• 소음진동
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• 제6권6호
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• pp.843-849
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• 1996

Locations and emission characteristics of noise source of motor vehicles are great important factors to control the road traffic noise in effective ways. From results of this study on emission characteristics of engine and exhaust noise, we could find that every noise emission of different kind of vehicles has smilar pattern. The main emission locations of engine noise for the front of vehicle became the space between the road surface and bottom of the body and radiator grill, and for the side of vehicle became the space between the road surface and bottom nearby the front wheel. In case of exhaust noise of passenger-car and light truck, all the highest sound intensity level located near surface of road. But it is hard to conclude the height of noise source of driving vehicles with only results of this study. So further studies are needed to check the emission characteristics of noise.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제22회 KOSCI SYMPOSIUM 논문집
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• pp.172-179
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• 2001

Experimental studies have been carried out to find out the characteristics of the heat transfer, combustion emission and noise in the boilers without any extra firing zone for complete combustion of fuel. For the experiments a burner of premixed type and some heat exchangers were designed and manufactured. Also test facilities including a data acquisition system and various measuring devices were set up in order to measure automatically the various temperatures and flow rates of water and combustion gas. Various experiments were performed to find out the heat transfer characteristics as well as combustion emission and noise. In general, the burner which has uniform holes in the burner nozzle plate generates big combustion noise . whistling. The noise reduction method is discussed in this study. Many experimental data such as noise level, the amount of pollutant emission and heat transfer rate for different combination of heat exchangers are given as comparison bases for numerical studies.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.923-927
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• 2003

The aim of this study is to investigate the characteristics and quantity of the noise reduction by pipe material, wrapped pipe with glass wool and installed pipe height The characteristics of noise emission from drain-pipes is as follows. The noise reduction pipe in PVC can reduce noise levels in 7-10㏈ and the cast-iron pipe can reduce in 14㏈compared with the normal PVC pipe. In these days, the glass wool was used for preventing the burst and the noise reduction. But the glass wool for wrapping pipe is not effective to the noise reduction. The characteristics of noise emission from various installed pipe height were measured As the ceiling space of the remodeled building was raised, the noise level was troubled by increasing of the vertical pipe length.

• 한국전자파학회지:전자파기술
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• 제12권1호
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• pp.34-41
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• 2001

Semiconductors performing digital clocking are a main source of radiated emission noise. Therefore, the most secure method of reducing emission noise is to reduce emission radiated from semiconductors; an application of an absorber to the surface of semiconductors is one of these methods, too. However, in reality, it is difficult to achieve as much effect of noise reduction as expected by using only absorber. It is confirmed by experiment in this paper that a loop area within chip has no correlation with radiated emission noise and it is clarified why the existing absorber fails to achieve a satisfactory effect of emission noise reduction. Besides, a new type of chip coating absorber has been developed which can cover up to semiconductor out lead by using ferrite coating material of ferrite/epoxy acrylate substance using only permeability loss out of electromagnetic wave reduction characteristics of materials. As a result of evaluating radiated emission noise by applying this coating absorber to semiconductor device, it could be confirmed that emission noise decreased from about 3 ㏈ up to 20㏈ depending on frequency.

• 한국소음진동공학회논문집
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• 제20권2호
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• pp.160-165
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• 2010

As the various industrial machinery has come into being by development of industrial technology, the productivity of the basic industrial machinery has improved. However, at the same time, noise from various industrial machinery disturbs the quiet environment. There are 35 kinds of the noise emission machinery defined in the noise and vibration control act according to the horse power and the number of machinery. These were classified in 1992, and the characteristics of the noise emission machinery may be different from the past one. So we need to investigate the characteristics of the noise emitted by machinery to control it rightly. We measured sound intensity of 32 noise emission machinery to calculate the sound power levels of those and investigated the characteristics of the sound power level of those according to the frequency. We found that the forging machine, concrete pipe and pile making machine, sawing machine, etc. are noisy. The generator, the concrete pipe and pile making machine, etc. emit the low frequency noise, but the molding machine, the stone cutter, the metal cutter, etc. emit the high frequency noise.

• International Journal of Railway
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• 제4권3호
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• pp.70-73
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• 2011

Controlling the exterior and interior noise emission has become an important issue in the research and development of high speed trains. As the operating speed of the train increases, the noise emission characteristics are expected to deviate from that of the existing trains due to several changes in the basic train layout. For train speed in excess of 350 km/h in particular, the aerodynamic noise component starts to exceed the structure-borne noise component, and even an incremental speed increase is accompanied by a rapid elevation in the noise level. The present study presents an engineering approach for predicting the aerodynamic noise level at the design stage for high speed trains. The experimental noise measurements from test run of Korean high speed train under development are presented as a partial validation of the proposed approach. While the overall aerodynamic noise can be cast in a single power law relationship against the train speed, different parts of the train show power law relationships unique to each component.

