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Development of vehicle-recognition method on water surfaces using LiDAR data:SPD^(2)(spherically stratified point projection with diameter and distance)

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Defence Technology（防务技术） 2024年第6期36卷 95-104页

作者： Eon-ho Lee Hyeon Jun Jeon Jinwoo choi Hyun-Taek choi Sejin Lee The Department of Mechanical Engineering Kongju National University1223-24 Cheonan-daeroCheonan 31080Republic of Korea Ocean System Engineering Research Division Korea Research Institute of Ships and Ocean Engineering(KRISO)Daejeon 34103Republic of Korea The Division of Mechanical&Automotive Engineering Kongju National University1223-24 Cheonan-daeroCheonan 31080Republic of Korea

Swarm robot systems are an important application of autonomous unmanned surface vehicles on water *** monitoring natural environments and conducting security activities within a certain range using a surface vehicle,the swarm robot system is more efficient than the operation of a single object as the former can reduce cost and save *** is necessary to detect adjacent surface obstacles robustly to operate a cluster of unmanned surface *** this purpose,a LiDAR(light detection and ranging)sensor is used as it can simultaneously obtain 3D information for all directions,relatively robustly and accurately,irrespective of the surrounding environmental *** the GPS(global-positioning-system)error range exists,obtaining measurements of the surface-vessel position can still ensure stability during platoon *** this study,a three-layer convolutional neural network is applied to classify types of surface *** aim of this approach is to redefine the sparse 3D point cloud data as 2D image data with a connotative meaning and subsequently utilize this transformed data for object classification ***,we have proposed a descriptor that converts the 3D point cloud data into 2D image *** use this descriptor effectively,it is necessary to perform a clustering operation that separates the point clouds for each *** developed voxel-based clustering for the point cloud ***,using the descriptor,3D point cloud data can be converted into a 2D feature image,and the converted 2D image is provided as an input value to the *** intend to verify the validity of the proposed 3D point cloud feature descriptor by using experimental data in the ***,we explore the feasibility of real-time object classification within this framework.

关键词： Object classification Clustering 3D point cloud data LiDAR(light detection and ranging) Surface vehicle

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Noise reduction effect of airfoil and small-scale rotor using serration trailing edge in a wind tunnel test

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Science China(Technological Sciences) 2017年第2期60卷 325-332页

作者： RYI Jaeha choi Jong-Soo Department of Aerospace Engineering Chungnam National University Daejeon 305-764 Korea

This paper discussed a noise reduction effect of airfoil and small-scale model rotor by using attached serration trailing edge in the wind tunnel test condition. In order to analyze the changes in the performance due to the inclusion of a serrated trailing edge designed to reduce noise, a 10 k W wind turbine rotor was equipped with a thin serrated trailing edge. The restrictive condition for the serrated trailing edge equipped with the using of a 2D airfoil was examined through the using of a wind tunnel experiment after studying existing restrictive condition and analyzing prior research on serrated trailing edges. The aerodynamic performance and noise reduction effect of a small-scale model were investigated with the using of a serrated trailing edge. Moreover, the noise levels from the experiment were considered that the noise prediction method could be used for a full-scale rotor. It is confirmed that noise reduction effect is compared with wind tunnel test data at the 2D airfoil and model rotor condition.

关键词： wind turbine rotor wind tunnel experiment wind energy trailing edge serration noise reduction effect

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Honokiol attenuates oxidative stress-induced cytotoxicity in human keratinocytes via activating AMPK signaling

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Asian Pacific Journal of Tropical Biomedicine 2021年第5期11卷 222-230页

作者： Yung Hyun choi Anti-Aging Research Center Dong-eui UniversityBusan 47340Republic of Korea Department of Biochemistry College of Korean MedicineDong-eui UniversityBusan 47227Republic of Korea

