• 한국산학기술학회논문지
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• 제21권11호
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• pp.617-623
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• 2020

다수의 승객을 운송하는 도시철도 전동차는 도시 철도교통시스템의 핵심이다. 따라서 차량의 동적성능이 확보가 차량 안전 확보 및 승객서비스 차원에서 선행되어야 한다. 철도차량의 진동, 승차감과 같은 동적거동은 현가시스템 구조 및 현가요소에 따라 크게 영향을 받는다. 철도차량의 현가시스템은 윤축과 대차간 1차현가시스템, 대차와 차체간 2차현가시스템으로 구성되어 있다. 본 논문에서는 국내에서 운용되고 있는 전동차 현가구조에 따른 전동차의 동적거동에 대하여 분석하고자 한다. 현가구조가 상이한 2종류의 전동차에 대하여 실제 선로에서 동일 주행조건으로 주행시험을 수행하였으며 차량의 진동을 계측하였고 진동과 승차감, 진동감쇠율과 같은 동적거동 특성을 분석하였다. 시험결과, 차체 진동성능은 좌우방향은 B대차가, 상하방향은 A대차가 상대적으로 우수하게 나타났다. 승차감은 전반적으로 A대차가 B대차에 비하여 우수하게 나타났다. 진동감쇠율을 보면, 1차현가시스템은 고무스프링이 적용된 A대차에 비하여 코일스프링이 적용된 B대차의 진동감쇠 성능이 우수하며 2차현가시스템은 코일스프링에 비하여 공기스프링이 적용된 A대차의 진동감쇠 성능이 우수하다. 본 논문의 결과는 향후 철도차량 신차 설계 과정에서 현가구조 설계 및 현가요소 선정 시, 유용한 자료로 활용될 것이라 기대된다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.497-502
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• 2008

In this paper, we studied on an attenuation effect of automobile exhaust noise according to the direction of secondary sound source in duct ANC system. Automobile exhaust noise was recorded at 800rpm. 3500rpm and 5000rpm of a diesel engine. Directions of loudspeaker(second sound source) can be exchanged to $30^{\circ}$, $90^{\circ}$ and $150^{\circ}$ against the primary noise flow by acrylic ducts to be made for experimentation. DSP board with TMS320C6416 chip of Texas Instrument Co used to control adaptive ANC system. This ANC system is based on the single-channel FxLMS algorithm. In experiment result, when the loud speaker direction was $150^{\circ}$, the attenuation effect showed largely. In case of $90^{\circ}$ duct, the noise was a little increased. In case of $30^{\circ}$ duct, the noise was a little increased or decreased according to the frequency range and the sound pressure(dB) of exhaust noise to comply with engine rpm.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1829-1835
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• 2000

The experimental results of sodium-water reaction noise measurement in frequency range $1{/sim}200kHz$ are presented. The experiments of noise generation under the condition of sodium test facility, water leak rate $0.01{\sim}1.2g/s$ and temperature of sodium $250{\sim}500^{\circ}C$, were carried out. From theoretical study it is noted that the noise resonant attenuation on hydrogen bubbles in liquid sodium plays the significant role for leak noise spectra formation. Interaction of leak noise and hydrogen bubbles in sodium being accompanied by thermal, emission and viscosity energy dissipation was studied. Acoustic noise spectra were investigated from point of view of water leak detection in sodium/water steam generator. The results of sodium-water reaction noise absorption on hydrogen bubbles in liquid sodium by temperature $250{\sim}500^{\circ}C$ are presented. The theoretical model of noise absorption using the coefficients of attenuation was developed. From calculation the coefficients of attenuation were estimated.

• 한국소음진동공학회논문집
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• 제19권3호
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• pp.251-260
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• 2009

In this paper, we studied on an attenuation effect of automobile exhaust noise according to the direction of canceling speaker in ANC system. Automobile exhaust noise was recorded at 800 rpm, 3500 rpm and 5000 rpm of a diesel engine. Directions of canceling speaker can be set to $30^{\circ}$, $90^{\circ}$ and $150^{\circ}$ against the primary noise flow by acrylic ducts to be made for the experimentation. DSP board with TMS320C6416 chip of Texas Instrument Co. used to control the ANC system. The algorithm of this ANC system applied the Filtered-x-LMS algorithm that is modified to compensate for a property of DSP input signal and the secondary-path effect. As an experiment result, the direction of canceling speaker was proved to influence the reduction effect of noise. The $150^{\circ}$ duct in the attenuation effect of noise showed a better result than the $90^{\circ}$ or $30^{\circ}$ duct.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.561-566
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• 2008

