• Title/Summary/Keyword: control vibration

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Characteristics of vehicle mufflers and improvement measures of vehicle exhaust noise (자동차 소음기 특성 및 배기소음 개선 방안)

  • Lee, Jae-Won;Kang, Dae-Joon;Gu, J.H.;Park, H.K.;Kim, T.S.;Kweon, H.J.;Kim, J.C.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.897-900
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    • 2007
  • Vehicles are exhausting various environmental pollutions such as exhaust gas, noise, and so on. This study investigates only noise problems by vehicles, especially the vehicle exhaust noise. It is known that the exhaust noise among those is over 20% of vehicle noise when the vehicle is suddenly accelerated or normally accelerated. In this study, we mainly investigate the exhaust noise of vehicle so that we intend to show the measures to decrease the illegal tuning mufflers and reduce the exhaust noise problems. In the conclusion, we suggest the new appropriate standard to control the tuning mufflers and reduce the exhaust noise induced by vehicles.

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Study on method of build up low-frequency diffuse sound field in a scaled reverberation chamber (축소잔향실의 저주파수 확산음장 형성 방법에 대한 연구)

  • Kang, Jun-Goo;Kang, Hyun-Ju;Kim, Sang-Ryul;Choi, Jong-Soo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.61-64
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    • 2007
  • This study is dealt with a method to enhance low-frequency diffuse sound field in a scaled reverberation chamber. Because scaled reverberation chamber has not enough room volume, as a result, it shows a few room modes. So it is not build up low-frequency diffuse sound field. A Helmholtz resonator's arrangement is used to improve spatial uniformity of sound pressure at low frequency. The spatial distribution of sound field has been measured before and after control. The standard deviation of sound field has decreased at 315Hz 1/3 Octave band.

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Optimal design of tuned mass damper considering the friction between the moving mass and the rail (레일의 운동마찰력을 고려한 TMD 최적 설계)

  • Lee, Sang-Hyun;Woo, Sung-Sik;Cho, Seung-Ho;Chung, Lan
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.582-587
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    • 2007
  • In this study, based on the results from the sinusoidal base excitation analyses of a single degree of freedom system with a tuned mass damper (TMD), it is verified that optimal friction force can improve the performance of a TMD like a linear viscous damper which has been usually used in general TMD. The magnitude of the optimal friction increases with increasing mass ratio of the TMD and decreases with increasing structural damping. Particularly, it is observed that the optimized friction force gives better control performance than the optimized viscous damping of the TMD. However, because the performance of the TMD considerably deteriorates when the friction force increases over the optimal value, it is required to keep the friction force from exceeding the optimal value.

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Model Updating of an Equipment Panel with Embedded Heat Pipes (히트 파이프가 내장된 통신위성용 탑재체 패널의 해석모델 개선)

  • 양군호;최성봉;김흥배;문상무
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1998.04a
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    • pp.114-121
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    • 1998
  • This paper presents the model updating of an equipment panel by using modal test and sensitivity analysis. The equipment panel is one of the major structures of communication satellite, on which broadcasting and communication equipments are mounted. For high rigidity and light weight, the panel was designed as an aluminum honeycomb sandwich panel. In addition, heat pipes were embedded in the panel for thermal control. It is essential to improve the finite element model of a satellite by using modal test in order to verify the satellite is designed with adequate margin under launch environment. In this paper, Young's modulus of aluminum facesheet was selected as a modified parameter by sensitivity analysis. The effect of rotational springs of boundary points was also considered.

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Development and Performance of Automated Calibration System of Sound Level Meters (소음계 교정 자동화 시스템 개발 및 성능평가)

  • 김용태;조문재;이용봉;서재갑;서상준
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1998.04a
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    • pp.704-709
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    • 1998
  • An automated calibration system of sound level meters was developed and tested. As a standard sound source, the speaker unit(Forstex FE208) cabineted by 440 * 390 * 490 mm$^{3}$(LHW) volume wood box was adopted. Including this source, the driving part was found out to have a good linearity of sound pressure output vs AC input. We use the Hybrid-Bisect, /Newton-Raphson method modified by the linearity as searching algorithm. Personal computer and program do the control, measurements, and calculations and finally do the accumulation of useful data and results. Several trials of automatic calibration using this developed system give reliable results.

