• Structural Engineering and Mechanics
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• v.22 no.4
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• pp.469-481
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• 2006

A new method called fuzzy factor method for the stationary stochastic response analysis of fuzzy truss with global fuzzy structural parameters is presented in this paper. Considering the fuzziness of the structural physical parameters and geometric dimensions simultaneously, the fuzzy correlation function matrix of structural displacement response in time domain is derived by using the fuzzy factor method and the optimization method, the fuzzy mean square values of the structural displacement and stress response in the frequency domain are then developed with the fuzzy factor method. The influences of the fuzziness of structural parameters on the fuzziness of mean square values of the displacement and stress response are inspected via an example and some important conclusions are obtained. Finally, the example is simulated by Monte-Carlo method and the results of the two methods are close, which verified the feasibility of the method given in this paper.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.11 no.1
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• pp.13-20
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• 2004

Purpose: This study was conducted to evaluate the effect of open laboratory self-directed practice in improving nursing skill competency. Method: This study was a one group posttest only design that examined the competency in basic nursing skills after traditional education and open laboratory self-directed practice. Students participated in traditional education and open laboratory practice through self-study. Whenever practice was done, the item of practice and time were measured and documented. Collected data were analyzed by frequency, percentages, averages and standard deviations, and Pearson correlation coefficients. Result: 1 The average number of students who participated in the open lab self-directed practice was 53.9 (64.2%) and the total number of hours of participation was 1567.5 minutes per year. Each student participated for an average of 29.1 minutes per year. 2. Analysis showed a statistically positive correlation between practical skill and open laboratory self-study (r=0.252, p=0.048).

• Journal of Korea Multimedia Society
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• v.21 no.12
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• pp.1370-1378
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• 2018

There is a problem to measure neutral bio-signals during sleep because of inconvenience of attaching lots of sensors. In this study, we measured single electrocardiogram(ECG) signal and analyzed the correlation with sleep. After R-peak detection from ECG signal, we extracted 9 features from time and frequency domain of heart rate variability(HRV). Mean of HRV, RR intervals differing more than 50ms(NN50), and divided by the total number of all RR intervals(pNN50) have significant differences in each sleep stage. Specially, the mean HRV has an average of 87.8% accuracy in classifying sleep and awake status. In the future, the measurement ECG signal minimizes inconvenience of attaching sensors during sleep. Also, it can be substituted for the standard sleep measurement method.

• Journal of Families and Better Life
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• v.9 no.1 s.17
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• pp.95-112
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• 1991

This study is planned to provide the basic idea to seek for the appropriate Time Management Strategies and to investigate the Time Management Strategies and household work time of wives. For these research tasks, the data are collected through the questionnaire rand 479 respondents were housewives in seoul. Their data are analyzed using Frequency, ANOVA, Pearson's Correlation Analysis, Simple Regression Analysis, Multiple Regression Analysis. The Major findings of this study were as follows ; 1) There are significant differences in the time management strategies according to housewife's age, education level, and employment status, children's number, the type of housing, the type family, income and sex role attitude. 2) There are significant differences in the household work time according to housewife's age, education level, employment status, family size, children's number, type of housing, income, sex role attitude and time pressure perceptibility. 3) The Household work time is found to be negatively correlated to the Time Management Stategies except the adjustment of leisure and sleep time. 4) The Household work time is significantly related to housewife's employment status and the adjustment of leisure and sleep time.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.74.2-74.2
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• 2016

It is important to know how well observation errors are removed in the calibration process prior to ensuing scientific research. In mm-VLBI observations, a radio wave suffers from an atmospheric propagation delay due to the rapid change of atmospheric refraction. It makes phases of VLBI correlation output fluctuate rapidly, which essentially decreases the coherence of phases and reduces the integration time. Consequently, it is challenging to achieve a high signal-to-noise ratio and enhance the quality of scientific output. Among the causes of the atmospheric propagation delay, water vapor in the troposphere is the most decisive factor to affect phase errors in the high frequency range (> 10GHz). It is expected to have the non-dispersive characteristic that enables to introduce new calibration strategy, Frequency Phase Transfer (FPT). This new method utilizes low frequency phases to compensate phase errors in high frequency bands. In addition, Korean VLBI Network (KVN) which benefits from the simultaneous 4-channels (22/43/86/129 GHz) observations is ideal to probe FPT performance. In order to evaluate FPT performance of KVN, we present the results of FPT phase analysis and discuss its performance.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.1
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• pp.91-107
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• 2003

A 2-dimensional search process in the time and frequency domain is required to acquire the GPS signal, when the code phase and the carrier Doppler for the specified GPS satellite signal are unknown. This paper proposes a new scheme, called Squared-D Searching Method, which can reduce the number of carrier frequency candidates, and a new scheme, named extended Multiple Correlator(XMC), which can reduce the number of code phase candidates. The Squared-D Searching Method can take the twice of Doppler frequency, therefore it can find carrier frequency candidates. The XMC is different from the general multiple correlator in that a combined form of the locally generated codes is used for despreading. Also, this paper tries to analyze a signal detection probability of a GPS receiver under more realistic environments. The result shows that lower detection probability can be obtained when the phase differences among the codes are larger in the correlation arms of a multiple correlator. This phenomenon is not easy to explain with the previous results. And besides, the result shows that proposed acquisition schemes give better performance than a conventional acquisition scheme.

