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941.
Analysis of continuous process of motor learning gives a lot of useful knowledge for the recovery of human motion activities, and functional adaptability in new environment. This paper proposes a valuation index for degree of proficiency, and shows results of motor skill analysis for several arm reaching tasks. The motor skills were evaluated by using the reproducibility of muscle activation patterns, which were represented by using the variance value of the Electromyographic (EMG) signal patterns, and the motion accuracy. We confirm that the reproducibility is high when the motion accuracy is high, and the various skill acquisition processes exist due to individual difference. We conclude that, the reproducibility is one of the important indices for evaluating the degree of proficiency. 相似文献
942.
Haeleen Hong Yei Hwan Jung Ju Seung Lee Chanho Jeong Jong Uk Kim Sori Lee Hyewon Ryu Heyn Kim Zhenqiang Ma Tae‐il Kim 《Advanced functional materials》2019,29(37)
Owing to the growing demand for highly integrated electronics, anisotropic heat dissipation of thermal management material is a challenging and promising technique. Moreover, to satisfy the needs for advancing flexible and stretchable electronic devices, maintaining high thermal conductivity during the deformation of electronic materials is at issue. Presented here is an effective assembly technique to realize a continuous array of boron nitride (BN) nanosheets on tetrahedral structures, creating 3D thermal paths for anisotropic dissipation integrated with deformable electronics. The tetrahedral structures, with a fancy wavy shaped cross‐section, guarantee flexibility and stretchability, without the degradation of thermal conductivity during the deformation of the composite film. The structured BN layer in the composites induces a high thermal conductivity of 1.15 W m?1 K?1 in the through‐plane and 11.05 W m?1 K?1 in the in‐plane direction at the low BN fraction of 16 wt%, which represent 145% and 83% increases over the randomly mixing method, respectively. Furthermore, this structured BN composite maintains thermal dissipation property with 50% strain of the original length of composite. Various electronic device demonstrations provide exceptional heat dissipation capabilities, including thin film silicon transistor and light‐emitting diode on flexible and stretchable composite, respectively. 相似文献
943.
Yong Hoon Choi Joo Hyun Ryu Sea Woong Lee Kyooyoung Lee Byeong Joo Lee Jin-Kyung Kim 《Materials Science & Technology》2019,35(17):2092-2100
ABSTRACTThe present work reports the effect of different initial microstructures on reverse transformation kinetics and morphologies of austenite formed during intercritical annealing in Fe-0.14C-7Mn-1Si (wt-%) medium Mn steel. Three different initial microstructures were produced by cold-rolling and cold-rolling followed by austenitisation at 820°C and 900°C. The specimen austenitised at higher temperature shows lath-type austenite after intercritical annealing. The difference in austenitisation temperature leads to different Mn distribution in martensitic initial microstructures, thereby leading to a difference in morphology of austenite. The inhomogeneous Mn profiles in initial microstructures also affect reverse transformation kinetics of austenite upon intercritical annealing. The presence of Mn-enriched regions accelerates austenite growth at an early stage of intercritical annealing but retards the transformation kinetics afterwards.This paper is part of a Thematic Issue on Medium Manganese Steels. 相似文献
944.
Ungsoo Kim Yongjoon Cho Dasom Jeon Yongchul Kim Sanghyeon Park Jihyung Seo Junghyun Lee Nam Khen Oh Geunsik Lee Jungki Ryu Changduk Yang Hyesung Park 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(11)
The functionalization of graphene has been extensively used as an effective route for modulating the surface property of graphene, and enhancing the dispersion stability of graphene in aqueous solutions via functionalization has been widely investigated to expand its use for various applications across a range of fields. Herein, an effective approach is described for enhancing the dispersibility of graphene in aqueous solutions at different pH levels via non‐covalent zwitterion functionalization. The results show that a surfactant with electron‐deficient carbon atoms in its backbone structure and large π–π interactive area enables strong interactions with graphene, and the zwitterionic side terminal groups of the molecule support the dispersibility of graphene in various pH conditions. Experimental and computational studies confirm that perylene diimide amino N‐oxide (PDI–NO) allows efficient functionalization and pH‐independent dispersion of graphene enabled by hydration repulsion effects induced by PDI–NO. The PDI–NO functionalized graphene is successfully used in the oxygen evolution reaction as an electron mediator for boosting the electrocatalytic activity of a Ru‐based polyoxometalate catalyst in an acidic medium. The proposed strategy is expected to bring significant advances in producing highly dispersible graphene in aqueous medium with pH‐independent stability, thus broadening the application range of graphene. 相似文献
945.
This paper presents an RSN Tool to generate input datasets for testing RFID middleware. As RFID middleware takes an important role in entire RFID systems, its performance should be carefully evaluated under various business conditions. In general, evaluation of the RFID middleware requires a huge cost because the numerous RFID readers and tags need to be deployed to acquire the tag event stream. To facilitate low-cost testing of the middleware, we propose the RSN Tool which provides means of designing a virtual RFID infrastructure and generates a tag event stream automatically for the virtual infrastructure. Using the RSN Tool, we can easily obtain a semantically valid dataset, which captures both physical characteristics of RF communications and business activities of tags’ movements. This is a major differentiation point of our work compared from previous works, which merely create the randomized dataset based on a set of virtual RFID readers. We also discuss a step-by-step usage of the RSN Tool from the creation of a virtual infrastructure to the generation of tag events. The experimental analysis shows that the RSN Tool can create the near-real dataset, which closely reflects business activities of the real RFID infrastructure. 相似文献
946.
