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Journal of Materials Science & Technology 2016年第7期32卷 660-670页

作者： S.y. park W.J. Kim Department of Materials Science and Engineering Hongik University 72-1 Sangsu-dong Mapo-gu Seoul 121-791 Republic of Korea Advanced Fusion Process R&D Group Korea Institute of Industrial Technology 994-32 Dongchun-dong Yeonsu-gu Incheon 406-130 Republic of Korea

The deformation mechanisms and processing maps of the as-cast Al-Zn-Mg-Cu （？0？5） aluminum （AI） alloy were studied and compared with those of the homogenized 7075 Al alloy in the temperature range of 573-723 K and in the strain rate range of 10 3-10 s-1 to explore a possibility for directly using the as- cast 7075 Al alloy as a billet for hot working. The as-cast and homogenized 7075 A1 alloys had similar grain sizes and showed similar high-temperature deformation behaviors. The as-cast 7075 Al alloy, however, exhibited higher power efficiencies and smaller unstable flow regions compared to the homogenized 7075 AI alloy because of the presence of secondary phases （MgZn2） segregated at the dendritic interfaces in the as-cast microstructure, which were formed during non-equilibrium solidification. These segregated phases provided nucleation sites for dynamic recovery or continuous dynamic recrystallization, and as a result a fine and more homogeneous （sub）grain structure could be obtained from the as-cast micro- structure compared to the homogenized microstructure. The current work suggested the possibility and advantage of using as-cast microstructures for hot working of aluminum alloys with high content of solutes.

关键词： Al-based alloysProcessing maphot compressionAs-cast microstructureSegregationRecrystallization

Adaptive Functional Projective Lag Synchronization of a hyperchaotic Rossler System

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Chinese Physics Letters 2009年第9期26卷 69-72页

作者： Tae h. Lee Ju h. park Nonlinear Dynamics Group Department of Electrical Engineering Yeungnam University 214-1 Dae-Dong Kyongsan 712-749 Republic of Korea

We explain the functional projective lag synchronization of a hyperchaotic Rossler system with four unknown parameters, where the output of the master system lags behind the output of the slave system proportionally. Based on Lyapunov stability theory, an active control method and adaptive control law are employed to make the states of two hyperchaotic Rossler systems asymptotically synchronized. Finally, some numerical examples are provided to show the effectiveness of our results.

关键词： No English Keyword

home Range Size and Overlap of the Small Nocturnal Schlegel’s Japanese Gecko (Gekko japonicus), Introduced into a City park in Korea

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Asian herpetological Research 2019年第4期10卷 261-269页

作者： Il-Kook park Dae-In KIM Jonathan JFONG Daesik park Department of Biology Kangwon National UniversityChuncheonKangwon 24341South Korea Science Unit Lingnan UniversityTuen MunNew TerritoriesHong KongChina Division of Science Education Kangwon National UniversityChuncheonKangwon 24341South Korea

Studying the home range of an organism is important in understanding its ecology. Due to being cryptic, few studies have been conducted on the home range studies of small, nocturnal geckos. We conducted radio-tracking surveys for 23 individuals to estimate the home range size and home range overlap of the Schlegel’s Japanese gecko(Gekko japonicus) previously introduced into a suburban city park. Individuals were commonly found in artificial structures(buildings and accessory structures) and on nearby natural trees. Daily moved distance was positively correlated with home range size. Minimum convex polygon(MCP) home range was 97.8 m^2 for females and 99.5 m^2 for males, on average. Gekko japonicus moved farther daily distances and used wider MCP and Kernel 95 home ranges in breeding season compared to non-breeding season, while the size of Kernel 50 home range did not differ between seasons. Both daily moved distance and home range size were not significantly different between sexes. In the breeding season, MCP and Kernel 50 home ranges of each gecko overlapped with 32.4% and 13.8% of remaining geckos, respectively. Our results not only show that 1) G. japonicus uses both artificial structures and adjacent natural trees as microhabitat, but also suggest that 2) G. japonicus is non-territorial, but has a core habitat that is shared with few other individuals, and 3) the reproductive system of G. japonicus is polygamous.

关键词： radio telemetry invasive species territory lizard Korea

Unassisted overall water splitting with a solar-to-hydrogen efficiency of over 10% by coupled lead halide perovskite photoelectrodes

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Carbon Energy 2023年第1期5卷 134-143页

作者： Ryan Rhee Tae G.Kim Gyu y.Jang Gwangmin Bae Jung h.Lee Sunje Lee Sungsoon Kim Seokwoo Jeon Jong h.park Department of Chemical and Biomolecular Engineering Yonsei UniversitySeoulRepublic of Korea Department of Materials Science and Engineering KAIST Institute for The Nanocentury(KINC)Korea Advanced Institute of Science and Technology(KAIST)DaejeonRepublic of Korea

hydrogen is a promising future sustainable fuel candidate with boundless *** into photoelectrochemical(PEC)water splitting based on a lead halide perovskite(LhP)has progressed significantly with the aim of more efficient solar hydrogen ***,we unite a well-known photo-absorbing LhP with cost-effective water-splitting catalysts,and we introduce two types of monolithic LhP-based PEC devices that act as a photocathode and a photoanode for the hydrogen evolution reaction and oxygen evolution reaction,leading to efficient unbiased overall water *** the integration of these two monolithic LhP-based photoelectrodes,an unbiased solar-to-hydrogen conversion efficiency of 10.64%and a photocurrent density of 8.65 mA cm^(−2) are achieved.

