• Title/Summary/Keyword: variable threshold method

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Implementation of Variable Threshold Dual Rate ADPCM Speech CODEC Considering the Background Noise (배경잡음을 고려한 가변임계값 Dual Rate ADPCM 음성 CODEC 구현)

  • Yang, Jae-Seok;Han, Kyong-Ho
    • Proceedings of the KIEE Conference
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    • 2000.07d
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    • pp.3166-3168
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    • 2000
  • This paper proposed variable threshold dual rate ADPCM coding method which is modified from the standard ADPCM of ITU G.726 for speech quality improvement. The speech quality of variable threshold dual rate ADPCM is better than single rate ADPCM at noisy environment without increasing the complexity by using ZCR(Zero Crossing Rate). In this case, ZCR is used to divide input signal samples into two categories(noisy & speech). The samples with higher ZCR is categorized as the noisy region and the samples with lower ZCR is categorized as the speech region. Noisy region uses higher threshold value to be compressed by 16Kbps for reduced bit rates and the speech region uses lower threshold value to be compressed by 40Kbps for improved speech quality. Comparing with the conventional ADPCM, which adapts the fixed coding rate. the proposed variable threshold dual rate ADPCM coding method improves noise character without increasing the bit rate. For real time applications, ZCR calculation was considered as a simple method to obtain the background noise information for preprocess of speech analysis such as FFT and the experiment showed that the simple calculation of ZCR can be used without complexity increase. Dual rate ADPCM can decrease the amount of transferred data efficiently without increasing complexity nor reducing speech quality. Therefore result of this paper can be applied for real-time speech application such as the internet phone or VoIP.

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A Study on Buffer Processing using Push Out Scheme with Variable Threshold (가변 임계값을 갖는 푸쉬 아웃 기법을 이용한 트래픽 제어)

  • 최인수;박호균;류황빈
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.18 no.12
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    • pp.1884-1892
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    • 1993
  • In push out scheme, high priority cell which arrives when the buffer is full pushs low priority cell. The PBS scheme provides priority by variable threshold in buffer.In this paper, for Controlling congestion in ATM network we propose buffer processing method in which the PBS scheme has variable threshold. And we analysis The performance of this scheme. As a result of simulation, the proposed push out scheme with variable threshold reduces the loss of low priority cell compared with existing push out scheme. This proposed method not only reduces the loss of high priority cell like existing push out scheme but also reduces the loss of low priority cell by variable threshold.

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Comparison of Echogram Analysis Methods for Evaluating the Sound-scattering Layer (음향산란층의 식별을 위한 에코그램 분석 방법의 비교)

  • Choi, Seok-Gwan;Yoon, Eun-A;Han, Inwoo;Oh, Wooseok
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.49 no.6
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    • pp.856-861
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    • 2016
  • This study compared the density of fish determined using three different echogram methods: the frequency-difference, time variable, and threshold modification methods. An acoustic survey was conducted off the coast of Jeju Island after sunset. Data at 38 and 120 kHz frequencies were collected using a commercial fishing vessel. As a reference point, the value of ${\Delta}MVBS_{120-38kHz}$ that distinguished fish from zooplankton using the 38 and 120 kHz frequencies was set at < 2 dB. The estimated density of fish along the survey line was 0.1-30.4, 0.1-64.3, and $0.1-51.7m^2/nmi^2$ using the frequency difference, time variable threshold, and threshold modification methods, respectively. The results of this study constitute basic research for estimating fish densities.

An Application of the Clustering Threshold Gradient Descent Regularization Method for Selecting Genes in Predicting the Survival Time of Lung Carcinomas

  • Lee, Seung-Yeoun;Kim, Young-Chul
    • Genomics & Informatics
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    • v.5 no.3
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    • pp.95-101
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    • 2007
  • In this paper, we consider the variable selection methods in the Cox model when a large number of gene expression levels are involved with survival time. Deciding which genes are associated with survival time has been a challenging problem because of the large number of genes and relatively small sample size (n<

Variable Dynamic Threshold Method for Video Cut Detection (동영상 컷 검출을 위한 가변형 동적 임계값 기법)

  • 염성주;김우생
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.27 no.4A
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    • pp.356-363
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    • 2002
  • Video scene segmentation is fundamental role for content based video analysis and many kinds of scene segmentation schemes have been proposed in previous researches. However, there is a problem, which is to find optimal threshold value according to various kinds of movies and its content because only fixed single threshold value usually used for cut detection. In this paper, we proposed the variable dynamic threshold method, which change the threshold value by a probability distribution of cut detection interval and information of frame feature differences and cut detection interval in previous cut detection is used to determine the next cut detection. For this, we present a cut detection algorithm and a parameter generation method to change the threshold value in runtime. We also show the proposed method, which can minimize fault alarm rate than the existing methods efficiently by experimental results.

