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Journal of Magnesium and Alloys 2021年第5期9卷 1661-1672页

作者： Tae-hyuk lee Toru h.Okabe Jin-Young lee Young Min Kim Jungshin Kang Korea Institute of Geoscience and Mineral Resources 124 Gwahak-ro Yuseong-guDaejeon 34132Republic of Korea Institute of Industrial Science The University of Tokyo4-6-1 KomabaMeguro-kuTokyo 153-8505Japan University of Science and Technology 217 Gajeong-ro Yuseong-guDaejeon 34113Republic of Korea Korea Institute of Materials Science 797 Changwondae-roSeongsan-guChangwonGyeongnam51508Republic of Korea

The current electrolytic processes for magnesium(Mg)metal have several disadvantages,such as anhydrous magnesium chloride(MgCl_(2))preparation and generation of harmful chlorine(Cl_(2))*** overcome these drawbacks,a novel Mg production process to produce high-purity Mg metal directly from magnesium oxide(MgO)was investigated in this *** electrolysis of MgO was conducted using a liquid tin(Sn)cathode and a carbon(C)anode in the eutectic composition of a magnesium fluoride(MgF_(2))-lithium fluoride(LiF)molten salt under an applied voltage of 2.5 V at 1053-1113 *** certain conditions,the Mg-Sn alloys with Mg_(2)Sn and Mg(Sn)phases were obtained with a current efficiency of 86.6%at 1053 *** produce high-purity Mg metal from the Mg-Sn alloy,vacuum distillation was conducted at 1200-1300 K for a duration of 5-10 *** the vacuum distillation,the concentration of Mg in the Mg-Sn alloy feed decreased from 34.1 to 0.17 mass%,and Mg metal with a purity of 99.999%was obtained at 1200 ***,the electrolytic process developed here is feasible for the production of high-purity Mg metal from MgO using an efficient method.

关键词： Magnesium Magnesium oxide Electrolytic process Liquid tin cathode Vacuum distillation

Scale dependence of direct shear tests

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Chinese Science Bulletin 2009年第23期54卷 4337-4348页

作者： ZhOU Qiang ShEN hayley h hELENBROOK brian T ZhANG hongWu Department of Engineering Mechanics Dalian University of Technology Dalian 116024 China Department of Civil and Environmental Engineering Clarkson University Potsdam NY 13699-5710 USA Department of Mechanical and Aeronautical Engineering Clarkson University Potsdam NY 13699-5725 USA

Direct shear test has been widely used to measure the shear strength of soils and other particulate materials in industry because of its simplicity. however, the results can be dependent on the specimen size. The ASTM (American Society for Testing and Materials) publications suggest that for testing soils the shear box should be at least ten times the diameter of the largest particle and the height of the box should be no more than half of its diameter. These guidelines are empirically based. A series of two-dimensional numerical direct shear tests are performed to investigate this scaling effect. By analyzing the bulk friction, particle translation and rotation, percentage of sliding, average volume (area) and shear strain and the evolution of the shear band, we find that the traditional guidelines for direct shear tests are questionable. Scaling dependency of bulk friction on the property of granular materials is clearly present. Our current analysis points out that the scaling effects can vary significantly depending on the particle properties other than their sizes. Of all the parameters we observed, particle rotation appears to have a decisive correlation with the bulk friction. Formation of a shear band is universal. As the shearing progresses, particle rotation begins to concentrate near the shear plane. By defining the width of a shear band as the standard deviation of the distribution of translational gradient or the standard deviation of the distribution of particle rotation, quantitative evolutions of shear band are presented. Both measures of the shear band width dropped rapidly during pre-failure stage. After peak stress both measures begin to approach steady state as the bulk friction stabilizes to the residual stage. These observations suggest that structure formation inside the shear band controls the scaling effect.

关键词：直接剪切试验测试土力学土工试验

What Causes the Springtime Tropospheric Ozone Maximum over Northeast Asia?

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Advances in Atmospheric Sciences 2010年第3期27卷 543-551页

作者： Jae h.KIM hyunjin lee Department of Atmospheric Science Pusan National University

