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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.
나공태(Kongtae Ra),김경태(Kyung-Tae Kim),김종근(Joung-Keun Kim),김은수(Eun-Soo Kim),이정무(Jung-Moo Lee),김의열(Eu-Yeol Kim),이승용(Sung-Yong Lee),김성근(Sung-Keun Kim),박은주(Eun-Ju Park) 한국해양환경·에너지학회 2013 한국해양환경공학회 학술대회논문집 Vol.2013 No.11
본 연구에서는 시화호 유역에 존재하는 비점오염물질의 유출특성 및 총부하량에 대하여 조사하였다. 연구지역은 도심을 대표하는 안산천, 화정천, 산업단지를 대표하는 반월스마트허브 3토구 및 인위적인 오염이 없는 남측간석지를 대상으로 하였으며 강우시 강우유출수를 채취하였다. 반월스마트허브 3토구에서의 비점오염물질의 평균농도는 SS 235.7 mg/L, COD 45.8 mg/L, DIP 3.907 mg/L, DIN 31.225 mg/L, TP 9.648 mg/L, TN 58.832 mg/L로 다른 조사지역에 비해 모든 비점오염물질의 평균농도가 높았다. 남측간석지에서 DIP, DIN, TP, TN 등이 가장 낮은 농도를 보이고 있었다. 강우지속시간동안의 누적오염부하량은 안산천에서 SS 15,113 Kg, COD 1,183 Kg, TP 35.8 Kg, TN 358.8 Kg으로 다른 조사지역에 비해 상대적으로 높았으며 유량에 큰 영향을 받고 있었다. Non-point pollutants including SS, COD, nutrients, TN, TP in the stormwater runoffs around Shihwa Lake have been investigated to study their concentration and total loads at 4 different sites. Mean concentration of SS, COD, DIP, DIN, TP and TP were 235.7, 45.8, 3.907, 31.225, 9.648, 58.832 mg/L, respectively. The non-point pollutants such as DIP, DIN, TP and TN exhibited the lowest values relative to the Ansan and Hwajeong streams and Banweol 3<SUP>rd</SUP> sewer outlet. The average of total runoff fluxes for SS, COD, TP and TN in the present study were 15,113 kg, 1,183 kg, 35.8 kg and 358.8 kg, respectively. Enormous amount of non-point pollutants was entered into Shihwa Lake without any treatment.
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.
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.
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.
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.
프린터 음질평가의 신뢰성을 위한 결정오차 모델설계 및 실험적 검증
김의열(Kim, Eui-Youl),이영준(Lee, Young-Jun),이상권(Lee, Sang-Kwon) 한국소음진동공학회 2012 한국소음진동공학회 논문집 Vol.22 No.7
In this study, the possibility of decision error is investigated to identify and improve the reliability of participants in the process of conducting the sound quality analysis for laser printers. So far, there is not a way to identify and express the possibility of individual participant quantitatively. Thus, the decision error model is proposed which is based on the expectation value between the perceived sounds. Through the experimental verification on the laser printers, it was found that the possibility of decision error is affected according to the normalized difference. The possibility of decision error has inversely proportional to the normalized difference between the perceived sounds. When the normalized difference becomes small value, the uncertainly between decisions is inversely increase, and then it is difficult to obtain the proper result in the process of the jury evaluation for laser printers. For this reason, in this study, the proposed decision error model is added in the previous step of the correlation verification. Comparing to the conventional process only using the correlation based method, after the reliability of each participant is verified, the correlation with the mean response of participants is verified. It was found that the participants who were recognized as having unusual preferences are actually identified as having the reliability problem. Based on the results of this study, the proposed decision error model will be helpful to identify and improve the reliability of participants in the following study for the sound quality analysis.