• Title/Summary/Keyword: Threshold Value

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The investigation of pH threshold value on the corrosion of steel reinforcement in concrete

  • Pu, Qi;Yao, Yan;Wang, Ling;Shi, Xingxiang;Luo, Jingjing;Xie, Yifei
    • Computers and Concrete
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    • v.19 no.3
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    • pp.257-262
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    • 2017
  • The aim of this study is to investigate the pH threshold value for the corrosion of steel reinforcement in concrete. A method was designed to attain the pH value of the pore solution on the location of the steel in concrete. Then the pH values of the pore solution on the location of steel in concrete were changed by exposing the samples to the environment (CO25%, RH 40%) to accelerate carbonation with different periods. Based on this, the pH threshold value for the corrosion of steel reinforcement had been examined by the methods of half-cell potential and electrochemical impedance spectra (EIS). The results have indicated that the pH threshold value for the initial corrosion of steel reinforcement in concrete was 11.21. However, in the carbonated concrete, agreement among whether steel corrosion was initiatory determined by the detection methods mentioned above could be found.

Surface Classification and Its Threshold Value Selection for the Recognition of 3-D Objects (3차원 물체 인식을 위한 표면 분류 및 임계치의 선정)

  • 조동욱;백승재;김동원
    • The Journal of the Acoustical Society of Korea
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    • v.19 no.3
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    • pp.20-25
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    • 2000
  • This paper proposes the method of surface classification and threshold value selection for surface classification of the three-dimensional object recognition. The processings of three-dimensional image processing system consist of three steps, i.e, acquisition of range data, feature extraction and matching process. This paper proposes the method of shape feature extraction from the acquired rage data in the entire three-dimensional image processing system. In order to achieve these goals, firstly, this article proposes the surface classification method by using the distribution characteristics of sign value from range values. Also pre-existing method which uses the K-curvature and K-curvature has limitation in the practical threshold value selection. To overcome this, this article proposes the selection of threshold value for surface classification. Finally, the effectiveness of this article is demonstrated by the several experiments.

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Scene Change Detection using the Automated Threshold Estimation Algorithm

  • Ko Kyong-Cheol;Rhee Yang-Won
    • The Journal of Information Systems
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    • v.14 no.3
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    • pp.117-122
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    • 2005
  • This paper presents a method for detecting scene changes in video sequences, in which the $chi^{2}$-test is modified by imposing weights according to NTSC standard. To automatically determine threshold values for scene change detection, the proposed method utilizes the frame differences that are obtained by the weighted $chi^{2}$-test. In the first step, the mean and the standard deviation of the difference values are calculated, and then, we subtract the mean difference value from each difference value. In the next step, the same process is performed on the remained difference values, mean-subtracted frame differences, until the stopping criterion is satisfied. Finally, the threshold value for scene change detection is determined by the proposed automatic threshold estimation algorithm. The proposed method is tested on various video sources and, in the experimental results, it is shown that the proposed method is reliably estimates the thresholds and detects scene changes.

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An Analysis of False Alarm Threshold Value by Heat Detector Using Heat Release Rate (열방출률을 이용한 열감지기의 오동작 경계값 분석)

  • 홍성호;김두현
    • Fire Science and Engineering
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    • v.17 no.3
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    • pp.26-30
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    • 2003
  • This paper presents a study on the analysis for false alarm of heat detector using HRR(Heat Release Rate). And it is represented to threshold value and domain of false alarm. The HRR threshold value of false alarm is calculated to use parameters obtained by small scale fire-experiment. The experiment is conducted to measure detector activation time and flame spread of wood cribs fire, etc. The results show that HRR threshold value of Fixed type detector is 20.24 kW and rate of rise type detector is 13.59 kW, respectively.

An Analysis of Partial Discharge by the Optimum Method of Threshold Value (기준치(Threshold Value) 최적화 기법을 이용한 부분방전 해석)

  • Choi, I.H.;Yun, J.W.;Kweon, D.J.;Jung, G.J.
    • Proceedings of the KIEE Conference
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    • 1999.07e
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    • pp.2277-2279
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    • 1999
  • We have investigated the characteristic analysis of ultrasonic in case of occurring partial discharge in experimental steel chamber. This study presents the discriminative method of partial discharge by optimum threshold value. We have carried out the experiments of measuring partial discharge numbers between ultrasonic sensor and transducer with changing distance and barrier inside steel chamber. After the measured data were trasformed A/D conversion by GPIB, we used the optimum method of threshold value for counting numbers of partial discharge.

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Analysis on Optimal Threshold Value for Infrared Video Flame Detection (적외선 영상의 화염 검출을 위한 최적 문턱치 분석)

  • Jeong, Soo-Young;Kim, Won-Ho
    • Journal of Satellite, Information and Communications
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    • v.8 no.4
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    • pp.100-104
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    • 2013
  • In this paper, we present an optimal threshold setting method for flame detection of infrared thermal image. Conventional infrared flame detection methods used fixed intensity threshold to segment candidate flame regions and further processing is performed to decide correct flame detection. So flame region segmentation step using the threshold is important processing for fire detection algorithm. The threshold should be change in input image depends on camera types and operation conditions. We have analyzed the conventional thresholds composed of fixed-intensity, average, standard deviation, maximum value. Finally, we extracted that the optimal threshold value is more than summation of average and standard deviation, and less than maximum value. it will be enhance flame detection rate than conventional fixed-threshold method.

