• Title/Summary/Keyword: subtraction

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Monte Carlo simulations for gamma-ray spectroscopy using bismuth nanoparticle-containing plastic scintillators with spectral subtraction

  • Taeseob Lim ;Siwon Song ;Seunghyeon Kim ;Jae Hyung Park ;Jinhong Kim;Cheol Ho Pyeon;Bongsoo Lee
    • Nuclear Engineering and Technology
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    • v.55 no.9
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    • pp.3401-3408
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    • 2023
  • In this study, we used the Monte Carlo N-Particle program to simulate the gamma-ray spectra obtained from plastic scintillators holes filled with bismuth nanoparticles. We confirmed that the incorporation of bismuth nanoparticles into a plastic scintillator enhances its performance for gamma-ray spectroscopy using the subtraction method. The subtracted energy spectra obtained from the bismuth-nanoparticle-incorporated and the original plastic scintillator exhibit a distinct energy peak that does not appear in the corresponding original spectra. We varied the diameter and depth of the bismuth-filled holes to determine the optimal hole design for gamma-ray spectroscopy using the subtraction method. We evaluated the energy resolutions of the energy peaks in the gamma-ray spectra to estimate the effects of the bismuth nanoparticles and determine their optimum volume in the plastic scintillator. In addition, we calculated the peak-to-total ratio of the energy spectrum to evaluate the energy measuring limit of the bismuth nanoparticle-containing plastic scintillator using the subtraction method.

Block-matching and 3D filtering algorithm in X-ray image with photon counting detector using the improved K-edge subtraction method

  • Kyuseok Kim;Youngjin Lee
    • Nuclear Engineering and Technology
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    • v.56 no.6
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    • pp.2057-2062
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    • 2024
  • Among photon counting detector (PCD)-based technologies, the K-edge subtraction (KES) method has a very high material decomposition efficiency. Yet, since the increase in noise in the X-ray image to which the KES method is applied is inevitable, research on image quality improvement is essential. Here, we modeled a block-matching and 3D filtering (BM3D) algorithm and applied it to PCD-based X-ray images with the improved KES (IKES) method. For PCD modeling, Monte Carlo simulation was used, and a phantom composed of iodine substances with different concentrations was designed. The IKES method was modeled by adding a log term to KES, and the X-ray image used for subtraction was obtained by applying the 3.0 keV range based on the K-edge region of iodine. As a result, the IKES image using the BM3D algorithm showed the lowest normalized noise power spectrum value. In addition, we confirmed that the contrast-to-noise ratio and no-reference-based evaluation results when the BM3D algorithm was applied to the IKES image were improved by 29.36 % and 20.56 %, respectively, compared to the noisy image. In conclusion, we demonstrated that the IKES imaging technique using a PCD-based detector and the BM3D algorithm fusion technique were very efficient for X-ray imaging.

An Analysis on the Problem Solving of Korean and American 3rd Grade Students in the Addition and Subtraction with Natural Numbers (한국과 미국 초등학교 3학년 학생들의 자연수 덧셈과 뺄셈 문제해결 분석)

  • Lee, Dae Hyun
    • Education of Primary School Mathematics
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    • v.19 no.3
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    • pp.177-191
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    • 2016
  • Students can calculate the addition and subtraction problem using informal knowledge before receiving the formal instruction. Recently, the value that a computation lesson focus on the understanding and developing the various strategies is highlighted by curriculum developers as well as in reports. Ideally, a educational setting and classroom culture reflected students' learning and problem solving strategies. So, this paper analyzed the similarity and difference with respect to the numeric sentence and word problem in the addition and subtraction. The subjects for the study were 100 third-grade Korean students and 68 third-grade American students. Researcher developed the questionnaire in the addition and subtraction and used it for the survey. The following results have been drawn from this study. The computational ability of Korean students was higher than that of American students in both the numeric sentence and word problem. And it was revealed the differences of the strategies which were used problem solving process. Korean students tended to use algorithms and numbers' characters and relations, but American students tended to use the drawings and algorithms with drawings.

