• The Journal of the Korea Contents Association
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• v.9 no.8
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• pp.91-98
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• 2009

This paper presents a solution to error avalanche of deciphering where radio noise brings random bit errors in encrypted image data under ubiquitous environment. The image capturing module is to be made comprising data compression and encryption features to reduce data traffic volume and to protect privacy. Block cipher algorithms may experience error avalanche: multiple pixel defects due to single bit error in an encrypted message. The new fault tolerant scheme addresses error avalanche effect exploiting a three-dimensional data shuffling process, which disperses error bits on many frames resulting in sparsely isolated errors. Averaging or majority voting with neighboring pixels can tolerate prominent pixel defects without increase in data volume due to error correction. This scheme has 33% lower data traffic load with respect to the conventional Hamming code based approach.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.11B
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• pp.956-966
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• 2004

Nowadays, NGN(Next Generation Network) is evolving into network with packet based QoS.\ulcorner This paper presents the recovery method as a selecting way of more efficient path in MPLS network that reduces the service interruption time. In order to increase the efficiency of usage of recovering resource which is one of major functions of disorder recovering, it opens the state information of each Node both to fault detector and bandwidth broker so that it reduces message transmission time for recovery when functional disorder occurs. in addition, by effective management and adjustment of required bandwidth of entire network depending on the changes of traffic load, it improves the efficiency of bandwidth usage. and in MPLS network supporting priority selection function, it allocates domains depending on the traffic relating to priority order to the entire network so that\ulcorner it efficiently allocates proper resources to the restoring process between the entry and the end for the traffic of high priority and for low priority traffic, it restores path oかy inside disordered domain. by doing this, it reduces resetting time and unnecessary massage transmission.

• The Korean Journal of Applied Statistics
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• v.21 no.5
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• pp.813-823
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• 2008

The non-homogeneous Poisson process(NHPP) based software reliability growth models are proved quite successful in practical software reliability engineering. The fault detection rate is usually assumed to be the continuous and monotonic function. However, the fault detection rate can be affected by many factors such as the testing strategy, running environment and resource allocation. This paper describes a parameter estimation of software reliability growth model with change-point problem. We obtain the maximum likelihood estimate(MLE) and least square estimate(LSE), and compare goodness-of-fit.

• Journal of Korea Multimedia Society
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• v.21 no.4
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• pp.450-463
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• 2018

Sound based machine fault diagnosis is the process consisting of detecting automatically the damages that affect the machines by analyzing the sounds they produce during their operating time. The collected sounds being inevitably corrupted by random disturbance, the most important part of the diagnosis consists of discovering the hidden elements inside the data that can reveal the faulty patterns. This paper presents a novel feature extraction methodology that combines various digital signal processing and pattern recognition methods for the analysis of the sounds produced by the drills. Using the Fourier analysis, the magnitude spectrum of the sounds are extracted, converted into two-dimensional vectors and uniformly normalized in such a way that they can be represented as 8-bit grayscale images. Histogram equalization is then performed over the obtained images in order to adjust their very poor contrast. The obtained contrast enhanced images will be used as the features of our diagnosis system. Finally, principal component analysis is performed over the image features for reducing their dimensions and a nonlinear classifier is adopted to produce the final response. Unlike the conventional features, the results demonstrate that the proposed feature extraction method manages to capture the hidden health patterns of the sound.

• Journal of KIISE:Software and Applications
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• v.28 no.10
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• pp.732-742
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• 2001

The concept of an agent has become important in computer science and has been applied to the number of application domains such electronic commerce and information retrieval. But, no one has proposed yet in software test. The test agent system applied the concept of an agent to software test is new test tool. It consists of the User Interface Agent. the Test Case Selection & Testing Agent and the Regression Test Agent. Each of these agents, with their intelligent rules, carry out the tests autonomously by empolying the object-oriented test processes. This system has 2 advantages. Firstly since the tests are carried our autonomously, it minimizes tester interference and secondly, since redundant-free and consistent effective test cases are intellectually selected, the testing time is reduced while the fault detection effectiveness improves. In this paper, by actually showing the testing process being carried out autonomously by the 3 agents that form the TAS, we show that the TAS minimizes tester interference. By also carrying out the 4 different types of experiments on the RE-Rule, CTS-Rule, overall TAS experiment, and the fault-detection effectiveness experiment on the RE-Rule, we show the cut-down on the testing time and improvement in the fault detection effectivity.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.6
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• pp.1496-1521
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• 2012

Uncertainty is ubiquitous in target tracking wireless sensor networks due to environmental noise, randomness of target mobility and other factors. Sensing results are always unreliable. This paper considers unreliability as it occurs in wireless sensor networks and its impact on target-tracking accuracy. Firstly, we map intersection pairwise sensors' uncertain boundaries, which divides the monitor area into faces. Each face has a unique signature vector. For each target localization, a sampling vector is built after multiple grouping samplings determine whether the RSS (Received Signal Strength) for a pairwise nodes' is ordinal or flipped. A Fault-Tolerant Target-Tracking (FTTT) strategy is proposed, which transforms the tracking problem into a vector matching process that increases the tracking flexibility and accuracy while reducing the influence of in-the-filed factors. In addition, a heuristic matching algorithm is introduced to reduce the computational complexity. The fault tolerance of FTTT is also discussed. An extension of FTTT is then proposed by quantifying the pairwise uncertainty to further enhance robustness. Results show FTTT is more flexible, more robust and more accurate than parallel approaches.

