복부검사에 있어 관전압 제어 software의 유용성에 관한 연구

이종옥(Jong Ok Lee),이혜진(Hye Jin Lee),김홍식(Hong Sik Kim),임기빈(Ki Bin Im),강성호(Sung Ho Kang),임재식 대한CT영상기술학회 2012 대한CT영상기술학회지 Vol.14 No.1

I. Purpose The purpose of this study is to compare and analyze quantitatively and qualitatively dose and image quality between the group using no tube voltage control software and the group using tube voltage control software and noise reduction software and so examine the usefulness of examination methods using tube voltage control software and noise reduction software. II. Materials and methods Among the patients who had visited this Hospital and had received abdominal CT examinations from June to July 2011, this study selected 100 patients using no tube voltage control software and 100 patients using tube voltage control software. 1. Dose By using the total CTDIDLP values indicated on the monitor after examinations, this study compared and analyzed the doses between the group using no tube voltage control software and the group using tube voltage control software. 2. Quality of image This study divided the group using no tube voltage control software and the group using tube voltage control software and noise reduction software simultaneously and so compared their contrast noise ratio(CNR). This study selected 50 patients by each group at random and so measured aorta, portal vein, liver, and psoas muscle for CNR. CNR was calculated by the following formula(Formula-1). (Target HU - Target Noise)/Target Noise, (Aorta HU - Aorta Noise)/ Aorta Noise (식-1) 3. Noise reduction software validation This study evaluated the usefulness of noise reduction software by using diluted contrast agents. In order to obtain the range similar to 50~300, that is, the mean value of aorta, portal vein, liver, and psoas muscle, which was used in clinical studies, this study diluted physiological saline 40 ml and contrast agent 1.5, 1.2, 1.0, 0.8, 0.5, and 0.2 ml in 6 syringes, and then acquired the control groups which were regarded as references. In order to evaluate tube voltage control software and noise reduction software, this study decreased gradually exposure conditions and so acquired the experimental groups which increased HU and noise value. The control groups as reference images acquired their images in the condition of 120 kVp and 200 mAs. The experimental groups for comparison acquired their images in the condition of 100 kVp and 100 mAs. The experimental groups used noise reduction program and so recomposed images by 5 stages and then were compared with the control groups for noise values. III. Result The mean age, scan range and CTDIDLP value of the group using no tube voltage control software were Age 59.6, 495.1, and 468mGycm. In contrast, the mean age, scan range and CTDIDLP value of the group using tube voltage control software were Age 58.4, 494.7, and .265.6mGycm. In order to test the significance between groups, this study conducted independent T-test. According to such results, gender (p=0.462) and range(p=0.948) showed no significant difference. However, mean CTDIDLP values decreased by 43% in the group using tube voltage control software and also showed the statistically significant