• 한국소음진동공학회논문집
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• 제16권12호
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• pp.1244-1251
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• 2006

The objective of this paper is to get excitation forces of the engine at each of the brackets for the prediction of the vehicle interior noise by the powertrain. A powertrain geometry model is produced by CATIA and its FE model is made by MSC/Patran. A vibration mode analysis and a running mode analysis are experimentally implemented. After getting a satisfied MAC value by doing a correlation about a measured mode analysis value and analyzed value through MSC/Nastran software, all components are assembled through MSC/ADAMS software which is a dynamic analysis tool. We can predict the vibration of brackets which is the last points to occur the force of the engine combustion by analyzing the combustion force produced by engine mechanism.

• 한국소음진동공학회논문집
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• 제23권12호
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• pp.1073-1081
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• 2013

The definition of the radiation efficiency is very important to estimated underwater radiated noise of a ship. Considering the structure of the ship, it can be found that the hull of a ship consists of a lot of plates supporting by longitudinal and transverse stiffener. Therefore, various modes of the hull vibration occur related to the combination of these plates including stiffeners. In this paper, the method to define the radiation efficiency is suggested considering the vibration mode of the hull based on Uchida's experimental equation of the radiation efficiency. The suggested method is verified by the experiments with various kinds of naval vessels.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1648-1653
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• 2000

Theoretical analysis of noise reduction by a membrane-duct system is presented. When acoustic waves propagate in the membrane-duct, the part of membrane is also excited and its motion is coupled with interior medium. For an infinite plane membrane-duct system, a simple coupled governing equation is derived and solved. One of the characteristics of dispersion relation is that evanescent waves occur below critical frequency. Attaching damping materials to the membrane may improve the absorption efficiency of acoustic energy. The results show that the membrane-duct system can be applied to diminish and absorb low frequency noise in duct instead of passive muffler, such as simple expansion chamber or absorption material.

• 한국정밀공학회지
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• 제12권12호
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• pp.109-119
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• 1995

A driveline incorporating universal joints when driving through an angle can excite various components in a vehicle with second order excitation of torsional and bending vibrations, being transmitted either audibly(noise), or physically(vibration). For a certain range of vehicle dpeed noises can be radiated from the cab wall, in which resonances occur by the excitations transmitted from the driveline as a vibration source. In this paper, the excitation mechanism of cab noises is studied especially for the vehicle speed range of 65 .approx. 75 km/h through the simulation for torsional vibrations of the driveline and for bending vibrations of the cab of an 11 Ton grade Cargo Truck, and verified additionally by vibration and noise measurements. As a result, it is found that the uncomfortable noises in the cab are caused mainly by the abrupt increase of the joint angle of driveline near the axle differential resulted from the excessive clearance alignment of the leaf spring gate.

• 한국컴퓨터산업학회논문지
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• 제8권2호
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• pp.81-88
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• 2007

본 논문은 통신중 발생 할 수 있는 잡음(Noise)이 영상정보에 주는 영향을 확인하고 그것을 가능한 한 원본영상정보에 가깝게 잡음을 제거 할 수 있는 Nagao필터를 분석하고 기존의 Nagao필터보다 더 나은 성능을 위하여 다른 분할영역을 설정하여 MSE(Mean Square Error)를 줄일 수 있는 필터를 제안하고 모의실험과 그 결과를 통하여 이 방법의 우수성을 확인한다.

• 대한전자공학회논문지SD
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• 제41권2호
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• pp.77-83
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• 2004

on-chip 상에서 발생하는 누화 잡음은 신호의 충실성을 위협하는 매우 중요한 요소이다. 따라서 본 논문에서는 최대 누화잡음의 크기를 예측하는 해석적인 방법을 제안한다. 정확한 잡음 수치를 예측하기 위해 연결선의 인덕턴스 성분을 고려하였고, 임의의 램프입력을 사용하였다. 또한 복잡한 누화 잡음 모형에서 최대 누화 잡음을 해석적으로 간단히 구하기 위해 가상의 소스 개념을 도입하였다. 된 연구에서 제안한 방법은 HSPICE 시뮬레이션 결과와 비교하여 최대 상대오차 4.3％ 이내의 정확도를 보였다. 따라서 본 연구는 신호 충실성 보장을 위한 다양한 설계 보조 도구 개발에 활용될 수 있을 것으로 본다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.413-418
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• 2000

