• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.1234-1238
• /
• 2005

As the low power GPS signal is susceptible to interference, interference can seriously degrade the performance of GPS receiver. This paper designs a ANIEF(Adaptive Narrowband Interference Excision in Frequency domain) filter that removes narrow band interferences with low signal loss. This filter uses the pre-correlation technique and attempts to filter out the interference in the frequency domain. The interference excision performance of the designed filter is evaluated for various interferences using the ANIEF filter inserted GPS software receiver and the interference generator. Interferences considered in this paper are single-tone CWI(Continuous Wave Interference), multi-tones CWI, pulsed CWI, and swept CWI. The narrowband interference excision filter in frequency domain is very effective against various interferences and the strong interference with a simple structure. However, the signal power loss is unavoidable while transforming. In this paper, the hamming window and overlap technique are adopted to reduce the signal power loss. Finally, the interference excision performance and the reduced signal power loss of the ANIEF filter are shown.

• Journal of Communications and Networks
• /
• v.15 no.5
• /
• pp.496-503
• /
• 2013

In an orthogonal frequency division multiplexing system, conventional interpolation techniques cannot correctly balance performance and overhead when estimating dynamic long-delay channels in single frequency networks (SFNs). In this study, classical filter analysis and design methods are employed to derive a complex interpolator for maximizing the resistible echo delay in a channel estimator on the basis of the correlation between frequency domain interpolating and time domain windowing. The coefficient computation of the complex interpolator requires a key parameter, i.e., channel length, which is obtained in the frequency domain with a tentative estimation scheme having low implementation complexity. The proposed complex adaptive interpolator is verified in a simulated digital video broadcasting for terrestrial/handheld receiver. The simulation results indicate that the designed channel estimator can not only handle SFN echoes with more than $200{\mu}s$ delay but also achieve a bit-error rate performance close to the optimum minimum mean square error method, which significantly outperforms conventional channel estimation methods, while preserving a low implementation cost in a short-delay channel.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.35 no.2
• /
• pp.30-36
• /
• 2012

This study is aimed to show that an asymmetric load in the frontal plane leads to an increase in low back loading and fatigue in comparison with a symmetric load when workers lift an external weight by investigating previous studies and verifying the phenomenon with an experiment. Ten male subjects are required to lift and hold an given external load at 70cm height during 50sec, then the EMG amplitude and median frequency on bilateral low back muscle groups (Longissimus, Iliocostalis, and Multifidus) are recorded and analyzed. Independent variables are two-level load weight (13kg, 20kg) and three-level LCG (Center, 6.5cm to the right, and 13cm to the right), and dependent variables are EMG amplitude average, difference, and Fatigue Index (FI). Results show that load weight increases significantly amplitude average and FI, but LCG does significantly amplitude difference and FI significantly (P-value < 0.05). Also the correlation coefficient between amplitude difference and FI is over 0.99. These implies that trunk loading should be explained by not EMG amplitude but muscle fatigue aspect since the association between an external load and amplitude is linear, but the relationship between an external load and median frequency as muscle fatigue index is almost exponential.

• Journal of Electrical Engineering and Technology
• /
• v.11 no.2
• /
• pp.519-528
• /
• 2016

In order to achieve fast computational speed with good visual quality of output video, we propose a frequency domain based new fractal video compression scheme. Normalized cross correlation is used to find the structural self similar domain block for the input range block. To increase the searching speed, cross correlation is implemented in the frequency domain using FFT with one computational operation for all the domain blocks instead of individual block wise calculations. The encoding time is further minimized by applying rotation and reflection DFT properties to the IFFT of zero padded range blocks. The energy of overlap small size domain blocks is pre-computed for the entire reference frame and retaining the energies of the overlapped search window portion of previous adjacent block. Quadtree decompositions are obtained by using domain block motion compensated prediction error as a threshold to control the further partitions of the block. It provides a better level of adaption to the scene contents than fixed block size approach. The result shows that, on average, the proposed method can raise the encoding speed by 48.8 % and 90 % higher than NHEXS and CPM/NCIM algorithms respectively. The compression ratio and PSNR of the proposed method is increased by 15.41 and 0.89 dB higher than that of NHEXS on average. For low bit rate videos, the proposed algorithm achieve the high compression ratio above 120 with more than 31 dB PSNR.

