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Microstructures and Mechanical Properties of Rapidly Solidified Mg-Al-Zn-MM Alloys

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Journal of Materials Science & Technology 2008年第1期24卷 89-92页

作者： Yeon-wook kim Department of Advanced Materials Engineering Keimyung University Daegu 704-701Korea

Mg-Al-Zn-M M （misch metal） alloy powders were manufactured by inert gas atomization and the characteristics of alloy powders were *** spite of the low fluidity and easy oxidation of the magnesium melt,the spherical powder was made successfully with the improved three piece nozzle systems of gas atomization unit. It was found that most of the solidified powders with particles size of less than 50μm in diameter were single crystal and the solidification structure of rapidly solidified powders showed a typical dendritic morphology because of supercooling prior to *** spacing of secondary denrite arms was deceasing as the size of powders was *** rapidly solidified powders were consolidated by vacuum hot extrusion and the effects of misch metal addition to AZ91 on mechanical properties of extruded bars were also *** extrusion of the rapidly solidified powders,their dendritic structure was broken into fragments and remained as grains of about 3μm in *** Mg-Al-Ce intermetallic compounds formed in the interdendritic regions of powders were finely broken,*** tensile strength and ductility obtained in as-extruded Mg-9 wt pct Al-1 wt pct Zn-3 wt pct MM alloy wereσ-（T.S.） =383 MPa andε=10.6%,*** of these improvements on mechanical properties were resulted from the refined microstructure and second-phase dispersions.

关键词： Mg alloy Gas atomization Misch metal Hot extrusion

Forecasting promising technology using analysis of patent information:Focused on next generation mobile communications

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Journal of Central South University 2014年第11期21卷 4303-4310页

作者： CHOI Seung-wook YOU Yen-Yoo NA kwan-Sik Department of Knowledge Service & Consulting Hansung UniversitySeoul Korea Department of Management Information Systems Seowon UniversityCheongju Korea

In order to forecast promising technologies in the field of next generation mobile communication, various patent indicators were analyzed such as citation per patent, patent family information, patent share, increase rate, and patent activity. These indicators were quantified into several indexes and then integrated into an evaluation score to provide promising technologies. As a result of the suggested patent analysis, four technologies out of twenty two in details classification were selected, which showed outstanding technology competitiveness, high patent share and increasing rates as well as high recent-patent-ratios and triad-patent-family-ratios. Each of the selected technologies scored more than 10 points in total, and the following four technologies were suggested as promising ones in the field of next generation mobile communication: 1) 3GPP based mobile communication, 2) beyond 4G mobile communication, 3) IEEE 802.16 based mobile communication, which are in medium classification of broadband mobile communication system, and 4) testing/certification system of mobile communication, which is in medium classification of mobile communication testing/certification system.

关键词： next generation mobile communication promising technology forecasting patent information patent analysis patent indicators

Surface treatment to improve corrosion resistance of Al plate heat exchangers

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中国有色金属学会会刊：英文版 2009年第B9期19卷 28-31页

作者： Jong-Soon kim Tae-Ho KANG In-kwan kim Department of Mechanical Engineering Pu kyong National University

The correlations between thermal and physical properties were studied through thermal conductivity measurements, hardness tests, salt spray tests (AASS) among the surface treatment samples named K20, K40 with thickness of 20, 40 μm respectively and raw sample named K00. In thermal conductivity measurements, there are little differences among the samples as K00, K20 and K40, they exhibit 153.39, 150.69 and 149.76 W/(m·K), respectively. According to hardness tests, K00, K20 and K40 exhibit 87.9, 259.7 and 344.8 in Vickers values. In the result of salt spray tests to examine the effects on corrosion resistance, K00, K20 and K40 exhibit the grade of 3?5, 2.0?9.8 and 10, respectively. The mutual relation of the above results was analyzed. It is found that the surface treatments do not affect the thermal conductivity of aluminum and result in the improvement of physical properties. As a result of the technology, the surface improvement of aluminum alloy specimen is achieved without thermal degradation. It validates the ability of the aluminum plate heat exchangers with surface treatment to enhance the corrosion resistance. Present work is performed as the first fundamental threshold in the process of aluminum plate heat exchangers development to check out its possibility, therefore the next step-experimental and numerical study of practical aluminum plate heat exchangers will be made.

