• 한국환경과학회지
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• 제24권5호
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• pp.647-655
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• 2015

In this study, to targeting Songpa of Seoul, were analyzed the effect on the noise mitigation in roadside buffer green spaces. Noise of Songpa Street buffer green space was determined to be higher during the day than at night. In addition, it was most of 60 db or more. However, the noise reduction function of the buffer green was not greatly affected by time. In the case of noise reduction rate, during the day time it was the order of the mounding type (18.14%)> plain type (5.73%)> slope type (4.08%), And, in the case of night time, it was the order of the mounding type (11.29%)> slope type (10.22%)> plain type (4.42%). Noise reduction rate, all of the daytime, was the highest in the mounding type. As a result of the factors on the amount of reduction of noise, More physical structure is mounding type, green structure is the stratification of green space, and the number of individuals is large, the higher the tree planting density, it is determined that the noise reduction effect is high. Also, factors affecting the noise reduction effect of the day and night were different.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.101.2-101.2
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• 2015

급속한 산업화로 인하여 에너지 부족 문제가 대두되고 있는 가운데 에너지 저감 기술의 개발이 요구되고 있다. 국내 반도체 공정의 배기계통에서 소비되는 에너지는 전체 공정에 소비되는 에너지중 상당량에 달하며 10%의 에너지 절감은 연간 1000억원 이상의 비용절감 효과를 기대할 수 있다. 반도체 공정 배기계통은 진공펌프의 특성, 챔버의 부피, 도관의 구조(직경, 길이, 형상), 진공재료의 기체방출 등 여러 가지 요소의 복합적인 영향으로 그 상태가 달라지므로 보다 효과적인 공정의 운용과 에너지 절감을 위해 반도체 공정의 복합 상태 진단기술 개발이 요구되고 있으며 그중 큰 비중을 차지하는 드라이펌프의 실시간 모니터링 기술의 개발이 시급하다. 본 연구에서는 반도체 공정의 복합 상태 진단기술 개발에 대한 기초 연구로서 반도체 공정 배기계통의 conductance 및 유량 변화에 대한 드라이펌프의 특성을 이론적 계산으로 얻어진 결과와 실험을 통하여 얻어진 결과를 비교, 분석하였다. 진공펌프의 기본 특성은 한국표준과학연구원에서 국제규격에 따라 도달진공도, 배기속도, 소비전력, gas load, 소음, 진동 등을 분석하였고, 나노종합기술원의 PECVD 장비(chamber A: amorphous silicon 및 loadlock chamber)에 챔버의 부피, 도관의 구조, 공정가스의 유량 등을 측정하여 simulation 하였으며, 실제 측정값은 LabVIEW 프로그래밍으로 자동화 된 MFC를 이용하여 실제 공정 상태를 모사하였다. 실험은 PECVD의 특성을 고려하여 질소분위기에서 CDG (Capacitance Diaphragm Gauge)를 사용하였다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권3호
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• pp.97-103
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• 1999

This paper investigates reduction of acoustic noise and cogging torque in a BLDC motor with larger stator slot open width. Using energy method, cogging torque is analytically determined with airgap MMF function and airgap permeance function and confirmed by FEM analysis. It shows that the cogging torque is firstly governed by NL GNL BNL with the fundamental period of NL, where NL is the least common multiple of the number of slots and the number of poles, GNL, airgap permeance function and BNL, airgap MMF function. It also shows that there exist several tooth width which minimizes the cogging torque, for the motors that smaller slot open width or stator teeth notching is not available. And it proposes a teeth pairing with two different tooth width which can effectively eliminate the cogging torque and thus the acoustic noise. Experimental results show that the proposed teeth pairing reduces the cogging torque by 85% and the acoustic noise by 3.1dB.

• 대한기계학회논문집B
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• 제20권7호
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• pp.2375-2385
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• 1996

As a compression wave is emitted from a duct, an impulsive wave generates and causes an impulsive noise that is at present a serious environmental noise pollution. In order to clarify the acoustic characteristics of the noise and to reduce their pressure levels, a series of model experiments were conducted on the impulsive waves emitted from an open end of a shock tube. The impulsive waves with various intensities were obtained by controlling the operation pressure ratio of the shock tube. Various kinds of silencers such as the exit boxes with baffle plates, were applied to the duct exit to reduce the impulsive noises. The effects of geometry of silencers and shock Mach number on the noise reduction were clarified. From the measurements of sound pressure level, it was found that installing the baffle plate into the exit box is effective in lowering the noise level at far fields, and that the recommendable geometries of silencer are L/D=1, H/D=1 and H/D=0.75.

• 터널과지하공간
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• 제7권2호
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• pp.116-129
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• 1997

The objective of this study is to predict the minimization effect of the noise and vibration during the construction and the train operation regarding to the design modification of the Taegu Subway Line No. 1. It was suggested optimal control blasting methods to reduce the causing vibration Nuance to the resident in City Taegu and also proposed the better governing method to decrease the environmental hazard to the near buildings and residents during the train operation. When the high-density gaseous reaction of explosion products exerts a high pressure in motion outward, a dynamic stress field will be created in the surrounding buildings. Therefore, in the region close to the charge, permanent damage begins to occur at a great critical level of partial velocity, that is difficult from different structure as working conditions. It is reliable to predict that the damages could be reduced if we know the peak velocity and the exact reasons through the conducting of detail studies of structural analysis of the related buildings with the optimal blasting designs. A blasting technique should be deemed to take advantage of the reduction of damage of the surrounding rocks and structures to improve the in-city blasting. This is a typical in-city blasting operation where success depends on closely controlling the ground vibrations in case of better designed blasting methods. There are techniques that can be applied to prevent large vibrations from damaging the important buildings through the Route Modification of the Taegu Subway Line No. 1.

