• 한국자동차공학회논문집
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• 제12권5호
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• pp.118-124
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• 2004

To investigate the mechanics of brake squeal noise, the sound and vibration of an actual brake system was measured using a brake dynamometer. The experimental results show that disk run-out due to the misalignment of brake disk varies with brake line pressure and becomes the important factor of brake squeal noise generation. Also, it was confirmed that the frequency of the squeal noise equals to the natural frequency of the disk bending mode.

• 한국소음진동공학회논문집
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• 제21권1호
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• pp.41-46
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• 2011

In this paper, we experimentally investigate factors that decrease in noise of a industrial take-out robot at driving state. For this, we analyse change in the noise of the take-out robot with gear machining accuracy and clearance. In order to calculate the noise related to gear machining accuracy that is based upon the Japanese Industrial Standard(JIS), we equally increase motor speed from 0 rpm to 1250 rpm. In addition, to investigate influence of clearance on noise, we evenly change clearance from 0.5 mm to 1.2 mm. These experiments show that clearance is more effective factor than gear machining accuracy to reduce the noise of the take-out robot.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.675-679
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• 2006

Today, the interior noise perceived by the occupants is an important factor in the design of automotive interior assemblies. Buzz, Squeak and Rattle Noises in a Seats are one of the major concerns mentioned above. In this study, the terms 'Buzz, squeak and rattle' were defined as the noise originating from structural vibrations in an assembly. And, the BSR noise of vehicle seat was investigated and the improvement of BSR noise level was confirmed though the structural treatment based on the structural analysis results from the modal and sound intensity of seat.

• 한국소음진동공학회논문집
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• 제15권6호
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• pp.718-723
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• 2005

The purpose of this study is to present a fundamental data for evaluating aircraft noise of building site development. By the field experiments and the predicted equal noise level contours using the INM program, actual condition in the building site development arranged district was investigated. In order to get the results, Analysis of factors effected on noise level, sound level on the rate of increase to aircraft demand and difference on the aircraft noise levels according to floor level in apartment house was carried out. As a result the influence of the take-off and landing direction were appeared greatly. The influences of the height at receiving point, movement number of aircraft and increase to aircraft demand were appeared small And the influence of 1 day average WECPNL must be considered.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.796-799
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• 2014

It is treated more seriously than ever as the customer requirements are becoming a high-quality and diversification. Among the various elements to affect customer's evaluation of automobile quality, BSR(buzz, squeak, rattle noise) are considered to be a mostly contributing factor. Rattle Noises in cockpit modules are one of the major concerns mentioned above. Recently, measurements of the BSR noise between the parts that make up the products from the perspective that the structural causes. For structures that make up material has not been any consideration of the BSR noise characteristics. The aim of this study is to clarify the characteristics of noise occurrence in vehicle cockpit module that consist of plastic material after measuring noise by rattle special testing instrument.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.447-453
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• 2012

Nowadays, high speed train has settled down as a fast and convenient environment-friendly transportation and it's need is gradually increasing. However increased train speed leads to increased aerodynamic noise, which causes critically affects comfortability of passengers. Especially, the pantograph of high speed train is protruded out of train body, which is the main factor for increased aerodynamic noise. In this research, to reduce aerodynamic noise pantograph, panhead's shape changed to aerodynamical shape. aerodynamic noise of pantograph is predicted by CFD (Computational Fluid Dynamic) and FW-H (Ffowcs Williams-Hawkings) equation. Also, the sound pressure level of aerodynamic noise of base and modified models are predicted. And the reduction effects of the sound pressure level is analyzed.

• 한국소음진동공학회논문집
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• 제16권5호
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• pp.503-513
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• 2006

The duration time of aircraft noise event is also an important factor for the evaluation of civil aircraft noise, which is considered as a notable characteristic of military aircraft noise. SEL is proved as a suitable noise metric for the measuring military aircraft noise of various flight pattern considering the duration time of noise event. This study reviews whether SEL is a suitable for measuring civil aircraft noise and study shows SEL is fairly compensating the duration time of civil aircraft noise event for the evaluation of aircraft noise. Noise metric for the evaluation aircraft noise based on SEL is more appropriate than based on $L_{MAX}$ for compensating duration time of noise event either military aircraft or civil aircraft. In this reason, current formula of WECPNL based on energy average of measured $L_{MAX}$ for the evaluation of aircraft noise impact in 'Test Method of Noise and Vibration of Korea' is recommended to be amended to formula of WECPNL based on energy average of measured SEL considering compensation of noise event duration time, if WECPNL is not based on measured EPNL, a metric compensating duration time.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.528-532
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• 2013

본 연구에서는, 해석적 모델로 불규칙하게 분포된 질량을 가진 열탄성 댐핑을 포함하는 마이크로빔 구조물을 연구하였다. 마이크로 스케일의 기계적 공명체(mechanical resonator)에 대한 열탄성 댐핑의 중요성은 높은 Q-factor를 설계하는데 고려된다. 본 연구에서의 빔 모델은 Euler-Bernoulli 빔 이론을 기조로 한다. 빔의 고유 진동수를 결정하기 위하여, 에너지 기법이 적용되었다. 또한, 열탄성 댐핑 효과는 열전도 방정식을 사용할으로써 고려되었고, Q-factor가 결정될 수 있었다. 운동방정식의 유도에는 체계적인 무차원화를 수행하였다. 임의의 집중된 질량을 포함하는 열탄성 댐핑을 가진 마이크로빔에 대해 모델의 결과값을 입증하였고 mode shape과 Q-factor를 제시하였다.

• 한국환경과학회지
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• 제16권7호
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• pp.823-830
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• 2007

Traffic noise is a kind of noise caused by cars, trains and aircraft. Among them, noise produced by cars is the most important factor in cities. According to the National Institute of Environmental Research(NIER)'s survey, Road traffic noise levels in Susan are the highest of all the cities in Korea. So, appropriate measures for road traffic noise reduction is required. For this purpose, the construction of a noise map in Susan will playa vital role. However, road traffic noise formulas are constructed considering regional characteristics such as each country road's environment and vehicle quality. Therefore, prior to constructing a noise map in Susan, examination processes about each formula constituent status and estimation process are required preferentially. In this research, the basic first stage is to estimate Susan's road traffic noise. First, investigate characteristics of each road traffic noise estimate and using this, a noise map is constructed for road traffic noise in Susan. Then the adaptation of a road traffic noise formula is evaluated.

• 한국통신학회논문지
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• 제11권6호
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• pp.411-420
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• 1986

本 論文에서는 델타變調(Delta Modualation:DM) 符號器의 入力에 音聲帶域信號를 使用하였을 때 非適應形인 線形變調方式(Linear Delta) Modulation:DOM)과 適應形인 一定係數變調方式(Constant Factor Delta Modulation:CFDM)을 比較하였다. 샘플링레이트(sampling rate)를 16~96kb/s로 變化시키면서 測定, 比較한 結果 20kb/s에서는 適應形이 非適應形보다 信號對量子化雜音比(Signal-to-Quantization Noise Ratio:SQNR)가 8〔dB〕改善되었고 60kb/s에서는 平均 14〔dB〕정도 改善되었다. 특히 雜音이 없는 理想的 채널에서는 最大 SQNR이 거의 비슷하고 CFDM이 LDM보다 넓은 다이나믹범위(Dynamic range)를 가지나 雜音이 있는 채널에서는 CFDM의 誤差率이 증가하여 SQNR이 떨어진다는 것을 알 수 있었다.