• Computers and Concrete
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• v.5 no.2
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• pp.101-116
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• 2008

The microscopic determination of air void characteristics in hardened concrete, defined in EN 480-11 as the linear-traverse method, is an extremely time-consuming and tedious task. Over past decades, several researchers have proposed relatively expensive mechanical automated systems which could replace the human operator in this procedure. Recently, the appearance of new high-resolution flatbed scanners has made it possible for the procedure to be automated in a fully-computerized and thus cost-effective way. The results of our work indicate the high sensitivity of such image analysis automated systems firstly to the quality of sample surface preparation, secondly to the selection of the air void threshold value, and finally to the selection of the probe system. However, it can be concluded that in case of careful validation and the use of the approach which is proposed in the paper, such automated systems can give very good estimate of the air void system parameters, defined in EN 480-11. The amount of time saved by using such a procedure is immense, and there is also the possibility of using alternative stereological methods to assess other, perhaps also important, characteristics of air void system in hardened concrete.

• Computers and Concrete
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• v.20 no.6
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• pp.719-729
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• 2017

A considerable research is available on the seismic response of Reinforced Concrete (RC) shear wall-frame buildings, but the studies on the reliability of such buildings, with the consideration of human error, are limited. In the present study, a detailed procedure for reliability assessment of RC shear wall-frame building subjected to earthquake loading against serviceability limit state is presented. Monte Carlo simulation was used for the reliability assessment. The procedure was implemented on a 10-story RC building to demonstrate that the shear walls improve the reliability substantially. The annual and life-time failure probabilities of the studied building were estimated by employing the information of the annual probability of earthquake occurrence and the design life of the building. A simple risk-based cost assessment procedure that relates both the structural life-time failure probability and the target reliability with the total cost of the building was then presented. The structural failure probability (i.e., the probability of exceeding the allowable drift) considering human errors was also studied. It was observed that human error in the estimation of total load and/or concrete strength changes the reliability sharply.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1169-1172
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• 1996

A time-optimal control law for quick, strongly nonlinear systems has been developed and demonstrated. This procedure involves the utilization of neural networks as state feedback controllers that learn the time-optimal control actions by means of an iterative minimization of both the final time and the final state error for the known and unknown systems with constrained inputs and/or states. The nature of neural networks as a parallel processor would circumvent the problem of "curse of dimensionality". The control law has been demonstrated for a velocity input type motor identified by a genetic algorithm called GENOCOP.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.219-224
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• 1988

A decentralised computational procedure is proposed for the optimal feedback gain matrix of large-scale discrete-time systems with time-delays. The constant feedback gain matrix is computed from the optimal state and input trajectries obtained hierarchically by the interaction prediction method. All the calculation in this approach are done off-line. The resulting gains are optimal for all the initial conditions. The interaction prediction method is applied to time-delay large-scale systems with general structures by extending the dimensions of coupling matices. A numerical exampie illustrates the algorithm.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.237-237
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• 2000

In this paper, The modified dead-time compensator for plants with an integrator and long dead time is proposed. The design procedure takes account of the closed-loop performance and robustness. The tuning of the controller can be done using some information about the plant and its uncertainties. The proposed controller is compared to others recently presented in the literature. Some simulation results verify good closed-performance and robustness of the proposed DTC.

• Imaging Science in Dentistry
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• v.32 no.4
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• pp.195-200
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• 2002

