• Journal of Radiation Protection and Research
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• v.41 no.2
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• pp.87-91
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• 2016

Background: A hand-held detector for an emergency response was developed for nuclide identification and to estimate the information of the ambient dose rate in the scene of an accident as well as the radioactivity of the contaminants. Materials and Methods: To achieve this, the most suitable sensor was first selected as a cadmium zinc telluride (CZT) semiconductor and the signal processing unit from a sensor and the signal discrimination and storage unit were successfully manufactured on a printed circuit board. Results and Discussion: The performance of the developed signal processing unit was then evaluated to have an energy resolution of about 14 keV at 662 keV. The system control unit was also designed to operate the CZT detector, monitor the detector, battery, and interface status, and check and transmit the measured results of the ambient dose rate and radioactivity. In addition, a collimator, which can control the inner radius, and the airborne dust sampler, which consists of an air filter and charcoal filter, were developed and mounted to the developed CZT detector for the quick and efficient response of a nuclear accident. Conclusion: The hand-held CZT detector was developed to make the in-situ gamma-ray spectrometry and its performance was checked to have a good energy resolution. In addition, the collimator and the airborne dust sampler were developed and mounted to the developed CZT detector for a quick and efficient response to a nuclear accident.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.11
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• pp.67-72
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• 2011

In this paper, we investigate the energy detector to detect a primary user. And employ the compressed sensing method to get the lower sampling rate than Nyquist sampling rate. In more wide bandwidth we using the small samples than Nyquist sampling rate samples to recover original signal. we investigate the performance of energy detector with compressive sensing method under suzuki channel. The performance is investigated by simulation and compared to that of conventional energy detector.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.12
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• pp.4600-4616
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• 2021

In cognitive radio networks where unlicensed secondary users opportunistically access to licensed spectrum unused by licensed primary users, spectrum sensing is one of the key issues in order to effectively use the frequency resource. For enhancing the sensing performance in energy detection-based spectrum sensing, spatial diversity based on multiple antennas is utilized. However, the sensing performance can be degraded when antennas are spatially correlated, resulting in inducing the harmful interference to primary users. To overcome this problem, in this paper, an advanced energy detector is proposed. In the proposed sensing method, a weight matrix based on the eigenvalues of the spatial channels without any prior information on the primary signals is defined and utilized. In numerical simulations, it is shown that the proposed detector outperforms the conventional detector with regard to false-alarm and detection probabilities when antenna are spatially correlated.

• Nuclear Engineering and Technology
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• v.52 no.10
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• pp.2346-2352
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• 2020

Dual-energy x-ray absorptiometry (DXA) is the noninvasive method to diagnose osteoporosis disease characterized by low bone mass and deterioration of bone tissue. Many global companies and research groups have developed the various DXA detectors using a direct photon-counting detector such as a cadmium zinc telluride (CZT) sensor. However, this approach using CZT sensor has some drawback such as the limitation of scalability by high cost and the loss of efficiency due to the requirement of a thin detector. In this study, a SiPM based DXA system was developed and its performance evaluated experimentally. The DXA detector was composed of a SiPM sensor coupled with a single LYSO scintillation crystal (3 × 3 × 2 ㎣). The prototype DXA detector was mounted on the dedicated front-end circuit consisting of a voltage-sensitive preamplifier, pulse shaping amplifier and constant fraction discriminator (CFD) circuit. The SiPM based DXA detector showed the 34% (at 59 keV) energy resolution with good BMD accuracy. The proposed SiPM based DXA detector showed the performance comparable to the conventional DXA detector based on CZT.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.421-424
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• 2017

This paper describes a full-wave rectifiers for energy harvesting circuit using vibration detector. The designed circuit operates only when the vibration is detected through the vibration detector and the active diode. When there is no vibration, the comparator is turned off to prevent leakage of energy stored in the $C_{STO}$. The energy stored in the capacitor is used to drive the level converter and the active diode. The energy stored in the capacitor is supplied to an active diode designed as an output power. The vibration detector is implemented with Schmitt Trigger and Peak Detector with Hysteresis function. The proposed circuit is designed in a CMOS 0.35um technology and its functionality has been verified through extensive simulations. The designed chip occupies $590{\mu}m{\times}583{\mu}m$.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1718-1733
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• 2023