The noise sources from a rotating cylinder were identified to describe the blunt trailing edge noise. Firstly, LES formulation was applied to a non-orthogonal grid system and was tested with three-dimensional cross-flow over a cylinder with a yaw angle. The computed far-field noise showed peaks at Strouhal numbers ranging from 0.135 to 0.165 for the yawed cylinder flow with end-plates placed at both extremes under the yaw angle of $30^{\circ}$ and Reynolds number of $1.15{\times}10^4$. It was observed that the slantwise shedding at angles other than the cylinder yaw angle is intrinsic to inclined cylinder, with the result of shedding angles between $15^{\circ}$ and $31^{\circ}$. To study the trailing-edge wake thickness and unsteady lift-coefficient distribution in the span-wise direction of a rotating fan blade, the flows around rotating cylinder with 1,000 rpm were simulated and the far-field noise was exactly computed using the Ffowcs-Williams and Hawkings equation with quadrupole source term. The incoming velocities and stagnant zones were continuously distributed along the cylinder, and their changes made the Strouhal sheddings to occur at different phases even at almost same Strouhal number.

• 소음진동
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• 제13권2호
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• pp.109-118
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• 2003

With the rising utilisation of electrical machines to increase the output-Power of the device several problems occur. Next to probable additional losses and other parasitic effects, aspects concerning the audible noise radiated by the device are of particular interest. This contribution is intended to give an overview to the problematic of the analysis of vibrations and audible noise radiated by electrical machines. It is not the intention of the authors to set off a scientific firework with various complicated equations in this contribution. The paper should rather give an insight in a complicated technical matter and should help to understand the mechanism of vibration and parasitic noise generation in electrical machines. Rotating machines, such as the induction motor as well as non-rotating electrical machines, such as inductors or transformers are studied. The origin of vibrations leading to noise radiations is studied and discussed to illustrate the way in which the analysis of the governing effects can be performed. Magnetically generated radial pullout force waves in rotating electrical machines are the main cause of the excited audible noise, whereas magnetostriction plays an important role in transformers.

• Journal of the Korean Data and Information Science Society
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• 제11권2호
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• pp.157-172
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• 2000

Metal containers represent a situation where a specific metal is exposed to a wide variety of electrolytes of varying degrees of corrosivity. For example, hundreds, if not thousands of different products are packaged in an aluminum beverage can. These products vary in pH, chloride concentration and other natural or artificial ingredients which can effect the type and severity of potential corrosion. Both localized (perforation) and uniform corrosion (metal dissolution without the onset of pitting) may occur in the can. A quick test or series of tests which could predict the propensity towards both types of corrosion would be useful to the manufacturer. Electrochemical noise data is used to detect the onset and continuation of pitting corrosion. Specific noise parameters such as the noise resistance (the potential noise divided by the current noise) have been used to both detect pitting corrosion and also to estimate the pitting severity. The utility of noise resistance and other electrochemical parameters has been explored through the application of artificial neural networks. The versatility of artificial neural networks is further demonstrated by combing electrochemical data with electrolyte properties such as pH and chloride concentration to predict both the severity of both localized and uniform corrosion.

• 디지털융복합연구
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• 제11권7호
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• pp.135-140
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• 2013

잡음 추정과 검출 알고리즘에서는 LMS Filter를 이용하여 변화하는 잡음 환경에 빠르게 적응할 수 있도록 한다. 하지만 LMS Filter는 잡음 추정을 위한 일정 시간 동안 적응 시간이 필요하며 신호의 변화가 일어날 경우 더 많은 적응 시간이 소요되는 단점을 가지고 있다. 따라서 이를 보완하기 위하여 프레임 단위의 AELMS Filter를 이용한 잡음 제거 방법을 제안한다. 본 논문은 잡음 환경에서 입력되는 신호를 프레임 단위로 분할하고 평균과 분산을 이용한 예측 LMS Filter를 구성하여 잡음을 제거하므로 잡음 환경이 변화하더라도 빠른 적응 시간으로 잡음을 제거한다. 또한 환경 잡음과 음성 신호가 혼합되어 입력될 때 잡음을 제거하여 음성의 고유 특성을 유지하고 음성 정보 손상을 줄이기 위한 방법이다. 프레임 단위의 AELMS Filter를 이용한 잡음 제거 방법으로 잡음 제거 성능을 평가하였다. 실험 결과 변화하는 환경 잡음을 제거하여 얻은 감쇠도가 평균 6.8dB 향상되었다.