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Oxygen vacancy engineering for tuning the catalytic activity of LaCoO_(3) perovskite

Journal of Rare Earths 2024年第3期42卷 506-514,I0003页

作者： Jeong Hyun Cho Minjae Kim Inchan Yang Kyung Tae Park Chang Houn Rhee Hai Woong Park Ji chul jung Department of Chemical Engineering Myongji UniversityYongin 17058Republic of Korea Institute of Advanced Composite Materials Korea Institute of Science and TechnologyWanju-gunJeollabuk-do 55324Republic of Korea Iron&Steel Process Engineering Research Group POSCOPohang 37859Republic of Korea Hydrogen Research Center Research Institute of Industrial Science&Technology(RIST)Pohang 37673Republic of Korea

Herein, we attempted to engineer oxygen vacancies on the surface of LaCoO_(3) perovskite through simple post-treatments(acid or reductive thermal treatments). Acid treatment induces oxygen vacancies through the selective etching of the La cations, whereas thermal treatment in a reducing atmosphere generates oxygen vacancies by directly removing lattice oxygen. The characterization results confirm that the number of surface oxygen vacancies, which are crucial in various catalytic oxidation reactions,considerably increases in the LaCoO_(3) catalysts treated with acid or reducing gas. Acid treatment enriches the oxygen vacancies while maintaining the structure of the LaCoO_(3) catalysts, which can not be achieved through reductive thermal treatment. Therefore, the acid treatment is considered a promising technique for oxygen vacancy engineering of perovskite catalysts for tuning their catalytic activities. Furthermore,the catalytic activities of the posttreated LaCoO_(3) catalysts for CO oxidation were evaluated and are noted to be considerably better than those of the pristine LaCoO_(3) catalyst due to their abundant oxygen vacancies. Consequently, we conclude that the oxygen vacancies of perovskite catalysts can be effectively engineered via two simple methods and play a significant role in CO oxidation.

关键词： LaCoO_(3)perovskite Acid treatment Reductive thermal treatment Oxygen vacancy CO oxidation Rare earths

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Antiphospholipid syndrome with renal and splenic infarction after blunt trauma:A case report

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World Journal of Clinical Cases 2022年第26期10卷 9404-9410页

作者： Na-A Lee Eui-Sung Jeong Hyun-Seok Jang Yun-chul Park Ji-Hyoun Kang jung-chul Kim Young-Goun Jo Division of Trauma Department of SurgeryChonnam National University Medical School and HospitalGwangju 61469South Korea Division of Rheumatology Department of Internal MedicineChonnam National University Medical School and HospitalGwangju 61469South Korea

BACKGROUND In trauma patients,bleeding is an immediate major *** the same time,there are few cases of acute vascular occlusion after blunt trauma,and it is unclear what assessment and diagnosis should be considered for these ***,we describe a patient diagnosed with antiphospholipid syndrome after a hypercoagulable workup for acute renal and splenic vascular occlusion due to blunt *** SUMMARY A 20-year-old man was admitted to the emergency department with abdominal pain after hitting a tree while riding a sled 10 h *** had no medical *** investigations revealed occlusion of the left renal artery with global infarction of the left kidney and occlusion of branches of the splenic artery with infarction of the central portion of the *** revascularization of the left renal artery occlusion through percutaneous transluminal angioplasty failed due to difficulty in passing the wire through the total *** the presence of acute multivascular occlusions in a young man with low cardiovascular risk,additional laboratory tests were performed to evaluate *** results suggested a high possibility of antiphospholipid *** with a subcutaneous injection of enoxaparin was started and changed to oral warfarin after two *** diagnosis was confirmed,and he continued to visit the rheumatology outpatient clinic while taking *** A hypercoagulable workup can be considered in trauma patients with acute multivascular occlusion,especially in young patients with low cardiovascular risk.

关键词： Wounds and injuries Wounds Nonpenetrating Antiphospholipid syndrome Renal artery obstruction Splenic infarction Case reports

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Oxidative coupling of methane over LaAlO3 perovskite catalysts prepared by a co-precipitation method: Effect of co-precipitation pH value

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Journal of Energy Chemistry 2019年第8期28卷 1-8,I0001页

作者： Yujin Sim Jihoon Yoo Jeong-Myeong Ha Ji chul jung Department of Chemical Engineering Myongji UniversityYongin 17058 Republic of Korea Clean Energy Research Center Korea Institute of Science and TechnologySeoul 02792 Republic of Korea

