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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

Microstructure and corrosion resistance of a Mg2Sn-dispersed Mg alloy subjected to pulsed electron beam treatment

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Journal of Magnesium and Alloys 2020年第2期8卷 345-351页

作者： Daseul Lee Beomcheol Kim Soo-Min Baek Jisoo Kim hyung wook park Jung Gu Lee Sung Soo park School of Materials Science and Engineering Ulsan National Institute of Science and TechnologyUlsan 44919Republic of Korea School of Mechanical Aerospace and Nuclear EngineeringUlsan National Institute of Science and TechnologyUlsan 44919Republic of Korea School of Materials Science and Engineering University of UlsanUlsan 44610Republic of Korea

We report that the corrosion resistance of a Mg-Sn-based alloy with MgzSn precipitates can be considerably improved by surface modification using pulsed electron beam *** alloy subjected to a pulse electron beam treatment showed a modified surface layer with a thickness of〜12 μm,appearing more resistant to corrosion attack than the bare surface of the *** 0.6 M NaCl solution,the alloys with and without the surface modification exhibited average corrosion rates of 4.3 and 8.1 mm y^-1,*** improved corrosion resistance was attributed to reduced cathodic activation,resulting from the surficial reduction of relatively noble Mg2Sn precipitates.

关键词： Magnesium alloy Mg2Sn Intermetallic compound Pulsed electron beam treatment Corrosion

Refractory lipoatrophy treated with autologous whole blood injection:A case report

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World Journal of Clinical Cases 2025年第2期13卷 33-38页

作者： Wonnam Kim Jun Su park En hyung Kim Department of Pharmacology School of Korean MedicinePusan National UniversityYangsan 50612GyeongnamSouth Korea Department of Dermatology College of MedicineChungbuk National UniversityCheongju 28644ChungbukSouth Korea Department of Dermatology Chungbuk National University HospitalCheongju 28644ChungbukSouth Korea

BACKGROUND Intramuscular corticosteroid injection may cause adverse effects such as dermal and/or subcutaneous atrophy,alopecia,hypopigmentation,and *** cutaneous atrophy can spontaneously resolve,several treatment options have been suggested for this *** SUMMARY In this paper,we report a case of corticosteroid injection induced lipoatrophy treated with autologous whole blood(AWB)injection,as the condition had been unresponsive to fractional laser therapy.A 29-year-old female patient visited the dermatology clinic complaining of skin depression on her right buttock area,which had appeared six months *** had been only subtle improvement at the margins after fractional CO_(2) laser treatment;therefore,after obtaining informed consent from the patient,AWB treatment was *** month after the first AWB injection,the size and depth of the lesion had noticeably improved,and a slight improvement was also observed in *** Close observation is the initial treatment of choice for steroid induced skin atrophy;however,for patients in need of immediate cosmetic improvement,AWB injection may be a safe and cost-effective alternative.

关键词： Atrophy Corticosteroid Subcutaneous fat Autologous whole blood injection Laser therapy Case report

Density functional theory study on the role of ternary alloying elements in TiFe-based hydrogen storage alloys

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Journal of Materials Science & Technology 2021年第33期92卷 148-158页

作者： Won-Seok Ko Ki Beom park hyung-Ki park School of Materials Science and Engineering University of UlsanUlsan 44610Republic of Korea Functional Materials and Components R&D Group Korea Institute of Industrial TechnologyGangneung 25440Republic of Korea

The role of additional ternary alloying elements on the performance of stationary TiFe-based hydrogen storage alloys was investigated based on first-principles density functional theory *** a basic step for examinations,the site preference of each alloying element in the stoichiometric and nonstoichiometric B2TiFe compounds was clarified considering possible antisite *** on the revealed site preference,the effect of various possible ternary elements on the hydrogen storage was examined by focusing on the formation enthalpies of TiFeH and TiFeH_(2) hydrides,which were closely related to the change in the location of plateaus in the pressure-composition-temperature *** physical properties such as the volume expansion due to hydride formation were also examined to provide additional criteria for selecting optimum alloying conditions in future alloying design *** alloying elements that maximize the grain boundary embrittlement due to the solute segregation were proposed for the enhanced initial activation of TiFe-based hydrogen storage alloys.

