• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1945-1947
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• 2000

In this paper, we manufactured the detector which is detecting the periodical distribution of arrival time about pulsed leaky noise. The frequency range were analyzed optimally pulsed leaky noise in detector design. With results we can make the detector for leaky noise from the bad insulator.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.777-782
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• 2005

In this paper, we designed and fabricated a partial discharge (PD) detector to diagnose the soundness of CNCV cables by analyzing PD pulses and to predict discharge locations. The PD detector is consisted of a coupling network with a discharge free capacitor and a detection impedance, a voltage follower and a low noise amplifier. Lower cut-off frequency of the detector is adjusted at 175kHz to block AC voltage and to pass discharge pulse only. The discharge location could be obtained by the time of arrival method using travelling wave propagation theory. In a laboratory test on an eighty meter CV cable, we could position the discharge location within a two meter error.

• Journal of Biomedical Engineering Research
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• v.28 no.2
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• pp.300-305
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• 2007

In this study, we have studied the fabrication and the performance evaluation of digital radiation detector of the based on selenium (a-Se) prototype which is widely researched about recently. The detector was fabricated using amorphous selenium in the specification of active area size $7{\times}8.5"$, pixel pitch $139{\mu}m$, and 12 bit ADC. In order for the performance evaluation of the fabricated detector, we used radiation quality RQA 5 that is suggested by the International Electrotechnical Commission (IEC), and evaluated modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE). Concerning MTF measurement, we used slit camera (Nuclear Associates, Model : 07-624-2222), and evaluated in the slit method. Also so as to compare the performance evaluation on the detector fabricated in this study, we used Hologic Direct-Ray (DR-1000) and GE Revolution XQ/I system, and evaluated and compared in the same method MTF, NPS, and DQE which are image quality factors. And as a result, the MTF of each detector In Nyquist frequency were evaluated to be 58% (at 3.5 lp/mm) in the case of DR-1000 and 65% (at 2.5 lp/mm) in the case of XQ/I, and that for the detector fabricated in this study was evaluated to be 36% (at 3.51 lp/mm). Also in the case of DQE(0), the detector fabricated in this study, DR-1000 of Hologic company, and XQ/I system of GE company respectively were evaluated as 36%, 32%, and 50%.

• Journal of IKEEE
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• v.20 no.3
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• pp.299-302
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• 2016

In this paper, we designed the stack monitoring system with improved performance. To block the incoming pulse noise to the amplifier, shield and the power supply impedance are reduced and the power circuit is isolated. The control unit is developed with variable high voltage, adaptive gain, offset and threshold in order to match the scintillation detector characteristic to the apparatus. 300-1500V variable high voltage power circuit is configured applicable to various scintillation detector. Stack monitoring system with improved performance guarantee the efficiency and the reliability by considering the characteristic of various scintillation detector. Developed stack monitoring system is evaluated with certified testing equipment and shows excellent performance with respect to the uncertainty of the sensor test results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.4
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• pp.303-309
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• 2013

A low power 6-bit flash ADC that uses an input voltage range detection algorithm is described. An input voltage level detector circuit has been designed to overcome the disadvantages of the flash ADC which consume most of the dynamic power dissipation due to comparators array. In this work, four digital input voltage range detectors are employed and each input voltage range detector generates the specific clock signal only if the input voltage falls between two adjacent reference voltages applied to the detector. The specific clock signal generated by the detector is applied to turn the corresponding latched comparators on and the rest of the comparators off. This ADC consumes 68.82mW with a single power supply of 1.2V and achieves 4.9 effective number of bits for input frequency up to 1MHz at 500 MS/s. Therefore it results in 4.75pJ/step of Figure of Merit (FoM). The chip is fabricated in 0.13-um CMOS process.

• Nuclear Engineering and Technology
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• v.39 no.6
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• pp.725-730
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• 2007

This paper describes recently developed techniques for effective filtering of neutron detector signal noise. In this paper, three kinds of noise filters are proposed and their performance is demonstrated for the estimation of reactivity. The tested filters are based on the unilateral kernel filter, unilateral kernel filter with adaptive bandwidth and bilateral filter to show their effectiveness in edge preservation. Filtering performance is compared with conventional low-pass and wavelet filters. The bilateral filter shows a remarkable improvement compared with unilateral kernel and wavelet filters. The effectiveness and simplicity of the unilateral kernel filter with adaptive bandwidth is also demonstrated by applying it to the reactivity measurement performed during reactor start-up physics tests.

• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.141-147
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• 2017

Mechanical shim is an advanced technology for reactor power and axial offset control with control rod assemblies. To address the adverse accuracy impact on the ex-core power range neutron flux measurements-based axial offset control resulting from the variable positions of control rod assemblies, the lead-lag-compensated in-core self-powered vanadium detector signals are utilized. The prompt ${\gamma}$ current of self-powered detector is ignored normally due to its weakness compared with the delayed ${\beta}$ current, although it promptly reflects the flux change of the core. Based on the features of the prompt ${\gamma}$ current, a method for configuration of the lead-lag dynamic compensator is proposed. The simulations indicate that the method can improve dynamic response significantly with negligible adverse effects on the steady response. The robustness of the design implies that the method is of great value for engineering applications.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.232-234
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• 1996

The self-refresh mode was introduced as method to reduce power dissipation in DRAM. Because the data retention time of DRAM cell decreases as the ambient temperature rises, the internal period in self-refresh mode must be limited by retention capability at the highest temperature in DRAM specification. Because of this, at room temperature($25^{\circ}C$) unnecessary power dissipation happens, If the period of self-refresh could be modulated as temperature, it is possible to reduce the self-refresh current. In this paper, new temperature detector circuit is suggested as this purpose.

• Journal of Biomedical Engineering Research
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• v.26 no.1
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• pp.43-47
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• 2005

We have developed a small bore x-ray CT for small animal imaging with a linear x-ray detector array and small-scale slip rings. The linear x-ray detector array consists of 1024 elements of 400□m×400□m with a gadolinium oxysulfide (GOS) scintillator on top of them. To avoid use of expensive large diameter slip rings for projection data transmission from the X­ray detector to the image reconstruction system, we used the wireless LAN technology. The projection data are temporally stored in the data acquisition system residing on the rotating gantry during the scan and they are transmitted to the image reconstruction system after the scan. With the wireless LAN technology, we only needed to use small-scale slip rings to deliver the AC electric power to the X-ray generator and the power supply on the rotating gantry. The performances of the small animal CT system, such as SNR, contrast, and spatial resolution, have been evaluated through experiments using various phantoms. It has been experimentally found that the SNR is almost linearly proportional to the tube current and tube voltage, and the minimum resolvable contrast is less than 30 CT numbers at 40kVp/3.0㎃. The spatial resolution of the small animal CT system has been found to be about 0.9Ip/㎜. Postmortem images of a piglet is also presented.

• Proceedings of the Korean Nuclear Society Conference
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• 1999.05a
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• pp.18-18
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• 1999