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Journal of Materiomics 2024年第3期10卷 632-642页

作者： Su-Hwan Go Seok-Jung Park Seung-Hyun.kim Seok-June Chae Eun-Ji kim Geun-Su Lee Sahn nahm Department of Materials Science and Engineering Korea UniversitySeoul02841Republic of Korea

0.96(K_(0.5)na_(0.5-z)Li_(z))(nb_(0.92)Sb_(0.08))O_(3)-0.04(Ca_(0.5)Sr_(0.5))ZrO_(3)[(Kn_(0.5-z)L_(z))nS-CSZ]piezoceramics(0≤z≤0.04)were aligned in the[001]orientation using 3%(in mole)nanbO_(3)templates with a large Lotgering factor(>97%).Their crystal structures transformed from the orthorhombic-pseudocubic(O-P)structure to the orthorhombic-tetragonal-pseudocubic(O-T-P)structure with an increasing *** P structure was interpreted as a rhombohedral R3m *** piezoelectricity of the compositions increased after[001]-texturing,and the enhancement was proportional to the O phase *** composition(z=0.03)exhibited the highest piezoelectric constant(d_(33);670 pC/n)and electromechanical coupling factor(k_(p);0.56).Piezoelectric energy harvesters were produced using the untextured and textured samples(z=0.03).The textured harvester delivered a large power density of 26.6 mW/mm^(3),which was larger than that of the untextured harvester owing to the enhanced kp and d_(33)×g_(33) of the textured piezoceramic.A multilayer actuator was produced using the textured sample(z=0.03),and it exhibited a large acceleration(44.2 G)and displacement(±3,730 mm)at±25 ***,the[001]-textured(Kn_(0.47)L_(0.03))nS-CSZ piezoceramic is suitable for piezoelectric energy harvesters and actuators.

关键词： Knn-Based piezoceramic Lead-free Energy harvester Actuator Reactive template grain growth

n,P co-doped 3D porous carbon with self-assembled morphological control via template-free method for potassiumion battery anodes

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Rare Metals 2024年第9期43卷 4243-4252页

作者： Jeehoon Yu Dae Kyom kim Hong Geun Oh Seung-Keun Park Youngjae Yoo Department of Advanced Materials Engineering Chung-Ang UniversityAnseong-si 17546Republic of Korea

The larger ionic radius of potassium ions than that of lithium ions significantly limits the accomplishment of rapid diffusion kinetics in graphite electrodes for potassium-ion batteries(PIBs),resulting in comparatively poor rate performance and cycle ***,we report a high-rate performance and cycling stability amorphous carbon electrode achieved through nitrogen and phosphorous *** as-prepared n,P co-doped carbon electrodes have distinct 3D structures with large surface areas,hierarchical pore architectures,and increased interlayer spaces resulting from the direct pyrolysis of supramolecular self-assembled aggregates without *** obtained electrode n3P1 exhibits a reversible specific capacity of 258 m Ah·g^(-1)at a current density of 0.1A·g^(-1)and a good long-term cycle performance(96.1%capacity retention after 800 cycles at 0.5 A·g^(-1)).Kinetic investigations show that the n3P1 electrode with the welldeveloped porous structure and large number of surface defects exhibits capacitive-driven behavior at all scan rates,which may be attributed by n and P ***-situ transmission electron microscopy analyses in the fully discharged and charged states demonstrate structural stability and reversibility owing to the expanded interlayer *** suggested synthesis approach is simple and effective for producing heteroatom-doped carbon materials for PIBs and other advanced electrochemical energy storage materials.

关键词： Amorphous carbons 3D porous structures nitrogen and phosphorous co-doping Potassium-ion batteries

Predicting moisture condensation risk on the radiant cooling floor of an office using integration of a genetic algorithm-back-propagation neural network with sensitivity analysis

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Energy and Built Environment 2024年第1期5卷 110-129页

作者： Meng Su Jiying Liu Moon Keun.kim Xiaozhou Wu School of Thermal Engineering Shandong Jianzhu UniversityJinan 250101China Department of Civil Engineering and Energy Technology Oslo Metropolitan UniversityOslo N-0130Norway School of Civil Engineering Dalian University of TechnologyDalianChina

Pre-dehumidification time(τ_(pre))and pre-dehumidification energy consumption(E_(pre))play important roles in preventing the condensation of moisture on the floors of rooms that use a radiant floor cooling(RFC)***,there are few theoretical or experimental studies that focus on these two important *** this study,an artificial neural network(Ann)was used to predict condensation risk for the integration of RFC systems with mixed ventilation(MV),stratum ventilation(SV),and displacement ventilation(DV)systems.A genetic algorithm-back-propagation(GA-BP)neural network model was established to predict τ_(pre) and E_(pre).Both training data and validation data were obtained from tests in a computational fluid dynamics(CFD)*** results show that the established GA-BP model can predict τ_(pre) and E_(pre) *** coefficient of determination(R^(2))of τ_(pre) and of E_(pre) were,respectively,0.973 and *** an RFC system integrated with an MV,SV,or DV system,the lowest values of τ_(pre) and E_(pre) were with the DV system,23.1 s and 0.237 kWh,respectively,for a 67.5 m^(3) ***,the best pre-dehumidification effect was with integration of the DV and RFC *** study showed that an Ann-based method can be used for predictive control for condensation prevention in RFC *** also provides a novel and effective method by which to assess the pre-dehumidification control of radiant floor surfaces.

