• The Transactions of the Korean Institute of Power Electronics
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• 제5권6호
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• pp.584-591
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• 2000

Power Quality Compensator(PQC) has been installed to protect the sensitive loads against the voltage disturbances, such as voltage sag and interruption. In general, static switch is used for the purpose of link between utility and PQC. So transfer operation of the static switch play a important part in the PQC. Many studies on the structure and control of PQC have been progressed in active, but these researches have been rarely mentioned about any voltage-disturbances-detection method to start the PQC operation. In this paper, a new voltage-disturbances-detection algorithm for computer application loads using the CBEMA/ITIC curve is proposed for transfer operation of the static switch. The proposed detection algorithm is implemented to get fast detecting time through the comparison of instantaneous 3-phase voltage values transferred to DC values in the synchronous reference frame with the operating reference values. To get the robust characteristics against the noise, a first order digital filter is designed. The magnitude falling and phase delay caused by the filter are compensated through the error normalizing and numerical analysis using transfer function, respectively. Finally, the validity of the proposed algorithm is proved by ACSL simulation and experimental results.

• Transactions of the Korean Society of Mechanical Engineers
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• 제17권1호
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• pp.101-111
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• 1993

Many processes such as machining, injection-moulding and metal-forming are usually operated by hydraulic servo-systems. The dynamic characteristics of these systems are complex and highly non-linear and are often subjected to the uncertain external disturbances associated with the processes. Consequently, the conventional approach to the controller design for these systems may not guarantee accurate tracking control performance. An effective neuro-fuzzy controller is proposed to realize an accurate hydraulic servo-system regardless of the uncertainties and the external disturbances. For this purpose, first, we develop a simplified fuzzy logic controller which have multidimensional and unsymmetric membership functions. Secondly, we develop a neural network which consists of the parameters of the fuzzy logic controller. It is show that the neural network has both learning capability and linguistic representation capability. The proposed controller was implemented on a hydraulic servo-system. Feedback error learning architecture is adopted which uses the feedback error directly without passing through the dynamics or inverse transfer function of the hydraulic servo-system to train the neuro-fuzzy controller. A series of simulations was performed for the position-tracking control of the system subjected to external disturbances. The results of simulations show that regardless of inherent non-linearities and disturbances, an accuracy tracking-control performance is obtained using the proposed neuro-fuzzy controller.

• Journal of the Korean Vacuum Society
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• 제17권3호
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• pp.189-194
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• 2008

Measurements with a Langmuir probe, which are the most often used procedures of plasma diagnostics, can disturb plasma flows and change its characteristics quite a little because the probe should be inserted into thermal flowing plasmas. In this study, we calculated the characteristics of thermal plasmas with and without the probe into an atmospheric argon free-burning arc numerically, and investigated aerodynamic and thermal disturbances with temperature and axial velocity distributions. For the modelling of thermal plasmas, we have made two governing equations, which are on the thermal-flow and electromagnetic fields, coupled together with a commercial CFD package and user-coded subroutines. It was found that thermal disturbances happened to both sides of the probe, before and behind, seriously. Due to the aerodynamic disturbance, we could find that there were the stagnation point in front of the probe and the wake behind it. Therefore, aerodynamic and thermal disturbances caused by the probe insertion should be considered to increase the reliability of the probe diagnostics.

• Journal of the Society of Naval Architects of Korea
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• 제54권2호
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• pp.102-112
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• 2017

Many studies on dynamic positioning control algorithms using fixed feedback gains have been carried out to improve station keeping performance of dynamically positioned vessels. However, the control algorithms have disadvantages in that it can not cope with changes in environmental disturbances and response characteristics of vessels motion in real time. In this paper, the Fuzzy Gain Scheduling - PID(FGS - PID) control algorithm that can tune PID gains in real time was proposed. The FGS - PID controller that consists of fuzzy system and a PID controller uses weighted values of PID gains from fuzzy system and fixed PID gains from Ziegler - Nichols method to tune final PID gains in real time. Firstly, FGS - PID controller, control allocation algorithm, FPSO and environmental disturbances were modeled using Matlab/Simulink to evaluate station keeping performance of the proposed control algorithm. In addition, simulations that keep positions and a heading angle of vessel with wind, wave, current disturbances were carried out. From simulation results, the FGS - PID controller was confirmed to have better performances of keeping positions and a heading angle and consuming power than those of the PID controller. As a consequence, the proposed FGS - PID controller in this paper was validated to have more effectiveness to keep position and heading angle than that of PID controller.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• 제31권7호
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• pp.100-111
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• 2003

