• Journal of Communications and Networks
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• v.17 no.1
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• pp.21-26
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• 2015

The general wiretap channel with noiseless feedback is first investigated by Ahlswede and Cai, where lower and upper bounds on the secrecy capacity are provided in their work. The upper bound is met with equality only in some special cases. In this paper, we study a special case of the general wiretap channel with noiseless feedback (called non-degraded wiretap channel with noiseless feedback). Inner and outer bounds on the capacity-equivocation region of this special model are provided. The outer bound is achievable if the main channel is more capable than the wiretap channel. The inner bound is constructed especially for the case that the wiretap channel is more capable than the main channel. The results of this paper are further explained via binary and Gaussian examples. Compared with the capacity results for the non-degraded wiretap channel, we find that the security is enhanced by using the noiseless feedback.

• Journal of the Korean Society of Industry Convergence
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• v.18 no.2
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• pp.90-98
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• 2015

This research propose with image-based visual a new approach to design a feedback control of mobile robot. because mobile robot must be recharged periodically, it is necessary to detect and move to docking station. Generally, laser scanner is used for detect of position of docking station. CCD Camera is also used for this purpose. In case of using camera, the position-based visual servoing method is widely used. But position-based visual servoing method requires the accurate calibration and it is hard and complex work. Another method using cameras is inmage-based visual feedback. Recently, image based visual feedback is widely used for robotic application. But it has a problem that cannot have linear trajectory in the 3-dimensional space. Because of this weak point, image-based visual servoing has a limit for real application. in case of 2-dimensional movement on the plane, it has also similar problem. In order to solve this problem, we point out the main reason of the problem of the resolved rate control method that has been generally used in the image-based visual servoing and we propose an image-based visual feedback method that can reduce the curved trajectory of mobile robot in th cartesian space.

• Land and Housing Review
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• v.9 no.1
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• pp.11-18
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• 2018

This study aims to empirically verify the impacts of job autonomy, job feedback and job manualization on the job satisfaction of the non-regular employees in a public corporation. For the empirical analysis, 163 non-regular employees(valid respondents) have been surveyed who are working in a public corporation. And the multiple regression analysis was used to statistically test the research hypotheses. The independent variables are 'job autonomy', 'job feedback', and 'job manualization'. The dependent variable is 'job satisfaction'. The results are as follows. The effects of 'job autonomy → job satisfaction(β=0.182, t=2.664, p<0.01)', 'job feedback → job satisfaction(β=0.208, t=2.927, p<0.01)' and 'job manualization → job satisfaction(β=0.397, t=5.785, p<0.01)' are all shown positive. Therefore, all the proposed hypotheses are accepted. From this result, we can get some lessons for the organizational management especially for the non-regular employees' job satisfaction. If you recognize that the non-regular workers are also valuable human resources for the company, it can be expected that strengthening the internal motivation of the employees through job enrichment such as autonomy, feedback, and manualization can positively influence the effectiveness of the organization.

• Journal of Electrical Engineering and Technology
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• v.12 no.6
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• pp.2378-2387
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• 2017

Violinists learn to make better sounds by hearing and evaluating their own playing though numerous practice. This study proposes a new method of auditory feedback, which mimics this violinists' step and verifies its efficiency using experiments. Making the desired sound quality of a violin is difficult without auditory feedback even though an expert violinist plays. An algorithm for controlling a robot arm of violin playing robot is determined based on correlations with bowing speed, bowing force, and sound point that determine the sound quality of a violin. The bowing speed is estimated by the control command of the robot arm, where the bowing force and the sound point are recognized by using a two-axis load cell and a photo interrupter, respectively. To improve the sound quality of a violin playing robot, the sounds information is obtained by auditory feedback system applied Short Time Fourier Transform (STFT) to the sounds from a violin. This study suggests Gaussian-Harmonic-Quality (GHQ) uses sounds' clarity, accuracy, and harmonic structure in order to decide sound quality, objectively. Through the experiments, the auditory feedback system improved the performance quality by the robot accordingly, changing the bowing speed, bowing force, and sound point and determining the quality of robot sounds by GHQ sound quality evaluation system.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1565-1577
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• 2016

