Soon Woo Han - Independent Researcher (original) (raw)
Papers by Soon Woo Han
압축센싱을 적용한 회전체 시스템의 통계학적 상태진단
Condition Monitoring(CM) methods encounter a big data problem in processing the data collected th... more Condition Monitoring(CM) methods encounter a big data problem in processing the data collected through dense sensor networks with a high sampling rate. For this reason, compressive sensing technique has been introduced to improve efficiency and scalability of today"s CM procedures parallel to data acquisition improvement. In this study, Compressive sensing approach for condition monitoring is proposed to demonstrate efficiency in handling a large amount of data. For experiments, a built-in system was used for condition monitoring of a rotating system. During the experiments, all data were sampled with compressive sensing to obtain compressed data. Then we had performed condition monitoring only using compressed data without the reconstruction process. Experimental results show that the proposed method could effectively improve the speed of data processing and reduce energy consumption of sensing networks.
Transactions of the Korean Society for Noise and Vibration Engineering, 2006
Transactions of the Korean Society of Mechanical Engineers A, 2011
Transactions of the Korean Society for Noise and Vibration Engineering, 2015
In recent years, pattern recognition methods have been widely used by many researchers for fault ... more In recent years, pattern recognition methods have been widely used by many researchers for fault diagnoses of mechanical systems. The soundness of a mechanical system can be checked by analyzing the variation of the system vibration characteristic along with a pattern recognition method. Recently, the hidden Markov model has been widely used as a pattern recognition method in various fields. In this paper, the hidden Markov model is employed for the fault diagnosis of the mass un
Apparatus and method for generating and sensing torsional vibrations using magnetostriction
구동중인 자동차 배기계의 진동 특성 측정
Transactions of the Korean Society for Noise and Vibration Engineering, 2007
In this work, the operational deflection shape(ODS) of an automobile exhaust system is measured b... more In this work, the operational deflection shape(ODS) of an automobile exhaust system is measured by using a recently-developed magnetic sensor. The magnetic sensor is composed of a solenoid and two pairs of permanent magnets generating an antisymmetric magnetic field in the lateral direction inside the solenoid. Lateral movement of a ferromagnetic pipe inside the magnetic field of the suggested sensor induces an electromotive force in the solenoid corresponding to the lateral velocity of the pipe. Due to the simplicity and non-contact characteristics of the magnetic sensor, dynamic behaviors of the structures operating under high temperature such as an exhaust pipe can be efficiently observed. It is shown that the lateral ODS of an exhaust system can be successfully measured by the suggested sensors.
Improvement of Ride Comfort of the Excavator
SAE Technical Paper Series, 1997
Transactions of the Korean Society for Noise and Vibration Engineering, 2008
This paper suggests a non-contact sensor for measuring bending vibration of a non-metallic cylind... more This paper suggests a non-contact sensor for measuring bending vibration of a non-metallic cylinder in two orthogonal directions simultaneously. Recent research shows that a solenoid can pick up bending vibrations of a nonmetallic cylinder based on the reversed Lorentz force mechanism if an electrical conductive patch is attached to the cylinder. In this work, pairs of specially designed patches are used to make two independent paths for the current induced by bending vibrations, which enables the measurement of bending vibrations along two orthogonal directions simultaneously. The working performance of the developed sensor was verified by using two accelerometers.
Transactions of the Korean Society of Mechanical Engineers A, 2012
Wavelet-Based Wavenumber Filtering for Damage Detection and Thickness Estimation with Laser-Scanning
Structural Health Monitoring 2017
This paper presents the use of wavelet-based wavenumber filtering for damage detection and thickn... more This paper presents the use of wavelet-based wavenumber filtering for damage detection and thickness estimation with Laser-scanning sensing. A piezoelectric transducer provides an excitation at a fixed, single frequency to a structure. Laser Doppler Vibrometer (LDV) with a mirror-tilting device measures subsequent steadystate structural responses, resulting in the full standing wavefield of the structure at the excitation frequency. After then, wavelet-based wavenumber filtering is performed to obtain dominant wavenumber components, which could be used for indicative of structural damage. Mapping processes based on the dominant wavelet-based wavenumber is carried out for damaged area visualization. To estimate the depth of damages, Lamb wave equation is transformed into the wavenumber-thickness equation with the known structural parameters. With this process, the thickness and the thickness reduction by corrosion was accurately identified. Several experiments are performed on thin walled structures, including pipes and plates, with different types of damage, including corrosion and cracks. The experimental investigation into quantitative assessment of welded joints are also performed. The results show that the techniques are very effective in damage size and depth estimation with improved speed.
