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What Causes the Springtime Tropospheric Ozone Maximum over North.ast 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 North.ast 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 North.ast Asia.

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

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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

Deformation heterogeneity of Ti under cryogenic channel-die compression

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Progress in Natural Science:Materials International 2011年第4期21卷 277-285页

作者： K.h.kim S.K.h.aNG Division of Materials Science and Engineering Inha University

Commercial purity Ti was subjected to channel die compression in liquid nitrogen for the purpose of studying its deformation characteristics from the viewpoint of the grain refinement induced by severe plastic *** specimens showed microstructural heterogeneity in that the initial blocky grains of about 50 urn in size turned into a mixture of the easily deforming soft grains and the hard grains revealing local concentration of dislocations and deformation *** electron back scattered diffraction analysis the in-grain misorientation-axis distribution was studied,from which it was found that the deformation heterogeneity resulted from the anisotropy of individual grains with respect to the compression die:while the soft grains were those oriented favorably for the prismslip,the hard ones were oriented for non-prism slips and deformation *** difference in the response of individual grains,therefore,led to a remarkable effect of the crystal texture of specimens on the maximum strain that can be imposed on specimens without *** on the present results,a way to achieve expedient grain refinement through the cryogenic plane-strain compression was suggested.

关键词： titanium cryogenic deformation texture microstructure

Advancement in materials for energy-saving lighting devices

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Frontiers of Chemical Science and Engineering 2012年第1期6卷 13-26页

作者： Tak h.kim Wentai WANG Qin LI Department of Chemical Engineering Curtin UniversityPerth 6845Australia

This review provides a comprehensive account of energy efficient lighting devices, their working principles and the advancement of these materials as an underpinning to the development of technology. Particular attention has been given to solid state lighting devices and their applications since they have attracted the most interest and are the most promising. Solid state lighting devices including white light emitting diodes （LEDs）, organic LEDs （OLEDs）, quantum-dot LEDs （QLEDs） and carbon-dot LEDs （CLEDs） are promising energy efficient lighting sources for displays and general lighting. however there is no universal solution that will give better performance and efficiency for all types of applications. LEDs are replacing traditional lamp,; for both general lighting and display applications, whereas OLEDs are finding their own special application,; in various areas. QLEDs and CLEDs have advantages such.as high quantum yields, narrow emission spectra, tunable emission spectra and good stability over OLEDs, so applications for these devices are being extended to new types of lighting sources. There is a great dean of research on these materials and their processing technologies and the commercial viability of these technologies appears strong.

关键词： energy-saving lighting devices solid statelighting devices

Microstructures of Ti-48%Ni shape memory melt-spun ribbons

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中国有色金属学会会刊：英文版 2006年第B01期16卷 92-95页

作者：邢鸿雁 h.Y.kim S.MIYAZAKI College of Mechanical Engineering Tianjin University of Science and TechnologyTianjin 300222China Institute of Materials Science University of TsukubaTsukuba 305-8573Japan

The effect of wheel speed on microstructures of Ti-48%Ni (mole fraction) melt-spun ribbons was investigated by X-ray diffractometry, scanning electron microscopy and transmission electron microscopy. When the wheel speed is 26 and 42 m/s, the as-spun ribbons are completely crystallized to the Ti-Ni B2 phase. The Ti-rich plate precipitates lying on {100} planes are observed in the as-spun ribbon fabricated with.a wheel speed of 26 m/s. The spherical Ti2Ni precipitates are observed at grain boundaries in the as-spun ribbons fabricated with.a wheel speed of 42 m/s. Amorphous and B2 phases coexist in the as-spun ribbon fabricated with.a wheel speed of 52 m/s. The uniformity of grain size in h.at treated ribbons decreases with increasing wheel speed.

关键词：形状记忆合金钛-镍薄膜显微结构快淬

Enhanced thermoelectric performance of spark plasma sintered p-type Ca_(3-x)Y_(x)Co_(4)O_(9+δ)systems

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Journal of Materials Science & Technology 2020年第20期52卷 212-222页

作者： J.S.Cha D.h.kim h.Y.hong K.Park Faculty of Nanotechnology and Advanced Materials Engineering Sejong UniversitySeoul05006Republic of Korea

highly textured dense Ca3-xYxCo4 O9+δ(0≤x≤0.3)samples were fabricated by combining sol-gel process with spark plasma sintering(SPS).Y^3+substitution for Ca^2+simultaneously increased the Seebeck coefficient and reduced the thermal *** latter was attributed to the increase in lattice anharmonicity,structural distortion,and grain boundary area,which enhanced the phonon ***2.7Y0.3Co4 O9+δshowed the largest dimensionless figure-of-merit(ZT=0.194)at 1073 K because it had the largest Seebeck coefficient and the lowest thermal *** ZT value was 55%larger than that of undoped Ca3 Co4 O9(0.125 at 1073 K).Therefore,Y^3+substitution,sol-gel powder synthesis,and SPS are highly effective for enhancing the thermoelectric prope rties of Ca_(3)Co_(4)O_(9).

