• Nuclear Engineering and Technology
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• 제56권2호
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• pp.575-600
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• 2024

During an earthquake on December 29th 2020, the Krško NPP automatically shutdown due to the trigger of the negative neutron flux rate signal on the power range nuclear instrumentation. From the time course of the detector signal, it can be concluded that the fluctuation in the detector signal may have been caused by the mechanical movement of the ex-core neutron detectors or the pressure vessel components rather than the actual change in reactor power. The objective of the analysis was to evaluate the sensitivity of the neutron flux at the ex-core detector position, if the detector is moved in the radial or axial direction. In addition, the effect of the core barrel movement and core inside the baffle movement in the radial direction were analysed. The analysis is complemented by the calculation of the thermal and total neutron flux gradient in radial, axial and azimuthal directions. The Monte Carlo particle transport code MCNP was used to study the changes in the response of the ex-core detector for the above-mentioned scenarios. Power and intermediate-range detectors were analysed separately, because they are designed differently, positioned at different locations, and have different response characteristics. It was found that the movement of the power range ex-core detector has a negligible effect on the value of the thermal neutron flux in the active part of the detector. However, the radial movement of the intermediate-range detector by 5 cm results in 7%-8% change in the thermal neutron flux in the active part of the intermediate-range detector. The analysis continued with an evaluation of the effects of moving the entire core barrel on the ex-core detector response. It was estimated that the 2 mm core barrel radial oscillation results in ~4% deviation in the power and intermediate-range detector signal. The movement of the reactor core inside baffle can contribute ~6% deviation in the ex-core neutron detector signal. The analysis showed that the mechanical movement of ex-core neutron detectors cannot explain the fluctuations in the ex-core detector signal. However, combined core barrel and reactor core inside baffle oscillations could be a probable reason for the observed fluctuations in the ex-core detector signal during an earthquake.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1771-1774
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• 2005

Recently, RFID has become popular in the field of remote sensing applications. Location awareness is one of the most important keys to deploying RFID for advanced object tracking. Generally, multiple reference RF stations or additional sensors are used for the location sensing with RFID, but, particularly in indoor environments, spatial layout and cost problems limit the applicability of those approaches. In this paper, we propose a novel method for location sensing with active RFID systems not requiring the need for reference stations or additional sensors. The system triangulates the position of RF signal source using the signal pattern of the loop antenna connected to the power detector. The power detector consists of a signal strength detector and a signal analysis unit. The signal analysis unit indicates the signal strength and serial number using the signal from the strength detector, and provides the direction of the signal to the application target. We designed three different signal analysis units depending on the threshold type. The developed system can sense the direction to the transponder located over 10 m away within the maximum error of $5^{\circ}$. It falls within a reasonable range in our normal office environment.

• 융합신호처리학회논문지
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• 제7권4호
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• pp.184-188
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• 2006

본 논문은 협대역의 위성통신 수신신호 전력을 측정하여 이동형 위성통신 안테나를 추적제어하기 위한 DSP 기반의 협대역 위성통신 신호전력 검출기를 제안한다. 기존의 아날로그 검출방식에 의한 협대역 위성통신 신호전력 검출기는 위성 전파경로 상에서 발생되는 반송파의 중심주파수 천이로 인해 고정된 아날로그 필터대역을 통과하여 검출되는 신호 전력의 오차가 심하고 전송 신호의 대역폭 가변에 따른 아날로그 필터의 대역폭을 변경하기가 용이하지 않다. 따라서 이러한 반송파 주파수 천이에 영향 받지 않고 가변 하는 신호 대역폭에 대응하는 필터를 실시간으로 프로그래머블하게 지원하기 위하여 DSP 기반의 협대역 디지털 위성통신 신호전력 검출기를 제안하였다. 제안된 협대역 위성통신 신호전력 검출 알고리즘은 FFT를 이용하여 주파수 천이된 협대역 위성통신 신호의 주파수를 탐색하고 프로그래머블한 디지털 필터를 선택하여 필터링한 다음, 일정구간 주기로 신호전력을 계산하여 12비트 해상도로 출력하는 기능을 가진다. TMS320C5402 DSP 칩을 기반으로 설계 제작된 신호전력 검출기의 실제 시험을 통하여 제시된 요구기능과 규격을 만족하면서 동작함을 검증하였고 실용성을 확인하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.427-430
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• 2003

The properties of digital X-ray detectors depend on the absorption extent of X-rays, the generated signal of each X-ray photon and the distribution of the generated signal between pixels. In digital X-ray detector with single layer, signal is generated by X-ray photon captured in photoconductor. In X-ray detector with multi structure that scintillator formed above the top of photoconductor, signal is generated both by X-ray photon captured each in scintillator and photoconductor. X-ray detector with multi structure is generated more signal than single layer detector. In this paper, we simulated absorption fraction of X-ray detector with multi-layer using Monte Carlo program. The results compared with single-layer detector to be formed scinillator or photoconductor.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1996년도 학술대회
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• pp.9-15
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• 1996

