• Title/Summary/Keyword: Noise Reduction Technology

Search Result 610, Processing Time 0.029 seconds

The properties of noise and vibration in Whirlpool bath and plan for its reduction (공동주택 월풀욕조의 소음진동 특성 및 저감 방안)

  • Bae, Sang-Hwan;Lee, Byung-Kwon
    • Proceedings of the SAREK Conference
    • /
    • 2005.11a
    • /
    • pp.506-510
    • /
    • 2005
  • This study shows work on the properties of noise and vibration in Whirlpool bath and plan for its reduction. Totally through 3 steps. we found out the properties of noise and vibration. various anti-vibration design for an effeciency test is conducted. By Anti-vibration for the pump causing vibration, about 4dB(A) was reduced. Moreover. by anti-vibration construction fixing the bathtub frame. about 3db(A) could be reduced. In the case of anti-vibration construction about the wall around the bathtub. and spreading damping paint on the bathtub. the noise was reduced.

  • PDF

Technology Trend of Vibration/Noise Active Control in Helicopter (헬리콥터 능동 진동/소음 제어 기법 해외 동향 및 사례)

  • Kim, Deog-Kwan;Yun, Chul-Yong;Chung, Ki-Hoon;Kim, Seung-Ho
    • Current Industrial and Technological Trends in Aerospace
    • /
    • v.9 no.1
    • /
    • pp.77-89
    • /
    • 2011
  • The vibration and noise reduction issue is very important in helicopter since the thrust and flight control force of helicopter are generated by rotating drive system. In past, there was a passive method to reduce vibration and noise to focus on specified frequency. Now, there are various active method to reduce vibration and noise due to technology development. This paper describes the worldwide technology trend of vibration and noise active control in helicopter. At introduction, generalmethod of vibration and noise reduction.

  • PDF

Experimental study of noise level optimization in brain single-photon emission computed tomography images using non-local means approach with various reconstruction methods

  • Seong-Hyeon Kang;Seungwan Lee;Youngjin Lee
    • Nuclear Engineering and Technology
    • /
    • v.55 no.5
    • /
    • pp.1527-1532
    • /
    • 2023
  • The noise reduction algorithm using the non-local means (NLM) approach is very efficient in nuclear medicine imaging. In this study, the applicability of the NLM noise reduction algorithm in single-photon emission computed tomography (SPECT) images with a brain phantom and the optimization of the NLM algorithm by changing the smoothing factors according to various reconstruction methods are investigated. Brain phantom images were reconstructed using filtered back projection (FBP) and ordered subset expectation maximization (OSEM). The smoothing factor of the NLM noise reduction algorithm determined the optimal coefficient of variation (COV) and contrast-to-noise ratio (CNR) results at a value of 0.020 in the FBP and OSEM reconstruction methods. We confirmed that the FBP- and OSEM-based SPECT images using the algorithm applied with the optimal smoothing factor improved the COV and CNR by 66.94% and 8.00% on average, respectively, compared to those of the original image. In conclusion, an optimized smoothing factor was derived from the NLM approach-based algorithm in brain SPECT images and may be applicable to various nuclear medicine imaging techniques in the future.

RFID Noise Reduction Using a Multi-Coil Antenna (다중 코일 안테나를 이용한 RFID 유도 잡음의 감소)

  • Lee, Seong-Ho
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.19 no.6
    • /
    • pp.603-611
    • /
    • 2008
  • In this paper, we introduce a multi-coil antenna which is useful for reducing the effects of radio frequency noise in an inductively coupled RFID system. A multi-coil antenna is composed of a central coil and four subsidiary coils that are connected in series. A multi-coil antenna is designed so that the total noise disappear when the induced voltages of a central coil and subsidiary coils are added. The noise in a multi-coil antenna was about 30 dB lower than that in a single coil antenna. The multi-coil antenna is very effective in noise reduction even in an environment that the spatial distribution of RF noise is changed abruptly, and the induced noise was about 16 dB lower than that in a dual coil antenna.

Design and Software Implementation of Noise Reduction Filter for Mid-wave Infrared Images (중적외선 영상 잡음 감소를 위한 SW 필터의 설계 및 구현)

  • Park, Hyunsung;Kim, Jungho;Lee, Sungho
    • Journal of the Korea Institute of Military Science and Technology
    • /
    • v.19 no.4
    • /
    • pp.500-507
    • /
    • 2016
  • In order to increase the survivability of combatant ship, measuring and analyzing the infrared radiation is important. Consequently, providing analysis report is also important for the progress of the new combatant ship design. This paper proposes a design and software implementation of filtering for the noise reduction of mid-wave IR camera image. We reduced the total test cost by using the suggested software filtering technique instead of hardware replacement or re-calibration. In addition, we enhanced the accuracy of analysis results by adjusting the parameters of software filtering according to the results of filtered image.

