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Journal of Materials Science & Technology 2017年第9期33卷 919-925页

作者： T.Y.Kwak W.J.Kim rare Metal r&bd group Korea Institute of Industrial Technology Department of Materials Science and Engineering Hongik University

An ultrafine-grained（UFG） Mg-13Zn-1.55 Y alloy（ZW132） with a high volume fraction（7.4%） of icosahedral phase（I-phase, Mg;Zn;Y） particles was prepared by applying high-ratio differential speed rolling（HrDSr） on the cast microstructure following homogenization. The alloy exhibited excellent superplasticity at low temperatures(tensile elongations of 455% and 1021% 473 K-10;s;and 523 K-10;s;,respectively). Compared with UFG Mg-9.25Zn-1.66 Y alloy（ZW92） with a lower volume fraction of I-phase particles（4.1%）, which was prepared using the same processing routes, the UFG ZW132 alloy exhibited a higher thermal stability of grain size. rapid grain coarsening, however, occurred at temperatures beyond523 K, leading to a loss of superplasticity. The high-temperature deformation behavior of the HrDSrprocessed ZW132 alloy could be well described assuming that the mechanisms of grain boundary sliding and dislocation climb creep competed with each other and considering that the grain-size was largely increased by accelerated grain growth at the temperatures beyond 523 K.

关键词： Magnesium alloy Superplastic deformation Ultrafine grain Icosahedral quasicrystal Grain growth

Optimal intensity and duration of cupping for minimizing possible mechanical skin deformation

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Journal of Traditional Chinese Medicine 2021年第5期41卷 817-825页

作者： Bummo Ahn Soobyeong Kim robotics r&bd group Korea Institute of Industrial TechnologyAnsan 15588Republic of Korea Department of robotics and Virtual Engineering University of Science and TechnologyAnsan 15588Republic of Korea Wellness Technology r&D Center Natural Arin Medi CorporationSejongsi 30127Republic of Korea

OBJECTIVE:To identify the optimal intensity and duration of cupping that would minimize mechanical skin ***:We developed an optical measurement probe and system for measuring skin color values in real *** applied cupping at the following five Bladder Meridian *** investigate optimal intensity,negative pressure intensity was increased every 2 min up to 80 k *** investigate optimal time,10 measurement sites were selected and negative pressure intensities of 30,60,and 80 k Pa were applied for 5 min *** color information was analyzed by the following skin color values:red color saturation,erythema index,and melanin ***:The red color saturation and erythema index increased steadily up to 60 kpa negative pressure intensity,then decreased between 60 and 80 k ***,maximal values were observed at 60 k *** melanin index consistently increased with increasing negative pressure *** red color saturation and erythema index did not change after 20 s at 60 k Pa negative pressure *** negative pressure intensities below 80 k Pa,significant changes in melanin index were not observed after 20 *** 80 k Pa negative pressure intensity,the melanin index exhibited an increasing pattern for200 s,then showed no ***:To minimize skin deformation,60 k Pa and 20 s were the appropriate intensity and duration when using red color saturation and erythema index as diagnostic *** of the increasing pattern up to 80 k Pa negative pressure intensity,the optimal intensity of melanin index could not be *** applying 80 k Pa negative pressure intensity and using melanin index as the diagnostic index,we recommend a duration of 200 s.

关键词： ecchymosis petechiae pigmentation erythema melanins

Uncertainty analysis of flow rate measurement for multiphase flow using CFD

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Acta Mechanica Sinica 2015年第5期31卷 698-707页

作者： Joon-Hyung Kim Uk-Hee Jung Sung Kim Joon-Yong Yoon Young-Seok Choi Department of Mechanical Design Engineering Hanyang University Thermal & Fluid System r&bd group Korea Institute of Industrial Technology Energy System Engineering University of Science and Technology

