to induce focal pancreatic fibrosis in rats: Strategies to eliminate postoperative pancreatic fistula

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Hepatobiliary & Pancreatic Diseases International 2018年第1期17卷 81-85页

作者： soo Ho Lee tae Ho Hong Department of Surgery Uijeongbu St.Mary’s Hospital College of Medicine The Catholic University of Korea Department of Surgery Seoul St.Mary’s Hospital College of Medicine The Catholic University of Korea

Background: Postoperative pancreatic fistula(POPF) is more likely to occur in a soft pancreas compared to a hard pancreas in which fibrosis has progressed. There is almost no leakage at the anastomosis site or cut surface of a hard pancreas. The aim of this study was to induce localized fibrosis at the cut surface of the pancreas in a rat ***: Thirty-six rats were divided into three groups(group S: normal saline group; group E: ethanol group; and group O: octreotide group). Each rat was directly injected with a particular compound at the duodenal lobe of the pancreatic parenchyma. Each group was divided into three subgroups according to the time of post-injection sacrifice(1, 2, or 4 weeks). The hardness, suture holding capacity(SHC), and histological fibrosis grade of each pancreas were ***: The hardness, SHC, and fibrosis grade of groups E and O were increased at week 1, with greater increases in group E(all P < 0.001). In a subgroup comparison, the hardness, SHC, and fibrosis grade of group E tended to decrease gradually over time, with no regular pattern evident in group O. A comparison between the injected site(duodenal lobe) and non-injected site(splenic lobe) of the pancreas revealed increases in the three parameters of group E only in the duodenal lobe, with increases in group O at both the duodenal and splenic ***: Parenchymal injection of ethanol and octreotide increased pancreatic fibrosis. Unlike octreotide, ethanol provoked localized fibrosis that was maintained over time. It is expected that ethanol injection could eliminate POPF during pancreatic surgery.

关键词： Ethanol Octreotide Pancreatic fibrosis Pancreatic fistula Rat model

Ultimate strength of single shear bolted connections with cold-formed ferritic stainless steel

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第2期14卷 120-136页

作者： Jin-seong LIM tae-soo KIM Seung-hun KIM Department of Architectural Engineering Hanbat National UniversityDaejeon 305-719Korea

This paper is focused on the structural behavior of the single shear bolted connections with thin-walled ferritic stainless *** purpose of this study is to investigate the ultimate behaviors,such as ultimate strength and fracture mode of the single shear bolted connections of thin-walled ferritic stainless steel(low cost steel) rather than austenitic stainless steel(high cost steel).Bolt arrangement and end distance parallel to the direction of applied load are considered as main variables of the test specimens for bolted *** have a constant dimension of edge distance perpendicular to the loading direction,bolt diameter,pitch,and gauge.A monotonic tensile test for specimens has been carried out and some bolted connections with long end distance showed curling(out of plane deformation) occurrence which led to strength *** ultimate behaviors such as fracture mode,ultimate strength are compared with those predicted by current design ***,conditions of curling occurrence and the strength reduction due to curling are investigated and modified strength equations are suggested considering the curling effect.

关键词： Cold-formed ferritic stainless steel Bolted connection Bolt arrangement End distance Curling Strength reduction

Influence of operational parameters on the photocatalytic performance of DE-NOx process Via MIL-101(Fe)

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Progress in Natural Science:Materials International 2018年第6期28卷 689-695页

作者： Hoang Phuc Nguyen tae Ho Kim soo Wohn Lee Research Center for Eco Multi-Functional Nano Materials Sun Moon University Department of Environmental & Bio-Chemical Engineering Sun Moon University

Metal organic framework(MOF)has been paid great attention as a potential candidate for various applications in the field of energy and environment,particularly in air *** various MOFs,MIL-101(Fe) represents an interesting material possessing many advantages,including the ease of fabrication,high porosity,high specific surface area with open metal sites,making it a promising material in the field of harmful gas *** these advantages,MIL-101(Fe) was synthesized by facile microwave-solvothermal method and applied as a photocatalyst for the degradation of *** de-NOxefficiency of the synthesized powder was evaluated with respect to various operating parameters including substrates,sample doses,light spectrum and light intensity,initial NO concentration,and relative *** results have shown that the efficiency of NOxphotocatalytic degradation reaches to 77%under solar irradiation via 0.1 g of MIL-101(Fe) with optimum condition of reaction,(alumina substrate,350 ppb of initial NO concentration,40–50%of relative humidity).Then this work provides the optimum condition for the efficient photocatalytic degradation of NOx.

