• Journal of applied mathematics & informatics
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• v.41 no.6
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• pp.1257-1274
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• 2023

Rotating machines heavily rely on an intricate network of interconnected sub-components, with bearing failures accounting for a substantial proportion (40% to 90%) of all such failures. To address this issue, intelligent algorithms have been developed to evaluate vibrational signals and accurately detect faults, thereby reducing the reliance on expert knowledge and lowering maintenance costs. Within the field of machine learning, Artificial Immune Systems (AIS) have exhibited notable potential, with applications ranging from malware detection in computer systems to fault detection in bearings, which is the primary focus of this study. In pursuit of this objective, we propose a novel procedure for detecting novel instances of anomalies in varying operating conditions, utilizing only the signals derived from the healthy state of the analyzed machine. Our approach incorporates AIS augmented by Dynamic Time Warping (DTW). The experimental outcomes demonstrate that the AIS-DTW method yields a considerable improvement in anomaly detection rates (up to 53.83%) compared to the conventional AIS. In summary, our findings indicate that our method represents a significant advancement in enhancing the resilience of AIS-based novelty detection, thereby bolstering the reliability of rotating machines and reducing the need for expertise in bearing fault detection.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.639-644
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• 2002

Password typing is the most wifely ued identity verification method in computer security domain. However, due to its simplicity, it is vulnerable to imposter attacks Keystroke dynamics adds a shield to password. Discriminating imposters from owners is a novelty detection problem. Auto-Associative Multilayer Perceptron (AaMLP) has teen proved to be a good novelty detector. However, the wifely used 2-layer AaMLP cannot identify nonlinear boundaries, which can result in serious problems in computer security. In this paper, a nonlinear model, i.e. 4-layer AaMLP, is proposed to serve as the novelty detector, which can remedy the limitations of 2-layer AaMLP.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.05a
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• pp.1825-1831
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• 2006

본 논문에서는 반응 모델링에서의 집단 불균형을 해소하기 위한 이상탐지 기법의 활용을 제안한다. DMEF4 데이터셋의 카탈로그 발송 작업에 대하여 두 가지의 이상탐지 기법, one-class support vector machine (1-SVM)과 learning vector quantization for novelty detection (LVQ-ND)을 적용하여 이진분류기법들과 비교한다. 반응률이 낮은 경우에는 이상 탐지 기법들이 더 높은 정확도를 보인 반면, 반응률이 상대적으로 높은 경우에는 오분류 비용을 조정한 SVM 기법이 가장 좋은 성능을 보였다. 또한, 이상탐지 기법들은 발송비용이 낮은 경우에 높은 이익을 달성하였고, 발송비용이 높은 경우에는 SVM 모델이 가장 높은 이익을 달성하였다.

• Structural Engineering and Mechanics
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• v.77 no.2
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• pp.151-165
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• 2021

This paper aims to present a novelty damage detection method to identify damage locations by the simultaneous use of both the energy and displacement damage indices. Using this novelty method, the damaged location and even the damaged floor are accurately detected. As a first method, a combination of the instantaneous frequency energy index (EDI) and the structural acceleration responses are used. To evaluate the first method and also present a rapid assessment method, the Displacement Damage Index (DDI), which consists of the error reliability (β) and Normal Probability Density Function (NPDF) indices, are introduced. The innovation of this method is the simultaneous use of displacement-acceleration responses during one process, which is more effective in the rapid evaluation of damage patterns with velocity vectors. In order to evaluate the effectiveness of the proposed method, various damage scenarios of the ASCE benchmark problem, and the effects of measurement noise were studied numerically. Extensive analyses show that the rapid proposed method is capable of accurately detecting the location of sparse damages through the building. Finally, the proposed method was validated by experimental studies of a six-story steel building structure with single and multiple damage cases.

• IE interfaces
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• v.25 no.2
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• pp.170-177
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• 2012

Process control is essential to operate the semiconductor process efficiently. This paper consider fault classification of semiconductor based cyclic signal for process control. In general, process signal usually take the different pattern depending on some different cause of fault. If faults can be classified by cause of faults, it could improve the process control through a definite and rapid diagnosis. One of the most important thing is a finding definite diagnosis in fault classification, even-though it is classified several times. This paper proposes the method that one-class classifier classify fault causes as each classes. Hotelling T2 chart, kNNDD(k-Nearest Neighbor Data Description), Distance based Novelty Detection are used to perform the one-class classifier. PCA(Principal Component Analysis) is also used to reduce the data dimension because the length of process signal is too long generally. In experiment, it generates the data based real signal patterns from semiconductor process. The objective of this experiment is to compare between the proposed method and SVM(Support Vector Machine). Most of the experiments' results show that proposed method using Distance based Novelty Detection has a good performance in classification and diagnosis problems.

