• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1433-1440
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• 2015

In this paper, we propose an unambiguous correlation function to improve tracking performance for binary offset carrier (BOC) signals. Specifically, we divide a BOC sub-carrier into multiple rectangular pulses, and analyze that the BOC autocorrelation function is made up of the sum of several partial correlation functions. Then, we obtain two sub-correlation functions by combining two partial correlation functions and propose a novel unambiguous correlation function with no side-peak which can be regulated its width based on the combination of the sub-correlation functions and partial correlation functions. From numerical results, it is confirmed that the proposed correlation function provides a tracking performance improvement over the conventional correlation functions in terms of the tracking error standard deviation.

• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.1
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• pp.11-25
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• 2021

The objective of this study was to analyze the impact of activation functions on flood forecasting model based on Artificial neural networks (ANNs). The traditional activation functions, the sigmoid and tanh functions, were compared with the functions which have been recently recommended for deep neural networks; the ReLU, leaky ReLU, and ELU functions. The flood forecasting model based on ANNs was designed to predict real-time runoff for 1 to 6-h lead time using the rainfall and runoff data of the past nine hours. The statistical measures such as R2, Nash-Sutcliffe Efficiency (NSE), Root Mean Squared Error (RMSE), the error of peak time (ETp), and the error of peak discharge (EQp) were used to evaluate the model accuracy. The tanh and ELU functions were most accurate with R2=0.97 and RMSE=30.1 (㎥/s) for 1-h lead time and R2=0.56 and RMSE=124.6~124.8 (㎥/s) for 6-h lead time. We also evaluated the learning speed by using the number of epochs that minimizes errors. The sigmoid function had the slowest learning speed due to the 'vanishing gradient problem' and the limited direction of weight update. The learning speed of the ELU function was 1.2 times faster than the tanh function. As a result, the ELU function most effectively improved the accuracy and speed of the ANNs model, so it was determined to be the best activation function for ANNs-based flood forecasting.

• The Journal of Korean Physical Therapy
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• v.28 no.5
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• pp.334-340
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• 2016

Purpose: This study was conducted to investigate the effects of skater exercise on cardiopulmonary fitness and balance function in patients with mild chronic stroke. Methods: A total of ten chronic stroke patients with mild neurologic deficits were recruited. The participants were divided into two groups, a skater exercise (n=5) and a control group (n=5). Skater exercise was performed by physical therapists in the experimental group, whereas patients in the control group conducted self-exercise. One session of the intervention was carried out for 30 minutes, three times per week for eight weeks. Cardiopulmonary function, falling index, and Euro-Quality of Life-5 Dimension (EQ-5D) were measured before and after the intervention. Results: No side effects were reported during and after skater exercise intervention. The peak aerobic capacity, falling index, and EQ-5D improved significantly in the experimental group compared with the control group after eight weeks of skater exercise (p=0.002, p=0.010, and p=0.006). Significant relationships were identified between the change in EQ-5D and peak aerobic capacity (R2=0.75, p=0.002)/falling index (R2=0.65, p=0.002). Conclusion: Skater exercise was an effective physical therapy to improve cardiopulmonary fitness and balance function in patients with mild chronic stroke.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.5
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• pp.619-624
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• 2005

This work is for examining a simplified equation based on the rational formula, which can easily decide storm-water detention volume in small urban catchments. The storm-water detention volume is determined by the inflow hydrograph flowing to detention basin and the outflow hydrograph discharged from the detention basin. The ratio of average outflow over the period of rainfall duration against allowable discharge was 0.5 in former simplified equation. But this research has found that the average outflow ratio depends on the storage methodology. In the case of the on-line storage method, the average outflow ratio is a function of the time of concentration of the catchments and rainfall duration, which ranged from 0.5~1.0. In the case of the off-line storage method, the average ratio is a function of peak discharge and allowable discharge except above time of concentration and rainfall duration, where its function value ranged from 1.0~2.0. When applying this equation to small catchment in Mokpo city, South Korea, we could easily calculate the relation curve between the storm-water detention volume and allowable discharge.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.310-312
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• 2011

In complex noise environment, digital filter is being used to obtain, transport and storage original voice or image signal. Digital filter can be largely separated FIR(Finite duration impulse response) filter and IIR(Infinite duration impulse response) filter. Among FIR filter, window function has characteristic of linear phase and as can be easily set pass-band frequency, cutoff frequency and so on. In this paper, We compared with established method using transient characteristic and peak side-lobe in order to check filter characteristics after we designed the existing variants of the window function.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12C
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• pp.1214-1221
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• 2005

