• Structural Monitoring and Maintenance
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• 제6권3호
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• pp.219-235
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• 2019

Scheduled inspections of common crossings are one of the main cost drivers of railway maintenance. Prognostics and health management (PHM) approach and modern monitoring means offer many possibilities in the optimization of inspections and maintenance. The present paper deals with data driven prognosis of the common crossing remaining useful life (RUL) that is based on an inertial monitoring system. The problem of scheduled inspections system for common crossings is outlined and analysed. The proposed analysis of inertial signals with the maximal overlap discrete wavelet packet transform (MODWPT) and Shannon entropy (SE) estimates enable to extract the spectral features. The relevant features for the acceleration components are selected with application of Lasso (Least absolute shrinkage and selection operator) regularization. The features are fused with time domain information about the longitudinal position of wheels impact and train velocities by multivariate regression. The fused structural health (SH) indicator has a significant correlation to the lifetime of crossing. The RUL prognosis is performed on the linear degradation stochastic model with recursive Bayesian update. Prognosis testing metrics show the promising results for common crossing inspection scheduling improvement.

• 지역사회간호학회지
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• 제30권2호
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• pp.161-173
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• 2019

Purpose: This study was conducted to develop and test a measurement of the suicidal protection(MSP) for high school students in Korea. Methods: Thirty-four preliminary items were initially developed based on literature review and focus group interviews. Those items were evaluated by experts for content validity with 31 items yielded. For testing validity and reliability of the measurement, data were collected from 330 high school students in Korea. Results: The item analysis selected 26 items. One item was deleted additionally through the primary exploratory factor analysis. The final exploratory factor analysis yielded 26 items in six factors such as fear of suicide, self-esteem, emotion regulation, support from others, support from family, and school life, explaining 66.6% of the total variance of the suicidal protection for high school students in Korea. Convergent validity and discriminant validity were supported by construct reliability, average variance extracted estimate, and standardized regression weight. MSP scores were positively associated with economic status, academic record and suicidal ideation. Also, criterion validity was supported through a significant correlation with the Reason for Living Inventory for Adolescent. The Cronbach's ${\alpha}$ reliability coefficient was .93 for the overall measurement and .72~.86 for the six factors. Conclusion: The results show that MSP may be valid and reliable for assessing suicidal protection of high school students.

• Journal of Microbiology and Biotechnology
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• 제29권5호
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• pp.731-738
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• 2019

Endophytic fungi are an important component of plant microbiota, and have the excellent capacity for producing a broad variety of bioactive metabolites. These bioactive metabolites not only affect the survival of the host plant, but also provide valuable lead compounds for novel drug discovery. In this study, forty-two endophytic filamentous fungi were isolated from Ficus elastica leaves, and further identified as seven individual taxa by ITS-rDNA sequencing. The antimicrobial activity of these endophytic fungi was evaluated against five pathogenic microorganisms. Two strains, Fes1711 (Penicillium funiculosum) and Fes1712 (Trichoderma harzianum), displayed broad-spectrum bioactivities. Our following study emphasizes the isolation, identification and bioactivity testing of chemical metabolites produced by T. harzianum Fes1712. Two new isocoumarin derivatives (1 and 2), together with three known compounds (3-5) were isolated, and their structures were elucidated using NMR and MS. Compounds 1 and 2 exhibited inhibitory activity against Escherichia coli. Our findings reveal that endophytic fungi from the rubber tree F. elastica leaves exhibit unique characteristics and are potential producers of novel natural bioactive products.

• Journal of Platform Technology
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• 제9권3호
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• pp.24-35
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• 2021

고속의 군용 항공기는 인명피해 최소화를 위해 생존 장비들과 경고 시스템으로 적의 위협 또는 내부 구성품 불량을 조종사가 파악하고 해결할 수 있어야 한다. 경고 전달은 디스플레이에 심볼 전시를 통한 시각적 방법과 통신 장비의 소리를 통한 청각적 방법으로 구분되는데, 청각적 방법이 반응 시간이 짧고 단순한 메시지 청취를 통해 조종사 혼란을 유발하지 않는다는 점에서 우월하다. 이에 본 논문은 군용 항공기용 음성/톤 경고 시스템의 효과적인 설계방법을 생명주기 관점에서 제시하고 평가하였다. 안전에 민감한 군용 항공기이므로 각 경고에 우선순위와 Inhibitible, Interruptible, Deactivatable의 세 가지 속성들을 적용하여 중대성과 긴급성을 반영했다. 그 결과 음성경고 재생까지 40ms가 소요되었으며, V모델 기반 개발 및 테스트를 통해 요구도를 모두 충족했고 제품 신뢰성이 향상됨을 확인하였다.

• Steel and Composite Structures
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• 제39권4호
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• pp.453-469
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• 2021

The cracking at the transverse diaphragm cutout is one of the most severe fatigue failures threatening orthotropic steel decks (OSDs), whose mechanisms and crack treatment techniques have not been fully studied. In this paper, full-scale experiments were first performed to investigate the fatigue performance of polished cutouts involving the effect of an artificial geometrical defect. Following this, comparative experimental testing for defective cutouts strengthened with carbon fiber-reinforced polymer (CFRP) was carried out. Numerical finite element analysis was also performed to verify and explain the experimental observations. Results show that the combinative effect of the wheel load and thermal residual stress constitutes the external driving force for the fatigue cracking of the cutout. Initial geometrical defects are confirmed as a critical factor affecting the fatigue cracking. The principal stress 6 mm away from the free edge of the cutout can be adopted as the nominal stress of the cutout during fatigue evaluation, and the fatigue resistance of polished cutouts is higher than Grade A in AASHTO specification. The bonded CFRP system is highly effective in extending the fatigue life of the defective cutouts. The present study provides some new insights into the fatigue evaluation and repair of OSDs.

