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Disordered Structure and Reversible Phase Transformation from K-Birnessite to Zn-Buserite Enable High-Performance Aqueous Zinc-lon Batteries

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Energy & Environmental Materials 2024年第3期7卷 100-111页

作者： Nibagani Naresh Suyoon Eom Sang Jun Lee Su Hwan Jeong Ji-Won Jung Young Hwa Jung Joo-Hyung kim Department of Materials Engineering and Convergence Technology Gyeongsang National University(GNU)Jinju 52828South Korea School of Material Science and Engineering(Ceramic Engineering) Gyeongsang National University(GNU)Jinju 52828South Korea School of Materials Science and Engineering University of Ulsan(UOU)Ulsan 44776South Korea PLS-ⅡBeamline Division Pohang Accelerator Laboratory(PAL)Pohang 37673South Korea

The layeredδ-MnO_(2)(dMO)is an excellent cathode material for rechargeable aqueous zinc-ion batteries owing to its large interlayer distance(~0.7 nm),high capacity,and low cost;however,such cathodes suffer from structural degradation during the long-term cycling process,leading to capacity *** this study,a Co-doped dMO composite with reduced graphene oxide(gC-dMO)is developed using a simple cost-effective hydrothermal *** degree of disorderness increases owing to the hetero-atom doping and graphene oxide *** is demonstrated that layered dMO and gC-dMO undergo a structural transition from K-birnessite to the Zn-buserite phase upon the first discharge,which enhances the intercalation of Zn^(2+)ions,H_(2)O molecules in the layered *** gC-dMO cathode exhibits an excellent capacity of 302 mAh g^(-1)at a current density of 100 mAg^(-1)after 100 cycles as compared with the dMO cathode(159 mAhg^(-1)).The excellent electrochemical performance of the gC-dMO cathode owing to Co-doping and graphene oxide sheets enhances the interlayer gap and disorderness,and maintains structural stability,which facilitates the easy reverse intercalation and de-intercalation of Zn^(2+)ions and H_(2)O ***,gC-dMO is a promising cathode material for large-scale aqueous ZIBs.

关键词： aqueous zinc-ion batteries birnessite buserite disordered structure phase transformation

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Effects of a Building’s Density on Flow in Urban Areas

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Advances in Atmospheric Sciences 2009年第1期26卷 45-56页

作者： Jae-Jin kim do-Yong kim Department of Environmental Atmospheric Sciences Pukyong National University Busan Korea Center for Atmosphere Science and Earthquake Research Korea Meteorological Administration Busan Korea

The effects of a building＇s density on urban flows are investigated using a CFD model with the RNg k - ε turbulence closure scheme. Twenty-seven cases with different building＇s density parameters （e.g., building and street-canyon aspect ratios） are numerically simulated. As the building＇s density parameters vary, different flow regimes appear. When the street canyon is relatively narrow and high, two counterrotating vortices in the vertical direction are generated. The wind speed along streets is mainly affected by the building＇s length. However, it is very difficult to find or generalize the characteristics of the street-canyon flows in terms of a single building＇s density parameter. This is because the complicated flow patterns appear due to the variation of the vortex structure and vortex number. Volume-averaged vorticity magnitude is a very good indicator to reflect the flow characteristics despite the strong dependency of flows on the variation of the building＇s density parameters. Multi-linear regression shows that the volume-averaged vorticity magnitude is a strong function of the building＇s length and the street-canyon width. The increase in the building＇s length decreases the vorticity of the street-canyon flow, while, the increase in the street- canyon width increases the vorticity.

