• Journal of the Korean Home Economics Association
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• v.27 no.1
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• pp.85-96
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• 1989

The purpose of study was to survey the indoor noise of apartment houses, residents, attitudes and their adaptation behavior in order to offer the information helpful to apartment designers and residents, in their housing policy. Documentary research and questionnaire survey methods were used in this research. The sample was taken from 187 housewives living in apartments in Seoul. Data were analyzed with the SPSS program. The results were as follow : 1. It was found that apartment residents pointed out washing machine noise inside the home, piano and other musical instruments noise outside the home. 2. Piano and other musical instrument noise were heard at 3 to 6 pp.m. when residents heard the noise, and water supply and drainage noise in bathrooms were found most noisy. 3. Apartment residents were discontent with noise outside the home, and they displayed positive adaptation behavior at a reduced noise level. 4. Attitudes arising from indoor noise in apartment houses and human noise, water supply and drainage noise, doorway opening and closing noise were found to be significant in sampled apartment groups. 5. The youngest child's age was a significant variable on the residents' attitudes and adaptation behavior of indoor noise in apartment houses. 6. Between the resident' attitudes and adaptation behavior involving indoor noise in apartment houses. 6. Between the resident' attitueds and adaptation behavior involving indoor noise apartment houses, the more they became discontented, the more quickly they adapted in a postive manner.

• Journal of Biomedical Engineering Research
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• v.12 no.1
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• pp.35-42
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• 1991

In this paper, the information capacity, the intergrate performance measure of digital radiography system has been quantitatively analyzed. The effect of various factors affecting the information capacity of the digital radiography system in multistage detection processes has been considered and analyzed In detail. The results show that the more information capacity can be obtained with the smaller detector cell area, despite of the reduced signal to noise ratio due to the reduced number of X ray photons per detector cell. Considering the limit of human visual acuity, however. the sufficient resolution will be obtained when the detector cell size in $0.2{\times}0.2\textrm{mm}^2$ with 8 bit quantizaion. And also the results indicates that the information capacity may be severely reduced by the mixture of electric noise in final read-out stage.

• Journal of Biomedical Engineering Research
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• v.3 no.1
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• pp.49-50
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• 1982

In this paper, the information capacity, the intergrate performance measure of digital radiography system has been quantitatively analyzed. The effect of various factors affecting the information capacity of the digital radiography system in multi-stage detection processes has been considered and analyzed in detail. The results show that the more information capacity can be obtained with the smaller detector cell area, despite of the reduced signal to noise ratio due to the reduced number of X-ray photons per detector cell. Considering the limit of human visual acuity. however, the sufficient resolution will be obtained when the detector cell size in 0.2${\times}$0.2mm with 8 bit quantizaion. And also the results indicates that the information capacity may be severely reduced by the mixture of electric noise in final read-out stage.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.6
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• pp.420-425
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• 2015

In this paper a transfer matrix method is developed to solve for bending vibration of beam with linearly reduced width, and subsequently used to determine the exact natural frequencies for such problems. The differential equation, shear force, and bending moment are derived from Hamilton's principle, and the roots of the differential equation are computed using the power series solution of the Frobenius method. The effect of various taper ratio for bending vibration of beam with linearly reduced width is investigated in detail, and to validate the accuracy of the proposed method the results computed are compared with those given from commercial software(ANSYS).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.339-344
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• 2011

In the past much effort has been made to utilize advanced computational fluid dynamic (CFD) programs for aeroelastic simulations and analysis. However, it is limited in the field of unsteady aeroelasticity due to enormous size of computer memory and unreasonably long CPU time. Recently, AAEMS(Aerodynamics is Aeroelasticity minus Structure) was developed for linear time-invariant, coupled fluid-structure systems. In this paper, to demonstrate further the efficiency and accuracy of the new model reduction method, we successfully examine AGARD 445.6 wing modeled by FLUENT CFD, FSIPRO3D and NASTRAN FEM(Finite Element Method) programs. Using the ROM(Reduced Order Modeling) one can predict flutter boundary as a function of the dynamic pressure.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.647-650
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• 2004

