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Effects of Microstructure of Aluminum Substrate on Ordered Nanopore Arrays in Anodic Alumina

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Journal of Materials Science & Technology 2015年第7期31卷 751-758页

作者： choong-Soo Chi Jong-Ho Lee Insoo Kim han-Jun Oh School of Advanced Materials Engineering Kookmin University Department of Chemistry Hanseo University Advanced Materials Science and Engineering Kumoh National Institute of Technology Department of Materials Science Hanseo University

The effects of microstructure of aluminum substrate on regular nanopore arrangement in anodic alumina layer were investigated. The dissimilar microstructure and texture on aluminum sheets were prepared by various cold rollings and heat treatments, and anodic alumina nanoporous layers were fabricated by two step anodizing method at 40 V in oxalic acid solution. For the aluminum sheets with similar surface texture and annealing condition except purity, the regularity of the nanopore arrangement on the anodic alumina layer increased with purity of aluminum substrate. The difference of surface texture on AI sheets is not critical parameter for formation of ordered nanopore array compared with purity and heat treatment of substrate aluminum. The investigation suggested that the purity and reasonable annealing temperature of aluminum substrate are very important process to obtain the highly-ordered nanopore array on anodic alumina layer.

关键词： AnodizationNanoporous structureTextureAluminum alloy

Postmortem ^(7)Li NMR analysis for assessing the reversibility of lithium metal electrodes in lithium metal batteries

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Journal of Energy Chemistry 2024年第7期94卷 430-440页

作者： Jaewon Baek Sunha Kim hee-Tak Kim Oc hee han Department of Chemical&Biomolecular Engineering KAISTDaejeon 34141Republic of Korea Metropolitan Seoul Center Korea Basic Science InstituteSeoul 03759Republic of Korea Graduate School of Analytical Science&Technology Chungnam National UniversityDaejeon 34134Republic of Korea

Despite the proficiency of lithium(Li)-7 NMR spectroscopy in delineating the physical and chemical states of Li metal electrodes,challenges in specimen preparation and interpretation impede its *** this study,we conducted a comprehensive postmortem analysis utilizing ^(7)Li NMR,employing a stan-dard magic angle spinning probe to examine protective-layer coated Li metal electrodes and LiAg alloy electrodes against bare Li metal electrodes within Li metal batteries(LMBs).Our investigation explores the effects of sample burrs,alignment with the magnetic field,the existence of liquid electrolytes,and precycling on the ^(7)Li NMR *** contrasting NMR spectra before and after cycling,we identi-fied alterations in Li^(0) and Li^(+) signals attributable to the degradation of the Li metal *** NMR analyses decisively demonstrate the efficacy of the protective layer in mitigating dendrite and solid elec-trolyte interphase ***,we noted that Li*ions near the Li metal surface exhibit magnetic susceptibility anisotropy,revealing a novel approach to studying diamagnetic species on Li metal elec-trodes in *** study provides valuable insights and practical guidelines for characterizing distinct lithium states within LMBs.

关键词： NMR spectroscopy Lithium-7 Lithium metal battery Electrolyte Electrode-protective layer Solid electrolyte interface Magnetic susceptibility anisotropy Lithium-metal NMR signal Diamagnetic^(7)Li NMR signal

A Review on Interface Engineering of MXenes for Perovskite Solar Cells

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Nano-Micro Letters 2023年第8期15卷 270-308页

作者： Srikanta Palei G.Murali choong‑hee Kim Insik In Seul‑Yi Lee Soo‑Jin Park Department of Chemistry Inha University100 InharoIncheon 22212South Korea Department of Polymer Science and Engineering Department of IT‑Energy Convergence(BK21 Four)Chemical Industry InstituteKorea National University of TransportationChungju 27469South Korea

With an excellent power conversion efficiency of 25.7%,closer to the Shockley–Queisser limit,perovskite solar cells(PSCs)have become a strong candidate for a next-generation energy ***,the lack of stability and reliability in PSCs remained challenging for ***,such as interfacial and structural engineering,have a more critical influence on enhanced ***,two-dimensional materials,have emerged as promising materials in solar cell applications due to their metallic electrical conductivity,high carrier mobility,excellent optical transparency,wide tunable work function,and superior mechanical *** to different choices of transition elements and surface-terminating functional groups,MXenes possess the feature of tuning the work function,which is an essential metric for band energy alignment between the absorber layer and the charge transport layers for charge carrier extraction and collection in ***,adopting MXenes to their respective components helps reduce the interfacial recombination resistance and provides smooth charge transfer paths,leading to enhanced conductivity and operational stability of *** review paper aims to provide an overview of the applications of MXenes as components,classified according to their roles as additives(into the perovskite absorber layer,charge transport layers,and electrodes)and themselves alone or as interfacial layers,and their significant importance in PSCs in terms of device performance and ***,we discuss the present research status and future directions toward its use in PSCs.

