• 디지털융복합연구
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• 제16권11호
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• pp.115-122
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• 2018

국내에서 전기 화재의 70% 이상이 아크로 인하여 발생하고 있다. 본 논문에서는 이를 예방하기 위한 방안을 마련하기 위하여 기존의 누전 차단기에 관한 기술기준 및 규정을 분석하였으며, 아크 검출기에 관한 기술기준 및 규정은 아크의 특성을 고려하여 기존의 누전 차단기에 관한 기술기준 및 규정과는 별도로 제정되어야 한다는 결론을 얻었다. 따라서 본 논문에서는 아크 검출기 관련 규정은 기존 누전 차단기의 관련 규정에 추가 되거나 이것과 별개인 규정으로 제정되어야 한다고 제안하였다. 특히 아크로 인한 화재를 예방하기 위해서는 아크 검출기의 신속한 보급이 필요하고 그 설치를 의무화하는 것이 바람직하다. 따라서 이 같은 여건을 고려했을 때 기존 누전차단기 규정에 아크 검출기 관련 사항들을 추가할 것을 제안하였다. 아크 검출기의 기술 기준에는 아크의 판단 규격과 차단 임계치, 그리고 차단기가 반응하지 말아야 할 불요신호의 범위 등이 반드시 반영되어야 한다.

• 전기학회논문지
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• 제56권3호
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• pp.615-622
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• 2007

In general, Harris detector is commonly used for finding salient points in watermarking systems using feature points. Harris detector is a kind of combined comer and edge detector which is based on neighboring image data distribution, therefore it has some limitation to find accurate salient points after watermark embedding or any kinds of digital attacks. In this paper, we have used cross reference points which use not data distribution but geometrical structure of a normalized image in order to avoid pointing error caused by the distortion of image data. After normalization, we find cross reference points and take inverse normalization of these points. Next, we construct a group of triangles using tessellation with inversely normalized cross reference points. The watermarks are affine transformed and transformed-watermarks are embedded into not normalized image but original one. Only locations of watermarks are determined on the normalized image. Therefore, we can reduce data loss of watermark which is caused by inverse normalization. As a result, we can detect watermarks with high correlation after several digital attacks.

• 대한의용생체공학회:의공학회지
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• 제3권1호
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• pp.49-50
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• 1982

In this paper, the information capacity, the intergrate performance measure of digital radiography system has been quantitatively analyzed. The effect of various factors affecting the information capacity of the digital radiography system in multi-stage detection processes has been considered and analyzed in detail. The results show that the more information capacity can be obtained with the smaller detector cell area, despite of the reduced signal to noise ratio due to the reduced number of X-ray photons per detector cell. Considering the limit of human visual acuity. however, the sufficient resolution will be obtained when the detector cell size in 0.2${\times}$0.2mm with 8 bit quantizaion. And also the results indicates that the information capacity may be severely reduced by the mixture of electric noise in final read-out stage.

• 한국전자파학회논문지
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• 제13권6호
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• pp.560-565
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• 2002

본 논문에서는 무선광연결에서 사용하는 광검출기의 위치가 신호광의 중심으로부터 이탈되어 발생할 수 있는 검출전압의 변동을 디지털가변저항을 이용하여 안정화한다. 검출전압의 안정화가 가능한 최대이탈거리를 계산하고, 검출전압의 안정화 동작을 실험적으로 확인하였다 이 안정화 방법은 신호광 출력이나 빔 진행방향의 미소한 변화 또는 광검출기의 위치변동으로 인한 검출전압의 불안정을 해소하는 데에 매우 유용하게 이용할 수 있다.

• 대한디지털의료영상학회논문지
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• 제13권1호
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• pp.49-53
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• 2011

Dynamic range on the digital detector can be a representation to the ratio of maximum and minimum of pixel value. Wide dynamic range and post processing ability of the digital detector made difficult to recognize visually to high or low dose images. We were evaluated a change of mean pixel value on the original and processed image, when we controlled the kVp, mA, exposure time on the digital detector. On the kVp of a constant condition, we were acquired an original and processed image by changes of mA, exposure time. According to the thickness of the subject under the same conditions, to determine a relation of pixel value and X-ray intensity, we used an aluminum step wedge. When mA and exposure times were changed under the kVp of a constant condition, the X-ray intensity was decreased by the reduction of the mean pixel value. In addition when kVp was increased in a constant condition of mAs, the mean pixel value was increased according to the increment of the X-ray intensity. Therefore, low kVp, high mA and short exposure time were a way to reduce a patient dose.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.418-421
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• 2003

Today, much terminologies such as noise spectrum, Sharpness, contrast, MTF had been defined for Image quality revaluation of radiation Image. Since development of Xeroradiography In the 1970s, Digital radiation detector that use amorphous selenium was developed. The aim of this research is to analyze physical phenomenon of digital radiation detector that use amorphous selenium. Result of Monte Carlo simulations on amorphous selenium based on physical properties(creation of electron-hole pairs) by induced x-ray are described. From the simulation, intrinsic point spread function(PSF) was found and used to observe modulation transfer function(MTF). We investigated how PSF and MTF changed with various x-ray energy. This result can be used to design digital x-ray detector based on a-Se.