Scientists have long debated the relative importance of tropospheric photochemical production versus stratospheric influx as causes of the springtime tropospheric ozone maximum over northern mid-latitudes. This paper investigates whether or not stratospheric intrusion and photochemistry play a significant role in the springtime ozone maximum over Northeast Asia, where ozone measurements are sparse. We examine how tropospheric ozone seasonalities over Naha （26°N, 128°E）, Kagoshima （31°N, 131°E）, and Pohang （36°N, 129°E）, which are located on the same meridional line, are related to the timing and location of the jet stream. The ozone seasonality shows a gradual increase from January to the maximum ozone month, which corresponds to April at Naha, May at Kagoshima, and June at Pohang. In order to examine the occurrence of stratospheric intrusion, we analyze a correlation between jet stream activity and tropospheric ozone seasonality. From these analyses, we did not find any favorable evidence supporting the hypothesis that the springtime enhancement may result from stratospheric intrusion. According to trajectory analysis for vertical and horizontal origins of the airmass, a gradual increasing tendency in ozone amounts from January until the onset of monsoon was similar to the increasing ozone formation tendency from winter to spring over China's Mainland, which has been observed during the build-up of tropospheric ozone over Central Europe in the winter-spring transition period due to photochemistry. Overall, the analyses suggest that photochemistry is the most important contributor to observed ozone seasonality over Northeast Asia.

关键词： tropospheric ozone photochemistry, stratospheric intrusion, jet stream activity, trajectory

Computational study on influence of RF shielding box on inductance of coil

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Plasma Science and Technology 2019年第6期21卷 23-28页

作者： S J KIM J J lee Y S lee J h KIM S J YOU Applied Physics lab for PLasma Engineering(APPLE) Department of Physics Chungnam National University Daejeon 34134 Republic of Korea Korea Research Institute of Standards and Science(KRISS) Daejeon 34113 Republic of Korea

Despite the fact that a radio frequency (RF) shielding box affects a coil inductance used in matching network,RF engineers have used a coil inductance measured in open space on designing matching networks since it is difficult to precisely measure the coil inductance within the RF shielding *** this work,we investigate the influences of the RF shielding box on the coil inductance via a 3D full electromagnetic wave *** results shows that the coil inductance decreases from-6.0% to-11.9% compared with its ideal inductance depending on coil positions within the RF shielding *** inductive and capacitive coupling between the coil and surfaces of the RF shielding box contribute to the reduction of the coil *** expect that these results would be useful for those who design RF matching networks.

关键词： 3D full EM wave simulation RF matching component RF shield inductive and capacitive coupling

C_2h_2-2.5O_2-Ar混合气体临界管径和爆轰胞格及临界能量的实验研究

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北京理工大学学报 2012年第3期32卷 226-230页

作者：张博白春华 John h.S.lee 北京理工大学爆炸科学与技术国家重点实验室北京100081 Department of Mechanical Engineering McGill University

建立了C2h2-2.5O2-Ar混合气体爆轰临界管径的测试系统,其中高压电火花作为起爆源.首先分别测定了C2h2-2.5O2,C2h2-2.5O2-50%Ar,C2h2-2.5O2-70%Ar三种混合气体在不同初始压力下的爆轰临界管径.结果表明:随着氩气稀释浓度的提高,在管道直... 详细信息

建立了C2h2-2.5O2-Ar混合气体爆轰临界管径的测试系统,其中高压电火花作为起爆源.首先分别测定了C2h2-2.5O2,C2h2-2.5O2-50%Ar,C2h2-2.5O2-70%Ar三种混合气体在不同初始压力下的爆轰临界管径.结果表明:随着氩气稀释浓度的提高,在管道直径相同的条件下,可形成球形爆轰的临界压力增加,表明物质的爆轰敏感性降低.进一步探究各种物质临界管径与爆轰胞格的关系,得到了三种物质临界管径与胞格宽度的比例系数.最后分析了三种物质的临界管径和直接起爆的临界能量的关联性,并与lee表面积能量模型对比,实验结果与理论模型基本吻合,得出C2h2-2.5O2-Ar混合气体爆轰临界管径与临界起爆能量之间的关系为Ec=16-1πρ0v2CJIdc3.

关键词：爆轰临界管径胞格宽度临界能量电火花点火

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Summary

Chinese Physics C 2009年第12期33卷 1230-1232页

作者： T.-S. h. lee Physics Division Argonne National Laboratory Argonne IL 60439 USA Excited Baryon Analysis Center (EBAC) Thomas Jefferson National Accelerator Facility Newport News VA 23606 USA

A summary of the contributions to this workshop is given. The status and future development of N＊ physics are discussed.

关键词： PWA resonance

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Journal of Central South University 2009年第5期16卷 789-793页

作者： KIM J h.lee S h 王洪梅 School of Mechatronics Changwon National University 9 Sarim-dong Changwon Gyeongnam 641-773 Korea

Fault detection technique is introduced with similarity measure. The characteristics of conventional similarity measure based on fuzzy number are discussed. With the help of distance measure, similarity measure is constructed explicitly. The designed distance-based similarity measure is applicable to general fuzzy membership functions including non-convex fuzzy membership function, whereas fuzzy number-based similarity measure has limitation to calculate the similarity of general fuzzy membership functions. The applicability of the proposed similarity measure to general fuzzy membership structures is proven by identifying the definition. To decide fault detection of flight system, the experimental data （pitching moment coefficients and lift coefficients） are transformed into fuzzy membership functions. Distance-based similarity measure is applied to the obtained fuzzy membership functions, and similarity computation and analysis are obtained with the fault and normal operation coefficients.

