• Journal of Power Electronics
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• v.12 no.3
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• pp.477-486
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• 2012

This paper proposes a novel current control scheme for vector-controlled induction machine (IM) drives in the overmodulation (OVM) range, with which the voltage utilization of the voltage-source inverter (VSI) can be maximized. In the OVM region, the original voltage reference is modified by changing its magnitude and angle, which causes the motor current to be distorted, resulting in a deterioration of the current control performance. To meet with this situation, the harmonic components in the feedback currents should be eliminated before being input to the PI current controllers. For this, a composite observer is applied to extract the fundamental and harmonic components from the distorted currents, which gives a good performance without a delay and the effect of a fundamental frequency variation. In addition, through a detailed analysis of the response of the PI current controllers in the OVM range, the effectiveness of using the composite observer is demonstrated. Simulation and experimental results for a 3-kW induction motor drive are shown to verify the validity of the proposed method.

• Journal of the Korean Society for Railway
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• v.12 no.4
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• pp.557-564
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• 2009

This study compared KORAIL's procurement tasks with that of other companies. after analyzing the institutional and operational problems in procurement tasks especially in the respect of rolling stock and components which are KORAIL's major purchasing items, this study presented the way of purchasing cost Reduction through improving and streamlining procurement tasks.

• Geomechanics and Engineering
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• v.21 no.1
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• pp.85-93
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• 2020

In this article, the generalized thermoelastic theory with fractional derivative is presented to estimate the variation of temperature, the components of stress, the components of displacement and the changes in volume fraction field in two-dimensional porous media. Easily, the exact solutions in the Laplace domain are obtained. By using Laplace and Fourier transformations with the eigenvalues method, the physical quantities are obtained analytically. The numerical results for all the physical quantities considered are implemented and presented graphically. The results display that the present model with the fractional derivative is reduced to the Lord and Shulman (LS) and the classical dynamical coupled (CT) theories when the fractional parameter is equivalent to one and the delay time is equal to zero and respectively.

• Journal of Life Science
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• v.17 no.6 s.86
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• pp.867-872
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• 2007

The aging is related to numerous changes in our body system which declines functional ability. The functional ability in advanced age can be evaluated by the 4 components of fitness (cardiorespiratory endurance, muscular strength and endurance, flexibility and body composition). The understanding and knowledge of changing 4 components of fitness and the role of exercise on the process of aging is of paramount importance. Despite exercise and physical activity have been shown to delay the process of aging, the exercise guidelines and recommendations for old adults are not well published. This review is to presents the age-related changes in each component of fitness and to present current guidelines and recommendations for exercise in older adults.

• Journal of Power Electronics
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• v.19 no.4
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• pp.1045-1053
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• 2019

A symmetrical component decomposition scheme utilizing the characteristics of the asynchronous rotational reference frame transformation is proposed in this paper for the extraction of the positive and negative sequence components of distorted three-phase grid voltages. The undesired frequency component can be removed using a specially designed series coordinate transformation and half-cycle delays, where the delay can be controlled by adjusting the frequency of the rotating reference frame. The extracted symmetrical component can then be compensated based on the applied coordinated transformation. The dynamic response of the proposed algorithm is improved when compared to that of conventional methods. The effectiveness of the proposed algorithm is verified by simulation and experimental results.

• Molecules and Cells
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• v.42 no.6
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• pp.441-447
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• 2019

RAS gene mutations are frequently found in one third of human cancers. Affecting approximately 1 in 1,000 newborns, germline and somatic gain-of-function mutations in the components of RAS/mitogen-activated protein kinase (RAS/MAPK) pathway has been shown to cause developmental disorders, known as RASopathies. Since RAS-MAPK pathway plays essential roles in proliferation, differentiation and migration involving developmental processes, individuals with RASopathies show abnormalities in various organ systems including central nervous system. The frequently seen neurological defects are developmental delay, macrocephaly, seizures, neurocognitive deficits, and structural malformations. Some of the defects stemmed from dysregulation of molecular and cellular processes affecting early neurodevelopmental processes. In this review, we will discuss the implications of RAS-MAPK pathway components in neurodevelopmental processes and pathogenesis of RASopathies.

