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Effect of Si Content on Mechanical Properties of a Mo and V Free Low Alloy Cast Steel for Automobile Cold Pressing Die

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Journal of Materials Science & Technology 2008年第3期24卷 313-316页

作者： B.h.kim J.S.Shin S.M.Lee B.M.Moon h.D.kim S.Y.Ju O.Y.Choi Advanced Materials R＆D Division Korea Institute of Industrial Technology Incheon 406-840 Korea Tooling Center GM Daewoo Auto ＆ Technology Co. Incheon 403-714 Korea

The effects of Si content on combinations of important properties such as hardness, hardenability, and weldability in addition to strength increment were systematically investigated to develop a Mo and V free low alloy cast steel for automobile cold pressing die insert. For the evaluation of the applicability as the die insert, the mechanical properties were measured after spheroidization annealing （SA）, quenching and tempering （Q/T）, and flame hardening （Fh） treatments, respectively. The developed 0.8%-1.6%Si containing Mo and V free alloy cast steels showed excellent matrix strengthening effect, hardenability, and weldability, fulfilling the industrial criterion of the mechanical properties for the die insert.

关键词： Low alloy cast steel Cold pressing die Die insert Matrix hardening Flame hardening

Evaluation of Rice Seedling Tolerance to Constant and Intermittent Low Temperature Stress

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Rice science 2012年第4期19卷 295-308页

作者： Sang-Ic kim Dong-min kim Thomas h.TAI USDA-ARS Crops Pathology and Genetics Research Unit Department of Plant Sciences-Mail Stop 1University of CaliforniaDavisCA 95616USA Department of Agronomy Chungnam National UniversityDaejeon 305-764Republic of Korea

M202, IR50 and advanced backcross （BC4F6） lines carrying the cold tolerance QTLs qCTS4 and qCTS12 were evaluated using three low temperature stress assays （constant, intermittent and constant with recovery period）. Under constant stress, two BC4F6 lines （MIb 4853-9 and MIb 6885-2） exhibited differences in seedling growth and accumulation of stress-related compounds although both carry the two QTLs in the IRS0 background. Differences between these lines were also observed in the constant with recovery period assay, although both of them performed comparably under intermittent stress, MIb 6885-2 performed more similarly to M202 in the constant and constant with recovery period assays, suggesting that this line contains an introgressed region（s） not present in MIb 4853-9. The three assays were also applied to assess variations in cold tolerance in a set of diverse germplasms. Performance metrics and visual ratings were comparable for evaluating tolerance to constant stress. however, differences in response to intermittent stress were more evident from growth and total chlorophyll measurements than from visual ratings. With regard to the constant with recovery period assay, about 15% of the germplasm accessions did not recover. however, some lines which exhibited chilling injuries of comparable severity were able to overcome them. This recovery phenotype may improve rice performance in the field and warrant further investigation.

关键词： rice seedling cold tolerance quantitative trait locus advanced backcross line low temperature stress

EFFECT OF CARBON AND BORON ON MICROSTRUCTURE AND MEChANICAL PROPERTIES OF A SINGLE CRYSTAL SUPERALLOY RR 2072

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Acta Metallurgica Sinica(English Letters) 2005年第1期18卷 33-38页

作者： D.h.kim D.h.Ye J.h.Lee Y.S.Yoo C.Y.Jo high Temperature Materials Laboratory korea Institute of Machinery&Materials 66 SangnamChangwonKyungnam 640-010S.Korea Dept.of Metallurgy Changwon National Univerisity 9 SarimChagwonKyungnam 640-773S.Korea

Carbon and boron have been considered to strengthen grain boundaries that might form during single crystal *** this study the effect of boron on solidification behavior and creep properties of the carbon doped single crystal RR 2072 has been *** order to understand solidification behavior with boron addition,the solid/liquid interface morphology and solidification microstructure were examined with solidification *** relationship between mi-crostructural evolution and creep properties of the carbon and boron modified single crystal has been also investigated.

