Study of rain attenuation in Ka band for satellite communication in South Korea

Shrestha, S.,Choi, D.Y. Elsevier Science Ltd ; Pergamon 2016 Journal of Atmospheric and Solar-Terrestrial Physi Vol.148 No.-

<P>The important factor to be considered in the link budget estimation for satellite communication systems, operating at frequencies above 10 GHz is the rain attenuation. Scattering and absorption are the main concern for system designers at these frequency bands. This has resulted in the need for suitable prediction models that can best provide estimates of attenuation due to rain with available information of rain attenuation data. Researchers have developed models that can be used to estimate 1-min rainfall attenuation distribution for earth space link but there is still some confusion with regard to choosing the right model to predict attenuation for the location of interest. In this context, the existing prediction models need to be tested against the measured results. This paper presents studies on rain attenuation at 19.8 GHz, which specifies the performance parameters for Ka-Band under earth space communication system. It presents the experimental result of rain rates and rain-induced attenuation in 19.8 and 20.73 GHz for vertical and circular polarization respectively. The received signal data for rain attenuation and rain rate were collected at 10 s intervals over a three year periods from 2013 to 2015. The data highlights the impact of clear air variation and rain fade loss. Rain rate data was measured through OTT Parsivel. During the observation period, rain rates of about 50 mm/h and attenuation values of 11.6 dB for 0.01% of the time were noted. The experimental link was set up at Korea Radio Promotion Association, Mokdong, Seoul. Out of several models, this paper present discussion and comparison of ITU-R P.618-12, Unified Method, Dissanayake Allnutt and Haidara (DAH), Simple Attenuation (SAM), Crane Global and Ramachandran and Kumar models. The relative error margin of 27.51, 89.84,72.46% and 67.24, 130.84, 166.48% are obtained for 0.1%, 0.01% and 0.001% of the time for 19.8 and 20.73 GHz under vertical and circular polarization respectively from ITU-R P. 618-12 method which has been analyzed in the further section of this article. In order to obtain the better approximation of rain induced attenuation, the suitable method is proposed for earth space link whose efficiency have been compared with prominent rain attenuation models. The method provides useful information for system engineers and researchers in making a decision over the choice of suitable rain attenuation prediction method for earth space communication operating in the South Korea region. (C) 2016 Elsevier Ltd. All rights reserved.</P>

Different Characteristics of Radar Signal Attenuation Depending on Concrete Condition of Bare Bridge Deck

이지영,심재원,기성훈,이상염 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.7

This paper examined the attenuation method, which is used abroad, to derive a method to evaluate the condition of bare concrete bridge decks using ground penetrating radar (GPR) technology. For this purpose, 12 GPR surveys of 10 bridge decks in public service from the beginning of its service to 25 years of service were carried out to examine the attenuation characteristics of GPR signals under various concrete conditions. The survey revealed the signal below the top rebar of concrete bridge deck under the condition of using de-icing chlorides for snow removal was not clear. Therefore, using the receiving wave signal from top rebar was reasonable when attenuation of GPR signal was to be used for bridge deck evaluation. Examining the signal attenuation by the condition of concrete, dispersion of the attenuated signal was overall large in the initial performance period. However, since this is not due to deterioration, exclusion of the large dispersion from the evaluation of bridge deck condition was desirable. The attenuation size was linearly proportional to its two way travel time (signal transmission time), i.e., the depth of the top rebar, in a sound bridge deck. Also, the dispersion of the attenuation was small and symmetric to the linear regression line. If the bridge deck was maintained adequately, the linear regression correlation was also maintained similarly for the next several years. However, if deterioration occurred to be accompanied by increased attenuation and dispersion, correlation coefficient of the linear regression line declined. Nonetheless, the upper value of the attenuation representing sound concrete condition was still tended to be linearly proportional to two way travel time. Since the attenuation quantity could result in considerable debilitation just by the construction error, it is necessary to deal with the depth-error of top rebar for evaluating the concrete condition by using the GPR signal attenuation. Calibration was carried out by deriving a linear regression line for the signal two way travel time and the upper 90th percentile values of the attenuation obtained from the top bar position of the bridge and then removing it from the total attenuation.