• PNF and Movement
• /
• v.8 no.1
• /
• pp.67-77
• /
• 2010

Purpose : The purpose of this study was to investigate the usefulness of clinical balance tests through the correlation of balance evaluation using by forceplate in elderly. Methods : Thirty nine healthy elderly subjects (14 males, 25 females) participated in the study. The subjects were evaluated with clinical balance tests [(Berg balance scale (BBS), Functional reach test (FRT), Tinetti's performance oriented mobility assessment (POMA), and one leg standing (OLS)]. Static balance evaluation was assessed by using forceplate. Center of pressure (COP) parameters were obtained using it as total path distance, total sway area, X mean frequency and Y mean frequency for 20 seconds in the following conditions: (1) comfortable standing with eyes opened and closed, (2) uncomfortable standing with eyes opened and closed. After static balance evaluation tested, dynamic balance evaluation was assessed. COP parameters were error distance and area during sine curve trace. COP parameters were movement time, error distance, and maintained time in the circle during COP movement task. Results : Clinical balance tests showed statistically significant correlation between static and dynamic balance evaluations. Among the clinical balance tests, the BBS, POMA, and OLS showed significant correlation with to assess the balance ability of elderly in clinical setting both evaluations. Conclusion : Clinical balance tests can be recommended in clinical setting because of low costs and simplicity.

• Journal of Environmental Science International
• /
• v.25 no.10
• /
• pp.1407-1415
• /
• 2016

In this study, we investigated the relationship between noise reduction and the community structure of nine groups of typical plant communities as well as the reduction in noise at different frequencies. The semantic differential method was adopted to explore the perception of noise reduction. The results indicated that there was a significantly positive correlation between noise reduction and coverage, a significantly negative correlation between noise reduction and bifurcate height, and a negative correlation between noise reduction and bare rate. However, there was no significant correlation between noise reduction and height, diameter at breast height, or crown width. The reduction of middle-frequency noise was better than that of low- and high-frequency noise. The indicators "quiet" and "calm" showed that plant communities could reduce the noise perceived by humans. However, overly dense woodland caused nervousness, fear, depression, and other negative effects. Relatively open environments and those with large forest gaps obtained the highest evaluation.

• Journal of Korean Medicine for Obesity Research
• /
• v.12 no.2
• /
• pp.8-16
• /
• 2012

Objectives: This study is designed to report the correlation between Body Mass Index(BMI), Heart Rate Variability(HRV), stess, drinking alcohol, coffee and smoking. Methods: From 1st January 2010 to 31st December 2012, We tested on 458 patients who hospitalized in Cheong Yeon Korean Medicine Hospital for reducing their weights, then we collected the statistical analysis with the result of their HRV and the special survey. Results: This experiment was studied on total 458 patients, 27 were men and 431 were women. The average of the age of men was $28.23{\pm}4.22$ and $24.31{\pm}385$ was women. There were significant differences in BMI, Low frequency(LF), High frequency(HF), stress score, frequency of drinking alcohol, smoking and drinking coffee followed by their ages. When we looked at the correlation between obesity with smoking and drinking coffee, we can see that the BMI increased, the frequency of drinking alcohol was decreased, however there were no statistic correlation in smoking and drinking coffee with BMI. Conclusions: With the result of HRV, we can suggest the BMI and stress score are correlated each other but we need further studies about passive stress relief by taking favourite food such as drinking alcohol, smoking, drinking coffee, etc.

• Journal of Korean Medicine for Obesity Research
• /
• v.9 no.2
• /
• pp.33-45
• /
• 2009

