• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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• pp.627-632
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• 2003

Squeal noise is generated by railway vehicles transversing tight curves. This squeal has always been noticed as one of the most disturbing noise sourecs of railway systems. At present we cannot predicted squeal noise that is influenced by a large number of dependent parameters. But the application of wheel damping and rail lubrication have successfully reduced wheel squeal. In this study, we measured squeal noise to find out the reduction effectiveness of noise through rail lubricator.

• 한국철도학회논문집
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• 제16권3호
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• pp.175-182
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• 2013

전동 소음은 철도의 주요한 소음 중 하나이며, 차륜과 레일의 음향 조도에 의해 차륜 및 레일이 진동하면서 발생한다. 이러한 전동 소음의 저감 대책을 수립하기 위해서는 관련 인자들의 영향을 파악할 수 있는 예측모델이 필요하다. 본 논문에서는 차륜과 레일의 진동 특성을 이용해 전동 소음을 예측하기 위한 모델링에 관해 다루었다. 슬라브 도상 궤도에 대하여 1단 이산 탄성 지지 구조를 가진 보로 모델링 하였으며, 차륜 진동은 유한요소법을 이용한 수치해석을 적용하였다. 수직 및 수평방향 차륜-레일 집촉력들의 연성은 선형 Hertzian 접촉이론으로 모델링 하였고, 차륜과 레일의 진동 응답을 계산한 후 방사되는 소음을 예측하였다. 예측 모델의 신뢰성을 검증하기 위하여 시험차량에 대해 전동 소음을 측정하였다. 예측치가 측정치와 잘 일치하였으며, 특히 전동 소음이 주요하게 기여하는 200~4000Hz 주파수 대역에서 유사한 경향으로 나타남을 확인하였다.

• 한국음향학회지
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• 제18권1호
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• pp.32-37
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• 1999

철도소음·진동은 철도변에 거주하는 인근 주민들에게 커다란 불만족 인자로 등장하고 있다. 특히, 철도소음은 철도변에 거주하는 주민들에게 정신적, 심리적, 육체적으로 심각한 영향을 미치고 있으며 이로인해 철도변에 거주하는 주민들은 많은 괴로움을 호소하고 있는 실정이며, 특히 본 설문조사 결과 철도변 주민들은 경제적인 보상보다는 쾌적한 주거환경에 더 많은 관심을 가지고 있는 것으로 나타났다. 그럼에도 불구하고 국내의 경우 철도소음에 대한 심각성은 인식하고 있지만 구체적인 자료의 축적 및 연구가 이루어지지 않아 효율적인 대책수립이 매우 어려운 실정이다. 이러한 관점에서 본 연구에서는 철도변 주민들을 대상으로 설문조사를 실시하여 철도소음의 실태 및 영향을 파악해 보았으며, 이를 토대로 향후 효율적인 철도소음의 대책수립 및 철도소음에 대한 세부적인 기준설정을 위한 기초적인 자료를 제시하고자 한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.337.2-337
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• 2002

When vehicle travelling along the track which has irregularity such as vortical profile, dynamic forces arise at the Wheel/Rail contact patch by wheel/rail interaction. In particular short wavelength irregularities on dipped joint and small stiffness of connecting rail bring about intense wheel/rail dynamic effects at higher speed. In the paper, a new model for dipped joint rail is developed to study dynamic behavior of track. (omitted)

• 전기학회논문지
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• 제59권2호
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• pp.355-358
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• 2010

