• Journal of Korean Living Environment System
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• v.25 no.1
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• pp.90-97
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• 2018

The purpose of this study is to compare and analyze the air infections in middle and small hospitals with the facilities of large national hospitals that have air-borne infection isolation (AII) wards through actual condition investigation and airflow analysis simulation (CFD) and to provide basic data for prevention. The method and scope of the study are as follows. First, through literature review, data related to prevention of infection spread in domestic medical institutions were investigated. Second, we conducted a survey on the status of isolation facilities to prevent the spread of infectious diseases in large hospitals and small and medium - sized clinics in Korea. Third, airflow analysis simulation (CFD) was carried out using the isolation ward of the nationally designated inpatient ward and the data of the plane and facility system of the small clinic. As a result of the study, it is found that regulations applicable to small and medium-sized clinics are insufficient. In addition, the simulation results show that the infectious disease virus is likely to spread to other patients in the hospital.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.743-748
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• 2002

Chloride ingress into concrete followed by reinforcement corrosion and deterioration of concrete structures is a major problem for many structures under chloride attacks. Large-scale concrete structures directly exposed to seawater such as SeoHae Grand Bridge are increasingly constructed along the coast in Korea. It is necessary to investigate the environmental conditions of concrete structures exposed to chloride attacks. In this study, the air-borne chloride contents of highway bridges exposed to marine environment in Korea were measured.

• Journal of environmental and Sanitary engineering
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• v.17 no.3
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• pp.115-120
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• 2002

This study was performed on a questionnaire survey of 500 people about their awareness for indoor air pollution, and measured efficiency of air cleaner which can remove the CO and air-borne particulate of ETS(Environmental Tobacco Smoke) in air clean chamber. The room-size cleaner for measuring indoor air contaminants has been applied to evaluation of two different air cleaner such as the mechanic air cleaner with hepafilter(HPA) and the electrostatic air cleaner with metal plate. The measuring experiment was carried out in a chamber by sampling the air. The results obtained were as follows; As respondents are having their 90% of daytime indoors a day, and 38% of them can feel indoor air pollutions degrees directly by their sense of smell, For the installation of indoor pollution control equipment, 34% of all respondents installed air cleaner because of the problem of economical charge and almost respondents was not satisfied the trust of ability purified indoor air pollutants. In the experimental results, it was found that more than 95% of CD and air-borne particulate of ETS were removed within 20 minutes. The reaction kinetics of removal pollutants was verified as the pseudo-first order, Finally, it appeared that the room-sire air cleaner can be applied to new technology for removing indoor air contaminants.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.702-706
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• 2009

Internal running noise of a vehicle running in open field is the summation of air borne noise and structure-borne noise. In this paper vibration damping characteristics of carbody are investigated to see the effect of sound-deadening paint on the internal running noise. By using SEA method, vibration levels of complete train with and without sound-deadening paint are estimated and structure borne noise levels are estimated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.87-87
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• 2004

An air-conditioner has various noise sources such as a fan noise, a motor noise, and a vibration induced noise. To reduce these noise effectively, noise sources must be identified. Especially in this paper, the structure borne sound radiated from the motor bracket of the indoor air-conditioner is considered. To do this, the operational deflection shape, which is used for understanding of the behavior of the motor bracket at a particular frequency, is obtained and compared with the sound intensity, which is used for the noise identification. Through this study, the noise sources of indoor air-conditioner are defined and the effective noise reduction method is proposed.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.429-435
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• 2006

In this study multi-zone modeling program CONTAM 2.4 which is developed by NIST is used for modeling the air disinfection system which is consist of dilution, filtration, ultra violet germicidal irradiation (UVGI) for removing the indoor microorganism such as bacteria and fungus. Developed models those protect occupants against indoor microorganism generated in our daily life are enable to use for immune building simulation tool. Also, results indicate that those models are enable to compute the real situation that is almost impossible of carrying out experiment and identify the disinfection rate with highly reliance. Results also suggest that engineers will use these models as a design tool for the immune building system.

