• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.4
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• pp.315-323
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• 2013

Tire noise is divided into a road noise(structure-borne noise) and a pattern noise(air-borne noise). Whilst the road noise is caused by the structural vibration of the components on the transfer path from tire to car body, the pattern noise is generated by the air-pumping between tire and road. In this paper, a practical method to estimate the pattern noise inside a passenger car is proposed. The method is developed based on the sound intensity and airborne source quantification. Sound intensity is used for identifying the noise sources of tire. Airborne source quantification is used for estimating the sound pressure level generated by each noise source of a tire. In order to apply the airborne source quantification to the estimation of the sound pressure, the volume velocity of each source should be obtained. It is obtained by using metrics inverse method. The proposed method is successfully applied to the evaluation of the interior noises generated by four types of tires with different pattern each other.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.1
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• pp.42-49
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• 2009

In this paper, an alternative method was introduced to conduct a transfer path analysis for airborne noise. The method used the transfer function matrix composed of acoustic transfer functions that are referenced by the input voltage of a calibration source. A calibration factor which is converting a virtual voltage to source strength was deduced by vibro-acoustical reciprocity theorem. The calibration factor is then multiplied to the virtual input voltage to estimate the operational source strength. Three loudspeakers were used to noise sources of acrylic half car model. The method was applied to airborne noise transfer path analysis of the half car. The estimated source strength by transfer path analysis was compared the deduced source strength by vibro-acoustical reciprocity to verify the method.

• Journal of KSNVE
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• v.11 no.1
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• pp.15-20
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• 2001

홴(fan)은 모터로부터 회전력을 전달받아 공기동력인 풍량과 정압을 발생시켜 발열부품의 냉각 및 환기용으로 산업현장과 가전기기에서 널리 사용되고 있다. 과거 산업현장에서 주로 사용되어지던 송풍기가 가전기기에 적용되면서 홴에 대한 관심이 더욱 증폭되었는데 특히 국내에서 독자적인 소형 홴 연구가 본격적으로 시작된 것도 이 때이다. 가전에서의 홴은 고효율 뿐 만 아니라 주로 저소음화에 대한 연구에 초점이 맞추어져 있는데 이는 기존의 산업현장의 송풍기가 주로 풍량과 정압에 목표를 두고 개발해 왔던 것도 한 이유지만 구조적인 안정성 때문에 소음을 고려한 설계가 한계가 있었기 때문으로 저소음홴에 대한 응용기술이 충분히 발달하지 못했기 때문에 송풍기 기술을 그대로 받아들인 초창기 가전용홴은 소음이 높았다. 또한 가전기기는 모든 연령층이 사용하기 때문에 소음이 큰 제품은 항상 소비자 클레임의 원인이 되기 때문이다.(중략)

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2004.10a
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• pp.361-366
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• 2004

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.10a
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• pp.56-61
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• 1995

많은 공학자들은 기계 재료의 종류 및 형태에 따른 정적, 동적 특성 연구를 수행해 왔다. 특히 산업적으로 그 활용도가 높은 평판 재료에 대한 진동 특성 연구는 많이 이루어졌다. 최근에는 진동 특성을 해석하는 방법도 부분구조합성법, 감도해석법 등의 방법으로 연구가 활발히 이루어지고 있다. 한편 평판의 진동이 공기와 같은 매질로 상호 작용을 하며, 막힘이 없는 공간으로 음향을 방사하는 현상에 대한 연구도 이루어지고 있다. 그러나 평판 재료를 사용하여 기계 구조물을 제작하는 경우 많은 경우에 구조물간 결합에 의해 폐공간이 형성되고 이러한 폐공간에 의해 평판의 진동이 구조-음향 연성 현상이 발생되고, 이에 따라 평판의 진동 특성도 달라지게 된다. 이러한 구조-음향 연성에 대한 연구는 1978년 Wayne B.McDonald와 C.Kearney Barton, 1979년 R.Vaicatis에 의해 폐공간 내로의 음향 전달 현상을 연구하며 이루어졌다. 최근에 연구 동향은 이장명의 FEM과 BEM을 이용한 폐공간 내로의 음향 전달 현상을 연구하였고, V.B.Bokil에 의해 구조-음향 연성된 평판의 모드 해석 방법이 연구되었다. 한편 V.Martin에 의해 능동 소음 제어의 모델링을 좀더 정확히 하기 위해 구조 연성계를 고려한 연구도 수행되었다. 연구 결과 구조-음향 연성에 의한 평판의 고유진동수 변화를 구하였고 이 때에 경계조건을 만족하는 직교다항식을 이용한 Rayleigh-Ritz 방법을 이용하였다. 또한 이러한 해석은 실험과도 매우 잘 일치함을 알 수 있었다.

