• Title/Summary/Keyword: Noise Current

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A Study on the Noise and Vibration Characteristics during Construction of Screw Concrete Pile for Reduction of Noise and Vibration (소음 및 진동 저감을 위한 스크류콘크리트말뚝의 시공 중 소음과 진동 특성에 관한 연구)

  • Kim, Dongchul;Choi, Yongkyu
    • Journal of the Korean GEO-environmental Society
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    • v.14 no.9
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    • pp.21-30
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    • 2013

  • Because the noise and vibration regulations in domestic areas are being tightened more and more, a more environmentfriendly method than the current low-noise & low-vibration methods is needed. In this study, the characteristics of screw concrete piles for reduction of noise and vibration were explained, and during pilot tests the noise and vibration were measured. The measured vibration value is satisfied with the vibration regulations at 7.5m distance from the source. The measured noise value is exceeded over about 2dB(A) at the 15.0m distance from the source but these values are about 5~20dB(A) less than the measured values of the current low-noise & low-vibration method.

  • KSCI

A study on the Conducted Noise Reduction in Random PWM (Random PWM 기법을 이용한 전도노이즈 저감)

  • Jeong, Dong-Hyo
    • Proceedings of the KIEE Conference
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    • 2006.10b
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    • pp.154-158
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    • 2006

  • The switching-mode power converter has been widely used because of its features of high efficiency and small weight and size. These features are brought by the ON-OFF operation of semiconductor switching devices. However, this switching operation causes the surge and EMI(Electromagnetic Interference) which deteriorate the reliability of the converter themselves and entire electronic systems. This problem on the surge and noise is one of the most serious difficulties in AC-to-DC converter. Random Pulse Width Modulation (RPWM) is peformed by adding a random perturbation to switching instant while output-voltage regulation of converter is performed. RPWM method for reducing conducted EMI in single switch three phase discontinuous conduction mode boost converter is presented. The more white noise is injected, the more conducted EMI is reduced. But output-voltage is not sufficiently regulated. This is the reason why carrier frequency selection topology is proposed. In the case of carrier frequency selection, output-voltage of steady state and transient state is fully regulated. A RPWM control method was proposed in order to smooth the switching noise spectrum and reduce it's level. Experimental results are verified by converter operating at 300v/1kW with $5%{\sim}30%$ white noise input. Spectrum analysis is performed on the Phase current and the CM noise voltage. The former is measured with Current Probe and the latter is achieved with LISN, which are connected to the spectrum analyzer respectively.

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Pantograph-catenary Dynamic Interaction for a Overhead Line Supported by Noise Barrier

  • Belloli, Marco;Collina, Andrea;Pizzigoni, Bruno
    • International Journal of Railway
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    • v.5 no.2
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    • pp.55-64
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    • 2012

  • Subject of the paper is a particular configuration of overhead line, in which noise barrier structure is used as supports of the catenary instead of standard poles. This configuration is foreseen in case the noise barrier position is in conflict with the poles location. If the catenary is supported by the noise barrier, the motion that the latter undergo due to wave pressure associated to train transit is transmitted to the overhead line, so that potentially it influences the interaction between the catenary itself and the pantograph of the passing train. The paper focuses on the influence of such peculiar configuration on the quality of the current collection of high speed pantograph, for single and double current collection. The study has been carried out first with an experimental investigation on the pressure distribution on noise barrier, both in wind tunnel and with in-field tests. Subsequently a numerical analysis of the dynamics of the barrier subjected to the wave pressure due to train transit has been carried out, and the output of such analysis has been used as input data for the simulation of the pantograph-dynamic interaction at different speeds and with front or rear pantograph in operation. Consideration of structural modifications was then highlighted, in order to reduce the influence on the contact loss percentage.

  • https://doi.org/10.7782/IJR.2012.5.2.055 인용 PDF