• 대한방사선기술학회지:방사선기술과학
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• 제39권1호
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• pp.51-57
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• 2016

뇌 자기공명영상(Magnetic Resornance Imaging; MRI)에서 검사 중 발생되는 소음을 줄이기 위한 기법으로 경사 파형을 변경한 Quiet $T_2$-weighted Turbo Spin-Echo(이하 Q-$T_2$)와 일반적으로 사용되는 $T_2$-weighted Turbo Spin-Echo(이하 $T_2$) 영상의 소음수준 및 영상의 질을 비교하여 그 유용성을 알아보고자 하였다. 3.0T MR 기기로 뇌 MR 검사를 받은 60명(남자 29명, 여자 31명, 평균 연령 60.1세)의 환자를 대상으로 하였다. Q-$T_2$와 $T_2$ 각각의 영상에서 소음 및 심박동수를 측정하였다. 정량적 분석은 Q-$T_2$와 $T_2$의 SNR, CNR, SIR 값을 측정한 뒤 독립표본 T검정을 이용하여 통계적 분석을 하였다. 정성적 분석은 Q-$T_2$와 $T_2$의 전체적인 영상의 질에 대하여 육안으로 평가하였다. 평가는 5점 척도로서 우수(excellent) 5점, 양호(good) 4점, 보통(fair) 3점, 불량(poor) 2점, 평가불가(unacceptable) 1점으로 평가하였다. Q-$T_2$와 $T_2$ 검사 중 평균소음과 peak소음은 Q-$T_2$가 기존 $T_2$에 비해 각각 $15dB_A$, $10dB_A$ 감소하였다. 또한 각각의 검사 중 120초 동안 심박동수의 평균값은 Q-$T_2$에서 더 낮은 값으로 나타났지만 통계적인 유의성은 없었다. 정량적 분석의 결과 CNR과 SIR은 유의한 차이가 없었으며, SNR은 Q-$T_2$가 더 낮은 평균값을 보임으로서 유의한 차이를 보였다(p<0.05). 정성적 분석은 59개의 Q-$T_2$와 $T_2$ 영상의 질이 동일하게 우수(excellent) 5점으로 평가되었으며, 1개의 영상에서 모션 아티팩트로 인해 양호(good) 4점으로 평가되었다. Q-$T_2$는 기존의 $T_2$와 같이 검사시간 및 진단의 정확도는 동일하지만 소음을 효과적으로 감소시킬 수 있으며, 이로인하여 환자 편의를 향상시킬 수 있을 것으로 사료된다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2010년도 춘계학술대회 논문집
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• pp.48-48
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• 2010

Sound quality and NVH-issues(Noise, Vibration and Harshness) of vehicles has become very important for car manufacturers. It is interpreted as among the most relevant factors regarding perceived product quality, and is important in gaining market advantage. The general sound quality of vehicles was gradually improved over the years. However, today the development cycles in the automotive industry are constantly reduced to meet the customers' demands and to react quickly to market needs. In addition, new drive and fuel concepts, tightened ecological specifications, increase of vehicle classes and increasing diversification(increasing market for niche vehicles), etc. challenge the acoustic engineers trying to develop a pleasant, adequate, harmonious passenger cabin sound. Another aspect concerns the general pressure for reducing emission and fuel consumption, which lead to vehicle weight reductions through material changes also resulting in new noise and vibration conflicts. Furthermore, in the context of alternative powertrains and engine concepts, the new objective is to detect and implement the vehicle sound, tailored to suit the auditory expectations and needs of the target group. New questions must be answered: What are appropriate sounds for hybrid or electric vehicles? How are new vehicle sounds perceived and judged? How can customer-oriented, client-specific target sounds be determined? Which sounds are needed to fulfil the driving task, and so on? Thus, advanced methods and tools are necessary which cope with the increasing complexity of NVH-problems and conflicts and at the same time which cope with the growing expectations regarding the acoustical comfort. Moreover, it is exceedingly important to have already detailed and reliable information about NVH-issues in early design phases to guarantee high quality standards. This requires the use of sophisticated simulation techniques, which allow for the virtual construction and testing of subsystems and/or the whole car in early development stages. The virtual, testing is very important especially with respect to alternative drive concepts(hybrid cars, electric cars, hydrogen fuel cell cars), where complete new NVH-problems and challenges occur which have to be adequately managed right from the beginning. In this context, it is important to mention that the challenge is that all noise contributions from different sources lead to a harmonious, well-balanced overall sound. The optimization of single sources alone does not automatically result in an ideal overall vehicle sound. The paper highlights modern and innovative NVH measurement technologies as well as presents solutions of recent NVH tasks and challenges. Furthermore, future prospects and developments in the field of automotive acoustics are considered and discussed.