• Nuclear Engineering and Technology
• /
• v.52 no.2
• /
• pp.296-307
• /
• 2020

Permanent magnet sodium flowmeter (PMSF) have been used to measure the sodium flow in fast breeder reactors. Due to the effects of irradiation, thermal cycling, time lapse, etc., the magnetic flux density of the PMSF will decrease after being used in the reactor for a period of time. Therefore, it must be calibrated regularly. But some flowmeters that immersed in sodium cannot be removed for an off-line calibration, so the on-line calibration is required. However, the best online calibration accuracy of PMSF using cross-correlation analysis method was 2.0-level without considering the repeatability. In order to further improve this work, the operational principle of the transducer in PMSF is analyzed and the design principle of the transducer is proposed. The transducers were tested on the sodium flow loop to collect the experimental data. The signal characteristics are analyzed from the time and frequency domains, respectively. The cross-correlation analysis method based on biased estimation is adopted to obtain the flow rate. The verification experimental results showed that the measurement accuracy is 1.0-level when the flow velocity is above 0.5 m/s, and the measurement accuracy is 3.0-level when the flow velocity is in the range of 0.2 m/s to 0.5 m/s.

• The Journal of the Society of Korean Medicine Diagnostics
• /
• v.13 no.2
• /
• pp.34-44
• /
• 2009

Background : Currently, as a method of standardization of prescription, questionnaire for Buzhongyiqi-Tang[補中益氣湯] was developed, and which is a Objectives : The purpose of this thesis is to testify whether differentiation of Lao Juan Shang[勞倦傷] etiology is relative to mobility of gastric smooth muscle. Methods : The subjects(20 to 65 years old; 14 males, 46 females) were isolated from drinking alcohols for 24 hours before the experiment, and fasted for 8 hours, and measured for electrogastrography(EGG) and they filled out Questionnaire for Buzhongyiqi-Tang. Results : 1. Six factors from the factor analysis of Questionnaire for Buzhongyiqi -Tang were named and classified as Spleen-Qi deficiency syndrome factor [脾虛] (factor 1), Lung-Qi deficiency syndrome factor [肺虛] (factor 2), Working factor [習慣] (factor 3), Yin-Fire factor [陰火] (factor 4), Jung-Qi deficiency syndrome factor [中氣虛] (factor 5), and Stomach-Qi deficiency syndrome factor [胃虛] (factor 6). 2. As for the reliability of Questionnaire for Buzhongyiqi-Tang, we used Cronbach's alpha coefficient. Cronbach's alpha coefficient was 0.772 for the mean of the item-total. 3. Lung-Qi deficiency syndrome factor(factor2) had significant correlation with Bradygastria Time (r=-0.312, p<0.05). 4. Working factor(factor3) had significant correlation with Bradygastria Time (r=-0.329, p<0.05). 5. Yin-Fire factor(factor4) had significant correlation with Power Ratio (r=-0.328, p<0.05). Conclusions : It is shown that Bradygastria Time and Power Ratio tended to decrease against postprandial DP increased and postprandial frequency decreased in normal case.

• Research in Community and Public Health Nursing
• /
• v.26 no.2
• /
• pp.119-127
• /
• 2015

Purpose: This study is attempted to figure out the characteristics of sexual abuse victimization in low- and high-grade elementary school children and furthermore to help develop appropriate preventive educational programs against sexual abuse by grade. Methods: Data were collected from 156 sexual abuse victims who were elementary school children and visited the Child Sexual Abuse Response Center in D City during the period from 2010 to 2012. Differences in general and victimization-related characteristics between low and high graders and the correlations among the characteristics were analyzed. Results: The results showed statistically significant difference between low and high graders in two variables: offender-victim relationship, and the type of sexual abuse. Offender-victim relationship was in a significant correlation with the duration of victimization (r=.576, p<.001), frequency of abuse (r=.546, p<.001), location (r=-.479, p<.001), and time (r=.435, p<.001). The type of sexual abuse was in a significant correlation with frequency (r=.175, p=.029) and time (r=.261, p=.001). Conclusion: Appropriate educational programs should be developed for preventing sexual assaults in consideration of difference in victimization-related characteristics between low and high graders. In addition, such programs should be applied fittingly to the learners'grade, gender, and cognitive level.