关键词： Condensation prevention Radiant floor cooling Ventilation system genetic algorithm BP neural network

On von neumann Regularity of Commutators

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Algebra Colloquium 2024年第2期31卷 181-198页

作者： nam Kyun.kim Tai Keun Kwak Yang Lee Sung Ju Ryu nanqing Ding School of Basic Sciences Hanbat National UniversityDaejeon 34158Korea Department of Data Science Daejin UniversityPocheon 11159Korea Department of Mathematics Yanbian UniversityYanjiJilin 133002China Institute for Applied Mathematics and Optics Hanbat National University Daejeon 34158Korea Department of Mathematics Pusan National UniversityBusan 46241Korea 不详

We study the structure of rings which satisfy the von neumann regularity of commutators,and call a ring R C-regularif ab-ba ∈(ab-ba)R(ab-ba)for all a,b in *** a C-regular ring R,we prove J(R[X])=n^(*)(R[X])=n^(*)(R)[X]=W(R)[X]■Z(R[X]),where J(A),n^(*)(A),W(A),Z(A)are the Jacobson radical,upper nilradical,Wedderburn radical,and center of a given ring A,respectively,and A[X]denotes the polynomial ring with a set X of commuting indeterminates over A;we also prove that R is semiprime if and only if the right(left)singular ideal of R is *** provide methods to construct C-regular rings which are neither commutative nor von neumann regular,from any given ***,for a C-regular ring R,the following are proved to be equivalent:(i)R is Abelian;(ii)every prime factor ring of R is a duo domain;(ii)R is quasi-duo;and(iv)R/W(R)is reduced.

关键词： C-regular ring commutator regular ring commutative ring radical singular ideal

Active and passive modulation of solar light transmittance in a uniquely multifunctional dual-band single molecule for smart window applications

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Journal of Energy Chemistry 2024年第1期88卷 293-305,I0007页

作者： Pooja V.Chavan Pramod V.Rathod Joohyung Lee Sergei V.Kostjuk hern.kim Department of Energy Science and Technology Environmental Waste Recycle InstituteMyongji UniversityYonginGyeonggi-do 17058Republic of Korea Department of Chemical Engineering Myongji UniversityYonginGyeonggi-do 17058Republic of Korea Research Institute for Physical Chemical Problems of the Belarusian State University MinskBelarus

Functional materials may change color by heat and electricity separately or simultaneously in smart *** materials have not only demonstrated remarkable potential in the modulation of solar radiation but are also leading to the development of indoor environments that are more comfortable and conducive to improving individuals'quality of ***,dual-responsive materials have not received ample research attention due to economic and technological *** a consequence,the broader utilization of smart windows faces *** address this new generational multistimulus responsive chromic materials,our group has adopted a developmental strategy to create a poly(nIPAM)n-HV as a switchable material by anchoring active viologen(HV)onto a phase-changing poly(nIPAM)n-based smart material for better utility and *** constructed smart windows facilitate individualistic reversible switching,from a highly transparent state to an opaque state(thermochromic)and a red state(electrochromic),as well as facilitate a simultaneous dual-stimuli response reversible switching from a clear transparent state to a fully opaque(thermochromic)and orange(electrochromic)*** privacy can be attained in smart windows designed for exclusive settings by achieving zero *** unique chromic mode operates independently and modulates visible and near-infrared(nIR)light in a distinct ***,these smart windows with thermal and electric dual-stimuli responsiveness demonstrate remarkable heat regulation capabilities,rendering them highly attractive for applications in building facades,energy harvesting,privacy protection,and color display.