关键词： single crystal superalloy defect tolerance directional solidification creep rupture

Optimization of casting conditions for heat and abrasion resistant large grey iron castings

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China Foundry 2007年第2期4卷 124-127页

作者： S. M. Yoo Y. S. Cho C. C. Lee J. h. kim C. h. kim J. k. Choi Center for e-Design Korea Institute of Industrial TechnologyYeonsugu Sondodong 7-47Incheon 406-800Korea kwanghee Casting Mfg. Co. Seogu Kyungseodong 381-75Incheon 404-170Korea R&D Center Doosan Engine Co. Ltd. Sinchondong 69-3 Changwon 641-370 Korea

Numerical simulation technology was applied for optimizing the casting design and conditions in large cast iron castings for marine engine. By the simulation of mold filling and solidification sequences the problems of the previous casting conditions were analyzed and marked improvements for large cylinder liner parts were derived from these results. Especially the amount and positions of chills were optimized to increase the mechanical properties and to minimize the shrinkage and microporosity in the castings. Ultrasonic testing, penetration testing and mechanical property testing were carried out for the parts with the modified casting conditions. It showed that no defects in the castings were found and the productivity could be distinctly increased. The mechanical properties satisfied also the specification demanded.

关键词： grey cast iron numerical simulation marine engine cylinder liner chill casting design optimization

A Study on the Gas-Solid Particle Flows in a Needle-Free Drug Delivery Device

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Journal of Thermal Science 2013年第4期22卷 340-344页

作者： Md.Alim Iftekhar Rasel Md.Abu Taher h.D.kim Department of Mechanical Engineering Andong National University

Different systems have been used over the years to deliver drug particles to the human skin for pharmaceutical effect. Research has been done to improve the performance and flexibility of these systems. In recent years a unique system called the transdermal drug delivery has been developed. Transdermal drug delivery opened a new door in the field of drug delivery as it is more flexible and offers better performance than the conventional systems. The principle of this system is to accelerate drug particles with a high speed gas flow. Among different transdermal drug delivery systems we will concentrate on the contour shock tube system in this paper. A contoured shock tube is consists of a rupture chamber, a shock tube and a supersonic nozzle section. The drug particles are retained between a set of bursting diaphragm. When the diaphragm is ruptured at a certain pressure, a high speed unsteady flow is initiated through the shock tube which accelerates the particles. Computational fluid dynamics is used to simulate and analyze the flow field. The DPM (discrete phase method) is used to model the particle flow. As an unsteady flow is initiated though the shock tube the drag correlation proposed by Igra et al is used other than the standard drag correlation. The particle velocities at different sections including the nozzle exit are investigated under different operating conditions. Static pressure histories in different sections in the shock tube are investigated to analyze the flow field. The important aspects of the gas and particle dynamics in the shock tube are discussed and analyzed in details.

关键词： Shock tube Drug delivery Contoured shock tube Unsteady flow Biolistics

Expanding the view of a standard colonoscope with the Third Eye~ Panoramic^(TM) cap

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World Journal of Gastroenterology 2015年第37期21卷 10683-10687页

作者： Moshe Rubin Leigh Lurie konika Bose Sang h kim New York Presbyterian-Queens Weill Cornell Medical College

AIM: To evaluate a new imaging device for colonoscopy that adds two side viewing CMOS lenses, the Third EyePanoramic. ***: In this prospective observational feasibility study, 33 patients, 18 male and 15 female, underwent routine screening, surveillance or diagnostic colonoscopy with the new Third EyePanoramic. cap clipped on to the distal tip of a high definition Fuji EC530-LS Slim Colonoscope. All procedures were performed at the New York Presbyterian-Queens Endoscopy unit by two experienced endoscopists(Rubin M and kim Sh). Main outcome measurements included evaluation of the image quality of the Third EyePanoramic. cap, adenoma detection rate, cecal intubation rate, withdrawal time and total procedure ***: The Third EyePanoramic. cap enabled enhanced views without affecting the quality of the colonoscope's image or its handling characteristics through the colon. Ileal intubation was accomplished in most cases, but was more challenging. The side view lenses detected polyps and diverticula hidden behind folds and in flexures not seen on the standard *** side view lenses were easily cleaned utilizing an EndogatorIrrigation Pump(Medivators, Minneapolis,MN, United States) by angling the scope tip against the mucosa while washing. The cecum was reached in all33 patients. Mean cecal intubation time was 8.19 ± 2.17 min, mean withdrawal time was 10.15 ± 5.56 min and mean total procedure time was 20.31 ± 5.14 min. The overall adenoma detection rate was 44%.CONCLUSION: The Third EyePanoramic. cap enables wide view colonoscopy with enhanced visualization utilizing standard forward view colonoscopes.

