• 대한전자공학회논문지
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• 제27권12호
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• pp.1916-1924
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• 1990

In this paper attenuation effect on the measurement and the tomography of nonlinear parameter is discussed. We perform computer simulation with the method using harmonic components and the method using secondary wave components, and then estimate attenuation effect through the results and compare two measurement techniques. According to simulation result the attenuation effect is more intensive as large n and \ulcorner, and the degree of the attenuation effect is represented as error functions. In the aspect of measuremnet techniques, the method using secondary wave components is more insensitive to attenuation effect than the method using harmonic compnents. We obtain the same result in the nonlinear tomography, and show that the attenuation compensive filter is required because the whole tomogram is affected by frequency dependent attenuation(or nonlinear attenuation)

• 한국통신학회논문지
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• 제12권3호
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• pp.285-291
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• 1987

Seisimic wave가 지하 내부로 전파되어 갈 때 점차적으로 에너지를 상실함으로써 attenuation현상을 일으킨다. Seismic wave의 velocity를 complex number로 표시하여 실수부는 phase velocity, 허수부는 attenuation 상수로 하여 attenuation특성을 수치적으로 modeling하는 방법을 제시하였다. 이 방법은 주파수와 독립적으로 로그특성으로 감쇄해가는 매질 속에서의 파동의 전파를 modeling한다. 본 연구는 attenuation을 위치함수로 표시하여 순방향 및 역방향 numerical modeling에 응용하여 FFT계산때 발생하는 wrap-arround noise 를 효율적으로 제거함으로써 memory space를 절약하고 computing time을 감소시킬 수 있음을 잘 보여주고 있다.

• 한국정보통신학회논문지
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• 제6권7호
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• pp.1038-1043
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• 2002

The demand for multimedia service using Ka-band satellite communication are growing rapi이y. So, in this paper, we have analyzed rain attenuation with typical model, and proposed prediction model of rain attenuation in high frequency(over 20[GHz]). Path loss model by rain attenuation is based upon rain rate of representative region(6 cities). Proposed prediction model of rain attenuation and parameter of satellite link can be available for the Ka-band satellite communication.

• KIEE International Transactions on Electrophysics and Applications
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• 제4C권6호
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• pp.268-271
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• 2004

An analytic design formula is proposed for a TEM mode dielectric bandpass filter with attenuation poles at desired frequencies in the stop band. In order to sustain the constant ripple in the passband due to attenuation poles, the initial resonant frequencies of the various resonators adopted in a filter with attenuation poles are newly calculated. The proposed design theory is verified by designing various bandpass filters with attenuation poles in the stop band.

• 한국해양공학회지
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• 제27권1호
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• pp.16-23
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• 2013

By carrying out numerical analyses and model experiments, this paper presents the attenuation characterization of an L(0,2) guided ultrasonic wave propagating in a buried steel pipe. From this investigation, we first find that the L(0,2) mode has a better attenuation property. Second, it is shown from the numerical analyses that the attenuation increases with increases in the soil embedment length (0, 500, 1000, and 1500 mm) and degrees of saturation (0, 50, 99, and 100%). Third, it is also shown from the model experiment that the attenuation increases as the embedment lengths and soil moisture quantities (0, 10, 20, and 30 kg) increase. Finally, we find that an exponential extrapolation gives a better attenuation prediction because the extrapolation gives similar attenuation patterns between the numerical and experimental results.

• 한국지진공학회논문집
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• 제24권1호
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• pp.9-17
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• 2020

The stochastic point-source model has been widely used in generating artificial ground motions, which can be used to develop a ground motion prediction equation and to evaluate the seismic risk of structures. This model mainly consists of three different functions representing source, path, and site effects. The path effect is used to emulate decay in ground motion in accordance with distance from the source. In the stochastic point-source model, the path attenuation effect is taken into account by using the geometrical attenuation effect and the inelastic attenuation effect. The aim of this study is to develop accurate equations of ground motion attenuation in the Korean peninsula. In this study, attenuation was estimated and validated by using a stochastic point source model and observed ground motion recordings for the Korean peninsula.

• 전기학회논문지
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• 제64권9호
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• pp.1281-1287
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• 2015

We report the characteristics and differences of two types of attenuation measurement methods for electromagnetic partial discharge signal in GIS. The pulse method is to measure the attenuated waveforms in time domain and coverts them into frequency domain to get the attenuation spectra of given GIS section. This method simulates the real partial discharge signal. The frequency swept continuous wave method can obtain attenuation spectra directly so that it gives attenuation with low noise floor and simplicity. We show that both methods are effective and exchangeable because the attenuation results measured by two methods have similar trends

• 대한기계학회논문집
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• 제18권6호
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• pp.1535-1541
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• 1994

The void content of carbon fiber reinforced composite laminates was determined by the ultrasonic nondestructive technique. The ultrasonic immersion, through-transmission method developed stresses the utilization of spectral analysis and frequency dependence of the attenuation due to porosity. The measured attenuation shows approximately linear behavior over the frequency range investigated. The linear relationship between the void content and the attenuation slop (d $\alpha$/df) is found to hold, but the constant of proportionality is quite different for samples with different pore morphology. The void volume fraction determined by the attenuation slope agreed very well with that obtained by the acid digestion analysis.

• 한국항행학회논문지
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• 제10권4호
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• pp.356-363
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• 2006

본 논문에서는 위성통신을 이용한 방송 및 디지털 멀티미디어 서비스의 요구증대를 앞두고 20 GHz 이상의 높은 주파수 대역의 강우에 의한 전파 손실 예측 모델을 제안하고 강우량에 따른 감쇠 정도를 기존의 모델과 비교 분석 하였다. 본 논문에서는 Ka 대역에서 강우 감쇠 특성에서 이론치와 실험치가 접근함을 보이고 강우감쇠에 효과적인 기법을 제안하여 적응변조 시스템의 성능을 분석하였다. 제안 예측모델에서는 강우 강도를 기준으로 위성링크 설계를 위한 안테나 크기, 시스템의 불작동율 등에 대한 기본 자료를 Ka 대역 위성통신 시스템의 원활한 운영을 위해 제공한다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1998년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.44-51
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• 1998

A seismic attenuation formula is derived from the intensity maps of medium sized four earthquakes that occurred in the southern part of Korean peninsula. In order to obtain the seismic attenuation formula, the the coefficients of four attenuation equations representing the intensity maps are integrated using the proper weighting factors depending on the credibility of the data are assigned to. The proposed formula shows the trend of attenuation similar to the ones for the Eastern North America for the region within the epicentral distance of 200km, but produces higher attenuation at farther distances. Though the attenuation curve is not derived from the instrumental data, the result could be a useful tool for the analysis of seismic hazard in Korean peninsula.