• Smart Structures and Systems
• /
• v.26 no.5
• /
• pp.657-666
• /
• 2020

A rotational pulse-echo ultrasonic propagation imager that can inspect cylindrical specimens for material nondestructive evaluations is proposed herein. In this system, a laser-generated ultrasonic bulk wave is used for inspection, which enables a clear visualization of subsurface defects with a precise reproduction of the damage shape and size. The ultrasonic waves are generated by a Q-switched laser that impinges on the outer surface of the specimen walls. The generated waves travel through the walls and their echo is detected by a Laser Doppler Vibrometer (LDV) at the same point. To obtain the optimal Signal-to-Noise Ratio (SNR) of the measured signal, the LDV requires the sensed surface to be at a right angle to the laser beam and at a predefined constant standoff distance from the laser head. For flat specimens, these constraints can be easily satisfied by performing a raster scan using a dual-axis linear stage. However, this arrangement cannot be used for cylindrical specimens owing to their curved nature. To inspect the cylindrical specimens, a circular scan technology is newly proposed for pulse-echo laser ultrasound. A rotational stage is coupled with a single-axis linear stage to inspect the desired area of the specimen. This system arrangement ensures that the standoff distance and beam incidence angle are maintained while the cylindrical specimen is being inspected. This enables the inspection of a curved specimen while maintaining the optimal SNR. The measurement result is displayed in parallel with the on-going inspection. The inspection data used in scanning are mapped from rotational coordinates to linear coordinates for visualization and post-processing of results. A graphical user interface software is implemented in C++ using a QT framework and controls all the individual blocks of the system and implements the necessary image processing, scan calculations, data acquisition, signal processing and result visualization.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2014.05a
• /
• pp.695-698
• /
• 2014

As most the scanning systems developed until now provide radiation scan plane images of the inspected objects, there has been a limitation in judging exactly the shape of the objects inside a logistics container exactly with only 2-D radiation image information. Two 2-dimensional radiation images which have different disparity values are acquired from a newly designed stereo image acquisition system which has one additional line sensor to the conventional system. Using a matching algorithm the 3D reconstruction process which find the correspondence between the images is progressed. In this paper, we proposed a new volume based 3D reconstruction algorithm and experimental results show the proposed new volume based reconstruction technique can provide more efficient visualization for cargo inspection. The proposed technique can be used for the development of the high speed and more efficient non-destructive auto inspection system.

• Progress in Medical Physics
• /
• v.27 no.3
• /
• pp.125-130
• /
• 2016

Dual energy computed tomography (DECT) is used to classify two materials and quantify the mass density of each material in the human body. An energy modulation filter based DECT could acquire two images, which are generated by the low- and high-energy photon spectra, in one scan, with one tube and detector. In the case of DECT using the energy modulation filter, the filter should perform the optimization process for the type of materials and thicknesses for generating two photon spectra. In this study, Geant4 Monte-Carlo simulation toolkit was used to execute the optimization process for determining the property of the energy modulation filter. In the process, various materials used for the energy modulation filter are copper (Cu, $8.96g/cm^3$), niobium (Nb, $8.57g/cm^3$), stannum (Sn, $7.31g/cm^3$), gold (Au, $19.32g/cm^3$), and lead (Pb, $11.34g/cm^3$). The thickness of the modulation filter varied from 0.1 mm to 1.0 mm. To evaluate the overlap region of the low- and high-energy spectrum, Geant4 Monte-Carlo simulation is used. The variation of the photon flux and the mean energy of photon spectrum that passes through the energy modulation filter are evaluated. In the primary photon spectrum of 80 kVp, the optimal modulation filter is a 0.1 mm lead filter that can acquire the same mean energy of 140 kVp photon spectrum. The lead filter of 0.1 mm based dual energy CBCT is required to increase the tube current 4.37 times than the original tube current owing to the 77.1% attenuation in the filter.

• Journal of Magnetics
• /
• v.21 no.2
• /
• pp.286-292
• /
• 2016

This study evaluates the change of computer tomography (CT) number in the case of the metal artifact reduction (MAR) algorithm, using the phantom. The images were obtained from dual CT using a gammex 467 tissue characterization phantom, which is similar to human tissues. The test method was performed by dividing pre and post MAR algorithm and measured CT values of nonmagnetic materials within the phantom. In addition, the changes of CT values for each material were compared and analyzed after measuring CT values up to 140 keV, using the spectral HU curve followed by CT scan. As a result, in the cases of N rod (trabecular bone) and E rod (trabecular bone), the CT numbers decreased as keV increasing but were constant above 90 keV. In the cases of I rod (dense bone) and K rod (dense bone), the CT numbers also decreased as keV increased but were uniform above 90 keV. The CT numbers from 40 keV to 140 keV were consistent in the cases of J rod (liver), D rod (liver), L rod (muscle), and F rod (muscle). For A rod (adipose), G rod (adipose), B rod (breast) and O rod (breast), the CT numbers increased as keV increased but were constant after 90 keV. The CT numbers from 40 keV to 140 keV were consistent in the cases of C rod (lung (exhale)), P rod (lung (exhale)), M rod (lung (inhale)) and H rod (lung (exhale)). Conclusively, because dual CT exhibits no changes in image quality and is able to analyze nonmagnetic materials by measuring the CT values of various materials, it will be used in the future as a useful tool for the diagnosis of lesions.