• Journal of IKEEE
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• v.24 no.1
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• pp.216-224
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• 2020

This paper proposes an impedance design method of the test device for evaluating Low Voltage Ride Through(LVRT) and High Voltage Ride Through(HVRT) functions. The LVRT/HVRT test device should have ability to generate the fault voltage specified in the grid code for a certain period and to limit the magnitude of the fault current with the design specification. In this paper, the impedance design method for auto transformer is proposed based on a equivalent model of a tap-change auto-transformer during LVRT/HVRT operation. In addition, to generate various fault voltages required the LVRT/HVRT test, tap impedance design in the auto transformer is considered. To verify the validity of the proposed design method, the design process of the 10MVA LVRT/HVRT test device was conducted and the design results was verified through simulation models.

• Journal of Digital Convergence
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• v.11 no.1
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• pp.275-281
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• 2013

This space is for the of your study in English. If simple menu item changes or the addition of check items are necessary on GUI menu of existing test equipments for military facilities that are programmed by using RAD tools such as Visual C++, they should go through complex steps, such as numerous conducting steps, coding, flash design modification, recompiling and distribution. It is cumbersome process and waste much time. Also, on implementing them, it was worried about leaking secrets because a number of military security considerations were included. To solve such as the above problem, we proposed commercial RIA technologies and a COTS fault diagnostic knowledge-based system that implemented by the XML data design technique in this research. The proposed approach solves the problem of existing methods, reduced inspection time, and improved performance, usability, and maintainability.

• Journal of IKEEE
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• v.15 no.4
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• pp.267-273
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• 2011

In hardware design, its stability and reliability are important, because a hardware error can cause serious damages or disaster. To improve stability and reliability, this paper presents the implementation of the hardware verification system using the fault injection method in PC environment. This paper presents a verification platform that can verify hardware system reliably and effectively, through a process to generate faults as well as insert input signals into the actual running system environment. The verification system is configured to connect a PC with a digital I/O card, and it can transmit or receive signals from the target system, as a verifier's intention. In addition, it can generate faults and inject them into the target system. And it can be monitored by displaying the received signals from the target system to the graphical wave signals. We can evaluate its reliability by analyzing the graphical wave signals. In this paper, the proposed verification system has been applied to the FPGA firmware of a nuclear power plant control system. As a result, we found its usefulness and reliability.

• Journal of the Korean earth science society
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• v.25 no.1
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• pp.22-31
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• 2004

Laboratory experiments were conducted in order to find effects of the intermediate principal stress of ${\sigma}_{2}$ on rock fractures and faults. Polyaxial tests were carried out under the most generalized compressive stress conditions, in which different magnitudes of the least and intermediate principal stresses ${\sigma}_{3}$ and ${\sigma}_{2}$ were maintained constant, and the maximum stress ${\sigma}_{1}$, was increased to failure. Two crystalline rocks (Westerly granite and KTB amphibolite) exhibited similar mechanical behavior, much of which is neglected in conventional triaxial compression tests in which ${\sigma}_{2}$ = ${\sigma}_{3}$. Compressive rock failure took the form of a main shear fracture, or fault, steeply dipping in ${\sigma}_{3}$ direction with its strike aligned with ${\sigma}_{2}$ direction. Rock strength rose significantly with the magnitude of ${\sigma}_{2}$, suggesting that the commonly used Mohr-type failure criteria, which ignore the ${\sigma}_{2}$ effect, predict only the lower limit of rock strength for a given ${\sigma}_{3}$ level. The true triaxial failure criterion for each of the crystalline rocks can be expressed as the octahedral shear stress at failure as a function of the mean normal stress acting on the fault plane. It is found that the onset of dilatancy increases considerably for higher ${\sigma}_{2}$. Thus, ${\sigma}_{2}$ extends the elastic range for a given ${\sigma}_{3}$ and, hence, retards the onset of the failure process. SEM inspection of the micromechanics leading to specimen failure showed a multitude of stress-induced microcracks localized on both sides of the through-going fault. Microcracks gradually align themselves with the ${\sigma}_{1}$-${\sigma}_{2}$ plane as the magnitude of ${\sigma}_{2}$ is raised.