• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.445-451
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• 2010

This paper presents a threshold adaptation based voice query transcription scheme for music information retrieval. The proposed scheme analyzes monophonic voice signal and generates its transcription for diverse music retrieval applications. For accurate transcription, we propose several advanced features including (i) Energetic Feature eXtractor (EFX) for onset, peak, and transient area detection; (ii) Modified Windowed Average Energy (MWAE) for defining multiple small but coherent windows with local threshold values as offset detector; and finally (iii) Circular Average Magnitude Difference Function (CAMDF) for accurate acquisition of fundamental frequency (F0) of each frame. In order to evaluate the performance of our proposed scheme, we implemented a prototype music transcription system called AMT2 (Automatic Music Transcriber version 2) and carried out various experiments. In the experiment, we used QBSH corpus [1], adapted in MIREX 2006 contest data set. Experimental result shows that our proposed scheme can improve the transcription performance.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.5
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• pp.361-367
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• 2004

This paper describes design of an algorithm for analyzing human activity using body-fixed 3-axis accelerometer in the small of the back. In the first step, we distinguish static and dynamic activity period using AC signal analysis. Then five postures were classified by applying the threshold in DC signal corresponding to the static activity period. Also, after comparison of average power and taking negative peak signal in the dynamic activity period, the four dynamic activities were classified by adaptive threshold method. To evaluate the performance of the proposed algorithm, the measured signals obtained from six subjects were applied to the proposed algorithm and the results were compared with the simultaneously measured video data. As a result, the activity classification rate of 95.7％ on average was obtained. Overall results show that the proposed classification algorithm has a possibility to be used to analyze the static and dynamic physical activity.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.1
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• pp.161-171
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• 2014

When the Hough transform is applied to identify an instance of a given model, the output is typically a histogram of votes cast by a set of image features into a parameter space. The next step is to threshold the histogram of counts to hypothesize a given match. The question is "What is a reasonable choice of the threshold?" In a standard implementation of the Hough transform, the threshold is selected heuristically, e.g., some fraction of the highest cell count. Setting the threshold too low can give rise to a false alarm of a given shape(Type I error). On the other hand, setting the threshold too high can result in mis-detection of a given shape(Type II error). In this paper, we derive two conditional probability functions of cell counts in the accumulator array of the generalized Hough transform(GHough), that can be used to select a scientific threshold at the peak detection stage of the Ghough.

• Journal of Korea Water Resources Association
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• v.35 no.5
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• pp.553-561
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• 2002

The objectives of this study are to introduce flash flood forecasting system in Korea and to develop a system for computing threshold runoff on very fine catchment scale. The developed GUI system composed of 9 steps starting from input data preparation to Input file creation for flash flood forecasting compute basin subdivision, hydrologic subbasin characteristics, bankfull flows, unit peak flows and threshold runoffs on about 5 $\textrm{km}^2$ scale. When the developed system was applied on Pyungchang IHP basin, the computed 1-hour threshold runoffs ranged 18.72~81.96mm with average value of 46.39mm. Judging from the comparison of the computed threshold runoffs between this study area and three other basins in United States, the computed results in this study were reasonable. It can be concluded that the developed system on ArcView/Avenue are useful for computing threshold runoff on small catchment and can be used as a component of flash flood forecasting system.

• Journal of Microbiology and Biotechnology
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• v.11 no.4
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• pp.614-618
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• 2001

Low-threshold T-type $Ca^{2+}$ channels are distinctive voltage-operated gates for external $Ca^{2+}$ entry around a resting membrane potential due to their low voltage activation. These phenomena have already been extensively studied due to their relevance in diverse physiological functions. Recently, three T-type $Ca^{2+}$ channel ${\alpha}$$_1$subunits were cloned and their biophysical properties were characterized after expression in mammalian expression systems. In this study, ${\alpha_IG} and {\alpha_IH}$ low-threshold $Ca^{2+}$ channels were expressed and characterized in Xenopus oocytes after adding 5' and 3'untranslated portions of a Xenopus ${\beta}$ globin to improve their expression levels. The added portions dramatically enhanced the expression levels of the ${\alpha_IG} and {\alpha_IH}$ T-type channels. When currents were recorded in 10 mM $Ba^{2+}$ as the charge carrier, the activation thresholds were about -60 mV, peak currents appeared at -20 mV, and the reversal potentials were between +40 and +45. The activation time constants were very similar to each other, while the inactivation time constants of the ${\alpha_IG}$ currents were smaller than those of ${\alpha_IH}$. Taken together, the electrophysiological properties of the ${\alpha_IG} and {\alpha_IH}$ channels expressed in Xenopus oocytes were similar to the previously reported characteristics of low-threshold $Ca^{2+}$ channel currents.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.4
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• pp.309-313
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• 2000