Purpose: To evaluate the computed tomographic appearances of post-operative maxillary sinuses. Materials and Methods: 33 asymptomatic cases of post-operative maxillary sinus without evidence of any pathologic changes and clinical symptoms were selected. CT images were classified as opacification, soft tissue shadow, anterior wall depression, naso-antral communication, and compartmentalization. The relationships between the CT image and the age of patients at the time of operatation, and between the CT image and the duration of time elapsed since the surgical procedure were evaluated. Results: The most commonly presented radiological characteristics that occurred after the Caldwell-Luc procedure were opacification and soft tissue shadow. Anterior wall depression and naso-antral communication were radiographic indications that a Caldwell-Luc operation had been carried out. The age of patients when they had been first operated on, and the duration between the surgical procedure and the time of evaluation had no effect on the CT appearances of normal changes. In cases involving a longer time interval between the antral surgery and evaluation, the anterior wall depression with bony healing was more commonly observed than soft tissue healing. Conclusion: The radiographic information regarding the normal healing state using computed tomography can distinguish post-operative changes from inflammatory and cystic disease in patients who have undergone a Caldwell-Luc type of radical maxillary antrostomy.

• Journal of Communications and Networks
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• v.18 no.1
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• pp.65-74
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• 2016

Ship ad-hoc network (SANET) extends the coverage of the maritime communication among ships with the reduced cost. To fulfill the growing demands of real-time services, the SANET requires an efficient clock time synchronization algorithm which has not been carefully investigated under the ad-hoc maritime environment. This is mainly because the conventional algorithms only suggest to decrease the beacon collision probability that diminishes the clock drift among the units. However, the SANET is a very large-scale network in terms of geographic scope, e.g., with 100 km coverage. The key factor to affect the synchronization performance is the signal propagation delay, which has not being carefully considered in the existing algorithms. Therefore, it requires a robust multi-hop synchronization algorithm to support the communication among hundreds of the ships under the maritime environment. The proposed algorithm has to face and overcome several challenges, i.e., physical clock, e.g., coordinated universal time (UTC)/global positioning system (GPS) unavailable due to the atrocious weather, network link stability, and large propagation delay in the SANET. In this paper, we propose a logical clock synchronization algorithm with multi-hop function for the SANET, namely multi-hop clock synchronization for SANET (MCSS). It works in an ad-hoc manner in case of no UTC/GPS being available, and the multi-hop function makes sure the link stability of the network. For the proposed MCSS, the synchronization time reference nodes (STRNs) are efficiently selected by considering the propagation delay, and the beacon collision can be decreased by the combination of adaptive timing synchronization procedure (ATSP) with the proposed STRN selection procedure. Based on the simulation results, we finalize the multi-hop frame structure of the SANET by considering the clock synchronization, where the physical layer parameters are contrived to meet the requirements of target applications.

• The KIPS Transactions:PartD
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• v.16D no.4
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• pp.621-630
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• 2009

In recent years, there have been many attempts to connect the latest RFID (Radio Frequency Identification) technology with EIS (Enterprise Information System) and utilize them. However, in most cases the focus is only on the simultaneous multiple reading capability of the RFID technology neglecting the management of massive data created from the reader. As a result, it is difficult to obtain time-related information such as flow prediction and analysis in process control. In this paper, we suggest a new method called 'procedure tree', an enhanced and complementary version of PathTree which is one of RFID data mining techniques, to manage massive RFID data sets effectively and to perform a real-time process control efficiently. We will evaluate efficiency of the proposed system after applying real-time process management system connected with the RFID-based EIS. Through the suggested method, we are able to perform such tasks as prediction or tracking of process flow for real-time process control and inventory management efficiently which the existing RFID-based production system could not have done.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.789-794
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• 2002

The relationship is investigated between material modeling of concrete and the evaluation procedure of thermal stress by the hydration heat. In this respect, some important points are suggested to which special attention should be paid to reasonably evaluate the thermal stress using the widely-used structural analysis programs. This study indicates that proper material model should be used to draw incremental stress evaluation that takes into account the change of elastic modulus with time. Some correction techniques are also presented when using the program that don't have proper built-in procedure for the calculation of the thermal stress.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.515-518
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• 2002

This paper presents the iterative procedure with the concept of expanded waves in the spectral and spatial domains using the fast modal algorithm. We presents its applications to microwave integrated circuits on resistive substrate. The advantage is a reduction in computation time. These calculated results are checked by comparison with the experimental and simulated results by Sonnet and Momentum program.