Objective:To investigate the effect of honokiol on oxidative damage in HaCaT human ***:HaCaT cells were exposed to hydrogen peroxide(H_(2)O_(2)),following pretreatment with various concentrations of *** alleviating effects of honokiol on HaCaT cell viability and cell death,reactive oxygen species(ROS)production,DNA damage,mitochondrial dynamics,and inhibition of adenosine triphoaphate production against H_(2)O_(2)were *** blotting analysis was used to analyze the expression levels of specific ***:Honokiol suppressed H_(2)O_(2)-induced cytotoxicity and DNA damage by blocking abnormal ROS *** also prevented apoptosis by inhibiting loss of mitochondrial membrane potential and release of cytochrome c from the mitochondria into the cytosol,decreasing the Bax/Bcl-2 ratio,and reducing the activity of caspase-3 in H_(2)O_(2)-stimulated HaCaT *** addition,honokiol attenuated H_(2)O_(2)-induced reduction of adenosine triphosphate content,and activation of AMP-activated protein kinase(AMPK)was markedly promoted by honokiol in H_(2)O_(2)-stimulated ***,the anti-apoptosis and anti-proliferative activity of honokiol against H_(2)O_(2)was further enhanced by adding an activator of AMPK,indicating that honokiol activated AMPK in HaCaT keratinocytes to protect against oxidative ***:The present results indicate that honokiol may be useful as a potential therapeutic agent against various oxidative stress-related skin diseases.

关键词： Honokiol ROS DNA damage Apoptosis AMPK

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Ex situ aging effect on sulfonated poly(ether ether ketone) membrane:Hydration-dehydration cycling and hydrothermal treatment

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Journal of Energy Chemistry 2022年第7期31卷 583-592,I0014页

作者： Seung-Young choi Kyeong Sik Jin Polymer&Materials Chemistry Department of ChemistryLund UniversitySE-22100Sweden Center for Hydrogen·Fuel Cell Research Korea Institute of Science and Technology(KIST)Seoul 02792Republic of Korea Pohang Accelerator Laboratory Pohang University of Science and Technology(POSTECH)PohangKyungbuk 37673Republic of Korea

Prolonged hydrothermal treatment for sulfonated poly(ether ether ketone) membranes induces mechanical degradation and developing hydrophilic-hydrophobic phase separation, simultaneously. The enhanced phase separation provides incremental proton conductivity to the membranes, whereas mechanical degradation drastically reduces device stability. On this basis, we describe here the effects of two different ex situ aging processes on sulfonated poly(ether ether ketone) membranes: hydrationdehydration cycling and prolonged hydrothermal treatment. Both aged membranes exhibited enhanced phase separation under the hydrated conditions, as characterized by small angle X-ray ***, when the aged membranes were dried again, the nanostructure of the membranes aged via the hydration-dehydration cycling was recoverable, whereas that of the membranes aged via prolonged hydrothermal treatment was irreversible. Furthermore, the two differently aged membranes showed clear differences in thermal, mechanical, and electrochemical properties. Finally, we implemented both aged membranes in fuel cell application. The sample aged via hydration-dehydration cycling maintained its improved cell performance, whereas the sample aged via hydrothermal treatment showed drastically reduced cell performance after durability test for 50 h.

关键词： Sulfonated poly(ether ether ketone) Humidity cycle test Ex situ aging Proton exchange membrane Fuel cell

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Excellent dye degradation performance of FeSiBP amorphous alloys by Fenton-like process

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Journal of Environmental Sciences 2021年第7期33卷 116-127页

作者： Mingqing Zuo Seonghoon Yi Junhyeok choi Department of Materials Science and Metallurgical Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

Amorphous alloys are being newly applied in wastewater treatment because of their unique atomic packing *** possess excellent degradation efficiency,stability and *** this work,Fe_(80)Si_(10)B_(10) and Fe_(83)Si_(5)B_(8)P_(4) amorphous ribbons exhibited ad-vanced catalytic performance for the degradation of Methyl Blue(MB)and Rhodamine B(RhB)dyes,and the color removal reach nearly 100%within 11 min for both the ***-pared with the Fe_(80)Si_(10)B_(10) amorphous ribbon,the Fe_(83)Si_(5)B_(8)P_(4) ribbon showed higher degra-dation efficiency due to its lower reaction activation energy,higher electron transfer ability and higher Fe content,and the formation of the galvanic cell between the strong Fe-P bonds and the weak Fe-B *** also exhibited high stability and *** degradation ef-ficiency was improved when the appropriate concentration of H_(2)O_(2) is *** regards the pH,high degradation efficiency was observed in acidic MB solution,but it decreased as the pH increased up to pH *** application of the electro-Fenton-like process is discussed,which can effectively improve the degradation performance in a nearly natural *** study presents a high efficiency low-cost catalyst for synthetic dye degradation and expands the functional applications of Fe-based amorphous alloys.

