• 한국소음진동공학회논문집
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• 제22권1호
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• pp.61-73
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• 2012

The paper presents the novel approach to solve some problems occurred in application of the genetic algorithm to the determination of the optimal tire pattern sequence in order to reduce the tire air-pumping noise which is generated by the repeated compression and expansion of the air cavity between tire pattern and road surface. The genetic algorithm has been used to find the optimal tire pattern sequence having a low level of tire air-pumping noise using the image based air-pumping model. In the genetic algorithm used in the previous researches, there are some problems in the encoding structure and the selection of objective function. The paper proposed single encoding element with five integers, divergent objective function based on evolutionary process and the optimal evolutionary rate based on Shannon entropy to solve the problems. The results of the proposed genetic algorithm with evolutionary process are compared with those of the randomized algorithm without evolutionary process on the two-dimensional normal distribution. It is confirmed that the genetic algorithm is more effective to reduce the peak value of the predicted tire air-pumping noise and the consistency and cohesion of the obtained simulation results are also improved in terms of probability.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.698-698
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• 2014

According to the analysis of special medical examination and work environment monitoring data, the rate of C1 and D1 on noise hazard exceeded 90% among those of total hazardous factors. The rate of company exceeding noise exposure limit was also more than 90%. The analysis result shows that main ages diagnosed with C1 and D1 was age of 50s. The majority scale company having workers diagnosed with C1 and D1 was the companies employing 5~49 workers. Types of industries which have a large number of companies exceeding noise exposure limit were automobile and trailer manufacturing, metal processing industry and primary metal manufacturing. A large number of work processes exceeding noise exposure limit were forming and processing work, cutting and bending work and grinding. To reduce the number of company exceeding noise exposure limit, the reduction counterplan should be focused on the type of industry and the work process which exceeded noise exposure limit frequently. However, the reduction counterplan is preemptively necessary to the type of industry and the work process which exceeded noise exposure limit consecutively if the purpose of reduction counterplan is not to merely reduce the number of company exceeding noise exposure limit but to abate workers' suffering from noise.

• 대한기계학회논문집
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• 제18권5호
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• pp.1347-1354
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• 1994

This paper deals with the experimental research, including measurement and analysis and field survey, on the causes of occurring noise defective gear boxes in hoist production plant in order to reduce the fraction of their occurrence. In this reserch following investigations are performed : measurement and gear-boxes, examination of each machining process of production, measurement and analysis of dimensional accuracy of each part, comparative vibration test with exchanging inaccurate parts. From these investigations, it is found that the machining accuracy of pinion gear tooth thickness is the most sensitive factor of noise problem. By maintaining the tooth thickness error within 0.05 mm tolerance in the gear cutting process, the fraction of noise defective gear-boxes are greatly reduced to less than 2%, where the usual rate of it has been 20-50%.

• 한국기계가공학회지
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• 제8권1호
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• pp.71-76
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• 2009

In a running blower, there are various exciting forces which can generate noise. The noise of an running industrial fan or blower depends on the structure of a fan, the machining accuracy of each element, and assembled conditions. Many studies have been carried out to reduce the noise of it. In this study, 3-hole buffs are used in pipe of blower to study the influence the number and position of buffs on the noise reduction at inlet and outlet in pipe. Commercial engineering software ANSYS and SYSNOISE were employed to analyze the characteristics and reduction ratio of pressure. It is concluded that optimal position and number of buffs in pipe of blower to show the least reduction ratio of pressure.

• 한국기계가공학회지
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• 제20권6호
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• pp.76-81
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• 2021

A plastic noise barrier is a structure installed to minimize noise, and it is composed of the main plate, sound-absorbing plate, and sound-absorbing material. Plastic noise barrier structures have several advantages compared to other products, such as light weight, anticorrosion, durability, easy assembly, rapid construction, and low costs. In this study, the main and sound-absorbing plates were manufactured through extrusion molding, and the sound-absorbing plate was finished with a press to improve the conventional injection molding. Extrusion molding dies and punch dies were designed, and a profile extrusion-molding system was developed. Thus, inexpensive and efficient sound-absorbing and main plates can be produced, and the noise barrier structure can be assembled rapidly. Additionally, a noise barrier structure with extended service life and excellent quality can be constructed by creating uniform free space to accommodate increased temperatures after assembly and installation.