关键词： perovskite photoelectrochemical cell photoelectrode unassisted

Effects of thermal boundary conditions on the joule heating of electrolyte in a microchannel

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Journal of hydrodynamics 2016年第5期28卷 850-862页

作者： M. y. ABDOLLAhZADEh JAMALABADI J. h. park M. M. RAShIDI J. M. ChEN Department of Ship Engineering Chabahar Maritime University Chabahar Iran Department of Aerospace and System Engineering Gyeongsang National University Jinju Korea . Engineering Faculty of Bu-Ali Sina University Hamedan Iran Department of Mechanical and Nuclear Engineering Kansas State University Manhattan USA

Joule heating effects on a slit microcharmel filled with electrolytes are comprehensively investigated with emphasis on the thermal boundary conditions. An accurate analytical expression is proposed for the electrical field and the temperature distributions due to Joule heating are numerically obtained from the energy balance equation. The results show that a thermal design based on the average electric potential difference between electrodes can cause severe underestimation of Joule heating. In addition, the parame- tric study of thermal boundary conditions gives us an insight into the best cooling scenario for microfluidic devices. Other significant thermal characteristics, including Nusselt number, thermophoretic force, and entropy generation, are discussed as well. This study will provide useful information for the optimization of a bioMEMS device in relation to the thermal aspect.

关键词： microchannel electrolyte joule heating Nusselt number thermophoretic force entropy generation optimized thermaldesign

Redox Charge Transfer Kinetics and Reversibility of VO_(2) in Aqueous and Non-Aqueous Electrolytes of Na-Ion Storage

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Energy & Environmental Materials 2022年第4期5卷 1222-1228页

作者： Sul Ki park Kang ho Shin Puritut Nakhanivej harpalsinh h.Rana ho Seok park School of Chemical Engineering College of EngineeringSungkyunkwan University2066Seobu-roJangan-guSuwon-si Gyeonggi-do 440-746Republic of Korea Department of Engineering University of CambridgeCambridge CB30FSUK Department of health Sciences and Technology Samsung Advanced Institute for Health Sciences and Technology(SAIHST)Sungkyunkwan University2066SeoburoJangan-guSuwon 440-746South Korea SKKU Advanced Institute of Nano Technology(SAINT) Sungkyunkwan University2066SeoburoJangan-guSuwon 440-746South Korea

The deep understanding about the electrochemical behavior of the nanostructured electrode in electrolytes provides crucial insights for the rational design of electrode for sodium(Na)-ion storage system(NIS).here,we report redox charge transfer kinetics and reversibility of VO_(2)(B) nanorod electrodes in both aqueous and organic electrolytes for *** assynthesized VO_(2)(B) nanorods show the reversible redox reaction with the higher specific and rate capacitances at high current density in aqueous electrolytes than in organic ***-dependent impedance measurements demonstrate the more facile interfacial charge transfer of Na ions into VO_(2)(B) nanorods in aqueous *** reversible evolution in oxidation state and chemical composition of VO_(2)(B) nanorods is observed in aqueous electrolytes,as confirmed by ex situ XRD and ex situ X-ray photoelectron spectroscopy *** by the facile and reversible pseudocapacitive feature,the electrochemical performances of VO_(2)(B) nanorods are further improved by constructing the hierarchical structure of the reduced graphene oxide-VO_(2) composite for aqueous Na+ion storage.

关键词： aqueous electrolyte energy storage mechanism hierarchical structure nanorod sodium ion storage

Influence of Carrier Gas on Analysis of MgO Powders by Laser Ablation Inductively Coupled Plasma Mass Spectrometry

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Journal of Materials Science & Technology 2009年第3期25卷 333-335页

作者： J.S. Lee y.S. Lee C.J. park h.S. Lee D.S. Lee Department of Chemistry Yonsei University Material Analysis Team Korea Testing Laboratory Korea Research Institute of Standards and Science School of Material Science and Engineering Pusan National Univirsity

Laser ablation inductively coupled plasma mass spectrometry （LA-ICP-MS） has been widely adopted for the direct multi-elemental analysis with high sensitivity. Especially analysis of fine ceramics by LA-ICP-MS without time-consuming sample decomposition process has been one of the most expecting application field. Small additive elements in MgO powders were analyzed by LA-ICP-MS. For precise and accurate analysis influence of carrier gas （Ar or he） was presented by the signal intensities of ICP-MS, relative standard deviation of signal intensities and ablated particle size distribution. Ablated particles were collected and analyzed by scanning electron microscopy （SEM） to investigate the particle size distribution, and the ablated sample surface was examined by camscope. In he gas atmosphere, the signal was more stable than in Ar gas atmosphere. The signal intensity was higher in Ar than in he. Examination of ablated particles and sample surface reveals that more particles were generated in Ar atmosphere and the distribution of particle size was larger.