• 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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• 2003.05a
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• pp.797-801
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• 2003

The Statistical Energy Analysis is based on the power flow and the energy conservation between sub-systems, which enable the prediction of acoustic and structural vibration behavior in mid-high frequency ranges. This paper discusses the identification of SEA coupling loss factor parameters from experimental measurements of small reverberation chamber sound pressure levels and structural accelerations. As structural subsystems, steel plates with and without damping treatment are considered. Calculated CLFs were verified by both transmission loss values for air-borne CLF case and running SEA commercial software As a result, CLFs have shown a good agreement with those computed by software. Acoustical behavior of air-borne noise and structure-borne noise has been examined. which shows reasonable results, too.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.10
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• pp.758-765
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• 2002

KITECH and ODS performed a study of internal and external noise prediction of the Korean high speed prototype test train(HSR 350X). The object of this study was 3 kinds of cars, trailer car(TT2), motorized car(TMI ) and power car(TPI) and the predicted noise was for the two different driving speeds in free field and tunnel conditions. Data of carbody design and noise sources were delivered from manufactures. Some of noise sources which were not available in the project team, were chosen by experiences of ODS. Internal noise level of each car was predicted for two cases i.e, at 300 km/h and 350 km/h. In addition sound transmission path and dominant noise sources were also investigated for each section of the car, which is circular shell typed part of whole carbody. In case of TT2, the dominating sound transmission path is the (floor in terms of structure-borne noise and air-borne noise. The main noise sources are structure-borne noise from the yaw-damper and air-borne noise from the wheel/rail contact, whereas the dominating sound transmission path of TMI are floor and sidewall below the window in terms of structure-borne noise. The main noise sources of TMI are structure-borne noise from motor/gear unit and the yaw-damper in the free field, and air-borne noise from the wheel/rail contact and structure-borne noise from motor/gear unit in the tunnel. Through the external noise prediction for the KHST test train formation, the noise form the wheel/rail contact is estimated as one of the major sources. In addition, the noise specification of sub-component was proposed for managing each sub-surpplier to reach the KHST noise requirement. The specification provide the sound power of machinery part and transmission loss of component of carbody structure. The predicted noise level in each case exceeded the required limit. Through this study, the noise characteristics of the test train were investigated by simulation, and then the actual test will be performed in near future. Both measured and calculated data will be compared and further work for noise reduction will be continued.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.917-923
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• 2002

KITECH and ODS performed a study of internal and external noise prediction of the KHST test train. The object of this study was 3 kind of cars; trailer car(TT2), motorized car(TM1) and power car(TP1) and the predicted noise was calculated for the two different driving speeds in free field and tunnel conditions. Data of carbody design and noise sources were delivered from each manufactures. Some of noise sources which were not available in project team, were chosen by experiences of ODS. Internal noise level of each car were predicted for two cases i.e, at 300 km/h and 350 km/h. In addition sound transmission path and dominant noise sources were also investigated of each section of car, which is circular shell typed part of whole carbody. In case of TT2, the dominating sound transmission path is floor in terms or structure-borne noise and air-borne noise. The main noise sources are structure-borne noise from the yaw-damper and air-borne noise from the wheel/rail contact, whereas the dominating sound transmission path of TM1 are floor and sidewall below the window in terms of structure-borne noise. The main noise sources of TM1 are structure-borne noise from motor/gear unit and the yaw-damper in the free field, and air-borne noise from the wheel/rail contact and structure-borne noise from motor/gear unit in the tunnel. Through the external noise prediction for the KHST test train formation, the noise form the wheel/rail contact is estimated as one of the major sources. In addition, the noise specification of sub-component was proposed for managing each sub-surpplier to reach the KHST noise requirement. The specification provide the sound power of machinery part and transmission loss of component of carbody structure. The predicted noise level in each case exceeded the required limit. Through this study, the noise characteristics of the test train were investigated by simulation, and then the actual test will be performed in near future. Both measured and calculated data will be compared and further work for noise reduction will be continued.