• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 1997년도 춘계학술대회논문집; 경주코오롱호텔; 22-23 May 1997
• /
• pp.557-563
• /
• 1997

In order to satisfy the regulations concerned with the noise emission of fork-lift trucks and thereby increase export to the western countries, a noise reduction technique should be developed in the early design stage. In this paper, several noise sources are identified using the sound suppression method and sound intensity measurement, and their contributions to the sound levels at the operator's ears and at the distance of 7m from the vehicle are studied. For each of the major noise producting components, noise abatement alternative are suggested and their effects are analyzed.

• 한국군사과학기술학회지
• /
• 제19권1호
• /
• pp.66-75
• /
• 2016

Stereoscopic image generated by depth image-based rendering(DIBR) for surveillance robot and camera is appropriate in a low bandwidth network. The image is very important data for the decision-making of a commander and thus its integrity has to be guaranteed. One of the methods used to detect manipulation is to check if the stereoscopic image is taken from the original camera. Sensor pattern noise(SPN) used widely for camera identification cannot be directly applied to a stereoscopic image due to the stereo warping in DIBR. To solve this problem, we find out a shifted object in the stereoscopic image and relocate the object to its orignal location in the center image. Then the similarity between SPNs extracted from the stereoscopic image and the original camera is measured only for the object area. Thus we can determine the source of the camera that was used.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2000년도 추계학술대회논문집
• /
• pp.125-131
• /
• 2000

The turbo chiller uses centrifugal compressor, which operates at about 14500 rpm. Due to the high rpm of the impeller, the noise of chiller makes one of the serious problems. The possibility of the sound reduction by using absorbing material is studied in this paper. The generated sound propagates through the duct and then radiates to the outer field. So, the use of sound absorption material inside the duct is one of the effective methods. To study the effect of location of the material, we use Boundary Element Method to analyze the sound field inside the duct system. Numerical study shows the highest sound pressure region is near the elbow of curved duct. From the analysis, it is also shown that the elbow duct is the main radiator of noise and sound absorption treatment of this duct results noise reduction of the highest noise level at BPF and high frequency region.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2006년도 추계학술대회논문집
• /
• pp.54-60
• /
• 2006

This study looks over the relation between propeller and noise in ship stern structure. Near field noise and vibration measurements are compared with the analytical results using wave number method. To avoid singularity in wave number integration method, fast field method is introduced. Analytical results show that main transmission mechanism of high frequency noise is structure-borne type and that of low frequency noise is a air-borne type.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 춘계학술대회논문집
• /
• pp.349-354
• /
• 2007

This paper considers acoustic analysis of silencer within a Dry vacuum pump. Main object is noise reduction of Dry Vacuum Pump using the silencer. First, we measured SPL and Intensity for noise source identification and then, designed for the silencer corresponding with noise character. 4-pole parameter are used for predicting transmission loss which is one of characteristics of silencer when we designed for silencer. Calculated Transmission Loss to change main effective factor and selected to optimal value using Design of Experiment. Finally, noise reduction is estimated to compare existing silencer with optimal silencer.

• Journal of Mechanical Science and Technology
• /
• 제18권11호
• /
• pp.1909-1915
• /
• 2004

The hermetic rotary compressor is one of the most important components of an air conditioning system since it has a great effect on both the performance and the noise and vibration of the system. Noise and vibration occurs due to gas pulsation during the compression process and to unbalanced dynamic force. In order to reduce noise and vibration, it is necessary to identify their sources and transmission path and effectively control them. Many approaches have been tried in order to identify the noise transmission path of a compressor. However, identification has proven to be difficult since the characteristics of compressor noise are complicated due to the interaction of the compressor parts and gas pulsation. In this study, the statistical energy analysis has been used to trace the energy flow in the compressor and to identify the transmission paths from the noise source to the exterior sound field.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2000년도 춘계학술대회논문집
• /
• pp.1615-1620
• /
• 2000

The extensive increase of the rotating speed of HDD (hard disk drive) has improved the performance of HDD. One of drawbacks, however, is that it increase noise level. For the systematic noise control of HDD, it is important to know the way in which each source of HDD contributes to resulting noise. A conventional method for contribution analysis by using statistical information, however, is not proper for HDD. This paper reviews the conventional method, and explains the reason why the method is not proper for HDD, even though it is possible to find the number of independent sources by using statistical information. This paper also shows an experimental result for the identification of the number of independent sources of HDD.

• 한국소음진동공학회논문집
• /
• 제17권10호
• /
• pp.950-957
• /
• 2007

This paper considers acoustic characteristics of silencer within a dry vacuum pump. The main objective is to reduce noise in dry vacuum pump using the new designed silencer. First, SPL and sound intensity are measured for noise source identification and the new model silencer is designed corresponding to noise characteristics. 4-pole parameters are used to predict the transmission loss which is one of the interest characteristics of the new silencer. The calculated transmission loss is then used to change main effective factor and optimal value is selected by using design of experiment. By conducting an experiment, it is proved that the new designed silencer has reduced noise level by 6 dB(A) more than the original one.

• 한국음향학회지
• /
• 제33권3호
• /
• pp.210-215
• /
• 2014

오디오 핑거프린팅 기술은 잡음과 에코 등으로 인한 왜곡에도 성공적으로 음원을 식별해야한다. 이러한 오디오 핑거프린팅 기술을 TV광고식별에 적용하고자 한다. 본 논문은 TV 광고 식별을 위한 강인한 오디오 핑거프린팅 방식을 제안한다. 제안된 방법에서 사용되는 Constant Q 변환 기반에서 추출된 현저한 오디오 피크 쌍 핑거프린트는 실제 다양한 잡음환경에서 오디오 핑거프린팅 시스템의 정확도를 향상시키고, 낮은 복잡도를 가진다. 실험결과는 제안된 방식이 기존의 오디오 핑거프린팅 방식에 비해 다양한 잡음환경에서도 안정적이며 신뢰할 수 있는 검색 정확도를 제공함을 보여준다.

• 대한전자공학회논문지SP
• /
• 제37권6호
• /
• pp.76-82
• /
• 2000

선박의 수중방사소음을 최소화하기 위해서는 주요 소음원인 탑재장비, 추진계통 및 구조물의 전달과정 등에 의해 발생되는 각각의 소음특성 규명이 이루어져야 한다. 그러나 선박의 운항시 계측된 신호는 다중의 소음원과 많은 전달경로에 의해 신호가 중첩되어 발생되고, 소음원과 전달함수를 계측할 수 없는 경우가 많다. 이 논문에서는 캡스트럼 신호처리를 이용한 계측된 응답신호로부터 각각의 소음원과 전달함수 특성을 분리 추출할 수 있는 시험분석기법을 제시하고, 제시된 기법을 수치계산 및 가진실험에 적용하여 검증하고 실제 선박에 적용하여 유용함을 보인다.