关键词： MXenes Perovskite solar cells Additives Interfacial layer Electrodes

Determining node duty cycle using Q-learning and linear regression for WSN

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Frontiers of Computer Science 2021年第1期15卷 17-23页

作者： han Yao HUANG Kyung Tae KIM hee Yong YOUN College of Software Sungkyunkwan UniversitySuwon 440-746Korea

Wireless sensor network(WSN)is effective for monitoring the target environment,which consists of a large number of sensor nodes of limited *** efficient medium access control(MAC)protocol is thus imperative to maximize the energy efficiency and performance of *** most existing MAC protocols are based on the scheduling of sleep and active period of the nodes,and do not consider the relationship between the load condition and *** this paper a novel scheme is proposed to properly determine the duty cycle of the WSN nodes according to the load,which employs the Q-leaming technique and function approximation with linear *** allows low-latency energy-efficient scheduling for a wide range of traffic conditions,and effectively overcomes the limitation of Q-learning with the problem of continuous state-action ***3 simulation reveals that the proposed scheme significantly improves the throughput,latency,and energy efficiency compared to the existing fully active scheme and S-MAC.

关键词： wireless sensor network media access control duty-cycle scheduling Q-leaming linear regression

A GIS-Based Framework for Real-Time Debris-Flow Hazard Assessment for Expressways in Korea

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International Journal of Disaster Risk Science 2016年第3期7卷 293-311页

作者： han-Saem Kim choong-Ki Chung Sang-Rae Kim Kyung-Suk Kim Earthquake Research Center Korea Institute of Geoscience and Mineral Resources Department of Civil and Environmental Engineering Seoul National University Department of Civil and Environmental Engineering Northwestern University Expressway and Transportation Research Institute Korea Expressway Corporation

Debris flows caused by heavy rainfall in mountain areas near expressways lead to severe social and economic losses and sometimes result in ***, the development of a real-time system for debris-flow hazard assessment is necessary to provide preliminary information for rapid decision making about evacuations or restoration measures, as well as to prevent secondary disasters caused by debris flows. Recently,various map-based approaches have been proposed using multi-attribute criteria and assessment methods for debrisflow susceptibilities. For the macrozonation of debris-flow hazard at a national scale, a simplified method such as the Korea Expressway Corporation(KEC) debris-flow hazard assessment method can be applied for systematic analysis based on geographic information systems(GIS) and monitoring networks. In this study, a GIS-based framework of real-time debris-flow hazard assessment for expressway sections is proposed based on the KEC debris-flow hazard assessment method. First, the KEC-based method was standardized in a systematic fashion using Arc GIS,enabling the objective and quantitative acquisition of various attribute datasets. The quantification of rainfall criteria also was considered. A safety management system for debris-flow hazard was developed based on the GIS platform. Finally, the method was applied and verified on three expressway sections in Korea. The grading standard for each individual influencing attribute was subsequently modified to more accurately assess the debris-flow hazards.

关键词： Debris-flow hazard Expressway management GIS Korea Real-time hazard assessment

Facile synthesis of graphitic carbon-nitride supported antimony-doped tin oxide nanocomposite and its application for the adsorption of volatile organic compounds

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Journal of Environmental Sciences 2019年第5期31卷 35-42页

作者： Devi Prashad Ojha Jun hee Song han Joo Kim Department of Convergence Technology Engineering Chonbuk National University Eco-friendly Machine Parts Design Center Chonbuk National University

Antimony-doped tin oxide(ATO) nanoparticles with an average size of ～ 6 nm were prepared by co-precipitation and subsequent heat treatment. Graphitic carbon nitride(g-CN)/ATO hybrid nanocomposite was designed by the combination of thermally synthesized g-CN and ATO nanoparticles by ultrasonication. The materials were characterized using N2 adsorption/desorption(BET), X-ray diffraction(XRD), scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), transmission electron microscopy(TEM) and Fourier transform infrared spectroscopy(FTIR). A mixture of five volatile organic compounds(VOCs, chloroform, benzene, toluene, xylene and styrene) was used to compare the adsorption capacity of the samples. The adsorption capacity of ATO nanoparticles was improved by the addition of g-CN. Experimental data showed that, among the five VOCs,chloroform was the least adsorbed, regardless of the samples. The g-CN/ATO showed nearly three times greater adsorption capacity for the VOC mixture than pure ATO. The unchanged efficiency of VOC adsorption during cyclic use demonstrated the completely reversible adsorption and desorption behavior of the nanocomposite at room conditions. This economically and environmentally friendly material can be a practical solution for outdoor and indoor VOC removal.