关键词： Electrical conductivity Ca_(3)Co_(4)O_(9) Thermoelectric properties Seebeck coefficient Thermal conductivity Spark plasma sintering

Model-based adaptive locomotion and clustering control of microparticles through ultrasonic topological charge modulation

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Applied Mathematics and Mechanics(English Edition) 2023年第4期44卷 623-640页

作者： h.S.LEE h.X.CAO D.JUNG C.S.kim School of Mechanical Engineering Chonnam National UniversityGwangju 61186South Korea Korea Institute of Medical Microrobotics Gwangju 61011South Korea

We present a novel motion control technique for microrobot clusters to exploit the characteristics of the ultrasonic *** method comprises two steps,i.e.,introducing an ultrasonic actuation(UA)linear model for three-dimensional(3D)locomotion and controlling the topological charge(TC)in the ultrasonic vortex for microrobot ***,the TC is a controllable parameter for the expansion and contraction of the pressure null space inside the *** present a TC control method to cluster sporadically distributed microrobots in a specific *** validate the concept,a UA system composed of 30 ultrasonic transducers with 1 Mhz frequency is fabricated,and the characteristics of the generated acoustic pressure field are analyzed through ***,the performances of the adaptive controller for precise 3D locomotion and the TC control method for clustering are ***,the UA technology,which performs both clustering and locomotion in a complex manner,is validated with.a gelatin phantom in an in-vitro environment.

关键词： ultrasonic actuation(UA) topological charge(TC) adaptive control particle manipulation

Effect of Alloying Elements on Microstructure,Martensitic Transformation and Mechanical Properties of Ni-Mn Based Alloys

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Journal of Materials Science & Technology 2009年第5期25卷 649-654页

作者： K.Alvarez h.Y.kim S.Miyazaki Graduate School University of TsukubaIbaraki 305-8573Japan Institute of Materials Science University of TsukubaTsukubaIbaraki 305-8573Japan

The microstructural features, shape memory behavior and mechanical properties of Ni-Mn based alloys were investigated by differential scanning calorimetry （DSC）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and thermal cycling test under various stresses. The transformation temperatures shifted toward lower temperatures when adding a third element into the Ni-Mn system. The addition of 10 at. pct Fe increased considerably the mechanical properties exhibiting still high transformation temperatures. however, it was found that in NiMn40Fe10 alloy the martensitic transformation is not thermoelastic in nature. The mechanism of this transformation and the crystallography of Ni-Mn（50-x）-Fex （x=5, 7, 10, 20 at. pct） alloys are presented.

关键词： Ni-Mn based alloys Martensitic transformation temperature L10 phase

Computational Analysis of the Compressible Flow Driven by a Piston in a Ballistic Range

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Journal of Thermal Science 2007年第4期16卷 360-369页

作者： G.Rajesh R.Mish.a h.G.Kang h.D.kim School of Mechanical Engineering Andong National University388Songcheon-DongAndong-760 749Korea

The ballistic range has long been employed in a variety of engineering fields such.as high-velocity impact engineering, projectile aerodynamics and aeroballistics, since it can create an extremely high-pressure state in very short time. Since the operation of the ballistic range includes many complicated phenomena, each process should be understood in detail for the performance enhancement of the device. One of the main processes which have significant influence on the device performance is the compression process of the driver gas. Most of the studies available in this field hardly discuss this phenomenon in detail and thus lack a proper understanding of its effect on the whole system performance. In the present study, a computational analysis has been made to investigate the fluid dynamic aspects of the compression process in the pump tube of a ballistic range and to assess how it affects the performance of the ballistic range. The results obtained are validated with the available experimental data. In order to evaluate the system performance, several performance parameters are defined. Effect of a shock tube added in between the pump tube and launch tube on the performance of the ballistic range is also studied analytically. Performance of the ballistic range could be significantly improved by the proper selection of the pump tube and high-pressure tube parameters and the addition of the shock tube.

关键词： Ballistic range compressible flow piston shock tube chimera mesh