Performance Indicator and Threshold Value of National Highway Jointed Concrete Pavements (일반국도 줄눈 콘크리트 포장의 성능인자와 임계한도)

  • Yeo, Hyun Dong;Seo, Youngguk;Suh, Young Chan;Jeong, Jin Hoon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.30 no.3D
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    • pp.279-288
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    • 2010
  • Recently, researches on the performance warranty contracting has been going on to improve construction quality in road pavement area. The performance warranty contracting gives construction companies opportunity to select materials and methods freely while asks them to maintain a certain level of performance during a given period. To introduce the performance warranty contracting in Korea, lots of research results on performance indicator and threshold value of asphalt pavement have been made to be included in the warranty specification. However, research effort on the performance indicator and threshold value of concrete pavement which is commonly constructed in expressway and national highway has not been enough. In this study, the warranty duration, performance indicator, and threshold value of the concrete pavement were investigated by reviewing literatures on cases of the performance warranty contracting in European countries and states of the US. Major distresses influencing the performance of jointed concrete pavement were investigated and analyzed to be compared to the warranty duration, performance indicator, and threshold value of foreign countries.

Low Complexity Image Thresholding Based on Block Type Classification for Implementation of the Low Power Feature Extraction Algorithm (저전력 특징추출 알고리즘의 구현을 위한 블록 유형 분류 기반 낮은 복잡도를 갖는 영상 이진화)

  • Lee, Juseong;An, Ho-Myoung;Kim, Byungcheul
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.12 no.3
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    • pp.179-185
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    • 2019
  • This paper proposes a block-type classification based image binarization for the implementation of the low-power feature extraction algorithm. The proposed method can be implemented with threshold value re-use technique approach when the image divided into $64{\times}64$ macro blocks size and calculating the threshold value for each block type only once. The algorithm is validated based on quantitative results that only a threshold value change rate of up to 9% occurs within the same image/block type. Existing algorithms should compute the threshold value for 64 blocks when the macro block is divided by $64{\times}64$ on the basis of $512{\times}512$ images, but all suggestions can be made only once for best cases where the same block type is printed, and for the remaining 63 blocks, the adaptive threshold calculation can be reduced by only performing a block type classification process. The threshold calculation operation is performed five times when all block types occur, and only the block type separation process can be performed for the remaining 59 blocks, so 93% adaptive threshold calculation operation can be reduced.

Influence of threshold value of computed tomography on the accuracy of 3-dimensional medical model (전산화단층 촬영상의 임계치가 3차원 의학모델 정확도에 미치는 영향에 대한 연구)

  • Lee Byeong-Do;Lee Wan
    • Imaging Science in Dentistry
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    • v.32 no.1
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    • pp.27-33
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    • 2002
  • Purpose: To evaluate the influence of threshold value of computed tomography on the accuracy of rapid prototyping (RP) medical model Material and Methods : CT datas of a human dry skull were transferred from CT scanner via compact disk to a personal computer (PC). 3-dimensional image reconstruction on PC by V-works/sup TM/ 3.0 (CyberMed. Inc.) software and RP models fabrication were followed. 2-RP models were produced by threshold value of 500 and 800 selected in surface rendering process. Linear measurements between arbitrary 12 anatomical landmarks on dry skull, 3-D image model, and 2-RP models were done and compared. Thus, the accuracy of 500 RP and 800RP models was respectively evaluated. Results: There was mean difference (% difference) in absolute value of 2.27 mm (2.73%) between linear measurements of dry skull and 500 RP model. There was mean difference (% difference) in absolute value of 1.94 mm (2.52%) between linear measurements of dry skull and 800 RP model. Conclusion: Slight difference of threshold value in rendering process of 3-D modelling made a influence on the accuracy of RP medical model.

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Market effects analysis of when lowering the threshold value of construction services under WTO GPA (WTO 정부조달협정 건설서비스 양허하한선 인하시의 건설시장 변화와 대응방안)

  • Moon, Hyuk;Kim, Myeong-Soo
    • Korean Journal of Construction Engineering and Management
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    • v.10 no.3
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    • pp.72-82
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    • 2009
  • Lowering threshold value of construction services is extremely sensitive issue to the small and medium enterprises in construction industry. Because it means opening the construction markets where the small and medium construction companies compete intensely. Nevertheless, it is absent that the analysis on the effect of opening the market lowering threshold value of construction services under Government Procurement Agreements or Free Trade Agreement. This research is to analyze the effects of lowering threshold value of construction service which have been agenda repeatedly in the international agreements such as WTO and FTA. The current threshold value of construction services of Korea under WTO GPA are 5million SDR where the government delivers and 15million SDR where the local government or the public institution deliver. However major parties to an entente such as USA and EU have been demanding to lower threshold value of 15 million SDR where the local government or the public institution deliver to 5million SDR. The analysis figure the effect of this lowering threshold value to be a market reduction by 2trillion Won as '07 fiscal year basis. This market shrinkage will effect to the small and medium construction companies in local considerably.