difference(p=0.000). According to the results of comparing with CNR which was set up as the reference in order to measure the quality of images, the group using tube voltage control software increased HU and noise values in comparison with the group using no tube voltage control software. The group using both tube voltage control software and noise reduction software simultaneously could decrease noise values without changing HU values greatly in comparison with the group using only tube voltage control software and also showed statistically significant results. Also, according to the results of comparing noise values, in using the noise reduction software of Stage 2-3, the noise value similar to that of the control group could be obtained. IV. Conclusion This study tried to examine whether using tube voltage control software could decrease dose and using noise reduction software could decrease the occurrence of no 복부 CT검사에 있어 관전압 제어 software를 사용하지 않은 그룹과 관전압과 noise reduction software를 적용한 그룹의 선량과 영상의 질을 정량, 정성적으로 비교 분석하여 관전압과 noise reduction software를 적용한 검사 방법의 유용성에 대해 알아보고자 한다. 대상 및 방법 2011년도 6~7월까지 본원에 내원하여 복부 CT검사를 시행한 환자 중 관전압 제어 software를 사용하지 않고 검사를 시행한 환자 100명과 관전압 제어 software를 적용하여 검사를 시행한 환자 100명을 무작위로 선정하였다. 1. 선량 검사 후 모니터에 표시되는 Total CTDIDLP 값을 사용하여 관전압 제어 software를 사용하지 않은 그룹과 관전압 제어 software를 사용한 그룹의 선량을 비교 분석하였다. 2. 영상의 질 관전압 제어 software를 사용하지 않은 그룹과 관전압 제어와 noise reduction software를 동시에 사용한 두 그룹으로 나누어 contrast noise ratio(이하 CNR)를 비교하였다. 각 그룹당 50명을 무작위로 선정하였으며 CNR은 Aorta, Portal vein, Liver, Psoas muscle을 측정하였다. CNR은 아래의 식으로 구하였다 (식-1). (Target HU - Target Noise)/Target Noise, (Aorta HU - Aorta Noise)/ Aorta Noise (식-1) 3. Noise reduction software validation 조영제 희석 Sample을 이용하여 Noise reduction software의 유용성을 평가하였다. 임상연구에서 사용된 Aorta, portal vein, liver psoas muscle의 평균 HU값인 50~300과 유사한 범위를 얻기 위해 6개의 syringe에 생리식염수 40ml와 조영제 1.5, 1.2, 1, 0.8, 0.5, 0.2 ml를 희석한 후 기준이 되는 대조군을 구하였다. 관전압 제어 software와 noise reduction software의 평가를 위해 노출조건을 점차적으로 감소시켜 HU와 noise값이 증가된 실험군을 구하였다. 기준 영상인 대조군은 120 kVp, 200 mAs, 비교를 위한 실험군은 100 kVp, 100 mAs 조건에서 영상을 획득하였고, 실험군은 noise reduction 프로그램을 이용하여 5단계로 영상을 재구성한 후 대조군의 noise 값과 비교 분석하였다. 결과 관전압 제어 software을 사용하지 않은 그룹의 평균나이, 스캔범위, CTDIDLP 값은 59.6세, 495.1, 468.5mGyㆍcm이었고, 관전압 제어 software을 사용한 그룹은 58.4세, 494.7, 265.6mGyㆍcm이었다 그룹 간 유의성 검증을 위해 실시한 independent T-test 결과, 성별(p=0.462)과 range(p=0.948)에서는 유의한 차이를 보이지 않았다. 그러나 평균 CTDIDLP 값은 관전압 제어 software를 사용한 그룹에서 43% 감소하였으며 통계적으로도 유의한 차이(p=0.00)를 보였다. 영상의 질을 측정하기 위해 기준으로 설정한 CNR을 기준으로 결과를 정리하면 관전압 제어 software를 사용하지 않은 그룹과 비교하여 관전압 제어 software를 사용한 그룹에서 HU값과 Noise값이 증가되었고, 관전압 제어 software를 사용환 그룹과 비교하여 관전압 제어 software와 noise reduction software를 함께 사용한 그룹에서 HU값의 큰 변화없이 Noise를 감소시킬 수 있었으며, 통계적으로도 유의한 결과를 나타냈다 또한, 실험군의 Noise 값을 비교한 결과 2-3단계 Noise reduction. software 적용 시 대조군과 유사한 Noise 값을 얻을 수 있었다. 결론 관전압 제어 software를 이용한 선량감소 효과와 저 관전압 사용으로 인한 noise의 발생을 software 처리과정을 통해 감소시켜 영상의 진단적 가치를 유지할 수 있는가를 알아보고자 하였다. 관전압 제어 software의 사용으로 인해 선량을 40% 정도 감소시킬 수 있었으며, noise 제거 software의 적용은 저 관전압 사용으로 인한 영상의 noise 증가를 관전압 제어 software를 사용하지 않고 촬영한 영상의 noise와 비슷한 수준으로 감소시킬 수 있었다. 따라서 복부 CT 검사에 있어 관전압 제어 software와 noise 제거 software의 적용은 진단적 영상의 질을 담보함과 동시에 선량을 감소시킬 수 있는 방법일 것이다.