For grid-connected LCL-filtered inverters, dual-loop current control with an inner-loop active damping (AD) based on capacitor current feedback is generally used for the sake of current quality. However, existing studies on capacitor current feedback AD with a control delay do not reveal the mathematical relation among the dual-loop stability, capacitor current feedback factor, delay time and LCL parameters. The robustness was not investigated through mathematical derivations. Thus, this paper aims to provide a systematic study of dual-loop current control in a digitally-controlled inverter. At first, the stable region of the inner-loop AD is derived. Then, the dual-loop stability and robustness are analyzed by mathematical derivations when the inner-loop AD is stable and unstable. Robust design principles for the inner-loop AD feedback factor and the outer-loop current controller are derived. Most importantly, ensuring the stability of the inner-loop AD is critical for achieving high robustness against a large grid impedance. Then, several improved approaches are proposed and synthesized. The limitations and benefits of all of the approaches are identified to help engineers apply capacitor current feedback AD in practice.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.7
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• pp.361-370
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• 2017

This paper proposes the architecture of test case generator that can generate test cases, considering feedback signals from subsystems controlled by an embedded system. In general, a closed system decides the next test input to its subsystem under its control referencing feedback signals from its subsystem. In such systems, it is hard to use the typical test cases generated without referencing feedback. The architecture proposed in this paper re-produces test cases in real time using feedback signals. The architecture is implemented and its effectiveness is verified through experimenting a demo system.

• Journal of KIISE:Information Networking
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• v.27 no.1
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• pp.58-67
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• 2000

The paper presents a representative-based feedback mechanism and rate adaptation policy for congestion control in multicast traffic for multimedia applications. In multicast congestion control, feedback implosion occurs as many receivers send feedback to a sender. We propose to use representatives to avoid the feedback implosion. In our scheme, receivers feedback packet loss information periodically and a sender adapts the sending rate based on the information collected through a hierarchy of representatives. A representative is selected in each region and roles as a filter to decrease the number of feedbacks. The simulation results show that the proposed scheme solves the feedback implosion problem and well adapts in a congested situation.

• Journal of Multimedia Information System
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• v.5 no.1
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• pp.59-62
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• 2018

The delay between input action and visual interface feedback ("Latency") in a touchscreen inking task reduces the user's performance. When the latency is less than 2.38ms, the user cannot perceive the latency in dragging task. This value is difficult to achieve on recent touchscreens and general purpose computers. So, methods of predicting touch points to reduce perceptible latency has been proposed. In general, touch points prediction is not perfect. When using point prediction, feedback of the predicted points is displayed on the screen, after a while, erased when the actual points are displayed. When this task is implemented by software, it causes additional latency to work to erase predicted points feedback. It therefore propose a platform for rendering point prediction feedback without additional latency by the FPGA. This platform transmits input points and HDMI signals rendering feedback of input points to the FPGA. The FPGA draws the feedback of points predicted based on the input points on the HDMI and displays the screen. Since hardware rendering changes the HDMI signal every frame, it does not require erasing work and rendering can be done within an early time regardless of the amount of rendering, so we will reduce the latency.

• Journal of International Academy of Physical Therapy Research
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• v.4 no.2
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• pp.552-556
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• 2013

The purpose of this study is to examine the effects of feedback breathing exercise on respiratory muscle activity. Thirty stroke patients were randomly and equally assigned to an experimental group and a control group. The experimental group received rehabilitation exercise treatment for 30 minutes and feedback respiratory exercise for 30 minutes and the control group received rehabilitation exercise treatment for 30 minutes and conducted motomed exercise for 30 minutes. All of them conducted exercises five times per week for four weeks. Respiratory muscles including the upper trapezius(UT), longissimus dorsi(LD), rectus abdominis(RA), external abdominal oblique(EAO) and, internal abdominal oblique(IAO) were measured using MP 150WSW prior to and after the experiment. Regarding pulmonary functions prior to and after the experiment, the experimental group showed significant differences in all sections but the control group did not show significant differences in any sections. As for in-between group differences after the experiment, there were significant differences in the UT, LD, RA, and IAO but no significant differences in the EAO. In conclusion, respiratory muscle activity was more effective for the experimental group than the control group. It is considered that feedback respiratory exercise may induce improvement in respiratory muscles in stroke patients through feedback breathing exercise.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.690-693
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• 2005

In this paper, a hybrid PD-servo state feedback control algorithm for swing up inverted pendulum system is proposed. It consists of two parts. The first part is the PD position control for swinging up the pendulum from the natural pendent position to around the upright position and the second part is the servo state feedback control for stabilizing the inverted pendulum in upright position. The first controller is PD controller and it is tuned to control the position of the pendulum by moving the cart back and forth until the pendulum swings up around the upright position. Then the second controller will be switched to stabilize the inverted pendulum in its upright position. The controller in this stage is the servo state feedback controller designed by pole placement. Experimental results of PD type swinging up control system, of stabilizing servo state feedback control system and of the proposed hybrid PD-servo state feedback control system to swing up and stabilize inverted pendulum show that the proposed method is effective and reliable for actual implementation while it is simple.