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Permeability evaluation for artificial single rock fracture according to geometric aperture variation using electrical resistivity

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journal of Rock Mechanics and Geotechnical Engineering 2021年第4期13卷 787-797页

作者： Hangbok Lee jong-Won Lee Tae-Min Oh Deep Subsurface Research Center Korea Institute of Geoscience and Mineral ResourcesDaejeon34132Republic of Korea Department of Civil and Environmental Engineering Pusan National UniversityBusan46241Republic of Korea

A convenient approach was proposed by which to evaluate and monitor the permeability of a rock fracture by verifying the quantitative correlation between the electrical resistivity and permeability at laboratory *** this purpose,an electrical resistivity measurement system was applied to the laboratory experiments using artificial cells with the shape of a single rock *** experiments were conducted using rock fractures according to the geometry,aperture sizes,wavelengths,and roughness *** overall negative relationship between the normalized electrical resistivity values and the aperture sizes directly linked with the permeability,was well fitted by the power-law function with a large determination coefficient(≈0.86).The effects of wavelength and roughness amplitude of the rock fracture on the electrical resistivity were also *** showed that the electrical resistivity was slightly increased with decreasing wavelength and increasing roughness *** empirical model for evaluating the permeability of a rock fracture was proposed based on the experimental *** the field,if the electrical resistivity of pore groundwater could be measured in advance,this empirical model could be applied effectively for simple,quick monitoring of the fracture *** uncertainty may be associated with the permeability estimation due to the limited control parameters considered in this research,this electrical resistivity approach could be helpful to monitor the rock permeability in deep underground facilities such as those used for radioactive waste repositories or forms of energy storage.

关键词： Permeability Rock fracture Electrical resistivity fracture geometry Long-term monitoring

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Effects of surface roughness on bending properties of rolled AZ31 alloy

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journal of Magnesium and Alloys 2023年第4期11卷 1224-1235页

作者： Gyo Myeong Lee jong Un Lee Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

This study investigated the effects of mechanical-polishing-induced surface roughness and the direction of polishing lines on the bending properties of a rolled AZ31 *** this end,three-point bending tests were performed on one sample without polishing lines(SS sample)and two samples with polishing lines—one in which the polishing lines were parallel to the rolling direction(RS-RD sample)and the other in which they were parallel to the transverse direction(RS-TD sample).In all three samples,macrocracks were formed in the width direction on the outer surface,where tensile stress was predominantly generated in the longitudinal ***,the macrocracks formed in the SS sample were curved because of the merging of uniformly formed fine microcracks,whereas those formed in the RS-TD sample were linear owing to the formation of relatively coarse microcracks along the polishing *** bendability of the samples was in the order of SS>RS-RD>RS-TD,and their limiting bending depths were 4.8,4.6,and 4.4 mm,*** the presence of mechanical-polishing-induced surface roughness,polishing lines perpendicular to the direction of the major stress(i.e.,tensile stress along the longitudinal direction)resulted in a greater degree of stress concentration on the outer surface of the bending *** higher stress concentration promoted the formation of undesirable{10–11}contraction and{10–11}–{10–12}double twins—which typically act as crack initiation sites—and thereby facilitated crack generation and ***,the surface roughness caused premature fracture during bending deformation,which,in turn,caused deterioration of the bendability of the rolled Mg alloy.

关键词： AZ31 alloy Bending Surface roughness Stress concentration Crack

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Bending properties of extruded AZ91–0.9Ca–0.6Y alloy and their improvement through precompression and annealing

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journal of Magnesium and Alloys 2022年第8期10卷 2238-2251页

作者： jong Un Lee Gyo Myeong Lee Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

In this study,an extruded Mg–9Al–1Zn–0.3Mn–0.9Ca–0.6Y(AZXW9110)alloy is subjected to precompression and subsequent annealing(PCA)treatment for improving its bending formability,and the three-point bending properties of the as-extruded material and the precompressed and subsequently annealed(PCAed)material at room temperature are *** bending,microcracks formed in undissolved Al2Ca,Al2Y,and Al8Mn4Y particles propagate along the grain boundaries or twin boundaries and consequently form a macrocrack in the tension zones of the bending samples of both the ***,the bending formability of the PCAed material is 75%higher than that of the as-extruded material owing to the promoted twinning and slip behaviors in the *** as-extruded material has a strong normal direction(ND)texture and a weak transverse direction(TD)texture,and the ND-and TD-oriented grains are unfavorable for both{10–12}twinning and basal slip in the tension zone of the bending sample of this material,which eventually results in its low bending *** PCAed material has a strong extrusion direction(ED)texture,weak TD texture,and spread ND *** bending,{10–12}twins are fully formed in the ED-oriented grains,and this{10–12}twinning effectively accommodates the plastic strain in the tension *** addition,the activation of basal slip in the ND-oriented grains of the PCAed material is promoted owing to the spread ND texture of this ***,this material exhibits substantially superior bending formability because of the vigorous{10–12}twinning in its ED-oriented grains and promoted basal slip in its ND-oriented grains.

