• The Transactions of the Korea Information Processing Society
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• v.13 no.3
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• pp.130-139
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• 2024

Artificial intelligence models are being used to detect facility anomalies using physics data such as vibration, current, and temperature for predictive maintenance in the manufacturing industry. Since the types of facility anomalies, such as facility defects and failures, anomaly detection methods using autoencoder-based unsupervised learning models have been mainly applied. Normal or abnormal facility conditions can be effectively classified using the reconstruction error of the autoencoder, but there is a limit to identifying facility anomalies specifically. When facility anomalies such as unbalance, misalignment, and looseness occur, the facility vibration frequency shows a pattern different from the normal state in a specific frequency range. This paper presents an N-segmentation anomaly detection method that performs anomaly detection by dividing the entire vibration frequency range into N regions. Experiments on nine kinds of anomaly data with different frequencies and amplitudes using vibration data from a compressor showed better performance when N-segmentation was applied. The proposed method helps materialize them after detecting facility anomalies.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.23 no.2
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• pp.8-14
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• 2023

The hepatic glycogen storage disease type 0 (GSD type 0) is an autosomal recessive disorder caused by a deficiency of hepatic glycogen synthase encoded by the glycogen synthase 2 (GYS2) gene, leading to abnormal synthesis glycogen. The clinical findings of GSD type 0 are hyperketotic hypoglycemia at fasting state and accompanying postprandial hyperglycemia and hyperlactatemia. GSD type 0 has only been reported in a very small number so far, and the diagnosis is likely to be missed because symptoms are mild, severe hypoglycemia is rare or asymptomatic, or symptoms gradually disappear with age. Essential management strategies include feeding high-protein meals to stimulate gluconeogenesis, frequent meals to prevent hypoglycemia during the day and feeding complex carbohydrates such as uncooked cornstarch to slowly release glucose during nignt. GSD type 0 has a good prognosis, with appropriate treatment, normal growth can be achieved and no complications occur. Significant hypoglycemia occurs less common in adulthood, but ongoing dietary management may be necessary.

• Journal of Aerospace System Engineering
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• v.18 no.4
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• pp.43-52
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• 2024

This paper presents an anomaly detection system that uses an LSTM-Autoencoder model to identify early-stage anomalies in the blade pitch system of floating wind turbines. The sensor data used in power plant monitoring systems is primarily composed of multivariate time-series data for each component. Comprising two unidirectional LSTM networks, the system skillfully uncovers long-term dependencies hidden within sequential time-series data. The autoencoder mechanism, learning solely from normal state data, effectively classifies abnormal states. Thus, by integrating these two networks, the system can proficiently detect anomalies. To confirm the effectiveness of the proposed framework, a real multivariate time-series dataset collected from a wind turbine model was employed. The LSTM-autoencoder model showed robust performance, achieving high classification accuracy.

• International Journal of High-Rise Buildings
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• v.9 no.2
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• pp.127-154
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• 2020

Disproportionate collapse triggered by local structural failure may cause huge casualties and economic losses, being one of the most critical civil engineering incidents. It is generally recognized that ensuring robustness of a structure, defined as its insensitivity to local failure, is the most acceptable and effective method to arrest disproportionate collapse. To date, the concept of robustness in its definition and quantification is still an issue of controversy. This paper presents a detailed review on about 50 quantitative measures of robustness for building structures, being classified into structural attribute-based and structural performance-based measures (deterministic and probabilistic). The definition of robustness is first described and distinguished from that of collapse resistance, vulnerability and redundancy. The review shows that deterministic measures predominate in quantifying structural robustness by comparing the structural responses of an intact and damaged structure. The attribute-based measures based on structural topology and stiffness are only applicable to elastic state of simple structural forms while the probabilistic measures receive growing interest by accounting for uncertainties in abnormal events, local failure, structural system and failure-induced consequences, which can be used for decision-making tools. There is still a lack of generalized quantifications of robustness, which should be derived based on the definition and design objectives and on the response of a structure to local damage as well as the associated consequences of collapse. Critical issues and recommendations for future design and research on quantification of robustness are provided from the views of column removal scenarios, types of structures, regularity of structural layouts, collapse modes, numerical methods, multiple hazards, degrees of robustness, partial damage of components, acceptable design criteria.