In this paper, we propose a digital watermarking method for still images, in which the human visual system (HVS) is used in the discrete cosine transform (DCT) domain. The modulation transfer function (MTF) of the HVS model is employed to increase the invisibility of the inserted watermark in images. The proposed watermarking method is shown to be robust to several common image processing techniques, including lowpass filtering and cropping. Also, using the energy relationship of the DCT, we derive the equation that directly computes the watermark weighting factor in the DCT domain for the specified peak signal to noise ratio (PSNR) of the still image and the length of watermark to be inserted. The difference between desired PSNR and PSNR in spatial domain is within 0.07dB for the 7 test images.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.2
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• pp.126-132
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• 2012

The technique for estimation of sound source direction is one of the important methods necessary for various engineering fields such as monitoring system, military services and so on. As a new approach for estimation of sound source direction, this paper propose the bio-mimetic localization sensor based on mechanically coupling structure motivated by hearing structure of fly, Ormia Ochracea. This creature is known for its outstanding recognition ability to the sound which has large wavelength compared to its own size. ITTF (Inter-Tympanal Transfer Function) which is the transfer function between displacements of the tympanal membranes on each side has the all inter-tympanal information dependent on sound direction. The peak and notch features of desired ITTF can be generated by using the appropriate mechanical properties. A example of estimation of sound source direction using generated ITTF with monotonically changing notch and peak patterns is shown.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5C
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• pp.437-443
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• 2012

In this paper, we propose a novel unambiguous correlation function for binary offset carrier (BOC) signal acquisition. Specifically, we first find out that the side-peaks arise due to the fact that the BOC autocorrelation is the sum of the irregularly shaped BOC sub-correlations, and then, propose an unambiguous correlation function with no side-peak by combining the sub-correlations. The proposed scheme is shown to remove the side-peaks completely for any type of BOC signal and to provide a better acquisition performance than the conventional correlation functions.

• Journal of KIEE
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• v.11 no.1
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• pp.69-77
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• 2001

This paper describes an image processing algorithm capable of recognizing road lanes by using a CDF(cumulative distribution function). The CDF is designed for the model function of road lanes. Based on the assumptions that there are no abrupt changes in the direction and location of road lanes and that the intensity of lane boundaries differs from that of the background, we formulated the CDF, which accumulates the edge magnitude for edge directions. The CDF has distinctive peak points at the vicinity of lane directions due to the directional and the positional continuities of a lane. To obtain lane-related information a scatter diagram was constructed by collecting edge pixels, of which the direction corresponds to the peak point of the CDF, then the principal axis-based line fitting was performed for the scatter diagram. Noises can cause many similar features to appear and to disappear in an image. Therefore, to reduce the noise effect a recursive estimator of the CDF was introduced, and also to prevent false alarms or miss detection a scene understanding index (DUI) was formulated by the statistical parameters of the CDF. The proposed algorithm has been implemented in real time on video data obtained from a test vehicle driven on a typical highway.

• Journal of Veterinary Clinics
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• v.36 no.3
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• pp.155-158
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• 2019

Morphologic changes or functional impairments of the papillary muscle (PM) can influence mitral valve competence. The purpose of this study was to investigate PM size and contractile function using two-dimensional and color tissue Doppler echocardiography in normal dogs. 35 unsedated Beagle dogs without cardiovascular disease were examined. The vertical (VD) and horizontal diameter (HD) of the posterior and anterior PM was measured at end-diastole, and compared with the thickness of the left ventricular posterior wall (LVPWd). Longitudinal systolic movement of the PM was quantified as myocardial velocity and strain using tissue Doppler. The VD, HD, and ratios (VD/LVPWd, HD/LVPWd, VD/HD) were significantly greater in the posterior than anterior PM (P < 0.001). The VD and HD of posterior PM and the HD of anterior PM were significantly correlated with LVPWd (r = 0.47, 0.44, and 0.42, respectively). Body weight was significantly correlated with VD of posterior PM (r = 0.37). The peak systolic tissue velocity of the PM was $4.93{\pm}1.25cm/sec$ and peak strain was $-30.83{\pm}11.92%$. PM size and systolic function can be quantitatively assessed using two-dimensional and tissue Doppler. The establishment of these objective PM measurements may be useful to evaluate morphological and functional abnormalities of the canine PM.