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FEA technique of hot plate forming process using cell-typed die with cooling device

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中国有色金属学会会刊：英文版 2012年第S3期22卷 831-837页

作者： Jung-Min lee In-Kyu lee Kyung-Hun lee dae-Soon KIM Byung-Min KIM Dongnam Regional Division Korea Institute of Industrial Technology School of Mechanical Engineering Pusan National University Industrial Technology Division Hyundai Heavy Industries

Hot plate forming using a cell-typed die is a process for forming a large thick plate with a spherical shape for the manufacture of a large spherical LNG ***-typed upper and lower dies made of a framework of steel plates fitted to make a grid pattern are used in this process,and an air-cooling device is separately installed inside the lower die.A finite element analysis (FEA) technique was developed,which included hot forming,air flow,cooling and thermal deformation analysis for the hot plate forming process using the cell-typed ***,the convective and interface heat transfer coefficients were used to reproduce analytically the effects of the cooling device in the hot plate forming analysis.A small-scale model test of the process was conducted to verify the FEA *** analysis results show that the curvature of the final plate agrees well with that of the designed experiment within a maximum relative error of 0.03% at the corner of the plate.

关键词： cell-typed die hot plate forming spherical LNG tank heat transfer coefficient

Underlying mechanisms of variation in yield asymmetry and strain hardening behavior of extruded pure Mg with Gd addition

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Journal of Magnesium and Alloys 2023年第6期11卷 2165-2181页

作者： Gyo Myeong lee sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

Effects of Gd addition on the strain hardening behavior and yield asymmetry of pure Mg are investigated by subjecting extruded pure Mg,Mg–5Gd,and Mg–15Gd(all in wt%)to tension and compression tests along the extrusion direction(ED).As the amount of Gd added to pure Mg increases,the basal texture tilts toward the ED and the distribution of c-axes of grains becomes *** tension,the strain hardening rates of all the materials decrease until ***,under compression,the strain hardening rate increases in the early stage of deformation in pure Mg and Mg–5Gd,whereas it continuously decreases in Mg–*** Mg exhibits considerably high tension-compression yield asymmetry,with a compressive yield strength(CYS)to tensile yield strength(TYS)ratio of *** contrast,Mg–5Gd exhibits excellent yield symmetry with CYS/TYS of 0.9 and Mg–15Gd exhibits reversed yield asymmetry with CYS/TYS of *** mechanisms of these drastically different Gd-addition-induced deformation behaviors of the materials are discussed in terms of the crystallographic distribution of grains and the relative activation stresses of basal slip,prismatic slip,pyramidal slip,and{10–12}twinning under tension and compression.

关键词： Pure Mg Gd addition Texture Yield asymmetry Activation stress

Polymer efficiency and sulfate concentration for hybrid EOR application to an acidic carbonate reservoir

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Petroleum Science 2023年第2期20卷 993-1004页

作者： Yeonkyeong lee Wonmo sung Jihoon Wang Korea Institute of Geoscience and Mineral Resources 124 Gwahak-roYuseong-guDaejeon34132Republic of Korea Department of Earth Resources and Environmental Engineering Hanyang University222 Wangsimni-roSeongdong-guSeoul04763Republic of Korea

Polymers play an important role in hybrid enhanced oil recovery (EOR), which involves both a polymer and low-salinity water. Because the polymer commonly used for low-salinity polymer flooding (LSPF) is strongly sensitive to brine pH, its efficiency can deteriorate in carbonate reservoirs containing highly acidic formation water. In this study, polymer efficiency in an acidic carbonate reservoir was investigated experimentally for different salinity levels and SO42− concentrations. Results indicated that lowering salinity improved polymer stability, resulting in less polymer adsorption, greater wettability alteration, and ultimately, higher oil recovery. However, low salinity may not be desirable for LSPF if the injected fluid does not contain a sufficient number of sulfate (SO42−) ions. Analysis of polymer efficiency showed that more oil can be produced with the same polymer concentration by adjusting the SO42− content. Therefore, when river water, which is relatively easily available in onshore fields, is designed to be injected into an acidic carbonate reservoir, the LSPF method proposed in this study can be a reliable and environmentally friendly method with addition of a sufficient number of SO42− ions to river water.

关键词： Polymer efficiency Low-salinity polymer flooding Polymer adsorption Wettability alteration Sulfate ion Acidic carbonate reservoir

Bright and stable near-infrared perovskite light emitters supported by multifunctional molecule design strategy

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Light(Science & Applications) 2023年第10期12卷 1995-1997页

作者： Joo sung Kim Tae-Woo lee SN Display Co.Ltd. SeoulRepublic of Korea Soft Foundry Seoul National UniversitySeoulRepublic of Korea Department of Materials Science and Engineering Research Institute of Advanced MaterialsSchool of Chemical and Biological EngineeringInstitute of Engineering ResearchSeoul National UniversitySeoulRepublic of Korea

Perovskite light emitters can realize bright,stable and efficient light-emitting diodes through a molecular design strategy that enables strong endurance on high-current operation.

