• 한국통신학회논문지
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• 제31권8A호
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• pp.798-803
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• 2006

다중사용자 다중입출력 시스템에서 채널 적응 기술을 사용하면 시스템의 통신용량을 증가시킬 수 있다. 하지만 이를 위해서는 많은 양의 사용자 채널품질 정보가 송신 단에 되돌림 되어야 한다. 다중사용자 다중입출력 시스템으로 기존에 제안된 per user unitary and rate control(PU2RC)는 사전코딩(preceding) 정보와 그때의 채널품질정보가 요구되며, 스케줄링의 효율이 떨어지는 단점이 있었다. 이러한 단점을 극복하기 위하여 본 논문에서는 되돌림 정보량 줄이는 새로운 방법을 제안한다. 제안된 기법은 미리 알려진 사전코딩행렬을 사용하고 사용자의 채널상황에 따라 선택적 되돌림(opportunistic feedback) 방법을 사용한다. 모의실험을 통하여 제안된 기법이 기존의 PU2RC 대비 훨씬 적은양의 되돌림 정보량으로 비슷한 통신용량 성능을 보장함을 보인다.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1627-1633
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• 2017

This paper proposes a voice enhancing ear-protection system which is based on feedback active noise control(FBANC). The proposed system selectively suppresses the background noise and preserves the talking voice by controlling the adaptive algorithm with the voice activity period detection module. The noise reduction performance of the proposed noise canceling algorithm is analytically derived for the two key performance affecting parameters, i.e., electro-acoustic coupling distance and noise bandwidth. The proposed system is also implemented with a floating-point DSP system and its performance is experimentally tested to compare with the analytically derived results. The achieved levels of noise reduction for the three different noise bandwidths cases, i.e., 10Hz, 50Hz, and 90Hz, are high to show 17.05dB, 10.54dB and 8.99dB, respectively. The feasibility of the proposed system is also shown by the peak noise reduction achieved more than 25dB while preserving the voice component in the frequency range between 200-800Hz.

• 한국소음진동공학회논문집
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• 제21권12호
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• pp.1104-1111
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• 2011

This paper investigates the filtered velocity feedback(FVF) controller for the reduction of the acoustic power radiated from a clamped beam. The instability problem due to the non-collocated sensor/actuator configuration when using PZT actuator should be sorted out. The roll-off property of the FVF controller at high frequency helps to alleviate the instability. The dynamics of clamped beams under forces and moments pair and the FVF controller are first formulated. The formulation of the sound radiated power is followed. The open loop transfer function(OLTF) synthesized with 100 modes is used to determine the stability of the control system. The control performance is finally estimated. The levels of the vibration and the sound radiated power are reduced in the wide bandbelow the tuning mode of the FVF controller.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.514-518
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• 2005

In this paper an adaptive fuzzy PI controller with feedback linearizing meth od is implemented to controlling flux and torque separately in induction motor. In this paper first decoupling of torque and flux which are outputs to be controlled, is achieved by using feedback linearization methodology. Then for reducing the effect of noise and rejection of disturbance, main part of controller which is adaptive PI fuzzy controller, is designed. Coefficients of PI controller are determined by defined fuzzy rules due to error dynamic. Inputs of fuzzy system are defined sliding surfaces which consist of torque and flux errors. The main contribution of this paper is effect reduction of noise and disturbance on torque and flux which is based on fuzzy logic and nonlinear control. At last the effectiveness of the proposed control scheme in presence of noise and load disturbance is simulated and comprised to applying sliding method. The results verify better effectiveness of the proposed method for effect reduction of noise and disturbance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권11호
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• pp.5304-5322
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• 2018

Since designing a feedback topology is a practical way to implement interference alignment at reduced cost of channel state information (CSI) feedback, six feedback topologies have been presented in prior works for a K-user multiple-input multiple-output interference channel. To fully reveal the potential benefits of the feedback topology in terms of the saving of CSI overhead, we propose a new feedback topology in this paper. By efficiently performing dimensionality-decreasing at the transmitter side and aligning interference signals at a subset of receivers, we show that the proposed feedback topology obtains substantial reduction of feedback cost over the existing six feedback designs under the same antenna configuration.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.464-473
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• 2006

This paper summarises theoretical and experimental work on the feedback control of sound radiation from honeycomb panels using piezoceramic actuators. It is motivated by the problem of sound transmission in aircraft, specifically the active control of trim panels. Trim panels are generally honeycomb structures designed to meet the design requirement of low weight and high stiffness. They are resiliently-mounted to the fuselage for the passive reduction of noise transmission. Local coupling of the closely-spaced sensor and actuator was observed experimentally and modelled using a single degree of freedom system. The effect of the local coupling was to roll-off the response between the actuator and sensor at high frequencies, so that a feedback control system can have high gain margins. Unfortunately, only relatively poor global performance is then achieved because of localisation of reduction around the actuator. This localisation prompts the investigation of a multichannel active control system. Globalised reduction was predicted using a model of 12 channel direct velocity feedback control. The multichannel system, however, does not appear to yield a significant improvement in the performance because of decreased gain margin.