A experiment was carried out to measure the auditory threshold of dusky spinefoot Siganus fuscescens(Houttuyn) in the coast of Cheju Island by heartbeat conditioning technique using pure tones coupled with a delayed electric shock in order to investigate the hearing ability to audible sound. The audible range of dusky spinefoot extended from 80Hz to 800Mhz with a peak sensitivity at 200Hz. The mean auditory threshold levels of dusky spinefuot were 102dB, 96dB, 92dB, 95dB, 105dB and 121dB respectively in the range of measurement frequencies, As the frequency became higher than 300Hz, the auditory threshold increased rapidly.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.3
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• pp.427-435
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• 1997

Conditional sampling techniques are utilized to investigate the relation between the wall skin-friction and stream wise velocity fluctuations in a turbulent boundary layer. Conditionally averaged results using a peak detection and the VITA (variable-interval time-averaging) technique show that a high skin friction is associated with high frequency components of the wall skin-friction fluctuations. The conditionally averaged wall skin-friction fluctuations obtained by using the VITA technique have a positively-skewed characteristics compared with the conditionally averaged stream wise velocity fluctuations. It is confirmed that there exists a phase shift between the wall skin-friction and stream wise velocity fluctuations, which was also found from the long-time averaged space-time correlations. The amount of phase shift between the wall skin-friction and stream wise velocity fluctuations is the same as that from the long-time averaged space-time correlations and does not change despite the variation of the detection threshold.

• International Journal of Automotive Technology
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• v.8 no.4
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• pp.493-504
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• 2007

This paper proposes a stereo vision-based forward obstacle detection and distance measurement method. In general, stereo vision-based obstacle detection methods in automotive applications can be classified into two categories: IPM (Inverse Perspective Mapping)-based and disparity histogram-based. The existing disparity histogram-based method was developed for stop-and-go applications. The proposed method extends the scope of the disparity histogram-based method to highway applications by 1) replacing the fixed rectangular ROI (Region Of Interest) with the traveling lane-based ROI, and 2) replacing the peak detection with a constant threshold with peak detection using the threshold-line and peakness evaluation. In order to increase the true positive rate while decreasing the false positive rate, multiple candidate peaks were generated and then verified by the edge feature correlation method. By testing the proposed method with images captured on the highway, it was shown that the proposed method was able to overcome problems in previous implementations while being applied successfully to highway collision warning/avoidance conditions, In addition, comparisons with laser radar showed that vision sensors with a wider FOV (Field Of View) provided faster responses to cutting-in vehicles. Finally, we integrated the proposed method into a longitudinal collision avoidance system. Experimental results showed that activated braking by risk assessment using the state of the ego-vehicle and measuring the distance to upcoming obstacles could successfully prevent collisions.

• Journal of Positioning, Navigation, and Timing
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• v.8 no.4
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• pp.165-173
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• 2019

In this paper, we apply a discrete wavelet packet transform (DWPT) to reduce the influence of interference in global positioning system (GPS) signals and compare the interference mitigation performance of various wavelets. By applying DWPT to the received signal, we can gradually divide the received signal band into low-pass and high-pass bands. After calculating the average power for the separate bands, we can determine whether there is interference by comparing the value with the given threshold. For a band that includes interference, we can reconstruct the whole band signal using inverse DWPT (IDWPT) after applying a nulling method that sets all of the wavelet coefficients to 0. The reconstructed signals are correlated with the pseudorandom noise (PRN) codes to acquire GPS signals. The performance evaluation is based on the number of satellite signals whose peak ratio (defined as the ratio of the first and second correlation peak values in the acquisition stage) exceeds the threshold. In this paper, we compare and evaluate the performance of 6 wavelets including Haar, Daubechies, Symlets, Coiflets, Biorthogonal Splines, and Discrete Meyer.

• Journal of the Korea Society of Computer and Information
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• v.7 no.4
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• pp.46-51
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• 2002

In this paper, I proposed a eyebrow detection algorithm in human face, that is important element in facial recognition. The proposed algorithm consists of four processes: face region detection using color region segmentation. eye detection by template matching, eyebrow candidate region detection in detected eye region, and eyebrow detection by thresholding using the modified histogram that gets luminance value in the candidate region. The test results show that the proposed algorithm can detect eyebrow region very effectively in facial image.