• Title/Summary/Keyword: Vibration %26 Noise

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Development of the Anti-vibration Base for the Onboard Equipment of the Naval Vessel Using Sandwitch Panel (샌드위치 패널을 이용한 함정탑재장비용 방진 베이스 개발)

  • Han, HyungSuk;Lee, KyoungHyun;Park, SungHo;Wi, YangHyun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.26 no.4
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    • pp.365-374
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    • 2016
  • The underwater radiated noise can be reduced by decreasing the structure borne noise of the on-board equipment. Therefore, the structure borne noise of the onborad installed equipment is strongly restricted by ROK navy with MIL-Std 740-2. Usually, the vibration transmissibility from the equipment to the hull of the ship is dependent on its mount characteristics. Even though the double mount structure is proper to apply for ship board application rather than single mount, it is not widely applied due to the weight and volume resriction of the ship. Therefore, in this research, the base using sandwitch panel which can act as double mount structure is suggested and its noise reduction capacity is verified with analytic calculation as well as experiment.

Noise-source Analysis of Tactical Vehicle Using Partial Coherence Function (부분기여도함수를 이용한 전술차량 소음원 분석)

  • Park, Sungho;Lee, Kyunghyun;Han, HyungSuk;Jeon, Soohong
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.26 no.7
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    • pp.774-780
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    • 2016
  • In this paper noise source and transfer path of tactical vehicle are analyzed with partial coherence function and spectrum analysis. Engine, transmission, structure panel and aerodynamic are main source of cabin noise. To reduce cabin noise, identifying transfer path of sources and analyzing their contribution is important. With modeling of transfer path and partial coherence function, transfer path and principal noise source can be identified. Engine/transmission and structural resonance are principal source of low frequency noise and by adding stiffener and sound absorbing material, resonance of vibration and inflow air problem can be solved.

Beam Vibration Suppression with Translational and Rotational Damped Dynamic Vibration Absorbers (병진 및 회전 감쇠동흡진기를 사용한 보의 진동저감)

  • Park, Sung Gyu;Lee, Shi Bok
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.26 no.6_spc
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    • pp.721-728
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    • 2016
  • The combined rotational and translational dynamic vibration absorbers (DVA) with no dampers for the beam vibration control can effectively isolate the vibration within the external excitation force region. This paper investigates the damping efficacy for the combined rotational and translational dynamic vibration absorbers to impose some robustness to the DVA system for the excitation force frequency variation. The beam is assumed to be subjected to a concentrated harmonic excitation force. The solution to the problem is found based on Galerkin method.

Contribution Analysis to Identify the Source of Ship Hull Vibration (선체 진동 특성 규명을 위한 기여도 분석)

  • Lee, Jun Woo;Ahn, Se Jin;Oh, Jun Seok;Kim, Tae Hyeong;Jeong, Weui Bong
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.26 no.5
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    • pp.528-535
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    • 2016
  • The vibration of a ship gives a significant effect on the noise radiated into the water. This paper focused on the vibration of ship hull due to the sub-generator located on the deck in the anchored condition. The contributions of the transfer paths between sub-generator and ship hull were analyzed using the TPA and the OTPA method. While the sub-generator was operation and the main engine was turned off, the vibrations were measured simultaneously at the 38 locations of the ship and the one hydrophone was arranged to measure the underwater radiated noise at the overside ship. The results of the transfer path by applying TPA and OTPA were compared and discussed. As a result of these methods, the top of stovepipe and valve are contributive. Reinforcing these structures is the most effective to reduce the vibration of ship hull.