关键词： Metallic glasses Azo dyes Advanced oxidation processes Decolorization Stability

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Location privacy protection of maritime mobile terminals

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Digital Communications and Networks 2022年第6期8卷 932-941页

作者： Xin Su Su Jiang Dongmin choi College of IOT Engineering Hohai UniversityChangzhou213022China Division of Undeclared Majors Chosun UniversityRepublic of Korea

Mobile Edge Computing(MEC)can support various high-reliability and low-delay applications in Maritime Networks(MNs).However,security risks in computing task offloading *** this study,the location privacy leakage risk of Maritime Mobile Terminals(MMTs)is quantified during task offloading and relevant Location Privacy Protection(LPP)schemes of MMT are considered under two kinds of task offloading *** single-MMT and single-time offloading scenario,a dynamic cache and spatial cloaking-based LPP(DS-CLP)algorithm is proposed;and under the multi-MMTs and multi-time offloading scenario,a pseudonym and alterable silent period-based LPP(PA-SLP)strategy is *** results show that the DS-CLP can save the response time and communication cost compared with traditional algorithms while protecting the MMT location ***,extending the alterable silent period,increasing the number of MMTs in the maritime area or improving the pseudonym update probability can enhance the LPP effect of MMTs in ***,the study results can be effectively applied to MNs with poor communication environments and relatively insufficient computing resources.

关键词： Location privacy protection Maritime network Mobile edge computing Task floading

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Distinctive differences in the granulation of saline and non-saline enriched anaerobic ammonia oxidizing(AMX)bacteria

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Journal of Environmental Sciences 2022年第12期34卷 162-173页

作者： Victory Fiifi Dsane Sumin An Younggyun choi Department of Environmental Engineering Chungnam National UniversityDaejeon 305-764Korea Department of Food Process Engineering University of GhanaLegonGhana Department of Environmental&IT Convergence Engineering Chungnam National UniversityDaejeon 305-764Korea

The growing interest in the anaerobic ammonium oxidizing(AMX)process in treating high nitrogen containing wastewaters and a comprehensive study into the granulation mechanism of these bacteria under diverse environmental conditions over the years have been *** this effect,the distinctive differences in saline adapted AMX(S_AMX)and nonsaline adapted AMX(NS_AMX)granules are presented in this *** was observed that substrate utilisation profiles,granule formation mechanism,and pace towards granulation differed marginally for the two adaptation *** different microbial dominant aggregation types aided in splitting the 471 days operated lab-scale SBRs into three distinct *** both reactors,phase III(granules dominant phase)showed the highest average nitrogen removal efficiency of 87.9%±4.8%and 85.6%±3.6%for the S_AMX and NS_AMX processes,*** extracellular polymeric substances(EPS)quantity and major composition determined its role either as a binding agent in granulation or a survival mechanism in saline *** was also observed that granules of the S_AMX reactor were mostly loosely and less condensed aggregates of smaller sub-units and flocs while those of the NS_AMX reactor were compact *** ionic gradient in saline enrichment led to an increased activity of the Na^(+)/K^(+)–ATPase,hence enriched granules produced higher cellular adenosine triphosphate molecules which finally improved the granules active biomass ratio by 32.96%.Microbial community showed that about three to four major known AMX species made up the granules consortia in both *** and expression of functional genes differed for these different species.