The virtual Frisch-grid method for room-temperature radiation detectors has been widely used because of its simplicity and high performance. Recently, side electrodes were separately attached to each surface of the detectors instead of covering the entire detector surface with a single electrode. The side-electrode structure enables the measurement of the three-dimensional (3D) gamma-ray interaction in the detector. The positional information of the interaction can then be utilized to precisely calibrate the response of the detector for gamma-ray spectroscopy and imaging. In this study, we developed a 3D position-sensitive 5 × 5 × 12 mm³ cadmium-zinc-telluride (CZT) detector and applied a flattening method to correct detector responses. Collimated gamma-rays incident on the surface of the detector were scanned to evaluate the positional accuracy of the detection system. Positional distributions of the radiation interactions with the detector were imaged for quantitative and qualitative evaluation. The energy spectra of various radioisotopes were measured and improved by the detector response calibration according to the calculated positional information. The energy spectra ranged from 59.5 keV (emitted by ²⁴¹Am) to 1332 keV (emitted by ⁶⁰Co). The best energy resolution was 1.06% at 662 keV when the CZT detector was voxelized to 20 × 20 × 10.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3398-3402
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• 2022

We fabricated a 15 m long position-sensitive plastic scintillation optical fiber (PSOF) detector consisting of a PSOF, two photomultiplier tubes, four fast amplifiers, and a digitizer. A single PSOF was used as a sensing part to estimate the gamma-ray source position, and ¹³⁷Cs, an uncollimated solid-disk-type radioactive isotope, was used as a gamma-ray emitter. To improve the sensitivity, accuracy, and measurement time of a PSOF detector compared to those of previous studies, the performance of the amplifier was optimized, and the digital signal processing (DSP) was newly designed in this study. Moreover, we could measure very low dose rates of gamma-rays with high sensitivity and accuracy in a very short time using our proposed PSOF detector. The results of this study indicate that it is possible to accurately and quickly locate the position of a very low dose rate gamma-ray source in a wide range of contaminated areas using the proposed position-sensitive PSOF detector.

• Nuclear Engineering and Technology
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• v.5 no.3
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• pp.191-201
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• 1973

For fast neutron spectroscopy in MeV region, a recoil proton telescope detector was designed and constructed so as to increase in detection efficiency without appreciable deterioration in energy resolution by adopting a special type of recoil proton radiator which is a combination of a ring-shaped vertical radiator and a cone-shaped horizontal radiator at a certain geometry. A neutron stopper was built in the detector system to minimize the background due to direct exposure of the Si(Li) detectors to primary incident neutrons. The detection efficiency and the energy resolution calculated at various neutron energies and geometries are given and these characteristics of the detector system were tested by 14.1 MeV neutrons. As the calculation predicted, the relative detection efficiency in case of the combined radiator system is almost 2.2 times of that for a single, ring-shaped vertical radiator system. The calculated energy resolution is 3.7% FWHM, whereas the measured resolution was 3.9% which means resolution broadening of approximately. 30% was resulted by introducing a combined radiator system into the telescope. Increase in background less than 40% was also observed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.1020-1022
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• 2013

In this paper, proposed peak detector for the measurement of pulse radiation dose. The speed of the pulse radiation signal is the between a few ns and tens ns. Therefore, it is difficult to measure peak voltage. Peak Detector maintains the peak voltage generated from the sensor for a few ms and the converted signals can be easily measured using the ADC. The peak detector simulation results peak value remained of more than 1ms. Pulse radiation irradiation test results, a dose of $1.95{\times}10^6rad/s$ was measured.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.1030-1036
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• 2022

A high detection efficiency thermal neutron detector based on the ⁶LiF/ZnS(Ag) scintillation screens, wavelength-shifting fibers (WLSF) and Silicon photomultiplier (SiPM) readout is under development at China Spallation Neutron Source (CSNS) for the Engineering Material Diffractometer (EMD).A prototype with a sensitive volume of 180mm×192mm has been built. Signals from SiPMs are processed by the self-design Application Specific Integrated Circuit (ASIC). The performances of this detector prototype are as follows: neutron detection efficiency could reach 50.5% at 1 Å, position resolution of 3, the dark count rate <0.1Hz, the maximum count rate >200KHz. Such detector prototype could be an elementary unit for applications in the EMD detector arrays.