PET-CT에서 감쇠보정 영상과 비감쇠보정 영상을 통한 Metal Artifact 보정에 대한 고찰

김준,김재일,이홍재,김진의,Kim, June,Kim, Jae-II,Lee, Hong-Jae,Kim, Jin-Eui 대한핵의학기술학회 2016 핵의학 기술 Vol.20 No.2

최근엔 대부분의 PET-CT영상의 감쇠보정은 많은 강점을 가지고 있는 CT를 기반으로 사용하고 있다. 하지만 CT 검사때 metal artifact가 발생하게 된다면, PET 영상에서 영향을 주게 된다. 이에 본 논문에서는 감쇠보정 영상의 count와 비감쇠보정 영상의 count의 비를 통하여 보정계수($e^{-{\mu}x}$)을 구하였고 이를 통해 측정 SUV에 대입하여 실제 SUV를 추정하는 방법에 대하여 고찰해보았다. 실험장비로는 본원에서 사용하고 있는 Biograph mCT S(40)_SIMENS을 촬영 장비로 이용하였고, phantom은 micro phantom을 사용하였다. 팬텀 실험방법은 micro phantom에 metal artifact를 발생시켜 촬영한 뒤 감쇠보정 영상과 비 감쇠보정 영상으로 재구성하였다. 그리고 SIMENS 사의 Sygo.via VA11A 프로그램을 이용 감쇠보정 영상과 비 감쇠보정 영상의 count를 측정하고 이를 통해 보정계수를 구하여 Metal artifact 발생 부위와 Metal artifact 발생 직전 부위의 보정계수를 비교 분석해 보았다. 임상영상에서는 본원에 내원한 환자 10명($66{\pm}15$세)의 데이터를 이용하여 여러 장기의 평균 보정계수를 계산하였고, Metal artifact가 발생한 연부조직의 보정계수와 metal artifact가 발생하기 직전의 연부조직의 보정계수를 비교 분석하였다. 분석결과 phantom 실험에서는 밝은 artifact 부분에서의 보정 계수는 Metal artifact가 발생하지 않은 부분에서의 보정계수보다 평균 12%증가 되게 나타났다. 어두운 artifact 부분에서의 보정계수는 발생하지 않은 부분에서의 보정계수보다 6% 감소 되게 나타났다. 또한 phantom 실험결과 본 논문에서 사용한 식을 이용한 추정 SUV가 실제 SUV와 유의미한 차이가 없다는 것을 확인 할 수 있었다. 임상영상에서는 normal 장기의 보정계수를 계산 하였고, 이를 이용한 각 장기의 평균 보정계수를 계산하여 그래프를 작성하였다. 그리고 이 결과 값을 통해 CT number가 큰 조직 일수록 보정계수도 커지는 상호 비례 관계를 확인 할 수 있었다. 또한 metal artifact시 밝은 artifact 부분의 연부조직 보정계수는 metal artifact가 발생 하지 않은 연부조직 보정계수에 비해 평균 20% 증가, 그리고 어두운 artifact 부분은 10% 감소된 것으로 나타났다. 그래프로 작성한 soft tissue 평균값과 비교 하였을 때는 metal artifact가 발생 하지 않은 연부조직에 비해 밝은 artifact 부위는 평균 19% 증가 어두운 artifact 부위는 평균 9% 감소 된 것으로 나타났다. 즉 경우에 따라 각 개인의 보정계수를 계산 할 필요 없이 그래프로 작성한 평균값을 간편하게 활용 할 수 있을 것으로 사료된다. 이와 같이 실험결과로 보아 본 논문에서 제시하였던 감쇠보정 영상과 비 감쇠보정 영상에서의 count의 비를 통해 metal artifact가 발생하지 않는 부위의 보정계수와 발생한 부위의 보정계수를 구하고, 이를 활용하여 측정 SUV에 대입하여 실제 SUV를 추정하는 방법 역시 metal artifact 발생 부위의 더 정확한 정량분석 위하여 고려 해볼 수 있는 대안이 될 수 있을 것이라 사료 된다. Purpose Because of many advantages, PET-CT Scanners generally use CT Data for attenuation correction. By using CT based attenuation correction, we can get anatomical information, reduce scan time and make more accurate correction of attenuation. However in case metal artifact occurred during CT scan, CT-based attenuation correction can induce artifacts and quantitative errors that can affect the PET images. Therefore this study infers true SUV of metal artifact region from attenuation corrected image count -to- non attenuation corrected image count ratio. Materials and Methods Micro phantom inserted $^{18}F-FDG$ 4mCi was used for phantom test and Biograph mCT S(40) is used for medical test equipment. We generated metal artifact in micro phantom by using metal. Then we acquired both metal artifact region of correction factor and non metal artifact region of correction factor by using attenuation correction image count -to- non attenuation correction image count ratio. In case of clinical image, we reconstructed both attenuation corrected images and non attenuation corrected images of 10 normal patient($66{\pm}15age$) who examined PET-CT scan in SNUH. After that, we standardize several organs of correction factor by using attenuation corrected image count -to- non attenuation corrected count ratio. Then we figured out metal artifact region of correction factor by using metal artifact region of attenuation corrected image count -to- non attenuation corrected count ratio And we compared standard organs correction factor with metal artifact region correction factor. Results according to phantom test results, metal artifact induce overestimation of correction factor so metal artifact region of correction factors are 12% bigger than the non metal artifact region of correction factors. in case of clinical test, correction factor of organs with high CT number(>1000) is $8{\pm}0.5%$, correction factor of organs with CT number similar to soft tissue is $6{\pm}2%$ and correction factor of organs with low CT number(-100>) is $3{\pm}1%$. Also metal artifact correction factors are 20% bigger than soft tissue correction factors which didn't happened metal artifact. Conclusion metal artifact lead to overestimation of attenuation coefficient. because of that, SUV of metal artifact region is overestimated. Thus for more accurate quantitative evaluation, using attenuation correction image count -to-non attenuation correction image count ratio is one of the methods to reduce metal artifact affect.