Noise-reduction Function and its Affecting Factors of Plant Communities

( Xiu-hua Song ),( Qian-qian Wu ),( Dong-ming Yu ),( Piao Yong-ji ),( Tae-dong Cho ) 한국환경과학회 2016 한국환경과학회지 Vol.25 No.10

In this study, we investigated the relationship between noise reduction and the community structure of nine groups of typical plant communities as well as the reduction in noise at different frequencies. The semantic differential method was adopted to explore the perception of noise reduction. The results indicated that there was a significantly positive correlation between noise reduction and coverage , a significantly negative correlation between noise reduction and bifurcate height, and a negative correlation between noise reduction and bare rate. However, there was no significant correlation between noise reduction and height, diameter at breast height, or crown width. The reduction of middle-frequency noise was better than that of low- and high-frequency noise. The indicators "quiet" and "calm" showed that plant communities could reduce the noise perceived by humans. However, overly dense woodland caused nervousness, fear, depression, and other negative effects. Relatively open environments and those with large forest gaps obtained the highest evaluation.

도심지 내 복층 저소음포장 설치에 따른 소음저감 사례연구

정종석,손정락,이수형,양홍석 한국도로학회 2016 한국도로학회논문집 Vol.18 No.6

PURPOSES : In this study, noise reduction effect of a two-layer porous asphalt pavement was investigated through site measurement and computer simulation. METHODS : To examine noise reduction effect, a 3 km long quiet pavement was installed by removing previous normal pavement, which had a rather low porosity. The studied site was a high-rise apartment building surrounded by the quiet pavement and Seoul ring road with heavy traffic volume, indicating relatively high background noise. RESULTS : The measurement result before and after installing the quiet pavement showed a noise reduction effect of 4.3 dB(A) at a distance of 7.5 m from the road. After validating the accuracy of simulation using SoundPLAN, the reduction in SPL(sound pressure level) at the facades by the quiet pavement was predicted by considering five different road conditions generating traffic noise from each road or in the combination of the quiet pavement and Seoul ring road. In the case of no noise from Seoul ring road, noise reduction at the facades was 4.2 dB(A) on average for 702 housing units. With background noise from Seoul ring road, however, the average SPL decreased to 2.0 dB(A). Regarding subjective response of noise, the number of housing units with a noise reduction of over 3 dB(A) was 229 out of 706 units (approximately 32%). For 77 housing units, the noise reduction was between 1~3 dB(A), while it was less than 1 dB(A) for 400 housing units. CONCLUSIONS : The overall result indicates that the quiet pavement is useful to reduce noise evenly at low and high floors compared to noise barriers, especially in the urban situation where background noise is low.

텔레메틱스 기반의 통화음질향상을 위한 잡음제거 알고리즘의 성능비교

김형국,최홍재 한국ITS학회 2012 한국ITS학회논문지 Vol.11 No.1

다양한 잡음환경에 노출되는 텔레메틱스 기반의 음성 통화 시스템에서 고품질의 통화 품질을 제공하기 위해서는 저연산량을 가지며 효과적으로 배경 잡음을 제거할 수 있는 잡음제거 알고리즘이 요구된다. 본 논문에서는 Mel-Filter 기반의 잡음제거 알고리즘을 제안하며, 제안된 알고리즘을 기존 잡음제거 알고리즘들과 비교하여 설명한다. 자동차 잡음과 배블 잡음 환경에서 잡음제거 알고리즘의 성능 측정 결과, 제안된 Mel-Filter 기반의 잡음제거 알고리즘이 기존 잡음제거 알고리즘들에 비해 비슷한 PESQ 성능에 적은 연산량을 가지는 장점을 가지고 있으며, 제안된 잡음제거 알고리즘이 텔레메틱스 단말기에서 효과적으로 잡음을 제거할 수 있음을 입증하였다. To provide high voice quality of real-time voice communication based on telematics exposed to various noise environments, the noise reduction algorithm with low computing load is required to effectively remove the noise. In this paper, we propose a noise reduction algorithm based on Mel-Filter and illustrate the proposed algorithm comparing with conventional noise reduction algorithms. As a experimental result that evaluates the performance of the noise reduction algorithms under the car and babble noise environments, the proposed noise reduction algorithm has the lower computing load with the similar PESQ score compared to the conventional noise reduction algorithms. It proves that the proposed noise reduction algorithm can efficiently remove the noise in mobile telematics.