Objectives This study was performed to evaluate the relation between hair tissue mineral elements(HTME) and Heart rate variability(HRV) of the metabolic syndrome(MS). Methods 89 persons(41-69 ages) who visited Oriental hospital for medical examination were divided MS group(n=22) and control group(n=67). HTME and HRV were compared, and were analyzed correlation with five contents of the MS. Results (1) In total subjects, waist circumference had a positive correlation with Pb. Blood pressure had a negative correlation with Mg. High density lipoprotein cholesterol(HDL-chol) had a negative correlation with Pb, Sb and K, while positive correlation with Ca/K. Triglyceride(TG) had a negative correlation with Mg and Na/K, while positive correlation with K and Ca/Mg. (2) In total subjects, TG and fasting blood sugar(FBS) had negative correlation with high frequency(HF), while positive correlation with low frequency/high frequency ratio(LF/HF). (3) In MS group, most of the level of toxic minerals were higher, and the level of major nutritional minerals were lower, but there were no statistical signficance. In two groups, there is no contrast between the correlations of the MS contents and HTME. (4) In MS group, HF was significantly lower and LF/HF was higher than normal group. LF/HF had a negative correlation with waist circumference in MS group, while positive correlation in normal group. (5) In total subjects, TP had a positive correlation with Mg. In two groups, there is no contrast between the correlations of the MS contents and HRV. However LF/HF had a positive correlation with Na in MS group, TP and LF had negative correlation with Ca, while RMSSD and HF had negative correlation with Cu in normal group. Conclusion These results may suggest that HTME and HRV are useful in diagnosing and preventing the metabolic syndrome.

• Journal of Families and Better Life
• /
• v.25 no.2 s.86
• /
• pp.47-58
• /
• 2007

The purpose of this study is to examine children's/adolescents' motives for playing internet games and adaptation to school in accordance with their frequency levels of playing internet games. Participants were 236 children from grades 4, 5, and 6 in two elementary schools and 237 adolescents from grades 1, 2, and 3 in one middle school. They were measured on frequency levels of playing internet games, motives for playing internet games, and adaptation to school. Collected data were analyzed by SPSS WIN 12.0 for reliability, frequency, Chi-square test, t-test, Pearson's correlation, and one way ANOVA. Major findings of the research are as follows: First, children's/adolescents' frequency levels of playing internet games differed by their gender. The male ratio was much higher than the female ratio in the potential risk group and the high risk poop. In contrast, no grade differences on the frequency levels of playing internet games were found. Second, children's/adolescents' motives for playing internet games differed by their gender. Especially, among the motives the greatest difference between male and female was marked for 'Social Relationship'. Third, children's/adolescents' motives for playing internet games differed by their frequency levels of playing internet games. For 'Conformity,' the low risk group differed from the high risk group. For 'Spending Time', 'Benefit', 'Competition', and 'Social Relationship', the low risk group differed from the potential risk group and also from the high risk poop. Fourth, children's/adolescents' adaptation to school differed by their frequency levels of playing internet games. The high risk group exhibited a low level of adaptation in 'Academic Activities', 'a subcategory of adaptation to school.

• Korean Journal of Human Ecology
• /
• v.16 no.3
• /
• pp.479-490
• /
• 2007

This study examines undergraduate students' intimacy toward the grandmother and their attitudes toward the elderly and aging. The study also identifies the variances that influence undergraduate students' intimacy toward the grandmother. The subjects were 397 undergraduates. Statistical analysis was conducted to examine frequency, percentage, mean, standard deviation, Cronbach's ${\alpha}$, t-test, Duncan test, ANOVA, and stepwise multiple regression. The results of this study were as follows; 1) The undergraduates' attitudes were mid-range, but their intimacy level toward their grandmother was high. 2) The undergraduates' intimacy level toward the grandmother differed significantly according to gender, experience of cohabitation, the presence of her, and religion, and it showed a significant correlation with attitudes toward the elderly and aging traits, period of cohabitation, and frequent contact with the grandmother. The undergraduates' intimacy level toward grandmother-in-low, however, was significantly different according to the religion. There was also had a significant correlation with the undergraduate students' attitudes toward the elderly and aging traits. 3) The variables that affect the undergraduates' intimacy level toward the grandmother were attitude, frequency of contact with the grandmother, gender, period of cohabitation, experience of cohabitation, and the presence of the grandmother, which explained about 35% of total variance. Attitudes toward the elderly and aging traits were very important variables for undergraduates' intimacy with their grandmother. The undergraduates' intimacy toward grandmother-in-low was affected by the variables of attitude, religion, experience of volunteer, frequency of contact with the grandmother, gender, and the presence of grandmother, which explained about 24% of the total variance. Attitude toward the elderly and aging traits were the most important variables for undergraduates' intimacy with their grandmother-in-low.