저선량 흉부전산화단충촬영의 흡기 영상과 폐기능이 정상인 성인에서 호기 말 폐 감쇄도 증가 정도와 연령 및 흡연과의 연관성

권성연 ( Sung Youn Kwon ),황용일 ( Yong Il Hwang ),윤호일 ( Ho Il Yoon ),이재호 ( Jae Ho Lee ),이춘택 ( Choon Taek Lee ),이경원 ( Kyung Won Lee ) 대한결핵 및 호흡기학회 2008 Tuberculosis and Respiratory Diseases Vol.65 No.6

연구배경: 호기말에 흉부 촬영을 시행하면 폐 내의 공기의 부피가 감소되어 폐 감쇄도가 증가한다. 이런 폐 감쇄도의 변화가 국소적으로 저하되는 공기 가둠 현상에 대해서는 일부 연구들이 있었으나 전체 폐의 전반적인 감쇄도 변화에 대한 연구는 거의 없고, 특히 정상인을 대상으로 한 연구는 거의 없다. 저자들은 호흡기 질환이 없으며 폐기능 및 흡기 전산화단층촬영이 정상 소견이고 호기 영상에서 국소적인 공기 가둠 현상이 없는 100명을 대상으로 연구를 수행하였다. 방법: 흉부 전산화단층촬영 영상에서 24개의 지점을 정하고, 흡기 및 호기 시 각 지점에서 폐 음영도를 측정한 후 호기말 폐 감쇄도 증가와 흡연량, 연령 사이의 상관관계를 알아보았다. 결과: 연구 대상 100명의 연령은 중앙값 49.0세(범위 25∼71세)였고, 평균 흡연량은 22.5±17.0갑년이었다. 연령과 폐 감쇄도의 증가 사이에는 유의한 음의 상관관계가 있었으며 이는 흡연의 효과를 보정하였을 때에도 유지되었고, 연령을 기준으로 세 군으로 나누어 폐 감쇄도의 증가 정도를 비교하였을 때에도 유의한 차이가 있었다. 흡연량과 호기말 폐 감쇄도의 증가 사이에는 유의한 음의 상관관계가 관찰되었으나 연령을 보정하였을 때에는 유의성이 감소하였다. 결론: 흡기-호기 시의 폐의 전반적인 감쇄도 변화 정도는 연령과 상관관계가 있으며, 노화를 반영할 가능성이 있다. Background: The attenuation of the lung parenchyma increases on expiration as a consequence of decreased air in the lung. Expiratory CT scans have been used to show air trapping in patients with chronic airway disease and diffuse parenchymal disease and also in asymptomatic smokers. Although there have been several reports investigating the regional air trapping on a expiratory CT scan, there have been only a few reports evaluating the changes of whole lung attenuation with considering its clinical significance, and especially in healthy subjects. The purpose of this study was to evaluate the correlation of an expiratory increase of lung attenuation with age and smoking in healthy subjects. Methods: Asymptomatic subjects who underwent a low dose chest CT scan as part of a routine check-up and who showed normal spirometry and a normal inspiratory CT scan were recruited for this study. We excluded the subjects with significant regional air trapping seen on their expiratory CT scan. Lung attenuation was measured at 24 points of both the inspiratory and expiratory CT scans, respectively, for 100 subjects. The correlations between an expiratory increase of the lung attenuation and the amount of smoking, the patient`s age and the results of spirometric test were assessed. Results: There were 87 men and 13 women included in this study. Their median age was 49.0 years old (range: 25∼71). Sixty current smokers, 24 ex-smokers and 16 non-smokers were included. As age increased, the expiratory increase of lung attenuation was reduced at every measuring points (r=-0.297∼-0.487, Pearson correlation). The statistical significance was maintained after controlling for the effect of smoking. Smoking was associated with a reduction of the expiratory increase of lung attenuation. But the significance was reduced after controlling for the patient`s age. The FEV1, FVC, FEV1/FVC and FEF25∼75% were not associated with an expiratory increase of lung attenuation. Conclusion: The expiratory increase of lung attenuation in subjects with a normal inspiratory CT scan was negatively correlated with age. It was also reduced in heavy smokers. It may reflect aging and the smoking related changes. (Tuberc Respir Dis 2008;65:457-463)

