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A mass and energy estimation for the hydrogen utilization in the iron-making process

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Science China(Technological Sciences) 2011年第7期54卷 1655-1660页

作者： Wan ho KIM Dong joon MIN Department of Materials Science and Engineering YONSEI University

The possibility of using hydrogen to lower CO 2 emissions in the iron-making process was confirmed by the heat and mass balances in the blast furnace operation. The mass and heat balances for hydrogen utilization in the blast furnace were estimated by using the basic concept of RIST operating diagram. In this study, the RIST operating diagram was modified to be suitable for representing the operation with respect to hydrogen, where the RIST operating diagram is a graphical representation of heat and mass balance in blast furnace operation. RIST operating diagram was applied here to some individual parameters of interest such as H 2 injection in blast furnace process to reduce coke (carbon consumption). It was observed that the point W moved to the right in the RIST operating diagram under the condition of increasing hydrogen injection at tuyere, which originates from the contribution of gas composition (O/H 2 ) equilibrated with Fe/FeO at a certain temperature. Point P also moved downward due to heat requirement with respect to hydrogen utilization, by which the new RIST operating diagram for hydrogen utilization was able to be constructed. Under the condition of hydrogen injection, the expected overall carbon consumption in the blast furnace decreased due to the contribution of hydrogen.

关键词： hydrogen carbon consumption (CO2 emission) mass and heat balances RIST operating diagram blast furnace

Compensating the impurities on the Cu surface by MOFs for enhanced hydrocarbon production in the electrochemical reduction of carbon dioxide

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Journal of Energy Chemistry 2022年第3期31卷 68-73,I0003页

作者： Shin joon Kang Jong ho Won Hansaem choi Woohyeong Sim Mun Kyoung Kim Siraj Sultan Youngkook Kwon Hyung Mo Jeong School of Mechanical Engineering and Department of Smart Fab.Technology Sungkyunkwan University2066 Seobu-roJangan-guSuwon 16419Republic of Korea Department of Chemistry Kookmin University77 Jeongneung-roSeongbuk-guSeoul 02707Republic of Korea School of Energy and Chemical Engineering Emergent Hydrogen Technology R&D CenterUlsan National Institute of Science and Technology50 UNIST-gilUlsan 44919Republic of Korea

Copper(Cu)provides a cost-effective means of producing value-added fuels through the electrochemical reduction of carbon dioxide(CO_(2)RR).however,we observed the production of hydrocarbons via CO_(2)RR on commercial Cu films is less efficient because of the surface impurities,i.e.,*** monoxide(CO),a reaction intermediate of CO_(2)RR to hydrocarbons,binds strongly to the Fe sites and interrupts the production of hydrocarbons,resulting in an active hydrogen evolution reaction(HER).Herein,we report a method of blocking the effect of Fe impurities on the Cu surface through the preferential growth of nano-sized metal-organic frameworks(MOFs)on Fe *** zirconium(Zr)-based MOFs(UiO-66)forms a compensating layer on Cu film via the terephthalic acid(TPA)-Fe coordination bond,the Ui O-66 coated Cu film(UiO-66@Cu)presents significantly improved hydrocarbon Faradaic efficiency(FE)of 37.59%compared to 14.68%FE on commercial Cu film(99.9%purity)by suppressing *** to X-ray photoelectron spectroscopy(XPS)analysis,the UiO-66 ligand binds to entire metallic Fe site on the Cu surface,while metallic Cu is ***,UiO-66@Cu provides active sites of Cu for CO_(2)RR and leads to highly efficient and selective production of hydrocarbons.

关键词： Impurity on Cu film Zr-based MOFs Electrocatalysts CO_(2)reduction Hydrocarbon

Study of Partial Coefficients for Design of Semicircular Breakwaters

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China Ocean Engineering 2010年第1期24卷 29-40页

作者：郄禄文 Byung ho choi College of Civil Engineering Hebei University Department of Civil and Environmental Engineering Sungkyunkwan University300 Chunchun-dongJangan-GuSuwon

In the present study, the reliability design of semicircular breakwater is based on the verification of the rules defined by standard specifications, where partial coefficients are introduced to ensure safety. The reliability of the semicircular breakwaters has been analyzed by using the Hasofer-Lind method to determine the reliability index of structure that has correlated loads, utilizing the long-term observed wave data at a given place. The relation curve between reliability index and safety factor in the traditional design method, as well as the relationships between reliability index and partial coefficients, have been obtained. This paper proposes values of partial coefficients for the design expression of semicircular breakwaters in the cases of anti-sliding and anti-overturning.

关键词： partial coefftcient reliability index correlated variables semicircular breakwater

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

Generation of tumor spheroids using a droplet-based microfluidic device for photothermal therapy

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Microsystems & Nanoengineering 2020年第1期6卷 796-805页

作者： Jong Min Lee Ji Wook choi Christian D.Ahrberg Hyung Woo choi Jang ho Ha Seok Gyu Mun Sung joon Mo Bong Geun Chung Department of Mechanical Engineering Sogang UniversitySeoulKorea Division of Chemical Industry Yeungnam University CollegeDaeguRepublic of Korea Research Center Sogang UniversitySeoulKorea Department of Biomedical Engineering Sogang UniversitySeoulKorea

Despite their simplicity,monolayer cell cultures are not able to accurately predict drug behavior in vivo due to their inability to accurately mimic cell-cell and cell-matrix *** contrast,cell spheroids are able to reproduce these interactions and thus would be a viable tool for testing drug ***,the generation of homogenous and reproducible cell spheroids on a large scale is a labor intensive and slow process compared to monolayer cell ***,we present a droplet-based microfluidic device for the automated,large-scale generation of homogenous cell spheroids in a uniform *** the microfluidic system,the size of the spheroids can be tuned to between 100 and 130μm with generation frequencies of 70 *** demonstrated the photothermal therapy(PTT)application of brain tumor spheroids generated by the microfluidic device using a reduced graphene oxide-branched polyethyleneimine-polyethylene glycol(rGO-BPEI-PEG)nanocomposite as the PTT ***,we generated uniformly sized neural stem cell(NSC)-derived neurospheres in the droplet-based microfluidic *** also confirmed that the neurites were regulated by ***,this droplet-based microfluidic device could be a powerful tool for photothermal therapy and drug screening applications.

