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Numerical characteristics of the full operator hybrid simulation method

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Earthquake Engineering and Engineering Vibration 2011年第3期10卷 453-463页

作者： chung-Chan Hung Yong-song Chen Department of Civil Engineering Central University （NCU） Chinese Taipei Department of Mechanical Engineering Chung Cheng University （NCCU） Chinese Taipei

The full operator method （FOM） has been proposed to overcome some of the shortcomings of the commonly used operator splitting method （OSM）. In particular, the FOM is improved by increasing the accuracy of both the predictor and corrector using the estimated tangent stiffness of the tested structure. The numerical characteristics of the FOM, including stability and accuracy, are investigated in this study. It is shown that FOM is conditionally stable. The stability and accuracy characteristics are dependent on the accuracy of the estimated tangent stiffness and the parameters associated with the acceleration variation in the time-stepping integration method. Mass-spring systems with different types of nonlinearity, including hardening, stiffening, and softening behavior, are used to evaluate the performance of the FOM. It is found that the FOM can capture these types of nonlinearity with satisfactory accuracy. Using a prototype 12-story composite coupled wall system, the influences of the strong nonlinearity of the system as well as the displacement control errors from hydraulic actuators on the performance of the FOM are explored. The results show that the FOM is capable of generating reasonably accurate results despite the presence of strong structural nonlinearity and displacement control errors.

关键词： hybrid simulation tangent stiffness numerical characteristic composite coupled wall system collapse behavior nonlinear behavior

Anticipating the lifespan: Predicting the durability of an anode-supported solid oxide fuel cell short stack over 50,000 h

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Progress in Natural Science:Materials International 2024年第3期34卷 606-613页

作者： Muhammad Zubair Khan Amjad Hussain Seung-Bok Lee Tak-Hyoung Lim rak-Hyun song Department of Materials Science & Engineering Pak-Austria Fachhochschule: Institute of Applied Sciences and Technology Hydrogen Energy Research Division Korea Institute of Energy Research Department of Advanced Energy and System Engineering Korea University of Science and Technology (UST)

In the present study, the operational lifetime of a solid oxide fuel(SOFC) short stack is predicted by investigating the performance degradation of both the short stack and its cells throughout 1000 h at 800°C. The short stack and integral cell voltages are continuously measured during the long-term test, with electrochemical impedance spectroscopy(EIS) conducted every 200 h. The short stack voltage decreased rapidly for the initial 200–300 h and afterwards, it decreased at a slow rate due to the increase in the Ohmic and polarization resistances in the same manner. Scanning electron microscopy results show that there is no delamination or cracking among constituent layers of the short-stack cells. The single degradation effects of the Ni coarsening in the anode, cation migration and surface segregation in cathode and oxide scale growth in metallic interconnect mesh are successfully integrated into a comprehensive lifetime prediction model. The experimentally measured voltage degradation data of the short stack fits well with the developed mathematical model and allows the successful prediction of the lifetime up to 50,000 h.

关键词： SOFC Stack Degradation Impedance Lifetime

Impacts of methanol fuel on vehicular emissions:A review

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Frontiers of Environmental Science & Engineering 2022年第9期16卷 115-134页

作者： chung song Ho Jianfei Peng UnHyok Yun Qijun Zhang Hongjun Mao Tianjin Key Laboratory of Urban Transport Emission Research College of Environmental Science and EngineeringNankai UniversityTianjin 300071China High-Technology Development Institution Kim II Sung UniversityPyongyang 999093Democratic People’s Republic of Korea Laboratory of Ship Research Department of Ship&Marine EngineeringKim Chaek University of TechnologyPyongyang 999093Democratic People’s Republic of Korea

The transport sector is a significant energy consumer and a major contributor to urban air *** present,the substitution of cleaner fuel is one feasible way to deal with the growing energy demand and environmental *** has been recognized as a good alternative to gasoline due to its good combustion *** the past decades,many studies have investigated exhaust emissions using methanol-gasoline ***,the conclusions derived from different studies vary significantly,and the explanations for the effects of methanol blending on exhaust emissions are also *** review summarizes the characteristics of CO,HC,NO_(x),CO_(2),and particulate emissions from methanol-gasoline blended fuels and pure methanol ***,HC,CO_(2),particle mass(PM),and particle number(PN)emissions decrease when methanol-blended fuel is used in place of gasoline ***_(x) emission either decreases or increases depending on the test conditions,i.e.,methanol ***,this review synthesizes the mechanisms by which methanol-blended fuel influences pollutant *** review provides insight into the pollutant emissions from methanol-blended fuel,which will aid policymakers in making energy strategy decisions that take urban air pollution,climate change,and energy security into account.