关键词： Smart windows Thermochromism Electrochromism Energy saving Dual-responsive material

The Effects of Accumulated Short Bouts of Mobile-Based Physical Activity Programs on Depression,Perceived Stress,and negative Affectivity among College Students in South Korea:Quasi-Experimental Study

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International Journal of Mental health Promotion 2024年第7期26卷 569-578页

作者： Ye Hoon Lee Yonghyun Park Hyungsook kim Division of Global Sport Industry Hankuk University of Foreign StudiesGyeonggi-doRepublic of Korea Department of Data Science Hanyang UniversitySeoulRepublic of Korea HY Digital healthcare Center Hanyang UniversitySeoulRepublic of Korea

Regular physical activity(PA)is known to enhance multifaceted health beneﬁts,including both physical and mental ***,traditional in-person physical activity programs have drawbacks,including time constraints for busy *** evidence suggests positive impacts on mental health through mobile-based physical activity,effects of accumulated short bouts of physical activity using mobile devices are ***,this study aims to investigate these effects,focusing on depression,perceived stress,and negative affectivity among South Korean college ***-six healthy college students were divided into the accumulated group(n=23,female=47.8%)and control group(n=23,female=47.6%).The accumulated group engaged in mobile-based physical activity,following guidelines to accumulate a minimum of two times per day and three times a *** were divided into short bouts,ensuing each bout lasted at least 10 *** control group did not engage in any speciﬁc physical *** data analysis involved comparing the scores of the intervention and control groups using several statistical techniques,such as independent sample t-test,paired sample t-tests,and 2(time)×2(group)repeated measures analysis of *** demographic characteristics at the pre-test showed no statistically signiﬁcant differences between the *** accumulated group had signiﬁcant decreases in depression(t_(40)=2.59,p=0.013,Cohen’s D=0.84)and perceived stress(t_(40)=2.06,p=0.046,Cohen’s D=0.56)from the pre-to *** control group exhibited no statistically signiﬁcant differences in any ***,there were signiﬁcant effects of time on depression scores(F1,36=4.77,p=0.036,η_(p)^(2)=0.12)while signiﬁcant interaction effects were also observed for depression(F_(1,36)=6.59,p=0.015,η_(p)^(2)=0.16).This study offers informative insights into the potential advantages of mobile-based physical activity programs with accumulated periods for enhancing mental health

关键词： Depressive symptoms mental health mobile intervention short term exercise stress

Effective parameters on polydimethylsiloxane/graphene composite-based triboelectric nanogenerator performance

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International Journal of Smart and nano Materials 2024年第2期15卷 365-386页

作者： Fattaneh Salemi Fathallah Karimzadeh Mohammad-Hasan Abbasi Fatemeh Moradi Duc Hoa Pham Jaehwan.kim Department of Materials Engineering Isfahan University of Technology(IUT)IsfahanIran CRC for nanocellulose Future Composites Department of Mechanical EngineeringInha UniversityIncheonRepublic of Korea

This paper systematically investigates the effective parameter ontheperformanceof polydimethylsiloxane/graphene(PDMS@Gr)-based triboelectric nanogenerators(TEnGs)as well as their ***@Gr films containing 0,0.05,0.5,1,and 1.5 wt.%graphene are synthesized,and their sur-face characteristics,mechanical behavior,and electrical prop-erties are *** contact-separation mode TEnGs are fabricated,and their performance is *** results demonstrate that the surface roughness and sur-face charge density are the most critical parameters for the performance of PDMS@Gr-based TEnGs compared to the elec-trical and mechanical properties of the friction *** PDMS@Gr-based TEnG with 1 wt.%graphene shows the high-est power output of 2.6 W/m?at an optimized working con-dition(5 Hz and 15 n).It also exhibits stable power output until 15,oo0 working cycles and displays battery-free applica-tions by powering a light-emitting diode(LED)array,a calculator,a digital watch,and a digital thermometer.

关键词： Energy harvester triboelectric nanogenerator graphene polydimethylsiloxane composite

Computational study of flow separation in truncated ideal contour nozzles under high-altitude conditions

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International Journal of Fluid Engineering

International Journal of Fluid Engineering 2024年第1期 21-30页

作者： Ijas Muhammed V V Shamsia Banu n Abhilash Suryan Vincent Lijo David Simurda heuy Dong kim College of Engineering Trivandrum Government Engineering College Thrissur Faculty of Mechanical Engineering Technical University of Liberec Andong national University

Flow separation in rocket nozzles has been studied mostly under sea-level conditions, which fail to take into account changes in ambient density and ambient pressure during the flight of a rocket. In the present study, numerical analysis is conducted of flow characteristics within a truncated ideal contour(TIC) nozzle to investigate the influence of ambient density and pressure on flow separation. Six different altitudes from a typical flight are considered, from a very low altitude to a high altitude. The flow is analyzed by varying the nozzle pressure ratios corresponding to these altitudes. Both cold flow and hot flow simulations are conducted. The locations of separation positions at various altitude conditions are accurately captured and are found to be in good agreement with experimental results. The results of the study establish that for a given nozzle pressure ratio, the flow separation point is shifted upstream with increasing altitude. This clearly points to a dependence of separation position on the altitude of operation for TIC rocket nozzles.

