• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.759-763
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• 2006

The World Health Organization(WHO) has recommended population of sleep disturbance as one of the environmental health indicators. But the percentage of respondents who felt highly sleep disturbed, that is, %HSD can???thave application to sleep disturbance from instantaneous noise. Therefore, this study has been carried out to present the technique for assessing sleep disturbance on instantaneous noise quantitatively. The study of sleep disturbance on night time instantaneous railway noise has been undertaken. Noise monitor has been in operation from 22 hours to 7 hours during 6 nights at 12 locations. To assess instantaneous noise induced sleep disturbance, it was decided to measure body movement by actiwatch. %motility was used as indicators of sleep disturbance. %motility is the expected value of probability of motility value during 7 epochs (105s) of any noise event. The measures of instantaneous motility have been related to measures of instantaneous railway noise events. The relationship shows that %motility is a good predictor for assessing sleep disturbance and Korean is more sensitive to noise than European although the railway noise have been considered in this study. This study can be extended to assessing long-term sleep disturbance and give a guideline far policy decision.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.9
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• pp.960-966
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• 2009

The World Health Organization(WHO) has reported the sleep disturbance as one of the adverse effects of noise. And the effect of combined noise sources on human have been investigated because community noises are seldom heard and are concurrent. Therefore, the effects of combined noise source and its S/N ratio on sleep disturbance were investigated; as a single noise source, road traffic noise was selected, and construction and movie noise were combined with road traffic noise. Tests for sleep disturbance were conducted in bedrooms and the effect on each subjects' sleep was evaluated by questionnaire. The results showed that the rate of awakening increased slightly only when the SPL of construction noise was 10 dB higher than that of road traffic noise. It was also found that the sleep disturbance was affected by the type of combined noise sources and its S/N ratio.

• Journal of Environmental Health Sciences
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• v.30 no.3
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• pp.283-292
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• 2004

Valid evaluation of community reaction to road-traffic noise exposure is important for the policy making and quality of life. The purpose of this study is to evaluate the relationship between community reaction and nighttime road-traffic noise. The study measured nighttime roadside noise caused by high traffic which is greater than LAeq(22:00-07:00) 65dB(A) and lower than 65dB(A) at Chonju city, from March to April, 2003. Three hundred sixty seven subjects, aged from 20 to 65, were selected from those who are residing close to the major roads. They were asked to answer the questions regarding noise source, stress(PWI-SF), annoyance, disturbance of specific activity, disturbance of sleep, somatic symptom, and four suggested confounding factors. The relationship between annoyance, somatic symptom and noise exposure was not significant. Adjusted odds ratio(95% C.I.) for disturbance of communication　 and disturbance of attention and rest　 were 1.59(1.03-2.71), 1.64(1.06-2.81), respectively. On the other hand sleep disturbance　 was indicated as 1.34(0.77-2.32). The results suggested that federal policy-making about road-traffic noise should consider community reaction evaluated by various perspective including annoyance, disturbance of specific activity, disturbance of sleep, and confounding factors.

• The Journal of the Acoustical Society of Korea
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• v.37 no.6
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• pp.428-436
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• 2018

The response to noise may differ depending on the respondent's noise sensitivity. In this study, it was investigated that the noise sensitivity, the annoyance and disturbance of floor impact noise and opinions on their neighbors. The questionnaire respondents were divided into two or three groups based on noise sensitivity, and annoyance and disturbance on floor impact sound were compared. The noise sensitivity questionnaire method was presented. The questionnaire survey was conducted on 233 residents of Seoul, Gyeonggi - do area. As a result of the questionnaire survey, when the sensitivity group was divided into three groups, it was found that there was a significant difference between the groups with the noise sensitivity and the disturbance reaction. As a result of the opinions on their neighbors, positive responses to neighbors increased with age. Also, it was found that there was a low perception of inter - floor noise and life disturbance of the group having positive feelings about neighbors.

