• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 추계학술대회논문집 II
• /
• pp.1273-1279
• /
• 2001

Precise highway traffic noise simulation and reduction require the accurate data for sound power levels emitted by vehicles, varied to road surface, traffic speed, vehicle types and makers, different from countries to countries. In this study, we have elaboratively measured domestic highway traffic noise and parameters affecting noise levels at the nearside carriageway edge. From numerical simulation using the measured results for highway traffic noise, we propose not only two correction factors to enhance the accuracy of highway traffic sound power estimation using ASJ Model-1998 but also its typical power spectrum according to road surface type. The measured and predicted highway traffic noise levels using the proposed sound power shows little difference within 1 dB.

• 한국소음진동공학회논문집
• /
• 제16권8호
• /
• pp.806-813
• /
• 2006

An important factor of vibration test using MAST(multi axial simulation table) system is the reliance of input excitation source. Generally the generation of input excitation source is obtained by the measured data on special road in proving ground. The measured data on special road have more exciting energy than the data of real fields, therefore the time and expense for test can be reduced. But the magnitude of input excitation source must be defined by comparison with the excited energy on real field. The object of this paper makes the data base of domestic roads for the definition of input excitation source which is obtained by the measured data on special road in proving ground. These real field data on domestic roads are analyzed by the power spectral density and interrelationship index.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2005년도 추계학술대회논문집
• /
• pp.79-83
• /
• 2005

SEA is a useful tool to predict noise and vibration response in high frequency region but has a weak point not to be able to express modal behavior in low frequency region. For a structure with middle subsystem having relatively higher modal density than excited subsystem and receiving subsystem, we studied the possibility that the modal behavior of receiving subsystem can express by considering finite mobility of excited subsystem. For a simply three-coupled beams which is chosen for feasibility study, the response of receiving beam was investigated with varying the length & area moment of inertia of middle beam. In case that the middle beam has relatively higher modal density than exciting beam, the application to finite mobility of excited beam led to express modal behavior of receiving beam relatively well.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2004년도 추계학술대회논문집
• /
• pp.949-953
• /
• 2004

In this paper, Power Flow Boundary Element Method(PFBEM) is studied as the numerical method for the vibration and sound predictions of complex structures in medium-to-high frequency ranges. NASPFA, the sound analysis software based on PFBEM, is developed and is used for the vibro-acoustic analysis. And also the developed software is used for the prediction of interior and exterior sound fields of vibrating structures and for the analysis of the multi-domain problems. To verify the accuracy, NASPFA is applied to the prediction of the energy distribution in the simple structures, and its results are compared with exact PFA solutions. And various practical vehicle systems are modeled and the distributions of the acoustical energy density are successfully predicted.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2004년도 추계학술대회논문집
• /
• pp.782-785
• /
• 2004

In the Well-being age, many people use a city park for rest deeply think and constitutional walk. The city park is located at near side by traffic road in urban. Citizens are not satisfied with it's fuction as a haven of peace due to road traffic noise. Thus, this study is for a research on the actual noise condition of a city park in Nowon go. This study uses a prediction method called ASJ-model in order to calculate PWLs of road traffic noise. Using calculated PWLs, noise levels in a park are predicted and compared with measured values.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2004년도 추계학술대회논문집
• /
• pp.554-558
• /
• 2004

In this paper, we introduce noise prediction program of HVAC system to assist low-noisy design of ship's cabin. The developed program calculates sound power levels at HVAC components considering primary and secondary noise generated by fan and duct element, duct element noise attenuation, and duct break-in noise based on the authentic empirical method suggested by NEBB and acoustic power balancing method. Sound pressure level at cabin with or without ceiling system is evaluated by the diffuse-field theory considering diffuser and duct break-out sound powers. Moreover, the program provides intuitive pre- and post-processors using modem GUI functions to help efficient modeling and evaluation of cabin and HVAC component noise. To validate the accuracy and convenience of the program, noise prediction for a HVAC system is demonstrated.