关键词： fluid viable simplicity

Adhesion and Suction Functions of the Tip Region of a Nectar-drinking Butterfly Proboscis

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Journal of Bionic Engineering 2017年第4期14卷 600-606页

作者： Seung Chul Lee Jun ho Kim Sang joon Lee Department of Mechanical Engineering Pohang University of Science and Technology Pohang 37673 Gyeongbuk Republic of Korea Center for Biofluid and Biomimic Research Pohang University of Science and Technology Pohang 37673 Gyeongbuk Republic of Korea

In this study, we investigated the dynamic functions of the tip region of the butterfly proboscis through which liquid is sucked during liquid feeding. The microstructures and flow patterns in the tip region of the proboscis were in vivo analyzed. The tip region can be divided into two functional sections： namely adhesion and suction sections. The liquid adheres to the adhesion section during liquid suction. Although the tip region has numerous slits connected to food canal of the proboscis, liquid is mainly sucked through the suction section, which section is submerged in the fluid pulled by the adhesion section and then successfully imbibes liquid. To check the dynamic functions of the tip region, we fabricated a suction tip model having adhesion and suction parts. The in vitro model experiments show that the hydrophilicity of the adhesion part and the existence of the suction inlet improve the liquid uptake driven by a suction pump. This study may provide insights for the biomimetic design of nectar-feeding butterflies.

关键词： butterfly proboscis nectar-feeding strategy suction

Shear deformable finite beam elements for composite box beams

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Acta Mechanica Sinica 2014年第2期30卷 223-240页

作者： Nam-Il Kim Dong-ho choi Department of Architectural Engineering Sejong University Department of Civil and Environmental Engineering Hanyang University

The shear deformable thin-walled composite beams with closed cross-sections have been developed for coupled flexural, torsional, and buckling analyses. A theoretical model applicable to the thin-walled laminated composite box beams is presented by taking into account all the structural couplings coming from the material anisotropy and the shear deformation effects. The current composite beam includes the transverse shear and the restrained warping induced shear deformation by using the first-order shear deformation beam theory. Seven governing equations are derived for the coupled axial-flexural-torsional-shearing buckling based on the principle of minimum total potential energy. Based on the present analytical model, three different types of finite composite beam elements, namely, linear, quadratic and cubic elements are developed to analyze the flexural, torsional, and buckling problems. In order to demonstrate the accuracy and superiority of the beam theory and the finite beam elements developed by this study,numerical solutions are presented and compared with the results obtained by other researchers and the detailed threedimensional analysis results using the shell elements of ABAQUS. Especially, the influences of the modulus ratio and the simplified assumptions in stress-strain relations on the deflection, twisting angle, and critical buckling loads of composite box beams are investigated.

关键词： Thin-walled Composite box beam Deflection Twisting angle Buckling load Shear deformation

Development of a Biomimetic Quadruped Robot

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Journal of Bionic Engineering 2007年第4期4卷 193-199页

作者： Thanhtam ho Sunghac choi Sangyoon Lee Department of Mechanical Design and Production Engineering Konkuk University Seoul 143-701 Korea

This paper presents the design and prototype of a small quadruped robot whose walking motion is realized by two piezocomposite actuators. In the design, biomimetic ideas are employed to obtain the agility of motions and sustainability of a heavy load. The design of the robot legs is inspired by the leg configuration of insects, two joints （hip and knee） of the leg enable two basic motions, lifting and stepping. The robot frame is designed to have a slope relative to the horizontal plane, which makes the robot move forward. In addition, the bounding locomotion of quadruped animals is implemented in the robot. Experiments show that the robot can carry an additional load of about 100 g and run with a fairly high velocity. The quadruped prototype can be an important step towards the goal of building an autonomous mobile robot actuated by piezocomposite actuators.

关键词： quadruped robot piezocomposite actuator bounding locomotion

Temperature Distribution and Thermal Stresses in Various Conditions of Moving Heating Source during Line Heating Process

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Journal of Thermal Science 2012年第1期21卷 82-87页

作者： Yoon Hwan choi Yeon Won Lee Kwang choi Deog Hee Doh Kyoung joon Kim Department of Mechanical and Automotive Engineering Pukyong National University Steel Structure Research Division Research Institute of Industrial Science & Technology Division of Mechanical and information Engineering Korea Maritime University

Line heating method is widely used to manufacture curved surfaces in ship building. The main factors governing the quality of the manufactured products are the moving velocity of the heating source, heating strength, and heating ways. In this study, the temperature distributions of the heated plate were investigated with the condition that the line heating process was automatic. The temperature variations were also investigated with the changes of those three variables. The numerical results showed that the peak temperature decreased as the moving velocity of the heating source increased. It also revealed that the peak temperatures changed linearly with the changes of the heating source.

关键词： Moving heat source Line heating Thermal stress Residual deformation Conductive heat transfer