关键词： Methanol fuel Vehicular emission Emission reduction Cleaner fuel Gasoline substitute

Triangulated Cylinder Origami-Based Piezoelectric/Triboelectric Hybrid Generator to Harvest Coupled Axial and Rotational Motion

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Research 2021年第1期2021卷 460-468页

作者： Jihoon chung Myunghwan song Seh-Hoon chung Woojin Choi Sanghyun Lee Zong-Hong Lin Jinkee Hong Sangmin Lee School of Mechanical Engineering Chung-Ang University84Heukseok-roDongjak-guSeoulRepublic of Korea Department of Chemical&Biomolecular Engineering College of EngineeringYonsei University50 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea Institute of Biomedical Engineering and Department of Power Mechanical Engineering National Tsing Hua University101Section 2Kuang-Fu RoadHsinchu 30013Taiwan

Piezoelectric nanogenerators(PENGs)and triboelectric nanogenerators(TENGs)are representative technologies that can harvest mechanical *** general,piezoelectric/triboelectric hybrid generators can harvest considerable energy with a limited input;however,PENGs and TENGs entail different requirements for harvesting ***,PENGs produce a large output when a large mechanical strain is applied,and TENGs require a large surface area to produce a high ***,it is necessary to develop an innovative strategy in terms of the structural design to satisfy the requirements of both PENGs and *** this study,we developed a triangulated cylinder origami-based piezoelectric/triboelectric hybrid generator(TCOHG)with an origami structure to enable effective energy *** proposed structure consists of a vertical contactseparation TENG on the surface of the triangulated cylinder,PENG on the inner hinge,and rotational TENG on the top substrate to harvest mechanical energy from each *** generator could produce a separate electrical output with a single *** TCO-HG could charge a 22μF commercial capacitor and power 60 LEDs when operated.

关键词： harvesting cylinder generator

A dynamic infiltration technique to synthesize nanolayered cathodes for high performance and robust solid oxide fuel cells

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Journal of Energy Chemistry 2022年第7期31卷 201-210,I0006页

作者： Saeed Ur Rehman Ho-Seon song Hye-Sung Kim Muhammad Haseeb Hassan Dong-Woo Joh rak-Hyun song Tak-Hyoung Lim Jong-Eun Hong Seok-Joo Park Seung-Bok Lee High Temperature Energy Conversion Laboratory Korea Institute of Energy Research152Gajeong-roYuseong-gu.Daejeon34129.Republic of Korea Department of Advanced Energy and System Engineering University of Science and Technology.217 Gajeong-ro.Yuseong-gu.Daejeon 34113.Republicof Korea

Solution infiltration is a popular technique for the surface modification of solid oxide fuel cell(SOFC)***,the synthesis of nanostructured SOFC cathodes by infiltration is a tedious process that often requires several infiltration and high temperature(≥500℃)calcination ***,fabricating large-area nanostructured cathodes via infiltration still requires serious ***,we propose a facile and scalable urea assisted ultrasonic spray infiltration technique for nanofabrication of SOFC *** is demonstrated that by using urea as a precipitating agent,the calcination after each infiltration cycle can be omitted and the next infiltration can be performed just after a drying step(≤100℃).Finally,the precipitates can be converted into a desired catalyst phase in single calcination thus,a nanostructured cathode can be fabricated in a much faster *** is also shown that the low calcination temperature of the cathode(≤900℃)can produce highly durable SOFC performance even without employing a Ce_(0.9)Gd_(0.1)O_(2)(GDC)diffusion barrier layer which provides the ease of SOFC *** coupling with an ultrasonic spray technique,the urea assisted infiltration can be scaled up for any desired cathode ***_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3) nanolayered cathode was fabricated and it was characterized by scanning electron microscope(SEM),X-ray diffraction(XRD),and transmission electron microscopy(TEM)*** showed the formation of a nanolayer cathode just after 5 cycles of the urea assisted infiltration while the XRD and TEM confirmed the phase and stoichiometric uniformity of the 100 nm cathode *** effectiveness of the newly developed technique was further verified by the stable operation of a GDC buffer layer free SOFC having an active cathode area of 25 cm^(2) during a 1200 h durability *** research outcomes propose urea assisted ultrasonic spray infiltration as a facile,scalable,and commercially viable method

关键词： Solid oxide fuel cell(SOFC) Cathode Infiltration Nanolayer Nanofabrication GDC barrier layer free SOFC

Acute limb ischemia after minimally invasive cardiac surgery using the ProGlide:A case series

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World Journal of Clinical Cases 2022年第35期10卷 13052-13057页

作者： Jonggeun Lee Up Huh Seunghwan song chung Won Lee Department of Thoracic and Cardiovascular Surgery Pusan National University School of MedicineBiomedical Research InstitutePusan National University HospitalBusan 49241South Korea

