• Research in Community and Public Health Nursing
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• v.8 no.2
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• pp.347-367
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• 1997

The purpose of this study was to investigate drug abuse and to find related factors among high school students. The subjects for this study were 973 students from 10 high schools in Taegu city. The data were collected from September 30, 1996 to October 30, 1996. The questionnaire developed by Kim Soyoaja (1991) surveyed adolescent drug use and questions on smoking and drinking were readjusted and added by the researcher based on review. The data was analyzed using frequency, percentage, $X^2-test$, t -test, Pearson Correlation Coefficient with the SPSS /PC+. The results of this study were summarized as follows: 1. The proportion of students who drank alcohol 1-2 times or more per year was 52.4% and smoked Cigarette 1 -2 times or more per year was 20.8%. The 7 different drugs(Analgetics 5.7%. sleeping pills and sedatives 4.2%, antihistamines 1.1%. stimulants 7.7%, hallucinogens 0.8%, inhalants 3.3%, and narcotics 0.6%) were also evaluated. 2. There was a significant relationship between drinking and type of school($X^2$=62.97, p<.0l), grades($X^2$=33.86, P<.001), school life($X^2$= 19.04, p<.001), and delinquent friends($X^2$= 64.72, P<.001). 3. There was a significant relationship between smoking and type of school($X^2$=153.65, p<.001), grades ($X^2$=67.53, p<.001), their respect for teachers ($X^2$=33.80, p<.001) school life($X^2$ =50.87, p<.001), and delinquent friends($X^2$ =85.28, p<.001). 4. There was a significant relationship between the 7 different kinds of drug abuse and type of school ($X^2$=14.65, p<.01), grades($X^2$=12.89, p<.01), their respect for teachers ($X^2$=8.46, p<.05), and delinquent friends($X^2$=22.42, p<.001). 5. There was a significant relationship between a parent's habitual drug abuse and the 7 different kinds of drug abuse($X^2$=7.78, p<.01), as well as a parent's attitude toward drugs and the 7 different kinds of drug abuse($X^2$=6.33, p<.05). 6. There was a significant difference between drinking(t=-12.53, p<.001), smoking(t=-15.98, p<.001), the 7 different kinds of drug abuse(t=-5.77, p<.001), and the respondant's delinquent experience. 7. There was a correlation between drinking and smoking(r=.4166, p<.001), drinking and the 7 different kinds of drug abuse(r=.2200, p<.001), smoking and the 7 different kinds of drug abuse(r=.1428, p<.05). There was a correlation between drinking and smoking(r=.5977, p<.001), drinking and the 7 different kinds of drug abuse(r=.2849, p<. 001), smoking and the 7 different kinds of drug abuse(r=.1711, p<.05) among male students. There was a correlation between drinking and smoking(r=.4219, p<.001), drinking and the 7 different kinds of drug abuse(r=.2611, p<.001), smoking and the 7 different kinds of drug abuse(r=.1764, p<.001) among female students. 8. There was a correlation between drinking and family stability(r=.0709, p<.05) drinkry and parent -child relationships (r=.1321, p<.01), drinking and mother's rearing attitude(r=.0704, P<.05), smoking and parent -child relationships(r=.0813, P<.05). There was a correlation between drinking and family stability(r=.14S7, p<.01), drinkng and parent-child relationships(r=.2147, p<.001), smoking and family stability(r=.1544, p<.01), smoking and parent. -child relationships (r=. 2018, P<.01) among male students. There was a correlation between drinking and family stability(r=.1l21, p<.05), drinking and mother's rearing attitude (r=.0988, P<.05), smoking and parent -child relationships (r=. 0940, P<.05) among female students. 9. There was a significant difference between the 7 different kinds of drug abuse and family stability (t=2.23, p<.05), parent-child relationships (t=4. 34, p<.001), satisfaction with family (t=4.02, p<.001), father's rearing attitude(t=3.04, p<.01), mother's rearing attitude(t=2.87, p<.01). The distribution channel of drugs including alcohol beverages and cigarettes should be evaluated and restructured to discourage student's temptation and to limit accessibility. The step by step preventive teaching on alcohol drinking and cigarette smoking is needed from middle school to help prevent further drug abuse.