• 한국산학기술학회논문지
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• 제19권2호
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• pp.639-643
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• 2018

전자 시스템이 소형화, 이동성의 요구에 따라 전력 변환의 필요성이 계속 증가하고 있다. 또한 전력 변환에는 전력 효율과 함께 전력 변환시스템의 소형화를 위해 적용하는 스위칭에 의한 잡음으로부터 시스템 안정성이 보장되어야 한다. 따라서 전력 변환시 스위칭 잡음을 감소시킬 수 있는 대책이 필수적이다. 본 논문에서는 DC/DC Buck Converter회로를 구성하였고, reference plane을 갖는 4층 PCB 회로 구조에서 부품의 배치를 변경할 경우 발생하는 스위칭 잡음특성을 비교 분석하였다. 또한, Reference Plane을 제거한 양면 PCB회로 구조에서 부품 배치를 달리하였을 경우 스위칭 잡음 특성을 각각 시뮬레이션으로 비교 분석하였다. 그 결과 4층 PCB회로 구조에서는 Current return path에 따라 Radiated Emission 특성이 12dB, Conducted Emission 특성이 7~8dB 감소됨을 확인하였다. 또한 양면 PCB회로 구조에서는 Conducted Emission이 20~25dB 감소됨을 확인하였다. 이로써 전력 변환 회로를 설계할 경우 Current return path의 구성에 따라 잡음 특성을 향상시킬 수 있음을 확인하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.904-908
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• 2008

As the various industrial production machinery has come into being by development of industrial technology, the productivity of the basic industrial production machinery has improved and the international competitiveness of the one of Korea has strengthened. However, at the same time, noise from various industrial production machinery disturbs the quiet environment. There are 35 kinds of the noise emission machinery defined in the noise and vibration control act according to the horse power and the number of machinery. These were classified in 1992 through investigation from 1990 to 1991, and the characteristic of the noise emission machinery may be different from the past one. So we need to investigate the characteristics of the noise emitted by machinery to control it rightly. Also we need to investigate the new noise emission machinery which has come into being recently. In this survey, we measured sound intensity of 32 noise emission machinery to calculate the sound power levels of those and investigated the characteristic of the sound power level of those according to the frequency. From the survey, we found that the forging machine, concrete pipe and pile making machine, sawing machine, etc. are the noisy machinery. And the automatic packing machine, sewing machine, centrifuge, etc. are the silent machinery. Also the generator, the concrete pipe and pile making machine, the printing machine, etc. emit the low frequency noise, and the molding machine, the stone cutter, the metal cutter, etc. emit the high frequency noise. Lastly, we intented to propose the proper guide line of classifying noise emission machinery.

• 한국산학기술학회논문지
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• 제20권1호
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• pp.179-183
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• 2019

전력 변환에는 전력 효율과 함께 전력 변환시스템의 소형화를 위해 적용하는 스위칭에 의한 잡음으로부터 시스템 안정성이 보장되어야 한다. 따라서 전력 변환시 스위칭 잡음을 감소시킬 수 있는 대책이 필수적이다. 따라서 이전 논문에는 MPS사의 MPQ4432 드라이버를 이용하여 DC/DC Buck Converter회로를 구성한 후 이를 reference plane을 갖는 4층 PCB 회로 구조에서 부품의 배치가 서로 다른 경우 발생하는 스위칭 잡음특성을 시뮬레이션 하였다. 본 논문에서는 시뮬레이션을 진행한 서로 다른 두 회로를 제작하여, 시뮬레이션과 동일하게 Conducted Emission특성과 Radiated Emission 특성을 분석하였다. 또한 측정결과와 시뮬레이션 결과와 비교하였다. 그 결과 Current Return Path의 구성에 따라 Conducted Emission특성이 저주파대역에서는 2~9dB, 고주파대역에서는 6~7dB 감소됨을 확인하였다. 그리고 Radiated Emission특성은 9dB 감소됨을 확인하였다. Conducted Emission 시뮬레이션 결과 저주파대역에서 6~7dB이고, 측정 결과는 2~9dB로 다소차이가 있음을 확인하였고, 고주파대역에서는 실험과 시뮬레이션에서 모두 7dB정도임을 확인하였다. 그리고 Radiated Emission은 시뮬레이션에서 12dB 감소를 확인하였지만, 측정결과 9dB의 감소를 확인하였다. 이로써 다소 감소량에는 차이가 확인되었지만 전력변환회로를 설계할 경우 Current return path의 구성에 따라 잡음 특성을 향상시킬 수 있음을 확인하였다.

• 한국소음진동공학회논문집
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• 제17권3호
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• pp.226-234
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• 2007

This study aims to evaluate noise emission from water supply and drain installations in apartment bathroom. These noise were one of the most annoying noise sources in apartment houses. Especially, drain plumbing system have used bellow bathroom ceiling, it was very discomfort to hear the noise in bellow apartment. Noise of closets and faucets were measured which were main noise source, then these noise were evaluate and analyzed the emitting characteristics varying the supplying water pressure. As increasing the water pressure, also total noise level of the water supplying stool noise and faucet noise were increased. Especially the water closet showed remarkably the increasing noise level in middle and high frequency bandwidth, while the noise level of faucets increased in $50\;Hz{\sim}250\;Hz$ of low frequency bandwidth. Vortex closet were favorable to syphon closet, and lever faucet were favorable to conventional lavatory faucet on reducing the noise. Above these results could be used in basic data establishing KS (Korean Standard) for evaluation and rating procedure and measures reducing these noise.