ANALYSIS OF AN MMPP/G/1/K FINITE QUEUE WITH TWO-LEVEL THRESHOLD OVERLOAD CONTROL

  • Lee, Eye-Min;Jeon, Jong-Woo
    • Communications of the Korean Mathematical Society
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    • v.14 no.4
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    • pp.805-814
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    • 1999
  • We consider an MMPP/G/1/K finite queue with two-level threshold overload control. This model has frequently arisen in the design of the integrated communication systems which support a wide range applications having various Quality of Service(QoS) requirements. Through the supplementary variable method, se derive the queue length distribution.

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JPEG Image Quantization Method with Variable Thresholds (가변 임계값을 갖는 JPEG 영상의 양자화 방법)

  • 윤석현
    • Journal of the Korea Society of Computer and Information
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    • v.8 no.2
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    • pp.24-30
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    • 2003
  • In this Paper VTQM(Variable Threshold quantization Method) is proposed, which enhances PSNR by composing the advantages of round-off and truncation quantization methods. From vast experiments, PSNR's of JPEG images with the method are compared with that of standard JPEG methods. At the boundary which affects the compression ratio, VTQM quantizes with a new threshold to reduce the length of compressed data; otherwise, VTQM employs the round-off quantization method to preserve the original image information. As a result, VTQM reduces bit rate while preserving the image quality. The experimental results show that VTQM enhances PSNR by 0.2∼0.3dB, 0.4∼0.5dB with the same bit rate than those of the traditional truncation and round-off quantization methods, respectively.

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JPEG Image Quantization Method with Variable Thresholds (가변 임계값을 갖는 JPEG 영상의 양자화 방법)

  • O, Ha-Ryeong;Yun, Seok-Hyeon;Seong, Yeong-Rak
    • The Transactions of the Korea Information Processing Society
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    • v.6 no.11
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    • pp.3150-3156
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    • 1999
  • In this paper, VTQM(Variable Threshold Quantization Method) is proposed, which enhances PSNR by composing the advantages of round-off and truncation quantization methods. From vast experiments, PSNR's of JPEG images with the method are compared with that of standard JPEG methods. At the boundary which affects the compression ratio, VTQM quantizes with a new threshold to reduce the length of compressed data; otherwise, VTQM employs the round-off quantization method to preserve the original image information. As a result, VTQM reduces bit rate while preserving the image quanity. The experimental results show that VTQM enhances PSNR by 0.2-0.3dB., 0.4-0.5dB, with the same bit rate than those of the traditional truncation and round-off quantization methods, respectively.

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Text-Prompt Speaker Verification using Variable Threshold and Sequential Decision (가변 문턱치와 순차결정법을 통한 문맥요구형 화자확인)

  • Ahn, Sung-Joo;Kang, Sun-Mee;Ko, Han-Seok
    • Speech Sciences
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    • v.7 no.4
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    • pp.41-47
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    • 2000
  • This paper concerns an effective text-prompted speaker verification method to increase the performance of speaker verification. While various speaker verification methods have already been developed, their effectiveness has not yet been formally proven in terms of achieving an acceptable performance level. It is also noted that the traditional methods were focused primarily on single, prompted utterance for verification. This paper, instead, proposes sequential decision method using variable threshold focused at handling two utterances for text-prompted speaker verification. Experimental results show that the proposed speaker verification method outperforms that of the speaker verification scheme without using the sequential decision by a factor of up to 3 times. From these results, we show that the proposed method is highly effective and achieves a reliable performance suitable for practical applications.

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Algorithm Development and Experimental Verification of Acoustic Emission First-arrival-time Determination for the Source Location (정확한 미소파괴음의 발생위치 분석을 위한 신호 도달시간 결정 알고리즘 연구 및 실험적 검증)

  • Jang, Hyun-Sic;Choi, Jun-Young;Jang, Bo-An
    • The Journal of Engineering Geology
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    • v.25 no.4
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    • pp.587-598
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    • 2015
  • We examined various existing threshold methods for the determination of the first arrival time of acoustic emission (AE), and developed a new variable threshold method that could determine the first arrival time of AE more accurately and more quickly than existing methods. The new method, a modification of an existing threshold method, does not fix the threshold, but applies variable thresholds for the AE signals according to noise analysis. Two- and three-dimensional models were established to test the effectiveness of the new method. It could determine source locations of AE in a two-dimensional model 38.3% more accurately than the pre-existing threshold methods. Its accuracy improvement over the existing methods in a three-dimensional model was about 15.2%. A practical test involved measuring the source locations of AE during three-point bending tests of granite cores. The new method placed the sources closer to the fracture plane than did the pre-existing methods, indicating its superior (and quicker) ability to determine the source locations of AE.