• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.11a
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• pp.18-21
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• 2022

본 논문에서는 6 자유도 공간음향 렌더링 기술 관련 음향객체의 거리감 인지에 중요한 공기흡음 감쇠 효과 처리에 있어, 현장의 음원과 음향 센서 사이의 거리인 녹음거리에 해당하는 공기흡음 감쇠가 기본적으로 포함되어 3kHz 이상의 고주파 성분이 감쇠된 음원이 렌더링에 사용되는 문제점을 해결하는 방법을 제시한다. 이 방법에 의하면 6 자유도 공간음향 콘텐츠에 메타데이터로서 녹음거리 파라메터를 포함시키고, 렌더링할 때 공기흡음을 적용하기 위한 음원과 청취자의 거리값에 녹음거리에 대한 보상을 적용함으로써, 음원의 공기흡음 감쇠 효과를 정확하게 수정 적용하여 음원의 음색을 모든 거리에서 실제에 가깝도록 제공할 수 있게 된다. 특히, 원거리 녹음이 불가피한 비행기, 천둥, 폭발음 등 원거리 녹음음원의 음색에 녹음거리에 의한 음원의 공기흡음 감쇠가 적지 않은 영향을 미치게 되는데, 녹음거리의 적용에 의한 제안한 방법에 의해 음원과 청취자의 거리값에 대한 음원의 음색이 고주파영역의 녹음거리에 의한 원치 않는 감쇠를 보상하는 효과를 확인할 수 있었다.

• The Journal of the Korea Contents Association
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• v.13 no.8
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• pp.301-307
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• 2013

In the present study, space doses generated during X-ray radiography of hand, head, and abdomen, etc. were examined and whether the intensity of space doses of scattering rays is attenuated by the "inverse square law of distance" was figured out. First, the space doses of X-ray with small amounts of generated scattering rays such as hand radiography were mostly attenuated by the "inverse square law of distance" and were not detected at all at a distance of 2m. Second, the space doses of X-ray with large amounts of generated scattering rays such as head or abdomen radiography attenuated in higher rates than the rates under the "inverse square law of distance" at distances ranging from 30cm to 1m from the center of the irradiation field and were attenuated by the "inverse square law of distance" at distances ranging from 1m to 2m. Therefore, in X-ray rooms, the subject should be at least 2m away from the center of the irradiation field in the case of hand radiography and X-ray exposure prevention actions using protective devices are required in the entire spaces of the X-ray rooms in the case of head or abdomen radiography.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.04a
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• pp.27-31
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• 1999

진도의 거리에 따른 감쇠양상은 두가치 측면에서 중요하다. 첫째는 역사지진의 크기를 평가하는데 사용되고 둘째는 역사지진자료를 이용하여 지진위험도를 평가하는데 이용된다. 한반도의 경우 대부분의 지진활동 자료가 역사지진이므로 이지진들의 크기를 결정하고 이들을 이용하여 지진위험도를 평가하기 위하여 합리적인 진도감쇠양상의 결정은 매우 중요한 과제라 할수 있다 진도의 감쇠양상은 진앙진도와 진앙거리 등 두요소에 같이 의존함이 알려져 있으므로 한반도에서 MMI VIII만의 지진자료를 이용하여 결정된 Lee의 기존의 감쇠공식은 그 사용범위에 한계가 불가피하므로 상기 두 가지 요소를 함께 고려한 새로운 감쇠공식의 유도가 요구되어진다. 지체구조적으로 Sino-Korean 지괴라고 불리우는 중국 북동부와 한반도에서 발생한 MMI VIII-X 지진들의 자료를 이용하여 한반도에서 발생하는 MMI VIII-X의 강진들에 대한 새로운 진도감쇠양상을 결정하였다.

• Explosives and Blasting
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• v.19 no.1
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• pp.41-52
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• 2001

본 연구에서는 터널발파 진동의 전달 특성을 규명하기 위하여 네 곳의 도로터널의 '터널내부','터널외부','터널직상부 진행방향', '터널직상부' 진행직각방향'의 네 방향으로 발파진동을 계측하였다. 지발당장약량을 해당 지발당장약량과 최대 지발당장약량으로 구분하였으며, 지반의 진동 전달 특성을 확인하기 위하여 자승근 환산거리와 입방근 환산거리로 회귀분석 하였다. 또한 PPV, 거리별 우세진동수를 구하였다. 터널상부 진행방향의 진동 수준이 가장 크게 나타났으며, 진동의 감쇠도 크게 이루어졌다. 터널내부는 비교적 고주파성분이 우세하였으나 나머지는 일반적인 경향을 보였다 최대 지발당장약량을 적용한 입방근 환산거리의 경우가 거리별 감쇠특성 및 상관성이 다른 비교대상에 비하여 가장 우세하게 나타났다. 따라서 최대 지발당장약량을 적용한 입방근 환산거리 방식으로 설계하는 것이 바람직하다고 판단된다.

