덕트 밖에서 계산된 삽입 손실을 고려한 머플러 최적 설계

이종겸(Jong Kyeom Lee),오기승(Kee Seung Oh),이진우(Jin Woo Lee) 대한기계학회 2016 大韓機械學會論文集A Vol.40 No.5

머플러의 확장방 내부에 격벽을 최적으로 배치하기 위한 음향 위상 최적화 문제를 정식화 한다. 목표 주파수에서 삽입 손실의 하한 값을 제한하며, 격벽의 부피를 목적 함수로 선정하여 최소화한다. 기존 연구에서는 투과 손실이나 덕트 내부에서 계산된 삽입 손실을 머플러의 소음 저감 특성으로 사용하였으나, 본 연구에서는 덕트 외부에서 계산된 삽입 손실을 사용한다. 음향 해석을 위해 유한 요소 모델이 사용되고, 각 유한 요소에 입사된 음파의 투과 정도는 “0”과 “1” 사이에서 연속적으로 변화하는 설계 변수의 함수에 의해 결정된다. 입사파를 모두 반사시키는 강체들이 격벽을 형성한다. 목적 주파수와 허용하는 삽입손실 값에 따른 최적 위상을 비교한다. In this study, we formulate an acoustical topology optimization problem to optimally design a partition layout inside the expansion chamber of a muffler. The lower-limit insertion loss value at a target frequency is constrained, and the partition volume is selected as an object function. In this study, we calculate the insertion loss outside the duct, while to determine the noise-attenuation performance, we use the insertion loss value calculated inside the duct or transmission loss value obtained in a previous study. We employ the finite-element model for acoustical analysis, and we determine the transmission of an incident acoustic wave through each finite element using the functions of design variables that change continuously between “0” and “1.” The rigid body elements, which totally reflect incident waves, build up partitions. Finally, we compare optimal topologies that depend on the target frequency and the allowed lower-limit value of insertion loss.

기포층 음향 삽입손실 연구: 기포커튼과 에어마스커

박철수,정소원,김건도,문일성,임근태 한국음향학회 2020 韓國音響學會誌 Vol.39 No.4

해양구조물의 파일링 소음을 줄이기 위한 기포커튼과 선체 진동에 의한 수중방사소음 차단을 위한 에어마스커에 대하여 각각의 삽입손실 해석해를 유도하였다. 해석해를 구하기 위해 기포커튼과 에어마스커를 각각 ‘유체-기포층-유체’ 그리고 ‘진공-평판-유체-기포층-유체’의 단순 모델로 가정하였고, 각 모델에서 해당 기포층을 복소수 형태의파수와 임피던스로 규정된 유효매질로 치환하였다. 수치 모의를 통해 기포의 분포, 기포율, 그리고 기포층의 두께에따른 삽입손실의 특성을 살펴보았다. This paper derives the insertion loss for the bubble layer of an air bubble curtain and an air masker which are used to reduce ocean anthropogenic noise such as the piling noise and the ship noise. The air bubble curtain is considered as a ‘fluid-air bubble layer-fluid’ model and the environment for the air masker is simplified as an ‘vacuum-thin plate-fluid-air bubble layer-fluid’ model. The air bubble layer in each model is assumed as the effective medium which has the complex wavenumber and the complex impedance corresponding to the bubble population distribution. The numerical simulations are performed to examine the insertion loss depending on the bubble population, the void fraction, and the thickness of the layer.