Study on the Reduction Method of Magnetic Noise and Vibration in Home Electric Motors (가전기기용전동기의 전자소음과 진동의 방지대책에 관한 연구)

  • 황영문;조철제
    • 전기의세계
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    • v.26 no.5
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    • pp.74-82
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    • 1977
  • This study is to present a method for reductin of noise and vibration of home electric motors coupled to the mechanical load causing relatively big amplitude of vibration. The noise and vibration factors have been analysed in the divisions such as the pattern related to the armature reaction, the pattern related to the circulating current by induction and the other patterns those are affected by a dditive magnetic field and have an effect on mechanical constants. From the systematic mutual relations between the patterns and daping effects, it is possible to derive the fundamental measure for reduction of noise and vibration. Vibration measurements and analysis were carried out in accordance with the planned experimentation and thre object model was chosen randomly from the production line in a factory where home electric machines were mass-produced. Based on the above-mentioned fundamental measure, suppression effects on noise and vibration have been analysed according to the number of slots, the amount of rotor skew and the way the stator winding connection was series or parallel.

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Experimental Analysis about Influence Parameters at the Propagation of Large Arm’s Firing Noise (대구경 사격소음 전달 영향인자에 대한 실험적 분석)

  • Kim, Eung-Su
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.26 no.4
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    • pp.412-419
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    • 2016
  • The firing noise produced at artillery test range or military training ground is impulsive burst noise which energy is generated within tens of milliseconds and distributed an isolated burst of sound energy separated to one by one noise. The long range propagation of this noise is affected by a caliber of gun, amount of propellant, distance between source and receiver, ground and meteorological condition. In this paper, main influence parameters have been described based on experimental analysis of measured data. It is considered that this analysis result can be used as useful materials for study of effective firing noise management and development of propagation model.

Experimental Study on Vibration Reduction Estimation of PRD Pile Driving Method (PRD Pile Driving공법의 진동저감 평가를 위한 실험적 연구)

  • Kang, Sung-Hoo;Park, Sun-Joon;Jung, Seok-Gyu
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.7
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    • pp.775-782
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    • 2008
  • In this study, ground vibrations and aero space noises that is produced by the PRD(percussion rotary drill) were analyzed by work processes. Ground vibration equations were suggested by $2.798(SD)^{-0.793}$, $3.485(SD)^{-0.793}$, $3.705(SD)^{-0.793}$, according to experiment result, and these equations have reliability of 50%, 90%, 95%, respectively. Ground vibration values by the PRD method correspond to level of $5{\sim}34%$ of values that are assumed by the Attewell & Farmer's equation, and these result compares in reliability 50%. Also, those values were analyzed that correspond to level of $12{\sim}26%$ of ground vibration values by the Prof. Park etc.'s equations. But, the aero space noise was evaluated that is assumed by 88.9 dB(A) at separated distance 50m and is not satisfied even 85dB(A) that is the most negative noise value that present in domestic noise standard. The PRD method was analyzed that noise decrease effect exists hardly comparing with general pile driving method of construction. When is based in these results, the PRD method is judged that it is desirable that classify by the Low-vibration method more than the Non-violation noise method.

Sound Quality Study and its Application to Car Interior and Exterior Noise

  • Hashimoto, Takeo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.19-26
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    • 2001
  • There passed almost 15 years since our sound quality studies in Japan related to the emitted noise from the industrial products have been started. The sound under consideration are interior and exterior noise from cars, noise from the electric appliances such as electric shavers, electric cleaners and washing machines and the sound emitted from earth moving machines and etc. After a little while since sound quality studies have been started, the products with better sound are gradually on sale on the market.

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Study on Performances of the Lever Type Anti-resonance Vibration Isolator (레버형 반공진 진동 절연기의 진동 특성 연구)

  • Yun, Jong-Hwan;Kim, Gi-Woo;Lee, Hyeongill
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.26 no.2
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    • pp.187-194
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    • 2016
  • Parametric study on the lever type dynamic anti-resonance vibration isolator (DAVI) is executed to introduce the system in the path of vibration transmission for the vibratory response attenuation. The effects of inertia and location of the lever on the system performances are investigated using FEA. The effects of other parameters such as ratio of lever lengths, ratio of masses and the location of pivot are studied with analytical approach. According to the results, all the parameters except lever location affect the system response in their own ways. Consequently, the optimal lever type DAVI for translational or rotational system can be efficiently designed by selecting system parameters using the procedure introduced in this study.