Iterative Simultaneous Attenuation Correction and Activity Estimation for Time-of-Flight Positron Emission Tomography

이남용,Kim You Suk,Lim Hyun Keong,최용 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.8

An accurate quantitative estimation of the radioactive tracer distribution in positron emission tomography (PET) requires correction of the observed emission data for the attenuation factors. For this purpose, transmission data, provided by X-ray computerized tomography (CT) or magnetic resonance imaging (MRI), are often used to measure the attenuation rate in observed PET data. In this paper, we propose an iterative simultaneous attenuation correction and activity estimation method without transmission data. In each iteration, the proposed method disperses the attenuation effect in the time-of-flight (TOF) PET sinogram in each line-of-response to the current iterates for the activity estimate, then uses that iterate to update the attenuation rate in the TOF PET sinogram, and finally use that updated attenuation rate in computing the next iterates. The simulation result shows that the proposed method corrects attenuation artifact accurately and produces activity estimates comparable to reconstructed ones from attenuation-free data.

Optical properties in waters around the Mendeleev Ridge related to the physical features of water masses

Zhao, J.,Wang, W.,Kang, S.H.,Yang, E.J.,Kim, T.W. Pergamon Press 2015 Deep-sea research. Part II, Topical studies in oce Vol.120 No.-

Irradiance profiles were measured during the Korean 2012 summer Arctic Ocean cruise and optical properties were studied. The optical attenuation coefficient in all surface waters was low, as the nutrients in the surface layers became exhausted and phytoplankton growth was only possible at the subsurface where optimal conditions of nutrients and sufficient illumination existed. This high attenuation zone was at about 40-60m. The attenuation properties were categorized to three types. Type-1 waters had weaker maximum attenuation coefficients and were located at the Chukchi Plateau and the north margin of the study region. Type-2 water had an intense maximum of attenuation coefficient up to 0.56/m located on west flank of Mendeleev Ridge and continental slope of East Siberian Sea. Two integral parameters, attenuation depth and optical thickness, were mapped by spatial distribution. The attenuation depth was basically shallower (40m) to the west and deeper to the east (100m). The averaged optical thickness at the level of 30-60m was the main zone of high attenuation. Both the optical attenuation property and the physical features of the water indicated two subsurface water masses: one is the cold shelf water well mixed with river water and transported to the east by a subsurface current along the East Siberian Slope. The other is the warmer water from the Pacific with lower nutrients and transported to the northwest along the north margin of the observed region. A cyclonically re-circulated branch of shelf water passing over the Chukchi Abyssal Plain was described in this study.

Evaluation of the Interaural Attenuation for Pure Tone Audiometry in Korean

Kye Hoon Park,Young Joo Park,Go-Eun Jun,Sol Kil Oh,Chi-Kyou Lee 대한청각학회 2011 Journal of Audiology & Otology Vol.15 No.1

