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Enhanced solid-electrolyte interface efficiency for practically viable hydrogen-air fuel cell systems

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Journal of Energy Chemistry 2025年第1期100卷 356-368页

作者： Venkitesan Sakthivel Dong Jin yoo Graduate School Department of Energy Storage/Conversion Engineering (BK21 FOUR) Hydrogen and Fuel Cell Research Center Jeonbuk National University Jeonju Department of Life Science Jeonbuk National University

Proton exchange membrane fuel cells （PEMFCs） provide an appealing sustainable energy system,with the solid-electrolyte membrane playing a crucial role in its overall ***,sulfonated poly（1,4-phenylene ether-ether sulfone）(SPEES),an aromatic hydrocarbon polymer,has garnered considerable attention as an alternative to Nafion ***,the long-term durability and stability of SPEES present a significant *** this context,we introduce a potential solution in the form of an additive,specifically a core–shell-based amine-functionalized iron titanate （A–Fe2TiO5）,which holds promise for improving the lifetime,proton conductivity,and power density of SPEES in *** modified SPEES/A–Fe2TiO5composite membranes exhibited notable characteristics,including high water uptake,enhanced thermomechanical stability,and oxidative ***,the SPEES membrane loaded with 1.2 wt%of A–Fe2TiO5demonstrates a maximum proton conductivity of 155 mS cm-1,a twofold increase compared to the SPEES membrane,at 80°C under 100%relative humidity （RH）.Furthermore,the 1.2 wt%of A–Fe2TiO5/SPEES composite membranes exhibited a maximum power density of 397.37 mW cm-2and a current density of 1148 mA cm-2at 60°C under 100%RH,with an opencircuit voltage decay of 0.05 m V/h during 103 h of continuous *** study offers significant insights into the development and understanding of innovative SPEES nanocomposite membranes for PEMFC applications.

关键词： Composite membranes

Ground settlement during tunneling in groundwater drawdown environment-Influencing factors

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Underground Space 2016年第1期1卷 20-29页

作者： Chungsik yoo School of Civil Architectural Engineering and Landscape ArchitectureSungkyunkwan University2066 Seoboo RoJan-An GuSuwonKyong-Gi Do 16419Republic of Korea

In this paper,the results of a parametric study on groundwater drawdown-induced surface settlement during tunneling in waterbearing ground are presented.A calibrated stress–pore pressure coupled finite element model was adopted for the parametric *** results were analyzed to establish the relationships between key design issues,such as the ground surface settlement and groundwater drawdown,and influencing *** artificial neural network(ANN)-based sensitivity analysis was performed to obtain insight into the relative importance of the influencing *** results indicated that the primary influencing factors on the settlement development are the thickness and stiffness of the soil layer within the drawdown zone and the lining permeability,while the initial void ratio and the permeability of the soil layer were considered secondary influencing *** implications and findings of the study are discussed.

关键词： Conventional tunneling Ground settlement Groundwater Finite element method Stress-pore pressure coupled analysis

Representation of Urban Buildings Using Modified Relief Mapping

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Journal of Computer Science & Technology 2006年第2期21卷 204-208页

作者： Byounghynn yoo Soonhung Han Department of Mechanical Enginccring Koren Aduanced Institute of Science and TechnologyDeajeon305-701Korea

This paper describes the real-time mapping displacement of buildings onto the polygon model of base terrain of geo-spatial information,The buildings are represented as height maps,lcading to low memory requirements and not involving changes of the original geometry（*** vertices are created or displaced）.The displacement of buildings is mapped toward the protruding direction,The base of textrue which represents the ground in topography is correctly mapped onto base polygon without any *** approach can exhibit the correct,occlusions between buildings and ground due to parallax and correct self-occlusion.