삽입손실 개선을 위한 링 접촉식 구조의 L대역 로터리조인트 설계

나재현(Jae-Hyun Na),노돈석(Don-Suk Roh),김동길(Dong-Gil Kim) 한국전자통신학회 2019 한국전자통신학회 논문지 Vol.14 No.1

본 논문에서는 추적 레이더시스템의 핵심부품인 L대역 로터리조인트의 설계를 다룬다. 로터리조인트는 추적시스템 안테나 회전부에 장착되어 회전하는 안테나와 고정된 신호처리부를 연결하는 구성품으로 안테나의 회전시에도 꼬임이 없이 RF신호를 원활하게 전달하는 주요부품이다. 로터리조인트의 신호 삽입손실을 개선하기 위해, 유전체 종류, 급전분배링 형상 및 유전체 형상 등을 다양하게 수정하였다. 제안한 로터로조인트는 해외 도입품과 비교하여 향상된 성능을 확인하였다. 도입품 로터리조인트의 최대 삽입손실은 1.26dB이었으나, 본 논문에서 제안한 로터리조인트의 최대 삽입손실은 0.68dB로 도입품 대비 약 46%정도 개선되는 것을 확인하였다. This paper deals with the design of the L-band rotary joint, which is a core part of the tracking radar system. The rotary joint is a part that is mounted on the rotating parts of the tracking system antenna, which smoothly transmits RF signals with minimizing signal insertion loss. To improve the insertion loss of rotary joint, 1) dielectric materials, 2) design of distribution ring and 3)dielectric shape are studied. The performance of proposed rotary joint is compared with the conventional product. The prototype rotary joint showed a max insertion loss of 0.68dB, that is improved about 46% compare with conventional product which insertion loss was 1.26dB.

음향 루우버의 삽입손실 예측연구

유왕선(Wang Seon Yu),김태민(Tae-Min Kim),김정태(Jeung-Tae Kim) 한국철도학회 2017 한국철도학회 학술발표대회논문집 Vol.2017 No.05

본 연구는 음향 루우버가 설치되어 있는 개방형 방음터널의 음향효과를 예측하기 위하여, 광음향기법을 이용하였다. 음향 루우버의 개구율이 36 %인 조건에서, 음향 루우버의 삽입손실을 잔향실에서 측정된 결과와 비교 분석하였다. 본 연구에서는 해석 모델 구성 시 동일한 잔향실을 모델링 하였으며, 소음원과 수음점의 위치를 ISO 규격에 따라 동일하게 구성하였다. 해석 결과 광음향기법을 이용한 삽입손실 예측 방법이 측정 결과 대비 유사한 것으로 분석되었으며, 추후 흡음재 종류에 따른 삽입손실 영향을 분석할 예정이다. In this study, an acoustics performance for a louver was predicted and analyzed by using a ray tracing method. As a part of the study on the partial opening type of the soundproof tunnel, the proposed aperture ratio of acoustic louver was specified as 36% opening area ratio. Since an insertion loss of the acoustic louver was measured in the reverberation chamber, the same reverberation room was modelled in the simulation. The sound source and the receiving points were constructed according to the ISO standard. The result shows that the estimation of the insertion loss based on the ray tracing method was be similar to the measured data. Extra insertion loss effect due to the sound absorbing material attachment is planning to be studied.

방음벽 상부구조물의 형상에 따른 삽입손실 비교

김선도 ( Seon Do Kim ),정제훈 ( Je Hoon Jeong ),한찬훈 ( Chan Hoon Haan ) 충북대학교 건설기술연구소 2015 建設技術論文集 Vol.34 No.2