• 한국건축시공학회지
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• 제14권5호
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• pp.467-476
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• 2014

최근 건설공사의 기계화로 인한 많은 장비 투입으로 인하여 주변 주민들이 현장 소음에 인한 피해보상을 요구하는 민원이 증가하고 있다. 하지만 현장소음은 예방차원이 아닌 공사 진행과정에서만 제한적으로 관리되며 민원이 발생하고 나서야 대부분의 대처가 이루어지고 있는 실정이다. 또한, 이러한 민원을 해결하기 위해서는 비용과 시간이 과다하게 소요되는데 이는 건설사에 부정적인 영향을 미치게 된다. 이에 본 연구는 착공 전부터 계획된 공사기간과 장비투입 조건을 활용하여 최적 공사비를 찾는 알고리즘을 제안하고 최적 공정표를 도출할 수 있는 스케줄링 프로세스 모델을 개발하는 데 그 목적이 있다. 또한, 이를 활용하여 현장관리자가 공사계획 수립 시 소음발생 여부에 따라 민원이 발생할 때 예측되는 비용정보 및 소음제한에 따른 공사비와 공사기간의 변화 정도를 비교 분석함으로써 보다 합리적이고 효율적인 공사 관리를 수행할 수 있도록 한다.

• 대한전자공학회논문지SP
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• 제45권5호
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• pp.95-102
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• 2008

이 논문은 고강도매질 CR(Computed Radiography) 영상의 잡음을 모델링하는 적절한 접근법을 제시한다. 잡음 유형의 통계적이고 비선형적 특성이 구체적으로 고안되었다. CR영상은 컴퓨터 처리에 의해 코드화되기 이전 이미 훼손된다. 다양한 형태의 잡음은 비록 디지털화된 상태로 검출된다 하더라도 통상 방사선 영상을 오염시킨다. 양자 방출시의 포아송 분포는 CR 영상판에서의 광자 분포에서 포아송 잡음 분포를 항상 유지하지 않는다. 그 통계적 특성은 재질 특성에 의해 상대적이며 경우의존적이다. 통계적 잡음모델링 과정에서 통상적인 포아송, 이항 내지는 가우스 통계분포의 가정이 고려되었으며 아울러 비선형 효과 또한 포함시켰다. 이는 잡음 영역의 고저 전 방사선량에 걸쳐 추정하는 해석적 모델을 구현한다. 그리고 이 분석적 접근은 고강도 강판튜브 스텝웨지의 방사선측정실험을 통해 관측한 CR 영상데이터에서 구현되었다. 그 결과는 매질의 두께변화에 따른 잡음의 일관성, 잡음분포특성, SNR 및 비선형 보간을 측정하는 상호비교의 파라미터연구에 유용하다.

• 한국기계가공학회지
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• 제14권1호
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• pp.57-62
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• 2015

The wet brakes used on a forklift often produce noise upon engagement. The elimination or reduction of this squeal noise is an important task for the improvement of the comfort of those operating these machines. In this paper, a test rig was developed for the testing of brake noise, and the squeal noise was measured with this apparatus. Automatic transmission fluid and grooves in the material of the friction-plate pad were found to be the main factors causing squeal noise. In order to identify the characteristics of this type of noise, signal analyses of the noise were conducted using different frequency spectra. The experimental results showed that the viscosity of the automatic transmission fluid and the groove pattern on the friction-plate pad largely affected the reduction of the wet brake squeal noise made by an industrial forklift.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2018년도 추계학술대회
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• pp.255-257
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• 2018

최근 다양한 분야에서 영상매체의 사용 빈도가 증가함에 따라 신호처리의 중요성이 높아지고 있다. 하지만 송수신 과정에서 많은 종류의 잡음이 발생하며 신호의 정보에 영향을 미치고 있으며, 이러한 이유로 잡음 제거를 전처리 과정으로서 필수적으로 행한다. 본 논문에서는 임펄스 잡음과 AWGN이 혼합된 잡음을 제거하기 위한 알고리즘을 제안하였다. 제안한 알고리즘은 효율적인 잡음 제거를 위해 잡음 판단과 화소 변화를 통해 영상을 복원하였으며, 기존 방법과 달리 두 잡음의 영향을 모두 최소화하여 잡음을 제거하는 모습을 보였다. 시뮬레이션 결과 우수한 잡음제거 특성을 나타내었으며, 객관적인 판단을 위해 PSNR 등을 이용하여 비교 및 분석하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.353-356
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• 2003

Acoustic holography is adopted in identifying the noise sources of a vehicle's underbody. Wind noise from a vehicle's underbody accounts for a large portion of the overall noise level due to the complex flow structure. Current study presents the development process of acoustic holography in the vehicle underbody, and discusses the results obtained using the method. Difficulties associated with using acoustic holography as well as the implication of the results regarding future noise reduction possibilities are discussed.