关键词： urban flow characteristics building's density parameter volume-averaged vorticity CFD model

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Feasibility of wear reduction for soft nanostructured thin film through enhanced elastic recoverability and contact stress relief

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Friction 2023年第7期11卷 1292-1306页

作者： Kuk-Jin seo Hyun-Joon kim Dae-Eun kim Department of Mechanical Engineering Yonsei UniversitySeoul 03722Republic of Korea Department of Precision Mechanical Engineering Kyungpook National UniversitySangju 37224Republic of Korea Department of Advanced Science and Technology Convergence Kyungpook National UniversitySangju 37224Republic of Korea

This work shows that a soft,thin film comprising randomly aligned carbon nanotubes(CNTs)can reduce surface wear more effectively than a homogeneous thin film because of enhanced elastic recoverability and contact stress relief originating from its mesh *** investigate the wear characteristics of the mesh structure compared to those of the homogeneous thin film,multi-walled CNTs(MWCNTs)and diamond-like carbon(DLC)thin films were prepared to conduct nanoscale tribological experiments using the atomic force microscopy(AFM).The MWCNT thin film showed unmeasurably low wear compared with the DLC thin film under a certain range of normal *** demonstrate the wear reduction mechanism of the MWCNT thin film,its indentation and frictional behaviors were *** indentation behavior of the MWCNT thin film revealed repetitive elastic deformation with a wide strain range and a significantly lower elastic modulus than that of the DLC thin *** permanent deformation of the MWCNT thin film was observed through frictional experiments under relatively high normal load *** results are expected to provide insights into the design of highly wear-resistant surfaces using nanostructures.

关键词： carbon nanotube(CNT) thin film wear friction elastic recovery

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Multimodal treatments of right gastroepiploic arterial leiomyosarcoma with hepatic metastasis:A case report and review of the literature

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World Journal of Clinical Cases 2018年第8期6卷 219-223页

作者： Hyung-Il seo do.g-Il kim Youngsoo Chung Chang In Choi Minjoo kim Sungpil Yun Suk kim do Youn Park Department of Surgery Biomedical Research InstitutePusan National University Hospital Department of Surgery Pusan National University Yangsan Hospital Department of Surgery On Hospital Department of Radiology Biomedical Research Institute Pusan National University Hospital Department of Pathology Biomedical Research Institute Pusan National University Hospital

Leiomyosarcoma of an artery is very rare, and cases with hepatic metastasis are even rarer. We describe a case of a 70-year-old man who after follow up due to rectal cancer, presented with an intra-abdominal hypervascular mass and a hepatic mass. After surgical resection, it was diagnosed as a leiomyosarcoma of the right gastroepiploic artery with hepatic metastasis. Multiple metastases had recurred at the liver. He has survived more than 53 mo through multimodal treatments(three surgical resections, radiofrequency ablation, transarterial chemoembolization, chemotherapies, and targeted therapy). Multimodal treatments, including active surgical resection, may behelpful in the treatment of aggressive diseases such as arterial leiomyosarcoma with metastasis.

关键词： Multimodal treatments Intra-abdominal arterial leiomyosarcoma Hepatic metastasis Arterial leiomyosarcoma Surgical resection

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A Synthesis of Multi-Precision Multiplication and Squaring Techniques for 8-Bit Sensor Nodes＂ State-of-the-Art Research and Future Challenges

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Journal of Computer Science & Technology 2016年第2期31卷 284-299页

作者： Zhe Liu Hwajeong seo Howon kim Laboratory of Algorithmics Cryptology and Security University of Luxembourg Kirchberg L-1359 Luxembourg School of Computer Science and Engineering Pusan National University Busan 609-735 Korea

Multi-precision multiplication and squaring are the performance-critical operations for the implementation of public-key cryptography, such as exponentiation in RSA, and scalar multiplication in elliptic curve cryptography （ECC）. In this paper, we provide a survey on the multi-precision multiplication and squaring techniques, and make special focus on the comparison of their performance and memory footprint on sensor nodes using 8-bit processors, Different from the previous work, our advantages are in at least three aspects. Firstly, this survey includes the existing techniques for multi- precision multiplication and squaring on sensor nodes over prime fields. Secondly, we analyze and evaluate each method in a systematic and objective way. Thirdly, this survey also provides suggestions for selecting appropriate multiplication and squaring techniques for concrete implementation of public-key cryptography. At the end of this survey, we propose the research challenges on efficient implementation of the multiplication and the squaring operations based on our observation.

