• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.107.1-107.1
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• 2014

We have developed and commercialize a time-of-flight - medium energy ion scattering spectrometry (TOF-MEIS) system (model MEIS-K120). MEIS-K120 adapted a large solid acceptance angle detector that results in high collection efficiency, minimized ion beam damage while maintaining a similar energy resolution. In addition, TOF analyzer regards neutrals same to ions which removes the ion neutralization problems in absolute quantitative analysis. A TOF-MEIS system achieves $7{\times}10^{-3}$ energy resolution by utilizing a pulsed ion beam with a pulse width 350 ps and a TOF delay-line-detector with a time resolution of about 85 ps. TOF-MEIS spectra were obtained using 100 keV $He^+$ ions with an ion beam diameter of $10{\mu}m$ with ion dose $1{\times}10^{16}$ in ordinary experimental condition. Among TOF-MEIS applications, we report the quantitative compositional profiling of 3~5 nm CdSe/ZnS QDs, As depth profile and substitutional As ratio of As implanted/annealed Si, Ionic Critical Dimension (CD) for FinFET, Direct Recoil (DR) analysis of hydrogen in diamond like carbon (DLC) and InxGayZnzOn on glass substrate.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4636-4643
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• 2022

A time-of-flight and energy (TOF-E) detection system for the measurement of ²³⁶U accelerator mass spectrometry (AMS) has been developed to improve the ²³⁶U/²³⁸U sensitivity at Micro Analysis Laboratory, Tandem accelerator (MALT), The University of Tokyo. With observing TOF distribution of ²³⁵U, ²³⁶U and ²³⁸U, this TOF-E detection system has clearly separated ²³⁶U from the interference of ²³⁵U and ²³⁸U when measuring three kinds of uranium standards. In addition, we have developed a novel method combining kernel-based density estimation method and multi-Gaussian fitting method to estimate the ²³⁶U/²³⁸U sensitivity of the TOF-E detection system. Using this new estimation method, 3.4 × 10^-12 of ²³⁶U/²³⁸U sensitivity and 1.9 ns of time resolution are obtained. ²³⁶U/²³⁸U sensitivity of TOF-E detection system has improved two orders of magnitude better than that of previous gas ionization chamber. Moreover, unknown species other than uranium isotopes were also observed in the measurement of a surface soil sample, which has demonstrated that TOF-E detection system has a higher sensitivity in particle identification. With its high sensibility in mass determination, this TOF-E detection system could also be used in other heavy isotope AMS.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.437-441
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• 2022

In this study, we developed a neutron time-of-flight (nTOF) measurement system for a 1.7-MV tandem proton accelerator with a target covered with 300-nm-thick lithium (Li) layer. With implementation of beam chopping module after its ion source, the accelerator is configured to operate in pulsed-beam mode with a pulse width <50 ns at 20-kHz repetition rate. This enables the gamma flash-type nTOF measurement system to identify the neutron generated with 3-MeV proton beam energy. The nTOF system consists of a 30" cylindrical NaI(Tl) and four stilbene scintillation detectors. The NaI(Tl) scintillator is placed 50 cm from the Li target to measure the time of beam irradiation on the target, and the stilbene detectors are placed 2 and 2.4 m away to measure nTOF at each location. The nTOF system successfully measured the generated neutron energy at irradiated proton energies of 2.6 and 3.0 MeV with an average energy resolution of 15%.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.6
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• pp.93-99
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• 2017

In this research the TOF (time of flight) of ultrasonic signal is measured using Xilinx's Zynq SoC (system on chip). The TOF is calculated from the difference between periods during which RF (radio frequency) and ultrasonic signals come across a distance, and then travelling distance is obtained by multiplying the TOF by the ultrasonic speed in the air. For this purpose, a ultrasonic pulse is generated from a Zynq's internal ADC, a FIR (finite impulse response) filter, and a Kalman filter. And a RF reference pulse is generated from a RF interface. Based on baremetal multiprocessing, the Kalman filter and the RF interface are c-programmed on Zynq's dual processor cores, with other components fabricated on Zynq's FPGA. With this HW/SW co-design, both lower resource utilization and much smaller designing period were obtained than the HW design. As a design tool, Vivado IDE(integrated design environment) is used to design the whole signal processing system in hierarchical block diagrams.

• The KIPS Transactions:PartB
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• v.17B no.4
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• pp.287-294
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• 2010

TOF technique is one of the skills that can obtain the object's 3D depth information. But depth image has low resolution and fingertip occupy very small region, so, it is difficult to find the precise fingertip's 3D information by only using depth image from TOF camera. In this paper, we estimate fingertip's 3D location using Arm Model and reliable hand's 3D location information that is modified by hexahedron as hand model. Using proposed method we can obtain more precise fingertip's 3D information than using only depth image.

• YAKHAK HOEJI
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• v.57 no.6
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• pp.400-405
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• 2013

In this study, we measured the complex efficiency of a physiologically active antibody, a chelator and radiosiotopes using the ESI-TOF/Ms system for develop good radiopharmaceuticals. For a precise measurement, TLC is a low accuracy method. Loading of same amount of sample is difficult for each test, and work to quantify accurately the results obtained through TLC cannot be afforded compared to the use of other analytical instruments. The method of analysis using a mass spectrometer is capable of a mass analysis of proteins for quantitative analysis. The conjugates of the chelator (CHX-A- DTPA) and the antibody (IgG) were separated through MWCO, and were analyzed using ESI-TOF and MALDI-TOF mass spectrometry. The analysis using MALDI-TOF is roughly divided into measurements on mass spectrometry. When conjugating a small molecular weight of CHX-A-DTPA and a large molecular weight of IgG, distinguishing the peak of the conjugate and the peak of IgG was difficult. However, an ESI-TOF mass spectrometer system is capable of an analysis of mass by decentralizing the IgG. It is utilized as a technique for measuring the metabolic processes during conjugation and the stability evaluation of radiopharmaceuticals. When establishing this technique, the accuracy of the overall radiophar-maceutical analysis is expected to be able to be improved.