Measurement of Thickness of Wall-Thinned Plate using Acoustic Wavenumber Spectroscopy and Spatial Local Wavenumber Filtering
Structural Health Monitoring-an International Journal, 2017
The surface of a structure can generate cracks or wall-thinning, due to corrosion. This can event... more The surface of a structure can generate cracks or wall-thinning, due to corrosion. This can eventually lead to the fracture of the structure, which can trigger enormous fatality and property loss. Thereby, a laser imaging technology on such structures as thin plate structure, or piping which thickness is relatively thin in comparison to the area, has been steadily studied for the past 10 years. The most typical among the laser imaging technology is the pulse laser imaging. By using the same, a new technology for inspecting and imaging a desired area within a relatively short period of time was developed, so as to scan various structures including the thin-plate structure and piping. However, this method builds images by measuring waves reflected from defects, and have a time delay of a few milliseconds at each scanning point. Moreover, complexity of the systems is so high due to additional components such as laser focusing parts. This paper proposes laser imaging method with increas...
This paper describes the comparison study of wavenumber-based damage detection performance in ful... more This paper describes the comparison study of wavenumber-based damage detection performance in full field laser scanning techniques. Two types of excitation methods (guided waves and standing waves) are used for damage detection. For the standing wave based technique, the steady-state response could be obtained from a Laser Doppler Vibrometer and a mirror tilting device using a single fixed frequency (>50 kHz) from a mounted piezoelectric transducer. Time variant and invariant feature based damage visualization method is used to estimate damage size and depth. For the guided wave based approach, the same procedure is used except that a piezo actuator generates a tone-burst excitation. For the comparison of these two techniques, several experiments are performed on an aluminium plates and a composite plate which contain various types of damage, including corrosion and crack on an aluminium plate and debonding on a composite plate. The results demonstrate that pros and cons of these...
An Integrated Ultrasonic Imaging Technique using Laser Scanning System
Structural Health Monitoring-an International Journal, 2019
This paper presents an integrated methodology to improve the performance of laserscanning based d... more This paper presents an integrated methodology to improve the performance of laserscanning based damage detection for large structures with various obstacles. Two different ultrasonic imaging schemes are integrated in this technique, which involves the use of beamforming imaging with local scanning, along with standing wave based full field laser scanning. Two types of excitation methods (guided waves and standing waves) are used for damage detection. The wave field measurements are obtained from a Laser Doppler Vibrometer and a mirror tilting device using a single fixed frequency (>80 kHz) excitation from a mounted piezoelectric transducer. First, a newly developed beamforming imaging technique with frequency-wavenumber filtering using local guided wave measurement is performed to identify the presence and location of damage in large structures without full field measurements. Once the damage is identified, the steady-state response based full field laser scanning is used to quan...
Transactions of the Korean Society for Noise and Vibration Engineering
Multi Frequency Standing Wave Ultrasonic Imaging based Full-Field Laser Scanning
JOURNAL OF THE KOREAN SOCIETY FOR NONDESTRUCTIVE TESTING
Analysis of Bending Wave Propagation Behavior by Impact Loading in Plate Structure Using Finite Element Method
JOURNAL OF THE KOREAN SOCIETY FOR NONDESTRUCTIVE TESTING
Generation and Detection of Torsional Waves in a Rotating Shaft Using a Magnetostrictive Patch Array
Transactions of the Korean Society of Mechanical Engineers A
ABSTRACT
Crack Visualization Using Laser-scanning based Guided Ultrasonic and Standing Waves Response Image
JOURNAL OF THE KOREAN SOCIETY FOR NONDESTRUCTIVE TESTING
FEA-based metal sphere signal map for mass estimation of simulated loose part in reactor coolant system
Progress in Nuclear Energy
Abstract For safety management of nuclear power plants, accurate impact mass estimation of loose ... more Abstract For safety management of nuclear power plants, accurate impact mass estimation of loose parts is very important. A center frequency method based on Hertz's impact theory, a frequency ratio method, and so forth are studied for mass estimation, but it is known that these approaches can hardly provide accurate information on impact response for identifying the impact source. In this paper, a finite element analysis (FEA) model to simulate the propagation behavior of the bending wave, generated by a metal ball impact, was validated by performing a series of impact tests and the corresponding finite element analyses for a flat plate as well as a curved plate (a half scale model of steam generator vessel). Various impact parameters such as amplitude, center frequency, group velocity and attenuation ratio of bending wave acceleration signal were investigated to verify the usefulness of the FEA model. Also, an FEA-based metal sphere signal map was developed, and then blind tests were performed to verify the map. This study provides an accurate simulation method for predicting the metal impact behavior and for building a metal sphere signal map, which can be used to estimate the mass of loose-parts on site in nuclear power plants.