Background and Objectives: The masking should be used in pure tone audiometry when the difference between the air-conduction threshold of the tested ear and the bone-conduction threshold of the non-tested ear is more than interaural attenuation (IA). But the standardized average value of IA in Korean has not been evaluated until now. The purpose of this study is to evaluate the interaural attenuation in Korean population. Subjects and Methods: Of the patients who visited our department from March, 2007 to August, 2009, 44 patients were selected who had unilateral severe sensorineural hearing loss or deafness and contralateral normal hearing. When the difference between air-conduction threshold with and without masking was more than 10 dB, the interaural attenuation at each frequency was obtained by subtracting the contralateral bone conduction from the air-conduction threshold without masking. Results: The interaural attenuations at each frequency were 45-75 dB (250 Hz), 50-75 dB (500 Hz), 40-75 dB (1 kHz), 45-85 dB (2 kHz), 50-90 dB (4 kHz). 77.2% of the subjects showed interaural attenuation of 55-65 dB at 250 Hz, and 80.9% in 50-60 dB at 500 Hz, 79.5% in 55-65 dB at 1 kHz, 83.4% in 45-60 dB at 2 kHz, and 76.4% in 50-65 dB at 4 kHz. Most of the patients were distributed 15-25 dB higher than the minimal interaural attenuation at 1 kHz. At 2 kHz and 4 kHz, most of the patients were distributed around 15 dB of the minimal interaural attenuation. Conclusions: These results can be used as reference values for masking of pure tone audiometry. But, further studies with large population should be done to get more precise results and contributing factors to IA values.

재난환경내 건축재료 및 연기에 따른 드론 전파 감쇠에 대한 연구

김태동,염인수 한국산학기술학회 2022 한국산학기술학회논문지 Vol.23 No.12

재난환경에서 연기와 건축물재료에 따른 전파 감쇠에 관한 실험적 연구를 제시하였다. 화재와 같은 재난환경이 발생하면 드론 운용시 건축자재에 의한 통신장애나 화재 시 발생하는 연기로 인해 전파 감쇠가 발생한다. 이에 따라 본 논문에서는 벽체와 연기에 따른 드론의 전파 특성을 비교·분석하였다. 먼저 벽체 종류 및 두께에 따른 전파 감쇠를 분석하기 위해 완전 차폐 공간인 무향실(3m x 1m x 1m)에서 4가지 벽체에 해당하는 전파 특성을 실험하였다. 또한 연기밀도에 따른 전파 특성 시험을 위해 컨테이너 공간(5.8m x 2.8m x 2.2m)을 구성하였고 광 소멸법을 이용하여 공간내 동일한 연기밀도를 구성한 후 4종류의 연기에 대한 전파감쇠를 비교하였다. 본 연구에서는 실험에 사용될 픽스호크 기반의 모듈을 제작하고 비행관제용 433㎒, 제어용 2.4㎓, 그리고 영상수신용 5㎓ 대역에서 전파 감쇠에 관한 연구를 수행하였다. 벽체 종류 및 두께에 따라 수신감도가 크게 감소하여 감쇠의 주요 원인이 되었다. 연기에 의한 전파 감쇠는 크지 않지만, 우레탄, 플라스틱, 고무 등의 연료는 목재에 비해 상대적으로 감소하였으며, 2.4㎓와 영상수신용 5㎓대역에서는 감소폭이 상대적으로 크게 나타났다. This study examined microwave attenuation according to the smoke and wall type in a disaster environment. When a disaster such as a fire occurs, there is a distortion of drone communication within the building. An experimental study was performed to compare the microwave attenuation of drones according to the building materials and smoke. First, the microwave characteristics corresponding to the four types of walls in a specially designed anechoic chamber (3m x 1m x 1m) were examined to determine the microwave attenuation for building materials. The propagation attenuation was studied according to the four types of smoke with the same density in the container space (5.8m × 2.8m × 2.2m). In this study, a communication module based on Pixhawk was designed and was conducted on microwave attenuation in 433㎒ for mission mode, 2.4㎓ for remote controller control, and 5㎓ for image receiving. The microwaves were not transmitted and decreased significantly depending on building materials at the radio frequency, which is the leading cause of attenuation. Although microwave attenuation was not huge according to the fuels in smoke, fuel like urethane, plastic, and rubber have a relatively reduced compared to wood. In the 2.4㎓ and 5㎓ bands, the decrease in microwave energy was relatively large.

확률적 정량모델을 이용한 토양에서의 바이러스 저감 평가

박정안(Jeong Ann Park),김재현(Jae Hyun Kim),이인(In Lee),김성배(Song Bae Kim) 大韓環境工學會 2011 대한환경공학회지 Vol.33 No.7