Oxidative coupling of methane(OCM) was conducted over LaAlO3X catalysts that were prepared by a coprecipitation method using different co-precipitation pH values(X = 6–10). The aim is to investigate the effect of p H values on the catalytic activity of La AlO3 catalysts in this reaction. The results showed that the co-precipitation pH value affected greatly on the formation of chemical species of precipitate precursors in the co-precipitation step, leading to different phases of the finally obtained LaAlO3 *** the co-precipitation pH value increased up to 8, the lanthanum-related phases such as La2 O3 and La(OH)3 were gradually formed as by-products, preventing the formation of LaAlO3 perovskite crystalline structure and facilitating the formation of oxygen vacancies on catalyst surface. However, at pH value of9 or higher, the lanthanum content in the precipitate precursor was increased greatly. Not LaAlO3 perovskite but lanthanum-related phases were developed as main phases, reducing their catalytic activities in this reaction. Among LaAlO3 catalysts, the one prepared at pH = 8 showed the highest C2 yield due to its well-developed oxygen vacancies and electrophilic lattice oxygen. Therefore, the co-precipitation pH value strongly affected the LaAlO3 catalyst activity in OCM reaction. A precious pH control should be required to prepare various perovskite catalysts for the OCM.

关键词： LaAlO3 Perovskite Oxidative coupling of methane Co-precipitation pH value

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Influence of the preparation method on the catalytic activity of Mg-Al hydrotalcites as solid base catalysts

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Green Energy & Environment 2019年第3期4卷 287-292页

作者： Sungjae Park Dahye Kwon Ji Yeon Kang Ji chul jung Department of Chemical Engineering Myongji University

Mg-Al hydrotalcites were synthesized using different preparation methods(a co-precipitation method, a urea method, and a simple one) to analyze their effect on the catalytic activity of these solid base catalysts. The method strongly affected the structure of their layers(e.g., the growth and stacking of the layers, and the type of intercalated anions) and, accordingly, their catalytic activity. The Mg-Al hydrotalcite prepared by co-precipitation showed the best catalytic performance in the isomerization of glucose into fructose, due to the small crystallite size and sand rose morphology enhancing the exposure of surface active sites to reactants.

关键词： Mg-Al hydrotalcite Preparation method Base catalyst Glucose isomerization Fructose

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Development of practical postprocessor for 5-axis machine tool with non-orthogonal rotary axes

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Journal of Central South University 2011年第1期18卷 159-164页

作者： jung Hyoun-chul HWANG Jong-Dae PARK Ki-Beom jung Yoon-Gyo School of Mechatronics Changwon National University

In order to develop a practical postprocessor for 5-axis machine tool,the general equations of numerically controlled(NC) data for 5-axis configurations with non-orthogonal rotary axes were exactly expressed by the inverse kinematics,and a windows-based postprocessor written with Visual Basic was developed according to the proposed *** developed postprocessor is a general system suitable for all kinds of 5-axis machines with orthogonal and non-orthogonal rotary *** implementation of the developed postprocessor and verification by a cutting simulation and machining experiment,the effectiveness of the proposed algorithm is *** is improved by allowing exchange of data formats such as rotational total center position(RTCP) controlled NC data,vector post NC data,and program object file(POF) cutter location(CL) data,and convenience is increased by adding the function of work-piece origin ***,a practical post-processor for 5-axis machining is developed.

关键词：旋转轴非正交后处理机床数据交换格式 RTCP协议 5轴加工配置数据

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Continuity control method of cutter posture vector for efficient five-axis machining

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Journal of Central South University 2011年第6期18卷 1969-1975页

作者： HWANG Jong-dae KIM Sang-myung jung Hyun-chul jung Yoon-gyo School of Mechatronics Changwon National University

During five-axis machining of impeller, the excessive local interference avoidance leads to inconsistency of cutter posture, low quality of machined surface and increase of processing time. Therefore, in order to improve the efficiency of five-axis machining of impellers, it is necessary to minimize the cutter posture changes and create a continuous tool path while avoiding interference. By using an MC-space algorithm for interference avoidance, an MB-spline algorithm for continuous control was intended to create a five-axis machining tool path with excellent surface quality and economic feasibility. A five-axis cutting experiment was performed to verify the effectiveness of the continuity control. The result shows that the surface shape with continuous method is greatly improved, and the surface roughness is generally favorable. Consequently, the effectiveness of the suggested method is verified by identifying the improvement of efficiency of five-axis machining of an impeller in aspects of surface quality and machining time.