关键词： public-key cryptography multi-precision multiplication multi-precision squaring 8-bit AVR microprocessor

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Experimental Study on Drag-induced Balancing via a Static Tail for Water-running Robots

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Journal of Bionic Engineering 2016年第4期13卷 537-543页

作者： do.ggyu Lee Hyungyu kim TaeWon seo School of Mechanical Engineering Yeungnam University Gyeongsan 712-749 Republic of Korea

Robotics is one area of research in which bio-inspiration is an effective way to design a system by investigating the working principles of nature. Recently, tails have received interest in robotics to increase stability and maneuverability. In this study, we investigated the effectiveness of a static tail for bio-inspired water-running locomotion. The tail was added to increase the stability in the rolling and yawing directions based on the hydrodynamic force from interaction between the tail and the water. The drag coefficient in the interaction is not easy to calculate analytically, so experimental studies were done for various static tail shapes. Five different shapes and compliances in two directions were considered for experimental design candidates. The result was applied to design a stable amphibious robot that can run on ground and water surfaces.

关键词： bio-inspiration water-running robot static tail stability hydrodynamic balancing basilisk lizard

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Analysis and Experiment on the Steering Control of a Water-running Robot Using Hydrodynamic Forces

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Journal of Bionic Engineering 2017年第1期14卷 34-46页

作者： Hyungyu kim Kyungmin Jeong TaeWon seo School of Mechanical Engineering Yeungnam University Gyeongsan 712-749 Republic of Korea Nuclear Convergence Technology Division Korea Atomic Energy. Research Institute Daejeon 305-353 Republic of Korea

Steering is important for the high maneuverability of mobile robots. Many studies have been performed to improve the maneuverability using a tail. The aim of this research was to verify the performance of a water-running robot steering on water using a tail. Kinematic analysis was performed for the leg mechanism and the interaction forces between the water and the feet to calculate the propulsive drag force of the water. This paper suggests a simplified planar two-link rigid body model to determine the dynamic performance of the robotic platform with respect to the effect of the tail＇s motion. Simulations based on a dynamic model were performed by applying a range of motions to the tail. In addition, a simulation with a Bang-bang controller was also performed to control the main frame＇s yawing locomotion. Finally, an experiment was conducted with the controller, and the simulation and experimental results were compared. These results can be used as a guideline to develop a steerable water-running robot.

关键词： basilisk lizard water-running robot steering Static Tail (ST) Dynamic Tail (DT) planar two-link rigid body

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Peri-Net-Pro: the neural processes with quantified uncertainty for crack patterns

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Applied Mathematics and Mechanics(English Edition) 2023年第7期44卷 1085-1100页

作者： M.kim g.LIN Samsung Electronics Yongin-siGyeonggi-do 17113Republic of Korea Department of Mathematics Purdue UniversityWest LafayetteIN 47907-2067U.S.A. School of Mechanical Engineering Purdue UniversityWest LafayetteIN 47907-2067U.S.A.

This paper develops a deep learning tool based on neural processes(NPs)called the Peri-Net-Pro,to predict the crack patterns in a moving disk and classifies them according to the classification modes with quantified *** particular,image classification and regression studies are conducted by means of convolutional neural networks(CNNs)and ***,the amount and quality of the data are enhanced by using peridynamics to theoretically compensate for the problems of the finite element method(FEM)in generating crack pattern ***,case studies are conducted with the prototype microelastic brittle(PMB),linear peridynamic solid(LPS),and viscoelastic solid(VES)models obtained by using the peridynamic *** case studies are performed to classify the images by using CNNs and determine the suitability of the PMB,LBS,and VES ***,a regression analysis is performed on the crack pattern images with NPs to predict the crack *** regression analysis results confirm that the variance decreases when the number of epochs increases by using the *** training results gradually improve,and the variance ranges decrease to less than *** main finding of this study is that the NPs enable accurate predictions,even with missing or insufficient training *** results demonstrate that if the context points are set to the 10th,100th,300th,and 784th,the training information is deliberately omitted for the context points of the 10th,100th,and 300th,and the predictions are different when the context points are significantly ***,the comparison of the results of the 100th and 784th context points shows that the predicted results are similar because of the gaussian processes in the ***,if the NPs are employed for training,the missing information of the training data can be supplemented to predict the results.

