Proper understanding and knowledge of primary particle or grain size is of paramount importance i... more Proper understanding and knowledge of primary particle or grain size is of paramount importance in manufacturing processes as it directly affects various properties including mechanical behavior. Application of optical microscopy coupled with etching techniques has been used conventionally and in conjunction with color metallography (polarized microscopy) has been the preferred method for grain size measurement. An advanced technique as an alternative to light microscopy is using electron backscatter diffraction (EBSD). A comparison is made between these two techniques using Al-7Si alloy produced with various casting techniques to highlight the cost and time of the sample preparation and analysis for both techniques. Results showed that color metallography is certainly a faster technique with great accuracy and a much cheaper alternative in comparison with EBSD.
A titanium alloy implant of appropriate pore size can potentially enhance osseointegration and so... more A titanium alloy implant of appropriate pore size can potentially enhance osseointegration and soft tissue integration. However, the human clinical application of such implants has not been reported. Here, we present a case of limb salvage surgery for a bone tumor using customized three-dimensional (3D)-printed Ti6Al4V radius and ulna implants. The patient presented with local recurrence at the proximal junction of the ulna and underwent a re-wide excision. Single forearm bone surgery was performed using another 3D-printed implant after resection of the recurrent tumor with an ulnar implant. Host osseointegration and soft tissue integration of the retrieved implant were quantified through histological evaluation. The total tissue integration rates of the implant at the proximal and distal bone junctions were 45.96% and 15.03%, respectively. The mesh structure enhanced bone integration by up to 10.81% in the proximal and by up to 8.91% in the distal bone junction. Furthermore, the so...
Globally, harmful algal blooms (HABs) caused by marine phytoplankton pose a significant threat to... more Globally, harmful algal blooms (HABs) caused by marine phytoplankton pose a significant threat to human health and result in enormous economic loss. Many strategies have been implemented for their detection, management, and control. One such instrument is the red-tide acoustic sensing system (RASS) which utilizes a backscattered acoustic signal to detect microalgal cells in the water column, proving to be a cheap and easy tool for the HABs detection. In the current study, five RASSs were deployed at fish farms located in HAB-occurring areas of South Korea during the summer of 2018, and their performance examined for the HABs detection. From 26 July to 6 August 2018, the dinoflagellate Cochlodinium polykrikoides was the most abundant HAB species across all locations. A standard curve between the relative received level (RRL) of acoustic intensity as measured by RASS and cell densities of HAB species was constructed (R 2 = 0.846) and was successfully applied to quantify the HAB cell density. The RRL values noticeably increased from July 25, 2018 and decreased from August 1. The RRL values corresponding to warning level of HABs (≥ 100 cells mL −1) were not measured after August 5. The highest 22 RRL was recorded on July 29, which corresponded to 2,782 cells mL −1. To evaluate the efficacy and accuracy of the RASS, a significant correlation (R 2 = 0.997) between HAB cell abundance and backscattered acoustic signals was confirmed. Results from our study show that the RASS can produce accurate, real-time bloom data, providing significant advantages for the warning of HABs.
The Journal of the Acoustical Society of America, 2015
Temporal variations of acoustic transmission loss (TL) affected by internal tide are simulated us... more Temporal variations of acoustic transmission loss (TL) affected by internal tide are simulated using oceanic data measured at two sites in the southern sea of Jeju island. Temperature and salinity were measured every hour for 25 hours during July 27th and 28th 2009. The periodic fluctuation of temperature due to the internal tide was observed and its vertical displacement was more than 10m. In order to investigate the variation of TL, acoustic propagation between two measurement sites (3.8 km distance) was computed at a source depth of 10 m. Acoustic propagation model RAM was used for the simulation. Standard deviations of TL variation were 4.2 dB and 3.7 dB for center frequencies of 100 Hz and 1 kHz with 1/3 octave band, respectively. The lower frequency was more correlated with the tidal period than the higher one. Detection range was also varied by the internal tidal, up to 1 km for the 60 dB detection level. These results imply that tidal variation of TL should be considered for acoustic researches at...
Effect of Mn addition, Ti/Cr ratio and heat treatment on structural and hydrogen storage characte... more Effect of Mn addition, Ti/Cr ratio and heat treatment on structural and hydrogen storage characteristics of Ti-V-Cr alloys were investigated. It was found that the hydrogen absorption rate of Ti33V33Cr34 alloy was considerably fast and more than 95 % of the hydrogen was absorbed within 10 min. The hydrogen desorption capacity was improved when the Mn contained less than 15 at.%. The best effective hydrogen storage capacity of Ti33V33Cr19Mn15 alloy was 2.48 wt.%. The plateau pressure increased with Ti/Cr ratio decreasing for the Ti(33-y)V33Cr(19+y)Mn15 alloys, however, the maximum hydrogen storage capacity decreased. The Ti31V33Cr21Mn15 alloy increased the plateau pressure and decreased the plateau slope after annealing at 1200 ℃ for 10 h.