关键词： Hydrogen storage alloy Titanium-iron Density functional theory calculation Metallic hydride

Development of single-action,two-step clinching system using finite element analysis

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中国有色金属学会会刊：英文版 2009年第B09期19卷 266-270页

作者： Seong-wook LEE Tae-hyung KIM Geun-Jo HAN Power & Industrial Systems R&D Center Hyosung Corporation Department of Mechanical Engineering Department of Mechanical Engineering Dong-A University

Traditional manufacturing processes for bending and combining the upper and lower heat insulation plates for a car catalytic converter need two kinds of bending dies. This study was carried out to develop a single-action, two-step clinching system for clinching heat insulation plates. To design the operating mechanism for this clinching system, finite element analysis was used to estimate the bending load needed and to predict the bent shape of the heat insulation plate. Then a recovery and cushioning system was designed for the bending die. It is expected that this new process will improve the manufacturing quality of heat insulation plates and will reduce manufacturing cost. And a higher value-added technique for mold and pressing systems was introduced.

关键词：缓冲系统有限元分析开发汽车催化转化器单动模具技术隔热板板弯曲

Decomposition of CCl_4 and CHCl_3 on gliding arc plasma

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Journal of Environmental Sciences 2006年第1期18卷 83-89页

作者： Antonius Indarto CHOI Jae-wook LEE Hwaung SONG hyung-keun Korea Institute of Science and Technology Clean Technology Research Center P.O. Box 131 Cheongryang Seoul 130-650 Korea Korea Institute of Science and Technology Clean Technology Research Center P.O. Box 131 Cheongryang Seoul 130-650 Korea.

Decomposition of chlorinated hydrocarbons, CCl4 and CHCl3, in gliding plasma was examined. The effects of initial concentrations, total gas flow rates, and power consumption have been investigated. The conversion result was relatively high. It reached 80% for CCl4 and 97% for CHCl3. Using atmospheric air as the carrier gas, the plasma reaction occurred at exothermic reaction and the main products were CO2, CO, and Cl2. Transformation into CCl4 was also detected for CHCl3 decomposition reaction. The conversion of CCh and CHCl3 were increased with the increasing applied frequency and decreasing total gas flow rate.

关键词： plasma gliding arc CCl4 CHCl3 decomposition reaction

A review of C_1 chemistry synthesis using yttrium-stabilized zirconia catalyst

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Journal of Rare Earths 2008年第1期26卷 1-6页

作者： Antonius Indarto Jae-wook Choi Hwaung Lee hyung Keun Song Plasma-Catalyst Chemical Process

C1 chemistry based on synthesis gas, methane, and carbon dioxide offers many routes to industrial chemicals. The reactions related to the synthesis of gas can be classified into direct and indirect approach for making such products, such as acetic acid, dimethyl ether, and alcohol. Catalytic syngas processing is currently done at high temperatures and pressures, conditions that could be unfavorable for the life of the catalyst. Another issue of C1 chemistry is related to the methane-initiated process. It has been known that direct methane conversions are still suffering from low yields and selectivity of products resulting in unprofitable ways to produce products, such as higher hydrocarbons, methanol, and so on. However, many experts and researchers are still trying to find the best method to overcome these barriers, for example, by finding the best catalyst to reduce the high-energy barrier of the reactions and conduct only selective catalyst-surface reactions. The appli- cation of Yttria-Stabilized Zirconia （YSZ） and its combination with other metals for catalyzing purposes are increasing. The existence of an interesting site that acts as oxygen store could be the main reason for it. Moreover, formation of intermediate species on the surface of YSZ also contributes significantly in increasing the production of some specific products. Understanding the phenomena happening inside could be necessary. In this article, the use of YSZ for some C1 chemistry reactions was discussed and reviewed.