Speckle Noise Reduction and Edge Enhancement in Ultrasound Images Based on Wavelet Transform

  • Kim, Yong-Sun;Ra, Jong-Beom
    • Journal of Biomedical Engineering Research
    • /
    • v.29 no.2
    • /
    • pp.122-131
    • /
    • 2008
  • For B-mode ultrasound images, we propose an image enhancement algorithm based on a multi-resolution approach, which consists of edge enhancing and noise reducing procedures. Edge enhancement processing is applied sequentially to coarse-to-fine resolution images obtained from wavelet-transformed data. In each resolution, the structural features of each pixel are examined through eigen analysis. Then, if a pixel belongs to an edge region, we perform two-step filtering: that is, directional smoothing is conducted along the tangential direction of the edge to improve continuity and directional sharpening is conducted along the normal direction to enhance the contrast. In addition, speckle noise is alleviated by proper attenuation of the wavelet coefficients of the homogeneous regions at each band. This region-based speckle-reduction scheme is differentiated from other methods that are based on the magnitude statistics of the wavelet coefficients. The proposed algorithm enhances edges regardless of changes in the resolution of an image, and the algorithm efficiently reduces speckle noise without affecting the sharpness of the edge. Hence, compared with existing algorithms, the proposed algorithm considerably improves the subjective image quality without providing any noticeable artifacts.

Study on Development of air-passing soundproofing panel (통풍형 방음벽 개발에 관한 연구 I)

  • Yoon, Je-Won;Sim, Sang-Deok;Kim, Young-Chan;Ku, Bon-Sung;Eom, Joo-Yong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2011.04a
    • /
    • pp.638-643
    • /
    • 2011
  • The aluminum soundproofing panel used to the traffic noise reduction will judge with the material to improve because the CO2 emission is greater than other soundproofing panel such as plastic soundproofing panel. Also, if the air-passing soundproofing panel which can endure the fast wind velocity will be developed, it judged that it can reached to the target of low CO2 traffic technology development using the reduction of material cost and the lower consumption of steel. The objective of this study is to improve the soundproofing panel and to develop the air-passing soundproofing panel for the replacement of aluminum sound proofing panel which is more emit CO2 than other soundproofing panel. And, we tried to develop the reduction technology of CO2 emission through the development of air-passing soundproofing panel. At first, the flow and noise simulation were conducted for the purpose of the calculation of wind pressure on soundproofing wall and noise exposure level on receiver points according to the open ratio of air-passing soundproofing panel. And the 1st and 2nd mockup of air-passing soundproofing panel were made, and the design load test were conducted for these mockup.

  • PDF

Structural Modification for the Reduction of Radiation Noise of a Powertrain Based on CAE Technology (CAE를 이용한 파워트레인의 방사소음 저감을 위한 구조변경)

  • Song, Min-Keun;Oh, Ki-Seok;Lee, Sang-Kwon
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.18 no.4
    • /
    • pp.439-447
    • /
    • 2008
  • One of the key elements in efforts to minimize noise radiation from a powertrain is the knowledge of the main radiating component and the relation between the surface vibration of a powertrain and the sound pressure. In this research, the powertrain model is developed based on FEM(finite element method). This model is applied to the prediction of the vibration of a powertrain by using ADAMS and the radiation noise by using BEM(boundary element method). According to this numerical analysis, the surface vibration of a powertrain is investigated as a source of radiated noise. This surface vibration is caused by the 1st order natural vibration of the cylinder block and its mode shape is the torsion mode. Therefore, this mode shape is modified to reduce the surface vibration of the powertrain. The radiation noise of the modified powertrain is also reduced to $5{\sim}12\;dB$. This modification is very successful for the noise reduction based on the CAE technology.

Modeling of a Rotor System Incorporating Active Tab and Analysis of BVI Noise Reduction Characteristics (능동 탭 로터 모델링 및 BVI 소음 저감 특성 해석)

  • Kim, Do-Hyung;Kang, Hee Jung;Wie, Seong-Yong;Kim, Seung-Ho
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.41 no.11
    • /
    • pp.855-864
    • /
    • 2013
  • Active tab is one of the promising technology for the BVI (blade-vortex interaction) noise reduction, and analysis of noise reduction performance is very important phase of the technology development. For the purpose of analysing the performance of noise reduction using active tab, CAMRAD II model for a model-scale rotor system was constructed utilizing structural design result and airfoil aerodynamic data generated by CFD (computational fluid dynamics) calculation. HHC strategy was applied to descent flight condition and air-load was calculated by CAMRAD II then variations of BVI noise was calculated by in-house program. Calculation result with respect to tab length and control phase changes showed BVI noise could be reduced by -3.3dB.

A Study on the Soundproofing Plate Techniques for Noise Reduction of Power Transformers (전력용 변압기 소음저감을 위한 차음판 기술에 관한 연구)

  • Kweon, Dong-Jin;Koo, Kyo-Sun;Kim, Jung-Chon;Kim, Jin
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.22 no.12
    • /
    • pp.47-55
    • /
    • 2008
  • According to the increase of power demand and expansion of downtown, it is necessary to install transformers additionally in operating substations and construct substations in residential area. But the public complaint has been increased due to the transformer noise of the substation. KEPCO has used a vibration preventing pad, various soundproof walls and an enclosure to transformers in outdoor substations, and a soundproof door, shutter and wind-path soundproof equipment in indoor substations to block the sound propagation from the transformers. But these noise reduction methods are not satisfied. It should be considered to reduce transformer noise itself. To shut out sound emitted from transformers, we developed a soundproof technology that wall up reinforcing bar by steel sheet. For the practical application of it, we analyzed the vibration characteristics of a transformer tank and reduction of noise according to soundproof plate. As a result, it is confirmed that the technology can reduce 11 [dB] of transformer noise.