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Effects of design parameters and tension on behavior of a coil using finite element analysis

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Journal of Iron and Steel Research International 2018年第9期25卷 883-891页

作者： Kyu-tae ParkI Hyun-chul Park Department of Mechanical Engineering Pohang Universityof Science and Technology Pohang Gyeongbuk 790-784Korea

During the thin strip coiling process, it is necessary to use a sleeve with a mandrel to prevent excessive deformation of the strip. Stress distribution in the sleeve and in the strip is an important factor that determines the quality of the coil. However, owing to the accumulation of high pressure, it is difficult to determine the stress distribution through experimentation. Thus, stress analysis of the strip coiling process was conducted. Finite element analysis was used to investigate the effects of the weight of the strip and the mandrel on the stress distribution and stress concentration near the starting point of the coil. The radial stress was predicted for a coil with a stacked thickness of 384 mm, which corresponds to a strip length of 1486 m, using the stress analysis model developed in a preceding research. A method was presented to reduce the weight and radial stress of a strip coil. It was found that the deformation of the sleeve can be reduced by decreasing the gap between the mandrel segments. The thickness of the sleeve can be reduced from 120 to 106 mm using the stress analysis results. Furthermore, coiling tension can be reduced by 44% compared to the existing value considering the interlayer slip of the strip coil.

关键词： Strip coiling process Structural analysis Finite element method Mandrel Coiling tension

Comparative pollen morphology of Glechoma and Marmoritis(Nepetinae,Lamiaceae)

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Journal of Systematics and Evolution 2010年第6期48卷 464-473页

作者： tae-Soo JANG Suk-Pyo HONG Laboratory of Plant Systematics Department of BiologyInstitute of Basic SciencesKyung Hee University

The pollen morphology of 13 taxa(34 specimens) of the genera Glechoma L.,and Marmoritis *** investigated in detail using light,scanning electron,and transmission electron *** grains of all studied taxa are small to large in size(P = 32.5-60.4 μm,E = 20.2-50.5 μm),prolate-spheroidal to prolate in shape and mostly hexacolpate(the amb more or less circular or rarely ellipsoid) with granular *** sexine ornamentation of Glechoma is bireticulate;the muri of the primary reticulum are irregularly circled,and lumen size is *** contrast,the sexine surfaces of the Marmoritis pollen tend to more elongate or wider at the muri of the primary reticulum than those of the *** pollen wall stratification of selected taxa(three from Glechoma and one from Marmoritis) is characterized by unbranched columellae,and continuous or distinctly discontinuous endexine based on transmission electron microscopy *** results of Glechoma and Marmoritis reveal rather similar pollen morphological features,however,fine details of sexine ornamentation are characteristic to differentiate the pollen *** these differences may be useful in establishing the taxonomic boundary between two genera,they are too weak to segregate diagnostic characters.

关键词： Glechoma Lamiaceae Marmoritis Nepetinae pollen morphology scanning electron microscope sexine ornamentation transmission electron microscope.

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

Chemopreventive drugs:Mechanisms via inhibition of cancer stem cells in colorectal cancer

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World Journal of Gastroenterology 2014年第14期20卷 3835-3846页

作者： tae Il Kim Department of Internal Medicine and Institute of Gastroenterology Yonsei University College of Medicine

Recent epidemiological studies,basic research and clinical trials on colorectal cancer(CRC)prevention have helped identify candidates for effective chemopreventive ***,because of the conflicting results of clinical trials or side effects,the effective use of chemopreventive drugs has not been generalized,except for patients with a high-risk for developing hereditary *** in genetic and molecular technologies have highlighted the greater complexity of carcinogenesis,especially the heterogeneity of *** need to target cells and processes that are critical to carcinogenesis for chemoprevention and treatment of advanced *** research has shown that intestinal stem cells may serve an important role in tumor initiation and formation of cancer stem ***,studies have shown that the tumor microenvironment may play additional roles in dedifferentiation,to enable tumor cells to take on stem cell features and promote the formation of tumorigenic stem ***,early tumorigenic changes of stem cells and signals for dedifferentiation may be good targets for *** this review,I focus on cancer stem cells in colorectal carcinogenesis and the effect of major chemopreventive drugs on stem cell-related pathways.

