• Structural Engineering and Mechanics
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• 제65권5호
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• pp.535-546
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• 2018

The objective of this study is to understand the behaviour of hollow core slabs strengthened with FRP and hybrid techniques through numerical and analytical studies. Different strengthening techniques considered in this study are (i) External Bonding (EB) of Carbon Fiber Reinforced Polymer (CFRP) laminates, (ii) Near Surface Mounting (NSM) of CFRP laminates, (iii) Bonded Overlay (BO) using concrete layer, and (iv) hybrid strengthening which is a combination of bonded overlay and NSM or EB. In the numerical studies, three-dimensional Finite Element (FE) models of hollow core slabs were developed considering material and geometrical nonlinearities, and a phased nonlinear analysis was carried out. The analytical calculations were carried out using Response-2000 program which is based on Modified Compression Field Theory (MCFT). Both the numerical and analytical models predicted the behaviour in agreement with experimental results. Parametric studies indicated that increase in the bonded overlay thickness increases the peak load capacity without reducing the displacement ductility. The increase in FRP strengthening ratio increased the capacity but reduced the displacement ductility. The hybrid strengthening technique was found to increase the capacity of the hollow core slabs by more than 100% without compromise in ductility when compared to their individual strengthening schemes.

• Smart Structures and Systems
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• 제16권6호
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• pp.1107-1132
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• 2015

A damage detection algorithm based on neuro fuzzy hybrid system is presented in this study for location and severity predictions of cracks in beam-like structures. A combination of eigenfrequencies and rotation deviation curves are utilized as input to the soft computing technique. Both single and multiple damage cases are considered. Theoretical expressions leading to modal properties of damaged beam elements are provided. The beam formulation is based on Euler-Bernoulli theory. The cracked section of beam is simulated employing discrete spring model whose compliance is computed from stress intensity factors of fracture mechanics. A hybrid neuro fuzzy technique is utilized to solve the inverse problem of crack identification. Two different neuro fuzzy systems including grid partitioning (GP) and subtractive clustering (SC) are investigated for the highlighted problem. Several error metrics are utilized for evaluating the accuracy of the hybrid algorithms. The study is the first in terms of 1) using the two models of neuro fuzzy systems in crack detection and 2) considering multiple damages in beam elements employing the fused neuro fuzzy procedures. At the end of the study, the developed hybrid models are tested by utilizing the noise-contaminated data. Considering the robustness of the models, they can be employed as damage identification algorithms in health monitoring of beam-like structures.

• Applied Chemistry for Engineering
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• 제5권5호
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• pp.857-861
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• 1994

UV curable hybrid systems have been investigated in the urethane acrylate based formulations where potentially irritant acrylate monomers have been substituted by vinyl ethers. Generally, among the systems studied, coating properties of hybrid system are superior to those of free radical hut inferior to those of cationic systems. When the content of acrylic oligomer is above 70%, however, hybrid system could render an excellent combination of coating and curing properties which outperforms both cationic and free radical systems. Photo-DSC has been used to follow the progress of crosslinking of various coating systems. Results imply that the critical factors in determining the curing rates of coating formulations are different depending upon the formulation characteristics. In the same type of hybrid formulations, the monomer/oligomer ratio rather than photoinitiator efficiency is the critical factor determining the curing rate of the systems.

• Journal of the Korean Operations Research and Management Science Society
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• 제21권3호
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• pp.47-61
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• 1996

An ATM switch must deal with various kinds of input sources having different traffic characteristics and it must guarantee very small value of cel loss probability, about 10$^{8}$ -10$^{12}$ , to deal with loss-sensitive traffics. In order to estimate such a rate event probability with simulation procedure, a variance reduction technique is essential for obtaining an appropriate level of precision with reduced cost. In this paper, we propose a hybrid simulation technique to achieve reduction of variance of cell loss probability estimator, where hybrid means the combination of analytical method and simulation procedure. A discrete time queueing model with multiple input sources and a finite shared buffer is considered, where the arrival process at an input source and a finite shared buffer is considered, where the arrival process at an input source is governed by an Interrupted Bernoulli Process and the service rate is constant. We deal with heterogeneous input sources as well as homogeneous case. The performance of the proposed hybrid simulation estimator is compared with those of the raw simulation estimator and the importance sampling estimator in terms of variance reduction ratios.

• IEMEK Journal of Embedded Systems and Applications
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• 제11권2호
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• pp.67-78
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• 2016

The emerging Spin-Transfer Torque RAM (STT-RAM) is a promising component that can be used to improve the efficiency as a result of its high storage density and low leakage power. However, the state-of-the-art STT-RAM is not ready to replace SRAM technology due to the negative effect of its write operations. The write operations require longer latency and more power than the same operations in SRAM. Therefore, a hybrid cache with SRAM and STT-RAM technologies is proposed to obtain the benefits of STT-RAM while minimizing its negative effects by using SRAM. To efficiently use of the hybrid cache, it is important to place write intensive data onto the cache. Such data should be placed on SRAM to minimize the negative effect. Thus, we propose a technique that optimizes placement of data in main memory. It drives the proper combination of advantages and disadvantages for SRAM and STT-RAM in the hybrid cache. As a result of the proposed technique, write intensive data are loaded to SRAM and read intensive data are loaded to STT-RAM. In addition, our technique also optimizes temporal locality to minimize conflict misses. Therefore, it improves performance and energy consumption of the hybrid cache architecture in a certain range.