A Study on the Noise Reduction of Reciprocating Type Air Compressors

Lee Kwang-Kil,Kim Kwang-Jong,Lee Gwan-Hyung,Park Jae-Suk,Son Doo-ik,Kim Bong-Ki,Lee Dong-Ju The Korean Society of Safety 2004 International Journal of Safety Vol.3 No.1

This paper deals with the noise evaluation technique of a reciprocating air-compressor and its noise reduction. The reciprocating air-compressors are widely used in the small, medium sized industrial firms, and lots of their employees are affected and irritated by their noise in the workplace. Thus, noise control actions should be taken appropriately by considering the hearing loss due to the occupational noise exposure. Lead-wrapping techniques are employed to identify the contribution of principal noise sources which are generally known as motor, belts, suction/discharge valves, moving pistons, and flow-induced noise caused by edges or discontinuities along the flow path e.g. expansions, contractions, junctions and bends etc .. As a result, main noise sources of the air-compressor can be categorized by the suction/discharge noise, valve noise, and compressed-air tank noise. Based on the investigations, mufflers are designed to reduce both the suction/discharge noise and the compressed-air tank noise. Instead of the conventional valve plate, polyethylene resin is used as a new one for the reduction of valve impact noise. In addition, attempts are made to reduce the valve noise propagation to the cylinder head and the compressor tank by using the insulation casings. As a result of the countermeasure plans, it can be achieved that the noise reduction of the air-compress is up to 10dB.

도로인접 아파트 단지의 교통소음 예측 및 저감방안

조창근(Chang-Geun Cho) 한국생활환경학회 2014 한국생활환경학회지 Vol.21 No.5

Various kinds of noise reduction plans should be reviewed in the initial planning stage of apartment complex construction because absorptive noise barriers are generally restrictive in reducing traffic noise. To address this issue, the author of this paper presents technical data for planning in order to reduce traffic noise in an apartment complex situated near the traffic road. In this study, traffic noise levels were simultaneously measured on the road and in the lower, middle and higher floors of subject apartment buildings which are located within two traffic roads and are influenced by its traffic noise. Consequently, noise reduction of the suggested noise reducing plans is predicted to investigate the effect of them as well. The study shows that the daytime average traffic volume for the 6-lane road is > 4,000 vehicles/h; for the 4-lane main road, the daytime average traffic volume is > 5,000 vehicles/h. The maximum traffic noise levels in B, C, and D buildings located near the traffic road of the subject apartment complex were measured to be 73.8 dB (A) during daytime and 70.0 dB (A) during nighttime. These values highly exceed the acceptable guidelines. This study suggests that the average noise reduction of absorptive sound proof tunnel showed 3.0 - 10.1 dB (A) which is larger than that of absorptive noise barriers.