关键词： Colorectal cancer Chemoprevention Cancer stem cell Carcinogenesis Microenvironment

An efficient method for tracing planar implicit curves

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第7期7卷 1115-1123页

作者： YU Zheng-sheng CAI Yao-zhi oh Min-jae KIM tae-wan PENG Qun-sheng Computer Science School Hangzhou Dianzi University Hangzhou 310018 China Department of Naval Architecture and Ocean Engineering Seoul National University Seoul 151-744 Korea Applied Mathematics Department Zhejiang University Hangzhou 310027 China State Key Laboratory of CAD ＆ CG Zhejiang University Hangzhou 310027 China

This paper presents a method for tracing a planar implicit curve f（x, y）=0 on a rectangular region based on continuation scheme. First, according to the starting track-point and the starting track-direction of the curve, make a new fimction F（x, y）=0 where the same curve withf（x, y）=0 is defined. Then we trace the curve between the two domains where F（x, y）〉0 and F（x, y）〈0 alternately, according to the two rules presented in this paper. Equal step size or adaptive step size can be used, when we trace the curve. An irregular planar implicit curve （such as the curve with large curvatures at some points on the curve）, can be plotted if an adaptive step size is used. Moreover, this paper presents a scheme to search for the multiple points on the curve. Our method has the following advantages：（1） it can plot Co planar implicit curves; （2） it can plot the planar implicit curves with multiple points; （3） by the help of using the two rules, our method does not need to compute the tangent vector at the points on the curve, and directly searches for the direction of the tracing curve; （4） the tracing procedure costs only one of two evaluations of function f（x, y）=0 per moving step, while most existing similar methods cost more evaluations of the function.

关键词： Planar implicit curve Curve tracing Continuation method Geometric modeling

Evaluation of Simulated CO_2 Concentrations from the CarbonTracker-Asia Model Using In-situ Observations over East Asia for 2009–2013

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Advances in Atmospheric Sciences 2019年第6期36卷 603-613页

作者： Samuel Takele KENEA Young-Suk oh Jae-Sang RHEE tae-Young GOO Young-Hwa BYUN Shanlan LI Lev D.LABZOVSKII Haeyoung LEE Robert F.BANKS Climate Research Division National Institute of Meteorological Sciences Environmental Meteorology Research Division National Institute of Meteorological Sciences Meteorology Department Delta Air LinesInc.

The CarbonTracker(CT) model has been used in previous studies for understanding and predicting the sources, sinks, and dynamics that govern the distribution of atmospheric CO_2 at varying ranges of spatial and temporal scales. However, there are still challenges for reproducing accurate model-simulated CO_2 concentrations close to the surface, typically associated with high spatial heterogeneity and land cover. In the present study, we evaluated the performance of nested-grid CT model simulations of CO_2 based on the CT2016 version through comparison with in-situ observations over East Asia covering the period 2009–13. We selected sites located in coastal, remote, inland, and mountain areas. The results are presented at diurnal and seasonal time periods. At target stations, model agreement with in-situ observations was varied in capturing the diurnal cycle. Overall, biases were less than 6.3 ppm on an all-hourly mean basis, and this was further reduced to a maximum of 4.6 ppm when considering only the daytime. For instance, at Anmyeondo, a small bias was obtained in winter, on the order of 0.2 ppm. The model revealed a diurnal amplitude of CO_2 that was nearly flat in winter at Gosan and Anmyeondo stations, while slightly overestimated in the summertime. The model's performance in reproducing the diurnal cycle remains a challenge and requires improvement. The model showed better agreement with the observations in capturing the seasonal variations of CO_2 during daytime at most sites, with a correlation coefficient ranging from 0.70 to 0.99. Also, model biases were within-0.3 and 1.3 ppm, except for inland stations(7.7 ppm).