关键词： AMX Granulation EPS Enrichment Na^(+)/K^(+)-ATPase

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Advanced metal–organic frameworks for aqueous sodium-ion rechargeable batteries

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Journal of Energy Chemistry 2021年第2期30卷 396-406,I0014页

作者： Dongkyu choi Seonguk Lim Dongwook Han School of Nano Convergence Technology Hallym UniversityChuncheon 24252Gangwon-doRepublic of Korea Nano Convergence Technology Center Hallym UniversityChuncheon 24252Gangwon-doRepublic of Korea

Inexpensive and abundant sodium resources make energy storage systems using sodium chemistry promising replacements for typical lithium-ion rechargeable batteries(LIBs).Fortuitously,aqueous sodium-ion rechargeable batteries(ASIBs),which operate in aqueous electrolytes,are cheaper,safer,and more ionically conductive than batteries that operate in conventional organic electrolytes;furthermore,they are suitable for grid-scale energy storage *** electrode materials for storing Na~+ ions in ASIBs,a variety of multifunctional metal-organic frameworks(MOFs) have demonstrated great potential in terms of having porous 3 D crystal structures,compatibility with aqueous solutions,long cycle lives(≥1000 cycles),and ease of *** present review describes MOF-derived technologies for the successful application of MOFs to ASIBs and suggests future challenges in this area of research based on the current understanding.

关键词： Metal–Organic Framework(MOF) Prussian blue Metal hexacyanoferrate Aqueous electrolyte Sodium-ion Rechargeable battery

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Effect of change of sand properties on travel distance of ricocheted debris

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Defence Technology（防务技术） 2021年第4期17卷 1486-1495页

作者： Yoon Keon Kim Woo Chun choi Department of Mechanical Engineering Korea University145 Anam-roSeongbuk-guSeoul02841Republic of Korea

The debris from exploded buildings can ricochet after colliding with the ground,thus increasing the debris travel distance and danger from any associated impacts or *** reduce this danger,the travel distance of ricocheted debris must be accurately *** study analyzed the change in the travel distance of ricocheted concrete debris relative to changes in the properties of a sand *** shear tests were conducted to measure the change in internal friction angle as a function of temperature and water content of the *** element analysis(FEA)was then applied to these variables to predict the speed and angle of the debris after *** FEA results were compared with results of low-speed ricochet experiments,which employed variable temperature and water *** travel distance of the debris was calculated using MATLAB,via trajectory equations considering the drag *** the internal friction angle decreased,the shear stress decreased,leading to deeper penetration of the debris into the *** the loss of kinetic energy increased,the velocity and travel distance of the ricocheted debris *** in the ricochet velocity and travel distance of the debris,according to changes in the internal friction angle,indicated that the debris was affected by the environment.

关键词： Ricochet Exploded debirs Environmental change Sand Temperature Water content Internal friction angle Travel distance

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Applicability of cement-based grout for ground heat exchanger considering heating-cooling cycles

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Science China(Technological Sciences) 2011年第7期54卷 1661-1667页

作者： Moonseo PARK SunhongMIN Jeehee LIM Jong Min choi Hangseok choi School of civil Environmental and Architectural Engineering Korea University Seoul Republic of Korea Department of Mechanical Engineering Hanbat National University Daejeon Republic of Korea

The applicability of cement grout （or cement-based grout） has been considered as an alternative to bentonite grout commonly used to backfill closed-loop vertical ground heat exchangers. In a geothermal heat pump system, repeated heating-cooling cycles may cause adverse effects on the integrity of cement grout in the ground heat exchanger. To account for the temperature cycling effect, the strength degradation of cement grout due to temperature cycling has been examined by measuring the unconfined compression strength of cured specimens in a humidity-temperature controlling chamber with applying temperature cycles between -5℃ and 50℃. There is a tendency that the unconfined compression strength decreases with an increase in the number of temperature cycles. On the other hand, an equivalent hydraulic conductivity of a pipe-embedded cement grout specimen was evaluated by carrying out a modified flexible wall permeameter test equipped with a water circulating system to control temperature inside the pipe section. The applied operating temperature range was from 5 to 35℃. After three cycles of heating-cooling circulation, the equivalent hydraulic conductivity becomes asymptotic to a constant value, which implies there is no severe detachment of the pipe from the cement grout.

关键词： cement grout bentonite grout thermal conductivity workability equivalent permeability coefficient

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