The HAUSAT-1(Hankuk Aviation University SATellite-1) will orbit at the altitude of 650km-800 km with 65 or 98 degree inclination angle. The effects of magnetic field and Earth gravity are more predominant than other space disturbances because the HAUSAT-1 will be positioned in LEO(Low Earth Orbit). The HAUSAT-1 design implements a magnetic control system and gravity-stable system which implement the solar panel deployment system. The simulation using MATLAB was performed to make sure the attitude stability of HAUSAT-1, which is based on the 8th order magnetic field model and non-linear equations of disturbances and the HAUSAT-1 attitude. The stability is investigated for two different HAUSAT-1 configurations and attitude which are affected by disturbances through simulation. The results for gravity-gradient stable and non gravity-gradient stable system are compared. Methodology of attitude stabilization was explored to develop an effective attitude control system for the HAUSAT-1 using magnetic torquers.

• Journal of the korean academy of Pediatric Dentistry
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• 제48권2호
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• pp.229-236
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• 2021

Eruption disturbances of the mandibular first molars can cause multiple problems in occlusal development although they are extremely rare. Early diagnosis and treatment are very important to prevent complications associated with eruption disturbances. The present case report describes the treatment of two cases of eruption disturbances of the mandibular first permanent molar. A fixed appliance composed of a cantilever spring with mandibular second deciduous molar as an anchor tooth was used to tract the impacted mandibular first permanent molar. The success of both cases shows that this novel traction appliance can be used to induce the eruption of an impacted mandibular first permanent molar within a short time in patients with intact mandibular second deciduous molar as an anchor tooth.

• Journal of The Korean Society of Integrative Medicine
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• 제9권2호
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• pp.43-52
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• 2021

Purpose : Chronic neck pain negatively impacts the quality of life and causes various problems in daily life due to pain, insomnia, and sleep disturbances in patients with this condition. Therapeutic interventions to solve these problems in rehabilitation and physical therapy are being introduced; however, the evidence of the efficacy of myofascial release (MFR) is still insufficient. This study aimed to investigate the effects of applying MFR on pain, insomnia, and sleep disturbances in patients with chronic neck pain. Methods : Ten patients with chronic neck pain were randomly selected and grouped into the experimental group (n₁ = 10) and control group (n₂ = 10) by cross-over design. Pain was measured before and after MFR intervention. Moreover, insomnia was measured only after MFR intervention. Polysomnography was performed after MFR intervention. Wilcoxon signed rank test and Mann-Whitney U test were used for the visual analog scale (VAS). Independent sample t-test was separately performed to measure insomnia and sleep. Results : After MFR intervention, the VAS score of the experimental group (p = 0.005) significantly decreased than that of the control group (p = 0.002). The insomnia score of the experimental group significantly decreased than that of the control group (p = 0.001). The total sleep time (p = 0.001), sleep efficiency (p = 0.001), and sleep latency (p = 0.001) of the experimental group significantly increased than those of the control group in the polysomnographic measurement. Conclusion : The application of MFR of the neck and upper trunk may have a positive effect on pain, insomnia, and sleep disturbances in patients with chronic neck pain. It was also suggested that an objective and quantitative polysomnography can be used more often in the field of rehabilitation and physical therapy.