건축물에 발전에 따라서 주거환경은 도시화, 산업화로 인한 열섬현상과 공기질 저하, 교통 소음 및 재해 환경요염 및 녹지면적의 절대적인 부족 등의 다양한 문제로 병들어 있다. 특히 소음으로 인한 문제는 쾌적한 주거환경을 요구하는 거주자에게 상당한 불쾌감과 스트레스를 주고 있다. 이러한 현상들은 삶의 질이 윤택해짐에 따라서 불쾌감의 정도가 끊임없이 올라가고 있다. 때문에 소음에 관한 규정이 생기고, 이에 따라서 건축은 변화하고 있는 시점이다. 소음 및 진동에 관한 민원사항의 대부분은 교통 소음에 관한 것으로써 이를 위하여 주택가, 고속도로 주면, 공장 지대, 학교 주변 등을 중심으로 방음벽의 설치가 꾸준히 증가하는 추세이다. 하지만 이러한 방음벽 설치의 확대가 모든 소음을 저감하는 것은 아니다. 분명 방음벽은 도로교통 소음의 저감에 효과를 보기는 하지만 소음저감량은 이론상 최대 15~20dB(A)까지로 제한적일 수밖에 없다. 하지만 이러한 건축물의 증가함에 따라서 사람들은 쾌적성을 요구하고 있다. 방음벽의 소음저감량을 높이기 위해서는 방음벽의 높이를 증가시키는 방법이 있지만 법규에 따라서는 높이에 한계가 있다. 이러한 한계를 극복하기 위해서는 방음벽 상부구조물을 설치하여서 소음저감량을 높여야 한다. 방음벽 상부구조물을 설치하면서 형태에 따라서 삽입손실량을 비교하고 최적의 형태의 방음벽 상부구조물을 찾고자 하였다. Noise barriers are widely used in and around the residential area. However, the noise reduction efficiency is not satisfied with the comfort of residents. In order to increase the noise reduction of the noise barriers, various upper structures have been introduced and used nowadays. The present study investigates the insertion losses of the noise barriers with different shapes of upper structure. Seven different upper structures were designed and applied to a noise barrier under same conditions. Computer simulations were undertaken to calculate the insertion losses using 3-D models of noise barriers. As a result, It was found that insertion loss of noise barriers with Y and T -shaped upper structures is greater than those with ㄱ and L-shaped upper structures. It is because the Y and T-shaped upper structure overgrow along the axis of the noise sources and measurement points while ㄱ and L -shaped upper structures stretch to one side of noise barrier.

환형 공명기가 설치된 소음기 설계 및 성능 시험

김봉기(Kim, Bong-Ki),김상렬(Kim, Sang-Ryul),이성현(Lee, Seong-Hyun),이종화(Lee, Jong-Hwa),이해성(Lee, Hae-Seong) 한국소음진동공학회 2011 한국소음진동공학회 논문집 Vol.21 No.4

In this study, ring-shaped acoustic resonators were proposed to be installed in a silencer to increase the acoustic performance of silencer in the low-frequency range. Evaluation of noise reduction performance of acoustic resonator arrays was carried out by measuring the random-incidence absorption coefficient. It was found that the absorption coefficient of resonator array was measured up to 1 at 125 Hz of 1/3-octave band center frequency. Insertion losses of silencers with ring-shaped acoustic resonator arrays were measured based on ISO 7235. The results were shown that the ring-shaped resonator could increase the insertion loss up to 13 dB without flow, whereas 7 dB when flow speed reached 15 m/s. As increasing the flow speed above 15 m/s, the effect of acoustic resonator decreased due to the effect of nonlinear air damping of the resonator. It was also found that the increment of pressure drop by the presence of resonator arrays was about 9 % at flow speed of 25 m/s.

선박용 소음기 성능 시험 및 평가

김봉기(Kim, Bong-Ki),김상렬(Kim, Sang-Ryul),김현실(Kim, Hyun-Sil),신민철(Shin, Min-Chol) 한국소음진동공학회 2008 한국소음진동공학회 논문집 Vol.18 No.12

A muffler design in the exhaust system is critical to provide fur low noise in shipboard spaces. In an attempt to effectively design the low noise muffler, it Is important to evaluate the performance of the muffler considering not only the noise, but also pressure drop as well. For this purpose, a test system of large exhaust mufflers fur ship propulsion systems was designed based on ISO 7235. The substitution test fur determining both the insertion loss and pressure drop of mufflers was carried out. A ship exhaust muffler is considered as a test example and the insertion loss and pressure drop were obtained.