• Journal of Multimedia Information System
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• v.6 no.4
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• pp.239-244
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• 2019

With the development of Cyber-Physical Systems(CPS), several technologies such as automation control, automotive and intelligent house systems have been developed. To enable communication among various components of such systems, several wired and wireless communication protocols are used. The Controller Area Network(CAN) is one of such wired communication protocols that is popularly used for communication in automobiles and other machinery in the industry. In this paper, we designed and implemented a response time analysis system for CAN communication. The reliable data transfer among various electronic components in a significant time is crucial for the smooth operation of an electric vehicle. Therefore, this system is designed to conveniently analyze the response time of various electronic components of a CAN enabled system. The priority for transmission of the messages in the CAN bus is determined by the message identifier. As the number of nodes increases the transmission of low priority messages is delayed due to the existence of higher priority messages on the bus. We used Raspberry Pi3 and PiCAN2 board to simulate the data transfer for studying the comparative delay in low priority nodes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.8
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• pp.3946-3965
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• 2018

Network anomaly detection in Software Defined Networking, especially the detection of DDoS attack, has been given great attention in recent years. It is convenient to build the Traffic Matrix from a global view in SDN. However, the monitoring and management of high-volume feature-rich traffic in large networks brings significant challenges. In this paper, we propose a moving window Principal Components Analysis based anomaly detection and mitigation approach to map data onto a low-dimensional subspace and keep monitoring the network state in real-time. Once the anomaly is detected, the controller will install the defense flow table rules onto the corresponding data plane switches to mitigate the attack. Furthermore, we evaluate our approach with experiments. The Receiver Operating Characteristic curves show that our approach performs well in both detection probability and false alarm probability compared with the entropy-based approach. In addition, the mitigation effect is impressive that our approach can prevent most of the attacking traffic. At last, we evaluate the overhead of the system, including the detection delay and utilization of CPU, which is not excessive. Our anomaly detection approach is lightweight and effective.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.983-989
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• 2009

This study aims to systematically identify direct and indirect factors that influence labor productivity and to build a model that mathematically quantifies them so as to efficiently manage and increase labor productivity in the construction work. This study was performed based on the productivity model for workers in reinforced concrete construction projects, because it aims to establish a general construction labor productivity model that reflects many factors that influence labor productivity. Using statistical analysis, we found that the components that significantly influence productivity were the worker component, the work characteristic component, the work technique component, the work management component, the equipment & materials component, and the work guide component, while the work delay components did not significantly influence productivity. In addition, a priority analysis was performed based on the components that showed statistically significant effects. The results of the analysis indicated that the influence of work management component and the work technique component is more than that of the worker component and the work characteristic component. The construction labor productivity model that was formulated in this study could be used for the determining the standard productivity during the initial planning stage, so the best strategy for increasing labor productivity could be formulated.

• Journal of the Korean Society of Systems Engineering
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• v.20 no.spc1
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• pp.30-44
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• 2024

The DMAIC methodology, which is most familiar to battery production system developers, is partially inadequate in its conformity to utilize battery production system tasks, so it is necessary to improve the function and structure of the methodology, but many battery production system developers use the DMAIC method based on experience, causing side effects such as confusion, delay in tasks, and insufficient performance during tasks. Accordingly, we intend to conduct an empirical study to improve the "efficiency improvement and conformity evaluation method" so that the DMAIC methodology can be used more reasonably and easily. Using the three-stage research model, we derive components that affect conformity through literature and questionnaire surveys in the first stage, use relational characteristics between components in the second stage to confirm the effect on conformity, and use the relational characteristics in the third stage to confirm the possibility of improving efficiency by applying them to the DMAIC methodology in actual cases. Finally, the "Conformity Assessment Index (CAI) equation" based on relational characteristics is established to enable effective conformity evaluation and continuous improvement.