• 한국음향학회지
• /
• 제35권3호
• /
• pp.183-191
• /
• 2016

자동차의 저소음 보기류 구동 시스템을 개발하는 체계적인 방법론이 전산해석과 리그 실험을 통해 제시되었다. 벨트 구동 소음 예측의 두 가지 난제는 1) 벨트와 풀리 접촉면에서의 스틱-슬립 비선형성과 2) 벨트 구동 시스템과 파워트레인 회전진동계와의 연성이다. 본 연구에서는 최근 개발된 해석 방법을 이용하여 벨트 구동시스템과 엔진 회전진동계를 통합한 해석 모델을 구축하였고, 다양한 파워트레인 운전 조건에서 정합성을 확보하였다. 통합 모델을 이용하여 스틱-슬립 소음이 발생하는 벨트 시스템을 개선할 수 있음을 확인하였다. 또한 새로운 방법론을 통해 신엔진 개념설계에서 NVH (Noise, Vibration and Harshness), 기능, 연비 등을 고려한 개념 설계안을 제시하였다.

• 한국소음진동공학회논문집
• /
• 제22권3호
• /
• pp.203-207
• /
• 2012

The noise emitted from an excavator has long been a cause of environmental disputes, while causing displeasure to the nearby residents. So, the ministry of environment adopted the construction machinery noise labeling system to encourage the construction machinery manufacturing companies to develop the low noise construction machinery voluntarily. But, as the quality of life improves, a growing number of people desire the comfortable and quite environment to live in. Under the situation, noise from the construction machinery has been a major cause for stress and complaints. When the noise dispute happened in the construction site, the sound pressure level of the construction machinery like a excavator was measured at the lot boundary of the noise victim's residence to judge how much noise damage occur. But the sound pressure level of the construction machinery is measured differently according to the acoustic environment of construction site and the measuring position, respectively, which makes it difficulty to judge whether the noise damage occur or not. As the sound power level of noise source is not affected by the acoustic environment of construction site and the measuring position, if we use the information of the sound power level, it will be easy to judge whether the noise damage occur and to establish the soundproofing measures. Therefore, we derive the sound power level regression model of the excavator to judge whether the noise emitted from the excavator damages to residents near the construction site. Also, the sound power level regression model of the excavator drawn in this paper will help construction companies to plan the noise reduction program in the construction sites.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2006년도 춘계학술대회논문집
• /
• pp.941-945
• /
• 2006

In the development of electricity generating wind turbines for wind farm application, only two types have survived as the methods of power regulation; stall regulation and fun span pitch control. The sound measurement procedures of IEC 61400-11 are applied to field test and evaluation of noise emission from each of 1.5 MW and 660 kW wind turbine generators (WTG) utilizing the stall regulation and the pitch control for the power regulation, respectively. Apparent sound power level, wind speed dependence and third-octave band levels are evaluated for both of WTGs. It is found that while 1.5 MW WTG using the stall control is found to emit lower sound power than 660 kW one using the pitch control at low wind speed (below 8 m/s), sound power from the former becomes greater than that of the latter in the higher wind speed. Equivalent continuous sound pressure levels (ECSPL) of the stall control type of WTG vary more widely with wind speed than those of the pitch control type of WTG These characteristics are believed to be strongly dependent on the basic difference of the airflow around the blade between the stall regulation and the pitch control types of WTG. These characteristics according to the methods of power regulation lead to the very different noise emission characteristics of WTG depending on the seasons because the average wind speed in summer is lower than the critical velocity over which the airflow on the suction side of blade in the stall types of WT are separated. These results propose that, in view of environmental noise regulation, the developer of wind farm should give enough considerations to the choice of power regulation of their WTG based on the weather conditions of potential wind farm locations.

• 대한기계학회논문집A
• /
• 제39권5호
• /
• pp.499-505
• /
• 2015

압전 진동 에너지 수확 장치의 설계 및 성능 평가 시 에너지 변환 효율을 고려하는 것은 매우 당연하다. 본 연구에서 고려하는 에너지 변환 효율은 부하 저항이 부착된 압전 진동 에너지 수확 장치에 입력되는 가진 진동 파워 대비 전기 출력 값으로 정의된다. 기존의 연구에서는 근사적으로 임피던스 정합된 부하 저항에서의 전기 출력을 고려한 반면, 본 연구에서는 최적의 임피던스 정합 값을 사용하여 새롭게 에너지 변환 효율 식을 유도하였다. 유도된 식의 타당성을 검증하기 위해 3 개의 서로 다른 전기-역학 연성 계수 값을 갖는 진동 에너지 수확 장치에 대한 유한 요소 해석 결과를 이용하였다. 또한, 부하 저항의 임피던스 정합 방법의 차이에 따른 에너지 변환 및 변환 효율 특성을 살펴보았다.