关键词： Metal-organic framework MIL-101 Gaseous pollutant NOx emission Photocatalyst

Chuna Therapy for Musculoskeletal Pain:A Systematic Review of Randomized Clinical Trials in Korean Literature

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Chinese Journal of Integrative Medicine 2013年第3期19卷 228-232页

作者： tae-Woong Moon tae-Young Choi tae-Yong Park Myeong soo Lee Brain Disease Research Center Korea Institute of Oriental Medicine

Objective： To evaluate the effectiveness of Chuna for the treatment of musculoskeletal pain as reported in Korean literature. Methods： We conducted an electronic literature search using seven Korean databases and manually searched six traditional Korean medicine journals. Risk of bias was assessed with the Cochrane criteria. Results： Six randomized controlled trials （RCTs） were included in the study. Compared with standard care, three RCTs suggested favorable effects of Chuna on neck pain due to a hypolordotic cervical spine, low back pain caused by traffic accidents, and low back pain. In contrast, compared with standard care, three RCTs failed to show positive effects on temporomandibular joint disorder, mandibular movement, and neck pain caused by traffic accidents. Conclusions： Currently, the evidence of the effectiveness of Chuna for the treatment of musculoskeletal pain is not convincing. Further rigorously designed trials are warranted to determine its effectiveness.

关键词： Chuna musculoskeletal pain systematic review Korean literature

Influence of tool plunge depth and welding distance on friction stir lap welding of AA5454-O aluminum alloy plates with different thicknesses

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中国有色金属学会会刊：英文版 2012年第S3期22卷 624-628页

作者： Jun-Won KWON Myoung-soo kang Sung-Ook YOON Yong-Jai KWON Sung-tae HONG Dae-Il KIM Kwang-Hak LEE Jong-Dock SEO Jin-soo MOON Kyung-Sik HAN School of Materials Science and Engineering University of Ulsan School of Mechanical Engineering University of Ulsan Technical Research Laboratories Shin Young Co.Ltd. Automotive Parts Innovation Center Ulsan Technopark

AA5454-O aluminum alloy plates with thicknesses of 1.4 and 1.0 mm were friction-stir-lap-welded (FSLWed).The influences of the tool plunge depth and welding distance on surface appearance,macrostructure and mechanical properties of the FSLWed plates were experimentally *** tensile shear load of the FSLWed plates was compared with that of the adhesive-bonded ***-free FSLWed zones were successfully obtained in all the tool plunge depths and the welding *** FSLWed zones exhibited the relatively smooth surface *** all the FSLWed conditions,the FSLWed zone exhibited higher average hardness than the base *** addition,the upper plate exhibited a higher average hardness than the lower plate,although there was no special tendency in spite of the change in the tool plunge depth and the welding *** maximum tensile shear load of the FSLWed plates was much higher than that of the adhesive-bonded aluminum alloy ***,under the FSLW condition of the plunge depth of 1.8 mm and the welding distance of 40 mm,the tensile shear load of the FSLWed plate reached a level about 41% greater than that of the adhesive-bonded aluminum alloy *** addition,the maximum tensile shear load of the FSLWed plate was increased with the increase of the welding distance.

关键词： friction stir lap welding AA5450-O aluminum alloy tool plunge depth welding distance mechanical properties

Microstructure and Mechanical Properties of TiB-Containing Al–Zn Binary Alloys

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Journal of Materials Science & Technology 2016年第7期32卷 653-659页

作者： Sang-soo Shin Gil-Yong Yeom tae-Yang Kwak Ik-Min Park Department of Materials Science and Engineering Pusan National University Busan 609-735 Republic of Korea Liquid Processing & Casting Technology R&BD Group Korea Institute of Industrial Technology Incheon 21999 Republic of Korea

The microstructure and mechanical properties of newly developed Al-35Zn cast alloys with TiB refiner addition were evaluated by X-ray diffractometry, optical microscopy, and scanning electron microscopy coupled with energy dispersive spectrometry. The microstructure of these alloys featured α-Al den- drites surrounded by AI-Zn （α ＋ rI） eutectic structures. After the addition of TiB refiner, the alloy grain sizes decreased, and its morphology abruptly changed from dendritic to equiaxed grains. Such an im- proved microstructure of the modified alloys was accompanied by a significant increase in the tensile strength and elongation percentage compared to those of the AI-Zn or Zn-Al-based alloys. The results showed that with the increase of TiB content up to 0.05%, the morphology of α-Al dendrites and α ＋ T1 phases changed from coarse dendrite and lamellar structures into independent and fine ones. Based on these results, the effect of TiB refiner addition on the microstructure and mechanical properties of the AI-35Zn binary alloys was investigated.

关键词： Al-Zn(-Cu) alloyEutectic structureHigh strengthTiB2