• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.361-364
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• 2011

In this paper, This work demonstrates a experimental evaluation for vehicle road noise NVH performance from the component-level NVH measurements of Tire. The power unit noise from tire emitted by cars has been reduced. It has been found that tire noise dominates noise produced by the power train when vehicles are driven at high constant speed. Therefore tire pattern noise is affected by pattern and vehicle and transmission loss. Tire noise mechanism is generated by several mechanisms. The sound of tire can propagate either through the air or through the structure of vehicle. Pattern noise is the result of pressure variations through the air to the interior side of vehicle. Especially, smooth asphalt, the periodicity of tread design, groove depth is important factor, which have an influence on the reduction of tire pattern noise.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.2
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• pp.174-184
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• 2020

Objectives: The purpose of this study was to improve the working environment by identifying the work satisfaction of the cleaning workers of the aircraft and measuring and assessing the harmful factors of the cleaning process. Methods: We asked 23 cleaning companies for questionnaires and got 100 answers from 5 companies. The A-E Airline health manager has been contacted to establish a site survey schedule. The in-flight and lounge were measured using direct reading equipment. The harmful factor to be measured are noise, dust, temperature, volatile organic compound, total airborne bacteria, and total airborne bacteria. Results: Uncomfortable positions when replacing blanket, cleaning the table, and cleaning the floor have been identified as factor that reduce work satisfaction. Noise when replacing newspapers and cleaning toilets has been identified as a factor that lowers work satisfaction. Temperature and humidity were found to reduce work satisfaction during in-flight disinfection. Measurements of aircraft cabin and lounge with direct read equipment have shown that none of the items exceed the exposure criteria. Conclusions: As a result of measuring direct-reading equipment, no items exceeded the exposure criteria for each harmful factor. A clear survey of the working environment is required based on the results, and additional research is needed using personal sample measurement.

• Journal of Korean Public Health Nursing
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• v.9 no.2
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• pp.43-51
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• 1995

Many poeple has been engaged in industry is aware of the dangers from exposure to high intensity nose levels. The exposure to high intensity noise is encountered in a large number of situations. Laws governing the safety and health of employed people being to create a suitable working environment and eliminate unsafety practices and processes. Work areas should be designed and laid out so that they are satisfactory both from the environmental and safety points of view. In this connection safety also implies that noise is kept at a level which is not likety to cause hearing damage. This study was performed to measure the noise of press and assembly process in an automobile factory. and suggested the method of noise control. Consequently the effect ways of reducing level in working environment are as follows; 1. Changes to machines which would reduce noise generation. 2. Alteration of equipment to avoid impact in machinery and handing materials. 3. Enclosure of noisy machines or machine parts. 4. Mounting of attenuators on gas and air outlets as well as ventilation ducts. 5. Erection of sound absorbing screens. linings. and baffles in work areas. 6. The personal ear protectors can be chosen to protect the workers.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.563-564
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• 2014

Recent developments in the prediction of the contribution of windnoise to the interior SPL have opened a realm of new possibilities in terms of i) how the convective and acoustic sources terms can be identified, ii) how the interaction between the source terms and the side glass can be described and finally iii) how the transfer path from the sources to the interior of the vehicle can be modelled. This work discusses several simulation methods that can be used to represent the physical phenomena involved such as CFD, FEM, BEM, FE/SEA Coupled and SEA. This work focuses on the validation of the wind noise source characterization method and the vibro-acoustic models on which the wind noise sources are applied in the framework of a benchmark proposed by Hyundai Motors Corporation.

• Nuclear Engineering and Technology
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• v.53 no.4
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• pp.1088-1099
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• 2021

Time-frequency analysis technique is an effective analysis tool for non-stationary processes. In the field of reactor neutron noise, the time-frequency analysis method has not been thoroughly researched and widely used. This work has studied the time-frequency analysis of the reactor neutron noise experimental signals under bubble disturbance and control rod vibration. First, an experimental platform was established, and it could be employed to reactor neutron noise experiment and data acquisition. Secondly, two types of reactor neutron noise experiments were performed, and valid experimental data was obtained. Finally, time-frequency analysis was conducted on the experimental data, and effective analysis results were obtained in the low-frequency part. Through this work, it can be concluded that the time-frequency analysis technique can effectively investigate the core dynamics behavior and deepen the identification of the unstable core process.

• International Journal of Automotive Technology
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• v.8 no.1
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• pp.75-82
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• 2007

This paper presents practical work on the reduction of gear whine noise. In order to identify the source of the gear whine noise, transfer paths are searched and analyzed by operational deflection shape analysis and experimental modal analysis. It was found that gear whine noise has an air-borne noise path instead of structure-borne noise path. The main sources of air-borne noise were the two global modes caused by the resonance of an axle system. These modes created a vibro-acoustic noise problem. Vibro-acoustic noise can be reduced by controlling the vibration of the noise source. The vibration of noise source is controlled by the modification of structure to avoid the resonance or to reduce the excitation force. In the study, the excitation force of the axle system is attenuated by changing the tooth profile of the hypoid gear. The modification of the tooth profile yields a reduction of transmission error, which is correlated to the gear whine noise. Finally, whine noise is reduced by 10 dBA.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.311.2-311
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• 2002

Even through the problem of misalignment is of great importance, not much work has been reported in the literature on the effect of misalignment on the vibrations of the gear-bearing systems. Therefore, the nonlinear dynamic characteristics of the gear driving system due to misalignment are investigated in this work. Transmission error for helical gear and bearing nonlinear stiffness is calculated. (omitted)

• Korean journal of food and cookery science
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• v.11 no.5
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• pp.456-462
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• 1995

The work environment and 20 influencing variables in 20 conventional hospital foodservice systems were examined. Twenty hospitals with more than 500 beds in Seoul were surveyed to obtain data for study variables. The work environment index was measured by five objective measurements including noise (dB), light(Lux), temperature ($^{\circ}C$), humidity (％) and ventilation (mι/sec). Statistical methods used in this study were descriptive analysis and Pearson product moment correlation analysis. The number of beds, space of foodservice system, the proportion of dishwashing area space in foodservice system area, noise, humidity, and ventilation were significantly correlated to the work environment of the dishwashing area.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.122-123
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• 2019

Recently, road cutting works are frequently performed to repair aging underground utilities. However, the conventional road pavement cutting equipment in Korea generates a lot of noise and dust, and the development of high performance and eco-friendly equipment is required. This study classifies road cutting work and analyzes its work characteristics before improving road cutting machine. The classification and analysis results of this study will be used for the future productivity analysis and evaluation of road cutter developed.

• KIEAE Journal
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• v.2 no.1
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• pp.55-61
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• 2002

It seems inevitable for residential buildings to be high-rise and allocated near traffic roads due to the overcrowding in urban area. Acoustic environment in those residential buildings has been seriously deteriorated by the increase of traffic vehicles. Commonly used sound barriers have a limitation in controlling noise diffracted over the boundary of a sound barrier and hence are not effective to attenuate noise especially for the residential units in high level. The use of an enclosed noise barrier can be an alternative to supplement the defects of conventional noise barriers. The present work aims at providing useful data in designing enclosed noise barriers for residential areas adjacent to roads. Number of field measurements for various noise barriers and enclosed noise barriers were carried out and the results were discussed with relation to the proper design of enclosed noise barriers.