The venturi meter has an advantage in its use,because it can measure flow without being much affected by the type of the measured fluid or flow ***,it has excellent versatility and is being widely applied in many *** flow of a liquid containing air is a representative example of a multiphase flow and exhibits complex flow *** particular,the greater the gas volume fraction（GVF）,the more inhomogeneous the flow *** a result,using a venturi meter to measure the rate of a flow that has a high GVF generates an *** this study,the cause of the error occurred in measuring the flow rate for the multiphase flow when using the venturi meter for analysis by *** ensure the reliability of this study,the accuracy of the multiphase flow models for numerical analysis was verified through comparison between the calculated results of numerical analysis and the experimental *** a result,the Grace model,which is a multiphase flow model established by an experiment with water and air,was confirmed to have the highest ***,the characteristics of the internal flow Held about the multiphase flow analysis result generated by applying the Grace model were analyzed to find the cause of the uncertainty occurring when measuring the flow rate of the multiphase flow using the venturi meter.A phase separation phenomenon occurred due to a density difference of water and air inside the venturi,and flow inhomogeneity happened according to the flow velocity difference of each *** was confirmed that this flow inhomogeneity increased as the GVF increased due to the uncertainty of the flow measurement.

关键词： Multiphase flow Measurement Numerical analysis Venturi meter Gas volume fraction(GVF) Uncertainty Multiphase flow model Grace model

Microstructure and Mechanical Properties of TiB-Containing Al–Zn Binary Alloys

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Journal of Materials Science & Technology 2016年第7期32卷 653-659页

作者： Sang-Soo Shin Gil-Yong Yeom Tae-Yang Kwak Ik-Min Park Department of Materials Science and Engineering Pusan National University Busan 609-735 Republic of Korea Liquid Processing & Casting Technology r&bd group Korea Institute of Industrial Technology Incheon 21999 Republic of Korea

The microstructure and mechanical properties of newly developed Al-35Zn cast alloys with TiB refiner addition were evaluated by X-ray diffractometry, optical microscopy, and scanning electron microscopy coupled with energy dispersive spectrometry. The microstructure of these alloys featured α-Al den- drites surrounded by AI-Zn （α ＋ rI） eutectic structures. After the addition of TiB refiner, the alloy grain sizes decreased, and its morphology abruptly changed from dendritic to equiaxed grains. Such an im- proved microstructure of the modified alloys was accompanied by a significant increase in the tensile strength and elongation percentage compared to those of the AI-Zn or Zn-Al-based alloys. The results showed that with the increase of TiB content up to 0.05%, the morphology of α-Al dendrites and α ＋ T1 phases changed from coarse dendrite and lamellar structures into independent and fine ones. Based on these results, the effect of TiB refiner addition on the microstructure and mechanical properties of the AI-35Zn binary alloys was investigated.

关键词： Al-Zn(-Cu) alloyEutectic structureHigh strengthTiB2

Biotechnological valorization of algal biomass:an overview

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Systems Microbiology and Biomanufacturing 2021年第2期1卷 131-141页

作者： A.Naresh Kumar Jeong-Jun Yoon Gopalakrishnan Kumar Sang-Hyoun Kim School of Civil and Environmental Engineering Yonsei UniversitySeoul 03722Republic of Korea Intelligent Sustainable Materials r&bd group Korea Institute of Industrial Technology(KITECH)CheonanChungnam 31056Republic of Korea

Algal biomass has significant advantages over terrestrial plants in terms of CO2 sequestration,biomass productivity,waste-water treatment along with multiple biobased products *** versatility and high carbohydrate content of microalgal biomass act as a potential alternative feedstock to fossil resources and contribute towards the biobased economy *** biomass utilization would play a key role to establish sustainable bioprocess development and technology translation to the industrial *** this framework,the present review discusses the renewable resource potential of algal biomass and its complete utilization for multiple biobased products synthesis in a closed-loop biorefinery *** methods are discussed to obtain high biomass growth and pretreatments to obtain the maximum sugars ***,combined bioprocesses were discussed for the production of biohydrogen,biomethane,bioethanol,short-chain fatty acids(SCFA),medium-chain fatty acids(MCFA),and biopolymers in a closed-loop approach.

