• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.636-642
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• 2000

A method for reducing the contact noise of the Progressive Multi-Leaf Spring was investigated. It was found that the contact noise between the main and the help springs is the main source of the noise through our experiments. The conclusions from our experiments were compared with those from our numerical analysis by use of ABAQUS. The main parameters for the unexpected noise in the leaf spring were investigated through structural analysis to make describing noise generation. The contact process between the two leaves is examined by numerical calculations by ABAQUS. The noise produced by the leaf spring could be dramatically reduced by changing the shape of help spring so as to remove a translational jump of the contact point between the main and the help springs. Even with the help spring of the new proposed shape the stiffness of the whole spring did not change much.

• 대한의용생체공학회:의공학회지
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• 제39권2호
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• pp.103-108
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• 2018

This study reviews the common-mode noise model of indirect-contact ECG measurement which uses capacitive electrode and capacitive ground, and shows the reason of the large common-mode noise in indirect-contact ECG. And then, this study shows driven-right-leg ground in indirect-contact ECG measurement, and reviews how the driven-right-leg ground reduces the common-mode noise. This study then analyzes the relation between the effective area of the indirect-contact ground and the gain of the driven-right-leg circuit. This study introduces the output voltage saturation of the driven-right-leg circuit, which occurs frequently in indirect-contact ECG measurement with the condition of the high ground impedance. This study then shows the effect of the driven-right-leg circuit saturation on the common-mode noise.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.863-868
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• 2008

This paper investigates the abnormal noise of polygon mirror scanner motor due to the mechanical contact. In the high speed polygon mirror scanner motor the vibration of polygon mirror scanner motor is one of the main sources of abnormal noise, because structure-borne noise due to the vibration is bigger than aerodynamic noise, especially when the rotating part contacts the stationary parts. This research determines the main harmonics of structure-borne noise by using sound quality evaluation. It also develops an experimental set-up to measure the mechanical contact and vibration of polygon mirror scanner motor simultaneously. This paper also show that mechanical contact between rotating shaft and stationary sleeve is one of the dominant vibration sources of structure-borne noise which cause the abnormal noise of the high speed polygon mirror scanner motor by using the developed experimental set-up.

• 융합신호처리학회논문지
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• 제13권1호
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• pp.44-49
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• 2012

간접접촉 심전도 측정(Indirect-Contact ECG)은 일상생활에서의 무구속 무자각 측정에 적합한 새로운 심전도 측정 방법이다. 간접접촉 심전도 측정 에 서 관측되는 큰 배경 잡음을 줄이기 위한 기초 연구로서, 본 연구에서는 간접 접촉 심전도에서 사용되는 용량성 결합 능동 전극(Capacitively coupled active electrode)의 열잡음(Thermal Noise) 모델을 구성하였다. 실험을 통해, 용량성 결합 능동 전극만의 배경 잡음의 크기가 열잡음 모델에서 예상한 수준과 거의 일치함을 확인하였다. 면으로 된 직물의 실제의 전기적 특성을 열잡음 모델에 적용하여, 면 위에서 측정된 간접접촉 심전도의 이론적 열잡음을 계산하였다. 이 연구를 통해, op-amp의 내부 잡음(intrinsic noise)은 저항에 의한 열잡음에 비해 무시할 수 있을 정도로 작음을 알 수 있었다. 그리고 열잡음의 크기와 능동 전극의 입력 저항간의 관계를 도출할 수 있게 되어, 능동 전극의 입력 저항의 최적 값 선정을 위한 향후 연구의 기반이 되었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계 학술대회논문집(수송기계편)
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• pp.148-151
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• 2005

Roughness of a road is an important parameter which not only indicates vehicle's vibration and noise, but it is also related to the contact force of the tire which is induced by tire's deformation and vibration. Since tire noise indeed comes from this deformation and vibration, the estimation of the force is the key factor fur the reduction of tire noise. Because of the difficulty of directly measuring the contact force, the indirect estimation is enforced from the vibration signature measured on the tire support. This study suggests the "inverse filtering" technique well known in modern digital signal processing, so as to reform the tire contact force from monitored vibration signals.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.607-612
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• 2004