• Journal of the Korean Institute of Gas
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• v.1 no.1
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• pp.27-32
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• 1997

Continual monitoring of abnormal operating conditions i a key issue in maintaining high product quality and safe operation, since the undetected process abnormality may lead to the undesirable operations, finally producing low quality products, or breakdown of equipment. The statistical projection method recently highlighted has the advantage of easily building reference model with the historical measurement data in the statistically in-control state and not requiring any detailed mathematical model or knowledge-base of process. As the complexity of process increases, however, we have more measurement variables and recycle streams. This situation may not only result in the frequent occurrence of process Perturbation, but make it difficult to pinpoint trouble-making causes or at most assignable source unit due to the confusing candidates. Consequently, an ad hoc skill to monitor and diagnose in plat-wide scale is needed. In this paper, we propose a hierarchical plant-wide monitoring methodology based on hierarchical decomposition and principal component analysis for handling the complexity and interactions among process units. This have the effect of preventing special events in a specific sub-block from propagating to other sub-blocks or at least delaying the transfer of undesired state, and so make it possible to quickly detect and diagnose the process malfunctions. To prove the performance of the proposed methodology, we simulate the Tennessee Eastman benchmark process which is operated continuously with 41 measurement variables of five major units. Simulation results have shown that the proposed methodology offers a fast and reliable monitoring and diagnosis for a large scale chemical plant.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.4
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• pp.405-414
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• 2010

According to the statistics of SecurityFocus in 2008, client-side attacks through the Microsoft Internet Explorer have increased by more than 50%. In this paper, we have implemented a behavior-based malicious web page detection system and a blacklist-based malicious web page filtering system. To do this, we first efficiently collected the target URLs by constructing a crawling system. The malicious URL detection system, run on a specific server, visits and renders actively the collected web pages under virtual machine environment. To detect whether each web page is malicious or not, the system state changes of the virtual machine are checked after rendering the page. If abnormal state changes are detected, we conclude the rendered web page is malicious, and insert it into the blacklist of malicious web pages. The malicious URL filtering system, run on the web client machine, filters malicious web pages based on the blacklist when a user visits web sites. We have enhanced system performance by automatically handling message boxes at the time of ULR analysis on the detection system. Experimental results show that the game sites contain up to three times more malicious pages than the other sites, and many attacks incur a file creation and a registry key modification.

• The Journal of Society for e-Business Studies
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• v.23 no.2
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• pp.111-121
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• 2018

Many problems in rotating machinery such as aircraft engines, wind turbines and motors are caused by bearing defects. The abnormalities of the bearing can be detected by analyzing signal data such as vibration or noise, proper pre-processing through a few signal processing techniques is required to analyze their frequencies. In this paper, we introduce the condition monitoring method for diagnosing the failure of the rotating machines by analyzing the vibration signal of the bearing. From the collected signal data, the normal states are trained, and then normal or abnormal state data are classified based on the trained normal state. For preprocessing, a Hamming window is applied to eliminate leakage generated in this process, and the cepstrum analysis is performed to obtain the original signal of the signal data, called the formant. From the vibration data of the IMS bearing dataset, we have extracted 6 statistic indicators using the cepstral coefficients and showed that the application of the Mahalanobis distance classifier can monitor the bearing status and detect the failure in advance.

