• Smart Structures and Systems
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• v.19 no.1
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• pp.47-56
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• 2017

Considerable achievements in developing structural regulators as an important method for vibration control have been made over the last few decades. The use of large quantities of cables in traditional wired control systems to connect sensors, controllers, and actuators makes the structural regulators complicated and expensive. A wireless decentralized control experimental platform based on Wi-Fi unit is designed and implemented in this study. Centralized and decentralized control strategies as sample controllers are employed in this control system. An optimal control algorithm based on Kalman estimator is embedded in the dSPACE controller and the DSP controller. To examine the performance of this control scheme, a three-story steel structure is developed with active mass dampers installed on each floor as the wireless communication platform. Experimental results show that the wireless decentralized control exhibits good control performance and has various potential applications in industrial control systems. The proposed experimental system may become a benchmark platform for the validation of the corresponding wireless control algorithm.

• Nuclear Engineering and Technology
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• v.56 no.8
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• pp.2937-2947
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• 2024

The Republic of Korea is performing independent national inspections under the IAEA's State System of Accounting for and Control (SSAC), and developing an evaluation methodology for the material unaccounted for (MUF) to reinforce capabilities with the purpose of assessment for the accounting system of the facility handling bulk nuclear materials. In relation to this, a new approach for MUF evaluation was proposed in this study based on the guide to the expression of uncertainty in measurement (GUM). Both the conventional MUF evaluation method and the GUM method were applied to a hypothetical list of inventory items including material balance. Considering the ease of uncertainty propagation according to the GUM, it was assumed that independent uncertainty factors correspond to random factors, while correlated uncertainty factors correspond to systematic factors. The total MUF uncertainties were similar for both methods; however, it was verified that some uncertainties were affected by the measurement procedure in the GUM method. Furthermore, the GUM method was found to be more conducive to conducting a factor analysis for the MUF uncertainty. It was therefore concluded that application of the GUM approach could be beneficial in cases of national safeguard inspections where factor analysis is required for MUF assessment.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.1
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• pp.17-29
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• 2003

This paper preliminarily investigates the effectiveness of various control systems, such as passive, active, semiactive and hybrid control, for seismic protection of cable-stayed bridges by examining the ASCE first generation benchmark problem for a cable-stayed bridge. This benchm.0.00000ark problem considers the cable-stayed bridge that is scheduled for completion in Missouri, USA In 2003. Seismic considerations were strongly considered in the design of this bridge due to location of the bridge and its critical role as a principal crossing of the Mississippi River. Based on detailed drawings of this cable-stayed bridge, a three-dimensional linearized evaluation model has been developed to represent the complex behavior of the bridge. A set of eighteen evaluation criteria has been developed to evaluate the capability of each control system. In this study, four passive control systems, one active control system, two semiactive control systems and three hybrid control systems are considered. Numerical simulation results show that all the control systems are effective in reducing the responses of the benchmark cable-stayed bridge under the historical earthquakes. To get good performance, however, the passive control systems need quite large control forces compared to other control systems. The simulation results also demonstrate that the passive, semiactive and hybrid control systems are robust to the stiffness uncertainty of the structure. Therefore, the semiactive and hybrid control systems are more appropriate in real applications for full-scale civil infrastructures.

• Smart Structures and Systems
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• v.8 no.1
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• pp.119-137
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• 2011

A bio-inspired two-mode structural health monitoring (SHM) system based on the Na$\ddot{i}$ve Bayes (NB) classification method is discussed in this paper. To implement the molecular biology based Deoxyribonucleic acid (DNA) array concept in structural health monitoring, which has been demonstrated to be superior in disease detection, two types of array expression data have been proposed for the development of the SHM algorithm. For the micro-vibration mode, a two-tier auto-regression with exogenous (AR-ARX) process is used to extract the expression array from the recorded structural time history while an ARX process is applied for the analysis of the earthquake mode. The health condition of the structure is then determined using the NB classification method. In addition, the union concept in probability is used to improve the accuracy of the system. To verify the performance and reliability of the SHM algorithm, a downscaled eight-storey steel building located at the shaking table of the National Center for Research on Earthquake Engineering (NCREE) was used as the benchmark structure. The structural response from different damage levels and locations was collected and incorporated in the database to aid the structural health monitoring process. Preliminary verification has demonstrated that the structure health condition can be precisely detected by the proposed algorithm. To implement the developed SHM system in a practical application, a SHM prototype consisting of the input sensing module, the transmission module, and the SHM platform was developed. The vibration data were first measured by the deployed sensor, and subsequently the SHM mode corresponding to the desired excitation is chosen automatically to quickly evaluate the health condition of the structure. Test results from the ambient vibration and shaking table test showed that the condition and location of the benchmark structure damage can be successfully detected by the proposed SHM prototype system, and the information is instantaneously transmitted to a remote server to facilitate real-time monitoring. Implementing the bio-inspired two-mode SHM practically has been successfully demonstrated.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.228-230
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• 2002

