A Malfunction Pattern Distinction of an Automotive Electric part by Sound and Vibration Frequency Analysis

Han-Sub Sim(심한섭) 한국기계가공학회 2021 한국기계가공학회지 Vol.20 No.12

The usage of electric-powered components consisting of several electrical and mechanical parts is continuously increasing in automobiles. Therefore, continuous assessment of the reliability and quality of these electric-powered parts is crucial. In this study, a noise and vibration measurement system for testing and evaluating the different electric-powered parts of automobiles was designed. Further, an FFT analysis was performed on some electric-powered steering assembly test equipment. In the FFT analysis of the noise and vibration signals for each essential fault part, the vibration FFT analysis was significantly compared with the noise analysis. The results showed that the vibration FFT analysis was more effective in determining the reliability and quality of the electric-powered parts.

고속도로 톨게이트 근처 럼블스트립 형태에 따른 진동 데시벨 연구

김도완,장영선,문성호 한국도로학회 2013 한국도로학회논문집 Vol.15 No.6

PURPOSES: The rumble strip installed at the highway near the tollgate has the purpose to reduce the vehicle velocity or prevent sleepiness by awakening people to the danger. These rumble strip has different vibration decibel from the rumble strip shapes, resulting in some fatigue damage to human because a driver suffers from a lot of stress and displeasure. In this connection, the objective of this paper is to analyze the vibration decibel perceived by a driver in the vehicle under some conditions. METHODS: The vibration decibel conveyed from the tire can be analyzed. The frequency analysis methods were used according to DFT (Discrete Fourier Transform) analysis, FFT (Fast Fourier Transform) analysis, CPB (Constant Percentage Bandwidth) analysis. But the frequency analysis method in this paper is the 1/24 OCT(Octave) band analysis because of the convenience of the analysis and the overall vibration amplitude along the frequency. RESULTS : By using the results of the vibration decibel after analyzing the 1/24 OCT band analysis, these results can be compared from some conditions (e.g., rumble strip shape, uniform velocity of a vehicle, road condition, mass of a vehicle). As a result, the numerical values of decibel are not directly proportional to the vehicle velocity. CONCLUSIONS : At the condition that a vehicle is passing by the rumble strip, the value of a vibration decibel at the rumble strip of the cylinder shape is smaller than the rumble strip of rectangular shape regardless of the rumble strip depth and width. At the mass condition, the more a vehicle is massive, the more the vibration decibel increases. At the road condition, the vibration decibel at the wet road is smaller than the value at dry road condition.

고속도로 톨게이트 근처 럼블스트립 형태에 따른 진동 데시벨 연구

김도완,장영선,문성호 한국도로학회 2013 한국도로학회논문집 Vol.15 No.6

PURPOSES: The rumble strip installed at the highway near the tollgate has the purpose to reduce the vehicle velocity or prevent sleepiness by awakening people to the danger. These rumble strip has different vibration decibel from the rumble strip shapes, resulting in some fatigue damage to human because a driver suffers from a lot of stress and displeasure. In this connection, the objective of this paper is to analyze the vibration decibel perceived by a driver in the vehicle under some conditions. METHODS: The vibration decibel conveyed from the tire can be analyzed. The frequency analysis methods were used according to DFT (Discrete Fourier Transform) analysis, FFT (Fast Fourier Transform) analysis, CPB (Constant Percentage Bandwidth) analysis. But the frequency analysis method in this paper is the 1/24 OCT(Octave) band analysis because of the convenience of the analysis and the overall vibration amplitude along the frequency. RESULTS : By using the results of the vibration decibel after analyzing the 1/24 OCT band analysis, these results can be compared from some conditions (e.g., rumble strip shape, uniform velocity of a vehicle, road condition, mass of a vehicle). As a result, the numerical values of decibel are not directly proportional to the vehicle velocity. CONCLUSIONS : At the condition that a vehicle is passing by the rumble strip, the value of a vibration decibel at the rumble strip of the cylinder shape is smaller than the rumble strip of rectangular shape regardless of the rumble strip depth and width. At the mass condition, the more a vehicle is massive, the more the vibration decibel increases. At the road condition, the vibration decibel at the wet road is smaller than the value at dry road condition.

