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DEM simulation and characterization of copper and iron powders fabricated by ball milling

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Particuology 2024年第11期94卷 96-108页

作者： Khulan Uranchimeg Battsetseg Jargalsaikhan Lee Sang eui Heekyu choi Graduate School of Material Science Engineering Changwon National UniversityChangwonGyoungnam641-773Republic of Korea Citi University Ulaanbaatar 14201Mongolia Department of Mechatronics Convergence Engineering College of Future ConvergenceChangwon National UniversityChangwonGyoungnam641-773Republic of Korea Graduate School of Convergence on Culture Technology Changwon National UniversityChangwonGyoungnam641-773Republic of Korea Research Institute of Future Convergence Changwon National UniversityChangwonGyoungnam641-773Republic of Korea

In this study,the particle morphology,and size changes in copper and iron powders were investigated by using a high-energy ball mill under the same experimental *** particle sizes and morphologies of the powders were examined using a particle size analyzer and scanning electron microscopy(SEM).We also used the discrete element method(DEM)to analyze the ball impaction and the shear energy during the ball milling *** was discovered that the quantity of milling balls and rotational speed had a major impact on energy dissipation through heat and plastic deformation as well as milling *** characteristic(particle morphology and size)of the iron and copper powder were differently changed under the same experimental conditions,shear energy,and ball *** the particle sizes of copper and iron powder were compared under the same experimental conditions,the copper particle size increased from 21.6μm to 280μm,resulting in particle agglomeration,while the iron powder particle size decreased from 154μm to 4.35μm.

关键词： Copper powder Iron powder Ball size Particle morphology Particle size

Discriminative subgraphs for discovering family photos

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Computational Visual Media 2016年第3期2卷 257-266页

作者： Changmin choi YoonSeok Lee Sung-eui Yoon Korea Advanced Institute of Science and Technology (KAIST)

We propose to use discriminative subgraphs to discover family photos from group photos in an efficient and effective way. Group photos are represented as face graphs by identifying social contexts such as age, gender, and face position. The previous work utilized bag-of-word models and considered frequent subgraphs from all group photos as features for classification. This approach, however, produces numerous subgraphs, resulting in high ***, some of them are not *** solve these issues, we adopt a state-of-the-art,frequent subgraph mining method that removes nondiscriminative subgraphs. We also use TF-IDF normalization, which is more suitable for the bag-ofword model. To validate our method, we experiment in two datasets. Our method shows consistently better performance, higher accuracy in lower feature dimensions, compared to the previous method. We also integrate our method with the recent Microsoft face recognition API and release it in a public website.

关键词： image classification subgraph mining social context group photographs

Bioinspired magnetic cilia:from materials to applications

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Microsystems & Nanoengineering 2023年第6期9卷 107-128页

作者： Seongjin Park Geonjun choi Minsu Kang Woochan Kim Jangho Kim Hoon eui Jeong Department of Mechanical Engineering Ulsan National Institute of Science and Technology(UNIST)Ulsan44919Republic of Korea Department of Convergence Biosystems Engineering Chonnam National UniversityGwangju61186Republic of Korea Interdisciplinary Program in IT-Bio Convergence System Chonnam National UniversityGwangju61186Republic of Korea

Microscale and nanoscale cilia are ubiquitous in natural systems where they serve diverse biological *** artificial magnetic cilia have emerged as a highly promising technology with vast potential applications,ranging from soft robotics to highly precise *** this review,we comprehensively discuss the roles of cilia in nature and the various types of magnetic particles utilized in magnetic cilia;additionally,we explore the top-down and bottom-up fabrication techniques employed for their ***,we examine the various applications of magnetic cilia,including their use in soft robotics,droplet and particle control systems,fluidics,optical devices,and ***,we present our conclusions and the future outlook for magnetic cilia research and development,including the challenges that need to be overcome and the potential for further integration with emerging technologies.

