• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.260-265
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• 2014

Recently, many active noise control (ANC) systems, which employ the adaptive filter controlling method, have been reported for eliminating unwanted noise. ANC systems based on the filtered-X least mean square (FXLMS) algorithm have a problem with compensating the acoustic feedback of secondary route. It is difficult to apply the real time, because transfer function of secondary route must be measured by off-line method to solve this problem. In this paper, we propose the ANC system that applies a correlation LMS(CLMS) algorithm for improving a problem of transfer function measurement. The proposed algorithm is based on input of road noise. The proposed ANC systems have an advantage of real-time process without degradation of performance, although there are many calculation compared with FXLMS algorithm.

• Journal of Sensor Science and Technology
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• v.29 no.6
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• pp.412-419
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• 2020

In this study, a PID control method for sweeping automatic linearization of a wavelength swept laser is proposed. First, the closedloop transfer function embodying the PID control is derived. Through the simulation of the function, K_p = 0.022, K_i = 0.008, K_d = 0.002 were obtained as the best PID coefficients for fast linear sweeping. The performance test using the PID coefficients showed that linear sweeping was held up well with a 98.7% decrement in nonlinearity after the 10th feedback, and 45 nm sweeping range, 1 kHz sweeping frequency, and 8.8 mW average optical power were obtained. The equipment consists of a fiber Bragg grating array, an optical-electronic conversion circuit, and a LabVIEW FPGA program. Every 5s, automatic feedback and PID control generate a new compensated waveform and produce a better linear sweeping than before. Compared with nonlinear sweeping, linear sweeping can reduce the cumbersome and time-consuming recalibration processes and produce more accurate measurement results.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1713-1715
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• 2007

Measurement of network traffic have shown that the self-similarity is a ubiquitous phenomenon spanning across diverse network environments. In previous work, we have explored the feasibility of exploiting the long-range correlation structure in a self-similar traffic for the congestion control. We have advanced the framework of the multiple time scale congestion control and showed its effectiveness at enhancing performance for the rate-based feedback control. Our contribution is threefold. First, we define a modular extension of the TCP-a function called with a simple interface-that applies to various flavours of the TCP-e.g., Tahoe, Reno, Vegas and show that it significantly improves performance. Second, we show that a multiple time scale TCP endows the underlying feedback control with proactivity by bridging the uncertainty gap associated with reactive controls which is exacerbated by the high delay-bandwidth product in broadband wide area networks. Third, we investigate the influence of the three traffic control dimensions-tracking ability, connection duration, and fairness-on performance.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.941-946
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• 2008

D&B method in tunnel construction requires accurate and rapid measurement of the ground movement, which of essential for feedback analysis. Recently, survey technique adapting IT is getting more and more emphasized in the field of construction and tunnel survey also follow the same trend. Case study and adaptability of IT technique for tunnel survey will be discussed in this study. The application of laserscannig method in the field of tunnel construction was reported in several advanced country including Austria and Japan. Survey for the crown and shoulder movements by IT survey method was conducted and the results were compared to those do the conventional method. The pipe-roof, grouting, ring-cut are installed in the this site to prevent expected large ground settlement. The result show that laserscanner system is prefered rather than conventional method in that better understanding for the displacement condition and origin condition was liable by the lasersacnnig method. IT survey solution makes if possible to execute more economic and safe construction.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.4
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• pp.684-693
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• 2011

Measurement time delay in the transfer alignment is very important. It has been well known that the time delay degrades the alignment performance and makes some navigation errors on the transfer alignment of slave INS(SINS). Therefore there are many schemes to eliminate that time delay but the compensation technique through the estimation by Kalman filter through modeling the time delay as a random constant is generally used. In the case of change over measurement time delay or the large measurement time delay, estimation performance in the existing compensation technique is degraded because model of time delay is not correct any more. In this paper, we propose the method to keep the time delay almost constant even though in the abnormal communication state and very small through feedback compensation using double buffer. Double buffer consists of two moving window to temporarily store measurements from master INS and slave INS in real time.

• The Journal of Korean Physical Therapy
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• v.14 no.1
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• pp.75-88
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• 2002

The purpose of this study was to investigate the influence of anterior, posterior, and lateral pelvic tilt exercise upon the gait characteristics of patients with hemiplegia including their gait velocity, cadence, stride length, step length of the non affected side, step length of the affected side, foot angle of the non affected side, foot angle of the affected side, base of support, and so on. The subject of this study was 24 men and women patients with hemiplegia. The patients, the subject of this study, were classified into 12 patients of treatment group applying pelvic tilt exercise using visual feedback and 12 patients of control group applying general pelvic tilt exercise, and then analyzed their gait before and after exercise. Temporal distance gait analysis (Boening, 1977) was used to analyze their gait, and ink foot-print was applied as on of measurement methods. To find out meaningful difference between control group and treatment group, this study carried out independent sample t-test for each item by utilizing SPSS/Win 10.0, compared changes in control group's and treatment group's gait characteristics before and after exercise as percentage, and applied paired t-test to conduct before-after test in same group. Statistical significance level was ${\alpha}$ < 0.05. The results of this study were as follows. As a result of independent sample t-test for control group's and treatment group's gait characteristics after exercise, it was not statistically significant so there was no meaningful difference between two groups. However, it was statistically significant in the change rate(%) of gait characteristics, and treatment group's patients with hemiplegia had been highly changed in gait characteristics in comparison with control group. From the above-mentioned results, could find that pelvic tilt exercise using visual feedback for patients with hemiplegia was effective to improve their gait ability and it could increase the ability in comparison with general pelvic tilt exercise. In the future, studies on the effect of pelvic tilt exercise using visual feedback shall be continued based on more quantitative methods.