We present a new low power scan testing and test data compression method for System-On-a-Chip (SOC). The don't cares in unspecified scan vectors are mapped to binary values for low power and encoded by adaptive encoding method for higher compression. Also, the scan-in direction of scan vectors is determined for low power. Experimental results for full-scanned versions of ISCAS 89 benchmark circuits show that the proposed method has both low power and higher compression.

• Proceedings of the IEEK Conference
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• 2000.11d
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• pp.85-88
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• 2000

We present a new approach to analyzing the dynamic false contour noise of AC plasma display panels (PDP), which is known to degrade the image quality severely. Compared with the existing methods that consider only the amount of light emission from PDP during 1 field time, the proposed approach uses the impulse response model of the human vision system and estimates how the human beings actually feel as the function of time. Experimental results using various benchmark sub-field scan algorithms are included.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.190-192
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• 2012

In this paper, we present theoretical queuing analysis for hybrid overlay/underlay Cognitive Radio (CR) system by applying M/M/1 queuing model where the rate of arrival and the service capacity are subject to Poisson alterations. Numerical results are used to prove a high degree of accuracy for the derived expressions. The result can be used as a benchmark to evaluate the performance of a hybrid overlay/underlay CR system.

• Journal of Information Processing Systems
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• v.11 no.2
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• pp.229-238
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• 2015

Web shells are programs that are written for a specific purpose in Web scripting languages, such as PHP, ASP, ASP.NET, JSP, PERL-CGI, etc. Web shells provide a means to communicate with the server's operating system via the interpreter of the web scripting languages. Hence, web shells can execute OS specific commands over HTTP. Usually, web attacks by malicious users are made by uploading one of these web shells to compromise the target web servers. Though there have been several approaches to detect such malicious web shells, no standard dataset has been built to compare various web shell detection techniques. In this paper, we present a collection of web shell files, WebSHArk 1.0, as a standard dataset for current and future studies in malicious web shell detection. To provide baseline results for future studies and for the improvement of current tools, we also present some benchmark results by scanning the WebSHArk dataset directory with three web shell scanning tools that are publicly available on the Internet. The WebSHArk 1.0 dataset is only available upon request via email to one of the authors, due to security and legal issues.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.486-492
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• 2011

In this paper we analyzed performance of Andriod's Davik virtual machine(VM) using standard benchmark and compared the result with the embedded Java virtual machine. We used a well known benchmark suit named SPECJVM for the measurement. For the fair comparison, Sun Java embedded JVM is ported and the same benchmark is ported on it. The Odriod smartphone hardware platform is used as the target hardware. We have added a Just-In-Time compiler to Dalvik, which is not supported in the recent Android release, and measured performance improvement. The experiment result show that Dalvik achieved 15% and Dalvik with JIT shows 63% of the Sun's JVM performance.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.2
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• pp.183-194
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• 2002

The clustering environment with heterogeneous workstations provides the cost effectiveness and usability for executing applications in parallel. Load balancing is considered a necessary feature for a cluster of heterogeneous workstations to minimize the turnaround time. Previously, static load balancing that assigns a predetermined weight for the processing capability of each workstation, or dynamic approaches which execute a benchmark program to get relative processing capability of each workstation were proposed. The execution of the benchmark program, which has nothing to do with the application being executed, consumes the computation time and the overall turnaround time is delayed. In this paper, we present efficient methods for task distribution and task migration, based on the relative load index. We designed and implemented a load balancing system for the clustering environment with heterogeneous workstations. Turnaround times of our methods and the round-robin approach, as well as the load balancing method using a benchmark program, were compared. The experimental results show that our methods outperform all the other methods that we compared.