关键词： Magnesium Bending formability Twinning Texture

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Land cover changes and fragmentation in mountain neotropical ecosystems of Oaxaca, Mexico under community forest management

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journal of forestry Research 2019年第1期30卷 143-155页

作者： Rafael M~a Navarro Cerrillo Dennis j.Esteves Vieira Susana Ochoa-Gaona Bernardus H.j.de jong M~a del Mar Delgado Serrano Depto. Ingeniería forestal Laboratorio de SelviculturaDendrocronología y Cambio Climático.Dendrodat Lab-ERSAF Universidad de Córdoba Depto. de Engenharia florestal Faculdade de Engenharia Florestal Laboratório de Sensoriamento Remoto e Geotecnologia Universidade Federal de Mato Grosso Departamento de Ciencias de la Sustentabilidad El Colegio de la Frontera Sur-Unidad Campeche Depto. Economía Sociología y Política Agrarias Grupo de Evaluación y Restauración de Sistemas Agrícolas y Forestales-ERSAF Universidad de Córdoba

Changes in land cover have a direct impact on forest ecosystem goods and services. In this study, changes in land cover in Sierra de juarez–Oaxaca ecosystems were estimated using a consistent processing of Landsat images and OBIA methodology. Additionally, landscape analyses using fRAGSTAT were conducted. In 2014, Sierra de juarez–Oaxaca was covered by approximately 84% of forests, mainly pine-oak and cloud forests. After extensive deforestation until 2001, this trend was reversed and the forest cover surface area in 2014 was slightly higher than in 1979. The comparison of the landscape structure of the forested and agricultural lands suggests an increase in habitat heterogeneity. However, interspersion and juxtaposition indices, showing the patch shape by patch area and perimeter, were similar throughout the study period(1979–2014). Social and economic drivers can explain this situation: namely, community organization, forest enterprises, payment for ecosystem services programs, and changes of agricultural activity. Communities in the Sierra of Oaxaca have reforested degraded lands, created community forest enterprises, and preserved the forest under conservation schemes like those proposed by the Mexican payment for ecosystem services programs. However, their sustainable management faces internal challenges and has become highly dependent on political and institutional decisions beyond their control.

关键词： Tropical and temperate forests Social forestry Land uses segmentation OBIA fRAGSTAT

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Cool white light and tunable multicolor emission from Tb^(3+)/Dy^(3+)co-activated glasses under different excitations for WLEDs

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journal of Rare Earths 2024年第1期42卷 46-56,I0002页

作者： L.Vijayalakshmi K.Naveen Kumar jong Dae Baek Department of Automotive Engineering Yeungnam UniversityGyeongsanGyeongbuk38541Republic of Korea Department of Mechanical Engineering Yeungnam UniversityGyeongsan38541Republic of Korea

A set of co-doped(Tb^(3+)/Dy^(3+))lithium zinc borate(LZB)glasses were developed by melt *** structural evaluation was performed for synthesized glassy *** Dy^(3+)and Tb^(3+)individually doped glasses exhibit intense yellow and green luminescence bands at 575 nm(^(4)f_(9/2)→^(6)H_(13/2))and543 nm(^(5)D_(4)→^(7)f_(5)),*** sensitization effect of Dy^(3+)on Tb^(3+)was analyzed by increasing the Tb^(3+)content with respect to the optimum Dy^(3+)content(0.5 mol%)in Dy^(3+)/Tb^(3+).The spectral overlay of Dy^(3+)luminescence and Tb^(3+)absorption profiles,Dy^(3+)/Tb^(3+)PL spectra under different excitations 352,362,376,and 385 nm,shortening decay lifetimes of Dy^(3+)in Dy^(3+)/Tb^(3+)co-activated glasses,energy transfer(ET)parameters,chromaticity coordinates and their corresponding correlated temperatures all help to explain ET from Dy^(3+)to Tb^(3+).At 385 nm of Dy^(3+)excitation,the optimized co-activated(0.5Dy^(3+)+1.0Tb^(3+)):LZB glass displays cool white light *** non-radiative ET from Dy^(3+)to Tb^(3+)is dominated by electric dipole-dipole interaction and its ET efficiency was calculated to be 63%.At the same time,reverse ET from Tb^(3+)to Dy^(3+)was also *** shift in color coordinates from dominant yellow to greenish-yellow,green and white light emission suggests that Dy^(3+)/Tb^(3+)coactivated LZB glasses can be a potential candidate for UV converted multicolor and white light emitting devices.