关键词： magnetic overcome precise

Evaluation of properties of concrete using fluosilicate salts and metal (Ni,W) compounds

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中国有色金属学会会刊：英文版 2009年第B9期19卷 134-142页

作者： Gyu-yong KIM eui-Bae LEE Bae-Su KHIL Seung-Hun LEE Division of Architecture Engineering Chungnam National University Research Institute of Technology Tripod Co. Research Institute of Technology Samsung Construction and Engineering

To improve watertightness and antibiosis of sewage structure concrete, the antimicrobial watertight admixture was made with fluosilicate salts and antimicrobial compounds. And fresh properties, watertightness, harmlessness and antibiosis of concrete were investigated experimentally. As a result, the fresh properties of concrete were similar to those of an ordinary concrete, without setting time delay. Compressive strength and carbonation resistance of concrete were better than those of an ordinary concrete. Finally it was confirmed that the antimicrobial watertight admixture of concrete had an antibiosis inhibiting SOB growth.

关键词：抗菌化合物混凝土性能混凝土外加剂普通混凝土金属评价盐硅

Groundwater contamination and natural attenuation capacity at a petroleum spilled facility in Korea

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Journal of Environmental Sciences 2011年第10期23卷 1650-1659页

作者： Hyun-Mi choi Jin-yong Lee Department of Geology Kangwon National University

As a remedial option, the natural attenuation capacity of a petroleum contaminated groundwater at a military facility was examined. Hydrogeological conditions, such as high water level, permeable uppermost layer and frequent heavy rainfall, were favorable to natural attenuation at this site. The changes in the concentrations of electron acceptors and donors, as well as the relevant hydrochemical conditions, indicated the occurrence of aerobic respiration, denitrification, iron reduction, manganese reduction and sulfate reduction. The calculated BTEX expressed biodegradation capacity ranged between 20.52 and 33.67 mg/L, which appeared effective for the reduction of the contaminants levels. The contribution of each electron accepting process to the total biodegradation was in the order： denitrification 〉 iron reduction 〉 sulfate reduction 〉 aerobic respiration 〉 manganese reduction. The BTEX and benzene point attenuation rates were 0.0058-0.0064 and 0.0005-0.0032 day-1, respectively, and the remediation time was 0.7-1.2 and 2.5-30 years, respectively. The BTEX and benzene bulk attenuation rates were 8.69 × 10^-4 and 1.05 × 10^-3 day-l, respectively, and the remediation times for BTEX and benzene were 7.2 and 17.5 years, respectively. However, most of the natural attenuation occurring in this site can be attributed to dilution and dispersion. Consequently, the biodegradation and natural attenuation capacities were good enough to lower the contaminants levels, but their rates appeared to be insufficient to reach the remediation goal within a reasonable time frame. Therefore, some active remedial measures would be required.

关键词： petroleum contaminated site BTEX electron acceptor expressed biodegradation capacity natural attenuation

Magnesium citrate with a single dose of sodium phosphate for colonoscopy bowel preparation

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World Journal of Gastroenterology 2011年第2期17卷 242-248页

作者： yong Sung choi Jung Pil Suh Jong Kyu Kim In Taek Lee eui Gon Youk Doo Seok Lee Do Sun Kim Doo Han Lee Department of Gastroenterology Daehang Hospital Department of Surgery Daehang Hospital

AIM:To evaluate the efficacy and acceptability of magnesium citrate and a single dose of oral sodium phosphate(45 mL) solution for morning colonoscopy bowel preparation. METHODS:A total of 159 patients were randomly assigned to receive two split doses of 90 mg of sodium phosphate(GroupⅠ,n=79) or magnesium citrate(250 mL,the day before the procedure) followed by 45 mL of sodium phosphate(the day of procedure,GroupⅡ,n= 80) .The quality of bowel cleansing and the acceptability of each regimen were compared,including the satisfaction,taste,willing to repeat and adverse effects of each regimen. RESULTS:The quality of bowel cleansing of GroupⅡ was as good as that of GroupⅠ(An Aronchick scale score of good or excellent:70.9%vs 81.0%,respectively,P=0.34;the Ottawa system score:4.4±2.6 vs 3.8 ±3.0,respectively,P=0.76) .There was no statisticallysignificant difference between both groups with regard to acceptability,including the satisfaction,taste and willingness to repeat the regimen.A significantly greater number of older patients(over 65 years old) in Group Ⅱgraded the overall satisfaction as satisfactory(48.1% vs 78.1%,respectively;GroupⅠvs GroupⅡ,P=0.01) . There were no significant adverse reactions. CONCLUSION:Magnesium citrate and a single dose of sodium phosphate was as effective and tolerable as the conventional sodium phosphate regimen and is a satisfactory option.