수치적 방법을 이용한 3차원 거친 표면의 마모 해석

김윤지,서준호,김봉준,유용훈 한국트라이볼로지학회 2020 한국윤활학회지(윤활학회지) Vol.36 No.4

It is essential to predict the amount of wear and surface parameters for a surface where relative motion occurs. In the asperity-based model for wear prediction, only the average contact pressure can be obtained. Hence, the accuracy of wear analysis is poor. In this study, DC-FFT is used to obtain the pressure of each node, and wear analysis is performed by considering the effect of the pressure gradient. The numerical surface generation method is used to create Gaussian, negatively skewed, and positively skewed surfaces for wear analysis. The spatial and height distributions of each surface are analyzed to confirm the effectiveness of the generated surface. Furthermore, wear analysis is performed using DC-FFT and Archard's wear formula. After analysis, it is confirmed that all peaks are removed and only valleys remain on the surface. The RMS roughness and Sk continue to decrease and Ku increases as the cycle progresses. It is observed that the surface parameters are significantly affected by the radius of curvature of the asperity. This analysis method is more accurate than the existing average wear and truncation models because the change in asperity shape during the wear process is reflected in detail.

Pass-by계측과 NCPX계측에 의한 주파수 별 음압 예측 모델개발에 관한 연구

김도완,문성호,안덕순,손현장 한국도로학회 2013 한국도로학회논문집 Vol.15 No.6

PURPOSES: The methods of measuring the sound from the noise source are Pass-by method and NCPX (Noble Close Proximity) method. These measuring methods were used to determine the linkage of TAPL (Total Acoustic Pressure Level) and SPL (Sound Pressure Level) in terms of frequencies. METHODS : The frequency analysis methods are DFT (Discrete Fourier Transform) and FFT (Fast Fourier Transform), CPB (Constant Percentage Bandwidth). The CPB analysis was used in this study, based on the 1/3 octave band option configured for the frequency analysis. Furthermore, the regression analysis was used at the condition related to the sound attenuation effect. The MPE (Mean Percentage Error) and RMSE (Root Mean Squared Error) were utilized for calculating the error. RESULTS: From the results of the CPB frequency analysis, the predicted SPL along the frequency has 99.1% maximum precision with the measured SPL, resulting in roughly 1 dB(A) error. The TAPL results have precision by 99.37% with the measured TAPL. The predicted TAPL results at this study by using the SPL prediction model along the frequency have the maximum precision of 98.37% with the vehicle velocity. CONCLUSIONS: The Predicted SPL model along the frequency and the TAPL result by using the predicted SPL model have a high level of accuracy through this study. But the vehicle velocity-TAPL prediction model from the previous study by using the log regression analysis cannot be consistent with the TAPL result by using the predicted SPL model.

Pass-by계측과 NCPX계측에 의한 주파수 별 음압 예측 모델 개발에 관한 연구

김도완,문성호,안덕순,손현장 한국도로학회 2013 한국도로학회논문집 Vol.15 No.6

PURPOSES: The methods of measuring the sound from the noise source are Pass-by method and NCPX (Noble Close Proximity) method. These measuring methods were used to determine the linkage of TAPL (Total Acoustic Pressure Level) and SPL (Sound Pressure Level) in terms of frequencies. METHODS : The frequency analysis methods are DFT (Discrete Fourier Transform) and FFT (Fast Fourier Transform), CPB (Constant Percentage Bandwidth). The CPB analysis was used in this study, based on the 1/3 octave band option configured for the frequency analysis. Furthermore, the regression analysis was used at the condition related to the sound attenuation effect. The MPE (Mean Percentage Error) and RMSE (Root Mean Squared Error) were utilized for calculating the error. RESULTS: From the results of the CPB frequency analysis, the predicted SPL along the frequency has 99.1% maximum precision with the measured SPL, resulting in roughly 1 dB(A) error. The TAPL results have precision by 99.37% with the measured TAPL. The predicted TAPL results at this study by using the SPL prediction model along the frequency have the maximum precision of 98.37% with the vehicle velocity. CONCLUSIONS: The Predicted SPL model along the frequency and the TAPL result by using the predicted SPL model have a high level of accuracy through this study. But the vehicle velocity-TAPL prediction model from the previous study by using the log regression analysis cannot be consistent with the TAPL result by using the predicted SPL model.

Cu박판의 초음파 금속 용착 실험을 통한 용착성 평가

박우열(Woo Yeol Park),장호수(Ho Su Jang),김정호(Jung Ho Kim),박동삼(Dong Sam Park) 한국생산제조학회 2012 한국생산제조학회지 Vol.21 No.4

The Ultrasonic metal welding is used in the solid-phase welding method at room temperature or low temperature state. In welding process, the high frequency vibration energy is delivered to the welding part under the constant pressure for welding. In this study, we aimed to design and manufacture a 40,000 Hz band horn through finite element analysis. By performing modal analysis and harmonic response analysis, the modal analysis result is that the horn frequency was 39,599Hz and the harmonic response result that the horn frequency was 39,533Hz. These results were similar. In order to observe the designed horns performance, about 4,000 voltage data was obtained from a light sensor and was analyzed by FFT analysis using Origin Tool. The result RMS amplitude was approximately 8.5㎛ at 40,000Hz, and maximum amplitude was 12.3㎛. Using this manufactured horn along with an ultrasonic metal welder and tension tester, the weldability of Cu sheets was evaluated. The maximum tensile force was 66.53 N in the welding condition of 2.0 bar pressure, 60% amplitude, and 0.32s welding time. In excessive welding conditions, it was revealed that weldability is influenced negatively.