关键词： Colonoscopy Adenoma detection rate Endoscopic tech

Beta Gyres in Global Analysis Fields

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Advances in Atmospheric Sciences 2009年第5期26卷 984-994页

作者： Sun-hee kim h. Joe kWON R. L. ELSBERRY Department of Atmospheric Sciences/Typhoon Research Center Kongju National University Department of Meteorology Naval Postgraduate School

A three-component decomposition is applied to global analysis data to show the existence of a beta gyre, which causes Tropical Cyclone （TC） to drift from a large-scale environmental steering current. Analyses from the Global Data Assimilation and Prediction System （GDAPS） of the korea Meteorological Adminis- tration （kMA）, the Global Forecast System （GFS） of NCEP, and the Navy Operational Global Atmospheric Prediction System （NOGAPS） are used in this study. The structure of the beta gyre obtained in our analyses is in good agreement with the theoretical structure, with a cyclonic circulation to the southwest of the TC center, an anticyclonic circulation to the northeast, and a ventilation flow directed northwestward near the center. The circulation of the beta gyre is strongest at the 850-hPa level where the cyclonically swirling primary circulation is strongest, and decreases with height, in a pyramid shape similar to the primary circulation. The individual structure of the beta gyre is case- and model-dependent. At a certain analysis time, one model may clearly reveal a well-defined beta gyre, but the other models may not. Within one model, the beta gyre may be well defined at some analysis times, but not at other times. The structure of the beta gyre in the analysis field is determined by the nature of the vortex initialization scheme and the model behavior during the 6-h forecast in the operational data assimilation cycle.

关键词： tropical cyclone beta gyre GDAPS GFS NOGAPS TCM-90 final analyses

Transient analysis of diffusive chemical reactive species for couple stress fluid flow over vertical cylinder

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Applied Mathematics and Mechanics(English Edition) 2013年第8期34卷 985-1000页

作者： h.P.RANI G.J.REDDY C.N.kim Department of Mathematics National Institute of Technology Department of Mechanical Engineering College of Advanced Technology (Industrial Liaison Research Institute) Kyung Hee University

The unsteady natural convective couple stress fluid flow over a semi-infinite vertical cylinder is analyzed for the homogeneous first-order chemical reaction effect. The couple stress fluid flow model introduces the length dependent effect based on the material constant and dynamic viscosity. Also, it introduces the biharmonic operator in the Navier-Stokes equations, which is absent in the case of Newtonian fluids. The solution to the time-dependent non-linear and coupled governing equations is carried out with an unconditionally stable Crank-Nicolson type of numerical schemes. Numerical results for the transient flow variables, the average wall shear stress, the Nusselt number, and the Sherwood number are shown graphically for both generative and destructive reactions. The time to reach the temporal maximum increases as the reaction constant k increases. The average values of the wall shear stress and the heat transfer rate decrease as k increases, while increase with the increase in the Sherwood number.

关键词： couple stress fluid chemical reaction natural convection vertical cylinder,finite difference method

Anisotropic NdFeB Magnet Fabricated by Single Stroke hot Deformation

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Journal of Materials Science & Technology 2000年第2期16卷 129-130页

作者： Y.Li (Chungnam National University, Taejon, korea) Y.B.kim (korea Research Institute of Standards and Science, Taejon, korea) M.J.kim, M.S.Song, J.h.Yang, T.k.kim and C.O.kim (Chungnam National University, Taejon, korea) Chungnam National University Taejon South Korea korea Research Institute of Standards and Science Taejon South Korea

The general hot deformation process consists of two steps, hot pressing and die-upsetting in order to obtain the anisotropic NdFeB magnet. This is the first report that the high anisotropy NdFeB magnets can be fabricated by single stroke hot deforming the isotropic magnet. The magnetic properties of those materials are: coercivity ihc ～11 kOe, remanence Br ～12 kG, and the maximum energy product (Bh)max ～28 ***.

关键词： NdFeB Anisotropic NdFeB Magnet Fabricated by Single Stroke hot Deformation