• International Journal of Computer Science & Network Security
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• 제22권11호
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• pp.157-162
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• 2022

Cerebral palsy is one of the most serious forms of disorders of the psychophysical development of children, which manifests itself in disturbances of motor functions, which are often combined with speech disorders, other complications of the formation of higher mental functions, and often with a decrease in intelligence. The article will discuss the speech disorder in children with cerebral palsy. Emphasis is placed on some important aspects, which should bear in mind, investigating the problem of specifics of speech development of children with cerebral palsy. In particular at the heart of speech disorders in the cerebral palsy is not only damage to certain structures of the brain, but also the later formation or underdevelopment of those parts of the cerebral cortex, which are of major importance in linguistic and mental activity. This is an ontogenetically young region of the cerebral cortex, which is most rapidly developing after birth (premotor, frontal, temmono-temporal). It is important to take into account, that children with cerebral palsy have disturbances of phonemic perception. Often, children do not distinguish between hearing sounds, cannot repeat component rows, allocate sounds in words. At dysarthria, there are violations of pronunciation of vowel and consonant sounds, tempo of speech, modulation of voice, breathing, phonation, as well as asynchronous breathing, alignment and articulation. As a result, we identified the main features and specifics of the speech development of children with cerebral palsy and described the conditions necessary for the full development of language. Language disturbances in children's cerebral palsy depend on the localization and severity of brain damage. Great importance in the mechanism of speech disorders has a pathology that limits the ability of movement and knowledge of the world.

• Women's Health Nursing
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• 제28권4호
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• pp.296-306
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• 2022

Purpose: This study investigated the effects of peripheral neuropathy symptoms, self-care ability, and disturbances to daily life on quality of life (QoL) among gynecological cancer patients undergoing chemotherapy. Methods: The participants included 144 patients with gynecological cancer undergoing anticancer chemotherapy at a tertiary hospital in Seoul, South Korea, from December 1, 2021 to January 28, 2022. Convenience sampling was used to recruit patients who had received 4 or more cycles of chemotherapy using a paclitaxel-platinum regimen, and a self-reported questionnaire was used to collect data. Descriptive statistics, the t-test, analysis of variance, Scheffé test, Pearson correlation coefficients, and multiple regression analysis were performed. Results: Most of the participants had ovarian cancer (70.1%) or endometrial cancer (14.6%), and the most common number of treatment cycles was 6 to 10 (29.2%). The mean QoL (60.83±19.89) was greater than the midpoint. The regression model analyzing the patients' QoL was statistically significant (F=15.38, p<.001) with an explanatory power of 56.7%. Self-care ability (β=.39, p<.001), disturbances to daily life (β=-.38, p<.001), the duration of peripheral neuropathy symptoms (β=2.14, p=.034), and regular exercise (β=-2.12, p=.036) were found to significantly affect QoL. Conclusion: Efforts to improve the self-care ability of gynecological cancer patients who have experienced peripheral neuropathy after receiving chemotherapy and mitigate disturbances to their daily life can improve their QoL. Healthcare professionals should identify peripheral neuropathy symptoms and examine the effects of the symptoms on patients' daily lives. Improving the self-care ability of patients and alleviating their limitations in daily life may improve QoL.

• Transactions on Control, Automation and Systems Engineering
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• 제4권1호
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• pp.62-74
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• 2002

The tracking of a reference temperature trajectory in a polymerization batch reactor is a common problem and has critical importance because the quality control of a batch reactor is usually achieved by implementing the trajectory precisely. In this study, only energy balances around a reactor are considered as a design model for control synthesis, and material balances describing concentration variations of involved components are treated as unknown disturbances, of which the effects appear as time-varying parameters in the design model. For the synthesis of a tracking controller, a method combining the input-output linearization of a time-variant system with the parameter estimation is proposed. The parameter estimation method provides parameter estimates such that the estimated outputs asymptotically follow the measured outputs in a specified way. Since other unknown external disturbances or uncertainties can be lumped into existing parameters or considered as another separate parameters, the method is useful in practices exposed to diverse uncertainties and disturbances, and the designed controller becomes robust. And the design procedure and setting of tuning parameters are simple and clear due to the resulted linear design equations. The performances and the effectiveness of the proposed method are demonstrated via simulation studies.