• Journal of the HCI Society of Korea
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• v.9 no.1
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• pp.11-21
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• 2014

We present an experimental framework to analyze the physical reactions and causal factors of Visually Induced Motion Sickness (VIMS) using electroencephalography (EEG) signals and vital signs. We studied eleven subjects who are voluntarily participated in the experiments and conducted online and offline surveys. In order to simulate videos including global motions that could cause the motion sickness, we extracted global motions by optical flow estimation method from hand-held captured video recordings containing intense motions. Then, we applied the extracted global motions to our test videos with action movies and texts. Each genre of video includes three levels of different motions depending on its intensity. EEG signal and vital sign that were measured by a portable electrocorticography device and an electronic monometer in real time while the subjects watch the videos including ones with the extracted motions. We perform an analysis of the EEG signals using Distance Map(DM) calculated by correlation among each channel of brain signal. Analysis using the vital signs and the survey results is also performed to obtain relationship between the VIMS and causal factors. As a result, we clustered subjects into three groups based on the analysis of the physical reaction using the DM and the correlation between vital sign and survey results, which shows high relationships between the VIMS and the intensity of motions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.285-293
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• 2017

The purpose of this study is to examine the relationship between the Minnesota Multiphasic Personality Inventory(MMPI-2) clinical scales and the self-regulation quotient of the brain quotient. The test in this study was performed by 41 adults over 20 years old and was done using the MMPI-2, which is a self-reporting method. EEG was performed using a 2-channel EEG System at Fp1 and Fp2. The analysis showed a negative correlation between scale 2(D), which is the MMPI-2 clinical scale, and the SRQ(Self Regulation Quotient) relaxation status, which is the related alpha rhythm. Scale3(Hy) showed a positive correlation with the SRQ concentration status and low ${\beta}$ rhythm. Scale7 in the MMPI-2 clinical scales showed a negative correlation with the SRQ relaxation status, which is the alpha rhythm. This means that MMPI-2 and SRQ can be used complementarily in the field of counseling. These results could be interpreted in three ways. First, people with depression are sensitive to other people's attention and evaluation. Therefore, they tend to expend a lot of energy when forming interpersonal relationships, and if they do not learn to relax, their fatigue can easily be increased. Second, people who seek other people's interest and have a cheerful spirit are considered to be highly active. Third, highly stressed people with anxiety and tension seem to easily become tired and their irritation and discomfort may be increased in consequence.

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.4
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• pp.819-830
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• 2017

An FM radio based PCL system is a passive radar technique for detecting the multiple moving targets from FM radio signals and tracking the trajectories of the targets by calculating the cross-correlation function of direct-path signal and target echo signals. However, the interference signals are received from a surveillance channel, which is designed to receive the target echo signals. Because of this problem, the target echo signals are masked by the strong interference signals and this makes it difficult to detect the true targets from the cross-correlation function. Adaptive filters are known as effective methods for suppressing the interference signals but there is a problem to present their accurate performances in the PCL system because many literatures used the cross-correlation function and the ratio of input and output power as a measure of the performance analysis. In this paper, a performance analysis method is proposed to evaluate the performance of interference cancellation algorithms. By using the property that each component of the filter weight vector is adjusted to suppress the specific interference signal, a performance measure of the interference signal suppression is defined by a function of adaptive filter weights. Based on the proposed method, we compare the performance of the adaptive filters used in the PCL system. Simulation results show that the proposed method can be very effective for evaluating the performance of interference cancellation algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.11
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• pp.985-993
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• 2014

This paper suggested a new evaluation method for optimal HUD position through a correlation based on between biological signal as and statistical analysis which using (Electroencephalogram, EEG) and ANOVA. This experiment was conducted two kinds of method to evaluate the optimal HUD position. At first, visual stimulus suggested from six different positions(the top and the bottom of the left, the top and the bottom of the center and the top and the bottom of the right on the screen) in laboratory and an object image was shown for 30 seconds in a screen which has $235{\times}197cm2$ size. And second, HUD image was configured from three different positions and an object image was shown for 30 seconds in a screen. EEG, which used ${\alpha}$-wave and ${\beta}$-wave for evaluate an emotional stability, were measured from Fp1, Fp2, F7 and F8 channel based on ten to twenty electrode system. From the result in laboratory, F7 ${\beta}$-wave was shown statistically significant to significance probability of 0.006 and between ${\alpha}$-wave and ${\beta}$-wave were showed a negative correlation(r=-0.190). Also, Both the top of left and the bottom of center were showed lower ${\beta}$-wave than the bottom of right. From the result in railway simulator, Fp1 ${\beta}$-wave was appeared statistically significant as significance probability of 0.033 and it was showed lower ${\beta}$-wave than center. The outcome of this study will be helpful about evaluation of optimal HUD position through correlation between alpha wave and beta wave.