关键词： neural process(NP) peridynamics crack pattern molecular dynamic(MD)simulation machine learning gaussian process regression convolutional neural network(CNN)

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Long cycle-life aqueous Zn battery enabled by facile carbon nanotube coating on Cu current collector

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Carbon Energy 2024年第6期6卷 151-164页

作者： Beom-Keun Cho Sung-Ho Huh So Hee kim Seungho Yu Jong-seo.g Bae Jung-Keun Yoo Seung-Ho Yu Department of Chemical and Biological Engineering Korea UniversitySeoulRepublic of Korea Advanced Analysis Center Korea Institute of Science and Technology(KIST)SeoulRepublic of Korea Energy Storage Research Center Korea Institute of Science and Technology(KIST)SeoulRepublic of Korea KIST School Division of Energy and Environment TechnologyKorea University of Science and TechnologySeoulRepublic of Korea Busan Center Korea Basic Science Institute(KBSI)BusanRepublic of Korea Carbon Composites Department Composites Research DivisionKorea Institute of Materials Science(KIMS)ChangwonRepublic of Korea

As an alternative to Li-ion batteries,aqueous Zn batteries have gained attention due to the abundance of Zn metal,low reduction potential(-0.76 V *** hydrogen electrode),and high theoretical capacity(820 mAh g^(-1))of multivalent Zn2+***,the growth of Zn dendrites and the formation of irreversible surface reaction byproducts pose challenges for ensuring a long battery lifespan and ***,the Cu foil coated with a single-walled carbon nanotube(SWCNT)layer using a facile doctor blade casting method is *** SWCNT-coated Cu foil demonstrates a significantly longer battery lifespan compared to the bare Cu in the half-cell *** operando optical microscopy imaging,we are able to provide intuitive evidence that Zn deposition occurs between the carbon nanotube(CNT)coating and Cu substrate,in agreement with the computational ***,with various imaging techniques,the flat morphology and homogeneous distribution of Zn beneath the SWCNT layer are *** addition,the full-cell using CNT-coated Cu exhibits a long cycle life compared to the control group,thereby demonstrating improved electrochemical performance with limited Zn for the cycling process.

关键词： aqueous Zn battery carbon nanotube operando imaging surface coating

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Effectiveness Analysis of DVFS and DPM in Mobile Devices

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Journal of Computer Science & Technology 2012年第4期27卷 781-790页

作者： Youngbin seo Jeongki kim Euiseo.g seo Computer Science and Engineering Major University of Science and Technology217 Gajeong-roYuseong-guDaejeon 305-350Korea Electronics and Communications Research Institute 138 GajengnoYuseong-guDaejeonKorea College of Information and Communication Engineering Sungkyunkwan University2066 Seubu-roJangan-gu Suwon 440-746Korea

The demand for high-performance embedded processors in multimedia mobile electronics is growing and their power consumption thus increasingly threatens battery lifetime. It is usually believed that the dynamic voltage and frequency scaling （DVFS） feature saves significant energy by changing the performance levels of processors to match the performance demands of applications on the fly. However, because the energy efficiency of embedded processors is rapidly improving, the effectiveness of DVFS is expected to change. In this paper, we analyze the benefit of DVFS in state-of-the-art mobile embedded platforms in comparison to those in servers or PCs. To obtain a clearer view of the relationship between power and performance, we develop a measurement methodology that can synchronize time series for power consumption with those for processor utilization. The results show that DVFS hardly improves the energy efficiency of mobile multimedia electronics, and can even significantly worsen energy efficiency and performance in some cases. According to this observation, we suggest that power management for mobile electronics should concentrate on adaptive and intelligent power management for peripherM devices. As a preliminary design, we implement an adaptive network interface card （NIC） speed control that reduces power consumption by 1070 when NIC is not heavily used. Our results provide valuable insights into the design of power management schemes for future mobile embedded systems.

关键词： dynamic voltage scaling power management battery management energy eiffciency smart phone

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