Hee Kwon Jun Suk Yong Jung Tae Jin Lee Chung Kul Ryu Jae Chang Kim 《Catalysis Today》2003,87(1-4):3-10
Zn–Ti-based sorbents promoted with cobalt and nickel additive were prepared by simple physical mixing of single oxides. Their capacities for removing H2S and NH3 simultaneously, emitted from coal gasifiers, were investigated in a micro-reactor at 1 atm and 650 °C. NH3 within the fuel gases did not affect the sulfur removing capacity of the Zn–Ti-based sorbent. The additives, cobalt and nickel, were found to be active components in NH3 decomposition as well as H2S absorption, while major components such as ZnO and TiO2 did not show any activity in the NH3 decomposition reaction. NH3 was decomposed over both oxide and sulfide forms of the additives, even though the NH3 decomposition ability of their sulfides dramatically decreased in the presence of H2 gas owing to the equilibrium limitation of NH3 decomposition. In the case of oxide forms, cobalt oxide showed excellent NH3 decomposition capacity regardless of H2 concentrations, while the capacity of nickel oxide depended on the H2 concentrations. 相似文献
947.
The surface modification of monodisperse‐crosslinked polymeric microspheres was carried out by introducing hydroxyl groups on the surface and utilizing the redox initiation system. The emulsions of the second monomer mixture were swollen into the monodisperse PS seed particles. The hydroxyl groups were introduced by hydrolysis of the acetate groups on the surface of microspheres. Ceric ammonium sulfate in sulfuric acid solution was employed to graft the acrylic monomer onto the polymeric microspheres. The surface characteristics of the surface‐modified particles were confirmed by FTIR, SEM, and TGA measurements. From the FE‐TEM image, a uniform coating layer was confirmed on the surface of microsphere. In DSC analysis, only an exothermal peak appeared when high content of DVB was used in the seeded polymerization, while, Tgs emerged after hydrolysis and graft polymerization using the low content of DVB in the second monomer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1349–1356, 2006 相似文献
948.
Solid structure formation in the drying step for wet spinning of poly(1‐oxotrimethylene) using as a solvent an aqueous solution of complex metal salts of calcium chloride/zinc chloride was studied. Because the degree of structural densification and the crystal structure both differ depending on the drying temperature, the drying temperature had a major effect on the drawing behavior and the strength achieved after drawing. With higher drying temperature, the denseness increased due to smaller voids in the dried undrawn fiber, while there was also a tendency toward higher strength with respect to the draw ratio. However, an excessively high drying temperature altered the crystal structure from a rough crystalline form to a dense crystalline form and reduced both the maximum draw ratio and strength. Mechanical cleavage of the molecular chains occurred between the ethylene groups and carbonyl groups of the main chains in the drawing step. This cleavage made it possible to suppress the inhibition of drawing due to entanglement of the molecular chains, thereby enabling superdrawing to afford a high performance fiber. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 446–452, 2004 相似文献
949.
Sangjin Ryu In-Jung Kim 《International Journal on Document Analysis and Recognition》2014,17(1):79-89
Discrimination of confusing characters is very important in recognition of character sets containing a multitude of similar characters. Confusing characters have very similar shapes and are separated by only a small difference. For a successful discrimination, we need to focus on that difference. However, the small difference can be reduced or even lost during the feature extraction process. In such a case, further analysis after the feature extraction rarely succeeds. This paper proposes a discriminative nonlinear normalization algorithm to improve discrimination ability. The proposed method emphasizes the difference between confusing characters. It measures the importance of each region in the discrimination of confusing characters. Then, it resamples the image according to the regional importance measure. As a result, it expands important regions but shrinks less important regions. Since it emphasizes important regions in the preprocessing step, it does not suffer from the information loss during the feature extraction. In experiments, the proposed method successfully detected and expanded important regions. In handwritten Hangul recognition, the proposed method outperformed other two recently developed pair-wise discrimination methods. On SERI95a data set, it improved the recognition rate from 87.69 to 90.11 %, achieving a 19.66 % error reduction rate. 相似文献
950.
Highly porous poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVdF–HFP)‐based polymer membranes filled with fumed silica (SiO2) were prepared by a phase‐inversion technique, and films were also cast by a conventional casting method for comparison. N‐Methyl‐2‐pyrrolidone as a solvent was used to dissolve the polymer and to make the slurry with SiO2. Phase inversion occurred just after the impregnation of the applied slurry on a glass plate into flowing water as a nonsolvent, and then a highly porous structure developed by mutual diffusion between the solvent and nonsolvent components. The PVdF–HFP/SiO2 cast films and phase‐inversion membranes were then characterized by an examination of the morphology, thermal and crystalline properties, absorption ability of an electrolyte solution, ionic conductivity, electrochemical stability, and interfacial resistance with a lithium electrode. LiPF6 (1M) dissolved in a liquid mixture of ethylene carbonate and dimethyl carbonate (1:1 w/w) was used as the electrolyte solution. Through these characterizations, the phase‐inversion polymer electrolytes were proved to be superior to the cast‐film electrolytes for application to rechargeable lithium batteries. In particular, phase‐inversion PVdF–HFP/SiO2 (30–40 wt %) electrolytes could be recommended to have optimum properties for the application. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 140–148, 2006 相似文献