• 대한물리의학회지
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• 제7권4호
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• pp.401-409
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• 2012

PURPOSE: The purpose of this study is to assess the difference in the effect of provision of feedback on knowledge of performance and knowledge of result in the training using somesthetic video game aimed at enhancement of balance of hemiparalysis patients due to stroke. METHODS: 20 stroke patients participated in the study. The participants were randomly divided into 2 groups, namely, the knowledge of performance feedback group (KP group, n=10) and the knowledge of result feedback group (KR group, n=10). Both groups received somesthetic video game training 5 times (30 minutes each) a week for total of 4 weeks. The KP group received feedback on the patterns of movement in execution of somesthetic video game. The KR group received feedback on the scores acquired following execution of somesthetic video game. Verification of the significance of the data was performed through paired t-test and independent t-test. RESULTS: Both groups displayed significant reduction in the movement of center of pressure (COP) and Timed up and Go (TUG), and significant increase in the Berg Balance Scale (BBS) following the training. Although the movement of COP was reduced for the KP group in comparison to the KR group, it was not statistically significant, and there was significant reduction in TUG and significant increase in BBS. CONCLUSION: The above results illustrate that provision of feedback on knowledge of performance is more effective than feedback on knowledge of result in somesthetic video game training for the purpose of enhancement of balance in stroke patients. Therefore, provision of feedback on knowledge of performance is necessary in somesthetic video game training for stroke patients.

• 보건의료산업학회지
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• 제6권2호
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• pp.111-119
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• 2012

The purpose of the study were to investigate the effect of the neuro-feedback program which improves brain function and stress reduction effect. The research design is one group pretest-posttest survey. 121 nursing students of a college in the Busan region took part in the study. Training involving the neuro-feedback program was conducted twice a week, 30 minutes per session, for a total of 10 weeks. The collected data was encoded and analyzed using SPSS 12.0 Version. The brain function and stress levels of the subjects were analyzed through the before-and-after results of the training were analyzed using a paired t-test. The results of the study showed that the BQ and SQ were enhanced as a result of the neuro-feedback. In particular, there were significant increases in the SRQ, ATQ, ACQ, and EQ of the BQ. SQ is correlated with the prevalence rate and resistance to disease, meaning not only psychological anxiety, uneasiness and excitement, but also physical anxiety and response to disease. Based on the study, by using the neuro-feedback training as a program for stress reduction, it is expected that nursing students will receive less stress from internal and external factors, and their ability to cope with stress will be enhanced.

• 전기학회논문지
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• 제56권11호
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• pp.2010-2016
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• 2007

PID control is windely used to control stable processes, However, its application to integrating processes is less common. In this paper, we proposed a stable PID controller tuning method for integrating processes with time delay using model reduction method. For proposed model reduction method, it disconnect an integrating factor from integrating processes and reduces separate process using reduction method. and it connect an integrating factor to reduced model. We can obtain stable integrating processes using P controller in inner feedback loop and PID tuning is then used to cancel the pole of the feedback loop. This guarantees both robustness and performance. Simulation examples are given to show the good performance of the proposed tuning method comparing with other methods.

• 한국환경교육학회지:환경교육
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• 제14권1호
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• pp.32-42
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• 2001

This study examined the effects of prompts, environmental alteration, and feedback on reduction of food wastes. The study was conducted at a student restaurant at a university. Subjects in this study were college students, faculty members and administrative staffs at the university. An A-BC-BCD-BC within subject design was employed. After baseline phase(A), prompts and environmental alteration were manipulated in the second phase(BC). In the next phase(BCD), feedback was added in addition to the prompts and environmental alteration. In the last phase(B), all the treatments except environmental alteration were withdrawn. The dependent variables n cluded (1) total weight of food waste per day, (2), the weight of food waster per person, (3) the ratio of food waste to total food served per day, (4) total amount of monetary value for food waste to total food served per day. The results indicated that prompts and environmental alteration were affective in reducing food wastes. Thus, measures of all the dependent variables decreased when environmental alteration and prompts were manupulated. However, when feedbacks were added to prompts and environmental alteration, the additional effect of feedback was not observed. The implications and limitations of these findings were discussed and the directions of future studies were also proposed.