As CMOS technology continues to scale down, signal processing is favorably done in the digital domain, which requires Analog-to-Digital (A/D) Converter to be integrated on-chip. This paper presents a design methodology of 12-bit 1-MS/s Rail-to-Rail fully differential SAR ADC using Deep N-well Switch based on binary search algorithm. Proposed A/D Converter has the following architecture and techniques. Firstly, chip size and power consumption is reduced due to split capacitor array architecture and charge recycling method. Secondly, fully differential architecture is used to reduce noise between the digital part and converters. Finally, to reduce the mismatch effect and noise error, the circuit is designed to be available for Rail-to-Rail input range using simple Deep N-well switch. The A/D Converter fabricated in a TSMC 0.18um 1P6M CMOS technology and has a Signal-to-Noise-and-Distortion-Ratio(SNDR) of 69 dB and Free-Dynamic-Range (SFDR) of 73 dB. The occupied active area is $0.6mm^2$.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.570-573
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• 2004

Conventional methods for reducing vibration in engineering designs may be undesirable in conditions where size or weight must be minimized, or where complex vibration spectra exist. Some alloys with a combination of high damping capacity and good mechanical properties can provide attractive techanical and economical solutions to problems involving seismic, shock and vibration isolation. In this paper, it showed the noise and vibration characteristic was compared conventional rail joint to improved rail joint(damping alloy) for reducing noise and vibration. Its applicability to rail joint is discussed.

• 한국소음진동공학회논문집
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• 제13권1호
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• pp.56-62
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• 2003

The major noise source for the conventional train is the rolling noise caused by the interaction of the wheels and rails during the train passage on the tangent track. In order to control the rolling noise, the noise radiated from wheels, rails and sleepers should be analyzed and predicted. In this paper, a prediction method of wheel/rail rolling noise generated by the roughness of the wheel/rail surface is described, where the method is considering the effect of noise radiated by sleepers and the effect of ground. The method is applied to the Korean railway system, and the sound pressure level (SPL) predicted by the proposed method is compared with the measured SPL. Overall. the result shows good agreement between the predicted and measured values.

• 한국철도학회논문집
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• 제10권1호
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• pp.22-28
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• 2007

During the passage of the train, the railway bridge undergoes vibration and noise. The noise of railway bridge can be occurred from various sources. The wheel-rail contact, noise from machinery parts, structural-borne noise, pantagraph noise and aerodynamic noise of the train work in combination. Running train is one of the most important factors for railway bridge vibration. The repeated forces with equidistant axles cause the magnification of dynamic responses which relates with maintenance of the track structure and structure-borne noises. The noise problem is one of the most important issues in services of light rail transit system which usually passes through towns. In the present study, The vibration and noise of the LRT bridge will be investigated with utilizing dynamics responses from moving train as input data for noise analysis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.617-625
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• 2012

Non-contact detection of internal defects in a rail using ultrasonic waves is discussed in this paper. Cracks in a rail may be a cause of a serious railway accident such as derailment if left undetected. Concurrent rail inspection method based on ultrasonic testing using piezoelectric transducers has several limitations as it should keep physical contact with the rail. This work suggests a non-contact detection of internal defects in a rail using ElectroMagnetic Acoustic Transducers (EMAT) which can produce and measure ultrasonic waves in a rail without any couplant. The EMATs for rail inspection are designed and fabricated and their working performance is verified through a series of experiments on various types of internal defects in test rails. The effect of lift-off between the transducers and the rail on the generated signals is also discussed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.405-410
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• 2004

There are two types of noises in running the rail vehicle. The one is periodic by electric motors, dehumidifiers, and dusting machines. And the other is aperiodic squeal noise by the frictions between the wheels and the rail or the disks and pads. The periodic noises in rail vehicle have been reduced by changing DC motors to AC motors with silencers, and by improving the lubricants. However, almost nothing relating a periodic noise has been studied. In this paper, the experimental methods were applied to understand phenomena of the squeal noise, which was occurred by the friction variation due to aperiodic stick and slip with low repeatability in the process of dry friction of the disk and the pad when a rail vehicle was being braked. By the experimental acoustic test, it was found the specific frequencies relating the squeal noise. And by modal testing, it was measured the resonant frequencies in the disk and the pad-plate which were the components of the braking system, and in the whole braking system, and it was found the specific frequencies having the effects on the squeal noise.