关键词： emitter light diodes

Severity of ultrasonographic liver steatosis and metabolic syndrome in Korean men and women

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World Journal of Gastroenterology 2005年第34期11卷 5314-5321页

作者： Hyeon Chang Kim sung Hee Choi Hae Won Shin Jae Youn Cheong Kwan Woo lee Hyun Chul lee Kap Bum Huh dae Jung Kim Department of Preventive Medicine Yonsei University College of Medicine Seoul South Korea Department of Internal Medicine Seoul National University College of Medicine Seongnam South Korea Department of Public Health Graduate School of Yonsei University Seoul South Korea Department of Gastroenterology Ajou University School of Medicine Suwon South Korea Department of Endocrinology and Metabolism Ajou University School of Medicine Suwon South Korea Department of Internal Medicine Yonsei University College of Medicine Seoul South Korea Huh's Diabetes Center and the 21~(st) Century Diabetes and Vascular Research Institute Seoul South Korea

AIM：To evaluate the association between the severity of liver steatosis and metabolic syndrome in apparently healthy Korean adults. METHODS： We examined 1022 men and women, aged 30-79 years, who participated in a health screening test. A standard interview, anthropometrics, biochemical studies, and abdominal ultrasonography were conducted for each participant. Metabolic syndrome was defined according to the National Cholesterol Education Program Adult Treatment Panel Ⅲ, with a modification for the waist circumference cut-off level. The severity of liver steatosis was evaluated using liver ultrasonography, and serum aspartate aminotransferase（AST）, alanine aminotransferase （ALT）, and γ-glutamyl transferase （γ-GT） levels were determined. RESULTS： Ultrasonographic liver steatosis was strongly associated with metabolic syndrome and common metabolic abnormalities. Compared with people without steatosis, people with mild, moderate, and severe steatosis had adjusted odds ratios for metabolic syndrome of 2.72 （95% CI, 1.01-2.94）, 2.89 （1.75-4.76） and 3.53 （1.25-9.98） in men, and 2.86 （1.64-5.01）, 3.19 （1.80-5.65） and 3.70 （0.82-16.73） in women, respectively. The serum AST level was not associated with metabolic syndrome. The serum ALT and γ-GT levels were significantly associated with metabolic syndrome in men but not in women.CONCLUSION： The occurrence of metabolic syndrome shows a stronger association with the severity of ultrasonographic steatosis than with the serum liver enzyme levels. The degree of fatty infiltration detected on ultrasonography can be used as an indicator of liver dysfunction attributable to metabolic abnormalities.

关键词： Metabolic syndrome Liver steatosis Nonalcoholic fatty liver disease Ultrasonography

Decomposing class responsibilities using distance-based method similarity

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Frontiers of Computer Science 2016年第4期10卷 612-630页

作者： Junha lee dae-Kyoo KIM Suntae KIM Sooyong PARK Department of Electronic and Computer Engineering Oakland University Rochester M148309 USA Department of Computer Science and Engineering Oakland University Rochester M148309 USA Department of Software Engineering Chonbuk National University Chonju 561-756 South Korea Department of Computer Science and Engineering Sogang University Seoul 121-741 South Korea

Cohesion is a design quality that has a great im- pact on the posterior development and maintenance. As software evolves, the cohesion of the system becomes weaker due to the changes introduced during evolution. Over evolution, a single responsibility class may be unintentionally assigned other responsibilities, which makes the class less cohesive and more complex and consequently increases the complexity of the entire system. There has been much work on decomposing class responsibilities based on internal class relationships such as method-attribute referencing and internal method calls. However, object-oriented systems involve significant external class relationships carrying important behavioral semantics, which should be taken into account in identifying class responsibilities. In this paper, we present a novel approach for identifying and decomposing classes responsibilities based on method similarity using both internal and external class relationships. We extend the existing work for measuring similarity of internal class relationships and present a distance-based method for measuring external class relationships. We evaluate the approach using three open source applications -- JMeter, JHotDraw, and ArgoUML. The evaluation shows that the presented approach improves precision over the existing work. We validate the results using independent samples T-test and ANOVA applied to a set of hypotheses. The validation confirms that the results are statistically significant.