• Journal of the Korean Society of Radiology
• /
• v.5 no.2
• /
• pp.51-58
• /
• 2011

This research compared and analyzed the heart rate of the patient in which the LVEF value is 40% less than and normal patient. When as for LVEF 40% or less becomes to each heart rate and LVEF in a relation, we can know that the time to reach 100HU hangs long. Therefore, in patients, that is 40% less than, when setting up the Premonitoring delay, we could know to could give 5 primary solid phrases. It is seen that subsequently an addition injected 40cc as to Saline, to all patients by 4cc/sec speeds after injecting the capacity of Scan time ${\times}$ 4cc + 30cc with 4cc/sec speeds. And HR excludes 80 or greater in 40% less than, the contrast agent shows the large-scale difference. In addition, in 40% less than, it could predict that the time difference was big and the contrast agent was already out in the Left ventricle Wash- when the contrast agent reached 100HU and Scan was started There is a wide difference between under 40% LVEF and normal. when starting scan from low LVEF patients. So, Injection contrast media protocol Should be determined to CCTA. And then In case of low LVEF is recommended to more low Pitch than routine Pitch because we should reduce scan failed in accordance with low LVEF.

• Proceedings of the KIPE Conference
• /
• 2007.11a
• /
• pp.215-217
• /
• 2007

Recently, the demand for high definition TV is being increased by beginning of the digital broadcasting. The higher resolution of PDP is, the longer addressing time become, then, the sustain period for display image decreases. Because of the reason, dual-scan method which synchronously write information of an image on top and bottom of the screen is used for the high definition PDP. However, as the price competition of PDP becomes severe, we can`t avoid turning to a single-scan method which uses only a half of an expensive address IC. Accordingly, the sustain period becomes much shorter than prior method. In case of XGA level, it is impossible to display, eventually. In this paper, we are going to prove usefulness by realizing negative reset waveform and the driving circuit for high speed addressing.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.734-738
• /
• 2003

The addressing time should be reduced by modifying cell and/or driving method in order to replace the dual scan system by single scan and increase the luminance in large ac plasma display panel(PDP). In this paper, the relationships between of discharge cell structure and addressing time in ac PDP are investigated. It is found out that the addressing time was decreased with decreasing gap of ITO electrode and thickness of transparence dielectric layer on the front glass. The decrease rates were 4% per $10{\mu}m$ and 4% per $5{\mu}m$, respectively. Also in cases of decreasing height of barrier rip and thickness of white dielectric layer on the rear glass, addressing times were at the rate of 4% per $10{\mu}m$ and 4% per $2{\mu}m$, respectively.

• Journal of electromagnetic engineering and science
• /
• v.18 no.3
• /
• pp.199-205
• /
• 2018

In this study, an imaging mode of the modified SweepSAR is proposed with performance analysis for a high-resolution and wide swath coverage. To reduce the overall antenna size required for the solution of the azimuth ambiguity problem, different pulse repetition frequencies (PRFs) are utilized for different transmitters, respectively. For each imaging mode, system performance parameters are used for simulation, analysis, wide swath prediction, and comparison between conventional ScanSAR mode and SweepSAR mode based on scanon-receive (SCORE). The system parameters of AASR, RASR, and NESZ will be estimated and suggested on the imaging mode by using appropriate reflector antenna with the effectiveness of a modified SweepSAR employing dual channels.

• Journal of Biomedical Engineering Research
• /
• v.29 no.6
• /
• pp.431-435
• /
• 2008

Quantitative information of a three dimensional(3D) kinematics of joint is very useful in knee joint surgery, understanding how knee kinematics related to joint injury, impairment, surgical treatment, and rehabilitation. In this paper, an automated 2D/3D image matching technique was developed to estimate the 3D in vivo knee kinematics using dual X-ray images. First, a 3D geometric model of the knee was reconstructed from CT scan data. The 3D in vivo position and orientation of femoral and tibial components of the knee joint could be estimated by minimizing the pixel by pixel difference between the projection images from the developed 3D model and the given X-ray images. The accuracy of the developed technique was validated by an experiment with a cubic phantom. The present 2D/3D image matching technique for the estimation of in vivo joint kinematics could be useful for pre-operative planning as well as post-operative evaluation of knee surgery.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.41 no.10
• /
• pp.17-22
• /
• 2004

We developed a new ANGLED display driving method which used both amplitude and pulse width modulation. For pulse width modulation, we divided a picture frame time into S sub-frames. For amplitude modulation, we used three OLED luminance(or current) levels which were controlled by TFT's gate voltages. By combining these two modulation methods, we obtained 35(=243) grey levels. And we designed a new data electrode driving circuit block with two shift registers without using DAC's. To verify the feasibility, we simulated the key circuit components by HSpice with TFT parameters extracted from current-voltage characteristics of 6${\mu}{\textrm}{m}$ channel length polysilicon TFT's. From the simulation results, we found that 320${\times}$240, dual scan, 243 grey level AMOLED display can be designed with this method.