关键词： acrial photograph digital map displacement mapping gco-visualization image-based rendering

Numerical Modeling of a Spar Platform Tethered by a Mooring Cable

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Chinese Journal of Mechanical Engineering 2015年第4期28卷 785-792页

作者： ZHU Xiangqian yoo Wan-Suk Computer Aided Engineering Laboratory School of Mechanical Engineering Pusan National University

Virtual simulation is an economical and efficient method in mechanical system design. Numerical modeling of a spar platform, tethered by a mooring cable with a spherical joint is developed for the dynamic simulation of the floating structure in ocean. The geometry modeling of the spar is created using finite element methods. The submerged part of the spar bears the buoyancy, hydrodynamic drag force, and effect of the added mass and Froude-Krylov force. Strip theory is used to sum up the forces acting on the elements. The geometry modeling of the cable is established based on the lumped-mass-and-spring modeling through which the cable is divided into 10 elements. A new element-fixed local frame is used, which is created by the element orientation vector and relative velocity of the fluid, to express the loads acting on the cable. The bottom of the cable is fixed on the seabed by spring forces, while the top of the cable is connected to the bottom of the spar platform by a modified spherical joint. This system suffers the propagating wave and current in the X-direction and the linear wave theory is applied for setting of the propagating wave. Based on the numerical modeling, the displacement-load relationships are analyzed, and the simulation results of the numerical modeling are compared with those by the commercial simulation code, Proteus DS. The comparison indicates that the numerical modeling of the spar platform tethered by a mooring cable is well developed, which provides an instruction for the optimization of a floating structure tethered by a mooring cable system.

关键词： numerical modeling dynamic simulation spar platform mooring cable spherical joint

Numerical Modeling of a Spherical Buoy Moored by a Cable in Three Dimensions

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Chinese Journal of Mechanical Engineering 2016年第3期29卷 588-597页

作者： ZHU Xiangqian yoo Wan-Suk Computer Aided Engineering Laboratory School of Mechanical Engineering Pusan National University

Floating facilities have been studied based on the static analysis of mooring cables over the past decades. To analyze the floating system of a spherical buoy moored by a cable with a higher accuracy than before, the dynamics of the cables are considered in the construction of the numerical modeling. The cable modeling is established based on a new element frame through which the hydrodynamic loads are expressed efficiently. The accuracy of the cable modeling is verified with an experiment that is conducted by a catenary chain moving in a water tank. In addition, the modeling of a spherical buoy is established with respect to a spherical coordinate in three dimensions, which can suffers the gravity, the variable buoyancy and Froude-Krylov loads. Finally, the numerical modeling for the system of a spherical buoy moored by a cable is established, and a virtual simulation is proceeded with the X- and Y-directional linear waves and the X-directional current. The comparison with the commercial simulation code Proteus DS indicates that the system is accurately analyzed by the numerical modeling. The tensions within the cable, the motions of the system, and the relationship between the motions and waves are illustrated according to the defined sea state. The dynamics of the cables should be considered in analyzing the floating system of a spherical buoy moored by a cable.

关键词： numerical modeling dynamic simulation spherical buoy mooring cable dynamics of cable

Dynamic Inertia Response Support by Energy Storage System with Renewable Energy Integration Substation

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Journal of Modern Power Systems and Clean Energy 2020年第2期8卷 260-266页

作者： Yeuntae yoo Seungmin Jung Gilsoo Jang Korea University SeoulKorea Hanbat National University DaejeonKorea

In recent years,the expansion of renewable energy in electric power systems has been increasing at such a rapid pace that it has started affecting frequency *** generators connected to the grid produce variable amounts of power,and in most cases have no inherent inertia response(IR)to the system ***,the high penetration of renewable generators in the system results in low inertia and frequency *** renewable generators account for a high proportion of the supply in a power system,the use of energy storage systems(ESSs)with frequency-support algorithms(in the place of synchronous generators)can stabilize the *** participation of ESSs in frequency support must be organized precisely,so that they are fully devoted to their own *** this paper,the frequency-support parameters of ESSs are calculated for achieving stable frequency response from a *** estimation and calibration process is conducted during the active power-order change of the ESSs in the substation,and is verified through electromagnetic-transients-including-DC(EMTDC)-based simulations.