• Environmental Analysis Health and Toxicology
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• v.29
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• pp.6.1-6.6
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• 2014

Objectives Hospitalized patients are vulnerable to sleep disturbances because of environmental stresses including noise. While most previous studies on hospital noise and sleep have been performed for medical machines in intensive care units, there is a limited data for patients hospitalized in medical wardrooms. The purpose of present study was to measure noise level of medical wardrooms, identify patient-perceived sources of noise, and to examine the association between noise levels and sleep disturbances in hospitalized patients. Methods Noise dosimeters were used to measure noise level in 29 inpatient wardrooms at a university hospital. Sleep pattern and disturbance were assessed in 103 hospitalized patients, using the Pittsburgh Sleep Quality Index (PSQI) and Leeds Sleep Evaluation Questionnaire. Results The mean equivalent continuous noise level for 24 hours was 63.5 decibel A (dBA), which was far higher than 30 dBA recommended by the World Health Organization for hospital wardrooms. Other patients sharing a room were perceived as the most common source of noise by the patients, which was usually preventable. Of the patients in the study, 86% had bad sleep as assessed by the PSQI. The sleep disturbance was significantly correlated with increasing noise levels in a dose response manner. Conclusions Systemic organizational interventions are needed to keep wardrooms private and quiet to reduce sleep disturbance.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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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.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.443-448
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• 2000

In this paper, we propose a novel adaptive feedforward controller for periodic disturbance and noise cancellation, with a frequency tracking capability. It can be added to an existing feedback control system without altering the original closed-loop characteristics, which is based on adaptive algorithm. We introduce novel algorithm "Constrained AFC(adaptive feedforward controller) algorithm" that increase the convergence region regardless of the delay in the closed loop system. In the algorithms, coefficients of the controller are adapted using the residuals of constrained structure which are defined in such a way that the coefficients become time invariant. The proposed algorithm not only estimate the magnitude and phase of the tonal disturbance and noise but also track the frequency of the tone, which changes in quasi-static manner. The frequency tracking algorithm uses the instantaneous frequency approach based on Hilbert transform. A number of computer simulations have been carried out in order to demonstrate the effectiveness of proposed method under various conditions.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.11
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• pp.860-867
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• 2003

This paper presents a systematic method measuring a velocity disturbance to design the robust seek loop system of optical disk drives. The velocity disturbance caused by the rotation of a disk has a greater influence on the performance of the seek control loop as the rotational speed increases. Thus, it needs to measure the extent of the velocity disturbance and design the seek control loop based on the measured data. The measurement method of the velocity disturbance is a real-time . method using a measurable velocity and a velocity controller output and is a robust method considering actuator uncertainties. The loop gain adjustment algorithm is introduced to compensate for the actuator uncertainties. The proposed method is implemented by an experimental digital system and is evaluated through an experiment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.228-232
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• 2004

This paper is to identify the position of random disturbance on flexible dynamic system, and the position of the piezo ceramic actuator 0 minimize tip response. Correlation of the output signals from each parts on flexible system is used to identify the position of random disturbance. Except the correlation with an output signal from the position of random disturbance, other correlations have time delay. This is a base idea to identify the position on this study.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.1170-1175
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• 2003

Recently, the disturbance caused by an optical disk vibration and the external vibration/shock are more serious problem in an optical disk drives (ODD) as an ODD become small size and rotation speed increases. The conventional controller cannot cope with the mentioned problems properly when the disturbance and vibration are larger than some range. Therefore, we propose a new control scheme using a disturbance observer (DOB) and it can control the aforementioned problems. The designed the controller is applied to a commercial ODD in focusing direction, then its validity is proved by experimental method. By rising the disturbance observer theory, the focusing performance is conspicuously improved in the presence of sinusoidal vibrations or a shock disturbance. This algorithm also applies to a tracking structure also, because focusing structure is very similar to it.