• Title/Summary/Keyword: Decision Threshold

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The difference of Quantitative Analysis According to the Method of Region of Interest Setting in $^{99m}Tc$-DMSA Renal Scan ($^{99m}Tc$-DMSA 신장 검사에서 ROI 설정 방법에 따른 정량분석 차이에 관한 연구)

  • Lee, Jong-Hun;Shim, Dong-Oh
    • The Korean Journal of Nuclear Medicine Technology
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    • v.14 no.1
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    • pp.73-77
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    • 2010
  • Purpose: The nuclear medicine technology has been changed. The hard ware is developed so much. Also the soft ware performs a meritorious deed for the development of nuclear medicine technology. We could use the automated region of interest (ROI) instead of manual ROI. We want to know that what difference of quantitative analysis is there between automated ROI and manual ROI Materials and Methods: There are three experimental to make results. The first is what comparing the renal automated ROI and manual ROI. The second is that we compared three threshold ROI that size is difference each others with visible decision. The third is that we compared full, half, quarter automated background, and survey relative function. Results: Although the first has statistically not significant difference, the second and third have significant difference. Threshold, setting smaller threshold then renal outline or bigger, has statistically significant difference (p<0.01). The third is performed with the first experimental. Full background has significant difference, comparing each three type background (p<0.05). Conclusion: The results that there is not significant difference between automated ROI and manual ROI will increase objectivity and operator's convenience. We could know that smaller threshold then renal out line has significant difference in the second experimental. And the third experimental has results because of a increased background nearby live and spleen.

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Analysis and Optimization of Cooperative Spectrum Sensing with Noisy Decision Transmission

  • Liu, Quan;Gao, Jun;Guo, Yunwei;Liu, Siyang
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.5 no.4
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    • pp.649-664
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    • 2011
  • Cooperative spectrum sensing (CSS) with decision fusion is considered as a key technology for tackling the challenges caused by fading/shadowing effects and noise uncertainty in spectrum sensing in cognitive radio. However, most existing solutions assume an error-free decision transmission, which is obviously not the case in realistic scenarios. This paper extends the general decision-fusion-based CSS scheme by considering the fading/shadowing effects and noise corruption in the common control channels. With this more practical model, the fusion centre first estimates the local decisions using a binary minimum error probability detector, and then combines them to get the final result. Theoretical analysis and simulation of this CSS scheme are performed over typical channels, which suggest some performance deterioration compared with the pure case that assumes an error-free decision transmission. Furthermore, the fusion strategy optimization in the proposed cooperation model is also investigated using the Bayesian criteria. The numerical results show that the total error rate of noisy CSS is higher than that of the pure case, and the optimal values of fusion parameter in the counting rule under both cases decrease as the local detection threshold increases.

A Block-based Motion Detection Algorithm with Adaptive Thresholds for Digital Video Surveillance Systems (적응적으로 임계값을 결정하는 블럭 기반의 디지털 감시 시스템용 움직임 검출 알고리즘)

  • Yang, Yun-Seok;Lee, Dong-Ho
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.37 no.5
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    • pp.31-41
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    • 2000
  • This paper proposes a block-based motion detection algorithm for digital video surveillance system which adaptively decides the threshold according to the kinds of images We first compute the features of a block after dividing each Image into small sub-block regions, and analyze performance of the motion detection algorithm based on statistic features by using the proposed threshold-decision method. Motion vectors are used to analyze motion degree and adaptively determine the threshold The simulation results show the performances of motion detection algorithms according to sub-block size, statistic features, noise, and threshold.

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The Decision Method of A Threshold in Sequence-based Anomaly Detection Sensor (순서기반 비정상행위 탐지 센서의 임계치 결정 방법)

  • Kim, Yong-Min;Kim, Min-Su;Kim, Hong-Geun;No, Bong-Nam
    • The KIPS Transactions:PartC
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    • v.8C no.5
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    • pp.507-516
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    • 2001
  • In this paper, we implement sequence-based anomaly detection sensor using SOM and HMM, and analyze what is important information in system call and how a threshold is decided. The new filtering and reduction rules of SOM reduces the input size of HMM. This gives real-time processing to HMM-based anomaly detection sensor. Also, we introduced an anomaly count into the sensor. Due to lessened sensibility, a user easily understand easily the detection information and false-positive was decreased. And the active coordination of the threshold value makes the detection sensor adapt according to the system condition.