• 한국전자통신학회논문지
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• 제11권4호
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• pp.379-386
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• 2016

고속철도를 운영할 뿐 아니라, 고속열차를 생산하는 우리나라는 고속철도를 효율적으로 운용하기 위해 각 분야에서 승차감 향상, 주요부품 자동진단, 차상 전기검측, 소음저감 등 여러 가지 기술을 개발하고 있다. 본 논문은 그 중에서도 철도 무선통신분야의 기술을 이해하기 위해, 유럽과 중국 및 미국의 철도 무선통신시스템의 운용현황을 설명하고, 국내 철도에도 적용될 철도용 LTE 시스템의 기술현황을 소개한다. 아울러 현재 운용하고 있는 국내 철도무선통신망 현황과 4세대 무선통신망에 대한 국가연구개발사업의 개략 및 고속철도 현장에서의 시험계획을 소개한다.

• 전기학회논문지
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• 제57권11호
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• pp.1962-1969
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• 2008

According to the increase of power demand and expansion of downtown, it is necessary to install transformers additionally in operating substations and construct substations in residential area. But the public complaint is increased due to the transformer noise of the substation. KEPCO has used a vibration preventing pad, various soundproof walls and an encloser to transformers in outdoor substations, and a soundproof door, shutter and wind-path soundproof equipment in indoor substations to block the sound propagation of the transformers. But these noise reduction methods are not satisfied. It should be considered to reduce transformer noise itself. In this paper, we investigated core noise reduction techniques to develope a low noise transformer. The techniques to reduce core noise of the transformer are application of high permeability grain oriented silicon sheets, decrease of magnetic flux density of core, application of 6step-lap core stacking method, improvement of core binding method(binding addition, band fixing) and application of rubber damper in oder to reduce transmission of core vibration, etc.

• 동력기계공학회지
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• 제6권3호
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• pp.57-63
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• 2002

This paper describes the acoustic analysis of mid duty truck. The focus of the analysis is on structure borne engine noise with major contributions of 2nd order. It has been previously recognized that the noise contribution of each transfer path of structure borne noise can be varied with the charateristics of each mounts and vibro acoustic sensitivity of car body. The structure of car body will be split up into three major sub components, which are modeled separately, the engine, the frame and the cab. The acoustic performance is evaluated on three levels: engine to frame transfer, frame to cab transfer, and panel contribution from cab to driver. In order to perform these analyses, analytical models are created for the engine, frame, cab and acoustic cavity. The models are linked through a coupled fluid structure calculation, and through FRF Based Substructuring for the structural couplings. Based on the structural coupling calculations, a transfer path analysis is performed to identify the most important transfer paths. These paths are then the focussing points for applying modifications to the structure or the mount system. Finally, a number of modification are proposed and their effect is quantified.

• 전기학회논문지
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• 제57권10호
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• pp.1759-1766
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• 2008

According to the increase of power demand and expansion of downtown, it is necessary to install transformers additionally in operating substations and construct substations in residential area. But the public complaint has been increased due to the transformer noise of the substation. KEPCO has used a vibration preventing pad, various soundproof walls and an encloser to transformers in outdoor substations, and a soundproof door, shutter and wind-path soundproof equipment in indoor substations to block the sound propagation from the transformers. But these noise reduction methods are not satisfied. It should be considered to reduce transformer noise itself. In this paper, we investigated tank noise reduction techniques to develope a low noise transformer. According to the mode analysis of transformer tank, we found out characteristics and locations of noise on the tank, and it's nature vibration was also analysed. On the basis of these analysis, reinforcement equipment was installed around transformer tank, and ellipse shape tank was changed to round shape tank. The effect of noise reduction was evaluated using noise generation source.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.57.1-57.1
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• 2011

본 논문에서는 소음을 저감하고 구조적 안전도를 향상시키기 위하여 10kW급 소형 복합재 풍력터빈 블레이드를 해석, 설계하였다. 풍력터빈 블레이드 설계의 기본 사항에 맞추어 블레이드의 스팬 길이는 약 4m, 중량은 30kg 내외가 되도록 설정하였다. 풍력발전기용 블레이드는 경량화가 중요하므로 유리섬유복합재 (glass fiber reinforce pastics), 탄소섬유복합재 (carbon fiber reinforced plastics)가 사용되었다. 본 설계에서는 Carbon prepreg (WSN3KY), Carbon UD(UIN150c), E-glass 등을 사용하였다. 상용 유한요소 프로그램인 NASTRAN을 이용해 Carbon prepreg (WSN3KY), Carbon UD (UIN150c)의 탄소섬유복합재만으로 구성된 블레이드 구조해석을 수행한 결과 중량 조건 및 강도의 안전도는 충족되었으나, 높은 가격을 감안하여 E-glass와 조합하여 블레이드를 재설계할 예정이다. 이번 설계는 소형 풍력발전용 블레이드 설계이므로 좌굴은 고려하지 않았으며, 향후 필요에 따라서 좌굴 및 피로해석도 수행하여 검증할 예정이다. 그리고 블레이드가 복합재로 구성되면 감쇠력이 감소할 가능성이 있다. 탄소섬유복합재로만 구성된 블레이드 구조해석에서도 최대 40cm의 변형이 예측되었으며, 감쇠값 저하 문제도 고려하여야 될 것 같아 BEMT (Blade Element Momentum Theory) 공력모델을 이용해 구조-유체 연성 결합 해석을 수행할 계획이다.