BACKGROUND We report two cases of acute femoral artery occlusion following the use of ProGlide in minimally invasive cardiac surgery and insertion of large-bore catheters through the common femoral *** will add to the existing body of literature by highlighting the possible complications associated with the use of ProGlide and reiterate that the use of the sono-guided ProGlide skill will reduce the incidence of these *** SUMMARY A 78-year-old man underwent minimally invasive cardiac surgery for severe aortic valve *** the operation,the puncture site of the common femoral artery was closed using *** next morning,after regaining consciousness,he complained of pain,motor weakness(grade 2),and coldness in the right lower extremity.A 65-year-old man underwent minimally invasive cardiac surgery for a large secundum atrial septal defect(5 cm×5 cm).After the operation,the puncture site of the common femoral artery was closed using *** extubation,the patient complained of paresthesia of the right *** the patients underwent emergency surgery for acute occlusion of the common femoral *** If the sono-guided ProGlide skill is used,complications can be prevented,and ProGlide can be safely used.

关键词： ProGlide Acute common femoral artery occlusion Minimal invasive cardiac surgery Sono-guided Femoral artery stenosis Case report

Joining Technology of Dissimilar Materials for Automotive Components(Ⅱ)

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Journal of Rare Earths 2004年第z2期22卷 35-37页

作者： Meung Ho Rhee Jong Ho song Woo Young chung Young Myoung Kim Korea Automotive Technology Institute 74 Yongjung-RiPungse-MyunChonanChungnam330-912KOREA Korea Automotive Technology Institute74 Yongjung-RiPungse-MyunChonanChungnam330-912KOREA Korea Automotive Technology Institute74 Yongjung-RiPungse-MyunChonanChungnam330-912KOREA Korea Automotive Technology Institute74 Yongjung-RiPungse-MyunChonanChungnam330-912KOREA

Joining techniques of dissimilar materials for lightweight multi-material automotive body structure were discussed. The joining of 1 .4 mm thickness steel and 2 mm thickness of Al were performed by the new method that is hybrid laser welding system. After aluminum and steel were welded by laser hybrid welding process, the micro-structure investment and the micro-hardness test were carried out. Hybrid laser welding promises a bright future in joining technology of dissimilar materials for automotive components.

关键词： multi-material automotive body dissimilar materials hybrid laser welding

Formation of FeMo_2B_2 phase in boron containing 9Cr-1.5Mo ferritic steels

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Rare Metals 2006年第z2期25卷 213-219页

作者： JUNG Woo-Sang HONG Suk-Woo song Sang-Min SOOK-In Kwun chung Soon-Hyo Materials Science & Technology Division Korea Institute of Science & Technology Seoul 136-791 Korea Department of Materials Science and Engineering Korea University Seoul 136-713 Korea

The segregation and diffusion of boron during heat treatments were studied. The influence of boron contents, aging time and applied stress on FeMo2B2 formation was also studied. Finally, the effects of boron contents and FeMo2B2 formation on the high temperature strength were studied. Boron atoms were segregated to prior austenite grain boundary during normalizing treatment. And these boron atoms were slowly diffused into the grain interior during tempering and aging at 700 ℃. The FeMo2B2 phase was only formed after 1,000 h aging at 700 ℃ in alloy containing 196 ppm boron. The formation of FeMo2B2 phase is accelerated by the applied stress. It was expected that the formation of FeMo2B2 is closely related to the redistribution of boron atoms. The tensile strengths at 700 ℃ are increased with the increase of boron contents. However, the formation of FeMo2B2 phase results in lower tensile strength.

关键词： 9Cr-1.5Mo ferritic steels precipitation behavior boron effect FeMo2B2 phase tensile strength

Silver nanowires with semiconducting ligands for low- temperature transparent conductors

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Nano Research 2016年第2期9卷 392-400页

作者： Brion Bob Ariella Machness Tze-Bin song Huanping Zhou Choong-Heui chung Yang Yang Department of Materials Science and Engineering and California NanoSystems Institute University of California Los Angeles LosAngeles CA 90025 USA Department of Materials Science and Engineering Hanbat National University Daejeon 305-719 Republic of Korea

Metal nanowire networks represent a promising candidate for the rapid fabrication of transparent electrodes with high transmission and low sheet-resistance values at very low deposition temperatures. A commonly encountered challenge in the formation of conductive nanowire electrodes is establishing high-quality electronic contact between nanowires to facilitate long-range current transport through the network. A new system involving nanowire ligand removal and replacement with a semiconducting sol-gel tin oxide matrix has enabled the fabrication of high-performance transparent electrodes at dramatically reduced temperatures with minimal need for post-deposition treatment.

关键词： silver nanowires sol-gel transparent electrodes nanocomposites