The modeling of an active vibration isolation system is accomplished by using the equivalent spring constant, mass and rotational Inertia of each component. The detailed model of the actuation module is successful for describing its frequency-domain performance but also too complicated to implement it to actual system for control so that the order of the model is reduced up to the degree that preserves its characteristic in the low frequency range. The reduced model is suitable for identifying the unknown system parameters such as damping constants of components. The overall isolation system is described by using the reduced model of the actuation module. The accurate model ing and system parameter identification that is essential for the control of the active vibration isolation system is attained successfully.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.2
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• pp.200-207
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• 2009

Complex systems are made of many subsystems, those are developed and manufactured by many part companies. Even though the information for a part is necessary to analyze the performance of the other part, it is not so easy to get the information for that part from other companies due to many reasons like security or compatibilities. If the modal parameters of a system between the connecting points are available, we can reconstruct a reduced model for that system in a physical coordinate not in a generalized coordinate. The assemble of the equations of motion for the main system and the reduced equations of motion for the connected system can give a response of the main system considering the effects of connected systems. The results show that the proposed method can give the response of a system accurately. The rule for the selection of modes is to use the fundamental modes whose natural frequencies are low.

• The Journal of Korean Academic Society of Nursing Education
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• v.3 no.2
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• pp.150-162
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• 1997

The purpose of this study is to examine hospital noise level and discomfort due to noise. The subjects were 156 patients from University hospital in Taegu. The data was collected from April 10 to May 14, 1997. The collected data were analyzed by SPSS program using percentage, paired t-test, ANOVA, and Pearson Correlation Coefficient. The results were as follows ; The mean score of noise level was 1.62. There was no statistically significant difference in noise level between day and night. Patients perceived higher noise in the categories of conversation of visitors, conversation of care providers, noise of air conditioners, and the conversation of nearby patients than others during the day. Patients perceived higher noise in the categories of noise of air conditioners, conversation of visitors, conversation of care providers, and telephone ringing than others during the night. There were no statistically significant differences in noise level among the 4 wards during the day or night. Discomfort was due to the forementioned noise, categories of high scores were sleep disturbed, irritated, not so bad or not noisy, and noisy. To avoid noise, the subjects coped by putting on a quilt, going out, sleeping, opening or closing the window or door, and plugging ears. These results indicated that hospital noise have a negative influence on patients' health. So noise levels should be reduced in hospitals.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.7
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• pp.253-260
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• 2001

A Study of interior noise reduction in the magelv train is presented. Tarin speed of interest is low such that aero-dynamic noise is negligible and power supply system is a dominant noise source. Based on the measurements of interior noise and acceleration levels during running and zero speed conditions, dominant noise sources are identified. After spectra characteristics of noise sources are investigated several noise reducing methods are studied such as STL increasement of floor panels. sealing. and absorption treatment It is found that the most important noise sources are VVVF inverter and SLM in running condition, whereas air conditioner and DC/DC converter are dominant in zero speed. Sine the major noise sources are under the floor complete sealing and high STL of the floor panel are shown to be the most crucial factors in noise reduction After sound absorbing material, which is polyurethan foam of 50 mm thickness, is thickness, is attached to the downward side of the floor in addition to sealing treatment, the interior noise is reduced by 3~4 dB.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.6 s.111
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• pp.582-592
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• 2006

This paper presents experimental and analytic methods to reduce interior noise generated by car axle. The test vehicle has a whine noise problem at passenger seats. In order to identify transfer path of interior axle noise, the vibration path analysis, the modal analysis and running modal analysis are systematically employed. By using these various methods, it has been founded that the interior noise generated by car axle was air borne noise. To reduce and predict axle noise, various structural modifications are performed by using FEM and BEM techniques, respectively. Through the modification of the axle structure, the air borne noise of the axle was reduced 3$\sim$4 dBA level.