关键词： Colonoscopy Bowel preparation Efficacy Acceptability Magnesium citrate Sodium phosphate

Material properties and machining performance of hybrid Ti_2AlN bulk material for micro electrical discharge machining

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中国有色金属学会会刊：英文版 2012年第S3期22卷 781-786页

作者： eui-Seong choi Jinwoo SUNG Qi-min WANG Kwang-Ho KIM Ahmed BUSNAINA Myung Chang KANG National Core Research Center for Hybrid Materials Solution Pusan National University School of Mechanical and Electronic Engineering Guangdong University of Technology Department of Mechanical and Industrial Engineering College of EngineeringNortheastern University

Mn+1AXn(MAX) phases are a family of nanolaminated compounds that possess unique combination of typical ceramic properties and typical metallic *** a member of MAX phase,Ti2 AlN bulk materials are attractive for some high-temperature *** synthesis,characteristics and machining performance of hybrid Ti2 AlN bulk materials were focused on in this *** bulk samples mainly consisting of Ti2 AlN MAX phase with density close to theoretic one were synthesized by a spark plasma sintering *** electron microscopy results indicate homogenous distribution of Ti2 AlN grains in the ***-hardness values are almost constant under different loads (6-6.5 GPa).A machining test was carried out to compare the effect of material properties on micro-electrical discharge machining (micro-EDM) performance for Ti2 AlN bulk samples and Ti6242 *** machining performance of the Ti2 AlN sample is better than that of the Ti6242 *** inherent mechanism was discussed by considering their electrical and thermal conductivity.

关键词： hybrid Ti2AlN bulk micro-electrical discharge machining electrical conductivity micro-hole shape

Black esophagus with concomitant candidiasis developed after diabetic ketoacidosis

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World Journal of Gastroenterology 2007年第42期13卷 5662-5663页

作者： yong Hwan Kim Si Young choi Department of Thoracic and Cardiovascular Surgery Uijeongbu St. Mary's Hospital The Catholic University of Korea College of Medicine Seoul 480-821 Korea Department of Thoracic and Cardiovascular Surgery Uijeongbu St. Mary’s Hospital The Catholic University of Korea College of Medicine Seoul 480-821 Korea

Black esophagus is a very rare disease and its pathogenesis has been *** esophagus developed concomitantly with candidiasis after diabetic ketoacidosis has not been reported *** report a case who developed esophageal stricture after the treatment of black esophagus and thus balloon dilatation was performed several times but failed,hence,surgical treatment was performed.

关键词： Esophagus Candidiasis Diabetic ketoacidosis Surgery

Increased type III interferons and NK cell functions in SARS-CoV-2-infected children

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Signal Transduction and Targeted Therapy 2023年第3期8卷 888-890页

作者： Seong Dong Jeong Hoyoung Lee Ju Young Chang Seong yong Lee Ji Eun choi Eunmi Yang Hye Won Jeong Jae-Phil choi Mi Seon Han eui-Cheol Shin The Center for Viral Immunology Korea Virus Research InstituteInstitute for Basic Science(IBS)Daejeon 34126Republic of Korea Department of Pediatrics Seoul Metropolitan Government-Seoul National University Boramae Medical Center and Seoul National University of College of MedicineSeoul 07061Republic of Korea Division of infectious diseases Seoul Medical CenterSeoul 02053Republic of Korea Department of Internal Medicine Chungbuk National University College of MedicineCheongju 28644Republic of Korea Graduate School of Medical Science and Engineering Korea Advanced Institute of Science and Technology(KAIST)Daejeon 34141Republic of Korea

Dear Editor,Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection is more likely to progress to severe disease in the elderly,and the rates of hospitalization for coronavirus disease 2019(COVID-19)increase with age.1,2 Herein,we comprehensively compared adaptive and innate immune responses between children and adults infected with SARS-CoV-2.

关键词： infected acute respiratory