• Bulletin of the Korean Chemical Society
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• v.26 no.5
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• pp.763-768
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• 2005

An improved tandem time-of-flight (TOF) mass spectrometer for the photodissociation (PD) study of ions generated by matrix-assisted laser desorption ionization (MALDI), MALDI-TOF-PD-TOF, has been designed and constructed. Recording a full spectrum with better than unit mass resolution even in low mass range has been achieved without reflectron voltage stepping which was needed in the previous version. Other aspects of the improvement, such as those in the data system which now allow 10-100 times faster spectral acquisition than with the previous instrument, are described. Rationale for the ideas which have led to the improvements is presented also.

• Journal of the Korean Society of Radiology
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• v.14 no.7
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• pp.965-973
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• 2020

The purpose of this study was to quantitatively correlate the change of flow velocity and signal voiding in TOF-MRA. We made our phantom to control the flow velocity, and changed the flow velocity in 16 steps from 8.0 to 127.3 mc/s. The TOF-MRA test was performed using a 3.0T MRI system and the signal intensity was measured by classifying the signal voiding length and image into the In flow, Mid flow, and Out flow. The length of signal voiding was the longest when the flow velocity was 127.3 cm/s and the signal intensity decreased with increasing flow velocity(p<0.05). In flow(-.547) and Mid flow(-.643) were negatively correlated with flow velocitys(p<0.05). In conclusion, it was confirmed that the increase in flow velocity was a major factor causing signal voiding in TOF-MRA. In the future, this study will provide basic data when studying sequences and parameters to reduce signal voiding in models with a high flow velocity.

• Korean Journal of Digital Imaging in Medicine
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• v.15 no.1
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• pp.1-7
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• 2013

Purpose : The Carotid Angio inspection including Aortic arch applied to wide area is conducted as the Contrast Enhance MR Angiography(CEA) which is using a contrast medium. However it is a burden not only for someone such as infants, pregnant women and patients suffering from kidney failure but continuous use of contrast medium also can be a burden for patients who has been taken follow up inspection since diagnose lesion already. The purpose of this study is to estimate a usefulness of the Time of Flight (TOF) by comparing with CEA. Materials and methods : 10 patients with an average age of 58 (from 45 to 75) who had MRA inspection in our hospital were studied using 3.0 Tesla Aachieva (Philips, Netherland) MRI system and Sense Neuro-Vascular 16 Channels Coil. The same patient was inspected both TOF and CEA simultaneously. The TOF inspection included from Aortic arch to Willis Circle by connecting 3 TOF stacks and so did CEA inspection. The quantitative analysis was conducted through signal to noise ratio(SNR) and contrast to noise ratio(CNR) with soft tissue by setting up an area of interest on CCA bifurcatoin, ICA, ECA, MCA and VA concerning obtained image. In case of qualitative analysis, 3 radiological technologists and 1 radiologist evaluated 4 items (1: Visibility of the blood vessel, 2: Image distortion measure, 3: Overlapping measure with vein, 4: Peripheral blood vessel description measure) into five points scale (1: Very bad, 2: Bad, 3: Normal 4: Good, 5: Very good). Results : Results for the quantitative analysis was obtained by calculating the average of 5 ROIs in case of SNR and CNR separately. Results of SNR, TOF were generally measured higher than CEA (In case of TOF were 166.1, 205.2, 154.39, 172.23, 161.95, and CEA were 92.05, 95.43, 84.76, 73.69, 88.3). But according to the result of CNR, both TOF and CEA were measured similarly as 67.62, 106.71, 55.9, 73.74, 63.46 for TOF and 67.82, 71.19, 60.52, 49.45, 64.07 for CEA. Throughout every results of each ROI, SNR showed statistically meaningful consequence (0.050.05). In case of qualitative analysis the average of each evaluated item was 4.2points and 4.28points in the item1, 2.93points and 4.55points in the item2, 4.6points and 3.13points in the item3, 2.88points and 4.6points in the item4. According to the results TOF was measured higher in the item3 while in the item2 and item4 CEA was higher and in case of the item1, both CEA and TOF were similar. To sum up statistically meaningful results (p<0.05) were shown in the item2, item3 and item4 but not in the item1 (p>0.05). Conclusions : Both TOF and CEA are complementary because each inspection has pros and cons, but when inspect wide area including Aortic arch normally CEA is conducted. But TOF inspection also can be considered as alternative in terms of patients who has difficulty in the contrast medium such as infants, pregnant women and patients suffering from kidney failure and patients during follow up.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.225-227
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• 2002

In order to improve the accuracy of charged-particle radiation therapy, the beam energy was measured precisely using a TOF-system, and the range using a counter telescope system. A Si detector and a Ge detector were used to estimate the range straggling as a $\Delta$E and an E detector, respectively, because they have good energy resolution and the output pulse heights don't depend on the atomic number of detected particles. The results were compared with the theoretical values by a calculation code.