• Smart Structures and Systems
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• v.3 no.2
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• pp.189-200
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• 2007

As a functional material, shape memory alloy (SMA) has attracted much attention and research effort to explore its unique properties and its applications in the past few decades. Some of its properties, in particular the electrical resistance (ER) based self-sensing property of SMA, have not been fully studied. Electrical resistance of an SMA wire varies during its phase transformation. This variation is an inherent property of the SMA wire, although it is highly nonlinear with hysteresis. The relationship between the displacement and the electrical resistance of an SMA wire is deterministic and repeatable to some degree, therefore enabling the self-sensing ability of the SMA. The potential of this self-sensing ability has not received sufficient exploration so far, and even the previous studies in literature lack generality. This paper concerns the utilization of the self-sensing property of a spring-biased Nickel-Titanium (Nitinol) SMA actuator for two applications: ER feedback position control of an SMA actuator without a position sensor, and estimation of the opening of a SMA actuated valve. The use of the self-sensing property eliminates the need for a position sensor, therefore reducing the cost and size of an SMA actuator assembly. Two experimental apparatuses are fabricated to facilitate the two proposed applications, respectively. Based on open-loop testing results, the curve fitting technique is used to represent the nonlinear relationships between the displacement and the electrical resistance of the two SMA wire actuators. Using the mathematical models of the two SMA actuators, respectively, a proportional plus derivative controller is designed for control of the SMA wire actuator using only electrical resistance feedback. Consequently, the opening of the SMA actuated valve can be estimated without using an extra sensor.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.10
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• pp.74-79
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• 2010

In this paper, a high gain W-band amplifier is presented using 70 run mHEMT MMIC technology. The length of source feedback line of common-source FET is carefully determined to maximize the gain at a design frequency. Simulation shows that MAG can be increased by 0.8 dB by optimizing the length of this line. In addition, this feedback line changes the input impedance of the common-source FET in a way that the input match can be made easier. In this work, 4-stage amplifier is designed on CPW using the source feedback. The measurement shows the excellent gain performance higher than 22.0 dB across 70~103 GHz.

• The Journal of Korean Physical Therapy
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• v.26 no.6
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• pp.442-448
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• 2014

Purpose: The objective of this study is to evaluate the effect of neuro-feedback training and transcutaneous electrical nerve stimulation (TENS) on stress, quantitative sensory threshold and pain in patients suffering from tension type headache. Methods: 22 participants who passed the preliminary evaluation were enrolled in the study and 11 participants were randomly assigned to each group. The control group (n=11) was subject to the TENS treatment of which was composed of a 20-minute session for 5 times a week during 4 weeks, and the experimental group (n=11) was subject to both neuro feedback training and TENS treatment for 10 minutes a day and 5 days a week during 4 weeks. The Perceived Stress Scale (PSS) was used to measure a level of stress and the quantitative sensory testing (QST) was used for the measurement of cold pain threshold (CPT) and heat pain threshold (HPT); A degree of pain was evaluated through the headache impact test-6 (HIT-6). Results: In comparision of all dependent variables between the control and subject groups, there were significant differences in stress, quantitative sensory threshold and pain after the treatment (p<0.05), and the experimental group showed significant differences in stress, CPT, HPT and pain (p<0.05) and the control group showed only a significant difference in HPT (p<0.05). Conclusion: Findings of this study demonstrate that the concomitant administration of the TENS treatment and neuro feedback training is effective on alleviation of stress, quantitative sensory threshold and pain in patients with tension type headache.

• Korean Medical Education Review
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• v.18 no.1
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• pp.38-43
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• 2016

The authors investigated the effect of feedback and remediation after formative assessment (FRFA) by comparing the FRFA score and that of summative assessment (SA) in a course on clinical skills. In March 2015, 33 subjects underwent evaluation of their ability to perform a complex clinical skill using a real-time ready-made mobile assessment form tool, and through e-mail they were supplied with their feedback and final score (the pass group earned 2 points; the intermediate group earned 1 point; the nonpass group earned 0 points) followed by their self-reflection. The nonpass group underwent a re-test and e-mail feedback again until they passed the test, given the ease of performance. In December 2015, the 33 subjects took a 10-item SA, and one of the 10 items addressed a similar clinical skill. The difference between the first score on the FRFA and the score on the SA was evaluated statistically (p=0.05) through data analysis, variance distribution, correlation analysis, and linear regression analysis using SPSS software ver. 16. The increase from the score on the SA to that on the FRFA was statistically significant ($4.5{\pm}9.29$) in the pass group and the intermediate group, and was $29.7{\pm}11.49$ in the nonpass group of the formative evaluation (p<0.001). Using an FRFA could decrease the range in the standard deviation of the score and increase the minimum score among the subjects.