• Journal of KSNVE
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• v.7 no.4
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• pp.597-604
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• 1997

Ground vibrations induced from railroad were measured to get the basic data that can be usde to prepare countermeasures for solving environmental vibration problems. Vibration levels were measured simultaneously at three points in double distances from railroad. These data were analuzed with the kinds of trains, media to understand the magnitudes and characteristics of distance attenuation of railroad vibrations.

• Journal of KSNVE
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• v.8 no.4
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• pp.733-740
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• 1998

본 논문은 덕트 내에 설치된 음향 스크린의 특성을 연구하였다. 다양한 형상의 음향 스크린의 투과 손실 측정을 통하여, 음향 스크린에 의해 생긴 두 개의 비대칭 경로가 특정 주파수에서 큰 협대역 소음 저감을 발생시킴을 알 수 있었다. 그리고, 실험과 수치적 모의 실험을 바탕으로 이러한 현상을 정확하게 설명할 수 있는 해석적 모델을 개발하였다.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.509-515
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• 2002

Recently, the microprocessor with network function based control system instead of conventional microprocessor is widely used for industrial applications, and also these technologies are widely adopted for train control and monitoring in modem rapid transit system. The purpose of this paper is to propose a criteria for data transmission, which was designed and realized through Korea High Speed Train. Noise, distortion and attenuation are always present in data transmission system and strictly limit performance. This paper describes a method to calculate the propagation constant, attenuation constant, phase velocity and length of stub.

• Journal of Environmental Health Sciences
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• v.28 no.2
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• pp.1-9
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• 2002

This study was performed to investigate vibration generated from machines that were used at factories and construction works. Vibrations were measured at three points in a straight line based on distance from the vibration sources, and analyzed to assess the vibration bevels. The average vibration level of factory machines was 65.4dBV at 2m, and that of construction machines was 74.0dBV at 5m. Vibration attenuations was 4.0~8.2dBV by double distance. All such data were applied to gain coefficients of attenuation equations for predicting vibration level by distance from the vibration sources. Data recorded on tapes were analyzed to understand the characteristics of frequency because these characteristics are important factors to design a Plan for installing the vibration-Proof devices. Finally, considering results from these analysis, assessment, and prediction, the methods for reducing vibration generated from machines were discussed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.9
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• pp.816-821
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• 2010

The paper presents a theoretical analysis on the propagation characteristics of the high-frequency wave in an elastic waveguide whose diameter is less than or similar to the wavelength. The theoretical results were verified by comparing them with the numerical results obtained by the boundary-element method. The ratio of the waveguide diameter to the wavelength affects the number of the existing wavenumber, and thus it affects the propagation characteristics. In the media with attenuation, the trend is similar to that in the media without attenuation except the decreasing amplitude.

• Journal of KSNVE
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• v.9 no.5
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• pp.899-905
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• 1999

Construction equipment noise has caused much annoyance for a number of dwellers in nearby construction field and has become a very serious issure in our living environment. Therefore, in our country, a practical solution and a better method of reducing construction equipment noise are highly required in construction field. Practical solutions for the construction equipment noise, however, are very difficult because of the poorness of basic data and insufficiency of the existing research. Especially, in order to establish the sound insulation plan about pilling works noise with high sound pressure level and impactive, a real situation of sound characteristics about the noise of pilling works in foundation work demands more detail investigation. In this point, this study attempts to survey the characteristics of attenuation and propagation of construction equipment noise in pilling work using SIP(soil-cement injected precast pile) method with casing. And this study intends to get the basic data for establishment of a standard about construction noise.

• Journal of the Korean housing association
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• v.9 no.2
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• pp.67-78
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• 1998

Construction equipment noise has caused much annoyance for a number of dwellers in nearby construction field and it has become a very serious issue in our living environment. Therefore, in our country, a practical solution and a better method of reducing construction equipment noise are highly required in construction field. Practical solutions for the construction equipment noise, however, are very difficult to obtain, because of the lack of basic data and insufficient research works. Especially, in order to establish a successful sound isolation plan for piling work noise, which has high sound pressure level, the characteristics of the impact noise should be closely monitored and analyzed. This study attempts to survey the characteristics of attenuation and propagation of construction equipment noise in piling work by SIP(soilcement injected precast pile) method. In addition, this study intends to get the basic data to establish a standard about construction noise.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.227-236
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• 1997

Construction equipment noise has caused much annoyance for a number of dwellers in nearby construction field and has become a very serious issue in our living environment. Therefore, in our country, a practical solution and a better method of reducing construction equipment noise are highly required in construction field. Practical solutions for the construction equipment noise, however, are very difficult because the poorness of basic data and insufficiency of the existing research. Especially, in order to establishment of sound insulation plan about pilings work noise that has highly sound pressure level and impactive, a real situation of sound characteristics about pilings work noise in foundation work demands close investigation. In this point, this study attempts to surveys the characteristics of attenuation and propagation of construction equipment noise in pilings work using SIP(soilcement injected precast pile) method. And this study intends to get the basic data for establishment of a standard about construction noise.

• Journal of the Korean Society for Nondestructive Testing
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• v.14 no.1
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• pp.23-31
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• 1994

Sound scattering by cylindrical tubes submerged in water is numerically analyzed with material attenuation considered. Complex wave numbers is introduced to see the effects of material attenuation on resonance scattering Backscattering pressures from the shells immersed in water are calculated for air-filled aluminium and acryl tubes. In order to investigate the resonance characteristics in detail, numerical analysis program has been completed which enables us to evaluate the effects of material attenuation. The testing of the program by comparison with previous results is reported and calculation results are compared and discussed for both aluminium and acryl tubes with material attenuation considered. The resonance peak and width is strongly affected by attenuation and this becomes severe as the peak is sharp and narrow and $k_{1{\alpha}}$ is high.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.415-419
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• 2018

This paper predicts and measures the C/N ratio of a beacon signal transmitted from geostationary orbit satellite KorSat 5A ($113^{\circ}E$) at a ground station located in Kimpo. Based on the ground stations, we compared the rain attenuation of the zone K of ITU-R and the rain attenuation which analyzed the domestic weather information. In ITU-R, the Korean rainfall characteristics are classified into zone K, but forecasting the rainfall intensity and attenuation of three adjacent cities based on the cumulative rainfall data per minute from 2013 to 2017. The calculation of rainfall path and attenuation is based on ITU-R recommendations. The change of the C/N according to the rainfall amount was confirmed through the 2 week satellite beacon signal C/N measurement. The predicted critical C/N was decreased to 12 dB at $A_{0.3}$. During the experiment, it was confirmed that it decreased up to 8 dB according to the concentrated rainfall.