Recently, because of development of the high speed train technology, the vibration loads by train is significantly increased ever than before. This buried gas pipelines are exposed to both repeated impact loads, and, moreover, they have been influencing by vibration loads than pipeline which is not located under vehicle loads. The vibration characteristic of pipeline is examined by dynamic analysis, and variable is only train speed. Since an effect of magnitude of vibration loads is more critical than cover depth, as increasing the train speed, the vibration speed of buried pipelines is also increased. The slope of vibration velocity is changed by attenuation of wave, at train speed, 300 km/h. From the analysis results, the vibration velocity of pipelines is satisfied with the vibration velocity criteria which are established by Korea Gas Corporation. The results present operation condition of pipelines under rail loads has fully sound integrity based on KOGAS specification.

• 소음진동
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• 제8권4호
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• pp.733-740
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• 1998

본 논문은 덕트 내에 설치된 음향 스크린의 특성을 연구하였다. 다양한 형상의 음향 스크린의 투과 손실 측정을 통하여, 음향 스크린에 의해 생긴 두 개의 비대칭 경로가 특정 주파수에서 큰 협대역 소음 저감을 발생시킴을 알 수 있었다. 그리고, 실험과 수치적 모의 실험을 바탕으로 이러한 현상을 정확하게 설명할 수 있는 해석적 모델을 개발하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.1032-1037
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• 2003

This work measured the hand-transmitted vibration due to shipyard worker's grinding and assessed the vibration exposure for predicted 10% prevalence of vibration-induced white finger in a group of exposed persons according to test procedure of ISO 5349-1. And also the transmissibility performance of resilient material, mainly applied to anti-vibration gloves in present market was measured on the basis of ISO 13753 and confirmed that the material would Probably not provide greater attenuation below 30㎐, the dominant frequency range of hand-transmitted vibration due to grinder.

• 한국소음진동공학회논문집
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• 제11권4호
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• pp.71-77
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• 2001

In this paper, stress wave propagation characteristics of MR(Magneto-rheological) inserts are experimentally investigated. Generally, stress waves of structures such as warships or submarines are induced by shock waves from underwater explosion. Their fatal effects on the shipboard equipments or structures damage the performance of warships. But, such a problem can be solved by controlling the stress waves propagating through structures by means of MR inserts. MR insert consists of two aluminum layers and MR fluid filled in between. Two piezoceramic disks are embedded on the host plate as a transmitter and a receiver of stress waves. Pulse waves are generated by the transmitter and they reach to the receiver through the MR insert. Permanent magnet and magnetic coil are used to produce magnetic field at the MR insert. In the presence of magnetic field, MR particles are arranged in chains parallel to the magnetic field such that the transmitted stress waves are reduced. Attenuation of stress waves is experimentally investigated.

• 한국소음진동공학회논문집
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• 제12권6호
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• pp.413-419
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• 2002

Noise barriers are widely used to reduce the sound level propagating from highways, railways or factories to residential areas. The reduced noise level at a receiver point is then determined by the diffracted waves around the edge of the barrier as well as by the transmitted waves through the barrier. 1'or proper usage, many studies either theoretical or experimental have been made with the objective of precisely Predicting the acoustic field and improving the noise attenuating properties of barriers. In this study. a simple scattering model. a line acoustic source scattered by an infinite cylinder, is introduced to simply Investigate the sound attenuation efficiency of a sound-resonating barrier. From this model study, it is observed that the sound-resonating harrier can be used as a good sound-shielding element especially for the pure-tone noise generated from the transformer. Large sound-attenuation is achieved by applying the sound-resonating barrier to the large transformers in a substation.

• 한국소음진동공학회논문집
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• 제20권9호
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• pp.816-821
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• 2010

The paper presents a theoretical analysis on the propagation characteristics of the high-frequency wave in an elastic waveguide whose diameter is less than or similar to the wavelength. The theoretical results were verified by comparing them with the numerical results obtained by the boundary-element method. The ratio of the waveguide diameter to the wavelength affects the number of the existing wavenumber, and thus it affects the propagation characteristics. In the media with attenuation, the trend is similar to that in the media without attenuation except the decreasing amplitude.