• Design & Manufacturing
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• v.15 no.2
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• pp.56-62
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• 2021

In this study, design technology of a non-mechanical flow meter using fluidic oscillation generated during the fluid flow in the chamber was investigated. To with respect to design a splitter, which is the most important factor in fluid oscillation, a transient flow simulation analysis was performed for three types of shapes and changes in inlet flow velocity. The oscillation characteristics with respect to the time in each case were compared, and it was confirmed that the SM03 model was the best among the presented models. In addition, the FFT analysis of the fluid oscillation results for the SM03 model was used to obtain a linear correlation between the flow velocity change and the maximum frequency, and a frequency of 20.957 (Hz/m/s) per unit flow velocity was obtained. Finally, injection molding simulation and molding experiment of the chamber with the designed splitter were performed.

• Journal of the Institute of Convergence Signal Processing
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• v.4 no.4
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• pp.23-29
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• 2003

In this paper, we propose an idea for the improved 3-D sound system using conventional stereo headphones to obtain a better sound diffusion from the mono-sound recorded at an anechoic chamber. We use the HRTF(Head Related Transfer Function) for the sound localization and the wavelet filter bank with time delay for the sound diffusion. And we test the modified HRTF with the various sampling rate. We investigate the effects of the 3-D sound depending on the length of time delay at lowest frequency band. Also the correlation coefficient of the signals between the left channel and the right channel is measured to identify the sound diffusion. At last we obtain the diffusion sound using Cool Edit for reverberation.

• Research in Community and Public Health Nursing
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• v.19 no.3
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• pp.495-505
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• 2008

Purpose: This study was conducted to identify the relation between farmers' syndrome and the quality of life of residents in suburban areas. Methods: A total of 994 subjects were selected through simple random sampling. Data were collected from June 25 to August 31, 2007. Data analysis included frequency, $X^2$-test, Fisher's exact test, t-test, ANOVA, Duncan test, and Pearson's correlation coefficient using SPSS Win 12.0. Results: 1. Analysis of farmers' syndrome showed that there were statistically significant differences according to age, gender, education, living with, family conversation, health security, monthly income, occupation, general health status, systolic blood pressure, and sleeping time. 2. Analysis of the qualify of life showed that there were statistically significant differences according to age, education, religion, family conversation, health security, monthly income, occupation, and sleeping time. 3. Farmers' syndrome was in a significantly negative correlation with quality of life. Conclusions: Considering the results above, we need to develop nursing interventions for decreasing hypertension, high blood sugar, and farmers' syndrome of residents in suburban area.

• Research in Community and Public Health Nursing
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• v.22 no.2
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• pp.131-140
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• 2011

Purpose: This study was to identify the correlation between leisure activities and smoking/drinking of middle school students. Methods: Data were collected through a questionnaire survey of 298 middle school students from the $2^{nd}$ to $30^{th}$ of September, 2009. Collected data were analyzed statistically using frequency, $x^2$ test, t-test, ANOVA, Duncan test, Pearson's correlation coefficient, and hierarchical multiple regression analysis using the SPSS/WIN 17.0 program. The study used the Adolescent Leisure Time Activities Scale (ALTAS) developed by Yin et al. (1999) for types of leisure activities and the Leisure Satisfaction Scale (LSS) developed by Beard & Ragheb (1980). Results: First, smoking/drinking caused significant differences in 'Socialization with friends', and drinking also caused significant differences in 'Sport activities'. Second, leisure satisfaction was positively correlated with 'currently drinking' (r=.126, p<.05). Third, significant factors influencing leisure satisfaction were grades, school life satisfaction, subjective health status, average daily leisure time, participation in leisure health program, and current drinking. These variables explained 23.4% of leisure satisfaction. Conclusion: School nurses should develop and run programs, which promote healthy ways for middle school students with wrong ways such as drinking to get leisure satisfaction. Also family, school and community should be cooperatively connected with one another.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.7
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• pp.647-655
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• 2008

This paper presents real-time algorithm for an ultrasonic Local Positioning System(LPS). An ultrasonic LPS consists of 4 transmitters and n receivers. Each transmitter transmits an sequential ultrasonic signal to avoid interference of ultrasonic signal. This method is a noneffective application for a fast object. Because receiver detects four sequential transmissive ultrasonic signal and calculates a position. This paper proposes the method which 4 transmitters transmit simultaneous ultrasonic signal and each transmitter distinguished by frequencies and codes. And Auto-Correlation Function(ACF) method separates codes from an ultrasonic echo signal which is interference of each transmitter's code. If the receiver uses only ACF method, it is difficult to implement real time application for increased computation. This paper implements LPS using dual frequencies and ACF method. Using dual frequencies reduces codes length. The reduced codes length save computation in ACF. To prove this algorithm by experiment, high performance DSP(digital signal processor) used. The result shows the performance of the designed system is good enough positioning.