녹화된 아날로그 영상의 화질 개선을 위한 잡음 연관성을 고려한 학습기반 잡음개선 기법

김성득(Sung Deuk Kim),임경원(Kyoung Won Lim) 大韓電子工學會 2010 電子工學會論文誌-SP (Signal processing) Vol.47 No.6

녹화된 아날로그 영상에 내재하는 잡음을 효과적으로 제거하기 위해서는 잡음의 실제 특성과 정도를 정확히 파악하는 것이 매우 중요하다. 본 논문에서는 실제 방송되는 아날로그 영상을 녹화하여 잡음의 특성을 분석한 후, 녹화된 아날로그 영상을 위한 효과적인 학습기반 잡음개선 방법을 제안한다. 먼저 녹화된 아날로그 영상의 잡음을 분석하여 무시할 수 없는 잡음의 연관성이 존재하는 것을 보임으로써, 전통적인 부가 백색 가우시안 잡음 (AWGN) 모델에 기반을 둔 잡음의 추정과 잡음 제거 방법이 가지는 한계를 설명한다. 또한 잡음의 연관성을 고려한 자기회귀 모델을 이용해서 녹화된 아날로그 영상에 내재하는 잡음을 추정하고 합성할 수 있음을 보이며, 추정된 자기회귀 모델을 이용해 학습기반 잡음제거 기법에 적용함으로써 비디오 잡음을 제거한다. 실험결과는 제안된 방법이 무시할 수 없을 정도로 잡음 연관성을 가진 실제 녹화된 아날로그 영상의 잡음 제거에 효과적으로 활용될 수 있음을 보여준다. In order to remove the noise contained in recorded analog video, it is important to recognize the real characteristics and strength of the noise. This paper presents an efficient training-based noise reduction method for recorded analog video after analyzing the noise characteristics of analog video captured in a real broadcasting system. First we show that there is non-negligible noise correlation in recorded analog video and describe the limitations of the traditional noise estimation and reduction methods based on additive white Gaussian noise (AWGN) model. In addition, we show that auto-regressive (AR) model considering noise correlation can be successfully utilized to estimate and synthesize the noise contained in the recorded analog video, and the estimated AR parameters are utilized in the training-based noise reduction scheme to reduce the video noise. Experiment results show that the proposed method can be efficiently applied for noise reduction of recorded analog video with non-negligible noise correlation.

선박 거주성 향상을 위한 선실 소음 저감 시스템 개발에 관한 실험적 연구

서영철,김득봉,김철승 해양환경안전학회 2023 해양환경안전학회지 Vol.29 No.6

선내 소음은 선원의 거주성과 건강을 위한 중요한 요소 중의 하나로, 선내 소음을 줄이기 위한 노력이 활발하게 진행되고 있다. 소음 저감 방법에는 수동소음제어(PNC) 방법과 능동소음제어(ANC) 방법이 있다. 자동차, 항공기와 달리 선박에서는 ANC를 이용한 소음 저감 대책이 미미한 실정이다. 본 연구는 능동소음제어(ANC)와 같이 방음판과 고주파진동원을 이용하여 기관실에 발생한 소음을 줄이고자 하였다. 이를 위해 아크릴 상자를 이용하여 실험 모형을 만들었고, 4가지 조건별로 소음 저감 효과를 측정하였다. 실험 결과는 다음과 같다. 첫째, 방음판은 55dB~85dB까지 모든 범위에서 소음 저감 효과가 있었다. 고주파진동원은 낮은 소음에서 효과가 없었으나, 70.8dB(A)과 85dB(A)와 같은 높은 소음에서는 효과가 있었다. 둘째, 방음판과 고주파진동원을 동시에 사용하는 경우에는 최대 -2.2dB(A) 만큼의 소음 저감 효과가 있었다. 본 실험의 결과는 아크릴판으로 제작한 실험모형에서 얻은 결과로 철판으로 된 실제 선박과 다를 수 있다. 추후 연구에서 실제 선박에서 사용하는 철판(재질과 두께, 구조를 고려)을 이용하여 실험하고자 한다. 이 연구가 선박에 승선하는 선원들의 거주성 향상과 건강 증진에 도움이 되기를 기대한다. Ship noise is one of the important factors for the living and health of seafarers, and efforts to reduce ship noise are actively underway. There are two methods of noise reduction: passive noise Control (PNC) and active noise control (ANC). Unlike cars and airplanes, ANC is not widely used for noise reduction on ships. This study aimed to reduce the noise generated in the engine room by using soundproof panels and high-frequency vibration generators, as well as active noise control (ANC). For this purpose, an experimental model was made using an acrylic box, and the noise reduction effect was measured under four conditions. The experimental results are as follows: First, the soundproof panel had a noise reduction effect in all ranges from 55dB to 85dB. In the case of using a high-frequency vibration generator, there was no effect in the low noise range such as 55dB(A), but there was a noise reduction effect in the high noise range such as 70.8dB(A) and 85dB(A).Second, when the soundproof panel and the high-frequency vibration generator were used simultaneously, the noise reduction effect was up to -2.2dB(A). The results of this experiment were obtained from an experimental model made of acrylic, and they may be different from actual ships made of steel plate. In future studies, we plan to experiment using iron plate (considering the material, thickness, and structure) used in actual ships. We hope that this study will help to improve the living environment and health of seafarers on ships.

