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991.
Andi Haris Nam Seo Goo Hoon Cheol Park Kwang Joon Yoon 《Computational Materials Science》2004,30(3-4):474-481
This paper focuses on the modeling and analysis of Lightweight Piezoceramic Composite Actuators (LIPCA) for developmental purposes. A simple analytical model and a numerical model for predicting the displacement of the actuators due to both an applied input voltage and transverse load to the piezoelectric ceramic layer are presented. The analytical model describing the laminated beam actuation results in two primary design parameters, an actuation coefficient of a laminated beam Culb and the bending stiffness of a laminated beam EIlb. The Culb is a parameter when maximum displacement is required. The bending stiffness affects the displacement performance when a transverse load is applied to the actuators. An experiment was performed to verify the proposed laminated beam model. The numerical model, a NASTRAN finite element model, is used to assess the effect of initial dome heights of actuators on the displacement. An increase in the initial dome height produces a positive effect for the low anisotropic actuators and gives a negative effect for the high anisotropic actuators. In conclusion, the results indicate that designing to maximize the Culb, the EIlb, and the initial dome height of the low anisotropic actuators could generate LIPCA-type actuators with larger displacement and higher force. 相似文献
992.
Phase-separation behavior of polystyrene (PS) and poly(methyl methacrylate) (PMMA) 1:1 blend film has been studied as a function of film thickness and component by adding PS-b-PMMA diblock copolymer. After annealing, PS is phase-separated into circular-shaped bumps on a PMMA layer. The bump number is inversely proportional to the film thickness in log-log plot while the slope is invariable for the blends with and without 5% PS-b-PMMA diblock copolymer. The bump size and inter-bump spacing are also affected by both the film thickness and addition of the block copolymer. 相似文献
993.
OBJECTIVE: The effects of handle friction and torque direction on muscle activity and torque are empirically investigated using cylindrical handles. BACKGROUND: A torque biomechanical model that considers contact force, friction, and torque direction was evaluated using different friction handles. METHODS: Twelve adults exerted hand torque in opposite directions about the long axis of a cylinder covered with aluminum or rubber while grip force, torque, and finger flexor electromyography (EMG) were recorded. In addition, participants performed grip exertions without torque, in which they matched the EMG level obtained during previous maximum torque exertions, to allow us to determine how grip force was affected by the absence of torque. RESULTS: (a) Maximum torque was 52% greater for the high-friction rubber handle than for the low-friction aluminum handle. (b) Total normal force increased 33% with inward torque (torque applied in the direction fingertips point) and decreased 14% with outward torque (torque in the direction the thumb points), compared with that with no torque. Consequently, maximum inward torque was 45% greater than maximum outward torque. (c) The effect of torque direction was greater for the high-friction rubber handle than for the low-friction aluminum handle. CONCLUSION: The results support the proposed model, which predicts a large effect of torque direction when high-friction handles are gripped. APPLICATION: Designing tasks with high friction and inward rotations can increase the torque capability of workers of a given strength, or reduce required muscle activities for given torque exertions, thus reducing the risk of fatigue and musculoskeletal disorders. 相似文献
994.
We investigated the effect of a firm's resource capabilities and interaction processes on the success of IT outsourcing. Grounded in available literature on outsourcing relationship and process theory as well as a resource-based view of the IT resource capability, a conceptual model was composed to examine the causal structure of capability, process, and relationship in IT outsourcing. We identified the firm's resource capability factors and, based on the premise that relationship intensity should be affected by the IT outsourcing process, we developed a first-order factor analysis of resource capabilities in the interactions between the outsourcer and provider. Results of empirical testing using responses from 267 IT outsourcing project teams in Korea supported most of our hypotheses. The integration of corporate IT resource and capability theories with social exchange theory distinguishes our research from that of others, who have generally treated these theories separately. 相似文献
995.
Neural network modeling of the cellgap process for liquid crystal display fabricated on plastic substrates 总被引:1,自引:1,他引:0
Jung Hwan Lee Dong-Hun Kang Young-Don Ko Jaejin Jang Dae-Shik Seo Ilgu Yun 《Expert systems with applications》2008,35(3):1311-1315
In this paper, a neural network model is presented to characterize the thickness and the uniformity of the cellgap process for flexible liquid crystal display (LCD). Input factors are explored via a D-optimal design with 15 runs and used as training data in the neural network. In order to verify the fitness of the model, three more runs are added as test data. Latin hypercube sampling and error back-propagation algorithm are used to build the model. Latin hypercube sampling is used to generate initial weights and biases of the network. The thickness of cellgap is measured at five points: one at the center and four at the edges. The average thickness is used as cellgap thickness, and the uniformity is obtained by comparing the thickness at the center and edge points. 相似文献
996.