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Malignant triton tumor in the abdominal wall:A case report

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World Journal of Clinical Cases 2024年第8期12卷 1467-1473页

作者： Ho Jik Yang Donghyun.kim Won Suk Lee Sang-Ha Oh Department of Plastic and Reconstructive Surgery Chungnam National University Sejong HospitalSejong 30099South Korea Department of Plastic and Reconstructive Surgery Chungnam National University HospitalDaejeon 35015South Korea Department of Emergency Eulji University HospitalDaejeon 35233South Korea Department of Plastic and Reconstructive Surgery Chungnam National University College of MedicineDaejeon 35015South Korea

BACKGROUnD Malignant triton tumors(MTTs)comprise a subgroup of malignant peripheral nerve sheath tumors(MPnSTs)that exhibits rhabdomyosarcomatous differen-tiation and follow an aggressive *** are primarily located along peripheral *** of MTTs in the abdominal wall have not been *** has a poorer prognosis than classic MPnSTs,and accurate diagnosis necessitates a keen understanding of the clinical history and knowledge of its differential diagnosis *** for MTTs mirrors that for MPnSTs and is predominantly *** SUMMARY A 49-year-old woman presented with a subcutaneous mass in her lower abdo-minal wall and a pre-existing surgical scar that had grown slowly over 3-4 months before the *** had previously undergone radical hysterectomy and concurrent chemo-radiotherapy for cervical cancer approximately 5 years prior to the *** computed tomography(CT)showed a 1.3 cm midline mass in the lower abdomen with infiltration into the rectus abdominis *** was no sign of metastasis(T1n0M0).An incisional biopsy identified sporadic MTT of the lower abdomen.A comprehensive surgical excision with a 3 cm margin inclusive of the peritoneum was ***-quently,the general surgeon utilized an approach akin to the open peritoneal onlay mesh *** patient underwent additional treatment with an excision shaped as a mini-abdominoplasty for the skin *** complications arose,and annual follow-up CTs did not show signs of recurrence or *** An abdominal MTT was efficaciously treated with extensive excision and abdominal wall reconstruction,eliminating the need for postoperative radiotherapy.

关键词： Malignant triton tumor Abdominal wall Surgical excision Reconstruction Case report

Three-dimensional analysis of age and sex differences in femoral head asphericity in asymptomatic hips in the United States

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World Journal of Orthopedics 2024年第8期15卷 754-763页

作者： Mahad M Hassan Aliya G Feroe Brenton W Douglass Andrew E Jimenez Benjamin Kuhns Charles F Mitchell Robert L Parisien Daniel A Maranho Eduardo n novais Young-Jo kim Ata M Kiapour Department of Orthopedic Surgery University of MinnesotaMinneapolisMN 55454United States Department of Orthopedic Surgery TRIA Orthopaedic CenterBloomingtonMN 55122United States Department of Orthopedic Surgery Boston Children’s HospitalBostonMA 02115United States Department of Orthopedic Surgery Mayo ClinicRochesterMN 55901United States Department of Orthopaedics and Rehabilitation Yale School of MedicineNew HavenCT 06510United States Department of Orthopedic Surgery American Hip Institute Research FoundationDes PlainesIL 60018United States Department of Orthopedic Surgery Mount SinaiNew YorkNY 10029United States Department of Biomechanics Medicineand Rehabilitation of the Locomotor SystemRibeirao Preto Medical SchoolUniversity of São PauloRibeirao Preto 14048-900São PauloBrazil

BACKGROUnD The sphericity of the femoral head is a metric used to evaluate hip pathologies and is associated with the development of osteoarthritis and femoral-acetabular *** To analyze the three-dimensional asphericity of the femoral head of asymptomatic pediatric *** hypothesized that femoral head asphericity will vary significantly between male and female pediatric hips and increase with age in both *** Computed tomography scans were obtained on 158 children and adolescents from a single institution in the United States(8-18 years;50%male)without hip *** femoral measurements including the femoral head diameter,femoral head volume,residual volume,asphericity index,and local diameter difference were used to evaluate femoral head *** In both sexes,the residual volume increased by age(Pnificantly smaller femoral head size in older ages(>13 years)in females,there were no sex-differences in residual volume and aspherity *** were no age-related changes in mean diameter difference in both sexes(P=0.07)with no significant sex-differences across different age groups(P=0.06).In contrast,there were significant increases in local aspherity(maximum diameter difference)across whole surface of the femoral head and all quadrants except the inferior regions in males(P=0.03).There were no sex-differences in maximum diameter difference at any regions and age group(P>0.05).Increased alpha angle was only correlated to increased mean diameter difference across overall surface of the femoral head(P=0.024).COnCLUSIOn There is a substantial localized asphericity in asymptomatic hips which increases with age *** 2D measured alpha angle can capture overall asphericity of the femoral head,it may not be sensitive enough to represent regional asphericity patterns.

关键词： Hip Femoral head Sphericity Skeletal growth Sex differences