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Steam activation of Fe-N-C catalyst for advanced power performance of alkaline hydrazine fuel cells

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Journal of Energy Chemistry 2022年第1期31卷 276-285,I0008页

作者： sooan bae Jihyeon Park Yuna Hwang Jin-Soo Park Jaeyoung Lee Beomgyun Jeong Research Center for Materials Analysis Korea Basic Science Institute169-14&Gwahak-roDaejeon 34133Republic of Korea School of Earth Sciences and Environmental Engineering Gwangju Institute of Science and Technology123 Cheomdangwagi-ro.Buk-guGwangju 61005Republic of Korea Department of Green Chemical Engineering Sangmyung University31 Sangmyungdae-gilDongnam-gu.CheonanChungnam Province 31066Republic of Korea Ertl Center for Electrochemistry and Catalysis Gwangju Institute of Science and Technology123 Cheomdangwagi-roBuk-giiGwangju 61005Republic of Korea

Alkaline hydrazine liquid fuel cells(AHFC) have been highlighted in terms of high power performance with non-precious metal *** Fe-N-C is a promising non-Pt electrocatalyst for oxygen reduction reaction(ORR),the surface density of the active site is very low and the catalyst layer should be thick to acquire the necessary number of catalytic active *** this thick catalyst layer,it is important to have an optimum pore structure for effective reactant conveyance to active sites and an interface structure for faster charge ***,we prepare a Fe-N-C catalyst with magnetite particles and hierarchical pore structure by steam *** steam activation process significantly improves the power performance of the AHFC as indicated by the lower IR and activation voltage *** on a systematic characterization,we found that hierarchical pore structures improve the catalyst utilization efficiency of the AHFCs,and magnetite nanoparticles act as surface modifiers to reduce the interracial resistance between the electrode and the ion-exchange membrane.

关键词： Alkaline hydrazine fuel cell Oxygen reduction reaction Electrocatalyst Steam activation Ohmic loss Interfacial resistance Surface modifier

Prominent cycling reversibility and kinetics enabled by CaTiO3 protective layer on Zn metal for aqueous Zn-ion batteries

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Journal of Energy Chemistry 2025年第1期100卷 245-258页

作者： Gaeun Lee Yong Nam Ahn Seongjoon So Chanwoo Park Jong-Seong bae Taehyun Park Il Tae Kim Jaehyun Hur School of Chemical Biological and Battery Engineering Gachon University Seongnam Busan Center Korea Basic Science Institute

Aqueous Zn-ion batteries （AZIBs） have received considerable attention owing to their various advantages such as safety,low cost,simple battery assembly conditions,and high ionic ***,they still suffer from serious problems,including uncontrollable dendrite growth,corrosion,hydrogen evolution reaction （HER） from water decomposition,electrode passivation,and unexpected *** creation of a uniform artificial nanocrystal layer on the Zn anode surface is a promising strategy for resolving these ***,we propose the use of a perovskite CaTiO3（CTO） protective layer on Zn（CTO@Zn） as a promising approach for improving the performance of *** CTO artificial layer provides an efficient pathway for Zn ion diffusion towards the Zn metal because of the high dielectric constant （εr=180） and ferroelectric characteristics that enable the alignment of dipole moments and redistribute the Zn2+ions in the CTO *** avoiding the direct contact of the Zn anode with the electrolyte solution,the uneven dendrite growth,corrosion,parasitic side reactions,and HER are mitigated,while CTO retains its mechanical and chemical robustness during ***,CTO@Zn demonstrates an improved lifespan in a symmetric cell configuration compared with bare ***@Zn shows steady overpotential （～68 m V） for 1500 h at 1 mA cm-2/0.5 mA h cm-2,excelling bare ***,when paired with the V2O5-C cathode,the CTO@Zn//V2O5-C full battery delivers 148.4 mA h g-1（based on the mass of the cathode） after 300 *** study provides new insights into Zn metal anodes and the development of high-performance AZIBs.