关键词： Rare earths Photoluminescence Energy transfer Spectral overlap Decay lifetime Multicolor emitting LEDs

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Ballistic limit velocity of small caliber projectiles against SS400 steel plates:Live fire experiments and empirical models

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Defence Technology（防务技术） 2024年第11期41卷 22-34页

作者： jong-Hwan Kim Seungwon Baik jirui fu joon-Hyuk Park Mechanical&Systems Engineering Korea Military Academy574 Hwarang-roNowon-guSeoul17977South Korea Mechanical and Aerospace Engineering University of Central Florida4000 Central Florida BlvdOrlandoFL 32816United States

This study presents the ballistic limit velocity of small caliber projectiles against SS400 steel plate derived from live-fire ballistic experiments. four different small caliber projectiles were tested against SS400 steel plates of 9 mm, 10 mm, and 12 mm thicknesses. The ballistic limit velocity was calculated using two standard methods, MIL-STD-662f and NIj-STD-0101.06, and additionally using a support vector machine algorithm. The results show a linear relationship between the plate thickness and ballistic limit velocity. further, the relative penetration performance among five different small caliber projectiles was analyzed using the Penetration Performance Ratio(PPR) introduced in this study, which suggests the potential of PPR to predict the ballistic limit velocity of other untested materials and/or different projectiles.

关键词： Live fire ballistic experiment SS400 Ballistic limit velocity Small caliber projectile

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Influence of Bi addition on dynamic recrystallization and precipitation behaviors during hot extrusion of pure Mg

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journal of Materials Science & Technology 2020年第9期44卷 62-75页

作者： jongbin Go jong Un Lee Hui Yu Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu41566Republic of Korea School of Materials Science and Engineering Hebei University of TechnologyTianjin300130China

Low material cost and high extrudability for ensuring price competitiveness with Al alloys,as well as excellent mechanical properties,are essential for expanding the application range of Mg *** is a promising alloying element for developing extruded Mg alloys that satisfy such *** is inexpensive,exhibits a high solubility limit,and forms a thermally stable Mg3Bi2 phase,which improves the commercial viability and enables the high-speed extrusion of Mg–Bi *** this study,the effects of Bi addition on the dynamic recrystallization(DRX)and dynamic precipitation behaviors during hot extrusion of a pure Mg and the resultant microstructure and mechanical properties of the extruded materials were *** addition of 6 wt%and 9 wt%Bi to a pure Mg yielded numerous fine Mg3Bi2 precipitates during the early stage of hot ***,the area fraction of dynamic recrystallized(DRXed)grains decreased because of DRX-behavior suppression by the Zener pinning ***,the DRXed grain size was substantially reduced through the grain-boundary pinning *** size and number of undissolved Mg3Bi2 particles in the homogenized billets increased when the Bi content was increased,which resulted in increased DRX fractions owing to the enhanced levels of particle stimulated *** addition yielded considerable strength improvement of the extruded pure ***,the extruded Mg–Bi binary materials were less ductile than the extruded pure Mg *** lower ductility resulted from the cracking at twins formed in the coarse unDRXed grains of the Mg-6Bi material and the cracking at large undissolved Mg3Bi2 particles in the Mg-9Bi material.