• Journal of the Institute of Convergence Signal Processing
• /
• v.8 no.1
• /
• pp.44-50
• /
• 2007

In this paper generating algorithms of the conventional chaos code sequences and a new chaos code sequence derived from the real and imaginary parts of FFT of one chaos code sequence, and the time-frequency function characteristics of generated code sequences to measure the signal resolution, are considered. And two chaos based QCSK digital communication systems-one with two different chaos code sequences, the other with FFT of one chaos code sequence-are analyzed in AWGN and fading communication channels. After analyzing the correlation functions of such sequences, the delta-like autocorrelation and near zero crosscorrelation functions of them are very suitable for chaos based spread spectrum communication systems, is verified. Through evaluating the performance of two chaos based QCSK systems above using Monte-Carlo simulation, the improvement of performance in the latter QCSK system compare favorably with that of the former system, is shown.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 2000.04a
• /
• pp.312-317
• /
• 2000

The relationship between riding comfort and the properties of flexible polyurethane foam used in car seats was quantitatively illustrated through vibration experiments with humans sitting in car seats, which were vertically shaken by vibrator. Riding comfort was estimated according to SD (Semantic Differential)-method using questionnaire, and was analyzed with a factor analysis which demonstrated the principal factors of riding comfort. At the same time, riding comfort was related to the properties of the flexible polyurethane foam with coefficients of correlation. It was also related to the behaviour of its vibration of humans sitting in the seats. As a result, it was demonstrated that the relationship between riding comfort and the flexible polyurethane foam properties varies according to the frequency of the vibration shaking the human sitting in the seat. and it was demonstrated that the frequency dependence of the relationship is strongly affected by the physical changes of the vibration modes of the human-seat vibration system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.1
• /
• pp.101-106
• /
• 2004

The phenomenon of PD(Partial Discharge) is accompanied by electromagnetic wave which can be detected by UHF(Ultra High Frequency) antenna. The signals obtaining from UHF antenna are very high rapid pulse and have wide band frequency responses. The distribution of PRPD(Phase Resolved Partial Discharge) which consisted of those pulse train can show distinct characteristics of PD sources. But it is not sufficient to discriminate among PD sources. This paper suggests that the stochastic parameters formed by preprocessing of STFT(Short Time Fourier Transform) are good tools for differentiate from PD sources. The stochastic parameters are CC(Cross Correlation) mean value, CC standard deviation, CC skewness, CC kurtosis.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.9 no.4
• /
• pp.81-89
• /
• 2006

In this paper, a watermark technique for identifying friendly and foe is proposed during communication. The speech signal is processed in several stages. First, speech signal is partitioned into small time frames and the frames are transformed into frequency domain using DFT(Discrete Frequency Transform). The DFT coefficients are quantized and the watermark signal is embedded into the quantized DFT coefficients. At the destination channel quantization errors of received signal are regarded as the watermark signal. Identification of friendly and foe are done by correlating the detected watermark and the original watermark. As in most other watermark techniques, this method has a trade off between noise robustness and quality. However, this is solved by a partial quantization and a noise level dependent quantization step. Simulation results in the various noisy environments show that the proposed method is reliable for identification between friendly and foe.

• Journal of Communications and Networks
• /
• v.14 no.4
• /
• pp.410-417
• /
• 2012

One of the premier mechanisms used in extracting unobserved signals from observed mixtures in signal processing is employing a blind source separation (BSS) algorithm. Orthogonal frequency division multiplexing (OFDM) techniques are playing a prominent role in the sphere of multicarrier communication. A set of remedial solutions taken to mitigate deteriorative effects caused within the air interface of OFDM transmission with aid of BSS schemes is presented. Four energy functions are used in deriving the filter coefficients. Energy criterion functions to be optimized and the performance is justified. These functions together with iterative fixed point rule for receive signal are used in determining the filter coefficients. Time correlation properties of the channel are taken advantage for BSS. It is tried to remove colored noise and jamming components from themixture at the receiver. Themethod is tested in a slow fading channel with a receiver containing equal gain combining to treat the channel state information values. The importance is that, these are quite low computational complexity mechanisms.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1997.04a
• /
• pp.581-587
• /
• 1997

Numerical predictions of aerodynamic noise radiated by subsonic rotors are carried out. A time domain approach for Ffowcs-Williams Hawkings equation of acoustic analogy is used in developing a comprehensive rotor/fan noise prediction program to handle both arbitrary blade shapes and loading conditions. Since only the aeroacoustic aspects of rotors are considered here, the calculations are carried out for rotors with simple aerodynamic characteristics. Broadband noise from ingestion of turbulence is also considered. By incorporating discrete frequency noise prediction of steady loading with broadband spectrum, much better correlation at the low frequency region with experimental data is obtaind. The contributions from different noise mechanisms can also be analysed through this method.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.38 no.7
• /
• pp.557-568
• /
• 1989

Using Power Spectrum Analysis, conditions of parameter convergence for a Model Reference Adaptive Control (MRAC) system are described. The general Persistent Excitation (PE) condition given in time domain can be transformed to the positiveness of auto-correlation matrix which is represented in frequency domain by the spectra of reference input signal. For an MRAC system designed with relative degree one, the existence and the uniqueness of parameter nominal values due to the variation of input spectra can be analyzed by the PE condition in frequency domain. If the input signal has 2n spectra or more, it can be shown that the nominal values exist independent of adaptive gain, input amplitudes, and magnitudes or numbers of their spectra.