关键词： Algal biomass Biorefinery Bioeconomy Closed loop Biohydrogen

Effects of Li addition on microstructure and mechanical properties of Mg-6Al-2Sn-0.4Mn alloys

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Transactions of Nonferrous Metals Society of China 2016年第3期26卷 697-703页

作者： Yong-Ho KIM Hyeon-Taek SON Automotive Component & Materials r&bd group Korea Institute of Industrial TechnologyGwangju 61012Korea Department of rare Metals Engineering University of Science & TechnologyDaejeon 34113Korea

Effects of Li addition (2%, 5%, 8% and 11%) on microstructure and mechanical properties of the as-cast and as-extruded Mg?6Al?2Sn?0.4Mn-based alloys were investigated. Mg?xLi?6Al?2Sn?0.4Mn (x= 2, 5, 8 and 11, mass fraction, %) alloys were cast under an SF6 and CO2 atmosphere at 700 °C. After homogenization heat treatment at 350 °C, cast billets were extruded with a reduction ratio of 40:1 at 200 °C. Li addition to Mg?6Al?2Sn?0.4Mn resulted in the formation of MgSnLi2 and MgAlLi2 and/or AlLi intermetallic compounds and random basal texture. With increasing Li addition,β-Li phase was increased and the average area fraction of precipitates increased. Compression yield strength was increased from 212 to 235, 242 and 239 MPa as Li content was increased from 2% to 5%, 8% and 11%, respectively. Elongation was remarkably increased above 60% in 11% Li alloy. It is probable that Li-containing phases play a significant role in the enhanced mechanical properties by Li addition.

关键词： magnesium alloy Li addition extrusion microstructure mechanical property

Trend of Nitriding on Chromium-Molybdenum Steel via Low Temperature Screen Plasma Technology

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Advances in Materials Physics and Chemistry 2014年第8期4卷 141-152页

作者： Kuk-Hyun Yeo Sang-Gweon Kim Jae-Hoon Lee Jung-Hyun Kong Masahiro Okumiya Heat Treatment Technology r&bd group Korea Institute of Industrial Technology Incheon Korea Toyota Technological Institute Nagoya Japan

Low temperature screen plasma technology, a high plasma density, through using a low energy supply, shows excellent effects on a low alloy chromium-molybdenum steel for plastic molds because it does not show a compound layer and a high surface hardness without a deterioration in matrix hardness. For interest about hardening depth, both the screen plasma nitriding and plasma nitro-carburizing processes were tested including nitrogen, hydrogen and a methane mixed gas environmental at 653 K, 713 K. The optical emission spectroscopy (OES) has been analyzed during screen plasma nitriding (SPN) and a nitro-carburizing process (SPNC) was proceeded at 713 K and the same pressure. I find it difficult to dissociate nitrogen molecules perfectly with neutral nitrogen atoms via the DC-plasma nitriding process. Therefore, the SPN and SPNC process have shown a high density of plasma species even though low temperature plasma conditions have a high peak intensity of Hβ and Hγ in the results of the analysis by OES. The hardness value was measured with the micro-Vickers hardness tester after the SPN, SPNC process and the chemical composition of nitriding layers were traced by GDOES. The screen nitriding layer via the screen plasma technology has shown excellent properties with a thickness depth of about 850 ~ 900 HV without the deterioration of matrix hardness value.

