• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.563-563
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• 2013

Railway noise has been a social issues nowadays in our community. This paper discusses the environmental noise problem along railway lines. We overview the noise level and noise exposed populations due to conventional and high speed train operation at first. Then we introduce variety of noise reduction schemes to protect the community based on an engineering approach. Some applicationcases to reduce the noise will be demonstrated. Finally, we propose the noise barrier tunnel as a tool of a generic solution to reduce the community noise along railway lines.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6A
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• pp.611-621
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• 2010

When an enemy platforms transmit electronic jamming or tracking interference signal to a friendly ship's radar, the radar have to avoid the jamming and to track targets continually without losing the targets with the electronic protection techniques. Electronic protection is an essential key for a platform to survive in electronic warfare, for this purpose, jamming simulator was developed to provide electronic warfare environments for the test and evaluate the effectiveness of radar's electronic protection techniques. Jamming simulator has ability to generate a variety of deception and noise jamming signals using the DRFM which minimize phase distortions of 1GHz broadband radar signal with the phase sampling method. This paper presents the design contents of the jamming simulator to process the analysis of broadband radar signal and generate jamming signal, also proposes the algorithms of the deception and noise jamming and verifies the effectiveness of the simulator by field trial.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.241-245
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• 2003

This paper presents the LRB-based hybrid base isolation system employing additional semiactive control devices for seismic protection of cable-stayed bridges by examining the ASCE first generation benchmark problem for a cable-stayed bridge. In this study, ideal magnetorheological dampers (MRDs) are considered as additional semiactive control devices. Numerical simulation results show that the hybrid base isolation system is effective in reducing the structural responses of the benchmark cable-stayed bridge under the historical earthquakes considered. The simulation results also demonstrate that the hybrid base Isolation system employing semiactive MRDs is robust to the stiffness uncertainty of the structure. Therefore, the LRB-based hybrid base isolation system employing MRDs could be appropriate in real applications for full-scale civil infrastructures.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.208-215
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• 1999

Using the orthogonal arrays and the occupant analysis software based on the multi-body dynamics , two interactive design algorithms are proposed to improve the initial design of the occupant protection systems. Algorithm 1 sequentially moves the narrow design space within the upper and the lower design limit. Algorithm 2 sequentially reduces the relatively wide design space. Each design algorithm is composed of two levels . The first level is to improve the characteristics of the crash performance considering the noise factors. In order to obtain the robust design, the second level reduces the variations the noise factors. In order to obtain the robust design, the second level reduces the variations due to the tolerance of the design variable. To utilize the algorithm 1, HIC(Head Injury Criterion) , 3 msec criterion value of the chest acceleration and the femur load decreased by 27.4%, 10.4% and 55.8%, respectively. To utilizer the algorithm 2 , the results decreased by 38.0%, 10.5% and 3.0% , respectively.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.3 no.1
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• pp.21-35
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• 1995

Nowadays aviation noise significantly affects a number of people over the world. This paper is mainly focused on the effect of temporary and permanent hearing loss of cockpit crew, flight attendants, passengers, persons in communities exposed to aircraft overflight. Also this paper describes the human hearing mechanism and the processes of temporary and permanent hearing loss. The results of research are presented and the potential for hearing loss in aviation noise environments evaluated. The Occupational Safety and Health Administration (OSHA) hearing protection criteria are also addressed.

• Journal of Environmental Health Sciences
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• v.25 no.3
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• pp.94-102
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• 1999

To estimate the effects of environmental noise on inhabitants' life in an apartment area at Taejon, noise levels and traffic volume of major roads were measured. 203 housewives were surveyed by questionaires including general factors, noise related factors and three items of life effects: subjective evaluations on the general environment, annoyance, and life disturbance due to environmental noise. At the boundary adjacent to the road with more traffic volume, noise level was higher; according to the time, the amount of noise level was in the morning, in the evening, at noon, and at night in order. Most of boundary noise levels were higher than those of recommended standard environmental noise levels in a residential area. The boundary noise level showed a very significant linear relationship with traffic volume of near roads. Noise level difference in the apartments adjacent to three roads was ranged 2.4~6.7dB between in windows open and close state. The apartments adjacent to 9 lane or 6 lane-road, which were protected by noise prevention wall and 20m or more distance from the roads, showed higher noise level at middle floors and high floors than those of low floors; but the buildings adjacent to 4 lane-road, with no protection, showed higher noise level at low and middle floors than those of high floors. Among 203 housewives, 120(59.1%) participated in this study, and 86(73.2%) of them answered that the most serious environmental noise was traffic noise from near roads. Comparing traffic noise levels with those of before-migration, 67.0% participants found the environmental noise became louder. Fifty eight(49.5%) of the participants wanted noise protection wall and 15(25.9%) of them were willing to charge the fee. Less perception on the present noise comparing to those before-migration, less traffic volume, and lower noise levels in the apartments were related to higher scores of self-evaluation on the environment. Higher susceptibility on the present noise, areas with more traffic volume, higher boundary noise levels, and higher noise levels showed higher scores of annoyance on environmental noise and life disturbance. Considering above all things, it was suggested that traffic noise in this area was the major problem of environmental noise, and its' effect was so serious that inhabitants needed some preventive measures for better life quality.

• Journal of Radiation Protection and Research
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• v.24 no.3
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• pp.161-170
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• 1999

System performances in terms of image quality between an amorphous silicon DR system and a conventional film-screen system were evaluated. Various aspects of image quality MTF (modulation transfer function), NPS (noise power spectrum), SNR(signal-to-noise ratio) and contrast were measured and calculated. The MTF of the DR system was comparable to the film-screen systems. The noise was mainly dominated by the quantum mottle in both systems and the electronic noise was found in the DR system. The contrast of the DR system was better than the film-screen systems by virtue of high sensitivity and image processing. Compared to the film-screen systems in general radiography, the DR system had similar resolution and showed better contrast with the same exposure condition after contrast manipulation. The results of this study provide some useful information about the performance of the DR system in connection with medical applications.

• Journal of the Korea Society of Computer and Information
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• v.19 no.5
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• pp.37-42
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• 2014

The objective of this study is the frequency of the noise source 170 dB level of impulsive sound attenuation performance by earplugs to identify, to analyze the frequency characteristics of a shape and pattern. The attenuation performance of the impulsive noise by the frequency levels on the Combat Arm and 3M Form types 1100 Earplugs were evaluated. In order to check the sound attenuation performance of the B&K head and torso simulator and sound attenuation performance of the ear simulator data was verified. Previous studies have most impact, even in the noise source and the impulse noise level is 140 dB, but this study is higher than that of the impulsive noise source features. The results of the impulse noise attenuation effect is frequency-dependent mean 28.58 dB.

• Fire Protection Technology
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• s.18
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• pp.5-16
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• 1995

The capacity commonly required sensors includes capability of quickly and properly catching the conditions of a fire and discriminating other factors such as noise, interference, etc. IR flame detector which react to the infra-red rays emitted from the flame. This study is aimed to know the characteristic repond to the specified fire plate. Experiment is acted by manufacture's technical data that is explained relation of detective range and sensitivity.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.388-393
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• 1997

As the aircraft noise become the serious matter nowadays, registrations controlling the noise emission from aircraft are established to set up noise protection areas such as residential buildings and schools. Several methods are used to assess the noise impact of an airport on its surroundings. WECPNL is used as the aircraft legislation noise index in Korea and in Japan. In this paper, experiments were made to assess the total noise impact of Kwangju airport area by using WECPNL. Also restrictions related to buildings in this area and grants were reviewed to improve building attention in the inner zone.