关键词： Artificial layer Dielectric constant Zn metal anode Zinc aqueous battery

Influence of new town development on the urban heat island-The case of the Bundang area

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Journal of Environmental Sciences 2005年第4期17卷 641-645页

作者： SONG Young-bae School of Architecture Landscape Architecture and Civil Engineering Sung Kyun Kwan UniversityKorea

Five new towns have been developed around the Seoul metropolitan area since 1996 However, these new towns generate lots of traffic and related problems in the areas including those new towns and Seoul as a result of increases in population and a lack of ecological-self-sufficiency. Currently, construction of another new town is under deliberation, and what should be a major consider is the notion that the new town be located within a wide, green zone. Many studies have revealed that green space can play an important role in improving urban eco-meteorological capability and air quality. In order to analyze the urban heat island which will be created by the new urban development, and to investigate the local thermal environment and its negative effects caused by a change of land use type and urbanization, Landsat TM images were used for extraction of urban surface temperature according to changes of land use over the last 15 years. These data are analyzed together with digital land use and topographic information. As a study result, it was found the urban heat island of the study area from 1985 to 1999 rapidly developed which showed a difference of mean temperature above +2 0 Before the Bundang new town construction the temperature of the residential area was the same as a forest, but during the new town construction in 1991 analysis revealed the creation of an urban heat island. The temperature of a forest whose size is over 50% of the investigation area was lowest, and thus the presence of a forest is believed to have a direct cooling effect on the urban environment and its surroundings. The mean temperature of the residential and commercial areas in the study was found to be +4 5 higher than the forest, and therefore this part of land use is believed to be the main factor causing the temperature increase of the urban heat island.

关键词： urban heat island new town development urban climate landsat TM nand 6 air corridor

Toward Fast and Efficient Mobility in Aquatic Environment： A Robot with Compliant Swimming Appendages Inspired by a Water Beetle

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Journal of Bionic Engineering 2017年第2期14卷 260-271页

作者： Bokeon Kwak Joonbum bae Department of Mechanical Engineering UNIST Ulsan Korea

Water beetles are proficient drag-powered swimmers, with oar-like legs. Inspired by this mechanism, here we propose a miniature robot, with mobility provided by a pair of legs with swimming appendages. The robot has optimized linkage structure to maximize the stroke angle, which is actuated by a single DC motor with a series of gears and a spring. A simplified swimming appendage model is proposed to calculate the deflection due to the applied drag force, and is compared with simulated data using COMSOL Multiphysies. Also, the swimming appendages are optimized by considering their locations on the legs using two fitness functions, and six different configurations are selected. We investigate the performance of the robot with various types of appendage using a high-speed camera, and motion capture cameras. The robot with the proposed configuration exhibits fast and efficient movement compared with other robots. In addition, the locomotion of the robot is analyzed by considering its dynamics, and compared with that of a water boatman （Corixidae）.

关键词： mobility compliant appendage drag-powered swimming miniature robot water beetle

Design and Analysis of a Rotational Leg-type Miniature Robot with an Actuated Middle Joint and a Tail （RoMiRAMT-II）

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Journal of Bionic Engineering 2018年第2期15卷 356-367页

作者： Bokeon Kwak Joonbum bae Department of Mechanical Engineering UNIST Ulsan 44919 Korea

In this paper, a rotational leg-type miniature robot with a bioinspired actuated middle joint and a tail is proposed for stable locomotion and improved climbing ability. The robot has four independently actuated rotational legs, giving it advantages of both wheel-type and leg-type locomotion. The design parameters of the rotational legs were determined by 3D simulation within the seven candidates that selected by a newly proposed metric. It also has unique characteristics inspired by biological structures： a middle joint and a tail. An actuated middle joint allows the frontal body to be lifted or lowered, which was inspired by a flexible body joint of animals, to climb higher obstacles. Effectiveness of the middle joint was analytically verified by the geometric analysis of the robot. Additionally, a multi-functional one Degree Of Freedom （1-DOF） tail was added; the tail prevented the body being easily flipped, while allowed the robot to climb higher obstacles. A bristle-inspired micro structure was attached to the tail to enhance straightness of locomotion. Body size of the robot was 158 mm × 80 mm × 85 mm and weighed 581 g including a 7.4 V Li-Polymer battery. The average velocity of the robot was 2.74 m·s ^-1 （17.67 body lengths per second） and the maximum height of an obstacle that the robot could climb was 106 mm （2.5 times of leg length）, which all were verified by experiments.