Disc brake noise continues to be a major concern throughout the automotive industry despite efforts to reduce its occurrence. Eliminating vibrations during braking is an important task for both vehicle passenger comfort and reducing the overall environmental noise levels. There are several classes of disc brake noise, the major ones being squeal, judder, groan, and moan. In this study, analytical model for moan noise of rear disk brake is investigated. Modeling of the disc brake assembly to take account of the effect of different geometrical and contact parameters is studied through the use of multi-body model. The contact stiffness of the caliper and torque member plays an important role in controlling brake vibration. Therefore, a suitable material pair at the caliper/body contact has been made. An ADAMS model of a rear disc brake system was integrated with a flexible suspension trailng arm from MSC/NASTRAN. A fully non-linear dynamic simulatin of brake system behavior, containing rigid and flexible bodies, was performed for a Prescribed set of operating conditions. Simulation results were validated using data from vehicle experimental testing.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.281-285
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• 2002

A new method of dynamic contact force measurement between a pantograph and a contact wire is proposed in this paper The method does not require design modification of an original pantograph in order to install sensors such as load cells. Contact forces can be expressed as the sum of vertical shear forces at the support points and inertial forces. Using specially-designed strain gage rosettes. vertical shear forces at the supported points can be measured without noise mixing and thermal effects. In order to obtain contact forces from shear forces, 3 inertial force compansation methods are proposed and compared in this paper. By validation process, the new proposed measurement method is verified to be applicable to the on-line current collection test.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1120-1124
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• 2007

Recently in the automotive brake industry brake squeal noise has become one of the top automotive quality warranty issues. The contact pressure is used to predict friction coupling in the brake squeal analysis. The formulation of friction coupling has performed by nonlinear static analysis prior to the complex eigenvalue analysis. This paper proposes a validation methodology of squeal analysis using modal testing and contact analysis and examines the effect of predicted contact pressure that leads to the discrepancy between unstable complex mode and squeal frequency. This studies compose a three step validation process : examining the modal characteristics of component and assembly loaded contact pressure using modal testing and FEM analysis and verifying the contact pressure distribution using nonlinear static analysis and experiment. Finally, the unstable modes from complex eigenvalue analysis and realistic squeal frequency from the noise dynamometer are investigated.

• 소음진동
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• 제10권3호
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• pp.444-450
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• 2000

Wheel-rail noise is normally classified into three catagories : rolling impact and squeal noise. In this paper rolling noise caused by the irregularity between a wheel and a rail is analysed as follows: The irregularity between the wheel and the rail is assumed as linear superposition of sinusoidal profiles. Wheel-rail contact stiffness is linearized by using Hertzian contact theory and then contact force between the wheel and the rail is calculated. vibration of the rail and the wheel is calculated theoretically by receptance method or FEM depending on the geometry of the wheel or the rail for the frequency range of 100-500 Hz important for noise generation. The radiation noise caused by those vibration response is computed by BEM To verify this analysis tools rolling noise is calculated by proposed analysis steps using typical roughness data and these results are compared with experimental rolling noise data. This analysis tools show reasonable results and finally used for the prediction of the Korean high speed train rolling noise.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.555-564
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• 2001

Wheel-rail noise is normally classified into three catagories ： rolling, squeal and impact noise. In this paper, rolling noise caused by the irregularity between a wheel and rail is analysed as follows： The irregularity between the wheel and rail is assumed as combination of sinusoidal profiles. Wheel-rail contact stiffness is linearized by using Hertzian contact theory, and then contact force between the wheel and rail is calculated. Vibration of the rail and wheel is calculated theoretically by receptance method or FEM depending on the geometry of wheel or rail for the frequency range of 100-5000Hz, important for noise generation. The radiation caused by those vibration is computed by BEM. To verify this analysis tools, rolling noise is calculated by preceding analysis steps using typical roughness data and it is compared with experimental rolling noise data. This analysis tools show reasonable results and used for the prediction of KTX rolling noise.