关键词：板式换热器表面处理耐铝性物理性能导热系数硬度测试盐雾试验耐腐蚀性

Implementation of configuration dependent stiffness proportional damping for the dynamics of rigid multi-block systems

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Earthquake Engineering and Engineering Vibration 2003年第1期2卷 87-98页

作者： Yun Byeong Chae Jae kwan kim R & D Division Chungsuk Engineering57Garak-dongSongpa-kuSeoul138-802Korea Assistant Engineer School of Civil Urban and Geosystem EngineeringSeoul National UniversitySeoul151-742Korea Associate Professor

The distinct element method(DEM)has been used successfully for the dynamic analysis of rigid block sys- *** of many difficulties associated with DEM is modeling of *** this paper,new procedures are proposed for the damping modeling and its numerical implementation in distinct element analysis of rigid muhi-block *** stiff- ness proportional damping is constructed for the prescribed damping ratio,based on the non-zero fundamental frequency ef- fective during the time interval while the boundary conditions remain essentially *** this time interval,the funda- mental frequency can be estimated without complete eigenvalue *** damping coefficients will vary while the damp- ing ratio remains the same throughout the entire analysis.A new numerical procedure is developed to prevent unnecessary energy loss that can occur during the separation *** procedures were implemented in the development of the dis- tinet element method for the dynamic analyses of piled multi-block *** analysis results |or the single-block and two-block systems were in a good agreement with the analytic *** to the seismic analyses of piled four- block systems revealed that the new procedures can make a significant difference and may lead to much-improved results.

关键词： multi-block systems stiffness proportional damping rocking impact distinet element method rigid body dynamics

Incorporation of Ionic Conductive Polymers into Sulfide Electrolyte-Based Solid-State Batteries to Enhance Electrochemical Stability and Cycle Life

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Energy & Environmental Materials 2024年第6期7卷 4-12页

作者： Juhyoung kim Woonghee Choi Seong-Ju Hwang Dong wook kim Advanced Materials Division Korea Research Institute of Chemical Technology(KRICT)Daejeon 34114Korea Department of Material Science and Engineering Yonsei UniversitySeoul 03722Korea Department of Material Science and Engineering Seoul National UniversitySeoul 08826Korea Advanced Materials and Chemical Engineering University of Science and Technology(UST)Daejeon 34113Korea

Sulfide-based inorganic solid electrolytes are promising materials for high-performance safe solid-state *** high ion conductivity,mechanical characteristics,and good processability of sulfide-based inorganic solid electrolytes are desirable properties for realizing high-performance safe solid-state batteries by replacing conventional liquid ***,the low chemical and electrochemical stability of sulfide-based inorganic solid electrolytes hinder the commercialization of sulfide-based safe solid-state ***,the instability of sulfide-based inorganic solid electrolytes is intensified in the cathode,comprising various *** this study,carbonate-based ionic conductive polymers are introduced to the cathode to protect cathode materials and suppress the reactivity of sulfide *** instruments,including electrochemical spectroscopy,X-ray photoelectron spectroscopy,and scanning electron microscopy,confirm the chemical and electrochemical stability of the polymer electrolytes in contact with sulfide-based inorganic solid ***-based solid-state cells show stable electrochemical performance over 100 cycles when the ionic conductive polymers were applied to the cathode.

关键词： composite cathode electrochemical stability ionic conductive polymer solid-state battery sulfide solid electrolyte

Strangulated small bowel hernia through the port site:A case report

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World Journal of Gastroenterology 2008年第44期14卷 6881-6883页

作者： Jun Hyun Lee wook kim Department of Surgery Holy Family HospitalCollege of MedicineThe Catholic University of KoreaBucheon 420-717South Korea

Port site hernia develops through a fascial or peritoneal layer that was inadequate or not repaired. It is a rare complication of laparoscopic surgery which may lead to serious problems. Here,we present a 77-year-old female,diagnosed with a small bowel hernia through a 10-mm port site. We had performed ten cases of laparoscopy-assisted distal gastrectomy before this case. The patient complained of left lower abdominal pain with a palpable mass. Abdominal CT showed an incarcerated small bowel hernia and the patient underwent segmental resection of the strangulated small bowel through a minimally extended port site incision.