In this paper, we propose a new detector based on the median-shift sign. We call it the median-shift sign (MSS) detector, which is an extension of the classical sign detector. We first analyze the problem of detecting a dc signal in noise of known probability density function (pdf). The MSS detector with the optimum median-shift value, the optimum MSS detector, performs better than the sign detector in Gaussian noise: it has the best performance among the detectors compared in Laplacian and Cauchy noise. It is shown that the MSS detectors with constant median-shift values are nearly equal to the optimum MSS detector. We also analyze the problem of detecting a dc signal when only partial information is available on the noise. The MSS detectors with constant median-shift values are almost equal to the sign detector in Gaussian noise: they perform better than the sign and Wilcoxon detectors for most signal ranges in Laplacian and Cauchy noise.

• Journal of Communications and Networks
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• 제16권5호
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• pp.485-492
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• 2014

Spectrum sensing for cognitive-radio applications may use a matched-filter detector (in the presence of full knowledge of the signal that may be transmitted by the primary user) or an energy detector (when that knowledge is missing). An intermediate situation occurs when the primary signal is imperfectly known, in which case we advocate the use of a linear-quadratic detector. We show how this detector can be designed by maximizing its deflection, and, using moment-bound theory, we examine its robustness to the variations of the actual probability distribution of the inaccurately known primary signal.

• Nuclear Engineering and Technology
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• 제29권6호
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• pp.451-458
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• 1997

Signal shapes from a closed-ended coaxial HPGe detector are investigated by numerical methods. The detector used in this study has a volume of 72 ㎤ with relative efficiency of 15%. The electric field and potential distributions in the detector are determined by solving the Poisson equation at the depletion and operating bias. Hence the time dependent signal shapes induced on the electrode are obtained from the energy balance consideration and tv solving the equation of motion for the charge carriers. For various initial positions of a charge carrier pair, the collection times of induced charge vary in the range of 70 - 404 nsec.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.609-611
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• 1996

Zero-Cross Detector makes pilot signal to control the power to CEDM(Control Element Drive Mechanism). Existing Zero-Cross Detectors has had a problem which can cause unexpected reactor trip resulted from fluctuating frequency of input signal coming from M/G Set. The existing Zero-Cross Detector can't work properly when power frequency is varying because it was designed to work under stable M/G Set operation, and produces wrong pilot signal and output voltage. In this report the Zero-Cross Detector is improved to resolve voltage fluctuating problem by using new devices such as digital noise filtering circuit, variable cycle compensator and alarm circuit. And through the performance verification it shows that new circuit is better than old one. If suggested detector is applied to plant, it is possible to use it under House Load Operation because stable voltage can be generated by new Zero-Cross Detector.

• Journal of information and communication convergence engineering
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• 제10권2호
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• pp.175-180
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• 2012

This paper presents a blind watermark detection scheme for an additive watermark embedding model. The proposed estimation-correlation-based watermark detector first estimates the embedded watermark by exploiting non-Gaussian of the real-world audio signal and the mutual independence between the host-signal and the embedded watermark and then a correlation-based detector is used to determine the presence or the absence of the watermark. For watermark estimation, blind source separation (BSS) based on independent component analysis (ICA) is used. Low watermark-to-signal ratio (WSR) is one of the limitations of blind detection with the additive embedding model. The proposed detector uses two-stage processing to improve the WSR at the blind detector; the first stage removes the audio spectrum from the watermarked audio signal using linear predictive (LP) filtering and the second stage uses the resulting residue from the LP filtering stage to estimate the embedded watermark using BSS based on ICA. Simulation results show that the proposed detector performs significantly better than existing estimation-correlationbased detection schemes.

• 한국위성정보통신학회논문지
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• 제1권1호
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• pp.59-64
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• 2006

본 논문에서는 직접 변환 방식인 six-port의 RF 출력 신호를 검파하고 요구 대역폭에서 입력 주파수 신호에 대한 진폭 및 위상 신호를 선형적으로 출력하는 광역 power detector를 설계 제작한다. Six-port 출력단에 접속되는 power detector는 높은 정합도를 갖고 반사파로 인한 Six-port 간 위상 불일치를 방지하고, 넓은 대역폭에서 낮은 VSWR을 유지하여야 하는 광역 특성을 갖는 power detector 설계가 필요하다. 광역 정합을 위하여 사용 주파수 대역에 따라 강제 정합과 다단 LC 정합 회로, 그리고 isolator를 사용한 낮은 VSWR 특성을 갖는 설계 방법을 비교 분석한다. 설계 제작된 power detector의 주파수 대역에 대한 동적 동작 영역(dynamic range) 성능을 측정하여 Six-port의 수신 전송 신호 검파기로 활용될 수 있는 타당성을 평가한다.