확장형 칼만필터 알고리즘을 활용한 차량 주행에 따른 마찰소음의 총 음압레벨 예측

김도완,한범수,문성호,안덕순 한국도로학회 2014 한국도로학회논문집 Vol.16 No.5

PURPOSES: This study is to predict the Sound Pressure Level(SPL) obtained from the Noble Close ProXimity(NCPX) method by using theExtended Kalman Filter Algorithm employing the taylor series and Linear Regression Analysis based on the least square method. The objectiveof utilizing EKF Algorithm is to consider stochastically the effect of error because the Regression analysis is not the method for the staticalapproach. METHODS: For measuring the friction noise between the surface and vehicle’s tire, NCPX method was used. With NCPX method, SPL canbe obtained using the frequency analysis such as Discrete Fourier Transform(DFT), Fast Fourier Transform(FFT) and Constant PercentageBandwidth(CPB) Analysis. In this research, CPB analysis was only conducted for deriving A-weighted SPL from the sound power level interms of frequencies. EKF Algorithm and Regression analysis were performed for estimating the SPL regarding the vehicle velocities. RESULTS : The study has shown that the results related to the coefficient of determination and RMSE from EKF Algorithm have beenimproved by comparing to Regression analysis. CONCLUSIONS : The more the vehicle is fast, the more the SPL must be high. But in the results of EKF Algorithm, SPLs are irregular. The reason of that is the EKF algorithm can be reflected by the error covariance from the measurements.

확장형 칼만필터 알고리즘을 활용한 차량 주행에 따른 마찰소음의 총 음압레벨 예측

김도완,한범수,문성호,안덕순 한국도로학회 2014 한국도로학회논문집 Vol.16 No.5

PURPOSES: This study is to predict the Sound Pressure Level(SPL) obtained from the Noble Close ProXimity(NCPX) method by using the Extended Kalman Filter Algorithm employing the taylor series and Linear Regression Analysis based on the least square method. The objective of utilizing EKF Algorithm is to consider stochastically the effect of error because the Regression analysis is not the method for the statical approach. METHODS: For measuring the friction noise between the surface and vehicle’s tire, NCPX method was used. With NCPX method, SPL can be obtained using the frequency analysis such as Discrete Fourier Transform(DFT), Fast Fourier Transform(FFT) and Constant Percentage Bandwidth(CPB) Analysis. In this research, CPB analysis was only conducted for deriving A-weighted SPL from the sound power level in terms of frequencies. EKF Algorithm and Regression analysis were performed for estimating the SPL regarding the vehicle velocities. RESULTS : The study has shown that the results related to the coefficient of determination and RMSE from EKF Algorithm have been improved by comparing to Regression analysis. CONCLUSIONS : The more the vehicle is fast, the more the SPL must be high. But in the results of EKF Algorithm, SPLs are irregular. The reason of that is the EKF algorithm can be reflected by the error covariance from the measurements.

시간-에너지 분석을 이용한 전기설비 이상신호 검출

池昇昱(S. W. Jee),李春夏(C. H. Lee),金忠年(Ch. N. Kim),李廣植(K. S. Lee),沈光烈(K. Y. Sim) 대한전기학회 2006 전기학회논문지C Vol.55 No.2

Most of electric accidents are happened in the place where activities are frequent by common people who has low electric knowledge. Also, accidents are increased in the low voltage electric equipment. So, it is increased to spread the dispersion or non-utility power generation system. It means that ordinary times observation is required for electric equipments by common people. This paper is studied for the diagnosis method of electric equipment that common people can diagnose easily. Voltage is generally and exactly measured in the electric and electronic field. We suggest new analysis tools using only electric voltage. It is called the Time-Energy analysis. The Time-Energy analysis is as following First, divide measured voltage waves into same parts, Second, conducted FFT(Fast Fourier Transform) transform for each divided period, Finally, each results are reassembled after graphic treatment. We compared Time-Energy analysis with discharge form by tracking tester. As the result, tracking discharge processes distinguished clearly.