• 전자공학회논문지S
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• 제34S권7호
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• pp.28-38
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• 1997

Previously, we have proposed the M-BECM(Modified-Band Edge Component Maximization), which is a symbol synchronization algorithm based on spectral line method for all-digital high speed digital communications. However, Until now, the characteristics of the timing detector based on the spectral line method including M-BECM was not analyzed, particularly the effect of a timing offset at the optimal convergence pont. In this paper, we analyze the timing dtector's characteristics of the M-BECM and present optimal design value. First, the expression for the timing detector's mean value(often called its S-Curver) as a function of the normalized symbol timing offset is derived. Next, the P $D_{bias}$, the value for compensating the timing offset at an optimal convergence point, and the bandwidth of bandpass filter in the timing detector are calculated. It is also shown and analyzed that the P $D_{bias}$ is affected by varuous factors such as the excess bandwidth of input signal, frequency offsets, noise and particularly, the excess bandwidth of input signal is a major parameter to decide P $D_{bias}$. Finally, analytic resutls are compared to simulation results.

• Nuclear Engineering and Technology
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• 제55권3호
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• pp.1009-1014
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• 2023

Muon tomography is a useful method for monitoring special nuclear materials (SNMs) such as spent nuclear fuel inside dry cask storage. Multiple Coulomb scattering of muons can be used to provide information about the 3-dimensional structure and atomic number(Z) of the inner materials. Tomography using muons is less affected by the shielding material and less harmful to health than other measurement methods. We developed a muon detector for muon tomography, which consists of a plastic scintillator, 64 long wavelength-shifting (WLS) fibers attached to the top of the plastic scintillator, and silicon photomultipliers (SiPMs) connected to both ends of each WLS fiber. The muon detector can acquire X and Y positions simultaneously using a position determination algorithm. The design parameters of the muon detector were optimized using DETECT2000 and Geant4 simulations, and a muon detector prototype was built based on the results. Spatial resolution measurement was performed using simulations and experiments to evaluate the feasibility of the muon detector. The experimental results were in good agreement with the simulation results. The muon detector has been confirmed for use in a muon tomography system.

• 전기전자학회논문지
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• 제13권1호
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• pp.77-86
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• 2009

본 논문에서 이식형 심장 박동 조율기를 위한 심전도 검출기와 아날로그-디지털 변환기(ADC)를 설계한다. 제안한 웨이블렛 심전도 검출기는 웨이블렛 필터 뱅크 구조의 웨이블렛 변조기, 웨이블렛 합성된 심전도 신호의 가설 검정을 통한 QRS 신호 검출기와 0-교차점을 이용한 잡음 검출기로 구성된다. 저전력 소모의 동작을 유지하며 보다 높은 검출 정확도를 갖는 심전도 검출기의 구현을 위해, 다중스케일 곱의 알고리즘과 적응형의 임계값을 갖는 알고리즘을 사용하였다. 또한 심전도 검출기의 입력단에 위치하는 저전력 Successive Approximation Register ADC의 구현을 위해, 신호 변환의 주기 중, 매우 짧은 시간 동안에만 동작하는 비교기와 수동 소자로 구성되는 Sample&Hold를 사용하였다. 제안한 회로는 표준 CMOS $0.35{\mu}m$ 공정을 사용하여 집적 및 제작되었고, 99.32%의 높은 검출 정확도와 3V의 전원 전압에서 $19.02{\mu}W$의 매우 낮은 전력 소모를 갖는 것을 실험을 통해 확인하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.390-392
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• 2005

The digital radiation detectors are used clinically by diagnostic apparatus. However the digital radiation detector are some problem like high operating voltage, light blurring, low conversion efficiency, low fill factor, etc. Thus we propose a new radiation detector that the photoconductor layer and liquid crystal layer are coupled in sandwich structure. X-ray absorption in the photoconductor layer controls the state of the liquid crystal via creation of charge carrier and the light modulation of liquid crystal make image formation. The advantage of the new radiation detector is that high resolution image is acquired and the signal amplification is possible by external visible light source. In this study, we study the optical properties and electrical properties of the new radiation detector to irradiate X-ray. The Mercury Iodide($HgI_2$) was used by photoconductor material, and the aluminum is used by reflective layer. The thickness of Mercury Iodide is about $200{\mu}m$, the operating voltage of the liquid crystal is 1.5~5V. The electrical properties of Mercury Iodide was measured, and the transmission efficiency of liquid crystal was measured by modulation potential.