• 한국음향학회지
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• 제30권4호
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• pp.223-230
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• 2011

한국종은 지면으로부터 일정한 간극을 두고 매달리며, 종 아래에 명동이라고 불리는 독특한 음향학적 요소를 갖고 있다. 간극과 명동의 적절한 설계는 공명효과에 의하여 종소리를 극적으로 증폭시킨다. 종체의 내부공동과 간극, 그리고 명동으로 구성된 음향공동계는 공명주파수와 모드를 갖는데, 공명주파수가 종체의 고유진동수에 일치하게 되면, 그 주파수성분이 크게 증폭된다. 이 연구는 성덕대왕신종을 대상으로 간극효과를 고려한 명동의 공명조건을 처음으로 제시한다. 공명조건을 구하기 위하여 신종의 실제 치수를 사용하여 SYSNOISE를 이용한 경계요소해석을 수행하였다. 또한, 계절에 따른 기온의 차이가 공명조건에 어떠한 영향을 미치는가를 규명하고, 가변형 명동의 개념을 제시함으로써, 현장에서 온도차를 보정하여 정확한 공명조건을 구현시킬 수 있는 방안을 제공한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.596-599
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• 2008

Traditionally, tire made a role of function, which is supporting vehicle load, making brake, transferring traction, etc. But tire is a part of vehicle design, nowadays. In accordance with this market trend, customers need a wide tread design tire (i.e. low series tire). Generally low Series Tire means stiffer than general tire. That brings out increasing road noise. (Especially tire cavity resonance noise) Tire noise is divided in structure home noise and air borne noise. Tire cavity resonance noise (structure home noise) come from vibration between tire and vehicle. In the study, we investigated that tire cavity resonance noise is affected by stiffness of tread and sidewall.

• 설비공학논문집
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• 제12권3호
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• pp.302-308
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• 2000

The major source of noise in air-conditioner is a compressor. Therefore, noise reduction in a compressor is quite significant as an element technology in air-conditioner field. Recently, a scroll compressor is widely used, because a scroll compressor features lower noise, due to less pulsation of gas pressure, than that of the rotary compressor. During a past noise reduction effort on a scroll compressor, noise radiation from the discharge portion of the hermetic shell was identified as the major contributor to overall noise. For a reduction of noise, the source of noise at the discharge portion must be identified. This paper presents detailed analyzes for the discharge pressure pulsation and cavity resonance at discharge space, which will make possible a low noise design of a scroll compressor.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계 학술대회논문집(수송기계편)
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• pp.129-133
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• 2005

Vibration transmitted through rolling tire is a major source of road noise in vehicle interior noise on the range of low frequency.($0{\sim}500Hz$) Among various road noises, tire cavity noise has very peak on $200{\sim}250Hz$. And generally it is generated by cavity resonance of tire. In this paper, tire cut-sample is used to calculate the tire cavity frequency. Cavity resonance frequency of tire is measured through vertical/tangential forces at load cell of axle using drum cleat impact. This method is useful to find cavity peak because measured forces do not have complex peaks. And changing the test conditions (air inflation, loads), tire cavity resonance characteristics are identified. Finally, vehicle interior noise is measured as tire/vehicle are changing. As difference of tire vertical force is bigger, interior noise level is higher at cavity frequency. Also we can assume that vehicle sensitivity is important factor at tire cavity noise.

• International Journal of Automotive Technology
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• 제5권3호
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• pp.209-213
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• 2004

The objective of this paper is to introduce the noise reduction characteristics of a double gap system, which is composed of two air-gaps and two partition sheets. The resonance of acoustic modes of an enclosed cavity can be effectively suppressed by installing the double gap system in the cavity. It is revealed from a simple, one-dimensional model that the double gap system is more effective than the single gap system that consists of one air-gap and one partition sheet, in that the former requires a smaller space than the latter. Finally, these theoretical conclusions are verified by comparison experiments using an actually manufactured enclosed cavity, of which the boundary surfaces are made of thick panels that can be assumed as rigid walls.

• 한국자동차공학회논문집
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• 제15권6호
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• pp.44-49
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• 2007

It is well known that the acoustic cavity inside the tire-wheel assembly contributes to vehicle interior noise. In this paper, we have performed acoustic and structural modal testings to investigate the influences of the acoustic cavity resonance on structural vibration characteristics for the tire in free-suspension and for the loaded tire. The testings have given us some findings, which are reported in this paper.

• 한국자동차공학회논문집
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• 제16권3호
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• pp.102-110
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• 2008

It is well known that the acoustic cavity inside the tire-wheel assembly contributes to vehicle interior noise and ride comfort. In this paper, we performed acoustic and structural modal testings by varying the temperature ranging from $20^{\circ}\;to\;45^{\circ}C$ to investigate the effects of temperature on acoustic cavity resonance and structural vibration characteristics for unloaded and loaded tires. The testing has given us some findings, which are reported in this paper.

• 한국소음진동공학회논문집
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• 제19권7호
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• pp.685-692
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• 2009

Vehicle interior noise is the results of numerous sources of excitation. One source involving tire pavement interaction is the tire cavity resonance and the forcing it provides to the vehicle spindle. Using a simplified model for the tire acoustic cavity system only, we formulated finite element equation to predict the fundamental acoustic cavity resonant characteristics inside tire-wheel assembly of undeformed and deformed tire. Combining the finite element analysis with experimental verification, we explained the acoustic characteristics theoretically. Especially, we have shown that the difference between the first two resonant frequencies increases as the deformation of deformed tire increases.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.551-556
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• 2009

Vehicle interior noise is the results of numerous sources of excitation. One source involving tire pavement interaction is the tire cavity resonance and the forcing it provides to the vehicle spindle. Using a simplified model for the tire acoustic cavity system only, we formulated finite element equation to predict the fundamental acoustic cavity resonant characteristics inside tire-wheel assembly of undeformed and deformed tire. Combining the finite element analysis with experimental verification, we explained the acoustic characteristics theoretically. Especially, we have shown that the difference between the first two resonant frequencies increases as the deformation of tire due to vertical load increases.

• 한국의학물리학회지:의학물리
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• 제33권4호
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• pp.142-149
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• 2022

Purpose: This study seeks to compare the dosimetric parameters of the bulk electron density (ED) approach and synthetic computed tomography (CT) image in terms of position variation of the air cavity in magnetic resonance-guided radiotherapy (MRgRT) for patients with pancreatic cancer. Methods: This study included nine patients that previously received MRgRT and their simulation CT and magnetic resonance (MR) images were collected. Air cavities were manually delineated on simulation CT and MR images in the treatment planning system for each patient. The synthetic CT images were generated using the deep learning model trained in a prior study. Two more plans with identical beam parameters were recalculated with ED maps that were either manually overridden by the cavities or derived from the synthetic CT. Dose calculation accuracy was explored in terms of dose-volume histogram parameters and gamma analysis. Results: The D_95% averages were 48.80 Gy, 48.50 Gy, and 48.23 Gy for the original, manually assigned, and synthetic CT-based dose distributions, respectively. The greatest deviation was observed for one patient, whose D_95% to synthetic CT was 1.84 Gy higher than the original plan. Conclusions: The variation of the air cavity position in the gastrointestinal area affects the treatment dose calculation. Synthetic CT-based ED modification would be a significant option for shortening the time-consuming process and improving MRgRT treatment accuracy.