We study how to extend modal type systems based on intuitionistic modal logic S4 or S5 with a subtyping system based on intersection types. In the presence of four type constructors ${\!}\!\rightarrow \!{\!},\,{\!}\wedge {\!},\,\square {}$ , and $\Diamond {}$ , the traditional approach using a binary subtyping relation does not work well because of lack of orthogonality in subtyping rules and presence of a transitivity rule. We adopt the idea from the judgmental formulation of modal logic (Pfenning and Davies in Math Struct Comput Sci 11(4):511–540, 2001) and use subtyping judgments whose definitions express those notions internalized into type constructors directly at the level of judgments. The resultant judgmental subtyping systems admit cut rules similarly to a sequent calculus for intuitionistic logic and play a key role in designing and verifying the relational subtyping systems based on the binary subtyping relation. We use the proof assistant Coq to prove the admissibility of the cut rules and the equivalence between the two kinds of subtyping systems. The lesson from our study is that by using subtyping judgments instead of the binary subtyping relation, we can overcome the limitation usually associated with the syntactic approach to formulating subtyping systems. 相似文献
997.
We present an efficient and robust algorithm for the landmark transfer on 3D meshes that are approximately isometric. Given one or more custom landmarks placed by the user on a source mesh, our method efficiently computes corresponding landmarks on a family of target meshes. The technique is useful when a user is interested in characterization and reuse of application-specific landmarks on meshes of similar shape (for example, meshes coming from the same class of objects). Consequently, across a set of multiple meshes consistency is assured among landmarks, regardless of landmark geometric distinctiveness. The main advantage of our method over existing approaches is its low computation time. Differently from existing non-rigid registration techniques, our method detects and uses a minimum number of geometric features that are necessary to accurately locate the user-defined landmarks and avoids performing unnecessary full registration. In addition, unlike previous techniques that assume strict consistency with respect to geodesic distances, we adopt histograms of geodesic distance to define feature point coordinates, in order to handle the deviation of isometric deformation. This allows us to accurately locate the landmarks with only a small number of feature points in proximity, from which we build what we call a minimal graph. We demonstrate and evaluate the quality of transfer by our algorithm on a number of Tosca data sets. 相似文献
998.
Kyusuk Han Youngjoon Seo Sungjune Yoon James J. Park Taeshik Shon 《Journal of Network and Computer Applications》2011,34(6):1903-1907
Vertical handoff is one of the most important issues in the heterogeneous networks. While Lee et al. introduced a selective advance reservations and resource-aware handoff direction (SARAH) mechanism in order to provide a fast and efficient handoff with combination of layer 2 (L2) and layer 3 (L3) communications, there was a drawback that there was no consideration of handoff between heterogeneous network. In this paper, we improve the mechanism by providing security functions such as the neighbor-mapping server that binds IP address and MAC address with security support. At first, we discuss security issues in SARAH and proposed enhanced protocol. Finally, we show simple implementation results of our design in order to verify the practical aspects of our design. 相似文献
999.
Lee B Yun J Seo J Shim B Shin YG Kim B 《IEEE transactions on visualization and computer graphics》2010,16(6):1525-1532
Volume ray-casting with a higher order reconstruction filter and/or a higher sampling rate has been adopted in direct volume rendering frameworks to provide a smooth reconstruction of the volume scalar and/or to reduce artifacts when the combined frequency of the volume and transfer function is high. While it enables high-quality volume rendering, it cannot support interactive rendering due to its high computational cost. In this paper, we propose a fast high-quality volume ray-casting algorithm which effectively increases the sampling rate. While a ray traverses the volume, intensity values are uniformly reconstructed using a high-order convolution filter. Additional samplings, referred to as virtual samplings, are carried out within a ray segment from a cubic spline curve interpolating those uniformly reconstructed intensities. These virtual samplings are performed by evaluating the polynomial function of the cubic spline curve via simple arithmetic operations. The min max blocks are refined accordingly for accurate empty space skipping in the proposed method. Experimental results demonstrate that the proposed algorithm, also exploiting fast cubic texture filtering supported by programmable GPUs, offers renderings as good as a conventional ray-casting algorithm using high-order reconstruction filtering at the same sampling rate, while delivering 2.5x to 3.3x rendering speed-up. 相似文献
1000.
Jaeha Kim Jong-Phil Kim Changhoon Seo Jeha Ryu 《International Journal of Control, Automation and Systems》2010,8(2):352-360
This paper presents a multiple degree-of-freedom (DOF) energy bounding approach (EBA) for enhancing directional transparency while concurrently guaranteeing stability during multi-DOF haptic interactions. It was observed that the passivity condition for multiple ports may lead to oscillatory limit cycle behavior in some coordinate directions even though the total sum of energy flow-in is positive, meaning that the system is passive. The passivity condition, therefore, needs to be applied to each coordinate in order to avoid oscillatory behavior by ensuring that each energy flow-in is always positive. The EBA is applied to guarantee passivity. For multi-DOF haptic interaction, however, the EBA in each coordinate may distort the direction of the rendered force vector since the EBA may reduce the magnitude of the rendered force and torque vectors. To resolve this problem, a simple projection method is subsequently proposed. The validity of the proposed algorithm is then experimentally confirmed, and a comparative study with previous research is presented. 相似文献