关键词：五轴加工矢量控制加工刀具连续性有效性验证姿势刀具姿态刀具路径

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Tuning the base properties of Mg–Al hydrotalcite catalysts using their memory effect

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Journal of Energy Chemistry 2020年第7期29卷 229-236,I0008页

作者： Dahye Kwon Ji Yeon Kang Suna An Inchan Yang Ji chul jung Department of Chemical Engineering Myongji UniversityYongin 17058Republic of Korea

Herein,the relationship between the structure and base properties of Mg–Al hydrotalcite catalysts was comprehensively investigated in relation to heat treatment and rehydration processes,which are well known as memory effects of *** structure of Mg–Al hydrotalcites changed from layered double hydroxide(LDH)to mixed metal oxide and subsequently to a spinel structure during heat treatment,and it was returned from mixed metal oxide to a LDH structure by *** on various characterizations,we successfully proposed a detailed mechanism of memory *** also confirmed that the Mg–Al hydrotalcites had weak or strong base sites and that their base properties could be systematically tuned by heat treatment and *** prepared Mg–Al hydrotalcites were applied to a model reaction,isomerization of glucose to fructose,as base *** the catalysts tested,the rehydrated Mg–Al hydrotalcite efficiently produced fructose due to its appropriate base and structure *** finally concluded that the base sites of Mg–Al hydrotalcites can be designed as desired by heat treatment and ***,through systematic design of the base sites of Mg–Al hydrotalcites,these can be promising catalysts for various heterogeneous reactions over base catalysts,giving excellent catalytic performances.

关键词： Mg–Al hydrotalcite Structure Base properties Heat treatment Rehydration

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Efficient page layout analysis on small devices

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第6期10卷 800-804页

作者： Eun-jung HAN Chee-onn WONG Kee-chul jung Kyung-ho LEE Eun-yi KIM Department of Naval Architecture and Ocean Engineering Inha University Human-Centered Interfaces Lab Department of Digital MediaSoongsil University Internet and Media Engineering Konkuk University

Previously we have designed and implemented new image browsing facilities to support effective offline image contents on mobile devices with limited capabilities: low bandwidth, small display, and slow processing. In this letter, we fulfill the automatic production of cartoon contents fitting small-screen display, and introduce a clustering method useful for various types of cartoon images as a prerequisite stage for preserving semantic meaning. The usage of neural networks is to properly cut the various forms of pages. Texture information that is useful for grayscale image segmentation gives us a good clue for page layout analysis using the multilayer perceptron (MLP) based x-y recursive algorithm. We also automatically frame the segment MLP using ag-glomerative segmentation. Our experimental results show that the combined approaches yield good results of segmentation for several cartoons.

关键词：页面布局屏幕显示器装置信件科学聚类分析方法图像分割自动化生产

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Development of tool-path generation module for 5-axis control machining of impellers

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Journal of Central South University 2012年第12期19卷 3424-3429页

作者： jung Hyoun-chul SON Hwang-jin jung Yoon-gyo School of Mechatronics Changwon National UniversityChangwon 641-773Korea

An impeller is difficult to machine because of severe collision due to the complex shape,overlapping and twisted shape of the impeller ***,most computer aided manufacturing(CAM)software companies have developed CAM module for manufacturing impeller according to their CAM *** these dedicated modules are difficult to use for inexperienced *** purpose of this work is to develop a tool-path generation module for *** this purpose,it is based on Visual Basic language and used CATIA graphical *** result of simulation for generated tool-path by the module is *** it has slow processing speed compared to other commercial modules,but it is easy to use.

关键词：生成模块刀具路径叶轮加工 CAM软件 Basic语言控制形状复杂

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Bifunctionality of Cu/ZnO catalysts for alcohol-assisted low-temperature methanol synthesis from syngas:Effect of copper content

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Journal of Energy Chemistry 2017年第3期26卷 373-379页

作者： Ilho Kim Gihoon Lee Heondo Jeong Jong Ho Park Ji chul jung Department of Chemical Engineering Myongji University Korea Institute of Energy Research

Alcohol-assisted low-temperature methanol synthesis was conducted over Cu/ZnO;catalysts while varying the copper content（X）. Unlike conventional methanol synthesis, ethanol acted as both solvent and reaction intermediate in this reaction, creating a different reaction pathway. The formation of crystalline phases and characteristic morphology of the co-precipitated precursors during the co-precipitation step were important factors in obtaining an efficient Cu/ZnO catalyst with a high dispersion of metallic copper,which is one of the main active sites for methanol synthesis. The acidic properties of the Cu/ZnO catalyst were also revealed as important factors, since alcohol esterification is considered the rate-limiting step in alcohol-assisted low-temperature methanol synthesis. As a consequence, bifunctionality of the Cu/ZnO catalyst such as metallic copper and acidic properties was required for this reaction. In this respect, the copper content（X） strongly affected the catalytic activity of the Cu/ZnO;catalysts, and accordingly, the Cu/ZnO;.5 catalyst with a high copper dispersion and sufficient acid sites exhibited the best catalytic performance in this reaction.

关键词： Low-temperature methanol synthesis Alcohol-assisted Bifunctionality Cu/ZnO catalysts Copper content

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