An Improved Adaptive Background Mixture Model for Real-time Object Tracking based on Background Subtraction (배경 분리 기반의 실시간 객체 추적을 위한 개선된 적응적 배경 혼합 모델)

  • Kim Young-Ju
    • Journal of the Korea Society of Computer and Information
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    • v.10 no.6 s.38
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    • pp.187-194
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    • 2005
  • The background subtraction method is mainly used for the real-time extraction and tracking of moving objects from image sequences. In the outdoor environment, there are many changeable environment factors such as gradually changing illumination, swaying trees and suddenly moving objects , which are to be considered for an adaptive processing. Normally, GMM(Gaussian Mixture Model) is used to subtract the background by considering adaptively the various changes in the scenes, and the adaptive GMMs improving the real-time Performance were Proposed and worked. This paper, for on-line background subtraction, employed the improved adaptive GMM, which uses the small constant for learning rate a and is not able to speedily adapt the suddenly movement of objects, So, this paper Proposed and evaluated the dynamic control method of a using the adaptive selection of the number of component distributions and the global variances of pixel values.

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New Speech Enhancement Method using Psychoacoustic Criteria (심리 음향 기준을 이용한 새로운 음질 개선 방법)

  • 김대경;박장식;손경식
    • Journal of Korea Multimedia Society
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    • v.4 no.1
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    • pp.56-66
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    • 2001
  • The spectral subtraction algorithm using a criterion based on the human perception has been recently developed. The speech processed with Virag's algorithm sounds more pleasant to a human listener than those obtained by the classical methods. However, Virag's algorithm requires a robust voice activity detector (VAD). In the ESS (extended spectral subtraction) algorithm without VAD, the residual noise becomes more noticeable as the SNR decrease. In this paper we propose a new speech enhancement method, the combination of Wiener filter and spectral subtraction based on noise masking characteristics in the human auditory system. There is no need of VAD because the noise can be successively updated even during speech activity using Wiener filter. The adjustment of the subtraction parameter based on the masking threshold makes the residual noise inaudible. The proposed method has been compared with conventional spectral subtraction algorithms. Objective and subjective evaluation of the proposed system is performed with several noise types having different time-frequency distributions. The application of objective measures, the study of the speech spectrograms, as well as subjective listening tests, confirm that the enhanced speech with proposed algorithm is more pleasant to a human listener.

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A Study on Non-Subtraction and Subtraction Technique in 3-Dimensional Angiography of the Cerebral Aneurysm (뇌동맥자루 3차원 혈관조영술에서 비감산 및 감산 기법에 관한 연구)

  • Kim, Kyung-Wan;Im, In-Chul;Lee, Hyo-Yeong
    • Journal of the Korean Society of Radiology
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    • v.12 no.4
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    • pp.511-518
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    • 2018
  • The purpose of this study was to measured the diameter, maximum diameter, maximum area and volume of the cerebral aneurysm in 53 patients who underwent three-dimensional digital angiography and three-dimensional digital subtraction angiography, which were used for the clinical diagnosis of cerebral aneurysm, image noise and radiation exposure dose of each test method were analyzed to compare clinical diagnosis differences in the cerebral aneurysm diagnosis. Three-dimensional digital angiography and three-dimensional digital subtraction angiography showed that the neck diameter, maximum diameter, maximum area, volume, and noise of the cerebral aneurysm were identical or very small. However, the three-dimensional digital angiography significantly decreased the radiation exposure dose compared to three-dimensional digital subtraction angiography. Therefore, in case of clinical diagnosis of cerebral aneurysm, three-dimensional digital angiography should be preferentially used to reduce radiation exposure dose of patient.

Accuracy of Live Fluoroscopy to Detect Intravascular Injection During Lumbar Transforaminal Epidural Injections

