• Physical Therapy Korea
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• v.23 no.3
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• pp.48-56
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• 2016

Background: Recently, there has been an emphasis on the use of interventions with biofeedback information for the maintenance or correction of posture. Objects: This study assessed the change of trunk posture and trunk muscle activation when people exhibiting postural kyphosis performed visual display terminal work with or without a contact feedback device (CFD). Methods: Eighteen right-handed individuals were recruited. Thoracic angle and right thoracic erector spinae (TES) muscle amplitude were analyzed. There were two sessions in these experiments. The control session involved 16 minutes of typing without a CFD, and the CFD session involved 16 minutes of typing with a CFD. The visual analog scale score was analyzed with a paired t-test, and the kinematic and electromyography data were analyzed through two-way repeated analysis of variance. Results: The paired t-tests revealed that subjects had significantly less pain after the CFD sessions than after the control sessions (p<.05). Significant main effects by session and by time were observed in the thoracic kyphosis angle (p<.05). There was a significant session${\times}$time interaction for TES amplitude (p<.05), along with significant main effects by session and by time (p<.05). Conclusion: The CFD caused people with postural kyphosis to straighten and to activate their TES continuously, even though they were habituated to bend their bodies forward. Therefore, the CFD was a beneficial treatment tool.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.37.2-37.2
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• 2016

There exist scaling relations that link the mass of supermassive black holes with both the velocity dispersion and the mass of the central stellar cusp of their host galaxies. This implies that galaxies co-evolve with their central black holes, potentially through the feedback from actively accreting supermassive black holes (AGN). We use integral field spectroscopy data from the 8.2m Gemini-North telescope to investigate ionized gas outflows in luminous local (z<0.1) Type 2 AGN. Our sample of 6 galaxies was selected based on their [OIII] dust-corrected luminosity (>$10^{42}erg/s$) and signatures of outflows in the [OIII] line profile of their SDSS spectra. These are arguably the best candidates to explore AGN feedback in action since they are < 1% of a large local type 2 AGN SDSS sample selected based on their [OIII] kinematics. Expanding on previously reported results concerning the kinematic decomposition and size determination of these outflows, here we report their photoionization properties and energetics. We find strong evidence that connect the extreme kinematics of the ionized gas with AGN photoionization. The kinematic component related to the AGN-driven outflow is clearly separated from other kinematic components, such as gravitation- or stellar-driven motions, on the velocity and velocity dispersion diagram. Our spatially resolved kinematic analysis reveals that up to 90% of the mass and kinetic energy of the outflow is contained within the central kiloparcec of the galaxy. The total mass and kinetic energy of the outflow correlate well with the AGN bolometric luminosity, resulting in energy conversion efficiencies between 0.01% and 1%. Intriguingly, we detect ubiquitous signs of ongoing circumnuclear star formation. Their small size, the centrally contained mass and energy, and the universally detected circumnuclear star formation cast doubts on the potency of these AGN-driven outflows as agents of negative feedback.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.7
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• pp.1734-1745
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• 1996

In this paper, a modified fixed-delay tree search with decision feedback(FDTS/DF) for compensation of non-linear distortion in digital magnetic recording channels is discussed. Since the nonlinear distortion, which becomes significant as recording density increases, is generally well modeled by the discrete Volterra series, the proposed equlizer is composed of a nolinear feedforward filter, a linear feedback filter, and a nonlinear distorton table, the values of which are determined by considering the effect of nonlinear distortion due to future data as well as the previous and current one. At the decision stage of FDTS, a path minimizing the branch metric is chosen by using the previously detected values, current predicted value, and future predicted value. We compare the performance of the linear FDTS/DF, the previous nonlinear FDTS/DF, and the proposed nonlinear FDTS/DF by computer simulation, and confirm that the proposed one chieves the best performance at high-density recording.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.2A
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• pp.183-190
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• 2008

The balanced Tx diversity with same data on two antennas can have better or lower performance than STBC Tx diversity, depending on the difference between each phase of two channels when the received signal is processed with MRRC. Therefore, using the feedback information based on the phase estimation in each channels, the better scheme of the balanced Tx diversity and STBC Tx diversity can be selected. However, when the phase condition changes during the transmission as the selected Tx. diversity scheme, the decoded bit can be erroneous because the previously estimated phase and newly estimated phase is different. In this case, the receiver should request the re-transmission of the just received signal to the transmitter part. Through computer simulation, it is shown that the combined scheme of the balanced Tx diversity and STBC Tx. diversity has better performance than STBC Tx diversity.

• Korean Journal of Child Studies
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• v.34 no.3
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• pp.1-19
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• 2013