关键词： similarity measure fuzzy number, distance non-convex membership function

Efficient photovoltaic effect in graphene/h-BN/silicon heterostructure self-powered photodetector

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Nano Research 2021年第6期14卷 1967-1972页

作者： Ui Yeon Won Boo heung lee Young Rae Kim Won Tae Kang Ilmin lee Ji Eun Kim Young hee lee Woo Jong Yu Department of Electrical and Computer Engineering Sungkyunkwan UniversitySuwon16419Republic of Korea Center for Integrated Nanostructure Physics Institute for Basic Science(IBS)Suwon16419Republic of Korea

Graphene(Gr)/Si-based optoelectronic devices have attracted a lot of academic attention due to the simpler fabrication processes,low costs,and higher performance of their two-dimensional(2D)/three-dimensional(3D)hybrid interfaces in Schottky junction that promotes electron-hole ***,due to the built-in potential of Gr/Si as a photodetector,the Iph/Idark ratio is often hindered near zero-bias at relatively low illumination *** is a major drawback in self-powered *** this study,we have demonstrated a self-powered van der Waals heterostructure photodetector in the visible range using a Gr/hexagonal boron nitride(h-BN)/Si structure and clarified that the thin h-BN insertion can engineer asymmetric carrier transport and avoid interlayer coupling at the *** dark current was able to be suppressed by inserting an h-BN insulator layer,while maintaining the photocurrent with minimal decrease at near *** a result,the normalized photocurrent-to-dark ratio(NPDR)is improved more than 104 ***,both Iph/Idark ratio and detectivity,increase by more than 104 times at−0.03 V drain *** proposed Gr/h-BN/Si heterostructure is able to contribute to the introduction of next-generation photodetectors and photovoltaic devices based on graphene or silicon.

关键词： graphene hexagonal boron nitride van der Waals heterostructure self-powered Research

Effect of Reactivity of Quick Lime on the Properties of hydrated Lime Sorbent for SO_2 Removal

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Journal of Materials Science & Technology 2009年第3期25卷 329-332页

作者： h.G. Shin h. Kim Y.N. Kim h.S. lee Department of Materials Science and Engineering Seoul National University Material Analysis Team Korea Testing Laboratory School of Materials Science and Engineering Pusan National University

The hydration of quick lime and the sulfation of hydrated lime were carried out for verification of relationship between the reactivity of quick lime and the properties of hydrated lime as a sorbent. The effect of reactivity of quick lime was investigated with the change of calcination temperature and time. Results obtained showed that the temperature rise during the hydration of quick limes varied from 31 to 69℃ with the variation of calcination temperature and time. The specific surface area and the sulfation ability of hydrated lime prepared by hydration of quick lime showed a proportional relationship with the reactivity of quick lime. The hydrated lime which was prepared by hydration of quick lime calcined at 1100℃ had the highest reactivity and showed 41.53 m^2/g of the specific surface area, 0.16 cm^3/g of the pore volume and 87% of the removal efficiency for SO2 removal,

关键词： Reactivity Quick lime hydrated lime Calcination hydration Sorbent

Numerical Experiment on Two-Dimensional Line Thermal

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China Ocean Engineering 2002年第4期17卷 453-467页

作者： J.h.W.lee 陈国谦 Department of Civil Engineering University of Hong KongHongkongChina National Laboratory for Turbulence Peking UniversityBeijing 100871China

The time evolution of a two-dimensional line thermal-a turbulent flow produced by an initial element with significant buoyancy released in a large water body, is numerically studied with the two-equation k - epsilon model for turbulence closure. The numerical results show that the thermal is characterized by a vortex pair flow and a kidney shaped concentration structure with double peak maxima; the computed flow details and scalar mixing characteristics can be described by self-similar relations beyond a dimensionless time around 10. There are two regions in the flow field of a line thermal: a mixing region where the concentration of tracer fluid is high and the flow is turbulent and rotational with a pair of vortex eyes, and an ambient region where the concentration is zero and the flow is potential and well-described by a model of doublet with strength very close to those given by early experimental and analytical studies. The added virtual mass coefficient of the thermal motion is found to be approximately 1. The aspect ratio for the kidney-shaped sectional thermal is found to be around 1.45 for the self-similar phase. The predicted thermal spreading and mixing rate compares well with experimental data.

关键词： thermals and puffs turbulence modeling plumes and jets environmental fluid mechanics vortex flow added virtual mass mixing and transport