关键词： C1 chemistry methane synthesis gas methanol yttria-stabilized zirconia catalyst oxygen storage rare earths

Effectiveness of contrast-enhanced harmonic endoscopic ultrasound for the evaluation of solid pancreatic masses

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World Journal of Gastroenterology 2014年第2期20卷 518-524页

作者： Jin-Seok park hyung Kil Kim Byoung wook Bang Sang Gu Kim Seok Jeong Don Haeng Lee Digestive Disease Center Department of Internal MedicineInha University School of MedicineIncheon 400-711South Korea

AIM:To evaluate the usefulness of contrast-enhanced harmonic endoscopic ultrasound(CH-EUS)in differentiating between pancreatic adenocarcinomas and other pancreatic ***:This retrospective cohort study evaluated90 patients who were seen between November 2010and May *** these patients had solid pancreatic masses that had a hypoechoic appearance on *** patients underwent CH-EUS to evaluate this diagnostic method’s *** mass lesions observed on CH-EUS were classified into three categories based on their echo intensity:hypoenhanced,isoenhanced,and hyperenhanced *** adjusted the sensitivity and the specificity of each category for detecting *** also estimated the accuracy of CH-EUS by comparing it to a pathological ***:Of the 90 patients,62 had a pancreatic ***-seven out of 62 pancreatic adenocarcinomas showed a hypoenhanced pattern on *** sensitivity was 92%,the specificity 68%and the accuracy approximately 82%.The area under the curve of the receiver operating characteristic analysis for CH-EUS was *** is a significant association between the hypoenhanced pattern on CH-EUS and pancreatic duct adenocarcinoma(χ2=35.264,P<0.001).In pathological examinations,the number of specimens for EUS-fine needle aspiration(EUS-FNA)was considered insufficient for diagnosis in three patients,and in two patients,the results were reported to be negative for *** masses in all five patients revealed a hypoenhanced pattern with *** patients were diagnosed with pancreatic adenocarcinoma based on the pathology results of a biopsy,and the remaining two patients were clinically diagnosed with ***:CH-EUS is useful for distinguishing between pancreatic adenocarcinoma and other pancreatic *** a pancreatic mass shows a hypoenhanced pattern on CH-EUS but involves either insufficient samples or negative results with EUS-FNA,clinicians might consider perfo

关键词： Pancreas neoplasm Endoscopic ultrasound SonoVue Contrast media Microbubbles

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

Methane Conversion Using Dielectric Barrier Discharge: Comparison with Thermal Process and Catalyst Effects

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Journal of Natural Gas Chemistry 2006年第2期15卷 87-92页

作者： Antonius Indarto Jae-wook Choi Hwaung Lee hyung Keun Song Korea Institute of Science and Technology Clean Technology Research CenterP.O. Box 131CheongryangSeoul 130-650Korea

The direct conversion of methane using a dielectric barrier discharge has been experimentally studied. Experiments with different values of flow rates and discharge voltages have been performed to investigate the effects on the conversion and reaction products both qualitatively and quantitatively. Experimental results indicate that the maximum conversion of methane has been 80% at an input flow rate of 5 ml/min and a discharge voltage of 4 kV. Experimental results also show that the optimum condition has occurred at a high discharge voltage and higher input flow rate. In terms of product distribution, a higher flow rate or shorter residence time can increase the selectivity for higher hydrocarbons. No hydrocarbon product was detected using the thermal method, except hydrogen and carbon. Increasing selectivity for ethane was found when Pt and Ru catalysts presented in the plasma reaction. Hydrogenation of acetylene in the catalyst surface could have been the reason for this phenomenon as the selectivity for acetylene in the products was decreasing.

关键词： plasma dielectric barrier discharge thermal process methane conversion catalyst