• Korean Journal of Environment and Ecology
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• v.31 no.2
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• pp.127-134
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• 2017

This study was conducted to identify the reproductive behavior of the barn swallow. The study was carried out in Gwangju, Korea during the 2013 breeding season. In the morning, the nest-building frequency was 14.2~31.0 trips/h (10.2~19.8 trips/h by male and 4.0~11.4 trips/h by female). The nest-building activity took 7.6~15.9 min/h (4.8~8.1 min/h by male and 2.8~8.0 min/h by female). The nest-building time by female ($40.0{\pm}27.9sec/trip$) was about 1.5 times longer than the nest-building time by male ($26.1{\pm}15.5sec/trip$). Only the female incubated the eggs. The Incubation time was $50.6{\pm}17.5min/h$ (84%) at 6h, 24.5 min/h (40.8%) at 7h and 15.6 min/h (26.0%) thereafter. During daytime, the female incubation time showed a highly significant difference (p<0.001), and the incubation time at 6h was higher than that at other times. There was a significantly negative correlation between female incubation time and the mean air temperature(p<0.05). The frequency of feeding was $385.2{\pm}66.9trips/nest$ in the daytime ($219.2{\pm}37.1trips/nest$ by male and $166.0{\pm}30.8trips/nest$ by female). The frequency of feeding per hour was $32.1{\pm}12.3trips/h$ ($18.3{\pm}7.8trips/h$ by male and $14.3{\pm}4.5trips/h$ by female). The frequency of feeding per hour showed a significant difference in the range of 10h(p<0.05) and 15h(p<0.01) by sex. The time of feeding by female ($40.9{\pm}83.3sec/trip$) was longer than the time of feeding by male ($12.3{\pm}31.0sec/trip$). The juvenile defecation frequency was $45.6{\pm}8.4times/nest$ per day and showed a positive correlation with feeding frequency (p<0.05). The results of this study will be helpful in understanding the reproductive behaviors of the swallow adapted to the environment in Korea.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.10
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• pp.139-147
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• 2015

Steady state visual evoked potential (SSVEP) has been actively studied because of its short training time, relatively higher signal-to-noise ratio, and higher information transfer rate. There are two popular analysis methods for SSVEP signals: power spectral density analysis (PSDA) and canonical correlation analysis (CCA). However, the PSDA is known to be vulnerable to noise due to the use of a single channel. Although conventional CCA is more accurate than PSDA, it may not be appropriate for the real-time SSVEP-based BCI system when it has short time window length because it uses sinusoidal signals as references. Therefore, the two methods are not efficient for the real-time BCI system that requires a short TW and a high recognition accuracy. To overcome this limitation of the conventional methods, this paper proposes a frequency recognition method with a combination of CCA and PSDA using the difference between powers of canonical variables obtained from the results of CCA. Experimental results show that the performance of the combination of CCA and PSDA is better than that of CCA for the case of a short TW.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.6 no.1
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• pp.51-63
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• 1999

This study examined two differences in physical and psychological recovery patterns after surgery in the elderly. The sample consisted of 40 patients with abdominal surgery In five large hospitals in Seoul. The data for this study were collected from Apr. 20 to Nov. 26 by structured questionnaire, chart review and call. Physical recovery was assessed by ADL, a Cantril Ladder Scale and a Visual Analogue Scale. Psychological recovery was measured by the Geriatric depression Scale and a Cantril Ladder Scale. The data were analyzed using frequency, percentage, Pearson Correlation Coefficient, and MANOVA by SPSS/WIN. The result are as follows : 1. Physical recovery indicated significant improvement over time with the exception of ADL(F=.812 p=.449). Perceived physical health were significantly improved(F=6.189 p=.004). Pain & discomfort was significantly decreased(F=3.927 p=.025). 2. Perceived psychological health was significantly improved over time(F=20.648 p=.000), but depression showed no statistical significance improvement over time(F=1.393 p=.256). 3. There were no significant effects of sex, age, complication and combined chronic diseases on physical and psychological recovery patterns. 4. There were significant correlations between operation time and pain(r=-.331 p=.020), recovery time and perceived psychological health(r=-.320 p=.024), recovery time and pain(r=.404 p=.005). There were significant correlations between admision period and ADL(r=-.418 p=.004), perceived physical health(r=-.354 p=.014), depression(r=.280 p=.042), and perceived psychological health(r=-.447 p=.002). BRAS showed significant correlation with ADL(r=-.458 p=.002). 5. With an increase in the degree of perceived health(physical and psychological), ADL was significantly increased. With an increased in the degree of depression and pain, ADL and perceived health(physical and psychological) were significantly decreased. In conclusion, the elderly patient recovered significantly over time with the exception of ADL and depression. It these we suggested to considered when planning care for elderly patients.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.4
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• pp.310-317
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• 2013

In this paper an ESPRIT-based super-resolution time delay estimation algorithm is developed for real-time locating system (RTLS) and its performance is analyzed in various multipath environments. The performance of the existing correlation method for time delay estimation seriously degrades in multipath environments where the relative time delays of multipath signals are less than a PN chip. To solve the problem we shall develop a frequency domain super-resolution time delay estimation algorithm using the ESPRIT, the most representative super-resolution direction-of-arrival (DOA) estimation algorithm, and analyze its performance in various multipath environments.