본 연구의 목적은 미국 환경보호청에서 개발한 확률적 정량모델인 VIRULO 모델의 구성과 특성을 분석하는 것이다. 이 모델은 몬테카를로 방법을 이용하여 수리지질학적 차단벽으로써 토양의 바이러스 저감능을 평가할 수 있는 모델이다. 모델에 사용된 지배방정식은 크게 불포화 지역에서의 물의 흐름식과 바이러스의 이동식으로 구성되어 있다. 사용되는 파라미터들 중, 물의 흐름과 관련된 파라미터는 11종류의 토양에 대하여 UNSODA 데이터베이스로부터 얻어진 것 들이며, 바이러스와 관련된 파라미터 값들은 다섯 종류의 바이러스에 대하여 문헌조사를 통해 정리된 것이다. 모델은 목표로 하는 바이러스 저감 역치값과 특정 조건에서 몬테카를로 모사를 통해 얻어진 토양의 바이러스 저감인자를 비교하여, 목표로 하는 바이러스 저감 역치값에 도달하지 못하는 확률을 결정한다. 그리고, 몬테카를로 모사횟수와 목표 역치값에 도달하지 못한 횟수를 결과물로 제시한다. 11개의 USDA 토양을 대상으로 바이러스 저감을 평가한 결과, 양질사토와 모래의 바이러스 저감능이 점토나 미사 계열의 토양에 비하여 상당히 떨어지는 것으로 평가되었다. 5종의 바이러스를 대상으로 저감을 비교한 결과, 바이러스 간에 저감 정도에 차이가 있는 것으로 나타났으며, 그 중 폴리오바이러스의 저감 정도가 가장 큰 것으로 분석되었다. 그리고, 토양 함수량이 증가함에 따라 토양의 바이러스 저감능이 급격하게 감소하였으며, 토양의 깊이가 증가함에 따라 바이러스 저감능이 비선형적으로 증가하였다. 본 연구에 의하면, VIRULO 모델은 지중환경에서의 바이러스 위해성 평가에 사용될 수 있는 유용한 스크리닝 도구로 판단된다. The objective of this study was to analyze VIRULO model, a probabilistic quantitative model, which had been developed by US Environmental Protection Agency. The model could assess the viral attenuation capacity of soil as hydrogeologic barrier using Monte Carlo simulation. The governing equations used in the model were composed of unsaturated flow equations and viral transport equations. Among the model parameters, those related to water flow for 11 soil types were from UNDODA data, and those related to 5 virus species were from the literatures. The model compared the attenuation factor with threshold of attenuation to determine the probability of failure and presented the exceedances and Monte Carlo runs as output. The analysis indicated that among 11 USDA soil types, the viral attenuation capacity of loamy sand and sand were far lower than those of clay and silt soils. Also, there were differences in the attenuation in soil among 5 viruses with poliovirus showing the highest attenuation. The viral attenuation capacity of soil decreased sharply with increasing soil water content and increased nonlinearly with increasing soil barrier length. This study indicates that VIRULO model could be considered as a useful screening tool for viral risk assessment in subsurface environment.

섬유/플라스틱 사출성형 복합재료의 음향방출 진폭 분포에 대한 감쇠효과

최낙삼,Takahashi, Kiyoshi 韓國非破壞檢査學會 1998 한국비파괴검사학회지 Vol.18 No.1

짧은 섬유로 강화된 열가소성수지의 복합재료를 대상 재로로 하여 AE의 발생위치(AE source location)를 구하고 AE신호의 진폭분포에 미치는 감쇠 손실(attenuation loss)의 영향을 정량적으로 검토했다. 모의 AE파를 이용하여 측정된 감쇠율은 시험편내의 섬유체적함유율의 증가에 따라 단순 선형관계식으로 예상되는 값보다 더 작았다. 시험편에서 계측된 AE진폭분포에 감쇠손실을 보정한 결과, 시험편의 게이지부에 설정된 각 구역에서 서로 유사한 수준의 진폭분포가 나타났다. 또한 보정된 AE진폭은 시험편의 변형이 진행됨에 따라 더욱 크게 되었다. 따라서, AE진폭을 이용한 고분자복합재료의 손상해석에서는 AE파의 감쇠효과를 보정해야 됨이 확인되었다. The attenuation of acoustic emission (AE) waves was evaluated for injection- molded short-fiber-reinforced thermoplastic composites employing simulated AE waves. Values of attenuation coefficient (α) decreased more with increasing fiber volume fraction (V) than that expected from a simple linear relation between αand V. The effect of wave attenuation was taken into account in a quantitative analysis of the AE peak amplitude distribution which was obtained from each zone partitioned in a specimen gage portion. The amplitude distribution compensated for the measured attenuation loss was exhibited almost similar in every zone of the specimen. Consequently, it was shown that the AE amplitudes obtained from fiber/plastic composites were considerably affected by the attenuation.