关键词： Magnesium Bi addition Extrusion Recrystallization Precipitation

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Response of phenology- and yield-related traits of maize to elevated temperature in a temperate region

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The Crop journal 2017年第4期5卷 305-316页

作者： Dana Shim Kyu-jong Lee Byun-Woo Lee Department of Plant Science Seoul National University Seoul 151-921 Republic of Korea Research Institute for Agriculture and Life Sciences Seoul National University Seoul 151-921 Republic of Korea

Extreme high temperatures detrimental to maize production are projected to occur more frequently with future climate *** and yield-related traits were investigated under several levels of elevated temperature in two early-maturing hybrid cultivars:junda 6(grown in northeastern China)and Chalok 1(grown in South Korea).They were cultivated in plastic houses in Suwon,Korea(37.27°N,126.99°E)held at target temperatures of ambient(AT),AT+1.5°C,AT+3°C,and AT+5°C at one sowing date in 2013 and three different sowing dates in *** and reproductive growth durations showed variation depending on sowing date,experimental year,and *** duration tended to decrease,but not necessarily,with temperature elevation,but somewhat increased again above a certain *** temperature-dependent variation was greater during grain filling than in the vegetative period before *** temperature showed no significant effects on duration or peak dates of silking and anthesis,and thus on anthesis–silking *** yield tended to decrease with temperature elevation above ambient,showing a sharper linear decrease with mean growing season temperature increase in junda 6 than in Chalok *** decrease in kernel number accounted for a much greater contribution to the yield reductions due to temperature elevation than did the decrease in individual kernel weight in both *** harvestable kernel weight was not significantly affected by temperature elevation *** number showed a linear decrease with mean growth temperature from early ear formation to early grain-filling stage,with junda 6 showing a much severer decrease than Chalok *** number reduction due to temperature elevation was attributable more to the decrease in differentiated ovule number than to the decrease in kernel set in Chalok 1,but largely to the decrease of kernel set in junda 6.

关键词： Maize Elevated temperature Phenology Yield Yield-related traits

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An evaluation of a perfluoromethylcyclohexane(PMCH) permeation plug release vessel(PPRV) in a controlled turbulent environment

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International journal of Mining Science and Technology 2015年第2期25卷 243-251页

作者： jong Edmund C. Luxbacher Kray D. Department of Mining and Minerals Engineering Virginia Tech

The use of sulfur hexafiuoride （Sf6） as a tracer gas for analyzing underground mine ventilation systems has been practiced for over 30 years. As a result, the methods used to release, sample, and analyze Sf6 are well accepted. As the complexity and size of underground mine ventilation networks increase, the ability of a Sf6 to function as a convenient and rapid means of analysis diminishes. The utilization of multiple tracer gases can mitigate this by removing the need to purge the background presence of a tracer before conducting another release and allowing for a more comprehensive evaluation using multi-zone tech- niques. Recent studies have identified perfluoromethylcyclohexane （PMCH） as a possible supplement for Sf6 in underground mine ventilation tracer studies. However, the deployment of PMCH remains a challenge because of this compounds physical properties. This paper evaluates a PMCH permeation plug release vessel （PPRV） under controlled turbulent conditions. The details of the experimental parameters used in the evaluation as well as a discussion regarding the performance of the PPRV are included.

关键词： Tracer gas Underground mines Mine ventilation Perfluoromethylcyclohexane

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Aberrant expression of enzymes regulating m^6A mRNA methylation: implication in cancer

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Cancer Biology & Medicine 2018年第4期15卷 323-334页

作者： Natalia Pinello Stephanie Sun justin jong-Leong Wong Epigenetics and RNA Biology Program Centenary Institute The University of Sydney Sydney Medical School The University of Sydney

N^6-methyladenosine(m^6 A) is an essential RNA modification that regulates key cellular processes, including stem cell renewal,cellular differentiation, and response to DNA damage. Unsurprisingly, aberrant m^6 A methylation has been implicated in the development and maintenance of diverse human cancers. Altered m^6 A levels affect RNA processing, mRNA degradation, and translation of mRNAs into proteins, thereby disrupting gene expression regulation and promoting tumorigenesis. Recent studies have reported that the abnormal expression of m^6 A regulatory enzymes affects m^6 A abundance and consequently dysregulates the expression of tumor suppressor genes and oncogenes, including MYC, SOCS2, ADAM19, and PTEN. In this review, we discuss the specific roles of m^6 A missing space "writers", "erasers", and "readers" in normal physiology and how their altered expression promotes tumorigenesis. We also describe the potential of exploiting the aberrant expression of these enzymes for cancer diagnosis, prognosis, and the development of novel therapies.

关键词： RNA modification N^6-methyladenosine (m^6A) cancer tumor suppressor oncogene

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