Plate bending wave propagation behavior under metal sphere impact loading
Journal of Mechanical Science and Technology
A loose part can cause component damages and material wear on nuclear power plants; thus, a mass ... more A loose part can cause component damages and material wear on nuclear power plants; thus, a mass estimation of the loose part is crucial to safety management. A bending wave propagation of a structure under the loose part impact loading is precisely simulated to accurately estimate the mass of a loose part. Lamb’s general solution for an arbitrary impact force function and Hertz impact theory have been used to identify the characteristics of the bending wave that is impacted by a metallic loose part in reactor pressure boundary components. However, these approaches cannot provide accurate information on the acceleration response that is required to identify the impact source. In this study, the bending wave propagation behavior of plate structures under a simulated loose part (Metal sphere) impact loading was modeled using a Finite element analysis (FEA) technique. The characteristics (e.g., Maximum acceleration amplitude, primary frequency, and bending wave velocity) of the impact response signal from a metal sphere were analyzed with the FEA results and were verified with experimental results. In addition, the correlation between plate thickness and characteristic length was presented. Results from this study can be utilized to estimate the location and mass of a loose part for condition monitoring and diagnostics in nuclear power plants.
압축센싱을 적용한 회전체 시스템의 통계학적 상태진단
Condition Monitoring(CM) methods encounter a big data problem in processing the data collected th... more Condition Monitoring(CM) methods encounter a big data problem in processing the data collected through dense sensor networks with a high sampling rate. For this reason, compressive sensing technique has been introduced to improve efficiency and scalability of today"s CM procedures parallel to data acquisition improvement. In this study, Compressive sensing approach for condition monitoring is proposed to demonstrate efficiency in handling a large amount of data. For experiments, a built-in system was used for condition monitoring of a rotating system. During the experiments, all data were sampled with compressive sensing to obtain compressed data. Then we had performed condition monitoring only using compressed data without the reconstruction process. Experimental results show that the proposed method could effectively improve the speed of data processing and reduce energy consumption of sensing networks.
Transactions of the Korean Society for Noise and Vibration Engineering, 2006
Transactions of the Korean Society of Mechanical Engineers A, 2011
Transactions of the Korean Society for Noise and Vibration Engineering, 2015
In recent years, pattern recognition methods have been widely used by many researchers for fault ... more In recent years, pattern recognition methods have been widely used by many researchers for fault diagnoses of mechanical systems. The soundness of a mechanical system can be checked by analyzing the variation of the system vibration characteristic along with a pattern recognition method. Recently, the hidden Markov model has been widely used as a pattern recognition method in various fields. In this paper, the hidden Markov model is employed for the fault diagnosis of the mass un
Apparatus and method for generating and sensing torsional vibrations using magnetostriction
구동중인 자동차 배기계의 진동 특성 측정
Transactions of the Korean Society for Noise and Vibration Engineering, 2007
In this work, the operational deflection shape(ODS) of an automobile exhaust system is measured b... more In this work, the operational deflection shape(ODS) of an automobile exhaust system is measured by using a recently-developed magnetic sensor. The magnetic sensor is composed of a solenoid and two pairs of permanent magnets generating an antisymmetric magnetic field in the lateral direction inside the solenoid. Lateral movement of a ferromagnetic pipe inside the magnetic field of the suggested sensor induces an electromotive force in the solenoid corresponding to the lateral velocity of the pipe. Due to the simplicity and non-contact characteristics of the magnetic sensor, dynamic behaviors of the structures operating under high temperature such as an exhaust pipe can be efficiently observed. It is shown that the lateral ODS of an exhaust system can be successfully measured by the suggested sensors.