关键词： Antimony-doped tin oxide(ATO) Graphitic carbon nitride(g-CN) Volatile organic compounds(VOC) Adsorption

Selecting suitable sites for mountain ginseng(Panax ginseng)cultivation by using geographically weighted logistic regression

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Journal of Mountain Science 2017年第3期14卷 492-500页

作者： han hee JANG Kwang-min CHUNG Joo-sang Department of Forest Engineering Resources and ManagementCollege of ForestryOregon State UniversityCorvallisOR 97331USA Department of Forest Sciences College of Agriculture and Life SciencesSeoul National UniversitySeoul 08826Republic of Korea Research Institute for Agriculture and Life Sciences Seoul National UniversitySeoul 08826Republic of Korea

With the well-being trends to pursue a healthy life, mountain ginseng(Panax ginseng) is rising as one of the most profitable forest products in South Korea. This study was aimed at evaluating a new methodology for identifying suitable sites for mountain ginseng cultivation in the country. Forest vegetation data were collected from 46 sites and the spatial distribution of all sites was analyzed using GIS data for topographic position, landform, solar radiation, and topographic wetness. The physical and chemical properties of the soil samples, including moisture content, p H, organic matter, total nitrogen, exchangeable cations, available phosphorous, and soil texture, were analyzed. The cultivation suitability at each site was assessed based on the environmental conditions using logistic regression(LR) and geographically weighted logistic regression(GWLR) and the results of both methods were compared. The results show that the areas with northern aspect and higher levels of solar radiation, moisture content, total nitrogen, and sand ratio are more likely to be identified as suitable sites for ginseng cultivation. In contrast to the LR, the spatial modeling with the GWLR results in an increase in the model fitness and indicates that a significant portion of spatialautocorrelation in the data decreases. A higher value of the area under the receiver operating characteristic(ROC) curve presents a better prediction accuracy of site suitability by the GWLR. The geographically weighted coefficient estimates of the model are nonstationary, and reveal that different site suitability is associated with the geographical location of the forest stands. The GWLR increases the accuracy of selecting suitable sites by considering the geographical variations in the characteristics of the cultivation sites.

关键词： Panax ginseng Site suitability Logistic regression Geographically weighted logistic regression Geographic Information System South Korea

Ischemic colitis after enema administration: Incidence, timing, and clinical features

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World Journal of Gastroenterology 2020年第41期26卷 6442-6454页

作者： Yura Ahn Gil-Sun Hong Ju hee Lee choong Wook Lee Seon-Ok Kim Department of Radiology and Research Institute of Radiology University of Ulsan College of Medicine&Asan Medical CenterSeoul 05505South Korea Department of Clinical Epidemiology and Biostatistics Asan Medical CenterUniversity of Ulsan College of MedicineSeoul 05505South Korea

BACKGROUND Enema administration is a common procedure in the emergency department(ED). However, several published case reports on enema-related ischemic colitis(IC) have raised the concerns regarding the safety of enema agents. Nevertheless, information on its true incidence and characteristics are still *** To investigate the incidence, timing, and risk factors of IC in patients receiving *** We consecutively collected the data of all adult patients receiving various enema administrations in the ED from January 2010 to December 2018 and identified patients confirmed with IC following enema. Of 8320 patients receiving glycerin enema, 19 diagnosed of IC were compared with an age-matched control group without *** The incidence of IC was 0.23% among 8320 patients receiving glycerin enema;however, there was no occurrence of IC among those who used other enema agents. The mean age ± standard deviation(SD) of patients with glycerin enemarelated IC was 70.2 ± 11.7. The mean time interval ± SD from glycerin enema administration to IC occurrence was 5.5 h ± 3.9 h(range 1-15 h). Of the 19 glycerin enema-related IC cases, 15(79.0%) were diagnosed within 8 h. The independent risk factors for glycerin-related IC were the constipation score [Odds ratio(OR), 2.0;95% confidence interval(CI): 1.1-3.5, P = 0.017] and leukocytosis(OR, 4.5;95%CI: 1.4-14.7, P = 0.012).CONCLUSION The incidence of glycerin enema-related IC was 0.23% and occurred mostly in the elderly in the early period following enema administration. Glycerin enemarelated IC was associated with the constipation score and leukocytosis.

关键词： Enema Glycerin Ischemic colitis Incidence Timing Risk factors

Asymptotic Results for Random Processes

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Acta Mathematicae Applicatae Sinica 2017年第2期33卷 363-372页

作者： hee-JIN MOON ChanG-HO han YONG-KAB CHOI Department of Mathematics and RINS Gyeongsang National University Jinju 660-701 South Korea

In this paper we establish asymptotic results and a generalized uniform law of the iterated logarithm （LIL） for the increments of a strictly stationary random process, whose results are proved by separating linearly positive quadrant dependent （LPQD） random process and linearly negative quadrant dependent （LNQD） one, respectively.

关键词： quadrant dependence stationary random process law of the iterated logarithm