关键词： Laser ablation MgO powders Carrier gas ICP-MS

miR-21, miR-221 and miR-222 expression and prostate cancer recurrence among obese and non-obese cases

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Asian Journal of Andrology 2013年第2期15卷 226-230,I0007页

作者： Ernest K Amankwah Evelyn Anegbe hyun park Julio Pow-Sang Ardeshir hakam Jong y park Department of Cancer Epidemiology H. Lee Moffitt Cancer Center Tampa FL 33612 USA Department of G U Oncology H. Lee Moffitt Cancer Center Tampa FL 33612 USA Department of Anatomic Pathology H. Lee Moffitt Cancer Center Tampa FL 33612 USA

Recent evidence shows that certain microRNAs （miRNAs） play a role in both obesity and prostate cancer recurrence, but the association between the expression of these miRNAs and obesity in prostate cancer recurrence is unknown. In this study, we examined the effect of the interaction between obesity and miR-21, miR-221 or miR-222 expression on prostate cancer recurrence among 28 recurrent and 37 non-recurrent prostate cancer cases, miRNA expression was determined using quantitative real-time polymerase chain reaction. Cox proportional hazard models adjusting for age at diagnosis, clinical stage and Gleason score were used to estimate hazard ratios （hR） and 95% confidence intervals （95% CI） for recurrence free survival. A significantly （P=0.014） higher proportion of recurrent cases （78,6%） than non-recurrent cases （48.6%） had a low expression of miR-21 and the difference was more prominent in obese than non-obese patients. Multivariate analysis showed that the expression of miR-21 was an independent risk factor for recurrence in obese （hR=6.15, 95% CI= 1.04-36.48, P=-0.045）, but not in non-obese （hR= 1.28, 95% C1=0.30-5.49, P=0.74） cases. A significant association with recurrence was not observed for the expression of miR-221 and miR-222. In summary, our findings show that miR-21 is associated with prostate cancer recurrence after radical prostatectomy and suggest that the differential expression of miR-21 is more prominent in obese than in non-obese cases. Future larger studies are warranted to confirm these initial findings and to elucidate the mechanisms involved.

关键词： miR-21 miR-221 miR-222 miRNA obesity prostate carcinoma recurrence

A hybrid Joining Technology for Aluminum/Zinc Coated Steels in Vehicles

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Journal of Materials Science & Technology 2010年第9期26卷 858-864页

作者： C.y.Choi D.C.Kim D.G.Nam y.D.Kim y.D.park School of Materials Science and Engineering Pusan National UniversityBusan Advanced Welding & Joining R&D Division Institute of Industrial Technology Incheon Dongnam Technology Service Division Korea Institute of Industrial TechnologyBusan Department of Advanced Materials Engineering Dong-Eui UniversityBusan

Currently,in the automotive industry,joining of the aluminum alloys with the steel is a crucial problem to be *** joining techniques including resistance spot and gas metal arc welding are not acceptable for those applications due to a number of metallurgical *** investigation was carried out to develop the hybrid joining process combining the resistance spot welding and *** this study,an attempt was made to apply hybrid process to the joining of dissimilar sheet metals,Al-Mg-Si（6000 series） alloy and low carbon steel *** process（resistance spot weld/brazing） using filler metal was found to be effective to overcome the incompatibility between aluminum alloy and *** hybrid joining process of Al alloy sheet and steel sheet did not produce acceptable bond strength,it was proved to have reasonable interfacial bond layer if the optimal process condition was applied.

关键词： hybrid joining Aluminum alloy Steel Resistance welding Brazing

Optimal design of V-type ultrasonic motor

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Journal of Central South University 2010年第6期17卷 1247-1250页

作者： JEONG S S park C h park T G School of Mechatronics Changwon National UniversityChangwon 641773Korea

V-type ultrasonic linear motor fabricated using a simple punching technique was proposed to utilize as an actuator of small precision *** stator of the motor is composed of a thin elastic body and four ceramics attached to the upper and bottom areas of the *** ceramics have each direction of *** two harmonic voltages with a 90° phase difference are applied to the ceramics,symmetric and anti-symmetric displacements will generate at the tip to produce an elliptical motion.A finite element analysis(ATILA) was conducted to simulate the motion pattern for the contact tip of the *** develop a model that generates the maximum displacement at contact tip,the FEM program was used for various *** addition,an optimal model was chosen by considering the magnitude and shape of the displacement according to changes in *** maximum elliptical displacement is shown by W2L11 model,which has a ratio of ceramic width to length of 1:***,the displacement of the contact tip is reduced by the bucking phenomenon if the ratio is larger than 1:6.

关键词： ultrasonic motor piezo-actuator finite element method optimal design elliptical motion