삽입재 크기에 따른 코니컬 커터의 현장내구성 평가 연구

최순욱 사단법인 한국터널지하공간학회 2019 한국터널지하공간학회논문집 Vol.21 No.1

본 연구는 로터리드럼커터에 적용된 두 종류의 코니컬 픽커터에 대한 현장시험을 통해시험 전과 후의 육안조사와 중량감소 및 마모부피를 측정하여 코니컬 픽커터의 내구성을 비교 ‧ 분석하였다. 육안조사를 통해 슬림 타입 코니컬 픽커터에서만 총 9개의 삽입재손실이 나타남을 확인하였고 삽입재 보호를 위해 두부의 두께가 중요함을 알 수 있었다. 시험 전과 후의 픽커터의 중량손실과 마모부피는 헤비타입이 슬림타입에 비해 반이하로 작게 나타나 경암반에서 헤비타입이 더 유용함을 확인할 수 있었다. 픽커터의 마모손실을 판단할 때, 중량측정과 마모부피 측정결과의 상호 비교는 재료의 단위중량과 굴착에 의한 스폴링에 의해 차이가 나타날 수 있으므로 주의해야 할 것으로 판단된다 In this study, the durability of conical pick cutter was compared and analyzed by preand post-test visual inspection, measurement of weight loss and wear volume through field test on two types of conical pick cutters applied to rotary drum cutter. In the visual inspection, it was found that only 9 inserts were lost in the slim type conical pick cutter. This result show that the thickness of the head cover surrounding a insert was important to maintain the insert during excavation. The weight loss and wear volume of the heavy type conical pick cutter were less than half that of the slim type. From these results, it can be confirmed that heavy type is more useful than slim type in hard rock. It should be noted that, when determining the wear loss of the conical pick cutter, the mutual comparison of the weight measurement and the wear volume measurement results may be different due to the unit weight of the material and the spalling caused by excavation.

방음 루버의 음향효과 예측에 관한 연구

김태민(Tae-Min Kim),김정태(Jeung-Tae Kim),김다래(Da-Rae Kim),고효인(Hyo-In Koh),손정곤(Jeung-gon Son) 한국소음진동공학회 2015 한국소음진동공학회 학술대회논문집 Vol.2015 No.4

In order to reduce damage of noise in residential area around railroad, it is established such as soundproof walls or soundproof tunnel. In a case of soundproof facilities established on bridge, it is needed to a lot of cost due to safety factor, also it is demanded weight-lightening design of soundproof facilities to be able to reduce reinforcement cost. This study is configured on a method of reducing soundproof facilities weight-lightening and wind load caused by external flow. Absorptive acoustic louver which is a type of silencer is concerned to reduce the weight of soundproof facilities and is measured using small reverberation chamber so that application of acoustic louver is confirmed to soundproof facilities. Insertion loss(IL) of acoustic louver is on the rise in particular frequency, whereas it is nearly constant except for that frequency. Therefore, acoustic louver is appropriated for soundproof tunnel. In further study, effect on environment noise with soundproof facilities applied by acoustic louver will be examined through numerical analysis in reality model.

공명형 방음벽 상단장치의 음향성능 평가 방안

윤제원,조용성,장강석,김영찬 한국생태환경건축학회 2017 한국생태환경건축학회 논문집 Vol.17 No.6

Purpose : The purpose of this study is to investigate the acoustic performance evaluation method for resonance type noise reduction device installed on the top of noise barrier. Method: In order to evaluate the acoustic performance of the resonance type noise reduction device installed on the top of noise barrier, the measurement of insertion loss in the semi-anechoic chamber and transmission loss using the impedance tube were conducted. Acoustic mode analysis was also performed to evaluate the resonance frequency of a complicated shaped resonator. By using the two-dimensional boundary element method, the study on the deriving a problem in evaluating the acoustic performance at the rear stage of the resonance type device was conducted and an alternative solution of the problem was suggested, and the acoustic performance in the rear stage of resonance type device was evaluated when a number of resonators were mixed. Result : In order to solve the difficulty in analysis of the acoustic characteristics of resonance type noise reduction device, an effective evaluation method was proposed by using the two-dimensional boundary element method in present work. Also acoustic performance was analyzed at the receiver point of the noise reduction device in which many resonators present simultaneously.