• 한국전문물리치료학회지
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• 제23권3호
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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.

• 천문학회보
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• 제41권1호
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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.

• 한국통신학회논문지
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• 제21권7호
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• pp.1734-1745
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• 1996

본 논문에서는 디지탈 자기 기록 채널의 비선형 왜곡 보상을 위한 개선된 fixed-delay tree search with decision feedback(FDTS/DF)에 대하여 논한다. 고밀도로 갈수록 두드러지게 나타나는 비선형 왜곡은 일반적으로 이산 Volterra 급수로 잘 모델링되므로 비선형 feedforward 필터, 선형 궤환 필터, 그리고 비선형 왜곡 테이블에 의하여 등화기가 구성되며, 이 때 왜곡 테이블의 값은 미래의 기록 데이터에 의한 비선형 왜곡 영향을 고려하여 결성된다. FDTS를 사용한 결정단에서는 이전의 결정값, 현재의 추정치와 미래의 추정치를 고려하여 최소의 branch metric을 갖는 path가 선택된다. 모의 실험을 통하여 선형 FDTS/DF, 기존의 비선형 FDTS/DF, 그리고 제안된 비선형 FDTS/DF/DF의 성능이 비교되며, 제안된 비선형 FDTS/DF가 고밀도 기록시 가장 우수한 성능을 보임을 확인한다.

• 한국통신학회논문지
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• 제33권2A호
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• pp.183-190
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• 2008

본 논문에서 제안하는 결합 송신 다이버시티(The Combined Tx. Diversity) 방식은 이동통신 채널의 조건에 따라 기존의 2가지 송신 다이버시티 방식 중 채널 환경에 따라 더 우수한 송신 방식으로 전송을 하고, 또한 송신 방식이 바뀌는 조건에 따라 재전송 기술을 적용하여 더 우수한 성능을 발휘하는 송신 다이버시티 방식을 제안한다. 동일한 데이터를 2개의 송신 안테나로 전송하는 균등 송신 다이버시티 방식(Balanced Tx. Diversity; BTD)은 수신부에서 MRRC 방법(Maximal Ratio Receiver Combining)을 적용하여 수신할 때 2개의 각 채널의 "신호감쇄성분"과 "위상값들간의 차에 따른 여현값(Cosine Value)"에 따라 STBC 송신 다이버시티 방식보다 성능이 우수하기도 하고 열악하기도 하다. 따라서, 수신부에서는 추정한 2개의 각 채널의 환경을 토대로 송신부에 STBC 송신 다이버시티 방식과 BTD 방식 중 수신 성능을 더 좋게 할 수 있는 방식을 사용하도록 궤환 정보(Feedback Information)를 보내어 우수한 전송방식을 선택하게 하고, 추가적으로 제안하는 재전송 방식도 적용하여 기존의 STBC 송신 다이버시티 방식보다 우수한 전송 성능을 나타냄을 증명한다.

• 아동학회지
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• 제34권3호
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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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• 제18권3호
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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.

• 디지털융복합연구
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• 제19권1호
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• pp.51-58
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• 2021

본 논문은 온라인 문법체커에 대해서 살펴보고 영어쓰기에 있어서 온라인 문법체커 활용 시에 유의해야 할 점에 대해 제언을 하는데 목적이 있다. 본 연구는 충청도에 있는 D 대학교에서 2019년 2학기에 실시하였으며 총 35명의 대학교 1학년 학생이 참여하였다. 본 연구 자료 수집을 위해서 사전 · 사후의 문법 테스트와 설문지 그리고 학습저널이 수집되었고 분석되었다. 본 연구의 결과는 다음과 같다. 첫째, 영어문법 테스트 결과 온라인 문법체커는 영어쓰기수업에서 효과적인 것으로 나타났다. 둘째, 학생들은 온라인 문법체커에서 제공되는 피드백 무조건 받아들이기 보다는 스스로 판단하여 수용을 하거나 하지 않는 것으로 나타났다. 셋째, 온라인 문법체커에서 제공하는 피드백 중 (부정)관사, 전치사, 문장부호, 동사 수의 일치, 명사수의 일치 순으로 나타났다. 본 연구의 결과를 바탕으로 시사점과 제한점을 토론하였다.

• 공학교육연구
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• 제25권6호
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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.

• 시스템엔지니어링학술지
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• 제10권1호
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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.

• 상하수도학회지
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• 제8권1호
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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.