关键词： model evaluation in-situ observations CarbonTracker East Asia

A Tracing Algorithm for Surface—Surface Intersections on Surface Boundaries

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Journal of Computer Science & Technology 2002年第6期17卷 843-850页

作者： Kyu－YeulLee tae－WanKim 等 DepartmentofNavalArchitectureandOceanEngineeringandResearchInstituteofMarineSystemEngineering SeoulNationalUniversitySan56－1Shillim－DongKwanak－GuSeoul151－742Korea Departmentof

In this paper we present an algorithm with a new trace-terminating conditionfor tracing along surface-surface intersection curves on surface boundaries, while several tracingmethods and embedding methods that include tracing scheme may cause false termination with atraditional trace-terminating condition: tracing stops when the surface-domain's boundary isreached. And we also suggest another iterative method to calculate intersection points on surfaceboundaries with parallel surface normal. Some numerical examples with these two ideas andcomparisons to 'DESIGNBASE', 'ACIS', and 'Parasolid' are included to demonstrate the effectivenessof our algorithm.

关键词： surface-surface intersection tracing method surface boundary trace-terminating condition

Plasma levels of acylated ghrelin in patients with functional dyspepsia

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World Journal of Gastroenterology 2012年第18期18卷 2231-2237页

作者： Yeon Soo Kim Joon Seong Lee tae Hee Lee Joo Young Cho Jin oh Kim Wan Jung Kim Hyun Gun Kim Seong Ran Jeon Hoe Su Jeong Department of Internal Medicine Hallym University College of MedicineChuncheon Sacred Heart HospitalGangwon-do 200-704South Korea Department of Internal Medicine Soonchunhyang University College of MedicineSoonchunhyang University HospitalSeoul 140-743South Korea Department of Anatomy and Cell Biology Hanyang University College of Medicine222 Wangsimni-roSeongdong-guSeoul 133-792South Korea

AIM:To investigate the relationship between plasma acylated ghrelin levels and the pathophysiology of functional ***:Twenty-two female patients with functional dyspepsia and twelve healthy volunteers were recruited for the *** functional dyspepsia patients were each diagnosed based on the Rome Ⅲ *** patients completed a questionnaire concerning the severity of 10 *** acylated ghrelin levels before and after a meal were determined in the study participants using a commercial human acylated enzyme immunoassay kit;electrogastrograms were performed for 50 min before and after a standardized 10-min meal containing 265 ***:There were no significant differences in plasma acylated ghrelin levels between healthy volunteers and patients with functional ***,in patients with functional dyspepsia,there was a negative correlation between fasting plasma acylated ghrelin levels and the sum score of epigastric pain(r =-0.427,P = 0.047) and a positive correlation between the postprandial/fasting plasma acylated ghrelin ratio and the sum score of early satiety(r = 0.428,P =0.047).Additionally,there was a negative correlation between fasting acylated ghrelin plasma levels and fasting normogastria(%)(r =-0.522,P = 0.013).Interestingly,two functional dyspepsia patients showed paradoxically elevated plasma acylated ghrelin levels after the ***:Abnormal plasma acylated ghrelin levels before or after a meal may be related to several of the dyspeptic symptoms seen in patients with functional dyspepsia.

关键词： Functional dyspepsia Acylated ghrelin Electrogastrogram Rome Ⅲ criteria Dyspeptic symptoms

Effects of Hub-To-Tip Ratio and Tip Clearance on Hysteretic Characteristics of Wells Turbine for Wave Power Conversion

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Journal of Thermal Science 2002年第3期11卷 207-213页

作者： tae-HoKim YoichiKinoue ToshiakiSetoguchi KenjiKaneko Department of Mechanical Engineering Saga University Saga Japan

A Wells turbine for wave power conversion has hysteretic characteristics in a reciprocating flow. The hysteretic loop is opposite to the well-known dynamic stall of an airfoil. In this paper, the mechanism of the hysteretic behavior was elucidated by an unsteady 3-dimensional Navier-Stokes numerical simulation. It was found that the hysteretic behavior was associated with a streamwise vortical flow appearing near the blade suction surface. The effects of hub-to-tip ratio and tip clearance on the hysteretic characteristics of the Wells turbine have also been discussed in this paper.

关键词： Turbomachinery Wells turbine natural energy ocean wave energy wave power conversion