• IEMEK Journal of Embedded Systems and Applications
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• v.17 no.4
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• pp.239-247
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• 2022

The existing studies on the localization in the GNSS (Global Navigation Satellite System) denied environment usually exploit low-cost MEMS IMU (Micro Electro Mechanical Systems Inertial Measurement Unit) sensors to replace the GNSS signals. However, the navigation system still requires GNSS signals for the normal environment. This paper presents an integrated GNSS/INS (Inertial Navigation System) navigation system which combines GNSS and multiple IMU sensors using extended Kalman filter in partially GNSS-denied environments. The position and velocity of the INS and GNSS are used as the inputs to the integrated navigation system. The Mahalanobis distance is used for novelty detection to detect the outlier of GNSS measurements. When the abnormality is detected in GNSS signals, GNSS data is excluded from the fusion process. The performance of the proposed method is evaluated using MATLAB/Simulink. The simulation results show that the proposed algorithm can achieve a higher degree of positioning accuracy in the partially GNSS-denied environment.

• ETRI Journal
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• v.34 no.2
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• pp.288-291
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• 2012

In this letter, a new online anomaly detection approach for software systems is proposed. The novelty of the proposed approach is to apply a new semantic kernel function for a support vector machine (SVM) classifier to detect fault-suspicious execution paths at runtime in a reasonable amount of time. The kernel uses a new sequence matching algorithm to measure similarities among program execution paths in a customized feature space whose dimensions represent the largest common subpaths among the execution paths. To increase the precision of the SVM classifier, each common subpath is given weights according to its ability to discern executions as correct or anomalous. Experiment results show that compared with the known kernels, the proposed SVM kernel will improve the time overhead of online anomaly detection by up to 170%, while improving the precision of anomaly alerts by up to 140%.

• Journal of Mechanical Science and Technology
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• v.20 no.12
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• pp.2265-2283
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• 2006

There is tremendous interest of research which surrounds the concept of 'osteoporosis,' as shown by the intense and growing research activity in the field. The urgency to advance knowledge in this area is motivated by the need to understand not only the causes, diagnosis and treatment but also need for early identification or detection of this silent disease. Despite the various researches work is going on, important issues remain unresolved. In this paper, Osteoporosis has also been discussed with respect to biological, engineering, biochemical and physical aspects. The diagnostic and therapeutic techniques have been described for osteoporosis, for better health care. The novelty of the review paper lies in clarifying several myths, explaining the disease in details with biomedical engineering aspects and focuses on the several detection techniques, providing a new direction for early diagnosis of this deadly disease and gives new directions for the POCT device for Osteoporosis.

• Journal of Electrochemical Science and Technology
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• v.11 no.4
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• pp.421-429
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• 2020

This report describes the simultaneous detection of the two dyes most commonly used in food, tartrazine (TZ) and sunset yellow (SY), based on a microcomposite of carbon paste decorated with La₂O₃ and TiO₂. Anodic currents for SY-TZ were observed at 0.89-1.21 V by cyclic voltammetry (CV) separated with a ΔV of 0.32 V. The increased anodic peak currents compared to that of the unmodified carbon paste electrode were almost 50 and 41% for SY-TZ, respectively. The detection limits with the optimal amount of La₂O₃-TiO₂ were 0.02 and 0.03 µmol/L, respectively. The relative standard deviation (RSD) based on fifty measurements was less than 3%. The versatility and novelty of the sensor were tested with food samples containing these substances and other substances.

• Structural Engineering and Mechanics
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• v.81 no.5
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• pp.647-664
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• 2022

The powerful data mapping capability of computational deep learning methods has been recently explored in academic works to develop strategies for structural health monitoring through appropriate characterization of dynamic responses. In many cases, these studies concern laboratory prototypes and finite element models to validate the proposed methodologies. Therefore, the present work aims to investigate the capability of a deep learning algorithm called Sparse Autoencoder (SAE) specifically focused on detecting structural alterations in real-case studies. The idea is to characterize the dynamic responses via SAE models and, subsequently, to detect the onset of abnormal behavior through the Shewhart T control chart, calculated with SAE extracted features. The anomaly detection approach is exemplified using data from the Z24 bridge, a classical benchmark, and data from the continuous monitoring of the San Vittore bell-tower, Italy. In both cases, the influence of temperature is also evaluated. The proposed approach achieved good performance, detecting structural changes even under temperature variations.