关键词： class decomposition cohesion external rela-tionships identifying responsibility method similarity

Effects of surface roughness on bending properties of rolled AZ31 alloy

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Journal of Magnesium and Alloys 2023年第4期11卷 1224-1235页

作者： Gyo Myeong lee Jong Un lee sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

This study investigated the effects of mechanical-polishing-induced surface roughness and the direction of polishing lines on the bending properties of a rolled AZ31 *** this end,three-point bending tests were performed on one sample without polishing lines(SS sample)and two samples with polishing lines—one in which the polishing lines were parallel to the rolling direction(RS-RD sample)and the other in which they were parallel to the transverse direction(RS-TD sample).In all three samples,macrocracks were formed in the width direction on the outer surface,where tensile stress was predominantly generated in the longitudinal ***,the macrocracks formed in the SS sample were curved because of the merging of uniformly formed fine microcracks,whereas those formed in the RS-TD sample were linear owing to the formation of relatively coarse microcracks along the polishing *** bendability of the samples was in the order of SS>RS-RD>RS-TD,and their limiting bending depths were 4.8,4.6,and 4.4 mm,*** the presence of mechanical-polishing-induced surface roughness,polishing lines perpendicular to the direction of the major stress(i.e.,tensile stress along the longitudinal direction)resulted in a greater degree of stress concentration on the outer surface of the bending *** higher stress concentration promoted the formation of undesirable{10–11}contraction and{10–11}–{10–12}double twins—which typically act as crack initiation sites—and thereby facilitated crack generation and ***,the surface roughness caused premature fracture during bending deformation,which,in turn,caused deterioration of the bendability of the rolled Mg alloy.

关键词： AZ31 alloy Bending Surface roughness Stress concentration Crack

Bending properties of extruded AZ91–0.9Ca–0.6Y alloy and their improvement through precompression and annealing

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Journal of Magnesium and Alloys 2022年第8期10卷 2238-2251页

作者： Jong Un lee Gyo Myeong lee sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

In this study,an extruded Mg–9Al–1Zn–0.3Mn–0.9Ca–0.6Y(AZXW9110)alloy is subjected to precompression and subsequent annealing(PCA)treatment for improving its bending formability,and the three-point bending properties of the as-extruded material and the precompressed and subsequently annealed(PCAed)material at room temperature are *** bending,microcracks formed in undissolved Al2Ca,Al2Y,and Al8Mn4Y particles propagate along the grain boundaries or twin boundaries and consequently form a macrocrack in the tension zones of the bending samples of both the ***,the bending formability of the PCAed material is 75%higher than that of the as-extruded material owing to the promoted twinning and slip behaviors in the *** as-extruded material has a strong normal direction(ND)texture and a weak transverse direction(TD)texture,and the ND-and TD-oriented grains are unfavorable for both{10–12}twinning and basal slip in the tension zone of the bending sample of this material,which eventually results in its low bending *** PCAed material has a strong extrusion direction(ED)texture,weak TD texture,and spread ND *** bending,{10–12}twins are fully formed in the ED-oriented grains,and this{10–12}twinning effectively accommodates the plastic strain in the tension *** addition,the activation of basal slip in the ND-oriented grains of the PCAed material is promoted owing to the spread ND texture of this ***,this material exhibits substantially superior bending formability because of the vigorous{10–12}twinning in its ED-oriented grains and promoted basal slip in its ND-oriented grains.

关键词： Magnesium Bending Formability Twinning Texture

Redox-sensitive colorimetric polyaniline nanoprobes synthesized by a solvent=shift process

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Nano Research 2013年第5期6卷 356-364页

作者： Jihye Choi Yoochan Hong Eugene lee Myeong-Hoon Kim dae sung Yoon Jinsuck Suh Yongmin Huh Seungjoo Haam Jaemoon Yang Department of Chemical and Biomolecular Engineering Yonsei University Seou1120-749 Republic of Korea Department of Biomedical Engineering Yonsei University Wonju 220-710 Republic of Korea epartment of Radiology College of Medicine Yonsei University Seou1120- 752 Republic of Korea YUHS-KRIBB Medical Convergence Research Institute Seou1120-752 Republic of Korea Severance Biomedical Science Institute (SBSI) Seou1120-752 Republic of Korea Severance Integrative Research Institute for Cerebral and Cardiovascular Diseases Yonsei University Health System Seou1120-752 Republic of Korea

We have synthesized water-stable polyaniline nanoparticles coated with tri- armed polyethylene glycol chains using a solvent-shift method and confirmed their colloidal size and aqueous solubility. Furthermore, we have demonstrated that the polyaniline nanoparticles can be doped with biological dopants to produce distinct color changes allowing the detection of live cancer cells.

关键词： polyaniline solvent-shifting cancer colorimetric nanoprobe