关键词： Energy storage system(ESS) frequency response inertia renewable energy substation

EP-Bot: Empathetic Chatbot Using Auto-Growing Knowledge Graph

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Computers, Materials & Continua 2021年第6期67卷 2807-2817页

作者： SoYeop yoo OkRan Jeong Gachon University Seongnam-si13120Korea

People occasionally interact with each other through *** particular,we communicate through dialogue and exchange emotions and information from *** are essential characteristics of natural *** artificial intelligence is an integral part of all the technologies that allow computers to communicate like *** a computer to interact like a human being,it must understand the emotions inherent in the conversation and generate the appropriate ***,existing dialogue systems focus only on improving the quality of understanding natural language or generating natural language,excluding *** propose a chatbot based on emotion,which is an essential element in ***-Bot(an Empathetic PolarisX-based chatbot)is an empathetic chatbot that can better understand a person’s utterance by utilizing PolarisX,an autogrowing knowledge *** extracts new relationship information and expands the knowledge graph *** is helpful for computers to understand a person’s common *** proposed EP-Bot extracts knowledge graph embedding using PolarisX and detects emotion and dialog act from the *** it generates the next utterance using the ***-Bot could understand and create a conversation,including the person’s common sense,emotion,and *** verify the novelty and accuracy of EP-Bot through the experiments.

关键词： Emotional chatbot conversational AI knowledge graph emotion 1 Introduction

Failure mechanism and control technology of deep soft-rock roadways:Numerical simulation and field study

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Underground Space 2023年第5期12卷 1-17页

作者： Ningkang Meng Jianbiao Bai Chungsik yoo School of Mines China University of Mining and TechnologyXuzhou 221116China State Key Laboratory of Coal Resources and Safe Mining China University of Mining and TechnologyXuzhouJiangsu 221116China School of Civil Architectural Engineering&Landscape ArchitectureSungkyunkwan UniversitySuwon 16419South Korea

Large deformations such as roof subsidence,floor heave,and two-sided deformations occur frequently in deep soft-rock *** deformation becomes more severe under the combined effect of high in-situ and mining-induced stresses,which detrimentally affect the safe mining of *** on the geological conditions and roadway failure characteristics of the Nanyaotou coal mine in Shanxi province,China,we used comprehensive numerical simulations and field observations to study roadway deformation and *** deformation mechanism of deep soft-rock roadways under dynamic pressures is described,and the corresponding control measures are *** deformation and fracture development characteristics of roadways surrounding rocks were explored with a primary support scheme,and its effects were *** radius of the plastic zone and the displacement deformation of the roadway were studied by using theoretical analysis,and a combined-support design of‘‘anchor bolt+anchor cable+shotcrete+deep and shallow borehole grouting+inverted arch”was proposed to limit deformations and relieve the stress in the surrounding *** simulations and field monitoring showed that the combined support scheme can effectively mitigate the large deformations of ventilation roadways and provide guidance for the stable control of deep soft-rock roadways.

关键词： Deep soft-rock roadways Large deformation Failure mechanism Universal distinct element code(UDEC) Combined support

High performance of TiO_(2)/Cu_(x)O photoelectrodes for regenerative solar energy storage in a vanadium photoelectrochemical cell

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Green Energy & Environment 2022年第4期7卷 704-711页

作者： Harin yoo Doohwan Lee Jung Hyeun Kim Department of Chemical Engineering University of Seoul163 SiripdaeroDongdaemun-guSeoul02504South Korea

Photocatalysts for harvesting solar energy to either electricity or chemical fuels have attracted much attention recently, but they have big obstacles such as wide bandgaps and rapid charge recombinations to overcome for final applications. In this study, we investigates a useful method to utilize vanadium redox pairs, which are commonly applied for vanadium redox flow batteries, to diminish charge recombinations and thus to enhance photocurrent response in regenerative solar energy storage. The results reveal significant improvements in photocurrent density by forming cuprous and cupric oxides in TiO_(2)/Cu_(x)O electrodes under solar AM 1.5 illuminations using the vanadium photoelectrochemical storage cell at 0.025 mol L^(-1) of vanadium redox species in the acid electrolytes. In addition, the stabilized photocurrent density of the copper content optimized TiO_(2)/Cu_(x)O electrodes is almost tripled from the TiO_(2) only electrode because the charge recombinations can be mitigated with the content optimized TiO_(2)/Cu_(x)O electrodes. Therefore, the optimized TiO_(2)/Cu_(x)O electrode results in the highest charge storing performance in the catholyte chamber, and the roles of vanadium redox species are also clearly demonstrated.

关键词： Photocatalyst Photoelectrochemical Copper oxide Charge recombination Redox pairs