• 한국소음진동공학회논문집
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• 제23권9호
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• pp.823-830
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• 2013

The purpose of this study is to develop a noise reduction device installed at the top of noise barrier for further decreasing of noise level of 400 km/h class high-speed railroad. For this, the frequency spectrum of 400 km/h class high-speed railroad was analyzed through the field noise test, and the tuning frequency was determined to design a noise reduction device. The noise reduction device was designed to have noise reduction performance of at least 3 dB(A) using the prediction method(2D BEM) and through the laboratory test with the prototype. Finally, the outdoor test showed that this device could decrease noise level of 400 km/h class high-speed railroad even more than 3 dB(A).

• 환경영향평가
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• 제20권6호
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• pp.787-795
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• 2011

Noise barrier is generally used with welding of joint rail for railway noise reduction in our country. But the noise barrier for high speed railway has weak point in low frequencies about 315Hz band. In this study, For developing of Interference-type Noise Reduction Device(INRD), acoustic analysis were performed using commercial software. For verifying the improvement in the noise reduction, noise measurement before and after installing of INRD were performed in Anechoic Chamber. From these acoustic analysis and noise measurement, it was known that developed INRD has a good noise reduction performance and can be used efficiently with conventional noise barrier.

• 한국소음진동공학회논문집
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• 제23권6호
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• pp.495-501
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• 2013

This paper deals with noise reduction on a light source driving board in a projector. We analyze causes of noise/vibration in the circuit with the present increasing use of LD and LED driving boards. The main source of noise is the MLCC in the driving board. Our aim is to investigate how the mechanical arrangement of the circuit elements affects noise reduction. The result of our experiment shows that noise can be reduced by symmetrical arrangement and slots in PCB. This result is expected to facilitate a variety of applications for manufactures without a need to change circuit elements.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.767-770
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• 2002

Reduction of the propagation noise generated during pass-by of KTX by noise barrier was measured and analysed for the two kinds of top-shaped noise reduction devices; one as a plywood board and the other as a PVC pipe were placed periodically. The height and length of reference noise barrier are 2.4 m and 50 m, respectively. The noise reduction with and without noise reduction devices was investigated.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 춘계학술대회 논문집
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• pp.625-629
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• 2014

For the purpose of the acoustic performance evaluation of noise reduction device(NRD) installed at the top of noise barrier for further decreasing of noise level of 400km/h class high-speed railroad(HEMU), the acoustic performance test method using speaker instead of really running railway vehicle was suggested in this paper. For this, noise source location and frequency spectrum of HEMU was analyzed through the field noise test. These data were used for the determination of speaker's installation positions and frequency correction values applied to the speaker noise source. And, 400 meters long NRD was installed at the site where HEMU will be running at a speed of 400km/h. Finally, the outdoor speaker test with and without NRD showed that this NRD could decrease noise level even more than 3dB(A). In the future, the acoustic performance results of NRD conducted with speaker test will be compared with that of field test for HEMU running at a speed of 400km/h.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.134-139
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• 2002

We have made known the study of shape development of interference device for vehicle noise control. It's primary object greatly attenuate the noise due to transport vehicle by small products installed on the noise barrier edge. Also, it is able to improve the insertion loss of a noise barrier without increasing the height. The present time, we set up a newly manufactured products on the noise barrier edge and testify to it's the performance make use of an experiment and evaluation for the reduction of highway traffic noise. In this paper the frequency characteristic of interference device of noise barriers with attached newly developed products in terms of shape, absorptive material and split panel, are examined using field test at highway.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.376.1-376
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• 2002

Reduction of the propagation noise generated during pass-by of KTX by noise barrier was measured and analysed fur the two kinds of top-shaped noise reduction devices; one as a plywood board and the other as a PVC pipe were placed periodically. The height and length of reference noise barrier are 2.4 m and 50 m, respectively. The noise reduction with and without noise reduction devices was investigated. (omitted)

• 대한환경공학회지
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• 제39권12호
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• pp.679-684
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• 2017

고속열차의 설계 및 운행기술이 발전하면서 고속철도의 운행속도가 빠르게 증속되고 있다. 반면 증속 시 발생하는 소음으로 인해 고속철도 연변의 주거지역 등에서는 많은 소음문제가 발생하고 있으며, 고속철도 소음에 대한 민원도 지속적인 증가추세에 있다. 향후 고속철도가 원활히 설계속도대로 운행되기 위해서는 고속철도의 방사소음특성에 적합한 소음예측기술 및 저감기술이 개발되어야 한다. 이와 같은 요구에 부합하기 위해, 400 km/h 고속철도 인프라 연구가 수년에 걸쳐 진행되었다. 이 연구를 통해 신뢰성을 갖는 고속철도 소음예측평가 기술이 개발되었고, 현재 소음저감기술의 단점을 극복하기 위한 핵심방음장치가 개발되었다. 본 연구의 궁극적인 목적은 고속철도 환경소음을 줄이기 위해 개발된 선로 변 벽체 상단에 설치되는 상단장치의 소음성능평가 및 풍압안전성 검증에 관한 것이다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 춘계학술대회 논문집
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• pp.577-583
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• 2002

We have made known the study of shape development of interference device for vehicle noise control. It's primary object greatly attenuate the noise due to transport vehicle by small products installed on the noise barrier edge. Also, it is able to improve the insertion loss of a noise barrier without increasing the height of noise barrier. The present time, we set up a newly manufactured products on the noise barrier edge and testify to it's the performance use of an experiment and evaluation for the reduction of railway noise. In this paper the frequency characteristic of interference device of noise barriers with attached newly developed products in terms of shape, absorptive material and split panel, are examined using field test around of railroad.

• 한국소음진동공학회논문집
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• 제17권6호
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• pp.477-483
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• 2007

Major noise source in high speed rotating optical disk drives (CD and DVD-ROM) arises due to the high-speed airflow produced from the upper and lower surfaces on the rotating disk. The present paper deals with the experimental approach how to identify the noise source based on the fundamental principles of aeroacoustics and to propose a reduction method of the noise source. The CD-ROM device is composed of disk, window tray, motors at the bottom place and electronic circuit plate also located below the window plate. The window is cut in the tray to read the disk information using the optical device located below the tray and moving linearly from the center of the disk through the end of the disk. All components are possible noise generators. Experimental studies were carried out in the anechoic room with various design modifications, such as tray geometry, window size and hole location on tray, to identify the major aerodynamic noise source and significant reductions of the aerodynamic noise were obtained.