도로 소음 저감을 위한 능동소음제어 시스템의 개발 및 기초실험

문학룡,강원평,임유진 한국도로학회 2013 한국도로학회논문집 Vol.15 No.6

PURPOSES: The purpose of this study is about noise which is generated from roads and is consist of irregular frequency variation from low frequency to various band. The existing methods of noise reduction are sound barrier that uses insulation material and absorbing material or have applied passive technology of noise reduction by devices. The total frequency band is needed to apply active noise control. METHODS: In this study applies to the field of road traffic environment, signal processing controller and various analog signal input/output, the amplifier module is based on parallel-core embedded processor designed. DSP performs the control algorithm of the road traffic noise. Noise sources in the open space performance of evaluation were applied. In this study, controller of active signal processor was designed based on the module of audio input/output and main controller of embedded process. The controller of active signal processor operates noise reduction algorithm and performance tests of noise reduction in inside and outside environment were executed. RESULTS : The signal processing controller with OMAP-L137 parallel-core processors as the center, DSP processors in the active control operations dealt with quickly. To maximize the operation speed of an object and ARM processor is external function keys and display for functions and evaluating the performance management system was designed for the purpose of the interface. Therefore the reduction of road traffic noise has established an electronic controller-based noise reduction. CONCLUSIONS : It is shown that noise reduction is effective in the case of pour tonal sound and complex tonal sound below 500Hz by appling to Fx-LMS.

도로 소음 저감을 위한 능동소음제어 시스템의 개발 및 기초실험

문학룡,강원평,임유진 한국도로학회 2013 한국도로학회논문집 Vol.15 No.6

PURPOSES: The purpose of this study is about noise which is generated from roads and is consist of irregular frequency variation from low frequency to various band. The existing methods of noise reduction are sound barrier that uses insulation material and absorbing material or have applied passive technology of noise reduction by devices. The total frequency band is needed to apply active noise control. METHODS: In this study applies to the field of road traffic environment, signal processing controller and various analog signal input/output, the amplifier module is based on parallel-core embedded processor designed. DSP performs the control algorithm of the road traffic noise. Noise sources in the open space performance of evaluation were applied. In this study, controller of active signal processor was designed based on the module of audio input/output and main controller of embedded process. The controller of active signal processor operates noise reduction algorithm and performance tests of noise reduction in inside and outside environment were executed. RESULTS : The signal processing controller with OMAP-L137 parallel-core processors as the center, DSP processors in the active control operations dealt with quickly. To maximize the operation speed of an object and ARM processor is external function keys and display for functions and evaluating the performance management system was designed for the purpose of the interface. Therefore the reduction of road traffic noise has established an electronic controller-based noise reduction. CONCLUSIONS : It is shown that noise reduction is effective in the case of pour tonal sound and complex tonal sound below 500Hz by appling to Fx-LMS.