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A Selectively Cumulative Sum(S-CUSUM) Control Chart (선택적 누적합(S-CUSUM) 관리도)

  • Lim, Tae-Jin
    • Journal of Korean Society for Quality Management
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    • v.33 no.3
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    • pp.126-134
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    • 2005
  • This paper proposes a selectively cumulative sum(S-CUSUM) control chart for detecting shifts in the process mean. The basic idea of the S-CUSUM chart is to accumulate previous samples selectively in order to increase the sensitivity. The S-CUSUM chart employs a threshold limit to determine whether to accumulate previous samples or not. Consecutive samples with control statistics out of the threshold limit are to be accumulated to calculate a standardized control statistic. If the control statistic falls within the threshold limit, only the next sample is to be used. During the whole sampling process, the S-CUSUM chart produces an 'out-of-control' signal either when any control statistic falls outside the control limit or when L -consecutive control statistics fall outside the threshold limit. The number L is a decision variable and is called a 'control length'. A Markov chain approach is employed to describe the S-CUSUM sampling process. Formulae for the steady state probabilities and the Average Run Length(ARL) during an in-control state are derived in closed forms. Some properties useful for designing statistical parameters are also derived and a statistical design procedure for the S-CUSUM chart is proposed. Comparative studies show that the proposed S-CUSUM chart is uniformly superior to the CUSUM chart or the Exponentially Weighted Moving Average(EWMA) chart with respect to the ARL performance.

Microcalcification Extraction by Using Automatic Thredholding Based on Region Growing (영역 성장법을 기반으로 자동적인 임계치 설정을 이용한 미세 석회화 추출)

  • 원철호;권용준;이정현;박희준;임성운;김명남;조진호
    • Journal of Biomedical Engineering Research
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    • v.25 no.4
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    • pp.235-242
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    • 2004
  • In this paper, we proposed the algorithm for detection of microtalcification by automatic threshold decision based on region growing method. The region for optimal threshold is grown from local maximum pixel by increasing repeatedly threshold in microralcification candidate region. Then, the optimal threshold is automatically decided at the maximum value of the contrast and edge sharpness in this region. Microcalcifications could be efficiently detected as satisfied result that true positive ratio is 81.5% and average false positive numbers are 1.1 about total 299 microcalcifirations in real image. In a result, we showed that this algorithm can be used to aid diagnostic-radiologist for the diagnosis of the early phase of breast cancer.

An Optimization Method for BAQ(Block Adaptive Quantization) Threshold Table Using Real SAR Raw Data (영상레이다 원시데이터를 이용한 BAQ(Block Adaptive Quantization) 최적화 방법)

  • Lim, Sungjae;Lee, Hyonik;Kim, Seyoung;Nam, Changho
    • Journal of the Korea Institute of Military Science and Technology
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    • v.20 no.2
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    • pp.187-196
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    • 2017
  • The size of raw data has dramatically increased due to the recent trend of Synthetic Aperture Radar(SAR) development plans for high resolution and high definition image acquisition. The large raw data has an impact on satellite operability due to the limitations of storage and transmission capacity. To improve the SAR operability, the SAR raw data shall be compressed before transmission to the ground station. The Block Adaptive Quantization (BAQ) algorithm is one of the data compression algorithm and has been used for a long time in the spaceborne SAR system. In this paper, an optimization method of BAQ threshold table is introduced using real SAR raw data to prevent the degradation of signal quality caused by data compression. In this manner, a new variation estimation strategy and a new threshold method for block type decision are introduced.

An Automatic Contour Detection of 2-D Echocardiograms Using the Heat Anisotropic Diffusion Method (Heat Anisotropic Diffusion 방법을 이용한 2차원 심초음파도에서 경계선 자동 검출)

  • 신동조;김동윤
    • Progress in Medical Physics
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    • v.7 no.2
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    • pp.79-90
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    • 1996
  • In this paper, we present an automatic threshold decision method to detect the contour of the a 2-D echocarodiogram by using the Bayes estimator for the boundary-like region. The boundary-like region is constructed from the conduction coefficient of the heat anisotro-pic diffusion method which enforces the blurred image during the preprocessing step. For the boundary-like region, we used the Bayes estimator to select an optimal threshold level. From this threshold value, the contour of the echocardigrams can be detected automatically Finally by overlapping the estimated contour to the original echocardiogram, we can obtain the contour enforced ultrasound echocardiogram.

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Effects of Multiple Threshold Values for PN Code Acquisition in DS-CDMA Systems (PN 코드 동기획득에서 다중 임계치의 효과)

  • Lee, Seong-Ju;Kim, Jae-Seok
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.39 no.1
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    • pp.42-48
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    • 2002
  • In this paper, a decision method using multiple threshold values for PN code acquisition in Direct Sequence Code Division Multiple Access (DS-CDMA) systems is described. We apply this technique to the conventional double dwell serial search algorithm and analyze it in terms of mean code acquisition time. For the analysis, we present mathematical model of proposed algorithm and also perform the simulation under IMT-2000 channel models. Numerical results show that our proposed scheme outperforms the conventional one by 0.2 - 0.5 sec with respect to the mean code acquisition time because multiple threshold values mitigate the possible decline in search performance caused by the use of a single threshold.