연료전지 자동차용 흡기 소음기의 설계 변수 최적화에 관한 연구

김의열(Eui-Youl Kim),김민수(Min-Soo Kim),이상권(Sang-Kwon Lee),서상훈(Sang-Hoon Seo) 한국소음진동공학회 2009 한국소음진동공학회 학술대회논문집 Vol.2009 No.4

프린터 음질평가를 위한 순음도 설계

김의열(Kim, Eui-Youl),이영준(Lee, Young-Jun),이상권(Lee, Sang-Kwon) 한국소음진동공학회 2012 한국소음진동공학회 논문집 Vol.22 No.4

The operating sound radiated from a laser printer includes tonal noise components caused by the rotating mechanical parts such as gear, shaft, motor, fan, etc. The negative effects of the tonal noise components need to be considered in the process of developing a sound quality index for the quantitative evaluation of the emotional satisfaction in terms of psycho-acoustics. However, in a previous paper, it was confirmed that the Aures tonality did not have enough correlation with the results of jury evaluation. The sound quality index based on loudness, articulation index, fluctuation strength has a little problem in considering the effects of rotating mechanical parts on the sound quality. In this paper, to solve the tonality evaluation problem, the calculation algorithm of Aures tonality was investigated in detail to find the cause of decreasing the correlation. The new tonality evaluation model was proposed by modifying and optimizing the masking effect, loudness ratio, and shape of weighting curve based on the basic algorithm of Aures tonality, and applied to two kinds of operating sound groups in order to verify the usefulness of proposed model. As a result, it is confirmed that the proposed tonality evaluation model has enough correlation and usefulness for expressing the tonalness in the operating sounds of laser printers. In the following paper, this results will be used to model the sound quality index as the input data by using the classification algorithm.

흡기계 능동소음제어를 위한 적응형 필터 알고리즘의 개발

김의열(Kim, Eui-Youl),김병현(Kim, Byung-Hyun),김호욱(Kim, Ho-Wuk),이상권(Lee, Sang-Kwon) 한국소음진동공학회 2012 한국소음진동공학회 논문집 Vol.22 No.2

The filtered-x LMS(FX-LMS) algorithm has been applied to the active noise control(ANC) system in an acoustic duct. This algorithm is designed based on the FIR(finite impulse response) filter, but it has a slow convergence problem because of a large number of zero coefficients. In order to improve the convergence performance, the step size of the LMS algorithm was modified from fixed to variable. However, this algorithm is still not suitable for the ANC system of a short acoustic duct since the reference signal is affected by the backward acoustic wave propagated from a secondary source. Therefore, the recursive filtered-u LMS algorithm(FU-LMS) based on infinite impulse response(IIR) is developed by considering the backward acoustic propagation. This algorithm, unfortunately, generally has a stability problem. The stability problem was improved by using an error smoothing filter. In this paper, the recursive LMS algorithm with variable step size and smoothing error filter is designed. This recursive LMS algorithm, called FU-VSSLMS algorithm, uses an IIR filter. With fast convergence and good stability, this algorithm is suitable for the ANC system in a short acoustic duct such as the intake system of an automotive. This algorithm is applied to the ANC system of a short acoustic duct. The disturbance signals used as primary noise source are a sinusoidal signal embedded in white noise and the chirp signal of which the instantaneous frequency is variable. Test results demonstrate that the FU-VSSLMS algorithm has superior convergence performance to the FX-LMS algorithm and FX-LMS algorithm. It is successfully applied to the ANC system in a short duct.

승합차량의 액슬기어 음질의 평가를 위한 새로운 순음도 모델 개발과 응용

김의열(Kim, Eui-Youl),장지욱(Jang, Ji-Uk),이상권(Lee, Sang-Kwon) 한국소음진동공학회 2012 한국소음진동공학회 논문집 Vol.22 No.12

Aure's tonality was considered as the sound metrics for the expression of the tonality of gear whine sound in a previous research. It was failed to use the Aure's tonality as a sound metric for the tonal impression. Thus Aures's tonality, was developed for tonal impression in previous research. However, this metric did not express well the tonality of gear whine sound since the whine sound is a non-stationary signal with frequency modulation and amplitude modulation. In this study, the new method for the tonality evaluation for a non-stationary signal is presented. It is developed based on the prominence ratio, tonality impression function, and lower threshold level. It improves the accuracy and reliability of the sound quality index being used for the sound quality evaluation of the axle-gear whine sound.

유전자 알고리즘을 이용한 타이어 공력소음의 저감

김의열(Kim, Eui-Youl),황성욱(Hwang, Sung-Wook),김병현(Kim, Byung-Hyun),이상권(Lee, Sang-Kwon) 한국소음진동공학회 2012 한국소음진동공학회 논문집 Vol.22 No.1

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.

연료전지 자동차용 흡기 소음기의 설계 변수 최적화에 관한 연구

김의열(Kim, Eui-Youl),이상권(Lee, Sang-Kwon) 한국소음진동공학회 2009 한국소음진동공학회 논문집 Vol.19 No.7

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.