• Journal of Korean society of Dental Hygiene
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• v.9 no.4
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• pp.593-605
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• 2009

Objectives : In an aging society, as the necessity of the elderly oral health care was increased, the oral health dimensions was a lot more visible important to a community public health service for the quality of life improvement. In oral health care of the elderly, the periodic scaling treatment was required to manage periodontal tissue care. Methods : So, the 319 elderly people were selected by a random sampling method, those who are visitors of 5 public health centers in the South Jeolla Province. based on the findings of personal interview questionnaires and oral health states from these elderly subjects, we made a comparative analysis of oral health states of the elderly scaling program subjects. Results : 1. Among the participants, 52.4% of the elderly benefited from scaling care project otherwise 47.6%, the subjects with periodontal diseases were 78.4%, whereas 21.6% of the ones who don't. 2. In regard to perceptions of oral cavity abnormal symptoms, findings revealed that the teeth smart sensation with something cold was 'yes' 62.7%, 'No' 37.3%, gingival bleeding was 'yes' 61.4%, 'No' 38.6%, oral odor(halitosis) was 'yes' 63.3%, 'No' 36.7%, and dried mouth was 'yes' 63.3%, 'No' 36.7%. 3. The study data showed 73.2% of periodontal disease subjects, and 24.6% of no periodontal diseases responded that they have hyperesthesia and 67.6% of periodontal diseases, 39.1% no periodontal diseases responded that they have gingival bleeding. 4. In comparison of the presence of periodontal disease with scaling service program state, it is show that the elderly scaling service program was significant statistically in Elderly's periodontal disease prevention. according to analysis, 52.4% of the subjects with and 34.8% of no periodontal diseases received the Elderly scaling service program(p<0.05). Conclusions : Therefore, oral health care of the elderly, a community public health service the periodic scaling treatment was required to manage periodontal tissue care.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.4
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• pp.329-335
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• 2006

The aim of this study was to evaluate the relation between Asthenopia of near lateral phoria and fusional reserve and also to provide fundamental clinical data. A total of 97 subjects, aged between 17 and 35 years old, who had no strabismus, an eye trouble or whole body disease, were examined nacked visual acuity, corrected visual acuity, corrected diopter, phoria, fusional reserve tests from October of 2005 to July of 2006. We excluded 8 subjects for the following reasons: if they had an amblyopia affecting binocular vision or inaccurate data. After these exclusions, 87 subjects remained. The results were as follow. According to interview results was that in near works, exophoria and esophoria with asthenopia was 59.6%, 64.7%, and 52.6% respectively. The subjects who have exophoria of $0-6{\Delta}$ in the range of normal state was 19.1%. The subjects who have exophoria of $7{\Delta}$ over in the range of abnormal state was 80.9%. The fusional reserve was in inverse proportion to phoria. The fusional reserve was twice over of phoria were 30.3%, and twice under were 69.7%. The asthenopia complain persons were 33.9% with the twice over fusional reserve of phoria. The asthenopia no complain persons were 66.1% with the twice under fusional reserve of phoria. In conclusion, our research has shown conclusively that there is a link between asthenopia of lateral phoria and fusional reserve and we also find that fusional reserve must be examined when we prescribe for a patient who has phoria.

• Science of Emotion and Sensibility
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• v.10 no.3
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• pp.373-381
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• 2007

The purpose of this study was to extract important problem features for care of senile dementia patients. Selected cognitive ability test (Korean Mini-Mental State Examination: K-MMSE) and survey of basic & problem characteristics were conducted on 110 hospitalized senile dementia patients and 30 normal subjects. Problem features of senile dementia patients were extracted using factor analysis. The frequency difference of problem features due to the gender and dementia severities was verified using one-way ANOVA. Twenty problem features were extracted by the factor analysis. According to the gender, there are significant differences in the frequency of problem features in violent language & confabulation, collecting behavior, and repetitive behavior. According to the dementia severities, there are significant differences in the frequency of all problem features except abnormal sexual behavior and audio-visual disorder. The result of this study is expected to be used for the development of the senile dementia patients' life-care monitoring system.