关键词： Port site hernia Strangulated small bowel Minimally extended port site incision

Simple reactor for the synthesis of silver nanoparticles with the assistance of ethanol by gas-liquid discharge plasma

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Plasma Science and Technology 2019年第4期21卷 34-43页

作者： Pan LU Dong-wook kim Dong-Wha PARK Department of Chemistry and Chemical Engineering Inha University100 Inha-Ro.Michuhol-guIncheon 22212Republic of Korea Regional Innovation Center for Environmental Technology of Thermal Plasma(RIC-ETTP: Inha University100 Inha-RoMichuhol-gu.Incheon 22212.Republic of Korea

Atmospheric pressure plasma technology is gaining increasing importance because it is a simple and tunable synthesis process for the production of metallic *** addition to the development of the power supply,improving the reactor is also one of the main strategies to enhanee the *** this study,a simple reactor for the gas-liquid discharge plasma induced by argon gas was applied to synthesize silver nanopailicles from silver nitrate(AgNO3)in *** AC power supply with a peak voltage of 3.5 kV was *** frequency and on-time were set to 50 kHz and 2.5“s,*** oscilloscope showed that the rising time was approximately 2“*** ethanol was used as the source for the reactive reducing *** more additional comp on ents existed in the solution during the discharge and neither of the electrodes was in contact with the treated *** temperature in creased by 10°C within 1 min without a cooling *** was the main impurity and was expected to be produced from the decomposition of the organics under the *** elevated temperature decreased the organic by-products by evaporation and could also decrease the production of *** electron microscopy showed that the spherical silver nanoparticles with a size of approximately 10 nm were synthesized with a crystal structure and that a low concentration of ethanol prefers the production of the mono-dispersed colloid.

关键词： silver nanoparticles synthesis nonthermal plasma ethanol reduction gas-liquid discharge

Improved corrosion resistance of Mg alloy AZ31B induced by selective evaporation of Mg using large pulsed electron beam irradiation

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Journal of Materials Science & Technology 2019年第5期35卷 891-901页

作者： Woo Jin Lee Jisoo kim Hyung wook Park Department of Mechanical Aerospace and Nuclear Engineering Ulsan National Institute of Science and Technology

Large pulsed electron beam(LPEB) irradiation was employed as a surface treatment of magnesium(Mg)alloy AZ31B to enhance its corrosion and wear resistance. Selective evaporation of Mg induced by LPEB irradiation at an energy density of 5J/cm^2 for 40 cycles has led to the formation of an Al-enriched resolidified layer with nano-grained structure consisting of Mg3.1 Al0.9 metastable phase. The formation of such a re-solidified layer after LPEB irradiation has enabled a decrease in corrosion rate of Mg alloy AZ31B in 3.5% NaCl solution. Different equivalent electrical circuit models were proposed to account for the corrosion behavior of untreated Mg alloy AZ31B and those subjected to LPEB irradiation. A decrease in wear depth when compared to that of the untreated alloy suggests an increase in wear resistance of LPEB-irradiated Mg alloy AZ31B. Adhesive wear is the predominant mechanism of untreated Mg alloy AZ31B while abrasive wear mechanism dominates for LPEB-irradiated Mg alloy AZ31B.

关键词： Magnesium alloys Electron beam treatment Corrosion resistance Microstructure Rapid re-solidification Wear resistance

Liquid crystal-powered Mie resonators for electrically tunable photorealistic color gradients and dark blacks

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Light(Science & Applications) 2022年第6期11卷 1098-1108页

作者： Trevon Badloe Joohoon kim Inki kim Won-Sik kim wook Sung kim Young-Ki kim Junsuk Rho Department of Mechanical Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea Department of Biophysics Institute of Quantum BiophysicsSungkyunkwan UniversitySuwon 16419Republic of Korea Department of Intelligent Precision Healthcare Convergence Sungkyunkwan UniversitySuwon 16419Republic of Korea Department of Chemical Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea Department of Electrical Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea POSCO-POSTECH-RIST Convergence Research Center for Flat Optics and Metaphotonics Pohang 37673Republic of Korea National Institute of Nanomaterials Technology(NINT) Pohang 37673Republic of Korea

Taking inspiration from beautiful colors in nature,structural colors produced from nanostructured metasurfaces have shown great promise as a platform for bright,highly saturated,and high-resolution *** plasmonic and dielectric materials have been employed to produce static colors that fulfil the required criteria for high-performance color printing,however,for practical applications in dynamic situations,a form of tunability is *** of the additive color palette of red,green,and blue enable the expression of further colors beyond the three primary colors,while the simultaneous intensity modulation allows access to the full color ***,we demonstrate an electrically tunable metasurface that can represent saturated red,green,and blue pixels that can be dynamically and continuously controlled between on and off states using liquid *** use this to experimentally realize ultrahigh-resolution color printing,active multicolor cryptographic applications,and tunable pixels toward high-performance full-color reflective displays.

关键词： saturated printing colors