Proper understanding and knowledge of primary particle or grain size is of paramount importance i... more Proper understanding and knowledge of primary particle or grain size is of paramount importance in manufacturing processes as it directly affects various properties including mechanical behavior. Application of optical microscopy coupled with etching techniques has been used conventionally and in conjunction with color metallography (polarized microscopy) has been the preferred method for grain size measurement. An advanced technique as an alternative to light microscopy is using electron backscatter diffraction (EBSD). A comparison is made between these two techniques using Al-7Si alloy produced with various casting techniques to highlight the cost and time of the sample preparation and analysis for both techniques. Results showed that color metallography is certainly a faster technique with great accuracy and a much cheaper alternative in comparison with EBSD.
A titanium alloy implant of appropriate pore size can potentially enhance osseointegration and so... more A titanium alloy implant of appropriate pore size can potentially enhance osseointegration and soft tissue integration. However, the human clinical application of such implants has not been reported. Here, we present a case of limb salvage surgery for a bone tumor using customized three-dimensional (3D)-printed Ti6Al4V radius and ulna implants. The patient presented with local recurrence at the proximal junction of the ulna and underwent a re-wide excision. Single forearm bone surgery was performed using another 3D-printed implant after resection of the recurrent tumor with an ulnar implant. Host osseointegration and soft tissue integration of the retrieved implant were quantified through histological evaluation. The total tissue integration rates of the implant at the proximal and distal bone junctions were 45.96% and 15.03%, respectively. The mesh structure enhanced bone integration by up to 10.81% in the proximal and by up to 8.91% in the distal bone junction. Furthermore, the so...
Globally, harmful algal blooms (HABs) caused by marine phytoplankton pose a significant threat to... more Globally, harmful algal blooms (HABs) caused by marine phytoplankton pose a significant threat to human health and result in enormous economic loss. Many strategies have been implemented for their detection, management, and control. One such instrument is the red-tide acoustic sensing system (RASS) which utilizes a backscattered acoustic signal to detect microalgal cells in the water column, proving to be a cheap and easy tool for the HABs detection. In the current study, five RASSs were deployed at fish farms located in HAB-occurring areas of South Korea during the summer of 2018, and their performance examined for the HABs detection. From 26 July to 6 August 2018, the dinoflagellate Cochlodinium polykrikoides was the most abundant HAB species across all locations. A standard curve between the relative received level (RRL) of acoustic intensity as measured by RASS and cell densities of HAB species was constructed (R 2 = 0.846) and was successfully applied to quantify the HAB cell density. The RRL values noticeably increased from July 25, 2018 and decreased from August 1. The RRL values corresponding to warning level of HABs (≥ 100 cells mL −1) were not measured after August 5. The highest 22 RRL was recorded on July 29, which corresponded to 2,782 cells mL −1. To evaluate the efficacy and accuracy of the RASS, a significant correlation (R 2 = 0.997) between HAB cell abundance and backscattered acoustic signals was confirmed. Results from our study show that the RASS can produce accurate, real-time bloom data, providing significant advantages for the warning of HABs.
The Journal of the Acoustical Society of America, 2015
Temporal variations of acoustic transmission loss (TL) affected by internal tide are simulated us... more Temporal variations of acoustic transmission loss (TL) affected by internal tide are simulated using oceanic data measured at two sites in the southern sea of Jeju island. Temperature and salinity were measured every hour for 25 hours during July 27th and 28th 2009. The periodic fluctuation of temperature due to the internal tide was observed and its vertical displacement was more than 10m. In order to investigate the variation of TL, acoustic propagation between two measurement sites (3.8 km distance) was computed at a source depth of 10 m. Acoustic propagation model RAM was used for the simulation. Standard deviations of TL variation were 4.2 dB and 3.7 dB for center frequencies of 100 Hz and 1 kHz with 1/3 octave band, respectively. The lower frequency was more correlated with the tidal period than the higher one. Detection range was also varied by the internal tidal, up to 1 km for the 60 dB detection level. These results imply that tidal variation of TL should be considered for acoustic researches at...
Effect of Mn addition, Ti/Cr ratio and heat treatment on structural and hydrogen storage characte... more Effect of Mn addition, Ti/Cr ratio and heat treatment on structural and hydrogen storage characteristics of Ti-V-Cr alloys were investigated. It was found that the hydrogen absorption rate of Ti33V33Cr34 alloy was considerably fast and more than 95 % of the hydrogen was absorbed within 10 min. The hydrogen desorption capacity was improved when the Mn contained less than 15 at.%. The best effective hydrogen storage capacity of Ti33V33Cr19Mn15 alloy was 2.48 wt.%. The plateau pressure increased with Ti/Cr ratio decreasing for the Ti(33-y)V33Cr(19+y)Mn15 alloys, however, the maximum hydrogen storage capacity decreased. The Ti31V33Cr21Mn15 alloy increased the plateau pressure and decreased the plateau slope after annealing at 1200 ℃ for 10 h.
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