关键词： Screen Plasma Technology Plasma Nitro-Carburizing Optical Emission Spectroscopy Without Compound Layer Chromium-Molybdenum Steel

Effect of Formation of Concentrated Stainless Steel Layer by Thermochemical reaction and Addition of Hydrocarbon Gas on Sintered Part

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Advances in Materials Physics and Chemistry 2018年第5期8卷 227-245页

作者： Sang-Gweon Kim Kuk-Hyun Yeo Jae-Hoon Lee Yong-Ki Cho Masahiro Okumiya Heat Treatment Technology r&bd group Korea Institute of Industrial Technology Siheung Korea Toyota Technological Institute Nagoya Japan

As the environmental load has recently increased, the use of sintered stainless steel for automobile parts is increasing to help weight reducing, high performance and external exposure. Although the low priced pre-mixed sintered stainless steel powder parts are used instead of the high priced pre-alloyed powder parts, there have been problems of poor corrosion resistance and high price because the parts are sintered at low temperature due to the change of final part size. This paper describes the alloying process of producing parts having high hardness and corrosion resistance through expanded high concentration chromium on the surface only of sintered steel, which is relatively easier to sinter, using the pack-chromizing technology to improve hardness and corrosion resistance to solve the problem. Notable is the coating where the activated-chromium formed during the pack-chromizing process remains in the coating layer can lower the friction coefficient of the coated layer to up to 0.1. On the one hand, when the hydrocarbon gas was injected so as to promote the chromium-iron mixed carbide formed, the friction coefficient is increased to 0.4 with high hardness values. The thickness of the chromium alloying layer on the specimen can vary at the same temperature and same phase of the coating layer depending on which chromium resource materials (i.e. chromium or chromium-iron mixed powder) is used.

关键词： Pack-Chromizing Technology Sintered Stainless Steel Sintered Steel Tribological Test Binding Chloride

Design and Experiment of a Bionic Gannet for Plunge-Diving

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Journal of Bionic Engineering 2013年第3期10卷 282-291页

作者： Jianhong Liang Xingbang Yang Tianmiao Wang Guocai Yao Wendi Zhao Institute of robotics Beihang University Beijing 100191 P. R. China

A bionic gannet was developed based on the analysis of the body configuration and skeleton structure and the motion pattern of wings of a gannet in plunge-diving. In the current prototype, adjustable sweptback wings were implemented so as to achieve different body shapes for entering water. The impact acceleration in the longitudinal body axis direction and the axial overload on the body were investigated through the falling-down experiments under different conditions including dropping height, water-entry inclination angle, and wing sweptback angle. It is found that when the above three key parameters are 10 m for dropping height, 0° for wing sweptback angle, and 90° for water-entry inclination angle, the maximum peak impact acceleration and overload are -167.20 m.s-2 and 18.06 respectively. Furthermore, the variation of peak impact acceleration with the three key parameters were also analyzed and discussed.

关键词： bionic gannet plunge-diving peak impact acceleration inclination angle sweepback dropping height

Prototype Design and Experimental Study on Locust Air-Posture righting

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Journal of Bionic Engineering 2014年第3期11卷 459-468页

作者： Diansheng Chen Junmao Yin Kewei Chen Kai Zhao Benguang Zhang robotics Institute Beihang University Beijing 100191 P. R. China

Locust has the capacity to maintain a righting posture and glide through attitude adjustment after leaping. A prototype inspired by the dynamic mechanism of attitude adjustment of locusts was developed. The prototype consists of a pair of wings driven by a four-bar mechanism, and a 2 Degree of Freedom （DOF） tail to imitate the movement of the locust abdomen. The power source, microcontroller, wireless data transmission module, and attitude sensors are contained in the fuselage. Experiments imitating the flight of locust were conducted to determine the mechanism of locust Subsequent Attitude Adjustment （SAA）. The tethered prototype was driven by the movement of the tail and the flapping of the wings. results show that the pitch and yaw of the tail, and the asymmetric action of the flapping wings significantly influence the posture of the prototype. These findings suggest that both the wiggling abdomen and flapping wings contribute to the locust SAA in the air. This research lays the groundwork and technical support for the probable design and development of practical jumping robots with attitude adjustment function.

关键词： attitude adjustment locust air-posture righting prototype design wiggling tail flapping wing