흡기계 능동소음제어를 위한 적응형 필터 알고리즘의 개발

김의열(Eui-Youl Kim),김호욱(Ho-Wuk Kim),이상권(Sang-Kwon Lee) 한국소음진동공학회 2009 한국소음진동공학회 학술대회논문집 Vol.2009 No.11

LCD 라인의 음향 특성신호에 웨이브렛 변환과 인경신경망회로를 적용한 공정로봇의 건정성 감시 연구

김의열(Eui-Youl Kim),이상권(Sang-kwon Lee),장지욱(Ji-Uk Jang) 대한기계학회 2012 大韓機械學會論文集A Vol.36 No.7

LCD 생산라인의 공정 로봇에서 방사되는 비정상 작동 소음은 로봇의 결함 탐지에 사용된다. 이신호의 장점은 상대적으로 낮은 민감도에 비해 단지 마이크로폰을 이용하여 다수의 결함을 확인할 수 있는 것이다. 결함요소 추출을 위한 웨이브렛 변환(WPT)과 불량의 분류를 위한 인공신경망 회로(ANN) 이 본 논문에서 사용되었다. 결과적으로, 비정상 작동 소음이 기계요소의 결함 진단에 효율적으로 사용될 수 있다. Abnormal operating sounds radiated from a moving transfer robot in LCD (liquid crystal display) product lines have been used for the fault detection line of a robot instead of other source signals such as vibrations, acoustic emissions, and electrical signals. Its advantage as a source signal makes it possible to monitor the status of multiple faults by using only a microphone, despite a relatively low sensitivity. The wavelet packet transform for feature extraction and the artificial neural network for fault classification are employed. It can be observed that the abnormal operating sound is sufficiently useful as a source signal for the fault diagnosis of mechanical components as well as other source signals.

연속웨이브렛 변환을 이용한 충격음 위치 규명

김의열(Eui Youl Kim),김민수(Min Su Kim),이상권(Sang Kwon Lee),고재필(Jae Pil Koh) 대한기계학회 2010 大韓機械學會論文集A Vol.34 No.11

본 연구에서는 지하에 매설된 가스 파이프에 가해진 충격의 위치를 탐지하기 위한 개선된 방법을 제시하고 있다. 가스 파이프에서 가스 누출은 건설 기계 장비에 의한 기계적 충격에 의해 발생하며, 가스 이송 산업계에 치명적인 재해을 발생시킬 수 있다. 이와 같은 문제를 초기에 발견하고 조치를 취하기 위해 기존에는 충격 위치 탐지를 위해 상관 관계 기법이 사용되어 왔다. 하지만, 외부 충격에 의해 파이프 따라 전파되는 음향파의 분산 특성은 양쪽 센서에 측정되는 도착 시간을 사용하여 센서 사이에 도착 시간 지연을 예측하는데 상당한 에러를 발생 시킬 수 있다. 그래서 이 논문에서는 분산파 대신 직접파의 도착 시간 지연을 측정하기 위해 웨이블렛 기법을 사용하였다. 제안된 방법은 지하에 매설된 실제 가스 파이프에서 측정된 음향 신호에 적용하여 기존의 상관 관계 기법에 비해 외부 충격 위치를 추정하는데 보다 효과적임을 확인하였다. This paper presents a new method for indentifying the location of impact source in a buried duct. In a gas pipeline, the problem of leakage occurs due to the mechanical load exerted by construction equipment. Such leakage can cause catastrophic disasters in gas supply industries. Generally, the cross-correlation method has been used for indentifying the location of impact source in a pipeline. Since this method involves the use of the dispersive acoustic wave, it derives an amount of error in process of estimating the time delay between acoustic sensors. The object of this paper is to estimate the time delay in the arrival of the direct wave by using the wavelet transform instead of the dispersive wave. The wavelet transform based method gives more accurate estimates of the impact location than the cross-correlation method does. This method is successfully used to identify the location of impact force in an actual buried gas duct.

프린터의 음질 인덱스 제작과 음질개선에 대한 응용

김의열(Kim, Eui-Youl),이영준(Lee, Young-Jun),이상권(Lee, Sang-Kwon) 한국소음진동공학회 2012 한국소음진동공학회 논문집 Vol.22 No.6

The sound quality based on design optimization, throughout the development process of various electronic office equipments, needs to be considered in order to respond the increased needs for the emotional satisfaction of customers in terms of psycho-acoustics. This paper focuses on how to describe the characteristics of operating sound radiated from laser printers by using various sound attributes, and to model the sound quality index that can properly evaluate the subjective preference on modification conditions in the improvement study quantitatively. Especially, the proposed verification process, in the form of combining the correlation based method and the decision error based method, was applied to improve the generality and reliability of a group of participants in the jury evaluation. The modified Aures tonality model was also proposed to improve the correlation coefficient with the mean response of participants by optimizing some parameters. As a result, the loudness, articulation index, roughness, tonality, fluctuation strength were used to model the sound quality index for laser printers by using the multiple-linear regression method. Through the improvement study, it was confirmed that replacing the absorbing materials is effective to reduce the tonalness radiated from the side of a reference printer model. Based on above results, it can be concluded that the proposed model has enough usefulness as quantitative evaluation index to evaluate the difference between modification conditions in the improvement study.