• Journal of information and communication convergence engineering
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• v.8 no.3
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• pp.289-294
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• 2010

In the vehicle communication system, transferred information is needed to be detected as possible as fast in order to inform car status located in front and rear side. Through the moving vehicle information, we can avoid the crash caused by sudden break of front one or acquire to real time traffic data to check the detour road. To be connecting the wireless communication between the vehicles, fast timing synchronization can be a key factor. Finding out the sync point fast is able to have more marginal time to compensate the distorted signals caused by channel variance. Thus, we introduce the combination method which helps find out the start of frame quickly. It is executed by auto-correlation and cross-correlation simultaneously using only short preambles. With taking the absolute value at the implemented synch block output, the proposed method shows much better system performance to us.

• Wind and Structures
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• v.16 no.5
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• pp.517-540
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• 2013

This paper presents applications of proper orthogonal decomposition in both the time and frequency domains based on both cross spectral matrix and covariance matrix branches to analyze multi-variate unsteady pressure fields on prisms and to study spanwise and chordwise pressure distribution. Furthermore, modification of proper orthogonal decomposition is applied to a rectangular spanwise coherence matrix in order to investigate the spanwise correlation and coherence of the unsteady pressure fields. The unsteady pressure fields have been directly measured in wind tunnel tests on some typical prisms with slenderness ratios B/D=1, B/D=1 with a splitter plate in the wake, and B/D=5. Significance and contribution of the first covariance mode associated with the first principal coordinates as well as those of the first spectral eigenvalue and associated spectral mode are clarified by synthesis of the unsteady pressure fields and identification of intrinsic events inside the unsteady pressure fields. Spanwise coherence of the unsteady pressure fields has been mapped the first time ever for better understanding of their intrinsic characteristics.

• Wind and Structures
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• v.33 no.6
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• pp.423-435
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• 2021

Although existing algorithms can predict wind speed using historical observation data, for engineering feasibility, most use moment methods and probability density functions to estimate fitted parameters. However, extreme wind speed prediction accuracy for long-term return periods is not always dependent on how the optimized frequency distribution curves are obtained; long-term return periods emphasize general distribution effects rather than marginal distributions, which are closely related to potential extreme values. Moreover, there are different wind speed parent sample types; how to theoretically select the proper extreme value distribution is uncertain. The influence of different sampling time intervals has not been evaluated in the fitting process. To overcome these shortcomings, updated steps are introduced, involving parameter sensitivity analysis for different sampling time intervals. The extreme value prediction accuracy of unknown parent samples is also discussed. Probability analysis of mean wind is combined with estimation of the probability plot correlation coefficient and the maximum likelihood method; an iterative estimation algorithm is proposed. With the updated steps and comparison using a Monte Carlo simulation, a fitting policy suitable for different parent distributions is proposed; its feasibility is demonstrated in extreme wind speed evaluations at Longhua and Chuansha meteorological stations in Shanghai, China.

• Journal of the Semiconductor & Display Technology
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• v.22 no.4
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• pp.13-18
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• 2023

A subway station is a prominent multi-purpose facility where the quantitative management of fine dust, generated by various factors, is conducted. Recently, eco-friendly air purification methods using air-purifying plants are being discussed, with the focus on biofiltration through vegetation. Previous research in this field has confirmed the reduction effects of transition metals such as Fe, which have been identified as harmful to human health. This study aimed to identify the sources of fine dust dispersion within subway stations and derive an efficient operational strategy for air-purifying plants that takes into account the behavior characteristics of fine dust within multi-purpose facilities. The experiment monitored regional fine dust levels through IAQ stations established based on prior research. Also, the data was analyzed through time-series and correlation analyses by linking it with passenger counts at subway stations and the frequency of train stops. Furthermore, to consider energy efficiency, we conducted component-specific power consumption monitoring. Through this study, we were able to derive the optimal operational strategy for air-purifying plants based on time-series comprehensive analysis data and confirm significant energy efficiency.

• Journal of the East Asian Society of Dietary Life
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• v.16 no.6
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• pp.772-776
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• 2006

The purpose of this study was to examine the differences in satisfaction of leisure life and quality of life using standardized evaluation tools developed by WHO. Resource availability when dining out was measured by objective index(time of dining out, dining out expense) and subjective index(perceived satisfaction with time of dining out and dining out expense). In this study, 500 questionnaires(male & female adults) located in Seoul and the metropolitan area were sampled by convenience sampling and gather in 433 sheets of questionnaire. Data was analyzed by frequency analysis, factor analysis, reliability analysis, correlation analysis and regression analysis using SPSS Win 12.0. As a result there was high positive correlation between time of dining out, dining out expense and perceived satisfaction with time of dining out and dining out expense. Moreover, dining out resources impact on leisure life satisfaction and quality of life. Leisure life satisfaction had fairly high effects on quality of life. Since there is an increase in leisure time the desire to improve quality of life while enjoying dining out as a part of leisure life is increasing and as various forms of consumption takes place, it suggests that segmentation of dining out market is necessary and marketing strategy should be established.