• Journal of Broadcast Engineering
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• v.25 no.6
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• pp.870-881
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• 2020

This paper presents cell ID (cell identity) detection schemes using PSS/SSS (primary synchronization signal/secondary synchronization signal) for 5G NR (new radio) system and evaluates the detection performance. In this paper, we consider two cell ID detection schemes, i.e. two-stage detection and joint detection schemes. The two-stage detection scheme consists of two stages which estimate a channel gain between a transmitter and receiver and detect the PSS and SSS sequences. The joint detection scheme jointly detects the PSS and SSS sequences. In addition, this paper presents coherent and non-coherent combining schemes. The coherent scheme calculates the correlation value for the total length of the given PSS and SSS sequences, and the non-coherent combining scheme calculates the correlation within each group by dividing the total length of the sequence into several groups and then combines them non-coherently. For the detection schemes considered in this paper, the detection error rates of PSS, SSS and overall cell ID are evaluated and compared through computer simulations. The simulation results show that the joint detection scheme outperforms the two-stage detection scheme for both coherent and non-coherent combining schemes, but the two-stage detection scheme can greatly reduce the computational complexity compared to the joint detection scheme. In addition, the non-coherent combining detection scheme shows better performance under the additive white Gaussian noise (AWGN), fixed, and mobile environments.

• Journal of the Korean earth science society
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• v.21 no.6
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• pp.703-718
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• 2000

In order to investigate interannual variation of total ozone and reflectivity over the globe, Nimbus-7/TOMS data were used on the monthly mean and its anomaly for the period of 1979-92. This study also examined MSU channel 4(Ch4; lower-stratosphere) brightness temperature data and two model reanalyses of NCEP and GEOS to compare the ozone variation with atmospheric thermal condition. In addition, the MSU channel 1(Ch1 ; lower-troposphere) brightness temperature was used to compare with the reflectivity. The ozone showed strong annual cycle with downward trend(-6.3${\pm}$0.6 DU/decade) over the globe, and more distinct response to volcanic eruption than El Ni${\tilde{n}$o. The relationship between total ozone and MSU Ch4 observation, and between the ozone and model reanalyses of lower stratosphere temperature showed positive correlation(0.2-0.7) during the period of 1980-92. Reflectivity increased interannually by 0.2${\pm}$0.06%/decade over the globe during the above period and reflected El Ni${\tilde{n}$o(1982-83, 1991-92) well. Its variability in annual cycle was remarkably smaller in tropics than in higher latitudes. This is inferred due to cloud suppression and tropical upwelling regions. Reflectivity correlated negatively(-0.9) to the Ch1 temperature over the globe, but positively(0.2) over tropical ocean. The positive value over the ocean results from the effect of microwave emissivity which increases the Ch1 temperature with enhanced hydrometeor activity. Significant correlations between total ozone and the Ch4 temperature, and between reflectivity and the Ch1 Suggest that the TOMS data may use valuably to better understand the feedback mechanism of climate change.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.107-116
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• 2014

A volume density of roughness correction blocks in a channel is defined and the corresponding roughness coefficient(n) is estimated by analyzing the diverse hydraulic characteristics of VR, the product of the average velocity and the hydraulic radius, block Reynolds number ($Re^*$), drag coefficient ($\acute{C}_D$), and the roughness coefficient ($n_b$) of bottom shear. The increase of VR and block Reynolds number causes the exponential decrease of roughness coefficient converged to a constant value as expected. The drag coefficient also exponentially decreases as block Reynolds number increases as well. The drag force is governed by the block shape defined by volume density in high block Reynolds number of turbulent flow region. For more accurate estimation of roughness coefficient the use of the correlation equation of it is required by block Reynolds number and volume density. The regression equations for n-VR, $\acute{C}_D-Re^*$, and $n_b-\acute{C}_D$ are presented. The regression equations of roughness coefficient are also presented by block Reynolds number and volume density. The developed equation of roughness coefficient by block Reynolds number and volume density has practical use by confirming the coincidence between the experimental results and the results of HEC-RAS using the developed equation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1335-1342
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• 2014

Shallow water depths were estimated using Compact Airborne Spectrographic Imager (CASI)-1500 and mapped to analyze the bottom bathymetry changes due to the rip currents in Haeundae beach, South Korea for the first time. The depths were estimated empirically using the maximum reflectances from 420nm to 597nm wavelength of CASI and 47 in situ water depth measurements, which were compared with ground-truth bathymetry measurements. The comparisons showed that the RMSE was 1.1m with a correlation coefficient of 0.76. In addition, CASI imagery showed remarkably detailed bottom features, especially those resulting from the rip currents within the beach. Two different channels carved by the rip current were analyzed and characterized with respect to the width and slope compared to surrounding regions. While the west side of the channel showed a wide and gentle slope, the east side of the channel showed a narrow and steep slope. The estimated bathymetry map revealed that the uneven offshore bottom features were related to the transport and accumulation of sediments by the rip current, which reaches hundreds of meters offshore. Accordingly, the accumulated sediments were estimated by adding topography changes compared to the depths of the non-rip current regions. The sediments were accumulated in off channels as much as almost twice the amount of annual sand supplements along the Haeundae beach.