• Journal of the Society of Naval Architects of Korea
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• v.28 no.2
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• pp.293-306
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• 1991

During the last few years recommendations or regulations concerning permissible noise levels on shirts have been issued by the authorities in most countries. For these reasons the need for useful and accurate noise prediction computer programs has been emphasized. A noise prediction program can make it possible to find the most economical solution to achieve a certain noise requirement. This paper attempts to develop a noise prediction computer program using statistical energy analysis(SEA). In this paper, the SEA is used to predict the sound transmission loss for airborne noise and the vibration amplitude of the panel consisting of ship spaces such as floor, wall, and ceiling for structureborne noise. And in order to verify the prediction, a small passenger vessel, G/T120 tons, is selected. It has been shown that the prediction is capable of giving results in good practical agreement with measurements and therefore it is useful for predicting the nolle levels in ships and establishing the countermeasures at early design stage.

• Proceedings of the KSEE Conference
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• 2006.10a
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• pp.119-140
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• 2006

The rock excavation work by doing blasting breaks the rock by using a shock pressure and gas pressure produced when explosive explodes and the shock wave by shock pressure propagated three-dimensionally from the exploding center is on the decrease notably to the distance, however, $0.5{\sim}20%$ of energy produced by blasting propagates into the ground outside a crack zone by the shape of an elastic wave, on the ground it appears as a ground vibration with a seismic amplitude and a seismic cycle, it is called a blasting vibration. on the other side, what propagated in the air is called a blasting sound. The blasting sound of both means the things which the shock sound within the range the audible frequency($20{\sim}20000Hz$) of the elastic wave in the air influences the response system of a human body, it doesn't harm physically to any structures but influences unreasonably a work accomplishment, such as a work discontinuance due to the outbreak of a public complaint by a mental pain, reduction of a blasting scale, etc.. So, this study is examined at about 20 sites on the installation time and method of soundproofing facilities for reduction of the sound accompanied with a tunnel blasting work.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.7
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• pp.736-745
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• 2009

Fuel cells convert a fuel together with oxygen in a highly efficient electrochemical reaction to electricity and water. Since the electrochemical reaction in the fuel cell stack dose not generate any noise, Fuel cell systems are expected to operated much quieter than combustion engines. However, the tonal noise and the broad band noise caused by a centrifugal compressor and an electric motor cause which is required to feed the ambient air to the cathode of the fuel cell stack with high pressure. In this study, the multi-camber perforated muffler is used to reduce noise. We propose optimized muffler model using an axiomatic design method that optimizes the parameters of perforated muffler while keeping the volume of muffler minimized.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.10a
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• pp.84-90
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• 1996

일반적으로 차실 음향 공동과 차체 팬널이 연성이 되는 계에 대한 소음 연성해석을 위한 해석 모델은 팬널과 공동이 직접적으로 연성이 되는 것으로 모델링되었다. 그러나 루프와 같은 팬널이 차실과 연성이 되는 경우, 루프의 진동은 차실에 직접적으로 전달되지 않고 루프 하단에 존재하는 갭과 내장판을 통하여 차실 소음에 영향을 미친다. 루프와 내장재 사이에 있는 갭의 매질은 주로 공기 도는 흡음재이다. 본 논문에서는 이러한 음향 구조 연성계를 이론적으로 해석 가능한 1차원 모델로 근사화하여 갭의 간격, 갭의 매질 특성, 내장재의 물성치 등의 변화에 따른 공동 내의 음향 응답 특성을 알아보고자 한다. 또한 위 결과를 에어갭을 고려한 3차원 차실 모델에 적용하고, 1/2 차실 모델에 대한 실험을 통하여 에어갭과 내장재의 효과를 검증한다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.249-250
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• 2023

The objective of this study is to evaluate the airborne sound insulation performance between housing units and community facilities during the construction phase. Community facilities adjacent to housing units can lead to noise problems, hence it is necessary to minimize noise transmission during the design phase. However, flanking noise transmitted through gaps of structures, windows, pipes, and other openings may result in substandard sound insulation performance falling below the design standards. Therefore, It is crucial to measure airborne sound insulation in the field during the construction phase. The measurement was conducted using the survey method for the field measurement of the airborne sound insulation in accordance with KS F ISO 10052:2021. Although the noise standards caused by community facilities in apartment complexes are not specified in current laws and regulations, desired noise level was set based on international guidelines for indoor noise. First, the level of noise generated in community facilities was estimated, and then the sound insulation performance was evaluated to determine whether the desired noise level was achieved.