关键词： locomotion rotational leg actuated middle joint actuated tail bionic miniature robot

On Uniform Decay for Transmission Problem of Kirchhoff Type Viscoelastic Wave Equation

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Acta Mathematica Sinica,English Series 2010年第7期26卷 1197-1206页

作者： Jeong Ja bae Department of Mathematics Dongeui University

In this paper we consider the large time behavior of solutions to an n-dimensional transmission problem for two Kirchhoff type viscoelastic wave equations, that is, the wave propagation over bodies consisting of two physically different types of materials. One component is a simple elastic part while the other is a viscoelastic component endowed with a long range memory. We show that the dissipation produced by the viscoelastic part is strong enough to produce exponential or polynomial decay of the solution

关键词： existence of solution uniform decay wave equation boundary value problem a priori estimates

ON TRANSMISSION PROBLEM FOR KIRCHHOFF TYPE WAVE EQUATION WITH A LOCALIZED NONLINEAR DISSIPATION IN BOUNDED DOMAIN

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Acta Mathematica Scientia 2012年第3期32卷 893-906页

作者： Jeong Ja bae Department of Mathematics Dongeui UniversityPusan 614-714Korea

In this article, we consider the global existence and decay rates of solutions for the transmission problem of Kirchhoff type wave equations consisting of two physi- cally different types of materials, one component is a Kirchhoff type wave equation with nonlinear time dependent localized dissipation which is effective only on a neighborhood of certain part of the boundary, while the other is a Kirchhoff type wave equation with nonlinear memory.

关键词： Existence of solution uniform decay transmission problem Kirchhoff type wave equation boundary value problem localized dissipation

GLOBAL EXISTENCE FOR THE NONHOMOGENEOUS QUASILINEAR WAVE EQUATION WITH A LOCALIZED WEAKLY NONLINEAR DISSIPATION IN EXTERIOR DOMAINS

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Acta Mathematica Scientia 2009年第5期29卷 1203-1215页

作者： Jeong Ja bae Department of Mathematics University of Ulsan

It is proved that the global existence for the nonhomogeneous quasilinear wave equation with a localized weakly nonlinear dissipation in exterior domains.

关键词： quasilinear wave equation localized weakly nonlinear dissipation exterior domains

Simulation of water entry of an elastic wedge using the FDS scheme and HCIB method

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Journal of Hydrodynamics 2013年第3期25卷 450-458页

作者： SHIN Sangmook bae Sung Yong Department of Naval Architecture and Marine Systems Engineering Pukyong National University Busan608-737 Korea

The hydroelasticity of water entry of an elastic wedge is simulated using a code developed using the flux-difference splitting scheme for immiscible and incompressible fluids and the hybrid Cartesian/immersed boundary method. The free surface is regarded as a moving contact discontinuity and is captured without any additional treatment along the interface. Immersed boundary nodes are distributed inside a fluid domain based on the edges that cross an instantaneous body boundary. Dependent variables are reconstructed at each immersed boundary node with the help of an interpolation along a local normal line for providing a boundary condition for a discretized flow problem. A dynamic beam equation is used for modeling the elastic deformation of a wedge. The developed code is validated through comparisons with other experimental and computational results for a free-falling wedge. The effects of the elastic deformation of the wedge on the pressure fields and time histories of the impact force are investigated in relation to the stiffness and density of the structure. Grid independence test is carried out for the computed time history of the force acting on an elastic wedge.

关键词： hydroelasticity free surface capturing non-boundary conforming method dynamic beam equation free falling impactforce