The purpose of this study was to investigate the relationship between parents' behavior during picture-book reading and home literacy environment and their effects on toddlers' vocabulary. The subjects of the study were 46 toddlers and their parents. The MCDI-K(Im, 2002), Lee and Kim(2004)'s categories of Verbal Behaviors, the categories of Nonverbal Behavioral Analysis(Kim, 2005), and the Home Literacy Environment Index(Han, 2006) were used. The analysis of the collected data was guided by the research questions and involved the use of descriptive statistics, t-test and an analysis of relevant correlations. The results of this study were as follows; First, the toddlers' receptive vocabulary score was 1.2 times higher than the toddler's expressive vocabulary score. Second, the father's book reading behaviors and mother's book reading behaviors were quite similar, the most frequent types of behavior being the use of 'feedback', 'explanation', 'questioning' and 'pointing'. On the other hand, there was a significant difference between the reading behavior of the mother and father as regards the categories of 'linguistic attention ventilation', 'suggesting', 'directing(instructing)', 'expanding feedback', 'pointing' and 'gesture'. Mothers performed more of these behaviors than the fathers. Third, toddler's vocabulary scores were positively correlated with the mother's 'linguistic attention ventilation'. However, the mother's use of 'restriction' was negatively correlated with the toddler's vocabulary level. Toddler's vocabulary scores were positively correlated with the father's 'description', 'reasoning/predicting', 'questioning about function or action', 'demanding feedback' and 'pointing'. The toddler's vocabulary scores were also positively correlated with the relative abundance of home environment materials and the amount of time spent on parent-child home literacy activity.

• Journal of Communications and Networks
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• v.18 no.3
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• pp.387-396
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• 2016

Multiuser communication has been an important research area of underwater acoustic communications and networking. This paper studies the use of adaptive orthogonal frequency-division multiple access (OFDMA) in a downlink scenario, where a central node sends data to multiple distributed nodes simultaneously. In practical implementations, the instantaneous channel state information (CSI) cannot be perfectly known by the central node in time-varying underwater acoustic (UWA) channels, due to the long propagation delays resulting from the low sound speed. In this paper, we explore the CSI feedback for resource allocation. An adaptive power-bit loading algorithm is presented, which assigns subcarriers to different users and allocates power and bits to each subcarrier, aiming to minimize the bit error rate (BER) under power and throughput constraints. Simulation results show considerable performance gains due to adaptive subcarrier allocation and further improvement through power and bit loading, as compared to the non-adaptive interleave subcarrier allocation scheme. In a lake experiment, channel feedback reduction is implemented through subcarrier clustering and uniform quantization. Although the performance gains are not as large as expected, experiment results confirm that adaptive subcarrier allocation schemes based on delayed channel feedback or long term statistics outperform the interleave subcarrier allocation scheme.

• Journal of Digital Convergence
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• v.19 no.1
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• pp.51-58
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• 2021

The purpose of the study is to examine online grammar checkers and suggest when they could be used in English writing classes. The study was conducted in the second semester of 2019 at D University in Chungcheong-do, with a total of 35 first-year students participating in the study. For data collection, pre and post grammar tests, questionnaires, and learning journals were collected and analyzed. The results of this study are as follows. First, based on the results of the English grammar test, the online grammar checker was found to be effective in English writing class. Second, students judged whether accepting or not rather than accepting feedback provided by online grammar checker. Third, among the feedback provided by the online grammar checker, the order of (in)definite article, preposition, punctuation, verb number, and noun number were found. The several implications and limitations of this study are discussed.

• Journal of Engineering Education Research
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• v.25 no.6
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• pp.93-102
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• 2022

Due to COVID-19, all activities in society are emphasized non-face-to-face, and the educational environment is changing without exception. Looking at the results of the survey after conducting non-face-to-face education, there was a lot of rejection of non-face-to-face practical education. The biggest reason was that instructors were not familiar with the non-face-to-face education method, and feedback was not smooth during or after education. In particular, software practice education was not easy to share the software development environment, but communication and feedback on class contents and tasks were important. In particular, if face-to-face and non-face-to-face are alternately variable, it is not easy for practical education to be consistently connected. Even if non-face-to-face hands-on education is changed to face-to-face hands-on education, we will present a plan to use a data sharing system such as question-and-answer, assignment, practice content, and board content so that it can proceed smoothly. This study presents an efficient software education process that can provide learners with a software integrated practice environment based on a shared server, question-and-answer between instructors and learners, and share feedback on tasks. For the verification of the presented process, the effectiveness was confirmed through the survey results by applying the face-to-face/non-face-to-face education process to 220 trainees for 30 months in software education classes such as A university hands-on education, B company new employees, and ICT education courses.

• Journal of the Korean Society of Systems Engineering
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• v.10 no.1
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• pp.43-48
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• 2014

The door system for railway vehicles is the critical device directly influences on safety and satisfaction of passengers, Recently, electrical type of passenger door system is widely used for EMU type train instead of pneumatic type of passenger door system. The estimation of MTBF and failure rates for electrical type door system is essential. The manufacturor simply provides intrinsic reliability data for the railway operator. But actual reliability data based on operation and maintenance data is not complying with intrinsic reliability. In this study, operation and failure data associated with electrical door system were analyzed in order to determine actual MTBF and failure data. Intrinsic reliability data and service reliability data were studied to finallize much more practical and reliable actual reliability. Relax 2011 was used to predict intrinsic reliability and 217Plus model was also used to estimate of actual reliability data based on field data. Furthermore, it is necessary to keep studying on reliability prediction methodology and applying it in the field and doing research on improvement of reliability through feedback as well.

• Journal of Korean Society of Water and Wastewater
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• v.8 no.1
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• pp.9-17
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• 1994

The study of lake pollution problems is often related to the dynamic behavior of phosphorus. Several phosphorus models are available that may be suitable to study these problems. Depending on the the management objectives and data availability, some models may be more appropriate than others. Criteria are defined to help modelers choose the most appropriate total phosphorus models for different lakes. These criteria consider in-lake processes such as sediment feedback, stratification, and algal uptake and recycle.