Improvement of Ride Comfort of the Excavator
SAE Technical Paper Series, 1997
Transactions of the Korean Society for Noise and Vibration Engineering, 2008
This paper suggests a non-contact sensor for measuring bending vibration of a non-metallic cylind... more This paper suggests a non-contact sensor for measuring bending vibration of a non-metallic cylinder in two orthogonal directions simultaneously. Recent research shows that a solenoid can pick up bending vibrations of a nonmetallic cylinder based on the reversed Lorentz force mechanism if an electrical conductive patch is attached to the cylinder. In this work, pairs of specially designed patches are used to make two independent paths for the current induced by bending vibrations, which enables the measurement of bending vibrations along two orthogonal directions simultaneously. The working performance of the developed sensor was verified by using two accelerometers.
Transactions of the Korean Society of Mechanical Engineers A, 2012
Wavelet-Based Wavenumber Filtering for Damage Detection and Thickness Estimation with Laser-Scanning
Structural Health Monitoring 2017
This paper presents the use of wavelet-based wavenumber filtering for damage detection and thickn... more This paper presents the use of wavelet-based wavenumber filtering for damage detection and thickness estimation with Laser-scanning sensing. A piezoelectric transducer provides an excitation at a fixed, single frequency to a structure. Laser Doppler Vibrometer (LDV) with a mirror-tilting device measures subsequent steadystate structural responses, resulting in the full standing wavefield of the structure at the excitation frequency. After then, wavelet-based wavenumber filtering is performed to obtain dominant wavenumber components, which could be used for indicative of structural damage. Mapping processes based on the dominant wavelet-based wavenumber is carried out for damaged area visualization. To estimate the depth of damages, Lamb wave equation is transformed into the wavenumber-thickness equation with the known structural parameters. With this process, the thickness and the thickness reduction by corrosion was accurately identified. Several experiments are performed on thin walled structures, including pipes and plates, with different types of damage, including corrosion and cracks. The experimental investigation into quantitative assessment of welded joints are also performed. The results show that the techniques are very effective in damage size and depth estimation with improved speed.
Measurement of Thickness of Wall-Thinned Plate using Acoustic Wavenumber Spectroscopy and Spatial Local Wavenumber Filtering
Structural Health Monitoring-an International Journal, 2017
The surface of a structure can generate cracks or wall-thinning, due to corrosion. This can event... more The surface of a structure can generate cracks or wall-thinning, due to corrosion. This can eventually lead to the fracture of the structure, which can trigger enormous fatality and property loss. Thereby, a laser imaging technology on such structures as thin plate structure, or piping which thickness is relatively thin in comparison to the area, has been steadily studied for the past 10 years. The most typical among the laser imaging technology is the pulse laser imaging. By using the same, a new technology for inspecting and imaging a desired area within a relatively short period of time was developed, so as to scan various structures including the thin-plate structure and piping. However, this method builds images by measuring waves reflected from defects, and have a time delay of a few milliseconds at each scanning point. Moreover, complexity of the systems is so high due to additional components such as laser focusing parts. This paper proposes laser imaging method with increas...
This paper describes the comparison study of wavenumber-based damage detection performance in ful... more This paper describes the comparison study of wavenumber-based damage detection performance in full field laser scanning techniques. Two types of excitation methods (guided waves and standing waves) are used for damage detection. For the standing wave based technique, the steady-state response could be obtained from a Laser Doppler Vibrometer and a mirror tilting device using a single fixed frequency (>50 kHz) from a mounted piezoelectric transducer. Time variant and invariant feature based damage visualization method is used to estimate damage size and depth. For the guided wave based approach, the same procedure is used except that a piezo actuator generates a tone-burst excitation. For the comparison of these two techniques, several experiments are performed on an aluminium plates and a composite plate which contain various types of damage, including corrosion and crack on an aluminium plate and debonding on a composite plate. The results demonstrate that pros and cons of these...