• 신재생에너지
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• 제17권2호
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• pp.24-31
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• 2021

Renewable energy has become more popular with the increase in the use of solar power. Consequently, the disposal of defective and old solar panels is gradually increasing giving rise to a new problem. Furthermore, the efficiency and power output decreases with aging. Researchers worldwide are engaged in solving this problem by developing eco-module technologies that restore and reuse the solar panels according to the defect types rather than simple disposal. The eco-module technology not only solves the environmental problem, but also has economic advantages, such as extending the module life. Replacement of encapsulants contributes to a major portion of the module maintenance plan, as the degradation of encapsulants accounts for 60% of the problems found in modules over the past years. However, the current International Electrotechnical Commission (IEC) standard testing was designed for the commercialization of solar modules. As the problem caused by long-term use is not considered, this method is not suitable for the quality assurance evaluation of the eco-module. Therefore, to design a new accelerated test, this paper provides an overview of EVA degradation and comparison with the IEC and accelerated tests.

• 품질경영학회지
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• 제49권2호
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• pp.201-211
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• 2021

Purpose: This paper proposes a density adaptive grid algorithm for the k-NN regression model to reduce the computation time for large datasets without significant prediction accuracy loss. Methods: The proposed method utilizes the concept of the grid with centroid to reduce the number of reference data points so that the required computation time is much reduced. Since the grid generation process in this paper is based on quantiles of original variables, the proposed method can fully reflect the density information of the original reference data set. Results: Using five real-life datasets, the proposed k-NN regression model is compared with the original k-NN regression model. The results show that the proposed density adaptive grid-based k-NN regression model is superior to the original k-NN regression in terms of data reduction ratio and time efficiency ratio, and provides a similar prediction error if the appropriate number of grids is selected. Conclusion: The proposed density adaptive grid algorithm for the k-NN regression model is a simple and effective model which can help avoid a large loss of prediction accuracy with faster execution speed and fewer memory requirements during the testing phase.

• International Journal of Computer Science & Network Security
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• 제22권5호
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• pp.55-60
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• 2022

Acceleration of the pace of life, increasing the amount of information, the emergence of "clip way of thinking" as a phenomenon has led to the problem of choosing forms of presentation of educational materials to students. One of the ways to solve this problem is to use the means of visualization of information flow, forasmuch as the thinking of modern youth is more effective in perceiving visual images than verbal means. The purpose of the research is to prove the effectiveness of the use of visualization in the process of teaching Ukrainian as a foreign language to students with clip way of thinking. The following methods have been used, namely: analysis, synthesis, comparison, systematization and generalization of scientific literature; testing and surveys; pedagogical experiment; quantitative and qualitative analysis of data, interpretation and generalization of the research results. The essence of visualization means has been revealed; the expediency of their use in the methodology of teaching foreign students the Ukrainian language has been substantiated. It has been proven that the role of Ukrainian teachers lies in taking into account all new trends in teaching, integrating computer perception of information by foreign students into teaching technology and using cognitive visualization in order to intensify the learning process.

• 로봇학회논문지
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• 제17권3호
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• pp.264-272
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• 2022

Human-robot cooperative tasks are increasingly required in our daily life with the development of robotics and artificial intelligence technology. Interactive reinforcement learning strategies suggest that robots learn task by receiving feedback from an experienced human trainer during a training process. However, most of the previous studies on Interactive reinforcement learning have required an extra feedback input device such as a mouse or keyboard in addition to robot itself, and the scenario where a robot can interactively learn a task with human have been also limited to virtual environment. To solve these limitations, this paper studies training strategies of robot that learn table balancing tasks interactively using deep reinforcement learning with human's facial expression feedback. In the proposed system, the robot learns a cooperative table balancing task using Deep Q-Network (DQN), which is a deep reinforcement learning technique, with human facial emotion expression feedback. As a result of the experiment, the proposed system achieved a high optimal policy convergence rate of up to 83.3% in training and successful assumption rate of up to 91.6% in testing, showing improved performance compared to the model without human facial expression feedback.

• 대한유전성대사질환학회지
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• 제22권1호
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• pp.1-8
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• 2022

Long-chain fatty acid oxidation disorders (LC-FAOD) are an autosomal recessive inherited rare disease group that result in an acute metabolic crisis and chronic energy deficiency owing to the deficiency in an enzyme that converts long-chain fatty acids into energy. LC-FAOD includes carnitine palmitoyltransferase type 1 (CPT1), carnitine-acylcarnitine translocase (CACT), carnitine palmitoyltransferase type 2 (CPT2), very long-chain acyl-CoA dehydrogenase (VLCAD), long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD), and trifunctional protein (TFP) deficiencies. Common symptoms of LC-FAOD are hypoketotic hypoglycemia, cardiomyopathy, and myopathy. Depending on symptom onset, the disease can be divided as neonatal period, late infancy and early childhood, adolescence, or adult onset, but symptoms can appear at any time. The neonatal screening test (NBS) can be used to identify the characteristic plasma acylcarnitine profiles for each disease and confirmed by deficient enzyme analysis or molecular testing. Before introduction of NBS, the mortality rate of LC-FAOD was very high. With NBS implementation as routine neonatal care, the mortality rate was dramatically decreased, but severe symptoms such as rhabdomyolysis recur frequently and affect the quality of life. Triheptanoin (Dojolvi^®), the first drug for pediatric and adult patients with molecularly confirmed LC-FAOD, has recently been approved by the US Food and Drug Administration in 2020. In this review, the diagnosis of LC-FAOD and treatment including triheptanoin are summarized.