• Journal of the Korean Geophysical Society
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• v.5 no.3
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• pp.211-218
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• 2002

The reversed two station method (RSTM) devised by Chun et al. (1987) is widely used to obtain $Q_{Lg}^{-1}$ for Lg wave data with hypocentral distance greater than 90 km. By applying RSTM to the Lg data of central South Korea with hypocentral distance between 95 and 381 km, we obtained high $Q_{Lg}^{-1}$. The value of $Q_{Lg}^{-1}$ is very similar with that of southeastern S. Korea, which is derived from the same method for similar distances. The studied hypocentral range seems to distort $Q_{Lg}^{-1}$ to high value because decay rate in this range is higher than 0.5, which is typical decay rate of surface wave.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.4
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• pp.17-26
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• 2001

In order to estimate peak ground motions and frequency characteristics of strong ground motions in southern korea, we employed the stochastic simulation method with the moment magnitude(M$_{w}$) and the hypocentral distance(R). We estimated same input parameters that account for specific properties of source and propagation processes, and applied them to the stochastic simulation method. The stress drop($\Delta$$\sigma$) of 100-bar was estimated considering results of research in ENA, China, and southern korea. The attenuation parameter x was calculated by analyzing 57 seismograms recorded from September 1996 to October 1997 and the estimation result of the attenuation parameter x is 0.00112+0.000224 R where R is hypocenter distance. We estimated strong ground motion relations using the stochastic simulation method with suitable input parameters(e.g. $\Delta$$\sigma$, x, and so on). At last, we derived relations between hypocentral distances and ground motions(seismic attenuation equation) using results of the stochastic prediction.esults of the stochastic prediction.n.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.6
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• pp.59-70
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• 2003

We estimated the spectrum decay parameter $\chi$ and the stress parameter ($\Delta$$\sigma$) in southeastern Korea. Especially, we propose a procedure to compute site-independent $\chi$$_{q}$ and dependent $\chi$$_{s}$ values, separately, This procedure is to use the coda normalization method for the computation of site independent Q or corresponding $\chi$$_{q}$ value as the first step followed by the next step, the computation of $\chi$$_{s}$ values for each site using the given $\chi$$_{q}$ value evaluated at the first step, For the estimation of stress parameter, we used seismic data monitored from three earthquakes occurred near Gyeongju in 1999 with the method of Jo and Baag, In addition, we simulated strong ground motion using the $\chi$ value and the stress parameter, In this case, we calculated the $\chi$ value with conventional method. The $\chi$ value of 0.016+0.000157R and the stress parameter of 92-bar was applied to the stochastic simulation, At last, we derived seismic attenuation equation using results of the stochastic prediction, and compared these results with some others reported previously.ported previously.

• Explosives and Blasting
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• v.34 no.2
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• pp.1-9
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• 2016

In this study, the field tests were performed on V-cut, PLHBM 1 hole, PLHBM 2 hole in gneiss area in order to compare the effects of the vibration decay of a tunnel cut-hole according to the number of PLHBM holes with scaled distance. Based on the prediction equation of blasting vibration from the result of the tests, the decay rate of vibration were confirmed 21.8~61.1% using PLHBM 1 hole, 35.7~79.3% using PLHBM 2 hole for scaled distance within $10{\sim}100m/kg^{1/2}$ on the basis of V-cut PPV. As the scaled distance was increased, the effect of vibration decay was decreased. The effect of vibration decay of cut-hole for intial PLHBM 1~2 hole was significantly high.

• The Journal of the Acoustical Society of Korea
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• v.7 no.2
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• pp.20-25
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• 1988

This study is to explain the characteristic of excess attenuation on the ground through the outdoors experiment about noise propagation and the reduced model experiment of acoustic. The outdoors experiment on the attenuation of noise propagation was tried with the small engine that had large acoustic output, and then it was conformed that there was relationship between the excess attenuation calculated by measurement from distance attenuation and Log(D/(Hs+Hr)). As a result, it was found that the attenuation of noise propogation depended upon the direction of the wind and frequency and was regressed in a straight line. And the numerical values of excess attenuation on the ground could be calculated by regarding Log(D/(Hs+Hr)) as a parameter with an airing resistance $\sigma$. It was found that when the mean square error between the excess attenuation calculated by measurement and the value calculated by a fomula $L=-20Log\mid1+(r_1/r_2)Qexp(ik, \bigtriangleup r)\mid$ about optional $\sigma$ was least, the optimal decision of u was made. As the characteristic of model is the model experiment on a reduced scale of 1 to 40, It was conformed that it corresponds enough with the measurement value with measuring the distance attenuation in the large anecoic chamber.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.3
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• pp.263-271
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• 1996

The frequency band above 20GHz is the great radio resource which has not been used. But the attenuation by atmosphere is so large that the radio systems using this frequency band must have shorter hops. There are few studies of optimal hop length for these millimetric wave radio links in Korea. In this paper we analyzed the millimetric wave propagation characteristics in atmosphere and estimated rain attenuation which have a great effect on hop length. Furthermore, we present a rainfall rate(mm/h) of the cities including Seoul and Pusan using the data collected by several rainfall gauges. This paper presents a method of obtaining the optimum hop length for millimer wave radio links based on the rain rate date.