An Integrated Ultrasonic Imaging Technique using Laser Scanning System
Structural Health Monitoring-an International Journal, 2019
This paper presents an integrated methodology to improve the performance of laserscanning based d... more This paper presents an integrated methodology to improve the performance of laserscanning based damage detection for large structures with various obstacles. Two different ultrasonic imaging schemes are integrated in this technique, which involves the use of beamforming imaging with local scanning, along with standing wave based full field laser scanning. Two types of excitation methods (guided waves and standing waves) are used for damage detection. The wave field measurements are obtained from a Laser Doppler Vibrometer and a mirror tilting device using a single fixed frequency (>80 kHz) excitation from a mounted piezoelectric transducer. First, a newly developed beamforming imaging technique with frequency-wavenumber filtering using local guided wave measurement is performed to identify the presence and location of damage in large structures without full field measurements. Once the damage is identified, the steady-state response based full field laser scanning is used to quan...
Transactions of the Korean Society for Noise and Vibration Engineering
Multi Frequency Standing Wave Ultrasonic Imaging based Full-Field Laser Scanning
JOURNAL OF THE KOREAN SOCIETY FOR NONDESTRUCTIVE TESTING
Analysis of Bending Wave Propagation Behavior by Impact Loading in Plate Structure Using Finite Element Method
JOURNAL OF THE KOREAN SOCIETY FOR NONDESTRUCTIVE TESTING
Generation and Detection of Torsional Waves in a Rotating Shaft Using a Magnetostrictive Patch Array
Transactions of the Korean Society of Mechanical Engineers A
ABSTRACT
Crack Visualization Using Laser-scanning based Guided Ultrasonic and Standing Waves Response Image
JOURNAL OF THE KOREAN SOCIETY FOR NONDESTRUCTIVE TESTING
FEA-based metal sphere signal map for mass estimation of simulated loose part in reactor coolant system
Progress in Nuclear Energy
Abstract For safety management of nuclear power plants, accurate impact mass estimation of loose ... more Abstract For safety management of nuclear power plants, accurate impact mass estimation of loose parts is very important. A center frequency method based on Hertz's impact theory, a frequency ratio method, and so forth are studied for mass estimation, but it is known that these approaches can hardly provide accurate information on impact response for identifying the impact source. In this paper, a finite element analysis (FEA) model to simulate the propagation behavior of the bending wave, generated by a metal ball impact, was validated by performing a series of impact tests and the corresponding finite element analyses for a flat plate as well as a curved plate (a half scale model of steam generator vessel). Various impact parameters such as amplitude, center frequency, group velocity and attenuation ratio of bending wave acceleration signal were investigated to verify the usefulness of the FEA model. Also, an FEA-based metal sphere signal map was developed, and then blind tests were performed to verify the map. This study provides an accurate simulation method for predicting the metal impact behavior and for building a metal sphere signal map, which can be used to estimate the mass of loose-parts on site in nuclear power plants.
Plate bending wave propagation behavior under metal sphere impact loading
Journal of Mechanical Science and Technology
A loose part can cause component damages and material wear on nuclear power plants; thus, a mass ... more A loose part can cause component damages and material wear on nuclear power plants; thus, a mass estimation of the loose part is crucial to safety management. A bending wave propagation of a structure under the loose part impact loading is precisely simulated to accurately estimate the mass of a loose part. Lamb’s general solution for an arbitrary impact force function and Hertz impact theory have been used to identify the characteristics of the bending wave that is impacted by a metallic loose part in reactor pressure boundary components. However, these approaches cannot provide accurate information on the acceleration response that is required to identify the impact source. In this study, the bending wave propagation behavior of plate structures under a simulated loose part (Metal sphere) impact loading was modeled using a Finite element analysis (FEA) technique. The characteristics (e.g., Maximum acceleration amplitude, primary frequency, and bending wave velocity) of the impact response signal from a metal sphere were analyzed with the FEA results and were verified with experimental results. In addition, the correlation between plate thickness and characteristic length was presented. Results from this study can be utilized to estimate the location and mass of a loose part for condition monitoring and diagnostics in nuclear power plants.