  • Lee, Min-Hye;Yang, Kyung-Seung;Kim, Young-Hoon;Jung, Hyun-Do;Lim, Su-Jin;Moon, Dong-Eon
    • The Korean Journal of Pain
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    • v.23 no.1
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    • pp.18-23
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    • 2010
  • Background: Complications following lumbar transforaminal epidural injection are frequently related to inadvertent vascular injection of corticosteroids. Several methods have been proposed to reduce the risk of vascular injection. The generally accepted technique during epidural steroid injection is intermittent fluoroscopy. In fact, this technique may miss vascular uptake due to rapid washout. Because of the fleeting appearance of vascular contrast patterns, live fluoroscopy is recommended during contrast injection. However, when vascular contrast patterns are overlapped by expected epidural patterns, it is hard to distinguish them even on live fluoroscopy. Methods: During 87 lumbar transforaminal epidural injections, dynamic contrast flows were observed under live fluoroscopy with using digital subtraction enhancement. Two dynamic fluoroscopy fluoroscopic images were saved from each injection. These injections were performed by five physicians with experience independently. Accuracy of live fluoroscopy was determined by comparing the interpretation of the digital subtraction fluoroscopic images. Results: Using digital subtraction guidance with contrast confirmation, the twenty cases of intravascular injection were found (the rate of incidence was 23%). There was no significant difference in incidence of intravascular injections based either on gender or diagnosis. Only five cases of intravascular injections were predicted with either flash or aspiration of blood (sensitivity = 25%). Under live fluoroscopic guidance with contrast confirmation to predict intravascular injection, twelve cases were predicted (sensitivity = 60%). Conclusions: This finding demonstrate that digital subtraction fluoroscopic imaging is superior to blood aspiration or live fluoroscopy in detecting intravascular injections with lumbar transforaminal epidural injection.

Noise Reduction using Spectral Subtraction in the Discrete Wavelet Transform Domain (이산 웨이브렛 변환영역에서의 스펙트럼 차감법을 이용한 잡음제거)

  • 김현기;이상운;홍재근
    • Journal of Korea Multimedia Society
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    • v.4 no.4
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    • pp.306-315
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    • 2001
  • In noise reduction method from noisy speech for speech recognition in noisy environments, conventional spectral subtraction method has a disadvantage which distinction of noise and speech is difficult, and characteristic of noise can't be estimated accurately. Also, noise reduction method in the wavelet transform domain has a disadvantage which loss of signal is generated in the high frequency domain. In order to compensate theme disadvantage, this paper propose spectral subtraction method in continuous wavelet transform domain which speech and non- speech intervals is distinguished by standard deviation of wavelet coefficient, and signal is divided three scales at different scale. The proposed method extract accurately characteristic of noise in order to apply spectral subtraction method by end detection and band division. The proposed method shows better performance than noise reduction method using conventional spectral subtraction and wavelet transform from viewpoint signal to noise ratio and Itakura-Saito distance by experimental.

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Flexible Background-Texture Analysis for Coronary Artery Extraction Based on Digital Subtraction Angiography (유동적인 배경 텍스쳐 분석을 통한 DSA 기반의 관상동맥 검출)

  • Park Sung-Ho;Lee Joong-Jae;Lee Geun-Soo;Kim Gye-Young
    • The KIPS Transactions:PartB
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    • v.12B no.5 s.101
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    • pp.543-552
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    • 2005
  • This paper proposes the extraction of coronary arteries based on DSA(Digital Subtraction Angiography) through a texture analysis of background in the angiography. DSA is a well established modality for the visualization of coronary arteries. DSA involves the subtraction of a mask image - an image of the heart before injection of contrast medium - from live image. However, this technique is sensitive to the movement of background and can result to a wrong detection by the variance of background gray-level intensity between two images. Therefore, this paper solves a structural problem resulted from a background movement bV selecting an image which has the least difference of movement through an analysis of the similarity of background texture and proposes a method to extract only the blood vessel efficiently through local gray-level correction of the selected image. Using the coronary angiogram of 5 patients clinical data, we proved that the proposed method has the lower false-detection rate, approximately $2\%$, and the higher accuracy than the existing methods.

Dynamic Control of Learning Rate in the Improved Adaptive Gaussian Mixture Model for Background Subtraction (배경분리를 위한 개선된 적응적 가우시안 혼합모델에서의 동적 학습률 제어)

  • Kim, Young-Ju
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • v.9 no.2
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    • pp.366-369
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    • 2005
  • Background subtraction is mainly used for the real-time extraction and tracking of moving objects from image sequences. In the outdoor environment, there are many changeable factor such as gradually changing illumination, swaying trees and suddenly moving objects, which are to be considered for the adaptive processing. Normally, GMM(Gaussian Mixture Model) is used to subtract the background adaptively considering the various changes in the scenes, and the adaptive GMMs improving the real-time performance were worked. This paper, for on-line background subtraction, applied the improved adaptive GMM, which uses the small constant for learning rate ${\alpha}$ and is not able to speedily adapt the suddenly movement of objects, So, this paper proposed and evaluated the dynamic control method of ${\alpha}$ using the adaptive selection of the number of component distributions and the global variances of pixel values.

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