• Journal of computational fluids engineering
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• 제19권2호
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• pp.72-78
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• 2014

A hybrid particle-mesh method as the combination between the Vortex-In-Cell (VIC) method and penalization method has been achieved in recent years. The VIC method, which is based on the vorticity-velocity formulation, offers particle-mesh algorithms to numerically simulate flows past a solid body. The penalization method is used to enforce boundary conditions at a body surface with a decoupling between body boundaries and computational grids. The main advantage of the hybrid particle-mesh method is an efficient implementation for solid boundaries of arbitrary complexity on Cartesian grids. However, a numerical simulation of flows in large domains is still not too easy. In this study, a multi-domain approach is thus proposed to further reduce computation cost and easily implement it. We validate the implementation by numerical simulations of an incompressible viscous flow around an impulsively started circular cylinder.

• The Transactions of the Korean Institute of Electrical Engineers D
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• 제49권11호
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• pp.599-609
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• 2000

The new design methodology of a hybrid fuzzy controller by means of the genetic algorithms is presented. First, a hybrid fuzzy controller(HFC) related to the optimal estimation of control parameters is proposed. The control input for the system in the HFC combined PID controller with fuzzy controller is a convex combination of the FLC's output and PID's output by a fuzzy variable, namely, membership function of weighting coefficient. Second, an auto-tuning algorithms utilizing the simplified reasoning method and genetic algorithms is presented to automatically improve the performance of hybrid fuzzy controller. Especially, in order to auto-tune scaling factors and PID parameters of HFC using GA, three kinds of estimation modes such as basic, contraction, and expansion mode are effectively utilized. The proposed HFC is evaluated and discussed to show applicability and superiority with the and of three representative processes.

• Plant Resources
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• 제6권2호
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• pp.144-148
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• 2003

Germination efficiency, such as days to germination and conditions for the hybrid seeds, was tested after hybrid seeds were sown on the medium. Seeds were germinated from 67 to 126 days after seeding in all cross combinations, and germination condition was different among hybrid combinations. There was big difference on days to germination based on the different media, that is, days to germination in the hyponex medium was shorter than that in the Knudson C medium. Mutants such as MMS and NaN$_3$ were used to cause mutation. Germination occurred with 0.1 % NaN$_3$ and MMS. However, even though germination occurred in other treatments (0.01 % and 0.2% of NaN$_3$ and MMS), brownish phenomenon was intense, or did not proceed and got worse after 4-5 months of seeding. In addition, it was performed to choose appropriate medium for the growth of Cymbidium rhizome whose media adaptability is more different than other orchids. Different concentration of NAA and Kinetin was used. As a result, C. goeringii hybrid showed difference for the concentration of NAA and Kinetin combination.

• The Transactions of the Korean Institute of Power Electronics
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• 제23권2호
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• pp.112-120
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• 2018

This work presents a hybrid generator, which is a combination of a permanent magnet (PM) and winding structure with a PM exciter. The field winding of the proposed hybrid generator is fed by the PM exciter and the embedded current controller, which is installed in the generator shaft. In the no-load condition, the output voltage of the generator is produced by the PM flux of the generator without any field winding current. The field winding current produces an insufficient flux to retain the output voltage of the generator when the load is injected. The total efficiency can be increased from the PM exciter and PM flux of the generator. The field current has to be controlled inside the proposed generator. The generated power from the PM exciter is used to excite the field flux of the generator. The embedded current controller is commanded by the external voltage controller using the infrared wireless method. The 10 kW prototype hybrid PM generator is designed and tested to verify the effectiveness of the proposed system. The experimental results are compared with those of the winding generator with PM exciter.

• Journal of the Korean Institute of Intelligent Systems
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• 제11권3호
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• pp.200-207
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• 2001

In this paper, we propose an HMM(Hidden Markov modeJ)-MLP(Multi-layer perceptron) hybrid model for recognizing legal words on the English bank check. We adopt an explicit segmentation-based word level architecture to implement an HMM engine with nonscaled and non-normalized symbol vectors. We also introduce an MLP for implicit segmentation-based word recognition. The final recognition model consists of a hybrid combination of the HMM and MLP with a new hybrid probability measure. The main contributions of this model are a novel design of the segmentation-based variable length HMMs and an efficient method of combining two heterogeneous recognition engines. ExperimenLs have been conducted using the legal word database of CENPARMI with encouraging results.