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An Experimental Study of the Effects of Water Vapor in Intake Air on Comvustion and knock Characteristics in a Spark Ignition Engine (흡기중 수증기 함량이 스파크 점화기관의 연소 및 노킹에 미치는 영향에 관한 실험적 연구)

  • 이택헌;전광민
    • Transactions of the Korean Society of Automotive Engineers
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    • v.6 no.1
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    • pp.205-212
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    • 1998
  • In this study, the effects of water vapor in inlet air on combustion efficiency, general performance, knock characteristics and emission gas concentration were investig- ated through the experiments of combustion and vibration analyses, emission gas analysis by changing water vapor quantity in inlet air with temperature and humidity auto control unit. With partial vapor pressure increase, the brake torque at wide open throttle status decreased and the average ignition delay angle increased, IMEP (indicated mean effective pressured using the integral and 3rd derivatives of filtered cylinder pressure as knock intensity, which matched well with the method of frequency power spectrum of block vibration signal. Water vapor in intake air had influence on the spark knock sensitivity. With the increase of water vapor content in intake air NOx emission was decreased and HC emission was increased.

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Fan Case Design using Energy Conversion Ideal Function Based Taguchi Dynamic Characteristics (에너지 전환 이상기능 기반 다구찌 동특성을 활용한 Fan Case 설계)

  • Ji, Soo Yoon;Jang, Joong Soon
    • Journal of Korean Institute of Industrial Engineers
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    • v.41 no.1
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    • pp.97-104
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    • 2015
  • An electric-motor which uses electric energy to dry laundry in a dryer generates wind by rotating a fan. The roles of electric motor and fan are crucial for drying. To reduce the noises or vibration, their performances should be improved. However, it requires a relatively high cost to redesign them. In this case, redesigning the fan case rather than the motor or the fan would be easier and cheaper. This paper is to apply Taguchi dynamic characteristic concept with the ideal function of energy conversion to redesign the fan case. Not only the increase of the wind power but also the decrease of noise, vibration and the other side effects are resulted.

Design of Compact Magneto-Rheological Fluid Damper for Artificial Low-Limb Prosthesis (Magneto-Rheological Fluid를 이용한 인공지능 의족의 Compact damper 개발)

  • Sung, So-Young;Kang, S.J.;Moon, I.H.;Moon, M.S.;Jang, S.M.
    • Proceedings of the KIEE Conference
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    • 2005.07d
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    • pp.2962-2964
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    • 2005
  • Magneto-Rheological (MR) fluid is suspension of fine magnetic particles in a liquid carrier such as silicon oil or water. MR fluid exhibits solid-like mechanical behavior into chain or clusters with high yield stress when magnetic field is applied to the particles. The response of MR fluids is very quick and reversible after removal of the field. MR Fluids have high yield stress (up to 5kPs) and operate in low voltage power supply. Recently, MR damper using MR fluids was open used in vibration control system such as structural devices, seat vibration controllers and helicopter rotor systems, but it is too big in size and heavy. Therefore, it is not appreciate to rehabilitation devices such as prosthetic limbs.

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Sensible Media Simulation in an Automobile Application and Human Responses to Sensory Effects

  • Kim, Sang-Kyun;Joo, Yong-Soo;Lee, YoungMi
    • ETRI Journal
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    • v.35 no.6
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    • pp.1001-1010
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    • 2013
  • A sensible media simulation system for automobiles is introduced to open up new possibilities for an in-car entertainment system. In this paper, the system architecture is presented, which includes a virtuality-to-reality adaptation scheme. Standard data schemes for context and control information from the International Standard MPEG-V (ISO/IEC 23005) are introduced to explain the details of data formats, which are interchangeable in the system. A sensible media simulator and the implementation of a sensory device are presented to prove the effectiveness of the proposed system. Finally, a correlation between learning styles and sensory effects (that is, wind and vibration effects) is statistically analyzed using the proposed system. The experiment results show that the level of satisfaction with the sensory effects is unaffected overall by the learning styles of the test subjects. Stimulations by vibration effects, however, generate more satisfaction in people with a high tactile perception level or a low visual perception level.

Effects of sound-masking on the soundscape of urban public spaces with multiple noises (복합소음 공간의 Soundscape에 대한 사운드 마스킹의 효과)

  • Jeong, Choong-Il;You, Jin;Lee, Pyoung-Jik;Jeon, Jin-Yong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.04a
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    • pp.268-271
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    • 2008
  • A sound-masking technique was applied to the urban public spaces with multiple noises in order to reduce the annoyance of the construction and traffic noise. In addition, the effects of masking system were investigated in order to improve the soundscape. In several urban spaces, building construction and nearby road traffic noise were recorded using a head and torso simulator and sound quality (SQ) system which specifies the spectral and temporal aspects of the noises. The sound-masking system which consists of the distributed speakers and control devices was applied to the boundaries of the construction sites. Synthesized masking sounds were produced with consideration of SQ characteristics of the multiple noise. Subjective evaluations on the soundscape were conducted to verify effectiveness of the system under the conditions with and without the masker sounds.

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